CN113043690A

CN113043690A - Metal-clad laminate and circuit board

Info

Publication number: CN113043690A
Application number: CN202011550852.XA
Authority: CN
Inventors: 铃木智之
Original assignee: Nippon Steel and Sumikin Chemical Co Ltd
Current assignee: Nippon Steel Chemical and Materials Co Ltd
Priority date: 2019-12-27
Filing date: 2020-12-24
Publication date: 2021-06-29
Anticipated expiration: 2040-12-24
Also published as: TWI865703B; KR20210084275A; JP2021106248A; CN113043690B; TW202126128A

Abstract

The invention provides a metal-clad laminate and a circuit board, which can reduce transmission loss even in high-frequency transmission and have excellent dimensional stability. The metal clad laminate comprises: the multilayer optical waveguide device includes a first metal layer, a first transmission loss suppression layer in contact with one side of the first metal layer, a second transmission loss suppression layer in contact with one side of the second metal layer, and a multilayer resin layer interposed between the first transmission loss suppression layer and the second transmission loss suppression layer. The resin laminate comprises a first transmission loss suppression layer, a second transmission loss suppression layer, at least two or more dimensional accuracy maintenance layers, and an intermediate transmission loss suppression layer laminated between the dimensional accuracy maintenance layers. In the metal-clad laminate, Df represents the dielectric loss tangent of the first transmission loss suppression layer and the second transmission loss suppression layer at 10GHz₁Df is the dielectric loss tangent of the dimensional accuracy maintaining layer₂Then, Df₁＜Df₂。

Description

Metal-clad laminate and circuit board

Technical Field

The present invention relates to a metal-clad laminate and a circuit board which are effectively used as electronic components.

Background

In recent years, with the progress of downsizing, weight saving, and space saving of electronic devices, there has been an increasing demand for a Flexible Printed circuit board (FPC) that is thin and lightweight, has flexibility, and has excellent durability even when repeatedly bent. Since FPCs can be mounted in a limited space in a three-dimensional and high-density manner, their applications are expanding in parts such as wiring, cables, and connectors of movable parts of electronic devices such as Hard Disk Drives (HDDs), Digital Video Disks (DVDs), and smartphones.

In addition to the above-described high density, the performance of the device is improved, and therefore, it is necessary to cope with the high frequency of the transmission signal. When a high-frequency signal is transmitted, if transmission loss in a transmission path is large, problems such as loss of an electric signal and a long delay time of the signal occur. Therefore, in FPC, reduction of transmission loss is also important in the future.

In order to improve high-frequency transmission characteristics, it has been proposed to use, as an insulating resin layer, a laminate in which films containing a fluororesin are laminated on both surfaces of a polyimide film (patent document 1). The insulating resin layer of patent document 1 is excellent in dielectric characteristics because it uses a fluorine-based resin, but has a problem in dimensional stability, and particularly when applied to an FPC, there is a concern that dimensional changes before and after circuit processing and dimensional changes before and after heat treatment due to etching become large.

In order to improve high-frequency transmission characteristics, it has been proposed to laminate two single-sided metal-clad laminates by introducing an adhesive layer having a specific diamine residue, and to control the thickness of the entire resin layer and the adhesive layer (patent document 2). However, in patent document 2, the distance between the adhesive layer having a low dielectric loss tangent and the metal layer (wiring) is long due to the insulating layer of the single-sided metal-clad laminate, and therefore the effect of reducing the transmission loss is still further improved.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open No. 2004-216830

[ patent document 2] Japanese patent laid-open No. 2018-170417

Disclosure of Invention

[ problems to be solved by the invention ]

The purpose of the present invention is to provide a metal-clad laminate and a circuit board that can reduce transmission loss even in high-frequency transmission and have excellent dimensional stability.

[ means for solving problems ]

The present inventors have made diligent studies and, as a result, have found that: by providing transmission loss suppression layers of low dielectric loss tangent in contact with the pair of metal layers (wiring lines), and providing a structure in which a plurality of dimensional accuracy maintenance layers are stacked with an intermediate transmission loss suppression layer between the transmission loss suppression layers, and setting the ratio of the total thickness of the dimensional accuracy maintenance layers to the thickness of the entire resin layer to be constant or more, even if the thickness of the entire resin layer is increased, the positional deviation of the wiring lines can be suppressed, and the reduction of the transmission loss and the maintenance of the dimensional accuracy can be achieved at the same time.

The metal-clad laminate of the present invention comprises: the multilayer optical waveguide device includes a first metal layer, a first transmission loss suppression layer provided in contact with one side of the first metal layer, a second transmission loss suppression layer provided in contact with one side of the second metal layer, and a multilayer resin layer interposed between the first transmission loss suppression layer and the second transmission loss suppression layer.

In the metal-clad laminate of the present invention, a resin laminate is formed of the first transmission loss suppression layer, the second transmission loss suppression layer, and the plurality of resin layers, and the resin laminate has at least two or more dimensional accuracy maintenance layers and an intermediate transmission loss suppression layer laminated between the dimensional accuracy maintenance layers.

The metal-clad laminate of the present invention satisfies the following conditions i and ii;

i) the dielectric loss tangent of the first transmission loss suppression layer and the second transmission loss suppression layer is Df₁And Df is the dielectric loss tangent of the dimensional accuracy maintaining layer₂At time, at Df₁＜Df₂A Dielectric loss tangent at 10GHz measured by separating a Dielectric Resonator (SPDR) after humidity conditioning for 24 hours under constant temperature and humidity conditions (normal state) at 23 ℃ and 50% RH;

ii) the total thickness of the dimensional accuracy-maintaining layers is in the range of 25% to 60% of the total thickness of the resin laminate.

The circuit board of the present invention includes: the multilayer wiring board includes a first wiring layer, a first transmission loss suppression layer provided in contact with one side of the first wiring layer, a second transmission loss suppression layer provided in contact with one side of the second wiring layer, and a multilayer resin layer interposed between the first transmission loss suppression layer and the second transmission loss suppression layer.

In the circuit board of the present invention, the first transmission loss suppressing layer, the second transmission loss suppressing layer, and the plurality of resin layers form a resin laminate, and the resin laminate has at least two or more dimensional accuracy maintaining layers and an intermediate transmission loss suppressing layer laminated between the dimensional accuracy maintaining layers.

The circuit board of the present invention satisfies the following conditions i and ii;

i) the dielectric loss tangent of the first transmission loss suppression layer and the second transmission loss suppression layer is Df₁And Df is the dielectric loss tangent of the dimensional accuracy maintaining layer₂At time, at Df₁＜Df₂The dielectric loss tangent is constant at 23 ℃ and 50% RHDielectric loss tangent at 10GHz measured by separating a dielectric resonator (SPDR) after humidity conditioning for 24 hours under temperature and humidity conditions (normal state);

In the metal-clad laminate or the circuit board of the present invention, the dimensional accuracy maintaining layer may be a low thermal expansion polyimide layer having a minimum value of a storage elastic coefficient in a temperature range of 100 ℃ to 250 ℃ in a range of 1.0GPa to 8.0GPa and a thermal expansion coefficient in a range of 15ppm/K to 25 ppm/K.

In the metal-clad laminate or the circuit board of the present invention, the resin constituting the first transmission loss suppression layer and the second transmission loss suppression layer may be a polyimide obtained by reacting an acid anhydride component with a diamine component, and the dimer diamine may contain at least 50 parts by mole of dimer acid in which both terminal carboxylic acid groups of the dimer acid are substituted with primary aminomethyl groups or amino groups, based on 100 parts by mole of the total amount of the diamine component.

[ Effect of the invention ]

Since the metal-clad laminate of the present invention is provided with the transmission loss suppressing layers having low dielectric loss tangents so as to be in contact with the pair of metal layers (wirings), the transmission loss in high-frequency signal transmission can be effectively suppressed. Further, since a structure in which a plurality of dimensional accuracy maintaining layers and intermediate transmission loss suppressing layers are stacked is provided between the transmission loss suppressing layers and the ratio of the total thickness of the dimensional accuracy maintaining layers to the thickness of the entire resin layer is set to be constant or more, it is possible to realize low dielectric constant while securing high dimensional stability. Therefore, when the metal-clad laminate of the present invention is applied to a circuit board or the like that transmits a high-frequency signal having a frequency of 10GHz or more, for example, the transmission loss can be effectively reduced.

Drawings

Fig. 1 is a schematic view showing the structure of a metal-clad laminate according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view showing the structure of a metal-clad laminate according to another embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view showing the structure of a metal-clad laminate according to still another embodiment of the present invention.

Fig. 4 is a schematic cross-sectional view showing a structural example of the dimensional accuracy maintaining layer.

Description of the symbols

10: metal-clad laminated board

20: resin laminate

M1: a first metal layer

M2: second metal layer

BS 1: first transmission loss suppressing layer

BS 2: second transmission loss suppressing layer

BS 3: intermediate transmission loss suppressing layer

PL: dimensional accuracy maintaining layer

31: non-thermoplastic polyimide layer

33: thermoplastic polyimide layer

Detailed Description

Embodiments of the present invention will be described with reference to the accompanying drawings.

[ Metal-clad laminate ]

Fig. 1 is a schematic view showing the structure of a metal-clad laminate according to an embodiment of the present invention. The metal-clad laminate 10 of the present embodiment includes:

a first metal layer M1,

A first transmission loss suppressing layer BS1 disposed in contact with one side of the first metal layer M1,

A second metal layer M2,

A second transmission loss suppression layer BS2 provided in contact with one side of the second metal layer M2, and

a plurality of resin layers are interposed between the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS 2.

Since the metal-clad laminate 10 is provided with the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2 having low dielectric loss tangents at the positions closest to the pair of metal layers (the first metal layer M1 and the second metal layer M2 to be wirings), respectively, the transmission loss during high-frequency signal transmission can be effectively suppressed.

Here, the resin laminate 20 is formed of the first transmission loss suppression layer BS1, the second transmission loss suppression layer BS2, and the plurality of resin layers. The resin laminate 20 includes at least two or more dimensional accuracy maintaining layers PL and an intermediate transmission loss suppressing layer BS3 laminated between the dimensional accuracy maintaining layers PL, in addition to the first transmission loss suppressing layer BS1 and the second transmission loss suppressing layer BS 2.

As described above, by providing the stacked structure of the dimensional accuracy maintaining layer PL and the intermediate transmission loss suppression layer BS3 between the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2, it is possible to realize low dielectric constant while securing high dimensional stability.

The resin laminate 20 may have any resin layer other than the above, but is preferably formed only of the resin layers having the above functions.

As shown in fig. 1, the first metal layer M1 and the second metal layer M2 are located at the outermost sides, and the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2 are arranged in contact with the inner sides thereof, and further, a plurality of resin layers including a plurality of dimensional accuracy maintenance layers PL and an intermediate transmission loss suppression layer BS3 are arranged between the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS 2. Here, the first transmission loss suppression layer BS1 is adjacent to one dimensional accuracy maintaining layer PL, and the second transmission loss suppression layer BS2 is in contact with the other dimensional accuracy maintaining layer PL.

The metal-clad laminate 10 shown in fig. 1 has two dimensional accuracy maintaining layers PL and one intermediate transmission loss suppressing layer BS3, but the dimensional accuracy maintaining layer PL may be two or more layers, and the number of layers of the intermediate transmission loss suppressing layer BS3 is not particularly limited. For example, as shown in fig. 2, the structure may be one having three dimensional accuracy maintaining layers PL and two intermediate transmission loss suppression layers BS3, or, as shown in fig. 3, the structure may be one having five dimensional accuracy maintaining layers PL and four intermediate transmission loss suppression layers BS 3.

In the metal-clad laminate 10, the first metal layer M1 and the second metal layer M2 may have the same or different structures, but are preferably made of the same material, have the same physical properties, and have the same thickness.

The first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2 may have the same or different structures, but are preferably made of the same material, have the same physical properties, and have the same thickness. For example, by making the dielectric loss tangent or the thickness of the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2 the same, the transmission loss reduction design in the case of manufacturing the circuit board for high-frequency transmission becomes easy.

Further, the first transmission loss suppression layer BS1, the second transmission loss suppression layer BS2, and the intermediate transmission loss suppression layer BS3 may have the same or different structures, but in order to improve the dielectric characteristics of the entire resin laminate 20 and effectively suppress the transmission loss of a high-frequency signal, the same material and the same physical properties are preferable.

The plurality of dimensional accuracy maintaining layers PL may have the same or different structures, but are preferably the same material, the same physical properties, the same thickness, and the same layer structure in terms of ease of designing mechanical strength and dimensional accuracy in manufacturing the circuit board.

The metal-clad laminate 10 satisfies the following conditions i and ii.

Condition i:

df represents the dielectric loss tangent of the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2₁Df is the dielectric loss tangent of the dimensional accuracy maintaining layer PL₂At time, at Df₁＜Df₂The relationship (2) of (c).

Dielectric loss tangent Df of the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2 which are respectively connected with the first metal layer M1 and the second metal layer M2 of the circuit wiring which is a transmission path of high-frequency signals₁Designed to be lower than the dielectric loss tangent Df of the dimensional accuracy maintaining layer PL₂The transmission loss of the high-frequency signal can be effectively suppressed. Further, even when the dielectric loss tangents of the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2 are different from each other, it is necessary to satisfy Df₁＜Df₂The relationship (2) of (c). In the present invention, the content of the compound is not particularly limitedThe dielectric constant and the dielectric loss tangent are dielectric constants and dielectric loss tangents at 10GHz measured by separating the dielectric resonator (SPDR) after humidity conditioning for 24 hours under constant temperature and humidity conditions (normal state) at 23 ℃ and 50% RH.

From the viewpoint of suppressing the transmission loss of a high-frequency signal, the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2 have dielectric loss tangents Df at 10GHz₁Preferably 0.005 or less, more preferably 0.003 or less.

From the viewpoint of suppressing the transmission loss of the high-frequency signal, the dielectric loss tangent Df of the intermediate transmission loss suppression layer BS3 at 10GHz measured in the same manner as in condition i₃Preferably 0.005 or less, more preferably 0.003 or less, and most preferably the dielectric loss tangent Df to the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2₁The same is true.

In addition, the dielectric loss tangent Df of the dimensional accuracy maintaining layer PL₂It is desirable to be as low as possible, but since the layer is a layer whose main purpose is to maintain dimensional accuracy and mechanical strength, it is preferably 0.012 or less, and more preferably 0.010 or less, on the premise that the condition i is satisfied. The reason is that: even if the dielectric loss tangent Df of the dimensional accuracy maintaining layer PL₂By stacking the first transmission loss suppression layer BS1, the second transmission loss suppression layer BS2, and the intermediate transmission loss suppression layer BS3, which have a lower dielectric loss tangent, slightly higher than the above, and taking into consideration the thickness ratio thereof, it is possible to ensure low dielectric constant of the entire resin laminate 20.

Condition ii:

total thickness T of dimensional accuracy maintaining layer PL_PLThe total thickness T of the resin laminate 20 (i.e., the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2, the one or more intermediate transmission loss suppression layers BS3, and the multiple dimensional accuracy maintenance layers PL) is in the range of 25% to 60%.

By maintaining the total thickness T of the layers PL with multiple dimensional accuracies_PLThe ratio of the total thickness T of the resin laminate 20 to the total thickness T of the resin laminate is within the above range, and the circuit processing of the metal-clad laminate 10 can be maintainedThe dimensional accuracy and mechanical strength in time, and the reduction of transmission loss of high-frequency signals can be realized. From the viewpoint, the thickness T_PLThe ratio to the total thickness T is preferably in the range of 25% to 50%.

Here, the thickness of each layer in the resin laminate 20 is not particularly limited since it can be appropriately set according to the purpose of use, but can be exemplified as described below.

The thickness of one of the first transmission loss suppression layer BS1 and the second transmission loss suppression layer BS2 is preferably in the range of 2 μm to 100 μm, and more preferably in the range of 5 μm to 75 μm.

The thickness of one layer of the dimensional accuracy maintaining layer PL is preferably within a range of 10 μm to 100 μm, and more preferably within a range of 12 μm to 50 μm.

The thickness of one layer of the intermediate transmission loss suppression layer BS3 is preferably in the range of 12 μm to 150 μm, and more preferably in the range of 25 μm to 100 μm.

The total thickness T of the resin laminate 20 is preferably in the range of 50 to 300 μm, and more preferably in the range of 75 to 200 μm.

In order to realize low dielectric characteristics of the entire resin laminate 20, the total thickness T of the first transmission loss suppression layer BS1, the second transmission loss suppression layer BS2, and the intermediate transmission loss suppression layer BS3 is set to be equal to_BThe content is preferably in the range of 40% to 75%, and more preferably in the range of 50% to 75% with respect to the total thickness T of the resin laminate 20.

The layers constituting the metal-clad laminate 10 will be described below.

[ Metal layer ]

The materials of the first metal layer M1 and the second metal layer M2 are not particularly limited, and examples thereof include: copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, alloys thereof, and the like. Among them, copper or a copper alloy is particularly preferable. The wiring layer in the circuit board of the present embodiment to be described later is made of the same material as the first metal layer M1 and the second metal layer M2.

The thicknesses of the first metal layer M1 and the second metal layer M2 are not particularly limited, and when a metal foil such as copper foil is used, for example, the thickness is preferably 35 μ M or less, and more preferably in the range of 5 μ M to 25 μ M. From the viewpoint of production stability and handling property, the lower limit of the thickness of the metal foil is preferably set to 5 μm. When a copper foil is used, the copper foil may be a rolled copper foil or an electrolytic copper foil. As the copper foil, a commercially available copper foil can be used.

For example, the metal foil may be subjected to surface treatment with a wallboard (fixing), an aluminum alcoholate, an aluminum chelate compound, a silane coupling agent, or the like for the purpose of, for example, rust prevention treatment or improvement of adhesion.

[ Transmission loss suppressing layer ]

The glass transition temperature (Tg) of the resin constituting the first transmission loss suppression layer BS1, the second transmission loss suppression layer BS2, and the intermediate transmission loss suppression layer BS3 (hereinafter, these may be collectively referred to as "transmission loss suppression layers BS1 to BS 3") is preferably 180 ℃ or lower, and more preferably 160 ℃ or lower. By setting the glass transition temperature of the transmission loss suppression layers BS1 to BS3 to 180 ℃ or lower, thermocompression bonding at a low temperature is possible, and therefore, internal stress generated at the time of lamination can be relaxed, and dimensional change after circuit processing can be suppressed. When Tg of the transmission loss suppression layers BS1 to BS3 exceeds 180 ℃, the temperature at the time of bonding between the dimensional accuracy maintaining layers PL becomes high, and dimensional stability after circuit processing may be impaired.

The maximum value of the storage elastic modulus in the temperature range of 100 ℃ to 250 ℃ is preferably 1.0GHz or less from the transmission loss suppression layer BS1 to the transmission loss suppression layer BS 3. Such a storage modulus of elasticity can relax the internal stress during thermocompression bonding and maintain the dimensional stability after circuit processing. Further, even after the reflow step after circuit processing, warpage is less likely to occur.

The resin constituting the first transmission loss suppression layer BS1, the second transmission loss suppression layer BS2, and the intermediate transmission loss suppression layer BS3 is preferably a polyimide, and more preferably a thermoplastic polyimide (hereinafter, sometimes referred to as "DDA-based polyimide") obtained by imidizing a polyamic acid which is a precursor obtained by reacting an acid anhydride component with a diamine component containing 50 parts by mole or more of a diamine dimer in which both terminal carboxylic acid groups of a dimer acid are substituted with a primary aminomethyl group or an amino group, or a crosslinked cured product thereof, with respect to 100 parts by mole of the total amount of the diamine component. In the present invention, the term "polyimide" refers to resins containing a polymer having an imide group in its molecular structure, such as polyamideimide, polyetherimide, polyesterimide, polysiloxane imide, and polybenzimidazole imide, in addition to polyimide.

< polyimide of DDA series >

DDA-based polyimides are aliphatic thermoplastic polyimides, have high flexibility, have sufficient toughness even when a large amount of a liquid crystalline polymer filler is added, and have high ability to retain their shape when formed into a resin film.

The DDA polyimide contains a tetracarboxylic acid residue derived from a tetracarboxylic acid anhydride as a raw material and a diamine residue derived from a diamine compound as a raw material. In the present invention, the tetracarboxylic acid residue represents a tetravalent group derived from a tetracarboxylic dianhydride, and the diamine residue represents a divalent group derived from a diamine compound. The tetracarboxylic acid residue and the diamine residue contained in the DDA polyimide can be substantially matched in type and amount to the starting material by reacting the tetracarboxylic acid anhydride and the diamine compound as the starting materials in substantially equimolar amounts.

(acid anhydride component)

The DDA polyimide may be produced using a tetracarboxylic anhydride generally used for thermoplastic polyimides without any particular limitation, but preferably contains a tetracarboxylic anhydride represented by the following general formula (1) and/or general formula (2) in a total amount of 90 mol% or more based on the total anhydride components. In other words, the DDA polyimide preferably contains 90 parts by mole or more of tetracarboxylic acid residues derived from tetracarboxylic acid anhydrides represented by the following general formula (1) and/or general formula (2) in total per 100 parts by mole of all tetracarboxylic acid residues. The use of 90 parts by mole or more of a tetracarboxylic acid residue derived from a tetracarboxylic acid anhydride represented by the following general formula (1) and/or general formula (2) in total per 100 parts by mole of the tetracarboxylic acid residue is preferable because flexibility and heat resistance of the DDA polyimide can be easily achieved. When the total amount of tetracarboxylic acid residues derived from the tetracarboxylic anhydride represented by the following general formula (1) and/or general formula (2) is less than 90 parts by mole, the solvent solubility of the DDA polyimide tends to decrease.

[ solution 1]

In the general formula (1), X represents a single bond or a divalent group selected from the group consisting of the following formulas, and in the general formula (2), the cyclic moiety represented by Y represents a cyclic saturated hydrocarbon group forming a ring selected from a 4-membered ring, a 5-membered ring, a 6-membered ring, a 7-membered ring, or an 8-membered ring.

[ solution 2]

In the formula, Z represents-C₆H₄-、-(CH₂) n-or-CH₂-CH(-O-C(＝O)-CH₃)-CH₂N represents an integer of 1 to 20.

Examples of the tetracarboxylic anhydride represented by the general formula (1) include: 3,3',4,4' -biphenyltetracarboxylic dianhydride (3,3',4,4' -biphenyltetracarboxylic dianhydride, BPDA), 3',4,4' -benzophenonetetracarboxylic dianhydride (3,3',4,4' -benzophenonetetracarboxylic dianhydride, BTDA), 3',4,4' -diphenylsulfonetetracarboxylic dianhydride (3,3',4,4' -diphenylsulfon tetracarboxylic dianhydride, DSDA), 4,4'-oxydiphthalic anhydride (4,4' -oxydiphthalic dianhydride, ODPA), 4,4'- (hexafluoroisopropylidene) diphthalic anhydride (4,4' - (hexafluoroisopropylidene) diphthalic anhydride, 6FDA), 2-bis [4- (3, 4-hydroxyphenoxy) phenyl ] propane dianhydride (2,2-bis [4- (3, 4-dicarboxyphenyl ] propane dianhydride, BPADA), p-phenylene bis (trimellitic acid monoester) anhydride (TAHQ), ethylene glycol bistrimellitic anhydride (TMEG), and the like. Among these, 3',4,4' -Benzophenone Tetracarboxylic Dianhydride (BTDA) is particularly preferable. In the case of using BTDA, the carbonyl group (ketone group) contributes to the adhesiveness, and thus the adhesiveness of DDA-based polyimide can be improved. BTDA is likely to exhibit an effect of improving heat resistance when a ketone group present in a molecular skeleton reacts with an amino group of an amino compound to be crosslinked as described below to form a C ═ N bond. From this viewpoint, the amount of the BTDA-derived tetracarboxylic acid residue is preferably 50 parts by mole or more, more preferably 60 parts by mole or more, per 100 parts by mole of the tetracarboxylic acid residue.

Examples of the tetracarboxylic anhydride represented by the general formula (2) include: 1,2,3, 4-cyclobutanetetracarboxylic dianhydride, 1,2,3, 4-cyclopentanetetracarboxylic dianhydride, 1,2,4, 5-cyclohexanetetracarboxylic dianhydride, 1,2,4, 5-cycloheptanetetracarboxylic dianhydride, 1,2,5, 6-cyclooctanetetracarboxylic dianhydride, etc.

The DDA polyimide may contain a tetracarboxylic acid residue derived from an acid anhydride other than the tetracarboxylic acid anhydrides represented by the general formulae (1) and (2) in a range not to impair the effects of the present invention. Examples of such tetracarboxylic acid residues include, but are not particularly limited to, pyromellitic dianhydride, 2,3',3,4' -biphenyltetracarboxylic acid dianhydride, 2',3,3' -benzophenonetetracarboxylic acid dianhydride or 2,3,3',4' -benzophenonetetracarboxylic acid dianhydride, 2,3',3,4' -diphenylethertetracarboxylic acid dianhydride, bis (2, 3-dicarboxyphenyl) ether dianhydride, 3,3',4,4' -p-terphenyltetracarboxylic acid dianhydride, 2,3,3',4' -p-terphenyltetracarboxylic acid dianhydride or 2,2',3,3' -p-terphenyltetracarboxylic acid dianhydride, 2-bis (2, 3-dicarboxyphenyl) -propane dianhydride or 2,2-bis (3, 4-dicarboxyphenyl) -propane dianhydride, Bis (2, 3-dicarboxyphenyl) methane dianhydride or bis (3, 4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) sulfone dianhydride or bis (3, 4-dicarboxyphenyl) sulfone dianhydride, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride or 1, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, 1,2,7, 8-phenanthrene-tetracarboxylic acid dianhydride, 1,2,6, 7-phenanthrene-tetracarboxylic acid dianhydride or 1,2,9, 10-phenanthrene-tetracarboxylic acid dianhydride, 2,3,6, 7-anthracenetetracarboxylic acid dianhydride, 2-bis (3, 4-dicarboxyphenyl) tetrafluoropropane dianhydride, 1,2,5, 6-naphthalenetetracarboxylic acid dianhydride, 1,4,5, 8-naphthalenetetracarboxylic acid dianhydride, 2,3,6, 7-naphthalenetetracarboxylic dianhydride, 4, 8-dimethyl-1, 2,3,5,6, 7-hexahydronaphthalene-1, 2,5, 6-tetracarboxylic dianhydride, 2, 6-dichloronaphthalene-1, 4,5, 8-tetracarboxylic dianhydride or 2, 7-dichloronaphthalene-1, 4,5, 8-tetracarboxylic dianhydride, 2,3,6,7- (or 1,4,5,8-) tetrachloronaphthalene-1, 4,5,8- (or 2,3,6,7-) tetracarboxylic dianhydride, 2,3,8, 9-perylene-tetracarboxylic dianhydride, 3,4,9, 10-perylene-tetracarboxylic dianhydride, 4,5,10, 11-perylene-tetracarboxylic dianhydride or 5,6,11, 12-perylene-tetracarboxylic dianhydride, Tetracarboxylic acid residues derived from aromatic tetracarboxylic acid dianhydrides such as pyrazine-2, 3,5, 6-tetracarboxylic acid dianhydride, pyrrolidine-2, 3,4, 5-tetracarboxylic acid dianhydride, thiophene-2, 3,4, 5-tetracarboxylic acid dianhydride, and 4,4' -bis (2, 3-dicarboxyphenoxy) diphenylmethane dianhydride.

(diamine component)

The DDA polyimide uses, as a raw material, a diamine component containing 50 parts by mole or more, and more preferably 70 parts by mole or more of dimer diamine in which both terminal carboxylic acid groups of dimer acid are substituted with primary aminomethyl groups or amino groups, based on 100 parts by mole of the total amount of the diamine component. By containing the dimer diamine in such an amount, the dielectric characteristics of the polyimide can be improved, and the thermal compression bonding characteristics can be improved by lowering the glass transition temperature (lowering Tg) of the polyimide and the internal stress can be relaxed by lowering the elastic modulus.

Dimer diamine refers to dimer acid having primary aminomethyl (-CH) groups bonded to the two terminal carboxylic acid groups (-COOH)₂-NH₂) Or amino (-NH)₂) Substituted diamines. Dimer acid is a known dibasic acid obtained by intermolecular polymerization of unsaturated fatty acids, and its industrial production process is generally standardized in the industry, and is obtained by dimerizing an unsaturated fatty acid having 11 to 22 carbon atoms using a clay catalyst or the like. The commercially available dimer acid contains a dibasic acid having 36 carbon atoms obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms such as oleic acid, linoleic acid, linolenic acid, etc., as a main component, and contains a monomer acid (having 18 carbon atoms), a trimer acid (having 54 carbon atoms), and other polymerized fatty acids having 20 to 54 carbon atoms in an arbitrary amount depending on the degree of purification. In addition, although a double bond remains after dimerization reaction, in the present invention, a dimer acid may further contain a double bond which is hydrogenated to lower the degree of unsaturationA compound (I) is provided. The dimer diamine is defined as a diamine compound obtained by substituting a terminal carboxylic acid group of a diacid compound having 18 to 54 carbon atoms, preferably 22 to 44 carbon atoms, with a primary aminomethyl group or an amino group.

As a feature of dimer diamine, a property derived from the skeleton of dimer acid can be imparted. That is, the dimer diamine is an aliphatic group of a macromolecule having a molecular weight of about 560 to 620, and thus the molar volume of the macromolecule can be increased and the polar group of the DDA polyimide can be relatively decreased. It is considered that such dimer acid-based diamine is characterized by contributing to the improvement of dielectric characteristics by reducing the dielectric constant and dielectric loss tangent while suppressing the decrease in heat resistance of the DDA-based polyimide. Further, since the DDA polyimide contains two freely movable hydrophobic chains having 7 to 9 carbon atoms and two chain aliphatic amino groups having a length close to 18 carbon atoms, flexibility can be imparted to the DDA polyimide, and the DDA polyimide can be formed to have an asymmetric chemical structure or a non-planar chemical structure, and thus it is considered that a low dielectric constant can be achieved.

The dimer diamine used in the present invention is preferably purified for the purpose of reducing components other than the dimer diamine. The purification method is not particularly limited, but a known method such as distillation or precipitation purification is suitable. The dimer diamine before purification can be obtained as a commercially available product, and examples thereof include: priiramine (praiamine) 1073 (trade name) manufactured by Croda japonica (Croda Japan), priiramine (praiamine) 1074 (trade name) manufactured by Croda japonica (Croda Japan), priiramine (praiamine) 1075 (trade name) manufactured by Croda japonica (Croda Japan), and the like.

Examples of the diamine compound other than dimer diamine used in DDA polyimide include aromatic diamine compounds and aliphatic diamine compounds. Specific examples thereof include: 1, 4-diaminobenzene (p-PDA (p-phenylenediamine)), 2' -dimethyl-4,4' -diaminobiphenyl (2,2' -dimethyl-4,4' -diamino-biphenyl, m-TB), 2' -n-propyl-4,4' -diaminobiphenyl (2,2' -n-propyl-4,4' -diamino-biphenyl, m-NPB), 4-aminophenyl-4 ' -aminobenzoate (4-amino-phenyl-4 ' -amino-benzoate, APAB), 2-bis- [4- (3-aminophenoxy) phenyl ] propane, bis [4- (3-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) ] biphenyl, N-methyl-4 ' -aminobenzoate, Bis [1- (3-aminophenoxy) ] biphenyl, bis [4- (3-aminophenoxy) phenyl ] methane, bis [4- (3-aminophenoxy) phenyl ] ether, bis [4- (3-aminophenoxy) ] benzophenone, 9-bis [4- (3-aminophenoxy) phenyl ] fluorene, 2-bis- [4- (4-aminophenoxy) phenyl ] hexafluoropropane, 2-bis- [4- (3-aminophenoxy) phenyl ] hexafluoropropane, 3 '-dimethyl-4,4' -diaminobiphenyl, 4 '-methylenebis-o-toluidine, 4' -methylenebis-2, 6-xylidine, 4,4 '-methylene-2, 6-diethylaniline, 3' -diaminodiphenylethane, 3 '-diaminobiphenyl, 3' -dimethoxybenzidine, 3 "-diamino-p-terphenyl, 4'- [1, 4-phenylenebis (1-methylethylidene) ] dianiline, 4' - [1, 3-phenylenebis (1-methylethylidene) ] dianiline, bis (p-aminocyclohexyl) methane, bis (p-beta-amino-tert-butylphenyl) ether, bis (p-beta-methyl-delta-aminopentyl) benzene, p-bis (2-methyl-4-aminopentyl) benzene, p-bis (1, 1-dimethyl-5-aminopentyl) benzene, p-bis (1-methyl-4-aminopentyl) benzene, p-bis (p-beta-, 1, 5-diaminonaphthalene, 2, 6-diaminonaphthalene, 2, 4-bis (. beta. -amino-tert-butyl) toluene, 2, 4-diaminotoluene, m-xylene-2, 5-diamine, p-xylene-2, 5-diamine, m-xylylenediamine, p-xylylenediamine, 2, 6-diaminopyridine, 2, 5-diamino-1, 3, 4-oxadiazole, piperazine, 2' -methoxy-4, 4' -diaminobenzanilide, 1,3-bis [2- (4-aminophenyl) -2-propyl ] benzene, 6-amino-2- (4-aminophenoxy) benzoxazole, 2, 4-bis (beta-amino-tert-butyl) toluene, 2, 4-diaminotoluene, 2, 5-diamine, 2, 4-diaminoxylene, 2' -diaminoxylene, Diamine compounds such as 1,3-bis (3-aminophenoxy) benzene.

The DDA polyimide can be produced as follows: the acid anhydride component and the diamine component are reacted in a solvent to produce a polyamic acid, and then the polyamic acid is heated to be closed. For example, a polyamic acid as a precursor of a polyimide can be obtained by dissolving an acid anhydride component and a diamine component in an organic solvent in approximately equimolar amounts, and stirring the solution at a temperature in the range of 0 to 100 ℃ for 30 minutes to 24 hours to perform a polymerization reaction. During the reaction, the reaction components are dissolved in the organic solvent so that the produced precursor is in the range of 5 to 50 wt%, preferably 10 to 40 wt%. Examples of the organic solvent used in the polymerization reaction include: n, N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, Dimethylsulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, methylcyclohexane, dioxane, tetrahydrofuran, diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), methanol, ethanol, benzyl alcohol, cresol, and the like. Two or more of these solvents may be used in combination, and an aromatic hydrocarbon such as xylene or toluene may be used in combination. The amount of the organic solvent used is not particularly limited, but is preferably adjusted so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 50 wt%.

The polyamic acid synthesized is advantageously used as a reaction solvent solution, and may be concentrated, diluted or replaced with another organic solvent as necessary. In addition, polyamic acid is generally excellent in solvent solubility and is therefore advantageously used. The viscosity of the solution of the polyamic acid is preferably in the range of 500 mPas to 100000 mPas. If the amount is outside the above range, defects such as uneven thickness and streaks are likely to occur in the film during coating work using a coater or the like.

The method for imidizing the polyamic acid to form the polyimide is not particularly limited, and for example, heat treatment such as heating at a temperature in the range of 80 to 400 ℃ for 1 to 24 hours in the solvent can be suitably employed. The temperature may be changed at a fixed temperature or during the process.

The dielectric characteristics, thermal expansion coefficient, tensile elastic coefficient, glass transition temperature, and the like can be controlled by selecting the types of the acid anhydride component and the diamine component in the DDA polyimide, or by selecting the molar ratio of each of two or more types of the acid anhydride component and the diamine component. In addition, when the DDA polyimide has a plurality of polyimide structural units, the blocks may be present or may be present randomly, but the random presence is preferable.

The weight average molecular weight of the DDA polyimide is preferably in the range of, for example, 10,000 to 200,000, and in such a range, the weight average molecular weight of the polyimide can be easily controlled. For example, when the DDA polyimide is used as an adhesive for FPC, the weight average molecular weight of the DDA polyimide is more preferably in the range of 20,000 to 150,000, and still more preferably in the range of 40,000 to 150,000. When the DDA polyimide is used as an adhesive for FPC, if the weight average molecular weight of the DDA polyimide is less than 20,000, the flow resistance tends to be deteriorated. On the other hand, when the weight average molecular weight of the DDA polyimide exceeds 150,000, the viscosity increases excessively and the DDA polyimide does not dissolve in a solvent, and thus defects such as uneven thickness and streaks of an adhesive layer tend to occur during coating operation.

The imide group concentration of the DDA polyimide is preferably 22 wt% or less, and more preferably 20 wt% or less. Here, the "imide group concentration" refers to the imide group (- (CO) in the polyimide₂A value obtained by dividing the molecular weight of-N-) by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 22% by weight, the molecular weight of the resin itself becomes small, and low hygroscopicity is also deteriorated due to an increase in polar groups, and Tg and the elastic modulus are increased.

The DDA polyimide is most preferably a completely imidized structure. However, a part of the polyimide may be amic acid. The imidization ratio can be measured by measuring the infrared absorption spectrum of the polyimide film by using a Fourier transform infrared spectrophotometer (commercially available product: FT/IR620 manufactured by Japanese Spectroscopy) and by the Attenuated Total Reflection (ATR) method at 1015cm^-1Based on the near benzene ring absorber, according to 1780cm^-1The absorbance of C ═ O stretching derived from the imide group (b) was calculated.

The DDA polyimide may be optionally blended with other hardening resin components such as plasticizers and epoxy resins, a hardening agent, a hardening accelerator, an inorganic filler, a coupling agent, a filler, a solvent, and a flame retardant.

[ Cross-linking formation of DDA polyimide ]

When the DDA polyimide has a ketone group, a crosslinked structure can be formed by reacting the ketone group with an amino group of an amino compound having at least two primary amino groups as functional groups (hereinafter, may be referred to as "crosslinking-forming amino compound") to form a C ═ N bond. The heat resistance of the DDA polyimide can be improved by forming a crosslinked structure. Examples of the tetracarboxylic anhydride preferable for forming the DDA polyimide having a ketone group include 3,3',4,4' -benzophenonetetracarboxylic dianhydride (BTDA), and examples of the diamine compound include aromatic diamines such as 4,4'-bis (3-aminophenoxy) benzophenone (4,4' -bis (3-aminophenoxy) benzophenone, BABP), and 1,3-bis [4- (3-aminophenoxy) benzoyl ] benzene (1,3-bis [4- (3-aminophenoxy) benzoyl ] benzene, BABB).

Particularly preferably, the crosslinked structure is formed from the DDA polyimide containing, based on the total tetracarboxylic acid residues, preferably 50 mol% or more, more preferably 60 mol% or more of BTDA derived BTDA residues and a crosslinking amino compound. In the present invention, the term "BTDA residue" refers to a tetravalent group derived from BTDA.

Examples of the amino compound for forming a crosslink include: (I) dihydrazide compounds, (II) aromatic diamines, (III) aliphatic amines, and the like. Among these, dihydrazide compounds are preferred. Aliphatic amines other than dihydrazide compounds tend to form a crosslinked structure even at room temperature, and thus the storage stability of varnish may be concerned. As described above, when the dihydrazide compound is used, both the storage stability of the varnish and the curing time can be reduced. The dihydrazide compounds include, for example, dihydrazide compounds such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecane acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, diethylene glycol dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2, 6-naphthalene carboxylic acid dihydrazide, 4-bis-benzene dihydrazide, 1, 4-naphthalene carboxylic acid dihydrazide, 2, 6-pyridine dicarboxylic acid dihydrazide, and itaconic acid dihydrazide. The dihydrazide compounds may be used alone or in combination of two or more.

The amino compound such as the dihydrazide compound (I), the aromatic diamine (II), and the aliphatic amine (III) may be used in combination of two or more kinds, for example, in a super-range of combinations such as a combination of (I) and (II), a combination of (I) and (III), and a combination of (I) and (II) and (III).

In addition, from the viewpoint of making the network structure formed by crosslinking with the crosslinking-forming amino compound denser, the molecular weight (weight average molecular weight in the case where the crosslinking-forming amino compound is an oligomer) of the crosslinking-forming amino compound used in the present invention is preferably 5,000 or less, more preferably 90 to 2,000, and even more preferably 100 to 1,500. Among them, particularly preferred is an amino compound for forming a crosslink, which has a molecular weight of 100 to 1,000. When the molecular weight of the amino compound for forming crosslinks is less than 90, one amino group of the amino compound for forming crosslinks forms a C ═ N bond with the ketone group of the DDA-based polyimide, and the volume around the remaining amino group increases sterically, so that the remaining amino group tends to be less likely to form a C ═ N bond.

In the case of crosslinking a ketone group in a DDA polyimide with a crosslinking amino compound, the crosslinking amino compound is added to a resin solution containing the DDA polyimide, and the ketone group in the DDA polyimide and a primary amino group of the crosslinking amino compound are subjected to a condensation reaction. The condensation reaction hardens the resin solution to form a hardened material. In this case, the amount of the amino compound for forming crosslinks added may be 0.004 to 1.5 moles, preferably 0.005 to 1.2 moles, more preferably 0.03 to 0.9 moles, and most preferably 0.04 to 0.6 moles, in total, of the primary amino groups with respect to 1 mole of the ketone groups. When the amount of the amino compound for forming a crosslink, which is less than 0.004 mol in total based on 1 mol of the ketone group, is more than 1.5 mol, the unreacted amino compound for forming a crosslink acts as a thermoplastic agent, and the heat resistance as an adhesive layer tends to be lowered.

The conditions for the condensation reaction for crosslinking formation are not particularly limited as long as the ketone group in the DDA polyimide reacts with the primary amino group of the amino compound for crosslinking formation to form an imine bond (C ═ N bond). The temperature of the heat condensation is preferably in the range of 120 to 220 ℃, and more preferably in the range of 140 to 200 ℃ for the reason of, for example, discharging water produced by condensation out of the system or simplifying the condensation step when the heat condensation reaction is performed after the synthesis of DDA polyimide. The reaction time is preferably about 30 minutes to 24 hours. The end point of the reaction can be determined by measuring the infrared absorption spectrum using, for example, a Fourier transform infrared spectrophotometer (commercially available product: FT/IR620 manufactured by Nippon spectral Co., Ltd.), and using 1670cm^-1The absorption peak derived from the ketone group in the polyimide resin in the vicinity was reduced or disappeared, and 1635cm^-1And the occurrence of an absorption peak derived from an imino group in the vicinity.

The thermal condensation of the ketone group of the DDA polyimide and the primary amino group of the amino compound for crosslinking can be carried out, for example, by the following method:

(1) a method in which an amino compound for crosslinking formation is added immediately after the synthesis (imidization) of a DDA polyimide and the mixture is heated;

(2) a method in which an excess amount of an amino compound is previously charged as a diamine component, and the remaining amino compound not involved in imidization or amidation is used as an amino compound for crosslinking formation and heated together with a DDA-based polyimide immediately after the synthesis (imidization) of the DDA-based polyimide;

or

(3) A method in which a DDA polyimide composition to which the amino compound for crosslinking formation is added is processed into a predetermined shape (for example, after being coated on an arbitrary substrate or formed into a film shape), and then heated.

In order to impart heat resistance to DDA-based polyimides, the formation of imine bonds has been described in the formation of a crosslinked structure, but the present invention is not limited thereto, and curing methods of polyimides may be, for example, those in which compounds having unsaturated bonds such as epoxy resins, epoxy resin curing agents, maleimide, activated ester resins, and resins having a styrene skeleton are blended and cured.

[ maintenance layer of dimensional accuracy ]

In order to maintain the mechanical strength of the metal clad laminate 10, the minimum value of the storage elastic coefficient in the temperature range of 100 ℃ to 250 ℃ is preferably in the range of 1.0GPa to 8.0GPa, and more preferably in the range of 2.0GPa to 6.0 GPa. If the minimum value of the storage elastic coefficient of the dimensional accuracy maintaining layer PL is less than 1.0GPa, sufficient mechanical strength and dimensional accuracy after circuit processing cannot be obtained. When the minimum value of the storage elastic modulus exceeds 8.0GPa, warpage is likely to occur during lamination pressing.

In addition, the dimensional accuracy maintaining layer PL has a Coefficient Of Thermal Expansion (CTE) in a range Of preferably 15 to 25ppm/K, and more preferably 16 to 23ppm/K, in order to maintain dimensional accuracy in circuit processing Of the metal clad laminate 10. If the CTE of the dimensional accuracy maintaining layer PL is less than 15ppm/K, the metal-clad laminate 10 is likely to warp, and if it exceeds 25ppm/K, the dimensional accuracy after circuit processing cannot be obtained.

The dimensional accuracy maintaining layer PL is not particularly limited as long as it contains a resin having electrical insulation properties, and examples thereof include polyimide, epoxy resin, phenol resin, polyethylene, polypropylene, polytetrafluoroethylene, silicone, Ethylene Tetrafluoroethylene (ETFE), and the like, and preferably contains polyimide. That is, the dimensional accuracy maintaining layer PL is preferably a single layer or a low thermal expansion polyimide layer including a plurality of layers.

When the dimensional accuracy maintaining layer PL is a single polyimide layer, the structure can be the same as that of the non-thermoplastic polyimide layer 31 described later. As the single-layer polyimide layer, commercially available products such as Kapton (Kapton) EN (trade name; manufactured by Toray dupont) and apikaru (apicaud) NPI (trade name; manufactured by KANEKA) can be used.

In the case where the dimensional accuracy maintaining layer PL includes a plurality of polyimide layers, as shown in fig. 4, the dimensional accuracy maintaining layer PL may be configured by, for example, laminating thermoplastic polyimide layers 33 including thermoplastic polyimide as a resin component on both sides of a non-thermoplastic polyimide layer 31 including non-thermoplastic polyimide as a resin component. The "non-thermoplastic polyimide" is usually a polyimide which does not soften or adhere even when heated, but in the present invention means that the storage elastic modulus at 30 ℃ measured with a Dynamic viscoelasticity measuring apparatus (Dynamic thermomechanical analyzer, DMA)) is 1.0 × 10⁹Pa or more and a storage modulus of elasticity at 350 ℃ of 1.0X 10⁸Polyimide having Pa or more. The "thermoplastic polyimide" is usually a polyimide whose glass transition temperature (Tg) is clearly observed, but in the present invention, it means that the storage elastic modulus at 30 ℃ measured by using DMA is 1.0X 10⁹Pa or more and a storage modulus of elasticity at 350 ℃ of less than 1.0X 10⁸Pa of a polyimide.

Next, a preferred configuration example of the non-thermoplastic polyimide layer 31 and the thermoplastic polyimide layer 33 constituting the dimensional accuracy maintaining layer PL will be described.

Non-thermoplastic polyimide layer:

the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 31 includes a tetracarboxylic acid residue and a diamine residue. The polyimide preferably contains an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic dianhydride and an aromatic diamine residue derived from an aromatic diamine.

(tetracarboxylic acid residue)

The non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 31 preferably contains, as tetracarboxylic acid residues, tetracarboxylic acid residues derived from at least one of 3,3',4,4' -biphenyltetracarboxylic dianhydride (BPDA) and 1, 4-phenylenebis (trimellitic acid monoester) dianhydride (TAHQ) and tetracarboxylic acid residues derived from at least one of Pyromellitic dianhydride (PMDA) and 2,3,6, 7-naphthalenetetracarboxylic dianhydride (NTCDA).

Tetracarboxylic acid residues derived from BPDA (hereinafter, also referred to as "BPDA residues") and TAHQ (hereinafter, also referred to as "TAHQ residues") readily form the ordered structure of the polymer, and the dielectric loss tangent or the moisture absorption can be reduced by suppressing the movement of the molecule. The BPDA residue can provide self-supporting properties to a gel film of a polyamic acid as a polyimide precursor, while increasing CTE after imidization and lowering glass transition temperature and heat resistance tend to be low.

From such a viewpoint, the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 31 is controlled to contain BPDA residues and TAHQ residues in a total amount of preferably 30 parts by mole or more and 60 parts by mole or less, more preferably 40 parts by mole or more and 50 parts by mole or less, with respect to 100 parts by mole of all tetracarboxylic acid residues. If the total amount of the BPDA residue and the TAHQ residue is less than 30 parts by mole, the formation of an ordered structure of the polymer becomes insufficient, the moisture absorption resistance decreases, or the dielectric loss tangent decreases insufficiently, and if it exceeds 60 parts by mole, there is a concern that the CTE increases, the amount of change in-plane Retardation (RO) increases, and the heat resistance decreases.

Further, a tetracarboxylic acid residue derived from pyromellitic dianhydride (hereinafter, also referred to as "PMDA residue") and a tetracarboxylic acid residue derived from 2,3,6, 7-naphthalenetetracarboxylic dianhydride (hereinafter, also referred to as "NTCDA residue") are residues that have rigidity, and therefore, improve in-plane orientation, suppress CTE to be low, and play a role in controlling in-plane Retardation (RO) or controlling glass transition temperature. On the other hand, since the molecular weight of the PMDA residue is small, if the amount thereof becomes too large, the imide group concentration of the polymer becomes high, the polar group increases, the hygroscopicity becomes large, and the dielectric loss tangent increases due to the influence of moisture in the molecular chain. Further, the NTCDA residue tends to increase the elastic coefficient and the film tends to be brittle due to the naphthalene skeleton having high rigidity.

Therefore, the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer contains PMDA residues and NTCDA residues in a total amount of preferably 40 parts by mole or more and 70 parts by mole or less, more preferably 50 parts by mole or more and 60 parts by mole or less, and still more preferably 50 parts by mole to 55 parts by mole with respect to 100 parts by mole of all tetracarboxylic acid residues. If the total amount of PMDA residues and NTCDA residues is less than 40 parts by mole, the CTE may increase or the heat resistance may decrease, and if it exceeds 70 parts by mole, the imide group concentration of the polymer may increase, the polar groups may increase, the hygroscopicity may decrease, and the dielectric loss tangent may increase; or the film may become brittle and the self-supporting properties of the film may decrease.

The total amount of at least one of BPDA residues and TAHQ residues and at least one of PMDA residues and NTCDA residues is preferably 80 parts by mole or more, more preferably 90 parts by mole or more, based on 100 parts by mole of all tetracarboxylic acid residues.

The formation of the ordered structure of CTE and polymer is preferably controlled so that the molar ratio of at least one of BPDA residue and TAHQ residue to at least one of PMDA residue and NTCDA residue { (BPDA residue + TAHQ residue)/(PMDA residue + NTCDA residue) } is in the range of 0.4 to 1.5, preferably in the range of 0.6 to 1.3, more preferably in the range of 0.8 to 1.2.

PMDA and NTCDA have a rigid skeleton, and therefore can control the in-plane orientation of molecules in polyimide as compared with other ordinary acid anhydride components, and have the effects of suppressing the Coefficient of Thermal Expansion (CTE) and increasing the glass transition temperature (Tg). In addition, BPDA and TAHQ have a higher molecular weight than PMDA, and therefore, the imide group concentration decreases with an increase in the input ratio, which has an effect on a decrease in the dielectric loss tangent and a decrease in the moisture absorption rate. On the other hand, if the input ratios of BPDA and TAHQ are increased, the in-plane orientation of molecules in polyimide decreases, and the CTE increases. Further, the formation of an ordered structure in the molecule is promoted, and the haze value is increased. From this viewpoint, the total amount of PMDA and NTCDA to be charged may be in the range of 40 to 70 mol parts, preferably in the range of 50 to 60 mol parts, and more preferably in the range of 50 to 55 mol parts, based on 100 mol parts of all the acid anhydride components in the raw materials. If the total amount of PMDA and NTCDA charged is less than 40 parts by mole based on 100 parts by mole of the total anhydride components of the raw materials, the in-plane orientation of the molecules is lowered, it is difficult to lower the CTE, and the heat resistance and dimensional stability of the film during heating are lowered due to the lowering of Tg. On the other hand, when the total amount of PMDA and NTCDA added exceeds 70 parts by mole, the moisture absorption rate tends to deteriorate or the elastic modulus tends to increase due to an increase in the imide group concentration.

BPDA and TAHQ have an effect on lowering the dielectric loss tangent and lowering the moisture absorption rate due to the suppression of molecular motion and the reduction in the imide group concentration, but increase the CTE of the polyimide film after imidization. From this viewpoint, the total amount of the BPDA and TAHQ to be charged may be in the range of 30 to 60 mol parts, preferably 40 to 50 mol parts, based on 100 mol parts of all the acid anhydride components in the raw materials.

Examples of the tetracarboxylic acid residue other than the BPDA residue, TAHQ residue, PMDA residue, and NTCDA residue contained in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 31 include tetracarboxylic acid residues other than the BPDA residue, TAHQ residue, and PMDA residue, and NTCDA residue, such as 3,3',4,4' -diphenylsulfone tetracarboxylic acid dianhydride, 4,4'-oxydiphthalic anhydride, 2,3',3,4 '-biphenyltetracarboxylic acid dianhydride, 2',3,3 '-benzophenonetetracarboxylic acid dianhydride, 2,3,3',4 '-benzophenonetetracarboxylic acid dianhydride, 2,3',3,4 '-diphenylether tetracarboxylic acid dianhydride, bis (2, 3-dicarboxyphenyl) ether dianhydride, 3,3',4,4 ″ -p-terphenyl tetracarboxylic acid dianhydride, 2,3,3 ″ -p-terphenyl tetracarboxylic acid dianhydride, or 2,2',3,3' -p-terphenyltetracarboxylic dianhydride, 2-bis (2, 3-dicarboxyphenyl) -propane dianhydride or 2,2-bis (3, 4-dicarboxyphenyl) -propane dianhydride, bis (2, 3-dicarboxyphenyl) methane dianhydride or bis (3, 4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) sulfone dianhydride or bis (3, 4-dicarboxyphenyl) sulfone dianhydride, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride or 1, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, 1,2,7, 8-phenanthrene-tetracarboxylic dianhydride, 1,2,6, 7-phenanthrene-tetracarboxylic dianhydride or 1,2,9, 10-phenanthrene-tetracarboxylic dianhydride, 2,3,6, 7-anthracenetetracarboxylic dianhydride, 2-bis (3, 4-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5, 6-cyclohexane dianhydride, 1,2,5, 6-naphthalenetetracarboxylic dianhydride, 1,4,5, 8-naphthalenetetracarboxylic dianhydride, 4, 8-dimethyl-1, 2,3,5,6, 7-hexahydronaphthalene-1, 2,5, 6-tetracarboxylic dianhydride, 2, 6-dichloronaphthalene-1, 4,5, 8-tetracarboxylic dianhydride or 2, 7-dichloronaphthalene-1, 4,5, 8-tetracarboxylic dianhydride, 2,3,6,7- (or 1,4,5,8-) tetrachloronaphthalene-1, 4,5,8- (or 2,3,6,7-) tetracarboxylic dianhydride, 2, tetracarboxylic acid residues derived from aromatic tetracarboxylic acid dianhydrides such as 3,8, 9-perylene-tetracarboxylic acid dianhydride, 3,4,9, 10-perylene-tetracarboxylic acid dianhydride, 4,5,10, 11-perylene-tetracarboxylic acid dianhydride or 5,6,11, 12-perylene-tetracarboxylic acid dianhydride, cyclopentane-1, 2,3, 4-tetracarboxylic acid dianhydride, pyrazine-2, 3,5, 6-tetracarboxylic acid dianhydride, pyrrolidine-2, 3,4, 5-tetracarboxylic acid dianhydride, thiophene-2, 3,4, 5-tetracarboxylic acid dianhydride, 4' -bis (2, 3-dicarboxyphenoxy) diphenylmethane dianhydride, ethylene glycol bistrimellitic anhydride and the like.

(diamine residue)

The diamine residue contained in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 31 is preferably a diamine residue derived from a diamine compound represented by the general formula (a 1).

[ solution 3]

In the formula (A1), the linking group Z represents a single bond or-COO-, Y independently represents a C1-3 monovalent hydrocarbon group which may be substituted with a halogen atom or a phenyl group, or a C1-3 alkoxy group or a C1-3 perfluoroalkyl group or alkenyl group, n represents an integer of 0-2, and p and q independently represent an integer of 0-4. Here, "independently" means that a plurality of substituents Y, the integer p, and the integer q may be the same or different in the formula (a 1). Further, in the formula (A1), the terminalThe hydrogen atoms in the two amino groups may be substituted, and may, for example, also be-NR₂R₃(Here, R is₂、R₃Independently, an optional substituent such as an alkyl group).

The diamine compound represented by the general formula (a1) (hereinafter, sometimes referred to as "diamine (a 1)") is an aromatic diamine having one to three benzene rings. The diamine (a1) has a rigid structure, and therefore has the effect of imparting an ordered structure to the entire polymer. Therefore, polyimide having low air permeability and low hygroscopicity can be obtained, and the dielectric loss tangent can be reduced by reducing the moisture in the molecular chain. Here, the linking group Z is preferably a single bond.

Examples of the diamine (a1) include: 1, 4-diaminobenzene (p-PDA; p-phenylenediamine), 2' -dimethyl-4,4' -diaminobiphenyl (m-TB), 2' -n-propyl-4,4' -diaminobiphenyl (m-NPB), 4-aminophenyl-4 ' -aminobenzoate (APAB), and the like.

The non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 31 preferably contains not less than 80 parts by mole, more preferably not less than 85 parts by mole of diamine residues derived from the diamine (a1) with respect to 100 parts by mole of the total diamine residues. By using the diamine (a1) in an amount within the above range and utilizing a rigid structure derived from a monomer, an ordered structure is easily formed in the entire polymer, and a non-thermoplastic polyimide having low gas permeability, low hygroscopicity, and a low dielectric loss tangent is easily obtained.

In addition, when the diamine residue derived from the diamine (a1) is in the range of 80 parts by mole or more and 85 parts by mole or less with respect to 100 parts by mole of the total diamine residues in the non-thermoplastic polyimide, 1, 4-diaminobenzene is preferably used as the diamine (a1) from the viewpoint of a more rigid structure having excellent in-plane orientation.

Examples of the other diamine residue contained in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 31 include those composed of 2, 2-bis- [4- (3-aminophenoxy) phenyl ] propane, bis [4- (3-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) ] biphenyl, bis [1- (3-aminophenoxy) ] biphenyl, bis [4- (3-aminophenoxy) phenyl ] methane, bis [4- (3-aminophenoxy) phenyl ] ether, bis [4- (3-aminophenoxy) ] benzophenone, 9-bis [4- (3-aminophenoxy) phenyl ] fluorene, 2-bis- [4- (4-aminophenoxy) phenyl ] hexafluoropropane, and, 2, 2-bis- [4- (3-aminophenoxy) phenyl ] hexafluoropropane, 3' -dimethyl-4,4' -diaminobiphenyl, 4' -methylenedi-o-toluidine, 4' -methylenedi-2, 6-xylidine, 4' -methylene-2, 6-diethylaniline, 3' -diaminodiphenylethane, 3' -diaminobiphenyl, 3' -dimethoxybenzidine, 3 "-diamino-p-terphenyl, 4' - [1, 4' -phenylenebis (1-methylethylidene) ] dianiline, 4' - [1, 3-phenylenebis (1-methylethylidene) ] dianiline, a salt thereof, and a salt thereof, Bis (p-aminocyclohexyl) methane, bis (p- β -amino-tert-butylphenyl) ether, bis (p- β -methyl- δ -aminopentyl) benzene, p-bis (2-methyl-4-aminopentyl) benzene, p-bis (1, 1-dimethyl-5-aminopentyl) benzene, 1, 5-diaminonaphthalene, 2, 6-diaminonaphthalene, 2, 4-bis (β -amino-tert-butyl) toluene, 2, 4-diaminotoluene, m-xylene-2, 5-diamine, p-xylene-2, 5-diamine, m-xylene diamine, p-xylene diamine, 2, 6-diaminopyridine, 2, 5-diamino-1, a diamine residue derived from an aromatic diamine compound such as 3, 4-oxadiazole, piperazine, 2 '-methoxy-4, 4' -diaminobenzanilide, 1,3-bis [2- (4-aminophenyl) -2-propyl ] benzene, or 6-amino-2- (4-aminophenoxy) benzoxazole, or a diamine residue derived from an aliphatic diamine compound such as a dimer acid diamine in which both terminal carboxylic acid groups of the dimer acid are substituted with a primary aminomethyl group or an amino group.

The thermal expansion coefficient, storage elastic coefficient, tensile elastic coefficient, and the like can be controlled by selecting the kinds of the tetracarboxylic acid residue and the diamine residue in the non-thermoplastic polyimide, or by selecting the molar ratio of each of two or more kinds of the tetracarboxylic acid residue and the diamine residue when used. In the case where the non-thermoplastic polyimide has a plurality of polyimide structural units, the units may be present in the form of blocks or may be present randomly, but are preferably present randomly from the viewpoint of suppressing variation in-plane Retardation (RO).

Further, it is preferable to use both of the tetracarboxylic acid residue and the diamine residue contained in the non-thermoplastic polyimide as an aromatic group because the dimensional accuracy of the polyimide film in a high-temperature environment can be improved and the amount of change in-plane Retardation (RO) can be reduced.

The imide group concentration of the non-thermoplastic polyimide is preferably 33% or less, and more preferably 32% or more. Here, the "imide group concentration" refers to the imide group (- (CO) in the polyimide₂A value obtained by dividing the molecular weight of-N-) by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 33%, the molecular weight of the resin itself becomes small, and low hygroscopicity is also deteriorated due to the increase of the polar group. By selecting the combination of the acid anhydride and the diamine compound, the orientation of molecules in the non-thermoplastic polyimide is controlled, thereby suppressing an increase in CTE associated with a decrease in the imide group concentration and ensuring low hygroscopicity.

The weight average molecular weight of the non-thermoplastic polyimide is, for example, preferably within a range of 10,000 to 400,000, and more preferably within a range of 50,000 to 350,000. If the weight average molecular weight is less than 10,000, the strength of the film tends to be reduced and the film tends to be brittle. On the other hand, when the weight average molecular weight exceeds 400,000, the viscosity tends to increase excessively, and defects such as film thickness unevenness and streaks tend to occur during coating operation.

From the viewpoint of ensuring the function as a base layer and the transportability during the production and the application of the thermoplastic polyimide, the thickness of the non-thermoplastic polyimide layer 31 is preferably in the range of 6 μm to 100 μm, more preferably in the range of 9 μm to 50 μm. If the thickness of the non-thermoplastic polyimide layer 31 is less than the lower limit, the electrical insulation and handling properties become insufficient, and if it exceeds the upper limit, the productivity is lowered.

From the viewpoint of heat resistance, the glass transition temperature (Tg) of the non-thermoplastic polyimide layer 31 is preferably 280 ℃ or higher.

From the viewpoint of suppressing warpage, the thermal expansion coefficient of the non-thermoplastic polyimide layer 31 is preferably in the range of 1ppm/K to 30ppm/K, preferably in the range of 1ppm/K to 25ppm/K, and more preferably in the range of 15ppm/K to 25 ppm/K.

In addition, other hardening resin components such as plasticizers and epoxy resins, hardening agents, hardening accelerators, coupling agents, fillers, solvents, flame retardants, and the like may be appropriately blended as arbitrary components in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 31. However, it is preferable to use no plasticizer as much as possible because plasticizers contain a large amount of polar groups and may promote diffusion of copper from copper wiring.

Thermoplastic polyimide layer:

the thermoplastic polyimide constituting the thermoplastic polyimide layer 33 contains a tetracarboxylic acid residue and a diamine residue, and preferably contains an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic dianhydride and an aromatic diamine residue derived from an aromatic diamine.

(tetracarboxylic acid residue)

As the tetracarboxylic acid residue used in the thermoplastic polyimide constituting the thermoplastic polyimide layer 33, the same groups as those exemplified as the tetracarboxylic acid residue in the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer can be used.

(diamine residue)

The diamine residue contained in the thermoplastic polyimide constituting the thermoplastic polyimide layer 33 is preferably a diamine residue derived from a diamine compound represented by general formula (B1) to general formula (B7).

[ solution 4]

In the formulae (B1) to (B7), R₁Independently represents a C1-6 monovalent hydrocarbon group or an alkoxy group, and the linking group A independently represents a group selected from-O-, -S-, -CO-, -SO-, -SO₂-、-COO-、-CH₂-、-C(CH₃)₂A divalent radical of-NH-or-CONH-, n₁Independently represent an integer of 0 to 4. However, a portion that overlaps with formula (B2) is removed from formula (B3), and a portion that overlaps with formula (B4) is removed from formula (B5). Here, the term"independently" means a plurality of linking groups A and a plurality of R in one or more than two of the formulae (B1) to (B7)₁Or a plurality of n₁May be the same or different. Further, in the formulae (B1) to (B7), the hydrogen atoms in the terminal two amino groups may be substituted, and for example, may be-NR₂R₃(Here, R is₂、R₃Independently, an optional substituent such as an alkyl group).

The diamine represented by the formula (B1) (hereinafter, sometimes referred to as "diamine (B1)") is an aromatic diamine having two benzene rings. The diamine (B1) is considered to have an increased degree of freedom and high flexibility in the polyimide molecular chain due to the meta position between the amino group directly bonded to at least one benzene ring and the divalent linking group a, and to contribute to improvement in flexibility of the polyimide molecular chain. Therefore, by using the diamine (B1), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-O-, -CH₂-、-C(CH₃)₂-、-CO-、-SO₂-、-S-。

Examples of the diamine (B1) include: 3,3 '-diaminodiphenylmethane, 3' -diaminodiphenylpropane, 3 '-diaminodiphenylsulfide, 3' -diaminodiphenylsulfone, 3 '-diaminodiphenylether, 3,4' -diaminodiphenylmethane, 3,4 '-diaminodiphenylpropane, 3,4' -diaminodiphenylsulfide, 3 '-diaminobenzophenone, (3,3' -diamino) diphenylamine and the like.

The diamine represented by the formula (B2) (hereinafter, sometimes referred to as "diamine (B2)") is an aromatic diamine having three benzene rings. The diamine (B2) is considered to have an increased degree of freedom and high flexibility in the polyimide molecular chain due to the meta position between the amino group directly bonded to at least one benzene ring and the divalent linking group a, and to contribute to improvement in flexibility of the polyimide molecular chain. Therefore, by using the diamine (B2), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-O-.

Examples of the diamine (B2) include: 1, 4-bis (3-aminophenoxy) benzene, 3- [4- (4-aminophenoxy) phenoxy ] aniline, 3- [3- (4-aminophenoxy) phenoxy ] aniline, and the like.

The diamine represented by the formula (B3) (hereinafter, sometimes referred to as "diamine (B3)") is an aromatic diamine having three benzene rings. The diamine (B3) is believed to have an increased degree of freedom and high flexibility in the polyimide molecular chain due to the fact that the two divalent linking groups a directly bonded to one benzene ring are in a meta position with respect to each other, and thus contributes to the improvement of flexibility of the polyimide molecular chain. Therefore, by using the diamine (B3), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-O-.

Examples of the diamine (B3) include: 1,3-bis (4-aminophenoxy) benzene (1,3-bis (4-aminophenoxy) bezene, TPE-R), 1,3-bis (3-aminophenoxy) benzene (1,3-bis (3-aminophenoxy) bezene, APB), 4' - [ 2-methyl- (1, 3-phenylene) dioxy ] dianiline, 4' - [ 4-methyl- (1, 3-phenylene) dioxy ] dianiline, 4' - [ 5-methyl- (1, 3-phenylene) dioxy ] dianiline, and the like.

The diamine represented by the formula (B4) (hereinafter, sometimes referred to as "diamine (B4)") is an aromatic diamine having four benzene rings. The diamine (B4) is considered to have high flexibility by the amino group directly bonded to at least one benzene ring being in the meta position to the divalent linking group a, and to contribute to improvement in flexibility of the polyimide molecular chain. Therefore, by using the diamine (B4), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-O-, -CH₂-、-C(CH₃)₂-、-SO₂-、-CO-、-CONH-。

Examples of the diamine (B4) include: bis [4- (3-aminophenoxy) phenyl ] methane, bis [4- (3-aminophenoxy) phenyl ] propane, bis [4- (3-aminophenoxy) phenyl ] ether, bis [4- (3-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) ] benzophenone, bis [4,4' - (3-aminophenoxy) ] benzanilide, and the like.

The diamine represented by the formula (B5) (hereinafter, sometimes referred to as "diamine (B5)") is an aromatic diamine having four benzene rings. The diamine (B5) is believed to have an increased degree of freedom and high flexibility in the polyimide molecular chain due to the fact that the two divalent linking groups a directly bonded to at least one benzene ring are in a meta position with respect to each other, and thus contributes to the improvement of flexibility of the polyimide molecular chain. Therefore, by using the diamine (B5), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-O-.

Examples of the diamine (B5) include 4- [3- [4- (4-aminophenoxy) phenoxy ] aniline and 4,4' - [ oxybis (3, 1-phenylene) ] dianiline.

The diamine represented by the formula (B6) (hereinafter, sometimes referred to as "diamine (B6)") is an aromatic diamine having four benzene rings. The diamine (B6) is considered to have high flexibility by having at least two ether bonds, and to contribute to improvement in flexibility of the polyimide molecular chain. Therefore, by using the diamine (B6), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-C (CH)₃)₂-、-O-、-SO₂-、-CO-。

Examples of the diamine (B6) include: 2,2-bis [4- (4-aminophenoxy) phenyl ] propane (2,2-bis [4- (4-aminophenoxy) phenyl ] propane, BAPP), bis [4- (4-aminophenoxy) phenyl ] ether (bis [4- (4-aminophenoxy) phenyl ] ether, BAPE), bis [4- (4-aminophenoxy) phenyl ] sulfone (bis [4- (4-aminophenoxy) phenyl ] sulfone, BAPS), bis [4- (4-aminophenoxy) phenyl ] ketone (bis [4- (4-aminophenoxy) phenyl ] ketone, BAPK), and the like.

The diamine represented by the formula (B7) (hereinafter, sometimes referred to as "diamine (B7)") is an aromatic diamine having four benzene rings. The diamine (B7) has a divalent linking group a having high flexibility on each side of the diphenyl skeleton, and therefore is considered to contribute to improvement in flexibility of the polyimide molecular chain. Therefore, by using the diamine (B7), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-O-.

Examples of the diamine (B7) include bis [4- (3-aminophenoxy) ] biphenyl and bis [4- (4-aminophenoxy) ] biphenyl.

The thermoplastic polyimide constituting the thermoplastic polyimide layer 33 preferably contains a diamine residue derived from at least one diamine compound selected from the group consisting of diamines (B1) to diamines (B7) in an amount of 60 parts by mole or more, preferably 60 parts by mole or more and 99 parts by mole or less, more preferably 70 parts by mole or more and 95 parts by mole or less, based on 100 parts by mole of the total diamine residues. Since the diamines (B1) to (B7) have a molecular structure having flexibility, the flexibility of the polyimide molecular chain can be improved and thermoplasticity can be imparted by using at least one diamine compound selected from these in an amount within the above range. If the total amount of the diamines (B1) to (B7) in the raw materials is less than 60 parts by mole based on 100 parts by mole of the total diamine components, the flexibility of the polyimide resin is insufficient, and thus sufficient thermoplasticity cannot be obtained.

Also, as the diamine residue contained in the thermoplastic polyimide constituting the thermoplastic polyimide layer 33, a diamine residue derived from a diamine compound represented by the general formula (a1) is preferable. The diamine compound represented by the formula (a1) [ diamine (a1) ], is as described in the description of the non-thermoplastic polyimide. Since the diamine (a1) has a rigid structure and has an action of imparting an ordered structure to the entire polymer, the dielectric loss tangent and the moisture absorption can be reduced by suppressing the movement of molecules. Further, by using the thermoplastic polyimide as a raw material, a polyimide having low air permeability and excellent long-term heat-resistant adhesion can be obtained.

The thermoplastic polyimide constituting the thermoplastic polyimide layer 33 may contain a diamine residue derived from a diamine (a1) in a range of preferably 1 part by mole or more and 40 parts by mole or less, more preferably 5 parts by mole or more and 30 parts by mole or less. By using the diamine (a1) in an amount within the above range and forming an ordered structure in the entire polymer by utilizing a rigid structure derived from the monomer, a polyimide which is thermoplastic, has low air permeability and hygroscopicity, and is excellent in long-term heat-resistant adhesion can be obtained.

The thermoplastic polyimide constituting the thermoplastic polyimide layer 33 may contain a diamine residue derived from a diamine compound other than the diamine (a1), the diamine (B1) to the diamine (B7) within a range not to impair the effects of the present invention.

The thermal expansion coefficient, the tensile elastic coefficient, the glass transition temperature, and the like can be controlled by selecting the kinds of the tetracarboxylic acid residue and the diamine residue in the thermoplastic polyimide, or by selecting the molar ratio of each of two or more kinds of the tetracarboxylic acid residue and the diamine residue. When the thermoplastic polyimide has a plurality of polyimide structural units, the units may be present in the form of blocks or may be present randomly, but preferably are present randomly.

Further, by using both of the tetracarboxylic acid residue and the diamine residue contained in the thermoplastic polyimide as an aromatic group, the dimensional accuracy of the polyimide film in a high-temperature environment can be improved, and the amount of change in-plane Retardation (RO) can be suppressed.

The imide group concentration of the thermoplastic polyimide is preferably 33% or less, and more preferably 32% or more. Here, the "imide group concentration" refers to the imide group (- (CO) in the polyimide₂A value obtained by dividing the molecular weight of-N-) by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 33%, the molecular weight of the resin itself becomes small, and low hygroscopicity is also deteriorated due to the increase of the polar group. By controlling the molecular orientation of the thermoplastic polyimide by selecting the combination of the diamine compounds, an increase in CTE associated with a decrease in imide group concentration is suppressed, and low hygroscopicity is ensured.

The weight average molecular weight of the thermoplastic polyimide is, for example, preferably within a range of 10,000 to 400,000, and more preferably within a range of 50,000 to 350,000. If the weight average molecular weight is less than 10,000, the strength of the film tends to be reduced and the film tends to be brittle. On the other hand, when the weight average molecular weight exceeds 400,000, the viscosity tends to increase excessively, and defects such as film thickness unevenness and streaks tend to occur during coating operation.

The thermoplastic polyimide constituting the thermoplastic polyimide layer 33 is, for example, an adhesive layer in an insulating resin of a circuit board, and therefore, in order to suppress diffusion of copper, a completely imidized structure is most preferable. However, a part of the polyimide may be amic acid. The imidization ratio can be measured by measuring the infrared absorption spectrum of the polyimide film by a primary reflection ATR method using a Fourier transform infrared spectrophotometer (commercially available product: FT/IR620 manufactured by JEOL Ltd.) at 1015cm^-1Based on the near benzene ring absorber, according to 1780cm^-1The absorbance of C ═ O stretching derived from the imide group (b) was calculated.

From the viewpoint of securing the adhesive function, the thickness of the thermoplastic polyimide layer 33 is preferably in the range of 1 μm or more and 10 μm or less, and more preferably in the range of 1 μm or more and 5 μm or less. When the thickness of the thermoplastic polyimide layer 33 is less than the lower limit, the adhesiveness is insufficient, and when it exceeds the upper limit, the dimensional stability tends to deteriorate.

From the viewpoint of suppressing warpage, the thermal expansion coefficient of the thermoplastic polyimide layer 33 is preferably in the range of 30ppm/K or more, preferably 30ppm/K or more and 100ppm/K or less, and more preferably 30ppm/K or more and 80ppm/K or less.

In addition, in the resin used for the thermoplastic polyimide layer 33, other hardening resin components such as plasticizers and epoxy resins, hardening agents, hardening accelerators, inorganic fillers, coupling agents, fillers, solvents, flame retardants, and the like may be suitably blended as optional components in addition to the polyimide.

The non-thermoplastic polyimide and the thermoplastic polyimide used to form the non-thermoplastic polyimide layer 31 and the thermoplastic polyimide layer 33 can be produced in the same manner as the DDA-based polyimide by: the acid anhydride component and the diamine component are reacted in a solvent to produce a polyamic acid, which is then subjected to ring closure by heating. In the synthesis of the non-thermoplastic polyimide and the thermoplastic polyimide, the acid anhydride and the diamine may be used alone, or two or more kinds may be used in combination. The thermal expansibility, adhesiveness, glass transition temperature, etc. can be controlled by selecting the kind of the acid anhydride and the diamine, or the molar ratio of each of the acid anhydride and the diamine when two or more kinds thereof are used.

< coefficient of thermal expansion >

In the metal-clad laminate 10, the Coefficient of Thermal Expansion (CTE) of the entire resin laminate 20 is preferably 10ppm/K or more, more preferably 10ppm/K or more and 30ppm/K or less, and still more preferably 15ppm/K or more and 25ppm/K or less. If the CTE is less than 10ppm/K or exceeds 30ppm/K, warpage occurs or dimensional stability is lowered. By appropriately changing the combination of raw materials used, the thickness, and the drying/hardening conditions, a polyimide layer having a desired CTE can be produced.

< dielectric loss tangent >

In the metal-clad laminate 10, the dielectric loss tangent (Tan δ) at 10GHz of the entire resin laminate 20 is preferably 0.02 or less, more preferably 0.0005 or more and 0.01 or less, and still more preferably 0.001 or more and 0.008 or less. If the dielectric loss tangent at 10GHz of the entire resin laminate 20 exceeds 0.02, when applied to a circuit board, problems such as loss of an electric signal tend to occur in a transmission path of a high-frequency signal. On the other hand, the lower limit of the dielectric loss tangent at 10GHz of the entire resin laminate 20 is not particularly limited, but physical property control of the insulating resin layer as the circuit board is considered.

< dielectric constant >

In the metal-clad laminate 10, when the resin laminate 20 is used as an insulating resin layer of a circuit board, for example, in order to ensure impedance matching, the dielectric constant at 10GHz is preferably 4.0 or less based on the entire resin laminate 20. If the dielectric constant at 10GHz of the entire resin laminate 20 exceeds 4.0, the dielectric loss increases when applied to a circuit board, and a problem such as loss of an electric signal tends to occur in a transmission path of a high-frequency signal.

[ production of Metal-clad laminate ]

The metal clad laminate 10 can be manufactured, for example, by: resin sheets corresponding to the first transmission loss suppression layer BS1, the second transmission loss suppression layer BS2, the multiple dimensional accuracy maintenance layers PL, and one or more intermediate transmission loss suppression layers BS3 are prepared, and these resin sheets are placed between the first metal layer M1 and the second metal layer M2 and bonded together, and thermocompression bonding is performed.

The metal-clad laminate 10 of the present embodiment obtained in the above manner can be used to manufacture a circuit board such as a single-sided FPC or a double-sided FPC by performing wiring circuit processing by etching or the like of the first metal layer M1 and/or the second metal layer M2.

[ Circuit Board ]

The metal-clad laminate 10 is mainly and effectively used as a circuit board material such as an FPC or a flex-rigid circuit board. The circuit board such as an FPC according to one embodiment of the present invention can be manufactured by patterning one or both of the first metal layer M1 and the second metal layer M2 of the metal-clad laminate 10 by a conventional method to form a wiring layer. Although not shown, the circuit board includes the resin laminate 20 and the wiring layers provided on one or both surfaces of the resin laminate 20, and thus can reduce transmission loss even in high-frequency transmission and has excellent dimensional stability.

[ examples ]

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples at all. In the following examples, unless otherwise specified, various measurements and evaluations are based on the following.

[ measurement of viscosity ]

For the measurement of the viscosity, the viscosity at 25 ℃ was measured using an E-type viscometer (product name: DV-II + Pro, manufactured by Brookfield corporation). The rotational speed was set so that the torque (torque) became 10% to 90%, and after 2 minutes from the start of measurement, the value at which the viscosity became stable was read.

[ measurement of storage modulus of elasticity ]

A resin sheet having a size of 5mm × 20mm was measured at a temperature rise rate of 4 ℃/min and a frequency of 11Hz from 30 ℃ to 400 ℃ using a dynamic viscoelasticity measuring apparatus (DMA: manufactured by UBM, trade name: E4000F).

[ measurement of Coefficient of Thermal Expansion (CTE) ]

A polyimide film having a size of 3mm × 20mm was heated from 30 ℃ to 265 ℃ at a constant heating rate while applying a load of 5.0g using a thermomechanical analyzer (product name: 4000SA manufactured by Bruker Co., Ltd.), and was held at the above temperature for 10 minutes and then cooled at a rate of 5 ℃/minute to obtain an average thermal expansion coefficient (thermal expansion coefficient) from 250 ℃ to 100 ℃.

[ measurement of dielectric constant and dielectric loss tangent ]

The dielectric constant (Dk) and dielectric loss tangent (Df) of the resin sheet at 10GHz were measured using a Vector Network Analyzer (trade name: E8363C, manufactured by Agilent) and an SPDR resonator. Furthermore, the materials used in the assay were at temperature: 24 ℃ to 26 ℃ and humidity: the material was left to stand for 24 hours under a condition of 45 to 55% RH.

[ measurement of dimensional Change Rate ]

The dimensional change rate was measured by the following procedure. First, a 150mm square sample was used, and the dry film resist was exposed and developed at 100mm intervals to form a target for position measurement. The dimensions before etching (normal state) were measured in an environment of 23. + -. 2 ℃ and 50. + -. 5% relative humidity, and copper other than the target of the test piece was removed by etching (liquid temperature 40 ℃ or lower and time 10 minutes or less). The substrate was left standing at a temperature of 23. + -. 2 ℃ and a relative humidity of 50. + -. 5% for 24. + -.4 hours, and then the size after etching was measured. The dimensional change rates of the three portions in the vertical direction and the horizontal direction with respect to the normal state were calculated, and the average value of the dimensional change rates was defined as the dimensional change rate after etching. The dimensional change rate after etching was calculated by the following equation.

Dimensional change after etching (%) - (B-a)/ax100

A: inter-target distance before etching

B: inter-target distance after etching

Then, the test piece was heat-treated in an oven at 250 ℃ for 1 hour, and the distance between the targets was measured at the subsequent positions. The dimensional change rates after etching at three points in the longitudinal direction and the lateral direction were calculated, and the average value of the dimensional change rates after heat treatment was defined as the dimensional change rate after heat treatment. The dimensional change rate after heating was calculated by the following numerical expression.

Percent change in dimension after heating (%) - (C-B)/BX 100

B: inter-target distance after etching

C: heated inter-target distance

[ measurement of surface roughness (Rz; ten-point average roughness) of copper foil ]

A stylus type surface roughness meter (trade name: Sarfukoda (Surfcorder) ET-3000, manufactured by Okawa institute, Ltd.) was used, and the surface roughness was measured in terms of Force (Force): 100 μ N, Speed (Speed): 20 μm, Range (Range): the measurement condition was 800 μm. The surface roughness was calculated by following the Japanese Industrial Standards (JIS) -B0601: 1994, respectively.

The abbreviations used in the synthesis examples represent the following compounds.

BTDA: 3,3',4,4' -benzophenone tetracarboxylic dianhydride

And (3) PMDA: pyromellitic dianhydride

BPDA: 3,3',4,4' -biphenyltetracarboxylic dianhydride

BPADA: 2,2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride

And (3) DAPE: 4,4' -diaminodiphenyl ether

p-PDA: p-phenylenediamine

BAPP: 2,2-bis [4- (4-aminophenoxy) phenyl ] propane

m-TB: 2,2'-dimethyl-4,4' -diaminobiphenyl

TPE-R: 1,3-bis (4-aminophenoxy) benzene

DDA: aliphatic diamine having 36 carbon atoms (manufactured by Croda Japan, Inc., trade name: Priiramine (PRIAMINE)1074, amine number: 205mgKOH/g, mixture of dimer diamines of cyclic structure and chain structure, content of dimer component: 95 wt% or more)

OP 935: aluminum organophosphonate (manufactured by Clariant Japan, trade name: Exxolite OP935)

N-12: dodecanedioic acid dihydrazide

DMAc: n, N-dimethyl acetamide

NMP: n-methyl-2-pyrrolidone

(Synthesis example 1)

312g of DMAc was placed in a reaction vessel which contained a thermocouple and a stirrer and into which nitrogen gas was introduced. In the reaction vessel, 14.67g of DAPE (0.073 mol) was dissolved while stirring in the vessel. Then, 23.13g of BTDA (0.072 mol) was added. Thereafter, stirring was continued for 3 hours, thereby preparing a resin solution a of polyamic acid having a solution viscosity of 2,960 mPas.

(Synthesis example 2)

200g of DMAc was placed in a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen. In the reaction vessel, 1.335g of m-TB (0.0063 mol) and 10.414g of TPE-R (0.0356 mol) were dissolved while stirring in the vessel. Then, 0.932g of PMDA (0.0043 mol) and 11.319g of BPDA (0.0385 mol) were added. Thereafter, stirring was continued for 2 hours, thereby preparing a resin solution b of polyamic acid having a solution viscosity of 1,420 mPas.

(Synthesis example 3)

250g of DMAc was placed in a reaction vessel which included a thermocouple and a stirrer and into which nitrogen gas was introduced. In the reaction vessel, 2.561g of p-PDA (0.0237 mol) and 16.813g of DAPE (0.0840 mol) were dissolved while stirring in the vessel. 18.501g of PMDA (0.0848 mol) and 6.239g of BPDA (0.0212 mol) were then added. Thereafter, stirring was continued for 3 hours to prepare a resin solution c of polyamic acid having a solution viscosity of 29,500 mPas.

(Synthesis example 4)

250g of DMAc was placed in a reaction vessel which included a thermocouple and a stirrer and into which nitrogen gas was introduced. In the reaction vessel, 12.323g of m-TB (0.0580 mol) and 1.886g of TPE-R (0.0064 mol) were dissolved while stirring in the vessel. 8.314g of PMDA (0.0381 mol) and 7.477g of BPDA (0.0254 mol) were then added. Thereafter, stirring was continued for 3 hours, thereby preparing a resin solution d of polyamic acid having a solution viscosity of 31,500 mPas.

(Synthesis example 5)

< preparation of resin solution e for adhesive layer >

A500 mL four-necked flask equipped with a nitrogen inlet, a stirrer, a thermocouple, a Dean Stark trap (Dean Stark trap) and a cooling tube was charged with 44.92g of BTDA (0.139 mol), 75.08g of DDA (0.141 mol), 168g of NMP and 112g of xylene, and mixed at 40 ℃ for 30 minutes to prepare a polyamic acid solution. Heating the polyamic acid solution to 190 ℃, heating and stirring for 4 hours, and removing distilled water and xylene out of the system. Thereafter, the mixture was cooled to 100 ℃ and 112g of xylene was added thereto, followed by stirring and further cooling to 30 ℃ to complete imidization, thereby obtaining a resin solution e for an adhesive layer (solid content: 29.5 wt%).

(Synthesis example 6)

< preparation of resin solution f for adhesive layer >

A polyamic acid solution was prepared in the same manner as in Synthesis example 5, except that 42.51g of BPADA (0.082 mol), 34.30g of DDA (0.066 mol), 6.56g of BAPP (0.016 mol), 208g of NMP and 112g of xylene were used as raw material compositions. The polyamic acid solution was treated in the same manner as in synthetic example 5 to obtain a resin solution f for an adhesive layer (solid content: 30.0 wt%).

Production example 1

< preparation of polyimide film >

The resin solution c of polyamic acid was uniformly applied to one surface of an electrolytic copper foil 1 (thickness 12 μm, Rz: 2.1 μm) so that the cured thickness became about 25 μm, and then heated and dried at 120 ℃ to remove the solvent. Further, the imidization is completed by performing a stepwise heat treatment from 120 ℃ to 360 ℃ within 30 minutes. A polyimide film 1 (thickness: 25 μm, Dk: 3.4, Df: 0.0085, CTE: 16ppm/K, minimum storage modulus of elasticity (100 ℃ C. to 250 ℃ C.) at 2.9GHz) was prepared by etching away the copper foil using an aqueous solution of ferric chloride.

(preparation example 2)

< preparation of polyimide film >

A polyimide film 2 (thickness: 25 μm, Dk: 3.3, Df: 0.0034, CTE: 17ppm/K, minimum storage modulus of elasticity (100 ℃ C. to 250 ℃ C.) at 3.0GHz) was produced in the same manner as in production example 1, except that the resin solution d was used.

(preparation example 3)

< preparation of polyimide film >

The resin solution a was uniformly applied to one surface of the electrolytic copper foil 1 (thickness 12 μm, Rz: 2.1 μm) so that the cured thickness became about 2 μm to 3 μm, and then heated and dried at 120 ℃ to remove the solvent. Then, the resin solution d was uniformly applied thereon so that the thickness after curing became about 21 μm, and then heated and dried at 120 ℃ to remove the solvent. Further, the resin solution a was uniformly applied thereon so that the thickness after curing became about 2 to 3 μm, and then heated and dried at 120 ℃ to remove the solvent. Three polyamic acid layers were formed in the manner described, and then subjected to a stepwise heat treatment from 120 ℃ to 360 ℃ to complete imidization. A polyimide film 3 (thickness: 25 μm, Dk: 3.4, Df: 0.0052, CTE: 21ppm/K, minimum storage modulus of elasticity (100 ℃ C. to 250 ℃ C.) of 2.8GHz) was prepared by etching away the copper foil layer using an aqueous solution of ferric chloride.

Production example 4

< preparation of polyimide film >

The resin solution b was uniformly applied to one surface of the electrolytic copper foil 1 (thickness 12 μm, Rz: 2.1 μm) so that the cured thickness became about 2 μm to 3 μm, and then dried by heating at 120 ℃ to remove the solvent. Then, the resin solution d was uniformly applied thereon so that the thickness after curing became about 21 μm, and then heated and dried at 120 ℃ to remove the solvent. Further, the resin solution b was uniformly applied thereon so that the thickness after curing became about 2 to 3 μm, and then heated and dried at 120 ℃ to remove the solvent. Three polyamic acid layers were formed in the manner described, and then subjected to a stepwise heat treatment from 120 ℃ to 360 ℃ to complete imidization. A polyimide film 4 (thickness: 25 μm, Dk: 3.3, Df: 0.0032, CTE: 23ppm/K, minimum storage modulus of elasticity (100 ℃ C. to 250 ℃ C.) 2.7GHz) was prepared by etching away the copper foil layer using an aqueous solution of ferric chloride.

Preparation example 5

< preparation of resin sheet >

In 169.49g of the resin solution e (solid content: 50g), 1.8g of N-12(0.0036 mol) and 12.5g of OP935 were mixed, and 6.485g of NMP and 19.345g of xylene were added to dilute the mixture to prepare a polyimide varnish 1.

The polyimide varnish 1 was applied to the silicone-treated surface of the release substrate so that the thickness after drying became 25 μm, and then dried by heating at 80 ℃ and peeled from the release substrate to prepare a resin sheet 1. The dielectric constant (Dk) and the dielectric loss tangent (Df) of the resin sheet 1 were 2.7 and 0.0023, respectively.

(preparation example 6)

< preparation of resin sheet >

Resin sheet 2 was prepared in the same manner as in preparation example 6, except that the thickness after drying was 50 μm. The dielectric constant (Dk) and the dielectric loss tangent (Df) of the resin sheet 2 were 2.7 and 0.0023, respectively.

Production example 7

< preparation of resin sheet >

A resin sheet 3 was prepared in the same manner as in production example 6, except that the thickness after drying was 75 μm. The dielectric constant (Dk) and the dielectric loss tangent (Df) of the resin sheet 3 were 2.7 and 0.0023, respectively.

Production example 8

< preparation of resin sheet >

Resin sheet 4 was prepared in the same manner as in preparation example 6, except that the thickness after drying was set to 5 μm. The dielectric constant (Dk) and the dielectric loss tangent (Df) of the resin sheet 4 were 2.7 and 0.0023, respectively.

Preparation example 9

< preparation of resin sheet >

The resin solution f for the adhesive layer was applied to the silicone-treated surface of the release substrate so that the thickness after drying became 25 μm, and then dried by heating at 80 ℃ and peeled from the release substrate, thereby producing a resin sheet 5. The dielectric constant (Dk) and the dielectric loss tangent (Df) of the resin sheet 5 were 2.8 and 0.0028, respectively.

(preparation example 10)

< preparation of resin sheet >

A resin sheet 6 was prepared in the same manner as in preparation example 9, except that the thickness after drying was 50 μm. The dielectric constant (Dk) and the dielectric loss tangent (Df) of the resin sheet 6 were 2.8 and 0.0028, respectively.

[ example 1]

Two pieces of electrolytic copper foil 1, two pieces of resin sheet 1, one piece of resin sheet 2, and two pieces of polyimide film 4 were prepared, and the electrolytic copper foil 1/the resin sheet 1/the polyimide film 4/the resin sheet 2/the polyimide film 4/the resin sheet 1/the electrolytic copper foil 1 were laminated in this order, followed by thermocompression bonding at 160 ℃ and 4MPa for 60 minutes, thereby preparing the metal-clad laminate 1 having both surfaces. The results of evaluating the double-sided metal-clad laminate 1 are as follows.

Post-etching dimensional change rate in the longitudinal (Machine Direction, MD) Direction: -0.05%

Dimensional change rate after etching in the Transverse (TD) Direction: -0.04%

Dimensional change rate after heating in MD direction: -0.03%

Post-heating dimensional change rate in TD direction: 0.03 percent

The resin laminate 1 (thickness: 150 μm) prepared by removing the electrolytic copper foil 1 from the metal-clad laminate 1 by etching had dielectric constants (Dk) and dielectric loss tangents (Df) of 2.9 and 0.0026, respectively. The total thickness of the dimensional accuracy-maintaining layers was 33% of the total thickness of the resin laminate 1.

[ example 2]

Two pieces of electrolytic copper foil 1, two pieces of resin sheet 1, one piece of resin sheet 3, and two pieces of polyimide film 4 were prepared, and the electrolytic copper foil 1/the resin sheet 1/the polyimide film 4/the resin sheet 3/the polyimide film 4/the resin sheet 1/the electrolytic copper foil 1 were laminated in this order, followed by thermocompression bonding at 160 ℃ and 4MPa for 60 minutes, thereby preparing a metal-clad laminate 2 having both surfaces. The results of evaluating the metal-clad double-sided laminate 2 are as follows.

Post-etching dimensional change rate in MD direction: -0.06%

Post-etch dimensional change rate in TD direction: -0.04%

Dimensional change rate after heating in MD direction: -0.04%

Post-heating dimensional change rate in TD direction: 0.04 percent

The dielectric constant (Dk) and the dielectric loss tangent (Df) of the resin laminate 2 (thickness: 175 μm) prepared by removing the electrolytic copper foil 1 from the metal-clad laminates 2 were 2.92 and 0.0026, respectively. The total thickness of the dimensional accuracy maintaining layers is 29% of the entire thickness of the resin laminate 2.

[ example 3]

Two pieces of electrolytic copper foil 1, one piece of resin sheet 1, two pieces of resin sheet 2, and two pieces of polyimide film 4 were prepared, and the electrolytic copper foil 1/the resin sheet 2/the polyimide film 4/the resin sheet 1/the polyimide film 4/the resin sheet 2/the electrolytic copper foil 1 were laminated in this order, followed by thermocompression bonding at 160 ℃ and 4MPa for 60 minutes, thereby preparing the metal-clad laminate 3 having both sides. The results of evaluating the double-sided metal-clad laminate 3 are as follows.

Post-etching dimensional change rate in MD direction: -0.02%

Post-etch dimensional change rate in TD direction: 0.03 percent

Dimensional change rate after heating in MD direction: -0.06%

Post-heating dimensional change rate in TD direction: -0.02%

The dielectric constant (Dk) and the dielectric loss tangent (Df) of the resin laminate 3 (thickness: 175 μm) prepared by removing the electrolytic copper foil 1 from the metal-clad laminate 3 by etching were 2.9 and 0.0026, respectively. The total thickness of the dimensional accuracy maintaining layers is 29% of the entire thickness of the resin laminate 3.

[ example 4]

A metal-clad laminate 4 was produced in the same manner as in example 1, except that the polyimide film 1 was used instead of the polyimide film 4. The metal-clad laminate 4 on both sides was evaluated, and as a result, no problem was found in dimensional change. The dielectric constant (Dk) and the dielectric loss tangent (Df) of the resin laminate 4 (thickness: 150 μm) prepared by removing the electrolytic copper foil 1 from the metal-clad laminate 4 by etching were 2.9 and 0.0044, respectively. The total thickness of the dimensional accuracy maintaining layers is 33% of the entire thickness of the resin laminate 4.

[ example 5]

A metal-clad laminate 5 was produced in the same manner as in example 1, except that the polyimide film 2 was used instead of the polyimide film 4. The metal-clad laminates 5 on both sides were evaluated, and as a result, dimensional changes were not problematic. The resin laminate 5 (thickness: 150 μm) prepared by removing the electrolytic copper foil 1 from the metal-clad laminate 5 by etching had dielectric constants (Dk) and dielectric loss tangents (Df) of 2.9 and 0.0027, respectively. The total thickness of the dimensional accuracy maintaining layers was 33% of the total thickness of the resin laminate 5.

[ example 6]

A metal-clad laminate 6 was produced in the same manner as in example 1, except that the polyimide film 3 was used instead of the polyimide film 4. The metal-clad laminates 6 on both sides were evaluated, and as a result, dimensional changes were not problematic. The dielectric constant (Dk) and the dielectric loss tangent (Df) of the resin laminate 6 (thickness: 150 μm) prepared by removing the electrolytic copper foil 1 from the metal-clad laminate 6 by etching were 2.9 and 0.0033, respectively. The total thickness of the dimensional accuracy maintaining layers was 33% of the total thickness of the resin laminate 6.

[ example 7]

A double-sided metal-clad laminate 7 was produced in the same manner as in example 1, except that the resin sheet 5 was used instead of the resin sheet 1 and the resin sheet 6 was used instead of the resin sheet 2. The metal-clad laminates 7 on both sides were evaluated, and as a result, dimensional changes were not problematic. The resin laminate 7 (thickness: 150 μm) prepared by removing the electrolytic copper foil 1 from the metal-clad laminate 7 by etching had a dielectric constant (Dk) and a dielectric loss tangent (Df) of 3.0 and 0.0029, respectively. The total thickness of the dimensional accuracy maintaining layers was 33% of the total thickness of the resin laminate 7.

[ example 8]

A double-sided metal-clad laminate 8 was produced in the same manner as in example 1, except that the resin sheet 4 was used instead of the resin sheet 1. The metal-clad laminate 8 on both sides was evaluated, and as a result, no problem was found in dimensional change. The resin laminate 8 (thickness: 110 μm) prepared by removing the electrolytic copper foil 1 from the metal-clad laminate 8 by etching had a dielectric constant (Dk) and a dielectric loss tangent (Df) of 3.0 and 0.0027, respectively. The total thickness of the dimensional accuracy maintaining layers is 45% of the entire thickness of the resin laminate 8.

Comparative example 1

Two pieces of electrolytic copper foil 1, two pieces of resin sheet 2, and one piece of polyimide film 1 were prepared, and the electrolytic copper foil 1/the resin sheet 2/the polyimide film 1/the resin sheet 2/the electrolytic copper foil 1 were laminated in this order, followed by thermocompression bonding at 160 ℃ and 4MPa for 60 minutes, thereby preparing a metal-clad laminate 9 having both surfaces. The results of evaluating the double-sided metal-clad laminate 9 are as follows.

Post-etching dimensional change rate in MD direction: 0.02 percent

Post-etch dimensional change rate in TD direction: 0.08 percent

Dimensional change rate after heating in MD direction: -0.10%

Post-heating dimensional change rate in TD direction: -0.05%

The dielectric constant (Dk) and the dielectric loss tangent (Df) of the resin laminate 9 (thickness: 125 μm) prepared by removing the electrolytic copper foil 1 from the metal-clad laminates 9 by etching were 2.8 and 0.0035, respectively. The total thickness of the dimensional accuracy maintaining layers is 20% of the entire thickness of the resin laminate 9.

While the embodiments of the present invention have been described in detail for the purpose of illustration, the present invention is not limited to the embodiments and can be variously modified.

Claims

1. A metal clad laminate comprising:

a first metal layer,

A first transmission loss suppressing layer provided in contact with one side of the first metal layer,

A second metal layer,

A second transmission loss suppressing layer provided in contact with one side of the second metal layer, and

a plurality of resin layers interposed between the first transmission loss suppression layer and the second transmission loss suppression layer, and

a resin laminate formed of the first transmission loss suppression layer, the second transmission loss suppression layer, and the plurality of resin layers,

the resin laminate comprises

At least two or more dimensional accuracy maintaining layers, and

an intermediate transmission loss suppressing layer laminated between the dimensional accuracy maintaining layers, and

satisfies the following conditions i and ii;

condition i: in the first transmission loss suppression layer and the second transmission loss suppression layerDielectric loss tangent is Df₁And Df is the dielectric loss tangent of the dimensional accuracy maintaining layer₂At time, at Df₁＜Df₂A dielectric loss tangent at 10GHz, which is measured by separating the dielectric resonator after humidity conditioning for 24 hours under constant temperature and humidity conditions of 23 ℃ and 50% RH;

condition ii: the total thickness of the dimensional accuracy-maintaining layers is in the range of 25% to 60% of the total thickness of the resin laminate.

2. The metal-clad laminate according to claim 1, wherein the dimensional accuracy maintaining layer is a low thermal expansion polyimide layer having a minimum value of a storage elastic coefficient in a temperature region of 100 ℃ to 250 ℃ in a range of 1.0GPa to 8.0GPa and a thermal expansion coefficient in a range of 15ppm/K to 25 ppm/K.

3. The metal-clad laminate according to claim 1 or 2, wherein the resin constituting the first transmission loss suppression layer and the second transmission loss suppression layer is a polyimide obtained by reacting an acid anhydride component with a diamine component, and contains 50 parts by mole or more of dimer diamine in which both terminal carboxylic acid groups of dimer acid are substituted with primary aminomethyl groups or amino groups, relative to 100 parts by mole of the total amount of the diamine component.

4. A circuit substrate, comprising:

a first wiring layer,

A first transmission loss suppressing layer provided in contact with one side of the first wiring layer,

A second wiring layer,

A second transmission loss suppressing layer provided in contact with one side of the second wiring layer, and

the resin laminate comprises

At least two or more dimensional accuracy maintaining layers, and

satisfies the following conditions i and ii;

condition i: the dielectric loss tangent of the first transmission loss suppression layer and the second transmission loss suppression layer is Df₁And Df is the dielectric loss tangent of the dimensional accuracy maintaining layer₂At time, at Df₁＜Df₂A dielectric loss tangent at 10GHz, which is measured by separating the dielectric resonator after humidity conditioning for 24 hours under constant temperature and humidity conditions of 23 ℃ and 50% RH;