TW202112912A - Polyimide film, metal-clad laminate and circuit board featuring low dielectric loss tangent and excellent long-term heat-resistant adhesiveness - Google Patents

Abstract

The present invention provides a polyimide film, which can achieve both low dielectric loss tangent and excellent long-term heat-resistant adhesiveness. Even if it is repeatedly exposed to a high-temperature environment, the adhesiveness with a metal layer is not easily reduced . A polyimide film having a non-thermoplastic polyimide layer and a thermoplastic polyimide layer, and the polyimide film satisfies the following content: (i) the thermal expansion coefficient is 10 ppm/K-30 ppm/K (Ii) The oxygen transmission rate is 5.5×10 ^-14 mol/(m ² ･s･Pa) or less; (iii) Compared with all the monomers composed of non-thermoplastic polyimide and thermoplastic polyimide The ratio of all monomer residues derived from body composition to monomer residues having a biphenyl skeleton is 50 mol% or more.

Description

Polyimide film, metal-clad laminate and circuit substrate

The invention relates to a polyimide film, a metal-clad laminate and a circuit substrate.

Polyimide resin has the characteristics of high insulation, dimensional stability, easy formability, light weight, etc., so it is widely used in electronics, electrical equipment, or electronic parts as a material for circuit boards and the like. In particular, in recent years, with the advancement of high performance and high functionality of electrical and electronic equipment, high-speed transmission of information is required, and parts or members used in these are also required to cope with high-speed transmission. Regarding the polyimide materials used for such applications, attempts are being made to achieve low dielectric constant and low dielectric loss tangent in order to have electrical characteristics that can cope with high-speed transmission.

Most of the existing technologies related to the low dielectric constant/low dielectric loss tangent of polyimide materials are mainly related to low dielectric constant/low dielectric loss tangent resins (fluorine-based resins, liquid crystal polymers, etc.) Multi-layered, or low-dielectric constant/low-dielectric loss tangent filler blending with different kinds of materials, porosity, introduction of ester structure, etc. However, with regard to composite or porous formation, there are problems such as reduction in workability, and the technology of introducing an ester structure has a problem that it cannot be used in large quantities due to the reduction in membrane strength.

In addition, Patent Document 1 and Patent Document 2 propose a polyimide film that can be applied to circuit boards for high-frequency applications by studying the structure of the raw material monomer of polyimide to improve the dielectric properties. .

On the other hand, in recent years, the use of circuit boards in environments exceeding 150°C has also begun to be assumed. For example, flexible printed circuit boards (Flexible Printed Circuit (FPC)) used in automotive electronic equipment are sometimes repeatedly exposed to a high temperature environment of about 150°C. In addition, in devices other than in-vehicle electronic equipment, such as notebook personal computers or supercomputers with a central processing unit (CPU) capable of high-speed processing, in order to achieve further miniaturization and weight reduction, flexible The situation of sexual printed circuit boards is also gradually increasing. In this type of device, the flexible printed circuit board is repeatedly exposed to high-temperature environments due to the heat generated by the CPU. The representative main cause of the deterioration of the flexible printed circuit board due to use in a high-temperature environment is the floating or peeling of the wiring layer due to the decrease in adhesion between the wiring layer and the insulating resin layer.

Based on this background, it is believed that flexible printed circuit boards are expected to require both low dielectric loss tangent and heat-resistant adhesion (maintenance of peel strength retention) under high-temperature environments in the future. In particular, the requirements will be higher due to changes in the use environment. In the past, heat-resistant adhesiveness was maintained for a longer period of time. [Prior Art Literature] [Patent Literature]

[Patent Document 1] WO 2017/159274 [Patent Document 2] WO 2018/061727

[The problem to be solved by the invention] Therefore, the object of the present invention is to provide a polyimide film, which can achieve both low dielectric loss tangent and excellent long-term heat-resistant adhesion, even if repeatedly exposed to a high-temperature environment, adhesion to the metal layer The connection is not easy to decrease. [Technical means to solve the problem]

The inventors of the present invention conducted diligent studies and found that in the polyimide constituting the polyimide layer, the content ratio of the monomer residues having a biphenyl skeleton is increased, thereby making it possible to have a multi-layer polyimide layer. The low dielectric loss tangent of the polyimide film of the amine layer and the excellent long-term heat-resistant adhesiveness brought about by the suppression of oxygen transmission rate have completed the present invention.

That is, the polyimide film of the present invention has a non-thermoplastic polyimide layer and a thermoplastic polyimide layer, the non-thermoplastic polyimide layer includes a non-thermoplastic polyimide, and the thermoplastic polyimide layer It is laminated on at least one side of the non-thermoplastic polyimide layer and includes thermoplastic polyimide. The polyimide film of the present invention is characterized by satisfying the following conditions (i) to (iii). (I) The coefficient of thermal expansion is within the range of 10 ppm/K to 30 ppm/K. (Ii) The oxygen permeability is 5.5×10 ^-14 mol/(m ² ･s･Pa) or less. (Iii) With respect to all monomer residues derived from all monomer components constituting the non-thermoplastic polyimide and the thermoplastic polyimide, it has a biphenyl skeleton calculated by the following formula (1) The ratio of monomer residues is 50 mol% or more.

…（1）[Numerical formula 1]

…(1)

In formula (1), M _i is a monomer residue having a biphenyl skeleton among all monomer residues derived from all monomer components in the polyimide layer constituting the i-th layer of polyimide layer. group share ratio (units: mol%), L _i is the i-th layer thickness of polyimide layer (unit: μm), L is the thickness of the polyimide film (unit: μm), n is 2 The above integer.

The polyimide film of the present invention may be a polyimide film that satisfies the above-mentioned conditions (i) to (iii) and further satisfies the following condition (iv). (Iv) Among all monomer residues derived from all monomer components in the thermoplastic polyimide, the ratio of monomer residues having a biphenyl skeleton is 30 mol% or more.

The overall thickness of the polyimide film of the present invention may be in the range of 30 μm to 60 μm. In this case, the ratio T2/T1 of the total thickness T2 of the thermoplastic polyimide layer to the overall thickness T1 of the polyimide film may be 0.17 or less.

The metal-clad laminate of the present invention is a metal-clad laminate including an insulating resin layer and a metal layer provided on at least one surface of the insulating resin layer. Furthermore, the metal-clad laminate of the present invention is characterized in that the insulating resin layer has a thermoplastic polyimide layer in contact with the surface of the metal layer and an indirectly laminated non-thermoplastic polyimide layer, and contains all Any of the polyimide films mentioned above.

The circuit board of the present invention is a circuit board including an insulating resin layer and a wiring layer provided on at least one surface of the insulating resin layer. Furthermore, the circuit board of the present invention is characterized in that the insulating resin layer has a thermoplastic polyimide layer in contact with the wiring layer and an indirectly laminated non-thermoplastic polyimide layer, and contains any of the above-mentioned polyimide layers. Imine film. [Effects of the invention]

In the polyimide film of the present invention, by setting the content rate of the monomer residue having a biphenyl skeleton to 50 mol% or more, the oxygen transmission rate is suppressed, and low dielectric loss tangent and long-term heat-resistant adhesiveness are both achieved The improvement. Therefore, by using the polyimide film of the present invention as a circuit board material, it is possible to provide a device that can cope with high-speed transmission and can maintain adhesion to the metal layer for a long time even in a use environment that is repeatedly exposed to a high-temperature environment. Circuit board.

Next, an embodiment of the present invention will be described.

[Polyimide film] The polyimide film of one embodiment of the present invention is a polyimide film having a non-thermoplastic polyimide layer and a thermoplastic polyimide layer, the non-thermoplastic polyimide film The layer includes a non-thermoplastic polyimide, and the thermoplastic polyimide is laminated on at least one side of the non-thermoplastic polyimide layer and includes a thermoplastic polyimide. Here, the so-called "non-thermoplastic polyimide" means that the memory elastic modulus at 30°C measured with a dynamic viscoelasticity measuring device (Dynamic Mechanical Analyzer (DMA)) is 1.0× ^{A polyimide having a memory elastic modulus of 1.0×10 8} Pa or more in a temperature range of 10 ⁹ Pa or more and a glass transition temperature of +30° C. or less. The so-called "thermoplastic polyimide" means that the memory elastic modulus at 30°C measured with a dynamic viscoelasticity measuring device (DMA) is 1.0×10 ⁹ Pa or more and the glass transition temperature is within +30°C Polyimide whose memory elastic modulus in the temperature range is less than 1.0×10 ⁸ Pa.

1 and 2 show structural examples of the polyimide film of this embodiment. The polyimide film 100 shown in FIG. 1 has a two-layer structure with a thermoplastic polyimide layer 120A in a single area layer of the non-thermoplastic polyimide layer 110. The polyimide film 101 shown in FIG. 2 has a three-layer structure with a thermoplastic polyimide layer 120A on a single area of the non-thermoplastic polyimide layer 110 and a thermoplastic polyimide layer 120B on the other area. Shape. In addition, the polyimide film of the present embodiment is not limited to the laminated structure illustrated in FIGS. 1 and 2, and may include four or more polyimide layers, for example.

The resin component of the non-thermoplastic polyimide layer 110 preferably contains a non-thermoplastic polyimide, and the resin component of the thermoplastic polyimide layers 120A and 120B preferably contains a thermoplastic polyimide. When the polyimide films 100, 101 and metal foil are laminated to form a metal-clad laminate, the metal foil may be laminated on one side or both sides of the thermoplastic polyimide layers 120A, 120B.

In addition, both non-thermoplastic polyimine and thermoplastic polyimine contain acid dianhydride residues and diamine residues as "monomer residues". The "acid dianhydride residue" refers to a tetravalent group derived from tetracarboxylic dianhydride, and the so-called "diamine residue" refers to a divalent group derived from a diamine compound.

In the polyimide films 100 and 101 of this embodiment, the non-thermoplastic polyimide layer 110 constitutes a low thermal expansion polyimide layer, and the thermoplastic polyimide layers 120A and 120B constitute a high thermal expansion polyimide layer. Imine layer. The low thermal expansion polyimide layer means that the coefficient of thermal expansion (CTE) is preferably in the range of 1 ppm/K or more and 25 ppm/K, more preferably 3 ppm/K or more and 25 ppm/K. Polyimide layer in the range below K. In addition, the highly thermally expandable polyimide layer means that the CTE is preferably 35 ppm/K or more, more preferably 35 ppm/K or more and 80 ppm/K or less, and still more preferably 35 ppm/K or more and 70 ppm/K. Polyimide layer in the range of ppm/K or less. By appropriately changing the combination of the raw materials used, the thickness, and the drying/curing conditions, a polyimide layer having a desired CTE can be produced.

The polyimide films 100 and 101 of this embodiment satisfy the following conditions (i) to (iii). (I) The coefficient of thermal expansion is within the range of 10 ppm/K to 30 ppm/K. Regarding the polyimide films 100 and 101 of the present embodiment, when used as an insulating resin layer of a circuit board, for example, in order to prevent warpage or decrease in dimensional stability, what is important is the thermal expansion coefficient of the entire film ( CTE) is within the range of 10 ppm/K or more and 30 ppm/K or less, preferably within the range of 10 ppm/K or more and 25 ppm/K or less, and more preferably 15 ppm/K to 25 ppm/K In the range. If the CTE is less than 10 ppm/K or more than 30 ppm/K, warpage or reduced dimensional stability will occur.

(Ii) The oxygen permeability is 5.5×10 ^-14 mol/(m ² ･s･Pa) or less. By controlling the oxygen transmission rate of the polyimide film 100, 101 to 5.5×10 ^-14 mol/(m ² ･s･Pa) or less, for example, when used as an insulating resin layer of a circuit board, even if it is repeated It can also maintain the adhesion to the wiring layer for a long period of time when exposed to a high-temperature environment, and can obtain excellent long-term heat-resistant adhesion. When the oxygen permeability of the polyimide films 100 and 101 exceeds 5.5×10 ^-14 mol/(m ² ･s･Pa), for example, the insulating resin layer used as a circuit board and repeatedly exposed to high temperature In this case, oxygen permeating through the insulating resin layer promotes oxidation of the wiring layer, and the adhesion between the wiring layer and the insulating resin layer is reduced.

(Iii) With respect to all monomer residues derived from all monomer components constituting non-thermoplastic polyimide and thermoplastic polyimide, the monomer residue having a biphenyl skeleton calculated by the following formula (1) The ratio of groups (hereinafter, sometimes referred to as "biphenyl skeleton-containing residues") is 50 mol% or more.

…（1）[Numerical formula 2]

…(1)

In the formula (1), M _i is the total monomer residue derived from all the monomer components in the polyimide layer constituting the i-th layer of polyimide layer, the residue containing the biphenyl skeleton the proportion (unit: mol%), L _i is the i-th layer thickness of polyimide layer (unit: μm), L is the thickness of the polyimide film (unit: μm), n is 2 or more Integer.

With respect to all monomer residues derived from all monomer components of polyimine constituting polyimide films 100 and 101, the ratio of residues containing biphenyl skeleton calculated by formula (1) is 50 mol % Or more, it is easy to form an ordered structure in the entire polymer due to the rigid structure derived from the monomer, thereby reducing the oxygen permeability, and suppressing the movement of molecules to reduce the dielectric loss tangent. If the ratio of residues containing a biphenyl skeleton is less than 50 mol%, the dielectric loss tangent is not sufficiently reduced. In addition, if the thickness of the polyimide film is reduced, the oxygen permeability will not be sufficiently reduced. Therefore, for example, when used in a circuit board, the long-term heat-resistant adhesiveness is insufficient, and it is difficult to adapt to high-speed transmission. From such a viewpoint, the ratio of residues containing a biphenyl skeleton calculated by the formula (1) is preferably 60 mol% or more, and more preferably 65 mol% or more. On the other hand, in order to maintain the physical properties required for the polyimide film used as a circuit board material, the ratio of the residues containing the biphenyl skeleton calculated by the formula (1) is preferably set to 80 mol% or less.

Here, as shown in the following formula (a), the biphenyl skeleton is a skeleton in which two phenyl groups are single-bonded. Therefore, the residue containing a biphenyl skeleton includes, for example, a biphenyldiyl group, a biphenyltetrayl group, and the like. The aromatic ring contained in these residues may have arbitrary substituents. As a representative example of the biphenyldiyl group, a group represented by the following formula (b) can be cited. As a representative example of the biphenyltetrayl group, a group represented by the following formula (c) can be cited. Furthermore, in biphenyldiyl and biphenyltetrayl, the bonding bond in the aromatic ring is not limited to the position shown in formula (b) and formula (c). In addition, as described above, in these residues The aromatic ring contained may have any substituent.

[化1]

The residue containing the biphenyl skeleton is a structure derived from a raw material monomer, and can be derived from an acid dianhydride or a diamine compound.

As a representative example of an acid dianhydride residue having a biphenyl skeleton, 3,3',4,4'-biphenyl tetracarboxylic dianhydride (3,3',4,4'-biphenyl tetracarboxylic dianhydride, BPDA), 2,3',3,4'-biphenyltetracarboxylic dianhydride, 4,4'-bisphenol-bis(trimellitic anhydride) and other acid dianhydride derived residues. Among these, in particular, acid dianhydride residues derived from BPDA (hereinafter, also referred to as "BPDA residues") are easy to form an ordered structure of the polymer, and can inhibit the movement of molecules to increase the dielectric loss tangent or Hygroscopicity is reduced, which is preferable. In addition, the BPDA residue can impart self-supporting properties to the gel film of polyimide, which is a precursor of polyimide.

As a representative example of a diamine compound having a biphenyl skeleton, a diamine compound having only two aromatic rings can be cited, and examples include: 2,2'-dimethyl-4,4'-diaminobiphenyl (2 ,2'-dimethyl-4,4'-diamino biphenyl, m-TB), 2,2'-diethyl-4,4'-diamino biphenyl (2,2'-diethyl-4,4' -diamino biphenyl, m-EB), 2,2'-diethoxy-4,4'-diamino biphenyl (2,2'-diethoxy-4,4'-diamino biphenyl, m-EOB), 2,2'-dipropoxy-4,4'-diamino biphenyl (2,2'-dipropoxy-4,4'-diamino biphenyl, m-POB), 2,2'-di-n-propyl -4,4'-diamino biphenyl (2,2'-di-n-propyl-4,4'-diamino biphenyl, m-NPB), 2,2'-divinyl-4,4'- Diamino biphenyl (2,2'-divinyl-4,4'-diamino biphenyl, VAB), 4,4'-diamino biphenyl, 4,4'-diamino-2,2'-bis (Trifluoromethyl)biphenyl (4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, TFMB) etc. The residual genes derived from these diamine compounds have a rigid structure and have the effect of imparting an ordered structure to the entire polymer. By containing residues derived from these diamine compounds, a polyimide with low oxygen permeability and low hygroscopicity can be obtained, and the moisture inside the molecular chain can be reduced, so that the dielectric loss tangent can be reduced.

The polyimide films 100 and 101 of the present embodiment preferably satisfy the following condition (iv) in addition to the conditions (i) to (iii) described above. (Iv) Among all monomer residues derived from all monomer components in the thermoplastic polyimide, the ratio of residues containing a biphenyl skeleton is 30 mol% or more. Among all the monomer residues constituting the thermoplastic polyimide, the ratio of the residues containing the biphenyl skeleton is 30 mol% or more, so that the rigid structure derived from the monomer forms the whole polymer Order structure, therefore, although thermoplastic, low oxygen permeability and hygroscopicity, excellent long-term heat-resistant adhesion, and low dielectric loss tangent can be obtained. Furthermore, in the case where the non-thermoplastic polyimide layer 110 has thermoplastic polyimide layers 120A, 120B on both sides, as long as any one of the thermoplastic polyimide layers 120A, 120B satisfies the above condition (iv) It is sufficient, but it is preferable that both of the thermoplastic polyimide layers 120A and 120B satisfy the above-mentioned condition (iv).

＜Thickness＞ The overall thickness T1 of the polyimide films 100 and 101 of the present embodiment can be set within a predetermined range according to the purpose of use, for example, it is preferably within a range of 30 μm to 60 μm, and more preferably within a range of 35 μm to 50 μm. In the range. If the thickness T1 does not satisfy the lower limit, it is difficult to sufficiently reduce the oxygen permeability, and in the case of repeated exposure to high temperatures, the adhesion between the wiring layer and the insulating resin layer may decrease. On the other hand, if the thickness T1 exceeds the upper limit, the following problems occur: when the polyimide film is bent, cracks and breakage occur.

In addition, the total thickness T2 of the thermoplastic polyimide layers 120A, 120B (here, T2 means T2A in FIG. 1 and T2A+T2B in FIG. 2) relative to the overall thickness of the polyimide films 100, 101 The ratio T2/T1 of T1 is preferably 0.17 or less, and more preferably in the range of 0.10 to 0.15. If the value of the ratio is greater than 0.17, the oxygen permeability becomes large, and it is difficult to reduce the dielectric loss tangent. Therefore, for example, when used in a circuit board, the long-term heat-resistant adhesiveness is insufficient, and it is difficult to adapt to high-speed transmission. The lower limit of the ratio T2/T1 is not particularly limited. The reason is that the smaller the ratio T2/T1, the easier it is to reduce the oxygen transmission rate and dielectric loss tangent. Among them, the smaller the ratio T2/T1, the smaller the proportion of the thickness of the thermoplastic polyimide layers 120A, 120B. Therefore, the lower limit of the ratio T2/T1 is used to ensure the adhesion of the polyimide films 100, 101 and the wiring layer. The value of the connection reliability is preferably about 0.02, for example.

Furthermore, the thickness T3 of the non-thermoplastic polyimide layer 110 can be set in a predetermined range according to the purpose of use, for example, it is preferably in the range of 25 μm to 49 μm, and more preferably in the range of 30 μm to 49 μm. . If the thickness T3 does not satisfy the lower limit, the improvement effect of the dielectric properties of the polyimide films 100 and 101 becomes smaller, and the oxygen permeability becomes larger. In the case of repeated exposure to high temperatures, there is a wiring layer There is a concern that the adhesiveness with the insulating resin layer will decrease.

Generally speaking, polyimide can be produced by reacting an acid dianhydride and a diamine compound in a solvent to generate polyimide acid and then heating and ring-closing (imidization). For example, the acid dianhydride and the diamine compound are dissolved in an organic solvent at approximately equal moles, and the polymerization reaction is carried out by stirring at a temperature in the range of 0°C to 100°C for 30 minutes to 24 hours. Polyamide acid which is the precursor of imine. During the reaction, the reaction components are dissolved so that the generated precursor is in the range of 5% by weight to 30% by weight, preferably in the range of 10% by weight to 20% by weight, in the organic solvent. As the organic solvent used in the polymerization reaction, for example, N,N-dimethyl formamide (N,N-dimethyl formamide, DMF), N,N-dimethylformamide (N,N- dimethyl acetamide, DMAc), N,N-diethyl acetamide, N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone, NMP), 2-butanone, dimethyl sulfoxide (Dimethyl Sulfoxide) , DMSO), hexamethylphosphamide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triethylene glycol dimethyl Ether, cresol, etc. These solvents may be used in combination of two or more types, and aromatic hydrocarbons such as xylene and toluene may also be used in combination. In addition, the amount of such an organic solvent used is not particularly limited, but it is preferably adjusted so that the concentration of the polyamide acid solution obtained by the polymerization reaction becomes about 5 to 30% by weight.

The synthesized polyamide acid is usually advantageously used as a reaction solvent solution, but it can be concentrated, diluted or replaced with other organic solvents as necessary. In addition, polyamide acid is generally excellent in solvent solubility, and therefore can be advantageously used. The viscosity of the polyamide acid solution is preferably in the range of 500 cps to 100,000 cps. If it is out of the above range, defects such as uneven thickness and streaks are likely to occur in the film during coating work by a coater or the like. The method for imidizing polyamide is not particularly limited. For example, heat treatment such as heating in the solvent and under temperature conditions in the range of 80°C to 400°C for 1 hour to 24 hours can be suitably used. .

Next, the non-thermoplastic polyimide and the thermoplastic polyimide will be described in more detail.

＜Non-thermoplastic polyimide＞ In the polyimide films 100 and 101, the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 110 contains acid dianhydride residues and diamine residues. The non-thermoplastic polyimide preferably contains 60 mol or more of biphenyl skeleton-containing residues in all monomer residues derived from all monomer components, and more preferably 70 mol or more of residues. By setting the biphenyl skeleton-containing residues in the non-thermoplastic polyimide to be 60 mol or more, the biphenyl skeleton-containing residues in the entire polyimide film 100 and 101 can be increased. The content ratio of, reduces the oxygen transmission rate, and realizes the low dielectric loss tangent.

(Acid dianhydride residue) The non-thermoplastic polyimide preferably contains 35 mol or more of acid dianhydride residues having a biphenyl skeleton in all acid dianhydride residues, and more preferably contains 50 mol or more of acid dianhydride residues. It is more preferable to contain the biphenyltetrayl represented by the formula (c) in the above-mentioned amount.

In addition to the acid dianhydride residue having the biphenyl skeleton, the non-thermoplastic polyimine may also contain the residue of the acid dianhydride that is generally used as a raw material for polyimine within the range that does not impair the effect of the invention. . Examples of such acid dianhydride residues include pyromellitic dianhydride (PMDA) and 1,4-phenylene bis(trimellitic acid monoester) dianhydride (1,4-phenylene dianhydride). bis(trimellitic acid monoester)dianhydride, TAHQ), 2,3,6,7-naphthalene tetracarboxylic dianhydride (2,3,6,7-naphthalene tetracarboxylic dianhydride, NTCDA), 3,3',4,4' -Diphenyl tetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 2,3,3 ',4'-benzophenone tetracarboxylic dianhydride or 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,3',3,4'-diphenyl ether tetra Carboxylic dianhydride, bis(2,3-dicarboxyphenyl) ether dianhydride, 3,3``,4,4''-p-terphenyltetracarboxylic dianhydride, 2,3,3'',4 ''-P-terphenyltetracarboxylic dianhydride or 2,2'',3,3''-p-terphenyltetracarboxylic dianhydride, 2,2-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) dianhydride or bis(3,4-dicarboxyphenyl) dianhydride, 1,1-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-tetra Carboxylic dianhydride or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride, 2,2-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, 2,3,8,9-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, cyclopentane-1 ,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2 ,3,4,5-tetracarboxylic dianhydride, 4,4'-bis(2,3-dicarboxyphenoxy) diphenylmethane dianhydride, ethylene glycol bistrimellitic anhydride and other aromatic tetracarboxylic acid bis Anhydride-derived acid dianhydride residue.

(Diamine residue) The non-thermoplastic polyimide preferably contains 70 moles or more of diamine residues having a biphenyl skeleton in all diamine residues, and more preferably contains 85 moles or more of diamine residues. It is more preferable to contain the biphenyldiyl group represented by the formula (b) in the above-mentioned amount. The biphenyldiyl group represented by the formula (b) has a rigid structure and has the effect of imparting an ordered structure to the entire polymer, thereby reducing the oxygen permeability and suppressing the movement of molecules to reduce the dielectric loss tangent.

In addition to the diamine residue having a biphenyl skeleton, the non-thermoplastic polyimine may also contain the residue of a diamine compound that is generally used as a raw material of the polyimide within a range that does not impair the effect of the invention. As such a diamine residue, for example, 1,4-diaminobenzene (p-Phenylenediamine (p-Phenylenediamine, p-PDA)), 4-aminophenyl-4'-aminobenzyl Esters (4-amino phenyl-4'-amino benzoate, APAB), 3,3'-diaminodiphenylmethane, 3,3'-diaminodiphenylpropane, 3,3'-diamine Diphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,4' -Diaminodiphenylmethane, 3,4'-diaminodiphenylpropane, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, ( 3,3'-bisamino)diphenylamine, 1,4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]aniline, 3-[3-(4-aminophenoxy)phenoxy]aniline, 1,3-bis(4-aminophenoxy)benzene (1,3-bis(4-aminophenoxy)benzene, TPE- R), 1,3-bis(3-aminophenoxy)benzene (1,3-bis(3-aminophenoxy)benzene, APB), 4,4'-[2-methyl-(1,3- Phenylene) bisoxy] bisaniline, 4,4'-[4-methyl-(1,3-phenylene) bisoxy] bisaniline, 4,4'-[5-methyl-( 1,3-phenylene)bisoxy]bisaniline, bis[4,4'-(3-aminophenoxy)]benzaniline, 4-[3-[4-(4-amino) Phenoxy)phenoxy]phenoxy]aniline, 4,4'-[oxybis(3,1-phenyleneoxy)]bisaniline, bis[4-(4-aminophenoxy) ) Phenyl] ether (bis[4-(4-aminophenoxy)phenyl]ether, BAPE), bis[4-(4-aminophenoxy)phenyl] 碸 (bis[4-(4-aminophenoxy)phenyl ]sulfone, BAPS), bis[4-(4-aminophenoxy)phenyl]ketone (BAPK), 2,2-bis[4-(3 -Aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (2,2-bis[4-(4-aminophenoxy)phenyl]propane , BAPP), bis[4-(3-aminophenoxy)phenyl] ash, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminobenzene) Oxy)phenyl]ether, bis[4-(3-aminophenoxy)]benzophenone, 9,9-bis[4-(3-aminophenoxy)phenyl]fluorene, 2 ,2-Bis-[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis-[4-(3-aminophenoxy) Phenyl]hexafluoropropane, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-methylenebis-o-toluidine, 4,4'-methylenebis -2,6-dimethylaniline, 4,4'-methylene-2,6-diethylaniline, 3,3'-diaminodiphenylethane, 3,3'-diaminodi Benzene, 3,3'-dimethoxybenzidine, 3,3''-diamino-p-terphenyl, 4,4'-[1,4-phenylene bis(1-methylethylene )] bisaniline, 4,4'-[1,3-phenylene bis(1-methylethylene)] bisaniline, 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-xylylene diamine, p-xylylene diamine, 2,6- Diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, pyrazine, 2'-methoxy-4,4'-diamino Benzalaniline, 4,4'-diaminobenzaniline, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-bis[2- (4-aminophenyl)-2-propyl)benzene, 1,4-bis(4-aminophenoxy)-2,5-di-tert-butylbenzene, 6-amino-2-( 4-aminophenoxy)benzoxazole, 2,6-diamino-3,5-diethyltoluene, 2,4-diamino-3,5-diethyltoluene, 2,4 -Diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, bis(4-amino-3-ethyl-5-methylphenyl)methane and other aromatics Diamine residues derived from diamine compounds; diamines derived from aliphatic diamine compounds such as dimer acid diamines in which the two terminal carboxylic acid groups of the dimer acid are substituted by a primary amino methyl group or an amine group Residues etc.

In the non-thermoplastic polyimide, by selecting the types of the acid dianhydride residues and diamine residues, or the respective molar ratios when two or more acid dianhydride residues or diamine residues are used, It can control oxygen permeability, dielectric properties, thermal expansion coefficient, memory elastic modulus, tensile elastic modulus, etc. In addition, in the non-thermoplastic polyimide, when it has a plurality of polyimine structural units, it may exist in the form of a block or may exist randomly, but it is preferably present randomly.

The non-thermoplastic polyimide preferably contains an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic dianhydride and an aromatic diamine residue derived from an aromatic diamine. By making the acid dianhydride residue and the diamine residue contained in the non-thermoplastic polyimide both an aromatic group, the dimensional accuracy of the polyimide films 100 and 101 in a high-temperature environment can be improved.

The concentration of the non-thermoplastic polyimide group is preferably 33% by weight or less. Here, the "imine group concentration" refers to _{a value obtained by dividing the molecular weight of the amide group (-(CO) 2} -N-) in the polyimide by the molecular weight of the entire structure of the polyimide. If the concentration of the imine group exceeds 33% by weight, the hygroscopicity increases due to the increase of the polar group. By selecting the combination of the acid dianhydride and the diamine compound to control the orientation of the molecules in the non-thermoplastic polyimide, it is possible to suppress the increase in CTE accompanying the decrease in the concentration of the imine group, thereby ensuring low hygroscopicity .

The weight average molecular weight of the non-thermoplastic polyimide is, for example, preferably in the range of 10,000 to 400,000, and more preferably in the range of 50,000 to 350,000. If the weight average molecular weight is less than 10,000, the strength of the film will decrease and it will tend to become brittle. On the other hand, if the weight average molecular weight exceeds 400,000, the viscosity increases excessively, and defects such as uneven film thickness and streaks tend to occur during the coating operation.

＜Thermoplastic polyimide＞ In the polyimide films 100 and 101, the thermoplastic polyimide constituting the thermoplastic polyimide layers 120A and 120B contains acid dianhydride residues and diamine residues. As in the aforementioned condition (iv), the thermoplastic polyimide preferably contains 30 moles or more of residues containing a biphenyl skeleton in all monomer residues derived from all monomer components, and more preferably 40 moles. the above. By setting the residues containing the biphenyl skeleton in the thermoplastic polyimide to 30 moles or more, the content of the residues containing the biphenyl skeleton in the entire polyimide constituting the polyimide films 100 and 101 can be improved. The content ratio reduces the oxygen transmission rate and realizes the low dielectric loss tangent. On the other hand, with regard to thermoplastic polyimide, in order to ensure adhesion to the metal layer, it is necessary to increase the flexibility of the polyimide molecular chain and impart thermoplasticity. Therefore, the content of the residue containing the biphenyl skeleton is preferable. The upper limit of is 65 mol% or less.

(Acid dianhydride residue) The thermoplastic polyimide preferably contains 60 moles or more of acid dianhydride residues having a biphenyl skeleton in all acid dianhydride residues. It is more preferable to contain the biphenyltetrayl group represented by the formula (c) in the above-mentioned amount.

In addition to the residues of the acid dianhydride having a biphenyl skeleton, the thermoplastic polyimine may also contain the residues of the acid dianhydride that is generally used as a raw material for polyimine within a range that does not impair the effect of the invention. . Examples of such acid dianhydride residues include acid dianhydride residues exemplified for non-thermoplastic polyimides.

(Diamine residue) The thermoplastic polyimide preferably contains 1 mol or more of diamine residues having a biphenyl skeleton in all diamine residues, and more preferably contains 5 mol or more of diamine residues. It is more preferable to contain the biphenyldiyl group represented by the formula (b) in the above-mentioned amount. The biphenyldiyl group represented by the formula (b) has a rigid structure and has the effect of imparting an ordered structure to the entire polymer. Therefore, the dielectric loss tangent or hygroscopicity can be reduced by suppressing the movement of molecules. Furthermore, by being used as a raw material of thermoplastic polyimide, a polyimide having a low oxygen permeability and excellent long-term heat-resistant adhesiveness can be obtained.

In addition to the diamine residue having a biphenyl skeleton, the thermoplastic polyimide may also contain the residue of a diamine compound that is generally used as a raw material of the polyimide within a range that does not impair the effect of the invention. Examples of such diamine residues include residues of diamine compounds exemplified for non-thermoplastic polyimides.

In the thermoplastic polyimide, by selecting the types of the acid dianhydride residues and diamine residues, or applying two or more acid dianhydride residues or diamine residues, the respective molar ratios can be Control thermal expansion coefficient, tensile elastic modulus, glass transition temperature, etc. In addition, in the thermoplastic polyimide, when it has a plurality of polyimine structural units, it may exist in the form of a block or may exist randomly, but it is preferably present randomly.

The thermoplastic polyimide preferably contains an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic dianhydride and an aromatic diamine residue derived from an aromatic diamine. By making both the acid dianhydride residue and the diamine residue contained in the thermoplastic polyimide an aromatic group, it is possible to suppress the deterioration of the polyimide film 100, 101 in a high-temperature environment.

The concentration of the imine group of the thermoplastic polyimide is preferably 30% by weight or less. Here, the "imine group concentration" refers to _{a value obtained by dividing the molecular weight of the amide group (-(CO) 2} -N-) in the polyimide by the molecular weight of the entire structure of the polyimide. If the concentration of the imine group exceeds 30% by weight, the elastic modulus at a temperature higher than the glass transition temperature is unlikely to decrease, and the increase in polar groups also deteriorates low hygroscopicity.

The weight average molecular weight of the thermoplastic polyimide is, for example, preferably in the range of 10,000 to 400,000, and more preferably in the range of 50,000 to 350,000. If the weight average molecular weight is less than 10,000, the strength of the film will decrease and it will tend to become brittle. On the other hand, if the weight average molecular weight exceeds 400,000, the viscosity increases excessively, and defects such as uneven film thickness and streaks tend to occur during the coating operation.

In the polyimide films 100 and 101, the thermoplastic polyimide layers 120A and 120B function as adhesion layers and can improve the adhesion to metal layers such as copper foil. Therefore, the glass transition temperature of the thermoplastic polyimide is preferably within the range of 200°C or more and 350°C or less, and more preferably within the range of 200°C or more and 320°C or less.

The thermoplastic polyimide becomes, for example, an adhesive layer in contact with the wiring layer of the circuit board. Therefore, in order to suppress the diffusion of copper, it is most preferably a structure that is completely imidized. Among them, a part of polyimide may also become amide acid. The imidization rate is measured by using a Fourier transform infrared spectrophotometer (commercial product: FT/IR620 manufactured by JASCO Corporation), and using the Attenuated Total Reflection (ATR) method. The infrared absorption spectrum of the imine thin film was calculated from the absorbance derived from the C=O stretch of the iminium group at ^{1780 cm-1} based on the benzene ring absorber in the vicinity of ^{1015 cm-1.}

＜Form of polyimide film＞ The polyimide films 100 and 101 of this embodiment are not particularly limited as long as they are polyimide films that satisfy the above-mentioned conditions, and may be films (sheets) containing insulating resin, for example, laminated on copper foil, etc. Metal foil, glass plate, polyimide-based film, polyimide-based film, resin sheet such as polyester-based film, etc., are a film of insulating resin in a state on a substrate.

＜Dielectric loss tangent＞ When the polyimide films 100 and 101 are used as insulating resin layers of circuit boards, for example, in order to reduce the dielectric loss during high-frequency signal transmission, the entire film uses a separate dielectric resonator (separated dielectric resonator). (Split Post Dielectric Resonator, SPDR)) The dielectric loss tangent (Tanδ) at 10 GHz when the measurement is performed is preferably 0.004 or less. In order to improve the transmission loss of the circuit board, it is particularly important to control the dielectric loss tangent of the insulating resin layer, and to increase the effect of reducing the transmission loss by setting the dielectric loss tangent within the above range. Therefore, when the polyimide films 100 and 101 are used, for example, as an insulating resin layer of a high-frequency circuit board, the transmission loss can be efficiently reduced. If the dielectric loss tangent at 10 GHz exceeds 0.004, when the polyimide films 100 and 101 are used as the insulating resin layer of the circuit board, the loss of the electrical signal on the transmission path of the high-frequency signal is likely to increase, etc. Bad situation. The lower limit of the dielectric loss tangent at 10 GHz is not particularly limited, but it is necessary to consider the control of physical properties when the polyimide films 100 and 101 are used as the insulating resin layer of the circuit board.

＜Dielectric constant＞ When the polyimide films 100 and 101 are used as an insulating resin layer of a circuit board, for example, in order to ensure impedance matching, the dielectric constant at 10 GHz as a whole film is preferably 4.0 or less. If the dielectric constant at 10 GHz exceeds 4.0, when the polyimide films 100 and 101 are used as the insulating resin layer of the circuit board, the dielectric loss will deteriorate, and electrical signals will easily occur on the transmission path of high-frequency signals. The loss becomes larger and other undesirable conditions.

＜Filling＞ The polyimide films 100 and 101 of the present embodiment may also contain inorganic fillers or organic fillers in the non-thermoplastic polyimide layer 110 or the thermoplastic polyimide layers 120A, 120B as needed. Specifically, examples include inorganic fillers such as silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, and calcium fluoride; or fluorine-based polymer particles Or organic fillers such as liquid crystal polymer particles. These can be used 1 type or in mixture of 2 or more types. Furthermore, in the case of containing an organic filler, the organic filler does not correspond to all the monomer components constituting the non-thermoplastic polyimide layer 110 or the thermoplastic polyimide layer 120A, 120B.

[Manufacturing method of polyimide film] As a preferable aspect of the manufacturing method of the polyimide film 100, 101 of this embodiment, the following [1]-[3] can be illustrated, for example. [1] A method of repeatedly coating and drying a polyimide solution on a supporting substrate, and then performing imidization to produce polyimide films 100 and 101. [2] Repeatedly apply the polyamide acid solution on the supporting substrate and dry the operation, and then peel off the polyamide gel film from the supporting substrate, and carry out imidization to produce polyamide The method of the imine film 100, 101. [3] A method of producing polyimide films 100 and 101 by multi-layer extrusion, while coating and drying the polyimide acid solution in a state where the polyimide acid solution is laminated into multiple layers, and then performing imidization ( The following is a multilayer extrusion method).

The method of [1] may include, for example, the following steps 1a to 1c; (1a) The step of coating and drying the polyamide acid solution on the supporting substrate; (1b) A step of forming a polyimide layer by heat-treating polyamide acid on a supporting substrate and then imidizing it; and (1c) A step of obtaining polyimide films 100 and 101 by separating the supporting base material from the polyimide layer.

The method of [2] may include, for example, the following steps 2a to 2c; (2a) The step of coating and drying the polyamide acid solution on the supporting substrate; (2b) The step of separating the support substrate from the gel membrane of polyamic acid; and (2c) A step of obtaining polyimide films 100 and 101 by heat-treating and imidizing the gel film of polyimide acid.

In the method of [1] or the method of [2], by repeatedly performing step 1a or step 2a multiple times, a polyamide-acid laminated structure can be formed on the supporting substrate. In addition, the method of applying the polyamide acid solution on the support substrate is not particularly limited, and for example, it can be applied using a coating machine such as a chipped wheel, a die, a knife, or a die lip.

Regarding the method of [3], in addition to the step 1a of the method of [1] or the step 2a of the method of [2], the laminated structure of polyamide acid is simultaneously coated and applied by multi-layer extrusion. Except for drying, it can be implemented in the same manner as the method of [1] or the method of [2] described above.

It is preferable that the polyimide films 100 and 101 manufactured in this embodiment have completed the imidization of polyimide on a supporting substrate. Since the resin layer of polyimide is imidized while being fixed on the supporting substrate, the expansion and contraction of the polyimide layer during the imidization process can be suppressed, thereby maintaining the polyimide film The thickness or dimensional accuracy of 100 and 101.

[Metal Clad Laminate] The metal-clad laminate of this embodiment includes an insulating resin layer and a metal layer provided on at least one surface of the insulating resin layer, as long as part or all of the insulating resin layer is used for the polyimide film 100, 101 of the embodiment Just form it. In order to improve the adhesion between the insulating resin layer and the metal layer, the layers in the insulating resin layer that are in contact with the metal layer may be thermoplastic polyimide layers 120A and 120B.

The material of the metal layer is not particularly limited. Examples include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and these Alloys and so on. Among them, copper or copper alloys are particularly preferred. In addition, the material of the wiring layer in the circuit board mentioned later is also the same as that of a metal layer.

The thickness of the metal layer is not particularly limited. For example, when a metal foil typified by copper foil is used, it is preferably 35 μm or less, and more preferably in the range of 5 μm to 25 μm. From the viewpoint of production stability and handling properties, the lower limit of the thickness of the metal foil is preferably 5 μm. In addition, in the case of using copper foil, it may be rolled copper foil or electrolytic copper foil. In addition, as the copper foil, a commercially available copper foil can be used.

In addition, regarding the metal foil, for example, rust prevention treatment or surface treatment with, for example, siding, aluminum alkoxide, aluminum chelate, silane coupling agent, etc., may be performed in advance for the purpose of improving adhesion.

Next, with regard to the metal-clad laminate, a copper-clad laminate in which the metal layer is formed of copper foil is taken as an example, and will be described in more detail. In the copper-clad laminated board, the copper foil is provided on one side or both sides of the insulating resin layer. That is, the copper clad laminate may be a single-sided copper clad laminate (single-sided CCL (Copper Clad Laminate)) or a double-sided copper clad laminate (double-sided CCL).

The copper-clad laminated board can be prepared, for example, by preparing a resin film composed of the polyimide films 100 and 101 of the above-mentioned embodiment, sputtering metal thereon to form a seed layer, and then, for example, copper plating To form a copper foil layer. In addition, the copper-clad laminated board can also be prepared by preparing a resin film composed of the polyimide films 100 and 101 of the above-mentioned embodiment, and laminating copper foil thereon by a method such as thermocompression bonding. Furthermore, copper clad laminates can also be prepared by casting a coating solution containing polyamide acid as a precursor of polyimide on copper foil, drying to form a coating film, and then performing heat treatment And it is imidized to form a polyimide layer.

[Circuit Board] The metal-clad laminated board of the above-mentioned embodiment is mainly used effectively as a circuit board material of FPC and the like. By processing the metal layer of the metal-clad laminate into a pattern by a conventional method to form a wiring layer, the circuit board as one embodiment of the present invention can be manufactured. That is, the circuit board of this embodiment includes an insulating resin layer and a wiring layer provided on at least one surface of the insulating resin layer, as long as part or all of the insulating resin layer is used for the polyimide films 100, 101 of the embodiment. Just form it. In addition, in order to improve the adhesion between the insulating resin layer and the wiring layer, the layer in contact with the wiring layer in the insulating resin layer may be the thermoplastic polyimide layer 120A, 120B.

[Example] Examples are shown below to describe the features of the present invention in more detail. However, the scope of the present invention is not limited to the examples. In addition, in the following examples, unless otherwise specified, various measurements and evaluations are based on the following.

[Determination of Viscosity] An E-type viscometer (manufactured by Brookfield, trade name: DV-II+Pro) was used to measure the viscosity at 25°C. Set the rotation speed so that the torque becomes 10% to 90%, and read the value when the viscosity is stable 2 minutes after the start of the measurement.

[Measurement of glass transition temperature (Tg)] Regarding the glass transition temperature, a dynamic viscoelasticity measuring device (DMA: manufactured by UBM, trade name: E4000F) was used, and the heating rate was 4°C/min from 30°C to 400°C , A polyimide film with a size of 5 mm×20 mm was measured at a frequency of 11 Hz, and the temperature at which the change in elastic modulus (tanδ) was the largest was set as the glass transition temperature. Furthermore, it will be shown that the memory elastic modulus at 30°C measured by DMA is 1.0×10 ⁹ Pa or more and the glass transition temperature + 30°C or less in the temperature range is less than 1.0×10 ⁸ The case of Pa is set as "thermoplastic", and it will show that the memory elastic modulus at 30°C is 1.0×10 ⁹ Pa or more and the memory elastic modulus in the temperature range of glass transition temperature + 30°C is 1.0×10 ⁸ The case of Pa or more is referred to as "non-thermoplastic".

[Determination of Coefficient of Thermal Expansion (CTE)] Using a thermomechanical analyzer (manufactured by Bruker, trade name: 4000SA), a load of 5.0 g is applied to a polyimide film with a size of 3 mm×20 mm, and the temperature is raised from 30°C to a temperature at a constant heating rate. It was kept at the temperature for 10 minutes until 265°C, and then cooled at a rate of 5°C/min to obtain the average thermal expansion coefficient (thermal expansion coefficient) from 250°C to 100°C.

[Determination of moisture absorption rate] Two test pieces of polyimide film (width: 4 cm×length: 25 cm) were prepared, and dried at 80°C for 1 hour. Immediately after drying, put it into a 23°C/50%RH constant temperature and humidity room and let it stand for more than 24 hours. The weight change before and after that is calculated by the following formula. Moisture absorption rate (weight%)=[(weight after moisture absorption-weight after drying)/weight after drying]×100

[Measurement of dielectric constant and dielectric loss tangent] A vector network analyzer (manufactured by Agilent (Agilent), trade name: E8363C) and a separate dielectric resonator (SPDR resonator) were used to measure the dielectric constant and dielectric constant of the polyimide film at a frequency of 10 GHz Loss tangent. In addition, the material used in the measurement is a material left for 24 hours under the conditions of temperature: 24°C to 26°C and humidity: 45% to 55%.

[Calculation of the Concentration of _{Amide Groups] The value obtained by dividing the molecular weight of the imine group (-(CO) 2} -N-) by the molecular weight of the entire structure of the polyimide group is defined as the concentration of the imine group.

[Measurement of surface roughness of copper foil] Regarding the surface roughness of the copper foil, an atomic force microscope (Atomic Force Microscope, AFM) (manufactured by Bruker AXS (Bruker AXS), trade name: Dimension Icon) scanning probe microscope (Scanning Probe Microscopy, SPM)), probes (manufactured by Bruker AXS, trade name: TESPA (NCHV), tip curvature radius 10 nm, spring constant 42 N/m), using tapping mode, in copper foil Measure the surface in the range of 80 μm×80 μm, and obtain the ten-point average roughness (Rzjis).

[Measurement of oxygen transmission rate] Under the conditions of a temperature of 23°C±2°C and a humidity of 65%RH±5%RH, the oxygen transmission rate was measured according to the differential pressure method of Japanese Industrial Standards (JIS) K7126-1. In addition, as the vapor transmission rate measuring device, GTR-30XAD2 manufactured by GTR Technology (TECH) and G2700T･F manufactured by Yanako Technical Science (Yanako Technical Science) were used.

[Measurement of initial peel strength] The copper foil of the copper-clad laminate (copper foil/multi-layer polyimide layer) is processed with a width of 1 mm in the resin coating direction at 10 mm intervals, and then cut into width: 8 cm × length: 4 cm. The peel strength is measured by using a Tensilon Tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., trade name: Strograph VE-1D), and using a double-sided tape to cut the resulting sample of polyamide The amine layer was fixed on the aluminum plate, and the circuit-processed copper foil was peeled in a 180° direction at a speed of 50 mm/min. The median strength at 10 mm peeling from the polyimide layer was determined and set as the initial peel strength.

[Measurement of peel strength after heating] The copper foil of the copper-clad laminate (copper foil/multi-layer polyimide layer) is processed with a width of 1 mm in the resin coating direction at 10 mm intervals, and then cut into width: 8 cm × length: 4 cm. The sample obtained by cutting was stored in a hot-air oven (in an atmospheric environment) set at 150°C, and taken out after 1000 hours. The peel strength was measured by using a Tensilon Tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., trade name: Strograph VE-1D), using double-sided tape to remove the polyimide of the measurement sample The layer was fixed on an aluminum plate, and the circuit-processed copper foil was peeled at a speed of 50 mm/min in the 180° direction, and the median strength when the polyimide layer was peeled off by 10 mm was obtained.

[Measurement of thickness of polyimide layer] For the copper clad laminate, the copper foil was etched and removed using an aqueous ferric chloride solution to obtain a polyimide film. The obtained polyimide film was cut into short strips, resin-embedded, and then cut in the thickness direction of the film using a microtome to produce ultrathin sections of about 100 nm. For the ultra-thin sections produced, the STEM function of the Scanning Electron Microscope (SEM) (SU9000) manufactured by Hitachi High-technologies was used to observe at an accelerating voltage of 30 kV, and to measure each The thickness of the polyimide layer was 5 points each, and the average value was taken as the thickness of each polyimide layer.

The abbreviations used in the examples and reference examples indicate the following compounds. PMDA: Pyromellitic dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TPE-R: 1,3-bis(4-aminophenoxy)benzene TPE-Q: 1,4-bis(4-aminophenoxy)benzene DAPE: 4,4'-diamino-diphenyl ether PDA: p-phenylenediamine BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane Dianiline-P: 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene (manufactured by Mitsui Chemicals Co., Ltd., trade name: Dianiline-P) DDA: aliphatic diamine with 36 carbon atoms (manufactured by Croda Japan, trade name: PRIAMINE 1074, amine value: 210 mgKOH/g, dimerization of cyclic structure and chain structure The content of the diamine mixture and dimer component: 95% by weight or more) DMAc: N,N-Dimethylacetamide

(Synthesis example 1) Under nitrogen flow, 12.061 g of m-TB (0.0568 mol), 0.923 g of TPE-Q (0.0032 mol) and 1.0874 g of dianiline-P (0.0032 mol) were put into a 300 ml separable flask ) And DMAc in an amount such that the solid content concentration after polymerization becomes 15% by weight, and is stirred and dissolved at room temperature. Next, after adding 6.781 g of PMDA (0.0311 mol) and 9.147 g of BPDA (0.0311 mol), stirring was continued at room temperature for 3 hours and the polymerization reaction was performed to obtain a polyamide acid solution a. The solution viscosity of polyamide acid solution a is 29,800 cps.

Next, the copper foil 1 (electrolytic copper foil, thickness: 12 μm, surface roughness Rzjis: 2.1 μm on the resin side) is uniformly coated with polyamide acid solution a so that the thickness after curing becomes about 25 μm, Then, heat and dry at 120°C to remove the solvent. Furthermore, stepwise heat treatment is performed from 120°C to 360°C within 30 minutes to complete the imidization. With respect to the obtained copper-clad laminated board, the copper foil was etched and removed using an aqueous ferric chloride solution to prepare a polyimide film a (non-thermoplastic, Tg: 316° C., moisture absorption rate: 0.61% by weight). In addition, the polyimide group concentration of the polyimide film a is 31.6% by weight.

(Synthesis example 2) Under nitrogen flow, put 11.825 g of m-TB (0.0557 mol), 0.905 g of TPE-Q (0.0031 mol) and 1.653 g of DDA (0.0031 mol) into a 300 ml separable flask, and polymerization The subsequent solid content concentration became 15% by weight of DMAc, which was stirred and dissolved at room temperature. Next, after adding 6.649 g of PMDA (0.0305 mol) and 8.968 g of BPDA (0.0305 mol), stirring was continued for 3 hours at room temperature and the polymerization reaction was performed to obtain a polyamide acid solution b. The solution viscosity of the polyamide acid solution b is 27,800 cps.

Next, the polyamide acid solution b is uniformly coated on the copper foil 1 so that the thickness after curing becomes approximately 25 μm, and then heated and dried at 120° C. to remove the solvent. Furthermore, stepwise heat treatment is performed from 120°C to 360°C within 30 minutes to complete the imidization. With respect to the obtained copper-clad laminated board, the copper foil was etched and removed using an aqueous ferric chloride solution to prepare a polyimide film b (non-thermoplastic, Tg: 258° C., moisture absorption rate: 0.54% by weight). In addition, the polyimine group concentration of the polyimide film b was 30.9% by weight.

(Synthesis example 3) Under nitrogen flow, put 11.920 g of m-TB (0.0562 mol) and 2.897 g of TPE-Q (0.0099 mol) into a 300 ml separable flask, and the solid content concentration after polymerization became 15% by weight The amount of DMAc is stirred and dissolved at room temperature. Next, after adding 11.354 g of PMDA (0.0521 mol) and 3.829 g of BPDA (0.0130 mol), stirring was continued for 3 hours at room temperature and polymerization reaction was performed to obtain a polyamide acid solution c. The solution viscosity of polyamide acid solution c is 31,200 cps.

Next, the polyamide acid solution c was uniformly coated on the copper foil 1 so that the thickness after hardening became about 25 μm, and then heated and dried at 120° C. to remove the solvent. Furthermore, stepwise heat treatment is performed from 120°C to 360°C within 30 minutes to complete the imidization. With respect to the obtained copper-clad laminated board, the copper foil was etched and removed using an aqueous ferric chloride solution to prepare a polyimide film c (non-thermoplastic, Tg: 375° C., moisture absorption rate: 0.81% by weight). In addition, the polyimide group concentration of the polyimide film c was 33.2% by weight.

(Synthesis example 4) Under a nitrogen stream, 1.548 g of PDA (0.0143 mol) and 11.465 g of DAPE (0.0573 mol) and DMAc are put into a 300 ml separable flask, and the solid content concentration after polymerization becomes 15% by weight. Stir and dissolve at room temperature. Next, after adding 10.764 g of PMDA (0.0494 mol) and 6.223 g of BPDA (0.0212 mol), stirring was continued for 3 hours at room temperature and polymerization reaction was performed to obtain a polyamide acid solution d. The solution viscosity of the polyamide acid solution d is 23,500 cps.

Next, the polyamide acid solution d is cast from the slit of the T-die mold so that the thickness after hardening becomes 25 μm, and is extruded on a smooth band-shaped metal support in a drying furnace to form a thin film. After heating at 130°C for a predetermined period of time, it was peeled off from the support to obtain a self-supporting film. Furthermore, both ends in the width direction of the self-supporting film are held and inserted into a continuous heating furnace, and the film is heated and imidized under the conditions from 100° C. to a maximum heating temperature of 380° C. , Thereby preparing a polyimide film d (non-thermoplastic, Tg: >400°C, moisture absorption rate: 1.14% by weight). In addition, the polyimine group concentration of the polyimine constituting the polyimide film d was 36.2% by weight.

(Synthesis example 5) Under a nitrogen stream, 15.591 g of BAPP (0.0380 mol) and DMAc in an amount such that the solid content concentration after polymerization becomes 12% by weight were put into a 300 ml separable flask, and the mixture was stirred and dissolved at room temperature. Next, after adding 8.409 g of PMDA (0.0386 mol), stirring was continued for 3 hours at room temperature and the polymerization reaction was performed to obtain a polyamide acid solution e. The solution viscosity of polyamide acid solution e is 2,350 cps.

Next, the polyamide acid solution e was uniformly coated on the copper foil 1 so that the thickness after hardening became about 10 μm, and then heated and dried at 120° C. to remove the solvent. Furthermore, stepwise heat treatment is performed from 120°C to 360°C within 30 minutes to complete the imidization. With respect to the obtained copper-clad laminated board, the copper foil was etched and removed using a ferric chloride aqueous solution, thereby preparing a polyimide film e (thermoplasticity, Tg: 320° C., moisture absorption rate: 0.55% by weight). In addition, the polyimine group concentration of the polyimide film e constituting the polyimide film e was 23.6% by weight.

(Synthesis example 6) Under nitrogen flow, put 1.847 g of m-TB (0.0087 mol) and 10.172 g of TPE-R (0.0348 mol) into a 300 ml separable flask, and the solid content concentration after polymerization became 12% by weight The amount of DMAc is stirred and dissolved at room temperature. Next, after adding 2.889 g of PMDA (0.0132 mol) and 9.092 g of BPDA (0.0309 mol), stirring was continued for 3 hours at room temperature and polymerization reaction was performed to obtain a polyamide acid solution f. The solution viscosity of the polyamide acid solution f is 2,210 cps.

Next, the polyamide acid solution f was uniformly coated on the copper foil 1 so that the thickness after hardening became about 10 μm, and then heated and dried at 120° C. to remove the solvent. Furthermore, stepwise heat treatment is performed from 120°C to 360°C within 30 minutes to complete the imidization. With respect to the obtained copper-clad laminated board, the copper foil was etched and removed using an aqueous ferric chloride solution to prepare a polyimide film f (thermoplasticity, Tg: 226° C., moisture absorption rate: 0.41% by weight). In addition, the polyimine group concentration of the polyimine constituting the polyimide film f was 27.4% by weight.

[Example 1] Coat polyamide acid solution f uniformly on copper foil 2 (electrolytic copper foil, thickness: 12 μm, resin side surface roughness Rzjis: 0.6 μm) so that the thickness after hardening becomes 2.5 μm, and then apply it to 120 Heat and dry at ℃ for 1 minute to remove the solvent. The resultant was uniformly coated with the polyamide acid solution a so that the thickness after curing became 25 μm, and then heated and dried at 120° C. for 3 minutes to remove the solvent. Furthermore, polyamide f was uniformly coated on the resultant so that the thickness after hardening became 2.5 μm, and then heated and dried at 120° C. for 1 minute to remove the solvent. After that, stepwise heat treatment is performed from 140° C. to 360° C. to complete the imidization, and the copper-clad laminate 1 is prepared. The obtained copper-clad laminate 1 was used to measure the initial peel strength and the peel strength after heating, and the results were 1.06 kN/m and 0.69 kN/m, respectively. Table 1 shows the results of each measurement.

With respect to the copper-clad laminated board 1, the copper foil was etched and removed using an aqueous ferric chloride solution to obtain a polyimide film 1a. For the obtained polyimide film 1a, the CTE, dielectric properties, and oxygen transmission rate were evaluated. The results were CTE: 22 ppm/K, dielectric constant: 3.56, dielectric loss tangent: 0.0032, and oxygen transmission rate: 4.59×10 ^-14 mol/(m ² ･s･Pa). Table 2 shows the results of each measurement.

[Example 2 to Example 4, Comparative Example 1, and Reference Example 1 to Reference Example 2] Except that the polyamide acid solution described in Table 1 was used and the thickness structure was changed, the copper-clad laminates of Examples 2 to 4, Comparative Example 1, and Reference Example 1 to Reference Example 2 were obtained in the same manner as in Example 1. 2 ~ Copper clad laminate 4, copper clad laminate 5 and copper clad laminate 6 ~ copper clad laminate 7 and polyimide film 2a ~ polyimide film 4a, polyimide film 5a and polyimide Amine film 6a to polyimide film 7a. Each measurement result is shown in Table 1 and Table 2.

[Table 1] Copper Clad Laminate species Structure of insulating resin layer Peel strength [kN/m] Layer i Types of polyamic acid solution Properties of polyimide Thickness [μm] Early After heating Example 1 1 level one f Thermoplastic 2.5 1.06 0.69 Second floor a Non-thermoplastic 25 the third floor f Thermoplastic 2.5 2 2 level one f Thermoplastic 2.5 1.07 0.79 Second floor a Non-thermoplastic 30 the third floor f Thermoplastic 2.5 3 3 level one f Thermoplastic 2.5 1.11 0.89 Second floor a Non-thermoplastic 45 the third floor f Thermoplastic 2.5 4 4 level one e Thermoplastic 2.5 1.19 0.63 Second floor a Non-thermoplastic 30 the third floor e Thermoplastic 2.5 Comparative example 1 5 level one e Thermoplastic 2.5 1.29 0.39 Second floor c Non-thermoplastic 30 the third floor e Thermoplastic 2.5 Reference example 1 6 level one f Thermoplastic 2.5 0.99 0.35 Second floor b Non-thermoplastic 30 the third floor f Thermoplastic 2.5 2 7 level one f Thermoplastic 2.5 1.14 0.28 Second floor a Non-thermoplastic 10 the third floor f Thermoplastic 2.5

[Table 2] Polyimide film species Layer i Proportion of monomer residues with biphenyl skeleton [mol%] CTE [ppm/K] Oxygen transmission rate [mol/(m ² ･s･Pa)] Dielectric characteristics (10 GHz) Dielectric constant Dielectric loss tangent Example 1 1a level one 45 65.8 twenty two 4.59×10 ^-14 3.56 0.0032 Second floor 70 the third floor 45 2 2a level one 45 66.4 twenty two 3.91×10 ^-14 3.56 0.0032 Second floor 70 the third floor 45 3 3a level one 45 67.5 twenty one 2.71×10 ^-14 3.56 0.0032 Second floor 70 the third floor 45 4 4a level one 0 60.0 twenty two 4.39×10 ^-14 3.56 0.0036 Second floor 70 the third floor 0 Comparative example 1 5a level one 0 45.4 twenty two 7.73×10 ^-14 3.44 0.0053 Second floor 53 the third floor 0 Reference example 1 6a level one 45 66.4 twenty two 7.18×10 ^-14 3.53 0.0027 Second floor 70 the third floor 45 2 7a level one 45 61.7 twenty four 9.59×10 ^-14 3.56 0.0031 Second floor 70 the third floor 45

Comparative example 2 The polyamide acid solution d was cast from the slit of the T-die mold so that the thickness after hardening became 30 μm, and was extruded on a smooth band-shaped metal support in a drying furnace to form a thin film. After heating at °C for a predetermined period of time, it was peeled off from the support to obtain a self-supporting film. Furthermore, while continuously conveying the self-supporting film, while using a die coater to coat the polyamide acid solution e on the air surface of the self-supporting film so that the thickness after curing becomes 2.5 μm, the solution e was heated at 120°C. Dry in a drying oven for a specified time. Next, the polyamide solution e was applied to the surface opposite to the surface on which the polyamide acid solution e was applied, in the same manner as described above, so that the thickness after curing became 2.5 μm, and dried at 120°C. Dry in the oven for a specified time. Both ends in the width direction of the self-supporting film are held and inserted into a continuous heating furnace, and the film is heated and imidized under the conditions of from 100°C to a maximum heating temperature of 380°C. A polyimide film 8b is obtained. A copper foil was laminated on one side of the polyimide film 8b, and a Teflon (registered trademark) film was laminated on the other side, and thermocompression-bonded for 15 minutes at a temperature of 320°C and a pressure of 340 MPa. After crimping, the Teflon (registered trademark) film is peeled off, thereby preparing a copper clad laminate 8. The obtained copper-clad laminate 8 was used to measure the initial peel strength and the peel strength after heating, and the results were 1.15 kN/m and 1.01 kN/m, respectively.

With respect to the copper-clad laminated board 8, the copper foil was etched and removed in the same manner as in Example 1 to obtain a polyimide film 8a. For the obtained polyimide film 8a, the CTE, dielectric properties, and oxygen transmission rate were evaluated. The results were CTE: 22 ppm/K, dielectric constant: 3.65, dielectric loss tangent: 0.0073, and oxygen transmission rate: 1.17×10 ^-14 mol/(m ² ･s･Pa).

As mentioned above, the embodiment of the present invention has been described in detail for the purpose of illustration, but the present invention is not restricted by the embodiment and can be variously modified.

100, 101: Polyimide film 110: Non-thermoplastic polyimide layer 120A, 120B: Thermoplastic polyimide layer T1, T2A, T2B, T3: thickness

Fig. 1 is a schematic cross-sectional view showing the structure of a polyimide film according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing another example of the structure of the polyimide film according to the embodiment of the present invention.

100: Polyimide film

110: Non-thermoplastic polyimide layer

120A: Thermoplastic polyimide layer

T1, T2A, T3: thickness

Claims (6)

A polyimide film has a non-thermoplastic polyimide layer and a thermoplastic polyimide layer, the non-thermoplastic polyimide layer comprises a non-thermoplastic polyimide, and the thermoplastic polyimide layer is laminated on At least one side of the non-thermoplastic polyimide layer contains thermoplastic polyimide; and the polyimide film is characterized in that it satisfies the following conditions (i) to (iii); (i) thermal expansion coefficient Within the range of 10 ppm/K～30 ppm/K; (ii) The oxygen transmission rate is 5.5×10 ^-14 mol/(m ² ･s･Pa) or less; (iii) Compared with the non-thermoplastic poly The ratio of all monomer residues derived from all monomer components of imines and the thermoplastic polyimines, calculated by the following formula (1), of monomer residues having a biphenyl skeleton is 50 mol% or more ；

...(1) [In the formula (1), M _i is all monomer residues derived from all monomer components in the polyimide layer constituting the i-th layer, and has biphenyl the proportion of monomer residues occupied skeleton (unit: mol%), L _i is the i-th layer thickness of polyimide layer (unit: μm), L is the thickness of the polyimide film (unit: μm ), n is an integer greater than 2]. The polyimide film according to claim 1, wherein in addition to satisfying the conditions (i) to (iii), the following condition (iv) is further satisfied; (Iv) Among all monomer residues derived from all monomer components in the thermoplastic polyimide, the ratio of monomer residues having a biphenyl skeleton is 30 mol% or more. The polyimide film according to claim 1 or claim 2, wherein the overall thickness is in the range of 30 μm to 60 μm. The polyimide film according to claim 3, wherein the ratio T2/T1 of the total thickness T2 of the thermoplastic polyimide layer to the overall thickness T1 of the polyimide film is 0.17 or less. A metal-clad laminated board includes an insulating resin layer and a metal layer provided on at least one surface of the insulating resin layer, and the metal-clad laminated board is characterized in that: The insulating resin layer has a thermoplastic polyimide layer in contact with the surface of the metal layer and an indirectly laminated non-thermoplastic polyimide layer, and includes the polyimide film according to claim 1. A circuit substrate includes an insulating resin layer and a wiring layer provided on at least one surface of the insulating resin layer, and the circuit substrate is characterized in that: The insulating resin layer has a thermoplastic polyimide layer in contact with the wiring layer and an indirectly laminated non-thermoplastic polyimide layer, and includes the polyimide film according to claim 1.

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