TWI869502B - Low dielectric stack - Google Patents

Abstract

The subject of the present invention is to provide a laminate with good adhesion, dielectric properties and linear expansion. The solution of the present invention is a laminate, which is laminated in order of a metal substrate, an adhesive layer and a resin substrate, wherein the adhesive layer contains a filler (A), an acid-modified polyolefin (B) and a cured epoxy resin (C); in a cross section of the adhesive layer in a direction perpendicular to the surface of the laminate, the number a1 of the filler (A) contained in the region from the midpoint to the side close to the surface of the metal substrate is greater than the number b1 of the filler (A) contained in the region from the midpoint to the side close to the surface of the resin substrate.

Description

Low dielectric stack

The present invention relates to a laminate having low dielectric properties. More specifically, the present invention relates to a laminate that can be used in a flexible printed circuit board, a cover film, or an adhesive sheet.

Flexible printed circuit boards (FPCs) are often used to assemble electronic circuit boards into small and complex interiors because they have excellent flexibility and can cope with the multifunctionality and miniaturization of computers and mobile phones. In recent years, electronic equipment has been miniaturized, lightweight, high-density, and high-output. With these trends, the performance requirements for wiring boards (electronic circuit boards) have gradually increased. In particular, with the progress of high-speed transmission signals and high-frequency signals in FPCs, the requirements for low dielectric properties (low dielectric constant, low loss tangent) in the high-frequency region of FPCs have increased. Patent document 1 discloses a surface coating film (laminated body) having a thermosetting adhesive layer, which is formed from a thermosetting adhesive composition containing a polyolefin resin, a carbodiimide resin, a multifunctional epoxy resin and a filler. [Prior art document] [Patent document]

[Patent Document 1] Japanese Patent Application Publication No. 2019-127501

[The problem that the invention wants to solve]

However, although the coating film (laminated body) described in Patent Document 1 contains fillers, the linear expansion of the laminate is insufficient because the dispersion of the fillers in the adhesive layer is not taken into consideration. The present invention focuses on the above-mentioned problems and aims to provide a laminate having excellent adhesive properties, dielectric properties and linear expansion of the adhesive layer. [Means for Solving the Problem]

A laminated body is a metal substrate, an adhesive layer, and a resin substrate laminated in order, wherein the adhesive layer contains a filler (A), an acid-modified polyolefin (B), and a cured epoxy resin (C); In a cross section of the adhesive layer in a direction perpendicular to the surface of the laminated body, the number a1 of the filler (A) contained in the region from the midpoint to the side close to the surface of the metal substrate is greater than the number b1 of the filler (A) contained in the region from the midpoint to the side close to the surface of the resin substrate.

The ratio of a1 to b1 is preferably a1/b1=less than 100/greater than 0~greater than 50/less than 50.

The filler (A) is preferably selected from the group consisting of phosphorus-containing flame retardant fillers, aluminum hydroxide, silicon oxide, titanium oxide and carbon black. The curing component of the adhesive layer preferably contains oligophenylene ether (D) and/or polycarbodiimide (E) with a numerical average molecular weight of less than 3000.

The adhesive layer preferably has a relative capacitance (εc) of 3.0 or less and a loss tangent (tanδ) of 0.02 or less at 1 GHz.

A printed circuit board comprising the above-mentioned laminate as a constituent element. [Effect of the invention]

The laminate of the present invention has excellent adhesion and dielectric properties and linear expansion properties due to the proper setting of the dispersion of the filler in the adhesive layer, and can provide a laminate with good dimensional stability.

The present invention is specifically described below based on the following implementation forms. The present invention is not limited to the following implementation forms and can be implemented by applying appropriate changes within the scope of the above and following purposes, all of which are included in the technical scope of the present invention.

<Laminated body> The laminated body of the present invention is laminated in the order of metal substrate, adhesive layer and resin substrate. The metal substrate and adhesive layer can be laminated directly, or another substrate (layer) can be laminated between the two. It is preferred to laminate the metal substrate and adhesive layer directly. In addition, the adhesive layer and resin substrate can be laminated directly, or another substrate (layer) can be laminated between the two. It is preferred to laminate the adhesive layer and resin substrate directly. That is, it is best to directly stack the metal substrate, adhesive layer and resin substrate (three layers of metal substrate/adhesive layer/resin substrate).

In addition, the laminated body can further be a laminated body of different substrates with adhesive layers interposed therebetween. For example, there can be four layers of adhesive layer/metal substrate/adhesive layer/resin substrate, four layers of metal substrate/adhesive layer/resin substrate/adhesive layer, five layers of adhesive layer/metal substrate/adhesive layer/resin substrate/adhesive layer, etc.

An example of a laminate is shown in FIG1 . The laminate 10 of FIG1 is a laminate of a metal substrate 1, an adhesive layer 3, and a resin substrate 2, etc. The adhesive layer 3 includes a region 3a close to the surface side of the metal substrate (hereinafter also referred to as the adhesive layer 3a) and a region 3b close to the surface side of the resin substrate (hereinafter also referred to as the adhesive layer 3b).

The preparation of the laminate is not particularly limited, and can be carried out, for example, by the following method. First, an adhesive composition a containing filler (A), acid-modified polyolefin (B) and epoxy resin (C) is applied to the surface of a metal substrate 1, and an adhesive layer 3a is prepared after drying. Then, an adhesive composition b containing a filler (A) content less than that of the adhesive composition a is applied to the surface, and an adhesive layer 3b is prepared after drying. Then, a resin substrate 2 is laminated, and a laminate can be obtained after heat treatment (hardening). Or conversely, the adhesive composition b can be applied on the surface of the resin substrate 2, dried to form the adhesive layer 3b, and then the adhesive composition a can be applied and dried to form the adhesive layer 3a, and then the metal substrate 1 can be laminated and heat treated (hardened) to obtain a laminate.

When using a laminate as a component of a printed circuit board, it is preferred to form a conductive circuit first.

<Adhesive layer> The adhesive layer of the present invention is a hardened material containing filler (A), acid-modified polyolefin (B) and epoxy resin (C), and the number a1 of the filler (A) in the adhesive layer 3a is greater than the number b1 of the filler (A) in the adhesive layer 3b.

The ratio of the number a1 of the adhesive layer 3a to the number b1 of the adhesive layer 3b (a1/b1) is preferably less than 100/greater than 0 to greater than 50/less than 50. In terms of achieving good linear expansion, 99/1 to 51/49 is preferred, 98/2 to 52/48 is more preferred, 97/3 to 53/47 is more preferred, 96/4 to 54/46 is more preferred, and 95/5 to 55/45 is the best.

The area of the adhesive layer 3a and the adhesive layer 3b in the adhesive layer is measured from the midpoint of the length (thickness of the adhesive layer 3) in the direction perpendicular to the surface of the laminate, with the side close to the metal substrate 1 being the adhesive layer 3a and the side close to the resin substrate 2 being 3b. The midpoint here means the midpoint between the surface of the adhesive layer contacting the metal substrate 1 and the surface contacting the resin substrate 2, and when the thickness of the adhesive layer is 100%, the position is 50% from the metal substrate 1 and the position is also 50% from the resin substrate 2. That is, the area of the adhesive layer 3a is within 50% of the metal substrate 1 of the adhesive layer 3. In addition, the area of the adhesive layer 3b is within 50% of the resin substrate 2 of the adhesive layer 3. In addition, the adhesive layer 3a and the adhesive layer 3b may have a clear boundary surface, or may be integrated without a clear boundary surface.

The film thickness (thickness) of the adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, more preferably 15 μm or more, and particularly preferably 20 μm or more in order to achieve good bonding strength. In addition, in order to impart flexibility to the adhesive layer, it is preferably 200 μm or less, more preferably 150 μm or less, more preferably 100 μm or less, and particularly preferably 50 μm.

The number of fillers (A) can be measured using an electron microscope. Specifically, the laminate is cut in a direction perpendicular to the surface, and the number of fillers (A) contained in the adhesive layer 3a and the adhesive layer 3b in the cross section is visually counted. The number of fillers (A) contained in the adhesive layer is proportional to the content of fillers (A) contained in the adhesive composition coated on the resin substrate or the metal substrate. In addition, fillers (A) with a length less than 15nm have a weak influence on linear expansion and are not included in the calculation.

<Filler (A)> The filler (A) used in the present invention (hereinafter also referred to as component (A)) is not particularly limited if it can exert the effect of low linear expansion when the dispersion in the adhesive layer is appropriately set. Preferably, at least one of the group consisting of phosphorus-containing flame retardant fillers, aluminum hydroxide, silicon oxide, titanium oxide and carbon black is selected.

As the phosphorus-containing flame retardant filler, there is no particular limitation as long as the filler contains phosphorus atoms in its structure. Examples thereof include phosphinic acid derivatives or phosphazene compounds, with phosphinic acid derivatives being preferred, and phenanthrene-type phosphinic acid derivatives being more preferred. Examples of the phenanthrene-type phosphinic acid derivatives include 9,10-dihydro-9-oxo-10-phosphophananthrene-10-oxide (Sanko Co., Ltd., trade name: HCA), 10-benzyl-10-hydro-9-oxo-10-phosphophananthrene-10-oxide (Sanko Co., Ltd., trade name: BCA), 10-(2,5-dihydroxyphenyl)-10-H-9-oxo-10-phosphophananthrene-10-oxide (Sanko Co., Ltd., trade name: HCA-HQ), and a finely pulverized product of 10-(2,5-dihydroxyphenyl)-10-H-9-oxo-10-phosphophananthrene-10-oxide (Sanko Co., Ltd., trade name: HCA-HQ-HS). These may be used alone or in combination of two or more. Among them, HCA-HQ-HS is the best.

Examples of commercially available aluminum hydroxide include HYGILITE (registered trademark) H42M, HYGILITE H43M, HYGILITE H42STV manufactured by Showa Denko Co., Ltd., and B1403 and B1403T manufactured by Nippon Light Metal Co., Ltd. These can be used alone or in combination of two or more. Among them, HYGILITE H42M manufactured by Showa Denko Co., Ltd. is preferred.

Examples of commercially available silicon oxide include SO-C1, SO-C2, SO-C3, SO-C4, SO-C5, SO-C6 manufactured by Admatechs, and FB-3SDC manufactured by Denka. These can be used alone or in combination of two or more. Among them, FB-3SDC manufactured by Denka is preferred.

Examples of commercially available titanium oxide include TIPAQUE (registered trademark) CR-60 manufactured by Ishihara Industry Co., Ltd. and JR-403 manufactured by TAYCA Co., Ltd. These can be used alone or in combination of two or more. Among them, JR-403 manufactured by TAYCA Co., Ltd. is preferred.

Examples of commercially available carbon black include the good-flowability #MA100 and the general-purpose #44 manufactured by Mitsubishi Chemical Co., Ltd. These can be used alone or in combination of two or more. Among them, the good-flowability #MA100 is preferred.

The content of the filler (A) is preferably 0.1 parts by mass or more based on 100 parts by mass of the acid-modified polyolefin (B). In order to improve the linear expansion property, it is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more. In addition, in order to improve the adhesion, it is preferably 50 parts by mass or less, preferably 40 parts by mass or less, and more preferably 30 parts by mass or less.

The shape of the filler (A) is not particularly limited, and at least one of the fillers selected from the group consisting of spherical fillers, needle-shaped fillers, rod-shaped fillers, fiber-shaped fillers, flat fillers, flaky fillers, and plate-shaped fillers is preferred. Among them, if a spherical filler is used, the unevenness of stress concentration can be reduced, and the strain during thermal expansion can be easily reduced. In addition, if a filler selected from the group consisting of spherical fillers, needle-shaped fillers, rod-shaped fillers, fiber-shaped fillers, flat fillers, flaky fillers, and plate-shaped fillers can be used alone or in combination.

The filler (A) preferably has a major diameter of 15 nm or more. By setting the major diameter to be 15 nm or more, it is easy to improve the linear expansion. Therefore, the major diameter of the filler (A) is preferably 20 nm or more, more preferably 50 nm or more, and particularly preferably 0.1 μm or more. On the other hand, the upper limit of the major diameter of the filler (A) is not particularly limited, and may be, for example, 50 μm or less, 30 μm or less, 10 μm or less, 5 μm or less, or 3 μm or less.

[Acid-modified polyolefin (B)] The acid-modified polyolefin (B) used in the present invention (hereinafter also referred to as component (B)) is not particularly limited, and is preferably obtained by grafting at least one of α,β-unsaturated carboxylic acid and its anhydride onto a polyolefin resin. Polyolefin resin means a polymer having a hydrocarbon skeleton as the main component, such as a homopolymerization of olefin monomers such as ethylene, propylene, butene, butadiene, isoprene, or a copolymerization with other monomers, and the hydrogenate and halogenide of the obtained polymer. That is, the acid-modified polyolefin is preferably obtained by grafting at least one of α,β-unsaturated carboxylic acid and its anhydride onto at least one of polyethylene, polypropylene and propylene-α-olefin copolymer.

The propylene-α-olefin copolymer is obtained by copolymerizing propylene as the main component with an α-olefin. Examples of the α-olefin include ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate, etc., and one or more of them can be used. Among these α-olefins, ethylene and 1-butene are preferred. The ratio of the propylene component to the α-olefin component of the propylene-α-olefin copolymer is not particularly limited, and preferably the propylene component is 50 mol% or more, and more preferably 70 mol% or more.

At least one of α,β-unsaturated carboxylic acid and its anhydride, for example, maleic acid, itaconic acid, liraconic acid and their anhydrides. Among them, anhydrides are preferred, and maleic anhydride is more preferred. Specifically, maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, maleic anhydride-modified propylene-butene copolymer, maleic anhydride-modified propylene-ethylene-butene copolymer, etc. can be exemplified. Such acid-modified polyolefins can be used alone or in combination of two or more.

From the viewpoint of heat resistance and adhesion to resin substrates and metal substrates, the acid value of the acid-modified polyolefin (B) is preferably 5 mgKOH/g or more, more preferably 6 mgKOH/g or more, and more preferably 7 mgKOH/g or more. By making the acid value of the acid-modified polyolefin (B) above the above lower limit, the compatibility with the epoxy resin (C) can be improved, and excellent bonding strength can be exhibited. In addition, the crosslinking density becomes higher and the solder heat resistance becomes good. The upper limit is preferably 40 mgKOH/g or less, preferably 30 mgKOH/g or less, and more preferably 20 mgKOH/g or less. By making the acid value of the acid-modified polyolefin (B) below the above upper limit, the adhesion becomes good.

The number average molecular weight (Mn) of the acid-modified polyolefin (B) is preferably in the range of 10,000 to 50,000. It is more preferably in the range of 15,000 to 45,000, more preferably in the range of 20,000 to 40,000, and particularly preferably in the range of 22,000 to 38,000. By making the number average molecular weight (Mn) of the acid-modified polyolefin (B) above the lower limit, the cohesion can be improved and excellent adhesion can be exhibited. In addition, when it is below the upper limit, the fluidity is excellent and the workability is good.

The acid-modified polyolefin (B) is preferably a crystalline acid-modified polyolefin. The crystalline property in the present invention means that the temperature is increased from -100°C to 250°C at 20°C/min using a differential scanning calorimeter (DSC), and a clear melting peak is shown in the temperature increase process.

The melting point (Tm) of the acid-modified polyolefin (B) is preferably in the range of 50°C to 120°C. It is more preferably in the range of 60°C to 100°C, and most preferably in the range of 70°C to 90°C. By making the melting point (Tm) of the acid-modified polyolefin (B) above the lower limit, the cohesive force derived from the crystallization becomes good, and excellent adhesion and solder heat resistance can be exhibited. In addition, by making the melting point (Tm) of the acid-modified polyolefin (B) below the upper limit, the solution stability and fluidity are excellent, and the workability during bonding becomes good.

The fusion heat (ΔH) of the acid-modified polyolefin (B) is preferably in the range of 5 J/g to 60 J/g. It is more preferably in the range of 10 J/g to 50 J/g, and most preferably in the range of 20 J/g to 40 J/g. By making the fusion heat (ΔH) of the acid-modified polyolefin (B) above the lower limit, the cohesive force derived from the crystallization becomes good, and excellent adhesion and solder heat resistance can be exhibited. In addition, by making the fusion heat (ΔH) of the acid-modified polyolefin (B) below the upper limit, the solution stability and fluidity are excellent, and the workability during bonding becomes good.

The method for producing the acid-modified polyolefin (B) is not particularly limited, and examples thereof include free radical grafting reaction (i.e., a free radical is generated for a polymer as a main chain, and the free radical is used as a polymerization starting point to graft an unsaturated carboxylic acid and anhydride).

There is no particular limitation on the free radical generator, and an organic peroxide is preferably used. There is no particular limitation on the organic peroxide, and examples thereof include di-tertiary butyl peroxyphthalate, tertiary butyl hydroperoxide, diisopropylbenzene peroxide, benzoyl peroxide, tertiary butyl peroxybenzoate, tertiary butyl peroxy-2-ethylhexanoate, tertiary butyl peroxypivalate, methyl ethyl ketone peroxide, di-tertiary butyl peroxide, lauryl peroxide and the like peroxides; and azonitriles such as azobisisobutylonitrile and azobisisopropionitrile.

[Epoxy resin (C)] The epoxy resin (C) (hereinafter also referred to as component (C)) used in the present invention is not particularly limited as long as it contains a glycidyl group in the molecule, but preferably contains two or more glycidyl groups in the molecule. Specifically, there is no particular limitation, and at least one selected from biphenyl type epoxy resin, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, alicyclic epoxy resin, dicyclopentadiene type epoxy resin, tetracyclyl diamino diphenyl methane, tricyclyl p-aminophenol, tetracyclyl bisamino methyl cyclohexanone, N,N,N',N'-tetracyclyl m-xylene diamine, and epoxy-modified polybutadiene can be used. Preferably, it is a biphenyl type epoxy resin, a novolac type epoxy resin, a dicyclopentadiene type epoxy resin or an epoxy-modified polybutadiene. More preferably, it is a dicyclopentadiene type epoxy resin or a novolac type epoxy resin.

The content of the epoxy resin (C) is preferably 0.1 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 1 parts by mass or more, and particularly preferably 2 parts by mass or more, relative to 100 parts by mass of the acid-modified polyolefin (B). By making the content of the epoxy resin (C) above the above lower limit, a sufficient curing effect can be obtained, and excellent adhesion and solder heat resistance can be exhibited. In addition, it is preferably 60 parts by mass or less, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and particularly preferably 35 parts by mass or less. By making the content of the epoxy resin (C) below the above upper limit, the low dielectric properties become good. That is, by setting the content of the epoxy resin (C) within the above range, an adhesive layer having excellent adhesion, solder heat resistance and low dielectric properties can be obtained.

The cured product of the acid-modified polyolefin (B) and the epoxy resin (C) (hereinafter also referred to as the cured product) is referred to as the cured product of the reaction of the components (B) and (C). When the entire adhesive layer is 100% by mass, it is preferred that the cured product contains 40% by mass or more. In order to improve the strength of the adhesive layer, it is preferred that the cured product contains 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 75% by mass or more.

The curing conditions of the components (B) and (C) are not particularly limited, but are preferably 100-200°C, more preferably 110-180°C, and more preferably 120-150°C. In addition, the curing time can be appropriately set, preferably about 1-10 hours, more preferably about 2-8 hours, and more preferably about 3-5 hours.

The curing component of the adhesive layer preferably further contains oligophenylene ether (D) and polycarbodiimide (E) having a number average molecular weight of 3000 or less.

[Oligophenyl ether (D)] The oligophenylene ether (D) used in the present invention (hereinafter also referred to as component (D)) has a mesh average molecular weight (Mn) of 3000 or less, and preferably a compound having a structural unit represented by the following general formula (1) and/or a structural unit represented by the general formula (2). By containing component (D), the solder heat resistance of the adhesive layer becomes good.

[Chemistry 1] In the general formula (1), _R1 , _R2 , _R3 , and _R4 are each independently preferably a hydrogen atom, an alkyl group which may be substituted, an alkenyl group which may be substituted, an alkynyl group which may be substituted, an aryl group which may be substituted, an aralkyl group which may be substituted, or an alkoxy group which may be substituted. The "alkyl" of the alkyl group which may be substituted is, for example, an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, in a linear or branched chain. More specifically, examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, dibutyl, tertiary butyl, pentyl, hexyl, etc., with methyl or ethyl being preferred. Examples of the "alkenyl" group which may be substituted include vinyl, 1-propenyl, 2-propenyl, 3-butenyl, pentenyl, hexenyl, etc., with vinyl or 1-propenyl being preferred. Examples of the "alkynyl" group which may be substituted include ethynyl, 1-propynyl, 2-propynyl (propargyl), 3-butynyl, pentynyl, hexynyl, etc., with ethynyl, 1-propynyl, or 2-propynyl (propargyl) being preferred. Examples of the "aryl" group which may be substituted include phenyl, naphthyl, etc., with phenyl being preferred. Examples of the "aralkyl" group which may be substituted include benzyl, phenethyl, 2-methylbenzyl, 4-methylbenzyl, α-methylbenzyl, 2-vinylphenethyl, 4-vinylphenethyl, etc., with benzyl being preferred. The "alkoxy" of the alkoxy group which may be substituted is, for example, an alkoxy group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, in a straight chain or branched chain. Examples include methoxy, ethoxy, propoxy, isopropoxy, butoxy, di-butoxy, tertiary butoxy, pentyloxy, hexyloxy, etc., with methoxy or ethoxy being preferred. When the above-mentioned alkyl, aryl, alkenyl, alkynyl, aralkyl, and alkoxy groups are substituted, they may have 1 or more substituents. Examples of such substituents include halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms), alkyl groups having 1 to 6 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, dibutyl, tertiary butyl, pentyl, hexyl), aryl groups (e.g., phenyl, naphthyl), alkenyl groups (e.g., vinyl, 1-propenyl, 2-propenyl), alkynyl groups (e.g., ethynyl, 1-propynyl, 2-propynyl), aralkyl groups (e.g., benzyl, phenethyl), alkoxy groups (e.g., methoxy, ethoxy), etc. Among them, _R1 and _R4 are preferably methyl groups, and _R2 and _R3 are preferably hydrogen.

[Chemistry 2] In the general formula (2), R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₅ , R ₁₆ , R ₁₇ , and R ₁₈ are each independently a hydrogen atom, an alkyl group which may be substituted, an alkenyl group which may be substituted, an alkynyl group which may be substituted, an aryl group which may be substituted, an aralkyl group which may be substituted, or an alkoxy group which may be substituted. In addition, the definitions of the substituents are as described above. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, dibutyl, tertiary butyl, pentyl, hexyl, etc., with methyl being preferred. Among them, R ₁₃ , R ₁₄ , R ₁₇ and R ₁₈ are methyl groups, and R ₁₁ , R ₁₂ , R ₁₅ and R ₁₆ are preferably hydrogen. In addition, -A- is preferably a linear, branched or cyclic divalent alkyl group with a carbon number of 20 or less, or oxygen. The carbon number of A is preferably 1 to 15, more preferably 2 to 10. In addition, examples of the divalent alkyl group of A include methylene, ethylene, n-propylene, n-butylene, cyclohexylene, phenylene, etc., among which phenylene is preferred. Oxygen is particularly preferred.

(D) component is part or all of it, and it can also be a modified polyphenylene ether functionalized by ethylenically unsaturated groups such as vinylbenzyl, epoxy, amino, hydroxyl, alkyl, carboxyl, and silyl. Furthermore, it is preferred that both ends have hydroxyl, epoxy, or ethylenically unsaturated groups. Ethylenically unsaturated groups can be exemplified by alkenyl groups such as vinyl, allyl, methacrylic, propenyl, butenyl, hexenyl, octenyl, cycloalkenyl such as cyclopentenyl, cyclohexenyl, vinylbenzyl, vinylnaphthyl, etc. alkenylaryl. In addition, both ends can be the same functional group or different functional groups. From the viewpoint of achieving a balance between high control of the loss tangent and reduction of the resin residue, it is preferred that both ends are hydroxyl groups or vinyl benzyl groups, and it is more preferred that both ends are hydroxyl groups or vinyl benzyl groups.

Among the compounds having the structural unit represented by the general formula (1), the compounds of the general formula (3) are particularly preferred. In the general formula (3), n is preferably 3 or more, more preferably 5 or more, preferably 23 or less, more preferably 21 or less, and even more preferably 19 or less.

In addition, among the compounds having the structural unit represented by the general formula (2), the compounds of the general formula (4) are particularly preferred. In the general formula (4), n is preferably 2 or more, more preferably 4 or more, preferably 23 or less, more preferably 20 or less, and even more preferably 18 or less.

The number average molecular weight of the component (D) must be 3000 or less, preferably 2700 or less, and more preferably 2500 or less. In addition, the number average molecular weight of the component (D) is preferably 500 or more, and more preferably 700 or more. By making the number average molecular weight of the component (D) above the lower limit, the flexibility of the adhesive layer can be improved. On the other hand, by making the number average molecular weight of the component (D) below the upper limit, the solubility in organic solvents can be improved.

The content of the component (D) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and more preferably 15 parts by mass or more, relative to 100 parts by mass of the component (B). In addition, it is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less. By making the content of the component (D) within the above range, an adhesive layer having excellent adhesion and solder heat resistance can be obtained.

<Polycarbodiimide (E)> The polycarbodiimide (E) used in the present invention (hereinafter also referred to as component (E)) is not particularly limited as long as it has a carbodiimide group in the molecule. It is preferably a polycarbodiimide having two or more carbodiimide groups in the molecule. By using polycarbodiimide, the carboxyl group of the acid-modified polyolefin (B) reacts with the carbodiimide group, which can enhance the interaction with the adhesive layer and the substrate, thereby improving the adhesion. In addition, the solder heat resistance of the adhesive layer becomes good.

The content of component (E) is preferably 0.5 parts by mass or more, preferably 1 part by mass or more, and more preferably 2 parts by mass or more relative to 100 parts by mass of component (B). By making the content of component (E) above the above lower limit, interaction with the substrate can be exhibited, and adhesion becomes good. In addition, it is preferably 20 parts by mass or less, preferably 15 parts by mass or less, and more preferably 10 parts by mass or less. By making the content of component (E) below the above upper limit, excellent dielectric properties can be exhibited. That is, by making the content of component (E) within the above range, an adhesive layer having adhesion and solder heat resistance, and excellent low dielectric properties can be obtained.

The adhesive layer of the present invention preferably has a relative capacitance (εc) of 3.0 or less at a frequency of 1 GHz. It is more preferably 2.6 or less, and more preferably 2.3 or less. Although the lower limit is not particularly limited, it is 2.0 in practice. In addition, the relative capacitance (εc) in the entire frequency range of 1 GHz to 30 GHz is preferably 3.0 or less, preferably 2.6 or less, and more preferably 2.3 or less.

The adhesive layer of the present invention preferably has a loss tangent (tanδ) of 0.02 or less at a frequency of 1 GHz. It is more preferably 0.01 or less, and more preferably 0.008 or less. Although the lower limit is not particularly limited, it is 0.0001 in practice. In addition, it is preferably 0.02 or less, more preferably 0.01 or less, and more preferably 0.05 or less in the entire frequency range of 1 GHz to 30 GHz.

In the present invention, the relative capacitance (εc) and the loss tangent (tanδ) can be measured as follows. For example, a metal layer can be formed on both sides of an adhesive layer by a thin film method such as vapor deposition or sputtering deposition, or by coating a conductive paste, etc. to serve as a capacitor, and the electrostatic capacitance can be measured. The relative capacitance (εc) and the loss tangent (tanδ) can be calculated from the thickness and area. In addition, when measuring the relative capacitance and loss tangent of the adhesive layer from a laminate, the metal substrate and/or the resin substrate may be removed for measurement, or the laminate, adhesive layer/metal substrate or adhesive layer/resin substrate may be maintained for measurement, and then the relative capacitance and loss tangent values of the metal substrate and/or the resin substrate may be subtracted.

<Resin substrate> The resin substrate is not particularly limited to any resin material substrate that can be used to form a laminate after being coated with an adhesive composition and dried. Examples include polyester resins, polyamide resins, polyimide resins, polyamide-imide resins, liquid crystal polymers, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resins, and fluorine resins. Film-like resins are preferred.

The thickness of the resin substrate is not particularly limited. From the perspective of improving the strength of the laminate, it is preferably 5 μm or more, more preferably 10 μm or more, and more preferably 20 μm or more. In addition, from the perspective of improving the processing efficiency when manufacturing the circuit, it is preferably 200 μm or less, more preferably 100 μm or less, and more preferably 50 μm or less.

<Metal substrate> The metal substrate can be any conventionally known conductive material that can be used on a circuit board. Examples of the material include various metals such as SUS, copper, aluminum, iron, steel, zinc, nickel, and their respective alloys, plated products, and metals treated with other metals such as zinc and chromium compounds. Metal foil is preferred, and copper foil is more preferred.

The thickness of the metal substrate is not particularly limited. From the perspective of obtaining sufficient electrical performance of the circuit, it is preferably 1 μm or more, more preferably 3 μm or more, and more preferably 10 μm or more. In addition, from the perspective of improving processing efficiency when manufacturing the circuit, it is preferably 50 μm or less, more preferably 30 μm or less, and more preferably 20 μm or less.

The metal substrate is usually provided in a roll form. There is no particular restriction on the form of the metal substrate used in manufacturing the printed circuit board of the present invention. When a metal substrate (metal foil) in a strip form is used, there is no particular restriction on its length. In addition, although there is no particular restriction on its width, it is preferably about 250 to 500 cm.

The metal substrate may be subjected to surface treatment. Examples of surface treatment include ITRO treatment, plasma treatment, sandblasting treatment, primer treatment, and adhesive treatment.

<Printed circuit board> The printed circuit board in the present invention includes the laminate of the present invention as a constituent element. The printed circuit board is manufactured by a conventionally known method such as a subtractive method using a metal-clad laminate. It is a general term for so-called flexible printed circuits (FPCs), flat cables, and tape automated bonding (TAB) circuit boards, which are partially or entirely coated with a metal foil conductive circuit using a surface coating, screen printing ink, etc. as needed.

The printed circuit board of the present invention can be manufactured into any laminated structure that can be used as a printed circuit board. For example, it can be a printed circuit board composed of a laminate (resin substrate/adhesive layer/metal substrate)/adhesive layer/surface coating layer.

<Examples> The following examples are given to illustrate the present invention in more detail. However, the present invention is not limited to the examples. In the examples and comparative examples, "parts by mass" is abbreviated as "parts".

(Physical property evaluation method)

Acid value: acid-modified polyolefin (B) The acid value (mgKOH/g) in the present invention is obtained by dissolving the acid-modified polyolefin (B) in toluene, using phenolphthalein as an indicator, and titrating with a methanol solution of sodium methoxide.

Number average molecular weight (Mn) The number average molecular weight in the present invention is the value measured by a gel chromatograph manufactured by Shimadzu Corporation (hereinafter referred to as GPC, standard material: polystyrene resin, mobile phase: tetrahydrofuran, column: Shodex KF-802 + KF-804L + KF-806L, column temperature: 30°C, flow rate: 1.0 ml/min, detector: RI detector).

Melting point, heat of fusion The melting point and heat of fusion in the present invention are measured by using a differential scanning calorimeter (hereinafter referred to as DSC, manufactured by TA Instruments Japan, Q-2000), heating at a rate of 20°C/min to melt, cooling to resinify, and then heating again to melt and measure the peak temperature and area of the melting peak.

Peel strength (adhesion) The following adhesive composition b was applied to a 12.5 μm thick polyimide film (manufactured by Kaneka Co., Ltd., APICAL (registered trademark)) in such a manner that the thickness after drying was 12.5 μm, and dried at 130°C for 3 minutes. Then, the adhesive composition a was applied to the adhesive composition b surface in such a manner that the thickness after drying was 12.5 μm, and dried at 130°C for 3 minutes. The adhesive film (B-stage product) obtained in this manner was bonded to a 18 μm thick rolled copper foil (manufactured by JX Metal Co., Ltd., BHY series). The bonding is done by bringing the smooth surface of the rolled copper foil into contact with the adhesive layer at 160°C and under a pressure of 40kgf/ ^cm2 for 30 seconds. It is then hardened by heat treatment at 140°C for 4 hours to obtain a sample for peel strength evaluation. The sample for peel strength evaluation is subjected to a 90° peel test at 25°C and a tensile speed of 50mm/min to measure the peel strength. This test indicates the bonding strength at room temperature. [Evaluation Standard] ◎: 1.0N/mm or more ○: 0.8N/mm or more but less than 1.0N/mm △: 0.5N/mm or more but less than 0.8N/mm ×: less than 0.5N/mm

Solder heat resistance The samples were prepared in the same way as the peel strength test. The 2.0 cm × 2.0 cm sample pieces were aged at 23°C for 2 days and floated in a solder bath melted at 280°C for 10 seconds to check for changes in appearance such as expansion. <Evaluation criteria> ◎: No expansion ○: Some expansion △: Some expansion ×: Expansion and discoloration

Relative capacitance (εc) and loss tangent (tanδ) The following adhesive composition b was applied to a 100μm thick Teflon (registered trademark) sheet in such a way that the thickness after drying and curing became 12.5μm, and dried at 130℃ for 3 minutes. Then, adhesive composition a was applied to the adhesive composition b surface in such a way that the thickness after drying became 12.5μm, and dried at 130℃ for 3 minutes. Then, after heat treatment at 140℃ for 4 hours to harden it, the Teflon (registered trademark) sheet was peeled off to obtain a test adhesive layer sheet. The obtained test adhesive layer sheet was cut into short pieces of 8cm×3mm to obtain a test sample. Relative capacitance (εc) and loss tangent (tanδ) were measured using a network analyzer (manufactured by Anritsu Corporation) using the cavity resonator perturbation method at a temperature of 23°C and a frequency of 1 GHz. The relative capacitance and loss tangent were evaluated as follows. ＜Evaluation criteria for relative capacitance＞ ◎: 2.3 or less ○: More than 2.3, less than 2.6 △: More than 2.6, less than 3.0 ×: More than 3.0 ＜Evaluation criteria for loss tangent＞ ◎: 0.008 or less ○: More than 0.008, less than 0.01 △: More than 0.01, less than 0.02 ×: More than 0.02

Number of fillers (A) The laminate was cut perpendicular to the surface of the laminate, and the cross section was photographed with an electron microscope. The fillers contained in the adhesive layer 3a and the adhesive layer 3b in the cross section were visually counted. In addition, fillers (A) with a length smaller than 15 nm were not included in the calculation because the linear expansion property had a weak effect.

Linear expansion Using a thermomechanical analyzer (manufactured by Hitachi High-Tech Science, "TMA-7100"), the test sample with a total film thickness of 25μm used in the above relative capacitance measurement was cut into a length of 1.5cm and introduced into the device. The temperature was raised from 20℃ to 250℃ under the conditions of a load of 5g and a heating rate of 10℃/min. Based on the obtained temperature and dimensional change data, the average linear expansion coefficient at 30℃ was calculated to evaluate the low expansion of the test sample. ＜Evaluation standard of linear expansion coefficient＞ The evaluation standard is the value at 30℃. ◎: 500ppm or less ○: More than 500ppm, less than 550ppm △: More than 550ppm, less than 600ppm ×: More than 600ppm

Preparation Example of Resin Composition (F-1) 30 parts by mass of filler (A-1), 100 parts by mass of acid-modified polyolefin (B-1), 20 parts by mass of epoxy resin (C-1), 382 parts by mass of methylcyclohexane, 39 parts by mass of methyl ethyl ketone, and 11 parts by mass of toluene were mixed and stirred uniformly to obtain a resin composition (F-1).

Preparation example of resin composition (F-2)~(F-23) Resin composition (F-2)~(F-23) was prepared in the same manner as resin composition (F-1). The blending amount is shown in Table 1.

Example 1 The resin composition (F-12) was applied to a polyimide (PI) film (Kapton EN50, manufactured by DU PONT-TORAY) to a thickness of 12.5 μm after drying, and dried at 130°C for 3 minutes. Then, the resin composition (F-11) was applied to a thickness of 12.5 μm after drying, and dried at 130°C for 3 minutes. Then, a copper foil (BHY, thickness 18 μm, manufactured by JX Japan Mining and Sunshine Co., Ltd.) was attached so that the smooth surface thereof was in contact with the resin composition (F-11) layer, and the layers were bonded by applying pressure at 160°C and 40 kgf/ ^cm2 for 30 seconds. Then, the laminate was cured by heat treatment at 140°C for 4 hours. The ratio of the number of fillers (A) contained in the adhesive layer 3a and the adhesive layer 3b was a1/a2=52/48 (30/28). The results are shown in Table 2.

Examples 2 to 13, Comparative Examples 1 to 3 Examples 2 to 13 and Comparative Examples 1 to 3 were carried out in the same manner as Example 1. The results are shown in Table 2.

[Table 1]

[Table 2]

The filler (A), acid-modified polyolefin (B), epoxy resin (C), oligophenylene ether (D) and polycarbodiimide (E) used in Table 1 are as follows: <Filler (A)> Filler (A-1): phosphorus-based flame retardant filler (HCA-HQ-HS manufactured by Sanko Co., Ltd., spherical, particle size: 1.5μm) Filler (A-2): aluminum hydroxide (HYGILITE H42M manufactured by Showa Denko Co., Ltd., particle size: 1.0μm) Filler (A-3): silicon oxide (FB-3SDC manufactured by Denka Co., Ltd., spherical, particle size: 3μm) Filler (A-4): titanium oxide (TIPAQUE manufactured by Ishihara Sangyo Co., Ltd.) CR-50, particle size: 0.25μm) Filler (A-5): Carbon black (Mitsubishi Chemical Co., Ltd. Carbon black good fluidity #MA100, spherical, particle size: 24nm) <Epoxy resin (C)> Epoxy resin (C-1): Dicyclopentadiene type epoxy resin: HP-7200 (DIC Corporation, epoxy equivalent 259g/eq) Epoxy resin (C-2): Epoxy-modified polybutadiene resin: JP-100 (Nippon Soda Co., Ltd.) <Oligophenyl ether (D)> Oligophenyl ether (D-1): Oligophenyl ether styrene modified product: OPE-2St 1200 (Mitsubishi Gas Chemical Co., Ltd. =Compound with a structure of general formula (4) with Mn 1000) Oligophenyl ether (D-2): Oligophenyl ether: SA90 (Compound with a structure of general formula (3) with Mn 1800 manufactured by SABIC) <Polycarbodiimide (E)> Polycarbodiimide resin (E-1): V-09GB (manufactured by Nisshinbo Chemical Co., Ltd., carbodiimide equivalent 216 g/eq)

<Acid-modified polyolefin (B)> Production Example 1 In a 1L autoclave, 100 parts by mass of propylene-butene copolymer ("TAFMER (registered trademark) XM7080" manufactured by Mitsui Chemicals Co., Ltd.), 150 parts by mass of toluene, 19 parts by mass of maleic anhydride, and 6 parts by mass of di-tertiary butyl peroxide were added, and the temperature was raised to 140°C, followed by stirring for 3 hours. After that, the obtained reaction liquid was cooled and poured into a container containing a large amount of methyl ethyl ketone to precipitate the resin. Thereafter, by centrifugally separating the liquid containing the resin, the acid-modified propylene-butene copolymer grafted with maleic anhydride was separated from the (poly)maleic anhydride and low molecular weight substances and purified. After that, the mixture was dried at 70°C for 5 hours under reduced pressure to obtain a maleic anhydride-modified propylene-butene copolymer (B-1, acid value 19 mgKOH/g, number average molecular weight 25,000, Tm 80°C, ΔH 35 J/g).

Preparation Example 2 Except that the amount of maleic anhydride added was changed to 6 parts by mass, a maleic anhydride-modified propylene-butene copolymer (B-2, acid value 7 mgKOH/g, number average molecular weight 35,000, Tm 82°C, ΔH 25 J/g) was obtained in the same manner as in Preparation Example 1. [Industrial Applicability]

The laminate of the present invention has good adhesion and dielectric properties, and good linear expansion properties, and is useful in the application of flexible printed circuit boards, especially in FPC applications that require low dielectric properties (low relative capacitance, low loss tangent) in the high frequency region.

1: Metal substrate 2: Resin substrate 3: Adhesive layer 3a: Adhesive layer 3a 3b: Adhesive layer 3b 10: Laminated body

[Figure 1] Figure 1 is a cross-sectional view in a direction perpendicular to the surface of the laminate.

1:Metal substrate

2: Resin substrate

3: Adhesive layer

3a: Adhesive layer 3a

3b: Adhesive layer 3b

10:Layered body

Claims (5)

A laminated body is a metal substrate, an adhesive layer, and a resin substrate laminated in sequence, wherein the adhesive layer contains a filler (A), an acid-modified polyolefin (B), and a cured product of an epoxy resin (C); the filler (A) is selected from at least one of the group consisting of a phosphorus-containing flame retardant filler, aluminum hydroxide, silicon oxide, titanium oxide, and carbon black; and the content of the filler (A), relative to 100 parts by weight of the acid-modified polyolefin (B), is 0.1 mass parts or more and 50 mass parts or less; in the cross section of the adhesive layer in the direction perpendicular to the surface of the laminate, the number a1 of the filler (A) contained in the area from the midpoint to the side close to the surface of the metal substrate is greater than the number b1 of the filler (A) contained in the area from the midpoint to the side close to the surface of the resin substrate, and the ratio of a1 to b1 is a1/b1=98/2~52/48. As in claim 1, the laminated body, wherein the curing component of the adhesive layer further contains oligophenylene ether (D) with a numerical average molecular weight of less than 3000. As in claim 1 or 2, the laminated body, wherein the curing component of the adhesive layer further contains polycarbodiimide (E). A laminate as claimed in claim 1 or 2, wherein the relative capacitance (εc) of the adhesive layer at 1 GHz is less than 3.0, and the loss tangent (tanδ) is less than 0.02. A printed circuit board comprising a laminated body as one of claims 1 to 4.