JP5494914B2 - Adhesive sheet and multilayer printed circuit board obtained using the adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet and a multilayer printed board obtained using the adhesive sheet.

As portable electronic devices such as mobile PCs, mobile phones, and IC cards rapidly spread, in applications such as FPC (flexible printed circuit board) and COF (chip-on-film) obtained using polyimide film As the density of electronic substrates increases and the number of layers increases, the dimensional stability of the insulating layer is increasingly required.

In addition, in the field of multilayer printed circuit boards on which ICs are mounted, epoxy adhesive films are generally used as interlayer insulating materials. However, as density increases in this field, interlayer insulating layers are required to have heat resistance and low thermal expansion. It is getting to be.

  In response to such needs, an epoxy adhesive film has been proposed as an interlayer insulating layer adhesive film excellent in low thermal expansion and rigidity (see Patent Documents 1 and 2). However, even if the adhesive film is used, it cannot be said that the low thermal expansion property is sufficient, and the effect is not sufficient in a printed wiring board having a high density because it exhibits high thermal expansion particularly in a high temperature environment. .

  On the other hand, a two-layer adhesive sheet composed of a polyimide film and an adhesive layer has been proposed (see Patent Document 3). In this case as well, a silicon wafer (thermal expansion coefficient 3 to 4 ppm) used for an IC and an adhesive sheet are used. Due to the difference in thermal expansion coefficients, the low thermal expansion was not satisfactory.

In the future, in these precision printed circuit boards, it is estimated that the number of layers will increase, and there is a strong demand for ensuring heat resistance and low thermal expansion in an environment where heating and cooling are repeated.

JP-A-10-298508 Japanese Patent Laid-Open No. 11-323272 International Publication No. 2005/027597

  An object of this invention is to provide the adhesive sheet which has adhesiveness, heat resistance, and low thermal expansibility, and the high-density multilayer printed circuit board obtained using the said adhesive sheet.

  As a result of intensive studies, the present inventors can solve the above problems by using an epoxy resin adhesive cured film layer having a specific storage elastic modulus on a polyimide film having a specific storage elastic modulus. I found.

  That is, the present invention has a storage elastic modulus at 150 ° C. of 2.0 MPa to 0.2 GPa on a polyimide film (1) having a storage elastic modulus of 2 to 10 GPa at 150 ° C. and a thermal expansion coefficient of 0 to 6 ppm. An adhesive sheet having a thermal expansion coefficient of 10 ppm or less, provided with an epoxy resin adhesive cured film layer (2), and a multilayer printed board obtained by subjecting the adhesive sheet to electroless plating

According to the present invention, it is possible to obtain an adhesive sheet that has adhesion, heat resistance, and low thermal expansion (particularly low thermal expansion under a high temperature environment) and can be multilayered. Further, the adhesive sheet of the present invention can be made flame retardant VTM-0 according to UL standards even when a halogen-based flame retardant is used or a halogen-containing compound is not used as a raw material.

The adhesive sheet of the present invention has a storage elastic modulus at 150 ° C. of 2.0 MPa to 0.00 on a polyimide film (1) having a storage elastic modulus of 2 to 10 GPa at 150 ° C. and a thermal expansion coefficient of 0 to 6 ppm. The epoxy resin adhesive cured film layer (2) of 2 GPa is provided, and the thermal expansion coefficient is 10 ppm or less.

The polyimide film (1) used in the present invention is not particularly limited as long as it is a non-thermoplastic polyimide film satisfying the conditions of a storage elastic modulus of 2 to 10 GPa and a thermal expansion coefficient of 0 to 6 ppm, and a conventionally known polyimide film is used. It can be used as it is. When the thermal expansion coefficient exceeds 6, it is not preferable in that a low thermal expansion sufficient for an interlayer insulating material cannot be obtained. Further, when the elastic modulus is less than 2 GPa, it is not preferable in that it may be blocked, and when it exceeds 10 GPa, it is not preferable because flexibility is lost and cracks may occur. Here, the storage elastic modulus is a storage at 150 ° C. when a polyimide film having a film thickness of 25 μm is measured with a dynamic viscoelasticity measuring device (distance between chucks: 10 mm, specimen width: 5 mm, frequency: 10 Hz). It is a value of elastic modulus, and the coefficient of thermal expansion is measured using a thermomechanical analyzer (distance between chucks: 20 mm, specimen width: 4 mm, load: 10 mg, temperature rising rate: 10 ° C./min tensile mode). Means a value between 100 ° C and 200 ° C.

As a method for producing such a polyimide film, for example, conventionally known methods described in JP-A-5-70590, JP-A-2000-119419, JP-A-2007-56198, JP-A-2005-68408, and the like. The method is mentioned. Moreover, as a commercially available polyimide film, Toyobo Co., Ltd. XENOMAX, Arakawa Chemical Industries Co., Ltd. Pomilan T, etc. can be mentioned.

Among the polyimide films mentioned above, block copolymerization is possible due to the adhesion to the cured epoxy resin adhesive film layer (2) during multilayering, metallization such as plating and sputtering, and dimensional stability. A polyimide-silica hybrid film (as a commercial product, for example, trade name Pomilan T manufactured by Arakawa Chemical Industries, Ltd.) is most preferable.

The block copolymer polyimide-silica hybrid film can be obtained by thermally curing an alkoxy group-containing silane-modified block copolymer polyamic acid by the method of JP-A-2005-68408. The alkoxy group-containing silane-modified block copolymer type polyamic acid (b) (hereinafter referred to as component (b)) is, for example, a polyamic acid obtained by reacting tetracarboxylic dianhydride and diamine with an epoxy group-containing alkoxysilane moiety. Separately, polyamic acid (a) obtained by reacting the condensate (hereinafter referred to as component (a)) is mixed with polyamic acid obtained by reacting tetracarboxylic dianhydride and diamine, and condensed. Can be obtained. The segment of component (a) has an alkoxysilane partial condensate in the side chain and forms silica by a sol-gel reaction. Separately, the segment of polyamic acid obtained by reacting tetracarboxylic dianhydride and diamine does not have silica, and exhibits high elastic modulus and low thermal expansion of block copolymer type polyimide-silica hybrid film. Contribute to.

At this time, if the tetracarboxylic dianhydride and diamine constituting the polyamic acid are adjusted in their kind and amount so that the elastic modulus of the polyimide film is 2 to 10 GPa and the thermal expansion coefficient is 0 to 6 ppm, Conventionally known ones can be used.

Examples of the tetracarboxylic dianhydride used for the preparation of the component (a) and the component (b) include pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 1,4 , 5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 3 , 3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,3,3 ′, 4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenyl ether tetracarboxylic dianhydride Anhydride, 2, , 3 ′, 4′-diphenyl ether tetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenyl sulfone tetracarboxylic dianhydride, 2,3,3 ′, 4′-diphenyl sulfone tetracarboxylic dianhydride Anhydride, 2,2-bis (3,3 ′, 4,4′-tetracarboxyphenyl) tetrafluoropropane dianhydride, 2,2′-bis (3,4-dicarboxyphenoxyphenyl) sulfone dianhydride 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, cyclopentanetetracarboxylic dianhydride, butane- Examples thereof include 1,2,3,4-tetracarboxylic acid and 2,3,5-tricarboxycyclopentylacetic acid dianhydride.

  The diamines used for the preparation of component (a) and component (b) include 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminophenylmethane, and 3,3′-dimethyl. -4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-di (m-aminophenoxy) diphenylsulfone, 4,4'-diaminodiphenyl sulfide, 1,4-diaminobenzene, 2 , 5-diaminotoluene, isophoronediamine, 4- (2-aminophenoxy) -1,3-diaminobenzene, 4- (4-aminophenoxy) -1,3-diaminobenzene, 2-amino-4- (4- Aminophenyl) thiazole, 2-amino-4-phenyl-5- (4-aminophenyl) thiazole, benzi 3,3 ′, 5,5′-tetramethylbenzidine, octafluorobenzidine, o-tolidine, m-tolidine, p-phenylenediamine, m-phenylenediamine, 1,2-bis (anilino) ethane, 2, 2-bis (p-aminophenyl) propane, 2,2-bis (p-aminophenyl) hexafluoropropane, 2,6-diaminonaphthalene, diaminobenzotrifluoride, 1,4-bis (p-aminophenoxy) benzene 4,4′-bis (p-aminophenoxy) biphenyl, diaminoanthraquinone, 1,3-bis (anilino) hexafluoropropane, 1,4-bis (anilino) octafluoropropane, 2,2-bis [4- (P-aminophenoxy) phenyl] hexafluoropropane and the like can be exemplified. Among these diamines, p-phenylenediamine is particularly effective for lowering the thermal expansion coefficient, so about 60 to 100 mol% of the diamine contained in component (b) is p-phenylenediamine. It is preferable.

  (A) Manufacture of the polyamic acid used as the raw material of the component is to be manufactured at a polyimide-converted solid residue of 5 to 60% in an organic solvent that dissolves the generated polyamic acid and the epoxy group-containing alkoxysilane partial condensate described later. Is preferred. Here, the polyimide-converted solid residue represents the weight percent of the polyimide with respect to the polyamic acid solution when the polyamic acid is completely cured into polyimide. If the polyimide conversion solid residue is less than 5%, the production cost of the polyamic acid solution is increased. On the other hand, when it exceeds 60%, the polyamic acid solution has a high viscosity at room temperature, so that the handling tends to be poor. Examples of the organic solvent to be used include dimethyl sulfoxide, diethyl sulfoxide, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, Organic polar solvents such as N-vinyl-2-pyrrolidone, phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, catechol, hexamethylphosphoramide, γ-butyrolactone, and the like. Are preferably used alone or as a mixture, but aromatic hydrocarbons such as xylene and toluene can be used in combination with the polar solvent. Among these, dimethyl sulfoxide, diethyl sulfoxide, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, N-vinyl It is preferred to use 2-pyrrolidone alone or as a mixture.

  The reaction temperature is not particularly limited as long as the amic acid group remains, but is preferably adjusted to about -20 to 80 ° C. Production below −20 ° C. is uneconomical because the reaction rate is slow and requires a long time, and when it exceeds 80 ° C., the ratio of the amide group in the polyamic acid ring-closing to the imide group increases, and the epoxy group The reaction point with the contained alkoxysilane partial condensate tends to decrease, which is not preferable.

  The epoxy group-containing alkoxysilane partial condensate used when preparing the component (a) is obtained, for example, by a dealcoholization reaction between an epoxy compound having one hydroxyl group in one molecule and an alkoxysilane partial condensate. The number of epoxy groups is not particularly limited as long as the epoxy compound is an epoxy compound having one hydroxyl group in one molecule. In addition, as the epoxy compound, the smaller the molecular weight, the better the compatibility with the alkoxysilane partial condensate, and the higher the heat resistance and adhesion imparting effect. It is preferable to use glycidol or epoxy alcohol. In addition, you may use the product name "Epiol OH" by Nippon Oil & Fats Co., Ltd., the product name "EOA" by Kuraray Co., Ltd., etc.

As the alkoxysilane partial condensate, general formula (2): R ¹ _m Si (OR ² ) _(4-m) (wherein R ¹ is an alkyl group or aryl group having 8 or less carbon atoms, and R ² is carbon number) A hydrolyzable alkoxysilane monomer represented by an alkyl group of 4 or less, m is an integer of 0 or 1, and is partially condensed by hydrolysis in the presence of an acid or base catalyst and water. What is obtained is used.

Specific examples of the hydrolyzable alkoxysilane monomer that is a constituent raw material of the alkoxysilane partial condensate include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, methyltrimethoxysilane, Such as methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane And trialkoxysilanes. Among these, since the reactivity with an epoxy compound having one hydroxyl group in one molecule is particularly high, the alkoxysilane partial condensate is synthesized using tetramethoxysilane or methyltrimethoxysilane in an amount of 70 mol% or more. The ones made are preferred.

In addition, as these alkoxysilane partial condensates, those exemplified above can be used without any particular limitation. However, when two or more of these examples are mixed and used, tetraalkoxysilane in the total amount of the alkoxysilane partial condensate is used. It is preferable to use 70% by weight or more of a methoxysilane partial condensate or a methyltrimethoxysilane partial condensate.

The number average molecular weight of the alkoxysilane partial condensate is preferably about 230 to 2000, and the average number of Si in one molecule is preferably about 2 to 11.

The epoxy group-containing alkoxysilane partial condensate is obtained by dealcoholizing an epoxy compound having one hydroxyl group in one molecule and an alkoxysilane partial condensate. The use ratio of the epoxy compound and the alkoxysilane partial condensate is not particularly limited as long as the alkoxy group substantially remains, but the ratio of the epoxy group in the obtained epoxy group-containing alkoxysilane partial condensate is not limited. Usually, the equivalent of the hydroxyl group of the epoxy compound having one hydroxyl group in one molecule / the equivalent of the alkoxy group of the alkoxysilane partial condensate = the charge ratio of about 0.01 / 1 to 0.3 / 1, the alkoxy It is preferable to subject the silane condensate and an epoxy compound having one hydroxyl group in one molecule to a dealcoholization reaction. Since the ratio of the alkoxysilane partial condensate which is not epoxy-modified increases and the block copolymerization type polyimide-silica hybrid film tends to become opaque when the charging ratio decreases, the charging ratio is 0.03 or more / More preferably, it is about 1.

In the reaction of the alkoxysilane partial condensate and the epoxy compound having one hydroxyl group in one molecule, for example, the above-described components are charged and the alcohol is generated by distilling off the alcohol produced by heating. The reaction temperature is about 50 to 150 ° C., preferably 70 to 110 ° C., and the total reaction time is about 1 to 15 hours.

The component (a) is obtained by reacting the polyamic acid with the epoxy group-containing alkoxysilane partial condensate. The use ratio of the polyamic acid and the epoxy group-containing alkoxysilane partial condensate is not particularly limited. (Equivalent of epoxy group of epoxy group-containing alkoxysilane partial condensate / tetracarboxylic dianhydride (A) used for polyamic acid) Is preferably in the range of 0.01 to 0.6. If the above numerical value is less than 0.01, it is difficult to obtain the effect of the present invention, and if it exceeds 0.6, the polyimide-silica hybrid film tends to be opaque, which is not preferable.

The component (b) is obtained by reacting the component (a) with the tetracarboxylic dianhydride and diamine. In addition, it is preferable that the tetracarboxylic dianhydride and diamine used when preparing (b) component differ from what was used when preparing (a) component. The reaction conditions for obtaining the component (b) may be the same as the conditions for preparing the component (a). Although the molecular weight of (b) component is not specifically limited, It is preferable that a number average molecular weight (The polystyrene conversion value by a gel permeation chromatography method) is about 10,000-1 million.

  As a method for producing the polyimide film (1) from the component (b), JP-A-5-70590, JP-A-2000-119419, JP-A-2007-56198, JP-A-2005-68408, etc. However, from the viewpoint of obtaining productivity and low thermal expansion, it is preferable to use a curing method using a catalyst. Specifically, for example, as described in JP-A-5-70590, a solution obtained by adding a dehydrating agent of a stoichiometric amount or more and a catalytic amount of a tertiary amine to the polyamic acid polymer or a solution thereof is endless. The film is cast or coated on a belt to form a film, and the film is dried at a temperature of 150 ° C. or lower for about 5 to 90 minutes to obtain a self-supporting polyamic acid film, which is then peeled off from the support. After fixing an edge part, it is made to imidize by gradually heating to about 100-500 degreeC, It removes from a drum or an endless belt after cooling, and the method of obtaining the polyimide film of this invention is employable. Examples of the dehydrating agent herein include aliphatic acid anhydrides such as acetic anhydride and aromatic acid anhydrides such as benzoic anhydride. Examples of the catalyst include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, and heterocyclic tertiary amines such as pyridine, picoline, and isoquinoline.

The epoxy adhesive cured film layer used in the adhesive sheet of the present invention is a cured film obtained only from the epoxy resin composition layer, and the storage elastic modulus at 150 ° C. needs to be 2.0 MPa to 0.2 GPa. is there. In addition, the cured film which consists only of the epoxy resin layer used when measuring storage elastic modulus is epoxy-bonded on a separate PET film (trade name: Purex film thickness 25 μm, manufactured by Teijin DuPont Films, Ltd.) subjected to silicone treatment. The adhesive composition used as the base of the cured agent film layer is applied so that the cured film thickness is 25 μm, dried at 140 ° C. for 3 minutes, fixed to a 50 mm × 70 mm metal fitting, and at 190 ° C. for 60 minutes in an oven. It is obtained by curing. Moreover, the measuring method of an elasticity modulus is the same as the measuring method of said polyimide film.

The adhesive composition of the present invention usually comprises an epoxy resin (A) (hereinafter referred to as component (A)), an epoxy curing agent (B) (hereinafter referred to as component (B)), an elastomer (C) (hereinafter referred to as component (A)). (Referred to as component (C)) and flame retardant (D) (hereinafter referred to as component (D)).

(A) It does not specifically limit as a component, A conventionally well-known epoxy resin can be used. Bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin and the like can be exemplified, and a plurality of types of epoxy resins may be mixed and used. As the molecular weight of these epoxy resins, those having a molecular weight of 300 or more and less than 2000 are particularly preferable because they have good penetration into the circuit.

When the alkoxy group-containing silane-modified epoxy resin described in JP-A-2001-59013 is partially used as the component (A), the surface tack of the epoxy adhesive cured film layer in a semi-cured state is reduced, and the circuit This is more preferable because adhesion with copper forming the film is improved. The proportion of the alkoxy group-containing silane-modified epoxy resin used relative to the component (A) is preferably about 0.5 to 50% by weight. If it exceeds 50% by weight, the penetration into the circuit tends to deteriorate.

As the component (B), a conventionally known curing agent having latency can be used. For example, examples of the amine curing system include dicyandiamide (DICY) and aromatic diamine. Examples of the phenol curing system include a phenol novolak resin, a cresol novolak resin, a bisphenol A type novolak resin, and a triazine-modified phenol novolak resin. . These can be used individually or in mixture of 2 or more types.

  As (C) component used for this invention, if an epoxy resin composition layer is made into a low elasticity modulus and heat resistance is not impaired, a well-known thing can be used without a restriction | limiting. Examples thereof include various synthetic rubbers such as acrylic rubber, acrylonitrile butadiene rubber and carboxyl group-containing acrylonitrile butadiene rubber, rubber-modified high molecular weight compounds and the like, and these can be used alone or in combination of two or more. In view of excellent adhesion to the polyimide film (1), it is preferable to use acrylic rubber or carboxyl group-containing acrylonitrile butadiene rubber. When the glass transition temperature of the component (C) is 20 ° C. or lower, it is more preferable that the elastic modulus hardly changes at room temperature or higher.

  Examples of the component (D) include conventionally known inorganic filler flame retardants and non-halogen flame retardants such as phosphorus, and these may be used in combination. Examples of the inorganic filler-based flame retardant include aluminum hydroxide, magnesium hydroxide, talc, silica, alumina, zinc borate, calcium carbonate, and the like, but in the case of a fine pitch circuit used for a high-density printed circuit board, In order to maintain insulation between conductors, it is preferable to use those having an average particle diameter of about 0.1 μm to 5 μm. Examples of the phosphorus-based flame retardant include polyphosphoric acid, phosphoric acid ester, phosphazene derivatives, and the like, but those that are solid at room temperature are preferable because they do not adversely affect heat resistance and adhesion. Although the usage-amount of a flame retardant is not specifically limited, It is preferable to use about 30 to 70 weight% in solid content of an adhesive composition for the use for which nonflammability is calculated | required.

In addition to the above components, the adhesive composition includes a curing catalyst, a solvent, an inorganic filler, a silane coupling agent, a leveling agent, a release agent, a surface treatment agent, and a viscosity modifier as long as the effects of the present invention are not impaired. Plasticizers, antibacterial agents, antifungal agents, antifoaming agents, colorants, stabilizers, coupling agents, and the like may be blended.

The curing catalyst can accelerate the curing reaction between the component (A) and the component (B), lower the temperature of curing performed after bonding, and shorten the curing time. For example, tertiary amines such as 1,8-diaza-bicyclo [5.4.0] undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl) phenol; 2 -Imidazoles such as methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole, 1-cyanoethyl-2-undecylimidazole; tributylphosphine, methyldiphenylphosphine, triphenylphosphine, Organic phosphines such as diphenylphosphine and phenylphosphine; tetraphenylphosphonium tetraphenylborate, 2-ethyl-4-methylimidazole tetraphenylborate, N-methylmol Such as tetraphenyl boron salts such as phosphorus-tetraphenylborate and the like. The curing accelerator is preferably used at a ratio of about 0.05 to 5% by weight with respect to the component (A).

The solvent is used for adjusting the viscosity of the adhesive composition. For example, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, ester solvents such as ethyl acetate, butyl acetate, cellosolve acetate, methyl cellosolve acetate, aromatic solvents such as toluene, xylene, tetrahydrofuran, diethylene glycol dimethyl ether, etc. Examples include ether solvents, alcohols such as isopropyl alcohol and n-butyl alcohol, and aprotic polar solvents such as dimethylformamide. In these, since it is hard to remain | survive in a semi-hardened epoxy adhesive cured film layer, it is preferable to use a thing with a boiling point of about 70-150 degreeC. In addition, the mixture ratio of a solvent is not specifically limited, What is necessary is just to determine suitably according to the coating method of an adhesive composition.

In the present invention, the use ratio of each component constituting the adhesive composition is not particularly limited, but when the component (C) is 5 to 50% by weight in the solid content of the adhesive composition, the cured film at 150 ° C. The elastic modulus tends to be in the range of 2.0 MPa to 0.2 GPa, and tends to be a low thermal expansion adhesive sheet.

The said adhesive composition can be normally hardened | cured by heating after apply | coating to a base material, and can be used as an epoxy adhesive cured film layer (2). In addition, in hardening, after hardening at about 70-150 degreeC first, it is the point which suppresses the adhesive force fall by rapid hardening shrinkage by setting it as hardening in about 150-250 degreeC. To preferred. The curing time is not particularly limited and can be adjusted by the film thickness of the epoxy adhesive cured film layer (2), the type and amount of the component (B) used in the adhesive composition and the curing catalyst. It is preferable to cure at about 70 to 150 ° C. for about 1 to 5 minutes and at the second stage (150 to 210 ° C.) for about 10 minutes to 3 hours.

In the present invention, the storage elastic modulus (E ′) at 150 ° C. of the polyimide film (1) is 2 to 10 GPa, and the storage elastic modulus (E ′) at 150 ° C. of the cured epoxy adhesive film layer (2) is By setting the value of the storage elastic modulus of the epoxy adhesive cured film layer (2) to 2.0 MPa to 0.2 GPa sufficiently smaller than that of the polyimide (1), the low thermal expansion property of the adhesive sheet can be realized. When the storage elastic modulus (E ′) at 150 ° C. of the epoxy adhesive cured film layer (2) exceeds 0.2 GPa, the low thermal expansion of the adhesive sheet cannot be realized, and if it is smaller than 2.0 MPa, Sufficient heat resistance cannot be obtained. The cured film usually has a dielectric constant of 3 to 4 at a frequency of 1 MHz and a linear expansion coefficient of 80 to 300 ppm / ° C.

  The adhesive sheet of the present invention is composed of two layers of a polyimide film (1) and an epoxy adhesive cured film layer (2). A method for producing such an adhesive sheet is obtained by applying the adhesive composition on a polyimide film (1) and semi-curing at about 70 to 150 ° C. The film thickness of the polyimide film (1) is not particularly limited, and may be appropriately determined in consideration of the voltage applied when the adhesive sheet is used as a circuit board, the insulation properties and the mechanical strength of the polyimide film (1). However, considering the ease of making the polyimide film (1) and the workability during the production of the multilayer printed board, the film thickness of the polyimide film (1) is usually preferably about 5 to 40 μm. The thickness of the epoxy adhesive cured film layer (2) is not particularly limited as long as it is larger than the thickness of the conductive layer forming the circuit, but the polyimide film (1) and the epoxy adhesive cured film layer (2 ) Is preferably adjusted to 1: 0.5 to 3 because a sufficient thickness of the conductive layer and low thermal expansion of the adhesive sheet are exhibited.

In the adhesive sheet of the present invention, the polyimide film (1) is a polyimide film having a storage elastic modulus of 2 to 10 GPa and a thermal expansion coefficient of 0 to 6 ppm, and an elastic modulus at 150 ° C. of the cured epoxy adhesive film layer (2). Needs to satisfy 2.0 MPa to 0.2 GPa. When the storage elastic modulus (E ′) at 150 ° C. of the epoxy adhesive cured film layer (2) exceeds 0.2 GPa, the low thermal expansion property of the adhesive sheet cannot be realized, and when it is smaller than 2.0 MPa, Sufficient heat resistance cannot be obtained. In order to reduce the thermal expansion of the multilayer printed circuit board formed by laminating the adhesive sheet of the present invention, it is effective to mainly control the thermal expansion coefficient of the adhesive sheet used for lamination to the polyimide film. A polyimide film having an expansion coefficient is used to increase the difference in elastic modulus between the polyimide film (1) and the cured epoxy adhesive film layer (2).

  The thermal expansion property of the adhesive film of the present invention is such that two layers of the adhesive sheet prepared by the above method are laminated so that the polyimide film (1) and the cured epoxy adhesive film layer (2) are alternate, and finally bonded. Laminate the same polyimide film (1) used for the production of the sheet, heat press at 140 ° C. for 1 minute and pressure of 8 MPa, and then completely cure the epoxy adhesive cured film layer (2) in an oven. It evaluates by measuring the thermal expansion coefficient of the laminated film (structure (1) / (2) / (1) / (2) / (1)) which can be performed. In the present invention, the composition of the polyimide film (1), each component constituting the adhesive composition, each of the polyimide film (1) and the cured epoxy adhesive film layer (2) so that the above value is 10 ppm or less. The film thickness is appropriately determined.

  A method for producing the multilayer printed board of the present invention is obtained by laminating the adhesive sheet of the present invention on a core material, and examples thereof include a method described in JP-A-2008-277384.

A core material (inner layer substrate) having a circuit pattern on both sides formed by a subtractive method or a semi-additive method is used. In the subtractive method, a CCL in which a glass fiber or an aramid fiber is impregnated with an epoxy resin is laminated with a copper foil or a polyimide film (1) used in the present invention is laminated with a copper foil, Japanese Patent Application Laid-Open No. 2003-136632 The double-sided CCL formed by wet-plating a block copolymerization type polyimide-silica hybrid by the method described in the publication No., or by performing electrolytic plating after forming a seed layer on the polyimide film (1) by sputtering. It is done. As a semi-additive method, glass fiber or aramid fiber is impregnated with epoxy resin and cured, or polyimide film (1) is wet electroless plated or sputtered to form a seed layer, and then patterned with a resist film. After performing the above, a core material that can be formed by processes such as electrolytic copper plating, removing the resist, and etching the seed layer can be mentioned. Among such core materials, those prepared by a semi-additive method are preferable because the fine pitch is easy.

The core material patterned by the above method is pasted with the adhesive sheet having the cured epoxy adhesive layer (2) of the semi-cured state of the present invention, punched in the adhesive sheet for a build-up type multilayer substrate, and then in the hole and the build-up type multilayer substrate A build-up layer is formed by forming a circuit on the surface of the polyimide film (1) of the adhesive sheet for use. More specifically, after laminating the above-mentioned adhesive sheet on the surface of the inner layer substrate on which the circuit pattern is formed, it is integrated by heating press and the epoxy adhesive cured film layer (2) is completely cured. Thereafter, via holes for signal transmission for connecting a plurality of circuit patterns are formed on the bonded adhesive sheet. Patterning of the polyimide film (1) on the surface of the adhesive sheet is performed by a semi-additive method in the same manner as described above using a seed layer formed by sputtering or wet electroless plating. At this time, since the adhesion of sputtering or wet electroless plating is excellent, it is preferable to use a block copolymerized polyimide-silica hybrid film as the polyimide (1). Further, since the plating of the via hole can be performed simultaneously with the plating of the surface of the polyimide film (1), it is preferable to use wet electroless plating as a seed layer forming method. The build-up layer may be formed only on one side of the laminated board on which a circuit pattern is formed as necessary.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In each example, parts and% are based on weight unless otherwise specified.

(Preparation of adhesive composition)
Each component was mixed and dissolved at the blending ratio shown in Table 1 to prepare an epoxy resin composition.

表中、ビフェニル型エポキシ樹脂は、商品名：ＹＸ−４０００（ジャパンエポキシレジン（株）製）、ノボラック型エポキシ樹脂は、商品名：ＹＤＰＮ−６３８（東都化成（株）製）、ビスフェノールＡ型エポキシ樹脂は、商品名：ＹＤ０１４（東都化成（株）製）、フォスファゼン誘導体は、商品名：ＳＰＨ−１００（大塚化学（株）製）、フェノールノボラック樹脂は、商品名：タマノル７５９（荒川化学工業（株）製）、カルボキシＮＢＲは、商品名：ＸＥＲ−３２Ｃ（ＪＳＲ（株）製）、水酸化アルミニウムは、商品名：ハイジライトＨ−４２Ｍ（昭和電工（株）製）、２−エチル−４−メチルイミダゾールは、商品名：２Ｅ４ＭＺ（四国化成（株）製）を表す。

In the table, biphenyl type epoxy resin is trade name: YX-4000 (manufactured by Japan Epoxy Resin Co., Ltd.), and novolak type epoxy resin is trade name: YDPN-638 (made by Toto Kasei Co., Ltd.), bisphenol A type epoxy. The resin is trade name: YD014 (manufactured by Toto Kasei Co., Ltd.), the phosphazene derivative is trade name: SPH-100 (manufactured by Otsuka Chemical Co., Ltd.), and the phenol novolac resin is trade name: Tamanoru 759 (Arakawa Chemical Industries ( Co., Ltd.), Carboxy NBR is trade name: XER-32C (manufactured by JSR Corporation), Aluminum hydroxide is trade name: Heidilite H-42M (made by Showa Denko KK), 2-ethyl-4 -Methylimidazole represents a brand name: 2E4MZ (manufactured by Shikoku Kasei Co., Ltd.).

Example 1 (Production of adhesive sheet having a semi-cured epoxy adhesive layer (2))
Block copolymerized polyimide-silica hybrid film (trade name Pomilan T25, manufactured by Arakawa Chemical Industries, Ltd.) mol% of p-phenylenediamine in diamine component = 80%, thermal expansion coefficient = 4 ppm, storage elastic modulus = 9.3 GPa, membrane Adhesive composition A described in Table 1 was applied on a thickness of 25 μm and dried at 140 ° C. for 3 minutes to prepare an adhesive sheet having a cured film thickness of 25 μm. Storage elastic modulus of cured epoxy adhesive layer at 150 ° C. = 0.05 GPa, film thickness ratio = 1: 1.

Example 2 (Production of adhesive sheet having a semi-cured epoxy adhesive layer (2))
Block copolymerized polyimide-silica hybrid film (trade name Pomilan T25, manufactured by Arakawa Chemical Industries, Ltd.) mol% of p-phenylenediamine in diamine component = 80%, thermal expansion coefficient = 4 ppm, storage elastic modulus = 9.3 GPa, membrane Adhesive composition B described in Table 1 was applied on a thickness of 25 μm and dried at 140 ° C. for 3 minutes to prepare an adhesive sheet having a cured film thickness of 75 μm. Storage elastic modulus at 150 ° C. of the cured epoxy adhesive layer = 0.02 GPa, film thickness ratio = 1: 3.

Example 3 (Production of adhesive sheet having a semi-cured epoxy adhesive layer (2))
Block copolymerized polyimide-silica hybrid film (trade name Pomilan T12, manufactured by Arakawa Chemical Industries, Ltd.) mol% of p-phenylenediamine in diamine component = 80%, thermal expansion coefficient = 6 ppm, storage elastic modulus = 9.1 GPa, membrane Adhesive composition C described in Table 1 was applied onto a thickness of 12 μm and dried at 140 ° C. for 3 minutes to prepare an adhesive sheet having a cured film thickness of 12.5 μm. Storage elastic modulus of cured epoxy adhesive layer at 150 ° C. = 0.2 GPa, film thickness ratio = 1: 0.5.

Comparative Example 1 (Manufacture of an adhesive sheet having a semi-cured epoxy adhesive layer (2))
Adhesive composition on commercially available polyimide film (trade name Kapton H, manufactured by Toray DuPont Film, mol% of p-phenylenediamine in diamine component = 0%, thermal expansion coefficient = 43 ppm, elastic modulus = 3.5 GPa, film thickness 25 μm) The product A was applied and dried to prepare an adhesive sheet having a cured film thickness of 50 μm.

Comparative Example 2 (Production of adhesive sheet having a semi-cured epoxy adhesive layer (2))
Block copolymerized polyimide-silica hybrid film (trade name Pomilan T25, manufactured by Arakawa Chemical Industries, Ltd.) mol% of p-phenylenediamine in diamine component = 80%, thermal expansion coefficient = 4 ppm, storage elastic modulus = 9.3 GPa, membrane Adhesive composition D described in Table 1 was applied on a thickness of 25 μm and dried at 140 ° C. for 3 minutes to prepare an adhesive sheet having a cured film thickness of 75 μm. Storage elastic modulus at 150 ° C. of cured epoxy adhesive layer = 8.0 GPa, film thickness ratio = 1: 3.

Comparative Example 3 (Manufacture of an adhesive sheet having a semi-cured epoxy adhesive layer (2))
Block copolymerized polyimide-silica hybrid film (trade name Pomilan T25, manufactured by Arakawa Chemical Industries, Ltd.) mol% of p-phenylenediamine in diamine component = 80%, thermal expansion coefficient = 4 ppm, storage elastic modulus = 9.3 GPa, membrane Adhesive composition E described in Table 1 was applied onto a thickness of 25 μm and dried at 140 ° C. for 3 minutes to prepare an adhesive sheet having a cured film thickness of 75 μm. Storage elastic modulus of cured epoxy adhesive layer at 150 ° C. = 1.0 MPa, film thickness ratio = 1: 0.5.

(Thermal expansion)
Two adhesive sheets were stacked on the polyimide film used in the preparation of the adhesive sheets of Examples and Comparative Examples, and after pressure-pressing at 8 MPa, 140 ° C. for 1 minute, cured at 180 ° C. for 3 hours. A laminate comprising 5 layers of polyimide film / adhesive composition layer / polyimide film / adhesive composition layer / polyimide film was obtained. The thermal expansion property of the obtained laminate was measured using a thermomechanical analyzer (tensile mode of chuck distance 20 mm, specimen width 4 mm, load 10 mg, heating rate: 10 ° C./min), 100 ° C. The thermal expansion coefficient at ˜200 ° C. was evaluated. The measurement results are shown in Table 2.

From Table 2, it is clear that the laminates obtained by the examples are excellent in low thermal expansion.

(Adhesiveness)
On electrolytic copper foil with a thickness of 18 μm ("F2-WS" manufactured by Furukawa Circuit Foil Co., Ltd. (18
After the above film with resin is superposed on 1 μm)), it is heated and pressed at 1 MPa, 140 ° C. for 1 minute, then cured at 180 ° C. for 3 hours, and a cured adhesive is obtained between the polyimide film and the copper foil. A laminate having layers was produced. The peel strength between the copper foil and the film was measured for the laminates of Examples and Comparative Examples according to JIS C-6481. Table 3 shows the measurement results.

From Table 3, it is clear that the laminates obtained by the examples are excellent in adhesiveness.

(Heat-resistant)
The sample laminated and integrated with the copper foil used for measuring the adhesiveness was cut into 25 mm × 25 mm and floated in a 260 ° C. solder bath for 180 seconds. The case where there was an abnormality such as swelling and peeling after 180 seconds was rated as x, and the case where there was no abnormality was marked as ◯. Table 4 shows the measurement results.

From Table 4, it is clear that the laminates obtained by the examples are excellent in heat resistance unlike the comparative examples.

(Flame retardance)
The adhesive sheets of Examples and Comparative Examples were cured at 180 ° C. for 3 hours. The cured adhesive sheet was tested based on the UL standard (UL94 VTM) test. In the case where the reference condition satisfies VTM-0, it was evaluated as ◯, and in the case where it was not satisfied, it was evaluated as x. Table 5 shows the measurement results.

From Table 5, it is clear that the laminates obtained by the examples are excellent in flame retardancy unlike the comparative examples.

Example 4 (Manufacture of multilayer printed circuit board)

The above-mentioned semi-cured epoxy adhesive cured film layer (2) is formed on the surface of the inner substrate on which the circuit pattern is formed by wet plating the block copolymerization type polyimide-silica hybrid by the method described in JP-A-2003-136632. After the adhesive sheets having the above were stacked, they were integrated by a heating press, and the epoxy adhesive cured film layer (2) was completely cured. Thereafter, via holes for signal transmission for connecting a plurality of circuit patterns to the bonded adhesive sheet were formed by a UV-YAG laser. Patterning of the polyimide film (1) on the surface of the adhesive sheet was performed by a semi-additive method using a seed layer formed by a wet electroless plating method. By repeating the above steps, a multilayer printed circuit board could be produced.

As is apparent from Tables 2 to 5, it is clear that the laminate according to the present invention is excellent in adhesion and heat resistance, and is optimal for the production of multilayer printed wiring boards as well as ordinary printed wiring boards. is there.

Claims (6)

An epoxy resin adhesive having a storage elastic modulus at 150 ° C. of 2.0 MPa to 0.2 GPa on a polyimide film (1) having a storage elastic modulus of 2 to 10 GPa at 150 ° C. and a thermal expansion coefficient of 0 to 6 ppm. A cured film layer (2) is provided;
The polyimide film (1) is a block copolymerized polyimide-silica hybrid film obtained by thermosetting the alkoxy group-containing silane-modified block copolymer polyamic acid (b),
The polyamic acid obtained by reacting the alkoxy group-containing silane-modified block copolymer polyamic acid (b) with a polyamic acid obtained by reacting a tetracarboxylic dianhydride and a diamine with an epoxy group-containing alkoxysilane partial condensate (A) is obtained separately by mixing and condensing polyamic acid obtained by reacting tetracarboxylic dianhydride and diamine.
The use ratio of the polyamic acid and the epoxy group-containing alkoxysilane partial condensate is the equivalent of the epoxy group of the epoxy group-containing alkoxysilane partial condensate / the number of moles of tetracarboxylic dianhydride used for the polyamic acid is 0.01 to 0.6,
The epoxy group-containing alkoxysilane partial condensate is obtained by dealcoholizing an epoxy compound having one hydroxyl group in one molecule and an alkoxysilane partial condensate,
The alkoxysilane partial condensate uses 70% by weight or more of tetramethoxysilane partial condensate or methyltrimethoxysilane partial condensate in the total amount of alkoxysilane partial condensate, and has a number average molecular weight of 230 to 2000, The average number of Si in one molecule is 2-11,
The segment of polyamic acid (a) has an alkoxysilane partial condensate in the side chain, forms silica by a sol-gel reaction, and is obtained separately by reacting tetracarboxylic dianhydride and diamines. Has no silica,
The adhesive sheet having a thermal expansion coefficient of 10 ppm or less, wherein 80 to 100 mol% of the diamine constituting the alkoxy group-containing silane-modified block copolymeric polyamic acid (b) is p-phenylenediamine . An epoxy resin adhesive cured film layer (2) obtained by curing an adhesive composition containing an epoxy resin (A), an epoxy curing agent (B), an elastomer (C) and a flame retardant (D) The adhesive sheet according to claim 1. The adhesive sheet according to claim 2, wherein the adhesive composition contains 5 to 50% by weight of the elastomer (C) as a solid content. The adhesive sheet according to any one of claims 1 to 3 , which does not contain a halogen and is flame retardant VTM-0. The adhesive sheet according to any one of claims 1 to 4 , wherein the film thickness ratio of the polyimide film (1) and the cured epoxy adhesive film layer (2) is 1: 0.5-3. Multilayer printed board to the adhesive sheet according to any one of claims 1-5, obtained by an electroless plating process.