JP2003133704A - Circuit board and bonding sheet for coverlay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board using a bonding sheet for coverlay that maintains the original electrical insulating properties in the conventional coverlay film, at the same time, does not have a heat-resistant film as a support base, and can thin an entire film thickness as much as possible, and to provide the bonding sheet for coverlay. SOLUTION: In the circuit board, wiring is covered with the bonding sheet for coverlay that has a thickness of 3 to 100 μm and does not have any coverlay films. In the bonding sheet for coverlay used for the circuit board, a peeling film is laminated on both the surfaces of an adhesive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board whose wiring is covered by a cover layer composed of only an adhesive layer, and an adhesive sheet for a cover layer used for the circuit board.

[0002]

2. Description of the Related Art A cover ray film with an epoxy adhesive which has been conventionally used is a heat resistant film such as a polyimide film in order to prevent warpage after being bonded to a circuit board and to improve electric insulation. Were stacked. Therefore, it is difficult to reduce the total film thickness because of the two-layer structure of the adhesive layer and the heat resistant film, and the difference in the coefficient of linear expansion between the heat resistant film and the copper forming the wiring is large. When a high-rigidity film is used to reduce the linear expansion coefficient of the heat-resistant film, it is difficult to bend the circuit board compactly.

When a coating material coating solution used for a part is used for a cover ray, the taper angle of the coating film end portion of the wiring terminal portion is often large, and gold plating is often used. At this time, the tin plating solution penetrates deeply at the ends, and the electrical insulation, which is the purpose of providing the cover layer made of the coating material, fails.

[0004]

DISCLOSURE OF THE INVENTION The object of the present invention is to maintain the original electrical insulation of the conventional cover-ray film and not to have a heat-resistant film as a supporting substrate, and to provide the entire film thickness. An object of the present invention is to provide a circuit board using a cover sheet adhesive sheet that can be thinned to a minimum, and a cover sheet adhesive sheet.

[0005]

The present invention has a thickness of 3 μm.
The present invention relates to a circuit board in which the wiring is covered by an adhesive sheet for a cover ray having a cover film thickness of m to 100 μm. The present invention also relates to an adhesive sheet for a coverlay, which is used for the above-mentioned circuit board and has a release film laminated on both sides of an adhesive.

[0006]

Preferred embodiments of the present invention will be listed below. 1) The above-mentioned circuit board in which the adhesive sheet for covering is composed of a polyimide siloxane having a group reactive with an epoxy group, a small amount of an epoxy resin, and imidazoles. 2) The circuit board as described above, wherein the cover sheet adhesive sheet is covered with a flexible printed wiring board by heat-pressing after punching and cutting. 3) The above-mentioned circuit board in which the wiring is obtained from a polyimide-copper laminate of all-polyimide in which a polyimide layer and a copper layer are laminated by a laminating method, a casting method or a metal deposition method-copper plating method. .

4) The above-mentioned circuit board in which the wiring is copper-plated on a through-hole formed by laser processing or chemical etching on the polyimide layer of the polyimide-copper laminate and further metal-plated. . 5) The above-mentioned circuit board in which the cover sheet adhesive sheet is covered with a flexible printed wiring board by heat-pressing after perforating and cutting. 6) The cover sheet adhesive sheet as described above, wherein the adhesive contains a black pigment for light shielding. 7) The adhesive sheet for cover lei, wherein the peelable film is a peel-treated polyester film.

The cover sheet adhesive cover of the present invention comprises, for example, an adhesive layer containing a flexible thermosetting resin as a main component and having a latent thermosetting function. In the present invention, the cover sheet adhesive sheet comprising this adhesive layer has a peelable film laminated on both sides thereof, and for example, it is peeled off before being overlapped with the wiring and is then heat-pressed after being laminated with the wiring. By thermosetting and laminating and integrating them, a circuit board having good insulating properties can be obtained without using a cover film.

In the present invention, the thickness is 3 μm to 10 μm.
It is necessary to use a cover ray adhesive sheet having a cover film thickness of 0 .mu.m, which allows a compact bending without curling the circuit board. The thickness of the cover sheet adhesive cover is 3 μm.
If it is smaller than 100 μm, the wiring will not be embedded sufficiently.
Even if it is larger, it is not preferable because it has no effect and rather reduces flexibility. Further, in the case where the cover film is laminated, a curl occurs in the circuit board when the difference in the linear expansion coefficient between the polyimide film normally used for the cover film and the copper forming the wiring is large, If a highly rigid film is used to reduce the linear expansion coefficient of the polyimide film, it is difficult to bend the circuit board compactly.

The adhesive in the present invention includes, but is not limited to, a combination of a flexible thermosetting resin such as polyimide siloxane, a small amount of epoxy resin and a latent curing agent. For example, a combination of a polybutadiene polyol, a polyester such as a polyester polyol, a polybutadiene polyblock isocyanate, a small amount of rubber fine particles and a small amount of polyamide fine particles may be mentioned.

The above-mentioned polyimide siloxane is a tetracarboxylic acid composed of a diaminopolysiloxane, a diamine component composed of an aromatic diamine having a plurality of benzene rings and an aromatic diamine having a polar group, and a tetracarboxylic acid capable of providing a heat resistant polyimide. It can be obtained by polymerizing and imidizing the components. The diamine component is 40 to 90 mol% of diaminopolysiloxane and 5 to 30 mol% of aromatic diamine having a plurality of benzene rings.
And 5 to 30 mol% of an aromatic diamine having a polar group.

The above diaminopolysiloxane is
Formula _{(1) H 2 N-R} 1 - [Si (R 2) 2 -O-] n1 -Si (R 2) 2 -R 1 -NH 2 (1) ( where, R ₁ in the formula is 2 A valent hydrocarbon group or a phenyl group, R ₂ independently represents an alkyl group having 1 to 3 carbon atoms or a phenyl group, and n1 represents an integer of 3 to 30). Examples of suitable compounds of the above diaminopolysiloxane include α, ω-bis (2-aminoethyl) polydimethylsiloxane and α, ω-bis (3-
Aminopropyl) polydimethylsiloxane.

The aromatic diamine having a plurality of benzene rings is represented by the general formula (2) H ₂ N- [BzX] _n2 Y [XBz] _n2- NH ₂ (2) (wherein Bz in the formula is a benzene ring). X and Y each independently represent a direct bond, Bz, CH ₂ , C (CH ₃ ) ₂ , O or SO _2, and n 2 is 1 or 2). Specific preferred examples of the aromatic diamine having a plurality of benzene rings include 2,2-bis [4- (4-aminophenoxy) phenyl] propane.
(BAPP) may be mentioned.

Further, the aromatic diamines having a polar group, the general formula _{(3) H 2 N-Bz} (r 1) n3 Y [XBz (r 1) n3] n4 -NH 2 (3) ( where formula Where Bz represents a benzene ring, X and Y independently represent a direct bond, CH ₂ , C (CH ₃ ) ₂ , O, Bz or SO ₂ , r 1 represents COOH, n 3 is 1, and
n4 is 0 or 1. ) Are preferable.
Specific preferred examples of the aromatic diamine having a polar group include 3,5-diaminobenzoic acid and bis (3-carboxy, 4-aminophenyl) methane.

As the tetracarboxylic acid component capable of giving the above heat resistant polyimide, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'-
Biphenyl tetracarboxylic dianhydride, 3,3 ', 4
Examples thereof include aromatic tetracarboxylic dianhydrides such as 4′-benzophenone tetracarboxylic dianhydride and bis (3,4-dicarboxyphenyl) ether dianhydride anhydrous.

The above-mentioned polyimide siloxane is preferably prepared by polymerizing each component in a reaction vessel equipped with a stirrer in an organic solvent under the flow of humidified nitrogen to form a polyamic acid, which is further imidized or made into a polyamic acid. It can be obtained by producing a polyimide polymer by omitting steps and performing imidization in a single step at a relatively high temperature. The polymerization reaction of the tetracarboxylic acid component capable of giving the heat-resistant polyimide and the diamine is random, block, or a mixture after homo-reaction of two or more kinds (in some cases, further recombination reaction)
Any of the above may be used. The polyimide polymer, which is the above-mentioned polyimide siloxane, can be used as it is without being isolated from the solution.

In the organic solvent of each component, the reaction ratio of each component is such that the tetracarboxylic acid component is approximately equivalent to the total amount of diamine, preferably 0.95 to tetracarboxylic acid component per mol of diamine. It can be obtained by reacting in a molar ratio of about 1.2 mol. Also, as the polyimide siloxane, those called from oligomers from high molecular weight can be used, but the logarithmic viscosity (0.5
g / 100 ml) is preferably 0.16 to 3.

As the organic solvent in the above reaction, a nitrogen-containing solvent such as N, N-dimethylacetamide,
N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, N-methyl-2-pyrrolidone, ether solvents such as diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether Organic polar solvents such as ter (triglyme), tetraglyme, dioxane, tetrahydrofuran and γ-butyrolactone can be mentioned.

As the above-mentioned epoxy resin, a polyfunctional epoxy resin which is a glycidyl ether compound of a polyphenol compound, a polyfunctional epoxy resin which is a glycidyl ether of various novolak resins, an alicyclic epoxy resin, an aliphatic resin Examples thereof include epoxy resins, heterocyclic epoxy resins, glycidyl ester epoxy resins, glycidyl amine epoxy resins, and epoxy resins obtained by glycidylating halogenated phenols. Here, the polyfunctional epoxy resin is an epoxy resin having two or more glycidyl groups.

Glycidyl ether, a polyphenol compound
Examples of the polyfunctional epoxy resin that is a telluride include bisphenol A, bisphenol F, bisphenol S, 4,4'-biphenylphenol, tetramethylbisphenol A, and dimethylbisphenol. A, tetramethylbisphenol F, dimethylbisphenol F, tetramethylbisphenol S, dimethylbisphenol S, tetramethyl-4,4'-biphenol, dimethyl-4,4 ' -Biphenylphenol, 1- (4-hydroxyphenyl) -2- [4- (1,1-bis- (4-hydroxyphenyl) ethyl) phenyl] propane, 2,
2'-methylene-bis (4-methyl-6-tert-butylphenol), 4,4'-butylidene-bis (3-
Methyl-6-tert-butylphenol), trishydroxyphenylmethane, resorcinol, hydroquinone, pyrogallol, phenols having a diisopropylidene skeleton, 1,1-di-4-hydroxyphenylfluorene, etc. Examples thereof include polyfunctional epoxy resins which are glycidyl ether compounds of polyphenol compounds such as phenols having a fluorene skeleton and phenolated polybutadiene.

Examples of polyfunctional epoxy resins which are glycidyl ether compounds of various novolac resins include phenol, cresols, ethylphenols, butylphenols, octylphenols, and bisphenol A. ,
Novolak resins starting from various phenols such as bisphenol F, bisphenol S, and naphthols, phenol novolak resins containing xylylene skeleton, phenol novolac resins containing dicyclopentadiene skeleton, and phenol containing biphenyl skeleton. Examples thereof include glycidyl ether compounds of various novolac resins such as a lunovolac resin, a fluorene skeleton-containing phenol novolac resin, and a furan skeleton-containing phenol novolac resin.

Examples of the alicyclic epoxy resin include alicyclic epoxy resins having an aliphatic skeleton such as cyclohexane, and examples of the aliphatic epoxy resin include 1,4-butanediol and 1,6- Hexanediol,
Examples thereof include polyhydric alcohol glycidyl ethers such as polyethylene glycol and pentaerythritol.

Examples of the heterocyclic epoxy resin include heterocyclic epoxy resins having a heterocycle such as isocyanuric ring and hydantoin ring. Examples of the glycidyl ester-based epoxy resin include hexahydrophthalic acid diglycidyl ester. Examples of the epoxy resin include carboxylic acids, and examples of the glycidylamine-based epoxy resin include epoxy resins obtained by glycidylating amines such as aniline and toluidine.

Examples of epoxy resins obtained by glycidylating halogenated phenols include brominated bisphenols.
And halogenated phenols such as brominated bisphenol F, brominated bisphenol S, brominated phenol novolac, brominated cresol novolac, chlorinated bisphenol S and chlorinated bisphenol A. An epoxy resin obtained by glycidylating is mentioned.

Among these epoxy resins, which epoxy resin is used is appropriately selected according to the required characteristics, but a glycidyl ether type epoxy resin is preferable,
More preferably, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, a novolak type epoxy resin having a phenol skeleton and a naphthol skeleton, It is a novolac type epoxy resin having a phenol skeleton and a biphenyl skeleton, a novolac type epoxy resin having a triphenylmethane skeleton, and a novolac type epoxy resin having a dicyclopentadiene skeleton. The novolac type epoxy resin having a phenol skeleton and a naphthol skeleton more preferably has a methyl group in the phenol skeleton. These epoxy resins can be used as one kind or a mixture of two or more kinds according to need such as imparting heat resistance and flame retardancy.

Commercially available products are, for example, Bisphenol A type or Bisphenol F type epoxy resin, trade name: Epicort 807, 8 manufactured by Yuka Shell Epoxy Co., Ltd.
28,828 EL, polyfunctional epoxy resin such as Sumitomo Chemical Co., Ltd., ELM-100, and glycidyl amine epoxy resin such as Mitsubishi Gas Chemical Co., Inc., trade name: Tetrad X, phenol skeleton. As the novolac type epoxy resin having a naphthol skeleton, for example, NC-7000 (trade name: manufactured by Nippon Kayaku Co., Ltd.), NC-7300 (trade name: manufactured by Nippon Kayaku Co., Ltd.), a phenol skeleton and a biphenyl skeleton are used. The novolac type epoxy resin has NC-3000P (trade name: manufactured by Nippon Kayaku Co., Ltd.), and the novolac type epoxy resin having a triphenylmethane skeleton is EPPN-501H, EPPN-502H.
(Trade name: manufactured by Nippon Kayaku Co., Ltd.), a novolac type epoxy resin having a dicyclopentadiene skeleton is XD-1000.
(Trade name: manufactured by Nippon Kayaku Co., Ltd.). It is particularly preferable that the epoxy resin has a melting point of 90 ° C. or lower, particularly about 0 to 80 ° C., or is a liquid at a temperature of 30 ° C. or lower.

Examples of the latent curing agent include acid anhydrides, phenols, imidazoles, dihydrazines, Lewis acids, Bronsted acid salts, polymercaptons, isocyanates, and blocks. Examples thereof include isocyanates, and imidazoles are particularly preferable. This latent curing agent means that it does not cure when dried for solvent removal. The curing agent may be appropriately used together with a known curing accelerator.

Examples of the above-mentioned acid anhydrides include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic acid anhydride, ethylene glycol anhydride trimellitic acid anhydride and biphenyltetracarboxylic acid. Aromatic carboxylic acid anhydride such as acid anhydride, aliphatic carboxylic acid anhydride such as azelaic acid, sebacic acid, dodecanedioic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, nadic acid anhydride, het Examples thereof include alicyclic carboxylic acid anhydrides such as acid anhydrides and hymic acid anhydrides.

Examples of the above-mentioned phenols include bisphenol A, bisphenol F, bisphenol S,
4,4'-biphenylphenol, tetramethylbisphenol A, dimethylbisphenol A, tetramethylbisphenol F, dimethylbisphenol F, tetramethylbisphenol S, dimethylbisphenol Phenolic S,
Tetramethyl-4,4'-biphenol, dimethyl-
4,4'-biphenylphenol, 1- (4-hydroxyphenyl) -2- [4- (1,1-bis- (4-hydroxyphenyl) ethyl) phenyl] propane, 2,
2'-methylene-bis (4-methyl-6-tert-butylphenol), 4,4'-butylidene-bis (3-
Methyl-6-tert-butylphenol), trishydroxyphenylmethane, resorcinol, hydroquinone, pyrogallol, phenols having a diisopropylidene skeleton, 1,1-di-4-hydroxyphenylfluorene, etc. A phenol having a fluorene skeleton, a phenolated polybutadiene, a phenol, a cresol, an ethylphenol, a butylphenol, an octylphenol, a bisphenol A, a bisphenol F, Various phenols such as bisphenol S and naphthols
-Based novolak resin, xylylene skeleton-containing phenol novolak resin, dicyclopentadiene skeleton-containing phenol novolak resin, biphenyl skeleton-containing phenol novolak resin, fluorene skeleton-containing phenol novolak resin, furan skeleton-containing phenol novolac resin, etc. Various novolak resins, brominated bisphenol A, brominated bisphenol F, brominated bisphenol
And halogenated phenols such as brominated phenol novolac, brominated cresol novolac, chlorinated bisphenol S and chlorinated bisphenol A.

Examples of the above-mentioned imidazoles include 2
-Ethyl-4-methylimidazole (sometimes abbreviated as 2E4MZ), 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2
-Heptadecyl imidazole, 2-phenyl-4-methyl imidazole, 1-benzyl-2-phenyl imidazole, 1-benzyl-2-methyl imidazole, 1-cyanoethyl-2-methyl imidazole , 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2
-Undecyl imidazole, 2,4-diamino-6
(2′-Methylimidazole (1 ′)) ethyl-s-triazine, 2,4-diamino-6 (2′-undecylimidazole (1 ′)) ethyl-s-triazine, 2,4
-Diamino-6 (2'-ethyl, 4-methylimidazo-
(1 ′)) ethyl-s-triazine, 2,4-diamino-6 (2′-methylimidazole (1 ′)) ethyl-
s-Triazine / isocyanuric acid adduct, 2-methylimidazole isocyanuric acid 2: 3 adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-
3,5-dihydroxymethylimidazole, 2-phenyl-4-hydroxymethyl-5-methylimidazole,
Various imidazoles of 1-cyanoethyl-2-phenyl-3,5-dicyanoethoxymethylimidazole, and those imidazoles and phthalic acid, isophthalic acid,
Examples thereof include salts with polyvalent carboxylic acids such as terephthalic acid, trimellitic acid, pyromellitic acid, naphthalenedicarboxylic acid, maleic acid and oxalic acid.

The proportion of each of the above components is 1 to 50 parts by weight, especially 5 to 50 parts by weight of epoxy resin to 100 parts by weight of polyimide siloxane, and a latent curing agent to 100 parts by weight of epoxy resin, It is preferable that the amount of imidazole is 0.01 to 10 parts by weight. 3 of the above
In addition to the components, inorganic fillers such as talc, mica, barium sulphate, powdered silica (functioning as a defoamer).
1 to 25 with respect to 100 parts by weight of polyimide siloxane
It is preferable to add parts by weight (total amount). Further, a black pigment for shading may be blended.

The adhesive in the present invention is, for example, an adhesive solution obtained by dissolving polyimide siloxane, an epoxy resin and a latent curing agent, preferably imidazoles in the above organic solvent, or an organic solvent of polyimide siloxane. The adhesive solution obtained by adding other components to the solution is applied to a peelable film to a thickness of about 10 to 300 μm, and dried by heating to form a dry coating film having a thickness of 3 to 100 μm. The cover sheet adhesive sheet of the present invention can be obtained by further laminating a peelable film on the adhesive surface laminated on the peelable film. Examples of the releasable film include polyester films and poly-4-methylpentene-1 films, and preferably those obtained by subjecting at least one surface of a polyester film to a release treatment.

In the present invention, the metal wiring covered with the above-mentioned cover ray adhesive is a substrate, for example, a ceramic substrate, a glass fiber reinforced epoxy resin substrate, a flexible substrate, or the like, preferably a high heat resistant aromatic polyimide. Of a metal-polyimide laminate in which a polyimide film comprising a multilayer polyimide film comprising a polyimide layer containing as a main constituent material and a polyimide layer having a low glass transition temperature having thermocompression bonding property and / or flexibility and a metal layer are laminated. A wiring such as a metal wiring board provided with terminals by etching a metal layer to form a pattern can be used. In the case of a double-sided wiring substrate, a metal-polyimide laminate having metal layers on both sides is provided with a through hole penetrating the metal-insulating layer-metal layer, and the exposed insulating layer is provided with a metal layer by a chemical method. Adsorb, then electro copper plating to form electro copper plating layer,
After etching the metal on both surfaces, the sulfol portion and the terminal portion can be plated with gold to obtain a double-sided conduction type wiring board. The metal-polyimide laminate is preferably obtained by laminating method, casting method or metal vapor deposition method-copper plating method, polyimide of an all-polyimide in which a polyimide layer and a copper layer are laminated-
A copper laminated body is mentioned.

In particular, as the wiring, a high heat-resistant aromatic polyimide which preferably contains a biphenyltetracarboxylic acid component as an aromatic tetracarboxylic acid component and has a glass transition temperature of 300 ° C. or higher or whose glass transition temperature cannot be measured is mainly used. A polyimide film as a constituent material having a glass transition temperature of 200 on at least one surface of the polyimide film.
Having a low glass transition temperature polyimide resin layer having a thermocompression bonding property of ˜375 ° C. and / or flexibility, and the glass transition temperature of the low glass transition temperature polyimide resin is not higher than the glass transition temperature of the high heat-resistant aromatic polyimide. A wiring of a substrate obtained by patterning a metal layer of a metal layer laminate in which a metal layer is laminated on a certain polyimide film through the polyimide resin layer having the thermocompression bonding property and / or flexibility and further copper plating is performed. Can be mentioned.

The above polyimide film has, for example, heat resistance and thermocompression bonding property on one or both surfaces of a highly heat resistant aromatic polyimide precursor solution dried film containing a biphenyltetracarboxylic acid component as an aromatic tetracarboxylic acid component. After laminating a polyimide precursor solution having flexibility, or more preferably, coextrusion-thermocompression bonding with heat resistance on one side or both sides of the precursor solution of a highly heat-resistant aromatic polyimide by a casting film forming method. And / or a polyimide precursor solution having flexibility is laminated, then dried and imidized to obtain a multilayer polyimide film.

The above-mentioned highly heat-resistant aromatic polyimide is preferably para and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (hereinafter sometimes abbreviated as s-BPDA). -Phenylenediamine (hereinafter sometimes abbreviated as PPD) and optionally 4,4'-
It is produced from diaminodiphenyl ether (hereinafter sometimes simply referred to as DADE) and / or pyromellitic dianhydride (hereinafter sometimes simply referred to as PMDA). In this case, PPD / DADE (molar ratio) is 100/0 to 10/90, especially 100/0 to 85/15.
Is preferred. In addition, s-BPDA / PMDA
Is 100: 0 to 15/85, especially 100: 0 to 50/5
It is preferably 0.

The above-mentioned high heat resistant polyimide has a glass transition temperature of 30 in the case of a single layer polyimide film.
Those having a temperature of 0 ° C. or higher are preferable, and those which cannot be confirmed particularly at a temperature of lower than 350 ° C. are preferable, and particularly, the linear expansion coefficient (50 to 200 ° C.) (MD, TD and any of these averages) is 5 × 10 ^{−6 to} 25 × 10 ⁻⁶ cm / cm /
What is ° C is preferred. In the synthesis of this highly heat resistant polyimide, finally, if the ratio of each component is within the above range, random polymerization, block polymerization, blending or preliminarily synthesizing two or more kinds of polyimide precursor solutions is performed. It can be achieved by any method in which the solution is mixed and the copolymer is obtained by recombination of the respective polyimide precursors.

The resin layer having thermocompression bonding property and / or flexibility has Tg: glass transition temperature of 200 to
The thermocompression-bonding polyimide which is 275 degreeC can be mentioned. In particular, 1,3-bis (4-aminophenoxybenzene) (hereinafter sometimes abbreviated as TPER) and 2,
A thermocompression-bondable polyimide produced from 3,3 ′, 4′-biphenyltetracarboxylic dianhydride (hereinafter sometimes abbreviated as a-BPDA) is preferable. Alternatively, 4,4′-oxydiphthalic acid dianhydride (ODP
A) and pyromellitic dianhydride and 1,3-bis (4
-Aminophenoxybenzene). Furthermore, 1,3-bis (3
-Aminophenoxy) benzene and 3,3 ', 4,4'-
From benzophenone tetracarboxylic dianhydride, or from 3,3'-diaminobenzophenone and 1,3-
Bis (3-aminophenoxy) benzene and 3,3 ′,
Thermocompression-bondable polyimide produced from 4,4′-benzophenone tetracarboxylic acid dianhydride can be mentioned. Further, as the resin having thermocompression bonding property and / or flexibility in addition to the heat resistance, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether are used. Mention may be made of the flexible (and thus high elongation) polyimides produced.

A solution of the polyimide precursor having thermocompression bonding property and / or flexibility together with the heat resistance is applied to one side or both sides of the solution dried film of the above-mentioned highly heat resistant aromatic polyimide precursor and laminated, Alternatively, coextrusion-
Heat resistance as well as thermocompression bonding and / or
Alternatively, a multilayer polyimide film obtained by laminating a polyimide precursor solution having flexibility on one or both sides of a highly heat-resistant aromatic polyimide precursor solution, and then drying and imidizing is preferably plasma discharge treatment or the like. After the surface treatment, a metal layer can be directly formed to obtain a laminate.

For the purpose of limiting gelation of the above polyimide precursor, a phosphorus-based stabilizer such as triphenyl phosphite,
Triphenyl phosphate or the like can be added in the range of 0.01 to 1% with respect to the solid content (polymer) concentration during polyamic acid polymerization. For the purpose of promoting imidization,
A basic organic compound catalyst can be added to the solution. For example, imidazole, 2-imidazole, 1,2
-Dimethylimidazole, 2-phenylimidazole, etc. relative to polyamic acid (solid content) of 0.01 to 20
It can be used in proportions by weight, in particular 0.5 to 10% by weight. Since these form a polyimide film at a relatively low temperature, they are used in order to avoid insufficient imidization. Further, for the purpose of stabilizing the adhesive strength, an organic aluminum compound, an inorganic aluminum compound or an organic tin compound may be added to the aromatic polyimide raw material dope. For example, aluminum hydroxide, aluminum triacetylacetonate, etc. as aluminum or tin metal with respect to polyamic acid (solid content) of 1 ppm or more,
In particular, it can be added in a proportion of 1 to 1000 ppm.

The organic solvent used for producing the above-mentioned polyimide precursor is N-methyl-ether for both highly heat-resistant aromatic polyimide and thermocompression-bondable and / or flexible aromatic polyimide. 2-pyrrolidone, N,
N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, N-methylcaprolactam, cresols and the like can be mentioned, and these organic solvents can be used alone. Alternatively, two or more kinds may be used in combination.

In the production of the above-mentioned multilayer polyimide film, a coating-casting film-forming method, for example, a solution-dried film of a highly heat-resistant aromatic polyimide precursor having one side or both sides having a thermocompression-bonding and / or flexible fragrance is used. Group polyimide precursor solution coating or coextrusion-casting film forming method, for example, JP-A-3-180343 (Japanese Patent Publication No. 7-1026).
It can be carried out by supplying it to a two-layer or three-layer extrusion molding die by the coextrusion method described in JP-A No. 61) and casting it on a support. On one or both sides of the extrudate layer that gives a highly heat-resistant aromatic polyimide, a thermocompression-bonding and / or flexible aromatic polyimide precursor solution is applied and laminated to form a multilayer film-like product, and after drying, Heating to a temperature not lower than the glass transition temperature (Tg) of the thermocompression-bondable and / or flexible aromatic polyimide to cause deterioration, preferably 300 to 500 ° C (surface temperature measured by a surface thermometer). (Preferably 1 at this temperature
Drying and imidizing (by heating for ~ 60 minutes) to produce a multilayer polyimide film having a thermocompression-bonding and / or flexible aromatic polyimide on one or both sides of a highly heat-resistant (base layer) aromatic polyimide. You can

The high heat resistant (base layer) polyimide layer has a thickness of 5 to 50 μm, particularly about 5 to about 40 μm, and preferably about 5 to about 25 μm. 5 μm
If it is less than the above range, problems occur in the mechanical strength and dimensional stability of the multilayer polyimide film produced. On the other hand, if the thickness is more than 50 μm, it is disadvantageous for fine patterning. The thermocompression-bondable and / or flexible aromatic polyimide layer preferably has a thickness of about 0.03 to 10 μm. The thickness of the multilayer polyimide film is about 7 to about 50 μm.
Degree, especially about 7-40 μm, among which 7-25 μm
It is preferably about the same. If it is less than 7 μm, it is difficult to handle the produced film, and the thicker it is, the more disadvantageous it is for fine patterning. In particular, as a multilayer polyimide film, it has thermocompression-bonding and / or flexible polyimide layers on both sides, the total thickness is about 7 to 50 μm, and the tensile elastic modulus (25 ° C.) is 400 to 1000 kg.
It is preferably f / mm ² from the viewpoint of high density.

In the present invention, the metal layer of the metal layer laminate constituting the wiring is preferably a rolled copper foil, electrolytic copper foil,
Examples include vapor deposition and / or plated copper film. As the metal foil, the surface roughness is not so large and not so small, preferably Rz of the contact surface with polyimide is 3 μm or less, particularly 0.5 to 3 μm, and particularly 1.5 to 3 μm among them.
Those with m are preferred. Such metal foils, eg copper foils, are known as VLPs, LPs (or HTEs). The thickness of the metal foil is about 3 μm to 35 μm, especially 3 μm.
It is preferably about m to 12 μm, and particularly preferably about 3 to 9 μm. The larger the thickness of the metal foil, the more disadvantageous it is for fine patterning. When Rz is small, a metal foil surface-treated may be used.

The above-mentioned metal layer laminate is preferably a continuous laminator such as a roll laminate or a double belt press, in which the thermocompression-bonding multilayer polyimide film and the metal foil are thermocompression-bonded. Hot multi-layer polyimide film only or hot air supply so that it can be preheated at about 150 to 250 ° C, especially at a temperature higher than 150 ° C and below 250 ° C for about 2 to 120 seconds immediately before introducing the thermocompression-bonding multilayer polyimide film and metal foil. A laminate that is a flexible metal foil laminate can be obtained by preheating with a device or a preheater such as an infrared heater, and thermocompression bonding. The double belt press is
A high pressure heating-cooling under pressure and a liquid pressure type using a heating medium is preferable.

Particularly, in the above-mentioned metal layer laminate, the temperature of the thermocompression bonding zone of a roll laminate or a double belt press is preferably 20 ° C. or more and 400 ° C. or less higher than the glass transition temperature of the thermocompression bonding polyimide. Temperature, especially at a temperature higher than the glass transition temperature of 30 ° C. or higher and a temperature of 400 ° C. or lower under pressure, particularly in the case of a double belt press, followed by cooling under pressure with a cooling zone, preferably, It can be produced by cooling to a temperature lower than the glass transition temperature of the thermocompression-bondable polyimide by 20 ° C. or more, particularly 30 ° C. or more, and laminating.

In the above-mentioned method, the flexible metal foil laminate obtained by thermocompression-cooling under pressure using a double belt press and laminating, has a long length and a width of about 400 mm or more, particularly about 500 mm. Wide adhesive strength above (90 ° peel strength: 0.8kg
/ Cm or more, particularly 1 kg / cm or more), a laminate having a good appearance can be obtained so that wrinkles are not substantially observed on the metal foil surface.

In the metal layer laminate, a polyimide film in which flexible polyimides are laminated and integrated on both sides of a high heat resistant aromatic polyimide layer is subjected to discharge treatment such as plasma discharge, and then deposited by a vapor deposition method, a plating method or the like. Particularly, it can be obtained by forming a base metal layer by a vapor deposition method, forming a copper plating layer on the base metal layer, and forming a metal film.

Lamination of the metal vapor deposition layer can be particularly suitably carried out by a physicochemical vapor deposition method such as a vacuum vapor deposition method, an electron beam vapor deposition method or a sputtering method. As a vapor deposition method, the degree of vacuum is 10 ^-7 to 10 ^-2 Torr.
The vapor deposition rate is about 50 to 5000 Å / sec, and the temperature of the vapor deposition substrate (film) is about 20 to 6
It is preferably about 00 ° C. Among the sputtering methods, the RF magnet sputtering method is particularly suitable, and the degree of vacuum at that time is 1 Torr or less, particularly 10 ⁻³ to
It is about 10 ^-2 Torr and the substrate (film) temperature is 2
0-450 ℃, the formation rate of the layer is 0.5
It is preferably about 500 Å / sec.

As the material of the metal film, chromium, titanium, nickel, molybdenum, zinc, tin, palladium or the like is used as a base layer of the metal vapor deposition layer, and copper or a copper alloy (especially copper) is used as a surface layer thereon. -Nickel alloys) may be used. The thickness of the underlayer is usually about 1 μm or less. The copper plating layer thus obtained is formed. The plating layer may be formed by electrolytic plating alone, electroless plating, and then electrolytic plating. It is preferable that the metal film has a thickness of about 3 μm to 12 μm, particularly about 3 μm to 9 μm. The larger the thickness of the metal film, the more unfavorable for fine patterning. Further, it is preferable that the metal film formation including the above-mentioned sputtering / vapor deposition method is performed by a continuous roll.

From this metal layer laminated body, a metal layer is usually coated by a method known per se, for example, by coating a positive type photoresist on a metal foil of the laminated body and drying, and then exposing to an ultraviolet ray and alkali developing, For example, a resist pattern in which holes having a diameter of 30 to 150 μm are arranged at intervals of 100 to 200 μm.
Then, the metal foil exposed with the ferric chloride-containing etching solution is etched to form a pattern and terminals are provided to obtain a wiring board. Also, using a metal foil etched into a desired pattern as a mask,
The polyimide layer can be formed by a method known per se, for example, Japanese Patent Laid-Open No.
-97081, 20-50% by weight of ethanolamine or iso- or dipropanolamine, 25-40% by weight of potassium hydroxide (KOH), and 25-4 of water.
An etching solution consisting of 0 wt% is brought into contact with the polyimide film at 50 to 80 ° C. for about 5 to 20 minutes (when the polyimide film thickness is 50 μm), preferably using an etching device equipped with an ultrasonic transmitter. By subjecting the polyimide film to chemical treatment, the polyimide film can be chemically etched to form through holes in the film to form a substrate.

Alternatively, the metal layer on one surface is chemically etched to form a pattern having a predetermined shape, and then the remaining polyimide layer is irradiated with a laser using the remaining metal layer as a mask for about 3 to 3 times.
00 μmφ, preferably about 30-300 μmφ, especially about 5
A through hole having a diameter of 0 to 100 μm is formed. Then, after the laser processing portion is desmeared in the same manner as described above, a pattern can be formed on another metal layer to form a substrate.

In forming the metal plating layer, the metal plating conditions are, for example, 50 to 200 g / l (particularly 50 to 100) of metal salt such as copper sulfate as the acid bath composition.
g / l), sulfuric acid 100 to 300 g / l, and optionally a small amount of brightener, and the plating operation conditions are a temperature of about 20 to 30 ° C. and a cathode current density of 2 to 8 A /.
dm2, air agitation, cathode efficiency 95-100%, anode / cathode area ratio 1: 1, cathode copper roll, constant filtration, voltage 6V
The following conditions are preferable. The thickness of the plated metal layer is preferably about 1 μm to 18 μm,
The total metal layer thickness is preferably about 2 to 35 .mu.m, which is the thickness of the metal layer before laser processing plus the above thickness.

The circuit board of the present invention is preferably peeled off after being subjected to perforation processing, preferably perforation processing and cutting processing, according to the terminal portion of the wiring, on an adhesive sheet for a cover ray having a release film. Except for the film, the wiring of the substrate, preferably a flexible printed wiring board, is overlapped with 50 to 200
C., 5 to 100 kgf / cm.sup.2 for about ¹ to 60 minutes, and thermocompression bonding, preferably 10 to 6 at 100 to 200.degree.
Heat for about 0 minutes and cover with an adhesive sheet for cover lei.
It is possible to obtain a printed circuit board. Cover of this invention
The adhesive sheet for lei preferably has a tensile modulus of about 20-5.
It is 0 kgf / mm ² . The circuit board of the present invention has a line insulation resistance value of 1 × 10 ¹⁰ to 1 × 10 ¹⁵ Ω. In addition, the circuit board of the present invention has a soot dive distance of 1
~ 100 mm.

[0055]

EXAMPLES Examples of the present invention will be shown below. In the following examples, parts represent parts by weight, and the measurement of each example was carried out by the test method shown below. Logarithmic viscosity as a measure of molecular weight
(η _inh ) is adjusted to a resin solution by uniformly dissolving in N-methyl-2-pyrrolidone so that the resin component concentration becomes 0.5 g / 100 ml solvent, and the solution viscosity of the solution and the solvent only The solvent viscosity was measured at 30 ° C. using a Canon Fenske type viscometer and determined by a conventional method. For the solid content concentration of the adhesive solution, precisely measure 1 g of the adhesive solution in an aluminum cup,
It was calculated from the weight after heating and drying for 1 hour with a hot air dryer at 200 ° C.

The line-to-line insulation resistance of the circuit board covered with the cover sheet adhesive sheet is in accordance with JIS-C-6471, item 7.4.
It was measured. The tin dip distance of the tin plating solution on the circuit board covered with the cover sheet adhesive sheet is a comb-shaped electrode (165 μm) prepared by using a 35 μm-thick copper foil in accordance with the IPC standard A pattern. Line and space) in the embodiment, after covering (bonding) with an adhesive sheet having a thickness of 50 μm, in the comparative example, a coating agent of 50 μm is used.
After screen-printing to a thickness of m, dip it in plating solution (LT-34 manufactured by Shipley Co., Ltd.) at 70 ° C for 4 minutes, and then remove the part (discolored part) where the plating solution goes into the terminal under the coating. The distance was measured by microscopic observation. The average value of tin dive distance in the measurement data (5 arbitrary points) was displayed. The smaller the tin diving distance is, the more preferable. Adhesive sheet for cover ray
Tensile modulus of elasticity was measured according to ASTM D882.

Reference Example 1 0.7 mol of 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride and methyl were placed in a glass flask having a capacity of 2 liters equipped with a thermometer, a charging port, a distillation outlet and a stirrer. Triglyme (TG) (510 g) was added, the temperature was raised to 160 ° C. in a nitrogen stream to dissolve, and ω, ω′-bis (3-aminopropyl) polydimethylsiloxane (KF-8010, manufactured by Shin-Etsu Silicon Co., Ltd., Amine value 450) 0.
49 moles and 255 g of TG were added and the temperature was raised to 190 ° C to 1
Stir for hours. Thereafter, 0.105 mol of both 3,5-diaminobenzoic acid and 2,2-bis [4- (4-aminophenoxy) phenyl] propane and 254 g of TG were added, and the reaction solution was stirred at 190 ° C. for 15 hours. The η _inh of the polymerization solution after the reaction was 0.2.

Reference Example 2 Polyimide silosiloxane solution 10 produced in Reference Example 1
Epoxy resin (Okaka Shell Epoxy Co., Ltd., Epicote 1002) 12 parts by weight, talc (Nippon Talc Co., Ltd., P-3) 2.6 parts by weight, 2-ethyl-4-
Methyl imidazole (2E4MZ, manufactured by Shikoku Chemicals)
0.52 parts by weight, antifoaming agent (DB-made by Dow Corning)
100) 1.546 parts by weight of solid content 50%
An adhesive solution was prepared.

Example 1 The adhesive solution obtained in Reference Example 2 was uniformly coated on a peelable polyester film (PET film, thickness 38 μm) with a roll coater, and the temperature was gradually increased from 100 ° C. to 150 ° C. The adhesive sheet for cover lei was manufactured by heat-drying in a continuous drying oven heated to 1. When the coating thickness is 60 μm, the adhesive layer thickness is 30 μm and the coating thickness is 1
When the thickness was 00 μm, the adhesive layer thickness was 50 μm. The tensile elastic modulus of these cover sheet adhesive sheets is
All were about 40 kgf / mm ² .

Example 2 A 165 μm line and a press machine adjusted to 100 ° C. were used.
A copper wiring substrate [electrolytic copper foil (35 μm thick) and substrate: U-Pyrex VT film (manufactured by Ube Industries, 25 μm thick, three-layered polyimide film) having pattern-etched terminals and provided with terminals] Using a polyimide-copper foil laminate by the laminating method], and a sheet punched in accordance with the terminal portion of the wiring board to the adhesive sheet for cover layer having a thickness of 50 μm manufactured in Example 1 Set them on top of each other, raise the pressure to 3mpa, and then press at 160 ℃
The temperature was raised to and held at 160 ° C for 15 minutes. The circuit board was taken out from the press and cured by a hot air dryer at 180 ° C. for 30 minutes to obtain a circuit board covered with a warp-free adhesive sheet for cover ray. This is a tin plating solution (made by Shipley, L
After dipping in T-34) at 70 ° C. for 4 minutes, the distance of tin diving was measured with a microscope. The measurement results are shown below. Swing distance: 90 μm

In addition, JIS-C-6471, 7.
A circuit board obtained in the same manner as the copper wiring board (polyimide-copper foil laminate having the same structure as described above) pattern-etched according to item 2 was measured for insulation resistance between lines. The measurement results are shown below. Insulation resistance between wires: 2 × 10 ¹³ Ω

Comparative Example 1 A circuit board covered with a cover film was obtained in the same manner as in Example 1 except that a cover film having a cover film (CKSE manufactured by Nikkan Kogyo Co., Ltd.) was used.
The circuit board was warped. The measurement results are shown below. Insulation resistance between wires; 1.1 × 10 ⁷ Ω

Comparative Example 2 A copper wiring board pattern-etched to a line and space of 165 μm using the adhesive solution obtained in Reference Example 2 was used to screen except a terminal portion using a printing plate. Coating with an adhesive-cured film in the same manner as in Example 2 except that the coating was performed by printing and cured by heating at 160 ° C. for 1 hour.
The obtained circuit board was obtained. The distance of diving was measured. The measurement results are shown below. Swing distance: 200 μm

[0064]

EFFECTS OF THE INVENTION The circuit board according to the present invention has no warpage, is excellent in inter-line insulation, has a small penetration distance of suds plating during gold plating, and can improve the quality of the final product of the circuit board.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a circuit board covered by an adhesive sheet for a cover ray which is an example of the present invention.

[Explanation of symbols]

1 circuit board 2 Cover sheet adhesive sheet 3 Substrate polyimide film 4 copper foil

Claims (9)

[Claims] 1. A cover having a thickness of 3 μm to 100 μm.
A circuit board whose wiring is covered by an adhesive sheet for a cover ray that does not have a film. 2. The circuit board according to claim 1, wherein the cover sheet adhesive cover comprises a polyimidesiloxane having a group reactive with an epoxy group, a small amount of an epoxy resin, and imidazoles. 3. The circuit board according to claim 1, wherein the cover sheet adhesive sheet is covered with a flexible printed wiring board by heat-pressing after perforating. 4. The wiring is obtained from a polyimide-copper laminate of all-polyimide in which a polyimide layer and a copper layer are laminated by a laminating method, a casting method or a metal deposition method-copper plating method. The circuit board according to claim 1. 5. The wiring is copper-plated on a through hole formed by laser processing or chemical etching on a polyimide layer of a polyimide-copper laminate, and further metal-plated. The described circuit board. 6. The circuit board according to claim 1, wherein the cover sheet adhesive sheet is covered with a flexible printed wiring board by thermocompression bonding after punching and cutting. 7. A circuit board according to claim 1,
An adhesive sheet for cover lei, in which a peelable film is laminated on both sides of an adhesive. 8. The adhesive contains a black pigment for light shielding.
An adhesive sheet for cover lei according to item 1. 9. The adhesive sheet for cover lei according to claim 7, wherein the peelable film is a polyester film subjected to a peeling treatment.