JP2011148979A - Epoxy resin composition for printed wiring board, resin film, prepreg, resin sheet with metal foil, and flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition for a printed wiring board, enhancing all of storage stability, adhesiveness, flexibility, filling property and anti-discoloring property. <P>SOLUTION: The epoxy resin composition for a printed wiring board contains, as essential components, (A) an epoxy resin, (B) an epoxy resin curing agent, (C) a carbodiimide-modified soluble polyamide, and (D) a dye. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention uses an epoxy resin composition for a printed wiring board, a resin film, a prepreg, a resin sheet with a metal foil (metal foil with a resin), and the like used for manufacturing a printed wiring board such as a flexible printed wiring board. The present invention relates to a formed flexible printed wiring board.

  Many flexible printed wiring boards are used in small and thin electronic devices. Recently, the demand for multilayered flexible printed wiring boards has increased due to the demand for higher density and lower thickness.・ Cost is severe. Conventionally, bonding sheets and coverlays are known as multilayered materials for flexible printed wiring boards. These bonding sheets and coverlays used as insulating build-up materials have not only storage stability, press-formability such as through-holes and circuit fillability, but also flexibility, heat resistance, and chemical resistance as flexible printed wiring boards. Electrical insulation is required. Accordingly, a resin composition obtained by blending NBR or acrylic rubber having excellent flexibility with an epoxy resin having excellent insulation, heat resistance, and chemical resistance is used for bonding sheets and coverlays.

  However, the varnish and sheet storage stability of such a resin composition is insufficient, and the electric insulation, heat resistance, and chemical resistance of the flexible printed wiring board obtained using the resin composition are not satisfactory. . For this reason, it is also possible to use a resin composition obtained by blending an epoxy resin with polyamideimide or polyamide, which is superior in chemical resistance, heat resistance, insulation, flame retardancy and flexibility than synthetic rubber such as NBR and acrylic rubber. However, the press formability such as varnish storage stability, sheet storage stability, through-hole and circuit filling properties is still not sufficient. Moreover, when the storage stability and press formability are improved, other characteristics that have been favorable are deteriorated. For example, there is a problem that discoloration occurs when a flexible printed wiring board is immersed in a solder bath.

JP-A-11-140164

  The present invention has been made in view of the above points, an epoxy resin composition for printed wiring boards, a resin film, which can enhance storage stability, adhesion, flexibility, filling properties, and discoloration resistance, An object of the present invention is to provide a prepreg, a resin sheet with a metal foil, and a flexible printed wiring board.

  The epoxy resin composition for printed wiring boards according to the present invention contains (A) an epoxy resin, (B) an epoxy resin curing agent, (C) a carbodiimide-modified soluble polyamide, and (D) a dye as essential components. It is a feature.

  In the epoxy resin composition for printed wiring boards, the content of the component (C) is preferably 20 to 70% by mass with respect to the total amount of the components (A), (B), and (C).

  In the epoxy resin composition for a printed wiring board, an epoxy resin having a naphthalene skeleton is preferably used as the component (A).

  In the epoxy resin composition for printed wiring boards, at least one of those represented by the following structural formulas (1) to (3) is preferably used as the epoxy resin having a naphthalene skeleton.

  In the epoxy resin composition for printed wiring boards, it is preferable that at least one of aminotriazine novolak resin and dicyandiamide represented by the following structural formula (4) is used as the component (B).

  It is preferable that the epoxy resin composition for printed wiring boards contains a phenoxy resin.

  The epoxy resin composition for printed wiring boards preferably contains at least one of a phosphorus-modified epoxy resin, a phosphorus-modified phenoxy resin, and a phosphorus-based flame retardant.

  The resin film according to the present invention is characterized in that the epoxy resin composition for a printed wiring board is formed into a film shape.

  The prepreg according to the present invention is characterized in that the substrate is impregnated with the epoxy resin composition for a printed wiring board and is in a semi-cured state.

  The resin sheet with a metal foil according to the present invention is characterized in that the epoxy resin composition for a printed wiring board is applied to the metal foil and is in a semi-cured state.

  The flexible printed wiring board according to the present invention is formed using at least one of the resin film, the prepreg, and the resin sheet with metal foil.

  According to the present invention, the carbodiimide-modified soluble polyamide can enhance all of storage stability, adhesion, flexibility, filling property, and discoloration resistance.

  Embodiments of the present invention will be described below.

  In the present invention, an epoxy resin composition for a printed wiring board contains (A) an epoxy resin, (B) an epoxy resin curing agent, (C) a carbodiimide-modified soluble polyamide, and (D) a dye as essential components.

  As the epoxy resin as the component (A), for example, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, oxidation type epoxy resin and the like can be used. Among these, examples of the glycidyl ether type epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, alcohol type epoxy resin and the like. Examples of the glycidyl ester type epoxy resin include hydrophthalic acid type epoxy resins and dimer acid type epoxy resins. Examples of the glycidylamine type epoxy resin include aromatic amine type epoxy resins and aminophenol type epoxy resins. Moreover, as an oxidation type epoxy resin, an alicyclic epoxy resin etc. can be illustrated. Furthermore, an epoxy resin having a naphthalene skeleton, a novolac type epoxy resin having a phenol skeleton and a biphenyl skeleton (biphenyl novolac epoxy resin), a phosphorus-modified epoxy resin (described later), etc. can be used, but one containing no halogen is used. preferable. In particular, as the component (A), it is preferable to use an epoxy resin having a naphthalene skeleton. When such an epoxy resin is used, the heat resistance, migration resistance, and chemical resistance of the flexible printed wiring board can be improved. Among these, as the epoxy resin having a naphthalene skeleton, it is preferable to use at least one of those represented by the structural formulas (1) to (3). When such an epoxy resin is used, the heat resistance, migration resistance, and chemical resistance of the flexible printed wiring board can be further enhanced as compared with the case of using other epoxy resins.

  As the epoxy resin curing agent as component (B), for example, polyamines, modified polyamines, acid anhydrides, hydrazine derivatives, polyphenols and the like can be used. Among these, examples of the polyamine-based curing agent include aliphatic polyamines, alicyclic polyamines, and aromatic polyamines. Among these, examples of the aliphatic polyamine include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, m-xylenediamine, trimethylhexamethylenediamine, 2-methylpentamethylenediamine, and diethylaminopropylamine. Examples of the alicyclic polyamines include isophorone diamine, 1,3-bisaminomethylcyclohexane, bis (4-aminocyclohexyl) methane, norbornene diamine, 1,2-diaminocyclohexane, and laromine. Examples of aromatic polyamines include diaminodiphenylmethane, metaphenylenediamine, and diaminodiphenylsulfone. Examples of acid anhydrides include hexahydrophthalic anhydride, methyl tetrahydro anhydride, methyl hexahydrophthalic anhydride, methyl nadic acid anhydride, hydrogenated methyl nadic acid anhydride, trialkyltetrahydrophthalic anhydride, methylcyclohexene tetracarboxylic acid. Examples include dianhydride, trimellitic anhydride, pyromellitic acid free, benzophenone tetracarboxylic dianhydride, aliphatic dibasic acid polyanhydride, and the like. Examples of the polyphenol-based curing agent include phenol novolak, xylene novolak, bis A novolak, triphenylmethane novolak, biphenyl novolak, dicyclopentadienephenol novolak, and terpene phenol novolak. Further, aminotriazine novolac resins, novolac-type phenol resins and the like can be used. In particular, as the component (B), it is preferable to use at least one of aminotriazine novolak resin and dicyandiamide represented by the structural formula (4). When such an epoxy resin curing agent is used, the long-term product storage stability of resin films, prepregs, and resin sheets with metal foils can be improved, and the flame resistance and chemical resistance of flexible printed wiring boards can be increased. It is something that can be done. In addition, it is preferable that content of (B) component is 10-45 mass% with respect to the total amount of (A) (B) (C) component.

  As the carbodiimide-modified soluble polyamide as component (C), it is possible to use a product obtained by reacting a soluble polyamide and a carbodiimide compound at a reaction temperature of 50 to 250 ° C. in the presence or absence of a solvent. it can.

  The soluble polyamide is completely dissolved in an amount of 1 part by mass or more, preferably 5 parts by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of a mixture of alcohol and aromatic and / or ketone organic solvents. It is possible.

  Examples of the alcohol include methanol, ethanol, isopropyl alcohol and the like. Examples of the aromatic solvent include benzene and toluene. Examples of the ketone solvent include cyclohexanone. , 2-butanone, cyclopentanone and the like. These alcohols, aromatic solvents and ketone solvents preferably have a boiling point of 130 ° C. or lower.

  The soluble polyamide can be obtained by solubilizing the polyamide. As the solubilization method, for example, a method in which hydrogen atoms of amide bonds of various polyamides are partially substituted with methoxymethyl groups can be exemplified. When a methoxy group is introduced into a polyamide, the hydrogen bonding ability of the amide group is lost, and the crystallinity of the polyamide is inhibited, so that the solubility in a solvent is increased. Examples of the solubilization method include a method of introducing a polyether or polyester into a polyamide molecule before solubilization to obtain a copolymer. Examples of the polyamide before solubilization include nylon 6, nylon 66, nylon 610, nylon 11, nylon 12, and nylon 46.

  Specific examples of the soluble polyamide include “Zytel 61” (manufactured by DuPont), “Versalon” (manufactured by General Mills), “Amilan CM4000” (manufactured by Toray Industries, Inc.), and “Amilan CM8000” (manufactured by Toray Industries, Inc.). , “PA-100” (manufactured by Fuji Kasei Kogyo Co., Ltd.), “Toresin” (manufactured by Nagase ChemteX Corporation), and the like.

  The carbodiimide compound is a compound having one or more carbodiimide groups in the molecule, and examples thereof include a monocarbodiimide compound and a polycarbodiimide compound. For example, an organic phosphorus compound or an organometallic compound is used as a catalyst. Isocyanates can be synthesized by a decarboxylation condensation reaction at a temperature of about 70 ° C. or higher in a solvent-free or inert solvent.

  Examples of the monocarbodiimide compound include dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, di-t-butylcarbodiimide, di-β-naphthylcarbodiimide and the like. Among these, dicyclohexylcarbodiimide or diisopropylcarbodiimide is preferable from the viewpoint of industrial availability.

  In addition, as the polycarbodiimide compound, those produced by various methods can be used, but basically, a conventional method for producing polycarbodiimide (for example, US Pat. No. 2,941,956, J. Org). Chem. 28, 2069-2075 (1963), Chemical Review 1981, Vol. 81 No. 4, p619-621) can be used.

  Examples of the organic diisocyanate that is a synthetic raw material for producing a polycarbodiimide compound include aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and mixtures thereof. Specifically, 1,5- Naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate , 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate mixture, hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophoro Illustrate diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, methylcyclohexane diisocyanate, tetramethylxylylene diisocyanate, 2,6-diisopropylphenyl diisocyanate, 1,3,5-triisopropylbenzene-2,4-diisocyanate, etc. Can do.

  Of these, aliphatic (including alicyclic) organic diisocyanates are preferable from the viewpoint of improving flexibility and moisture resistance, and particularly ilophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, tetramethylxylylene diene. Isocyanates and mixtures thereof are more preferred.

  Moreover, when manufacturing the said polycarbodiimide compound, a polymerization reaction can be stopped on the way by cooling etc., and it can control to a suitable polymerization degree. In this case, the terminal is an isocyanate group. Furthermore, in order to control to an appropriate degree of polymerization, there is a method of sealing all or part of the remaining terminal isocyanate groups using a compound that reacts with the terminal isocyanate group of the polycarbodiimide compound, such as a monoisocyanate compound. . By controlling the degree of polymerization, compatibility with soluble polyamide and storage stability can be enhanced, which is preferable in terms of quality improvement.

  Examples of the monoisocyanate compound for sealing the end of such a polycarbodiimide compound and controlling the degree of polymerization thereof include phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, naphthyl isocyanate and the like. be able to.

Further, the end-capping agent that seals the end of the polycarbodiimide compound and controls the degree of polymerization thereof is not limited to the monoisocyanate compound, but an active hydrogen compound that can react with an isocyanate group, for example, ( i) an aliphatic, aromatic or alicyclic compound having an —OH group, methanol, ethanol, phenol, cyclohexanol, N-methylethanolamine, polyethylene glycol monomethyl ether, polypropylene glycol monomethyl ether; (ii) = diethylamine with an NH group, dicyclohexylamine; butylamine with (iii) -NH ₂ group, cyclohexylamine; succinic acid having a (iv) -COOH group, benzoic acid, cyclohexane acid, ethyl having (v) -SH group Mercaptans, ants Lumercaptan, thiophenol; (vi) compounds having an epoxy group; (vii) acid anhydrides such as acetic anhydride, methyltetrahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

The decarboxylation condensation reaction of the organic diisocyanate is carried out in the presence of a suitable carbodiimidization catalyst. Examples of the carbodiimidization catalyst that can be used include organic phosphorus compounds, organometallic compounds [general formula M- (OR) _n [M is titanium (Ti), sodium (Na), potassium (K), vanadium (V), tungsten (W), hafnium (Hf), zirconium (Zr), lead (Pb), manganese (Mn), nickel (Ni), calcium (Ca), barium (Ba) and the like, R represents an alkyl group or aryl group having 1 to 20 carbon atoms, and n represents a valence of M] From the viewpoint of activity, phospholene oxides are preferable for organophosphorus compounds, and titanium, hafnium and zirconium are preferred for organometallic compounds. Rukokishido are preferred.

  Specific examples of the phosphorene oxides include 3-methyl-1-phenyl-2-phospholene-1-oxide, 3-methyl-1-ethyl-2-phospholene-1-oxide, 1,3- Dimethyl-2-phospholene-1-oxide, 1-phenyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, 1-methyl-2-phospholene-1-oxide or a double of these Examples of the bond isomers are 3-methyl-1-phenyl-2-phospholene-1-oxide, which is easily available industrially.

  The carbodiimide compound is not particularly limited as long as it has one or more carbodiimide groups in the molecule having the functions as described above. From the viewpoint, a polycarbodiimide compound having two or more carbodiimide groups in the molecule, such as 4,4′-dicyclohexylmethanecarbodiimide, is preferred, and an aliphatic or alicyclic polycarbodiimide compound is more preferred. Moreover, 2-30 are preferable and, as for a polymerization degree, 2-20 are more preferable. A polymerization degree of 2 or more is preferable from the viewpoint of heat resistance, and a polymerization degree of 20 or less is preferable from the viewpoint of compatibility.

  The carbodiimide-modified soluble polyamide as component (C) is obtained by reacting the soluble polyamide with a carbodiimide compound in the presence or absence of a solvent, and reactive functional groups such as a carboxyl group and an amino group that the soluble polyamide has, and It can be obtained by reacting a carbodiimide group or an isocyanate group of a carbodiimide compound that can react with the carbodiimide compound.

  The method for reacting the soluble polyamide with the carbodiimide compound is not particularly limited, but can be performed in the presence or absence of a solvent.

  Examples of the method of reacting in the presence of a solvent include a method of reacting after dissolving a soluble polyamide and a carbodiimide compound in a solvent, and a method of reacting by heating and stirring the soluble polyamide and the carbodiimide compound is preferable. A method in which a carbodiimide compound is added to a solution obtained by dissolving a soluble polyamide in a solvent and reacted by heating and stirring under reflux is more preferable. The carbodiimide-modified soluble polyamide can be obtained by removing the solvent from the solution thus obtained under normal pressure or reduced pressure.

  As a method of reacting in the absence of a solvent, for example, a method in which a soluble polyamide is melted to a melting point or higher and then mixed and reacted, or a soluble polyamide and a carbodiimide compound are melted and kneaded by a twin screw extruder. The method of making it react can be mentioned.

  When reacting a soluble polyamide and a carbodiimide compound, it is preferable that the reaction system does not contain a compound that inhibits carbodiimide modification, and the reaction system contains only a carbodiimide compound, a soluble polyamide, and a solvent used as necessary. Is more preferable. Specific examples of the compound that inhibits the carbodiimide modification include an epoxy resin, an amine resin, a melamine resin, and a phenol resin.

  The time for reacting the soluble polyamide with the carbodiimide compound varies depending on the type of the soluble polyamide or carbodiimide compound to be used, the reaction method, the reaction temperature, etc., but is, for example, about 1 to 500 minutes, and 5 to 200 minutes. preferable.

  The temperature at which the soluble polyamide reacts with the carbodiimide compound also varies depending on the type of the soluble polyamide or carbodiimide compound used, the reaction method, the reaction temperature, etc., but is, for example, 50 to 250 ° C., and the soluble polyamide and carbodiimide compound are mixed with the solvent. In the case of reacting in the presence, it is preferably 50 to 150 ° C, more preferably 70 to 130 ° C. Moreover, when reacting soluble polyamide and a carbodiimide compound in absence of a solvent, it is preferable that it is 130-250 degreeC, and it is more preferable that it is 150-220 degreeC. If the reaction temperature is less than 50 ° C, the reaction between the soluble polyamide and the carbodiimide compound is slow, and it takes time to modify the soluble polyamide, which is not industrially preferable. If the reaction temperature exceeds 250 ° C, deterioration due to decomposition of the resin is likely to occur. Become.

  In addition, by making soluble polyamide and a carbodiimide compound react as mentioned above, soluble polyamide is modified | denatured and it becomes a carbodiimide modified soluble polyamide. For example, as the above reaction proceeds, the carbodiimide group of the carbodiimide compound decreases, so when comparing the reaction product with the product by infrared measurement, the peak of the carbodiimide group observed in the reaction product decreases. is doing. In addition, when differential thermogravimetric measurement is performed on the reactant and product, multiple endothermic peaks of the reactant, such as amide resin and carbodiimide resin, are observed, but the endothermic peaks of the product are aggregated into one. The From the above, it can be confirmed that the soluble polyamide has been modified.

  The carbodiimide-modified soluble polyamide obtained as described above is excellent in storage stability as compared with a composition comprising a soluble polyamide and a carbodiimide compound. That is, in the case of the above composition, thickening of the solution occurs when it is made into a solution, and further gelation is achieved, whereas the modified one shows no change such as thickening even in the solution state. And can be stored for a long time.

  The addition amount of the carbodiimide compound is preferably 0.5 to 20 parts by mass and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the soluble polyamide. If the addition amount is less than 0.5 parts by mass, the moisture resistance and heat resistance may not be sufficiently improved, and if it exceeds 20 parts by mass, the plasticity may become too high or the impact resistance may be impaired. is there.

  And it is preferable that content of the carbodiimide modified | denatured soluble polyamide which is (C) component is 20-70 mass% with respect to the total amount of (A) (B) (C) component. When the content of the component (C) is within this range, the flexibility and chemical resistance of the flexible printed wiring board can be improved. However, if the content of the component (C) is less than 20% by mass, the flexibility may be lowered. Conversely, if the content of the component (C) exceeds 70% by mass, flame retardancy and heat resistance are likely to occur. May decrease.

  Examples of the dye as component (D) include C.I. I. Solvent Black 7, C.I. I. Solvent Black 3, C.I. I. Solvent Red 3, C.I. I. Solvent Yellow 14 or the like can be used. When such a dye is used, discoloration does not occur even when the flexible printed wiring board is immersed in a solder bath at 260 to 288 ° C., and discoloration resistance can be improved. In addition, it is preferable that content of (D) component is 0.01-1 mass% with respect to the epoxy resin composition whole quantity for printed wiring boards.

  In addition to the components (A), (B), (C), and (D), the epoxy resin composition for printed wiring boards preferably contains a phenoxy resin. As the phenoxy resin, bisphenol A type phenoxy resin, bisphenol A / bisphenol F type copolymer phenoxy resin, phosphorus-modified phenoxy resin (described later), and the like can be used. This phenoxy resin can further enhance the flexibility of the flexible printed wiring board. In addition, it is preferable that content of a phenoxy resin is 5-30 mass% with respect to the epoxy resin composition for printed wiring boards whole quantity.

  Furthermore, it is preferable that the epoxy resin composition for printed wiring boards contains at least one of phosphorus-based flame retardants such as phosphorus-modified epoxy resin, phosphorus-modified phenoxy resin, and phosphazene. Here, as the phosphorus-modified epoxy resin, for example, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 1,4-naphthoquinone are reacted, and cresol novolac resin is further reacted. What was obtained can be used. In addition, as the phosphorus-modified phenoxy resin, one having a molecular skeleton composed mainly of phenoxy resin and containing several phosphorus elements (for example, about 1 to 5) in 1 mol of phosphorus-containing phenoxy resin is used. Can do. As the phosphorus-based flame retardant, in addition to phosphazene, for example, monomeric phosphate ester, condensed phosphate ester, reactive phosphorus flame retardant, phosphate, phosphazene compound, and the like can be used. Among these, as the monomeric phosphate ester, triphenyl phosphate, tricresyl phosphate, trixinyl phosphate, triethyl phosphate, cresyl diphenyl phosphate, xylyl diphenyl phosphate, cresyl bis (di-2,6-xylenyl) phosphate, 2- Examples thereof include ethylhexyl diphenyl phosphate. Examples of the condensed phosphate ester include resorcinol bis (diphenyl) phosphate, bisphenol A bis (diphenyl) phosphate, bisphenol A bis (dicresyl) phosphate, resorcinol bis (di-2,6-xylenyl) phosphate, and the like. it can. Examples of reactive phosphorus flame retardants include bisphenol A bisphenyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 2- (diphenylphosphinyl) hydroquinone. can do. Examples of the phosphate include melamine phosphate, dimelamine phosphate, melamine pyrophosphate, dimelamine pyrophosphate, melamine polyphosphate, and ethylenediamine phosphate. Examples of the phosphazene compound include phosphonitrile phenyl ester, cyanophenol / phenol mixed substituted cyclophosphazene, phosphonitrile chloride / hydroquinone / phenol condensate, and the like. By using such a thing, a flame retardance can further be improved. In addition, it is preferable that the sum total of content of a phosphorus modified epoxy resin, a phosphorus modified phenoxy resin, and a phosphorus flame retardant is 10-40 mass% with respect to the epoxy resin composition whole quantity for printed wiring boards.

  And the epoxy resin composition for printed wiring boards contains the components (A), (B), (C), and (D) as essential components, and further phenoxy resin, phosphorus-modified epoxy resin, phosphorus-modified phenoxy resin, and phosphorus-based flame retardant. It can be prepared by blending a curing accelerator such as 2-ethyl-4-methylimidazole as an optional component.

  In addition to the above components, additives such as pigments, leveling agents, antifoaming agents, ultraviolet absorbers, antioxidants and ion scavengers are added to the epoxy resin composition for printed wiring boards as necessary. May be.

  In the epoxy resin composition for a printed wiring board thus obtained, the carbodiimide-modified soluble polyamide obtained by reacting an unreacted group (amino group or carboxyl group) of polyamide with carbodiimide is used as an epoxy resin or epoxy. By blending with a resin curing agent and a dye, storage stability, adhesion, flexibility, fillability, and discoloration resistance can all be improved. That is, by reacting unreacted groups (amino group and carboxyl group) originating from the raw material of polyamide with carbodiimide, the reaction between the polyamide resin and the epoxy resin is prevented from being promoted at a low temperature, and varnish storage stability is maintained, and coating is performed. The storage stability and press moldability of various sheets (resin film, prepreg, resin sheet with metal foil described later) obtained by processing and drying can be satisfied. And varnish and sheet workability of epoxy resin composition for printed wiring board, workability (storage stability and press formability), and various characteristics of flexible printed wiring board (adhesion, flexibility, filling property, discoloration resistance) Etc.).

  A sheet such as a resin film, a prepreg, and a resin sheet with a metal foil can be produced using the epoxy resin composition for a printed wiring board as a varnish as appropriate, and further a flexible printed wiring board is produced using this sheet. be able to.

  That is, the resin film can be produced by forming the epoxy resin composition for a printed wiring board into a film shape and heating and drying it until it is in a semi-cured state (B stage state). The prepreg can be produced by impregnating a substrate such as a glass cloth with an epoxy resin composition for a printed wiring board, and heating and drying it until it is in a semi-cured state. Moreover, the resin sheet with a metal foil can be produced by applying an epoxy resin composition for a printed wiring board to a metal foil such as a copper foil, and heating and drying it to form a semi-cured adhesive resin layer. it can. Furthermore, the flexible printed wiring board is formed using at least one of a resin film, a prepreg, and a resin sheet with a metal foil. Specifically, for example, a polyimide film or the like is used as a core material. A flexible printed wiring board can be manufactured by laminating any one of a resin film, a prepreg, and a resin sheet with a metal foil on one or both sides of the material, and then performing circuit formation and interlayer connection as appropriate. .

  In the thus obtained resin film, prepreg, resin sheet with metal foil, and flexible printed wiring board, all are formed using the above epoxy resin composition for printed wiring board as a material. Flexibility, fillability, and discoloration resistance can all be improved. Furthermore, since the reaction between the epoxy group and the carbodiimide group also proceeds during high-temperature press molding, a flexible printed wiring board having excellent heat resistance and chemical resistance can be obtained. In addition, the resin sheet with metal foil can be used as a build-up insulating sheet similarly to a bonding sheet or a coverlay, and can also be used as a coverlay having a shielding function.

  Hereinafter, the present invention will be specifically described by way of examples.

(Synthesis of carbodiimide compounds)
By reacting 590 g of 4,4′-dicyclohexylmethane diisocyanate, 62.6 g of cyclohexyl isocyanate and 6.12 g of carbodiimidization catalyst (3-methyl-1-phenyl-2-phospholene-1-oxide) at 180 ° C. for 48 hours, As a carbodiimide compound, 4,4′-dicyclohexylmethane carbodiimide resin (degree of polymerization = 10) was obtained.

((C) Synthesis of carbodiimide-modified soluble polyamide)
In a 1-liter separable flask, 50.0 g of ester copolymerized amide resin (trade name: “CM8000”, manufactured by Toray Industries, Inc.) and 450.0 g of a mixed solvent of isopropyl alcohol and toluene (mass mixing ratio 4: 6) are added. In addition, it was dissolved by stirring. 5.0 g of the above carbodiimide compound (4,4′-dicyclohexylmethane carbodiimide resin) was added to the solution thus obtained, the flask was immersed in an oil bath at 120 ° C., heated and stirred for 3 hours under reflux, and then dried under reduced pressure. Then, by removing the solvent, a carbodiimide-modified soluble polyamide serving as component (C) was obtained.

When the infrared spectrophotometric measurement was performed on the (C) carbodiimide-modified soluble polyamide obtained as described above, an absorption peak indicating the presence of a carbodiimide group was observed at 2120 cm ⁻¹ . Further, when differential scanning calorimetry was performed on the (C) carbodiimide-modified soluble polyamide, one endothermic peak was observed. The above (C) carbodiimide-modified soluble polyamide had a glass transition temperature of 120 ° C., a 5% weight loss temperature of 320 ° C., and a solution viscosity of 860 mPa · s.

  Next, varnishes of the epoxy resin compositions for printed wiring boards of Examples 1 to 13 and Comparative Examples 1 and 2 were prepared according to the composition described in [Table 1] below. In addition, all the mixing | blendings of the following [Table 1] are solid content ratios.

Example 1
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (aminotriazine novolak resin represented by the above structural formula (4)), (C ) A carbodiimide-modified soluble polyamide, (D) dye (dye (1)), curing accelerator, phosphorus flame retardant (phosphazene) in a container and mixed to obtain a solid content of 33% by weight epoxy resin for printed wiring boards A varnish of the composition was prepared.

(Example 2)
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (aminotriazine novolak resin represented by the above structural formula (4)), (C ) A carbodiimide-modified soluble polyamide, (D) dye (dye (1)), curing accelerator, phosphorus flame retardant (phosphazene) in a container and mixed to obtain a solid content of 33% by weight epoxy resin for printed wiring boards A varnish of the composition was prepared.

(Example 3)
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (aminotriazine novolak resin represented by the above structural formula (4)), (C ) Epoxy resin for printed wiring board having a solid content of 27% by mass by mixing carbodiimide-modified soluble polyamide, (D) dye (dye (1)), curing accelerator and phosphorus flame retardant (phosphazene) in a container. A varnish of the composition was prepared.

Example 4
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (aminotriazine novolak resin represented by the above structural formula (4)), (C ) Epoxy resin for printed wiring boards having a solid content of 25% by mass by mixing carbodiimide-modified soluble polyamide, (D) dye (dye (1)), curing accelerator and phosphorus flame retardant (phosphazene) in a container. A varnish of the composition was prepared.

(Example 5)
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (aminotriazine novolak resin represented by the above structural formula (4)), (C ) A carbodiimide-modified soluble polyamide, (D) dye (dye (1)), curing accelerator, and phosphorus flame retardant (phosphazene) in a container and mixed to obtain an epoxy resin for a printed wiring board having a solid content of 19% by mass A varnish of the composition was prepared.

(Example 6)
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (aminotriazine novolak resin represented by the above structural formula (4)), (C ) Epoxy resin for printed wiring board having a solid content of 27% by mass by mixing carbodiimide-modified soluble polyamide, (D) dye (dye (1)), curing accelerator and phosphorus flame retardant (phosphazene) in a container. A varnish of the composition was prepared.

(Example 7)
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (aminotriazine novolak resin represented by the above structural formula (4)), (C ) A carbodiimide-modified soluble polyamide, (D) dye (dye (1)), phenoxy resin, curing accelerator, phosphorus flame retardant (phosphazene) in a container and mixed to obtain a printed wiring board having a solid content of 29% by mass An epoxy resin composition varnish was prepared.

(Example 8)
(A) Epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (novolak type phenol resin), (C) carbodiimide-modified soluble polyamide, (D) dye A varnish of an epoxy resin composition for a printed wiring board having a solid content of 27% by mass was prepared by mixing (dye (1)), a curing accelerator, and a phosphorus-based flame retardant (phosphazene) in a container.

Example 9
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (2)), (B) epoxy resin curing agent (aminotriazine novolak resin represented by the above structural formula (4)), (C ) A carbodiimide-modified soluble polyamide, (D) dye (dye (1)), curing accelerator and phosphorus flame retardant (phosphazene) are mixed in a container to obtain a 22% by mass solid content epoxy resin for printed wiring boards. A varnish of the composition was prepared.

(Example 10)
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (3)), (B) epoxy resin curing agent (aminotriazine novolac resin represented by the above structural formula (4)), (C ) A carbodiimide-modified soluble polyamide, (D) dye (dye (1)), curing accelerator and phosphorus flame retardant (phosphazene) are mixed in a container to obtain a 22% by mass solid content epoxy resin for printed wiring boards. A varnish of the composition was prepared.

(Example 11)
(A) Epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1) and phosphorus-modified epoxy resin), (B) epoxy resin curing agent (aminotriazine novolak represented by the above structural formula (4) (Resin), (C) carbodiimide-modified soluble polyamide, (D) dye (dye (1)), curing accelerator, and phosphorus flame retardant (phosphazene) in a container and mixed to obtain a print having a solid content of 26% by mass. A varnish of an epoxy resin composition for a wiring board was prepared.

(Example 12)
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (aminotriazine novolak resin represented by the above structural formula (4)), (C ) A carbodiimide-modified soluble polyamide, (D) dye (dye (2)), curing accelerator, phosphorus flame retardant (phosphazene), and phosphorus-modified phenoxy resin are mixed in a container to print a solid content of 26% by mass. A varnish of an epoxy resin composition for a wiring board was prepared.

(Example 13)
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (dicyandiamide), (C) carbodiimide-modified soluble polyamide, (D) dye (dye ( 2)), a curing accelerator and a phosphorus flame retardant (phosphazene) were placed in a container and mixed to prepare a varnish of an epoxy resin composition for a printed wiring board having a solid content of 26% by mass.

(Comparative Example 1)
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (aminotriazine novolak resin represented by the above structural formula (4)), soluble polyamide A varnish of an epoxy resin composition for printed wiring boards having a solid content of 26% by mass was prepared by mixing a curing accelerator and a phosphorus-based flame retardant (phosphazene) in a container.

(Comparative Example 2)
(A) epoxy resin (epoxy resin having a naphthalene skeleton represented by the above structural formula (1)), (B) epoxy resin curing agent (aminotriazine novolak resin represented by the above structural formula (4)), soluble polyamide A varnish of an epoxy resin composition for a printed wiring board having a solid content of 22% by mass was prepared by mixing a curing accelerator in a container.

  In addition, each component shown in the following [Table 1] is as follows.

(A) Epoxy resin having naphthalene skeleton (Structural Formula (1)): Epoxy resin not containing halogen and having naphthalene skeleton (“NC-7000L” manufactured by Nippon Kayaku Co., Ltd., with the above structural formula (1)) Represented)
(A) Epoxy resin having naphthalene skeleton (Structural Formula (2)): Epoxy resin not containing halogen and having naphthalene skeleton (“EXA-9900” manufactured by DIC Corporation, represented by the above structural formula (2)) Stuff)
(A) Epoxy resin having naphthalene skeleton (structural formula (3)): epoxy resin not containing halogen and having naphthalene skeleton (“HP-4700” manufactured by DIC Corporation, represented by the above structural formula (3)) Stuff)
(A) Phosphorus-modified epoxy resin: Phosphorus-modified epoxy resin (“FX-305EK70” manufactured by Tohto Kasei Co., Ltd.), which was dissolved in methyl ethyl ketone, and the resin solid content was 70% by mass.

  (B) Phenol novolac-type aminotriazine novolak resin (Structural Formula (4), R = H): Phenol novolac-type aminotriazine novolak resin (“LA-7052” manufactured by DIC Corporation), represented by the above structural formula (4) And R is H), which was dissolved in methyl ethyl ketone, and the resin solid content was 60% by mass.

(B) Cresol novolac-type aminotriazine novolak resin (Structural Formula (4), R = CH ₃ ): Cresol novolac-type aminotriazine novolak resin (“LA-3018-50P” manufactured by DIC Corporation, the above structural formula (4) And R is CH ₃ ), dissolved in propylene glycol monomethyl ether, and the resin solid content was 50% by mass.

  (B) Novolak type phenol resin: A phenol novolak resin (manufactured by DIC Corporation, “TD-2090-60M”) dissolved in methyl ethyl ketone, and the resin solid content was 60% by weight.

(B) Dicyandiamide: manufactured by Nacalai Tesque Co., Ltd. (C) Carbodiimide-modified soluble polyamide: synthesized as described above. In addition, this was melt | dissolved in the mixed solvent (mass mixing ratio 4: 6) of isopropyl alcohol and toluene, and solid content concentration was 11 mass%.

-(D) Dye (1) (Chuo Synthetic Chemical Co., Ltd. "OIL BLACK SF" (CI Solvent Black 7))
-(D) Dye (2) (Chuo Synthetic Chemical Co., Ltd. "OIL BLACK 141" (CI Solvent Black 3))
Soluble polyamide: ester copolymerized amide resin (“CM-8000” manufactured by Toray Industries, Inc.), which is dissolved in a mixed solvent of isopropyl alcohol and toluene (mass mixing ratio 4: 6), and has a solid content The concentration was 10% by mass.

  Phenoxy resin: A phenoxy resin (“YP-50” manufactured by Tohto Kasei Co., Ltd.) dissolved in methyl ethyl ketone, and the resin solid content was 65% by mass.

Curing accelerator: 2-ethyl-4-methylimidazole (“2E4MZ” manufactured by Shikoku Chemicals Co., Ltd.)
Phosphazene: Phosphazene ("SPB-100" manufactured by Otsuka Chemical Co., Ltd., represented by the following structural formula (5))

  Phosphorus-modified phenoxy resin: Phosphorus-modified phenoxy resin (“ERF-001M30” manufactured by Toto Kasei Co., Ltd.), which is a mixed solvent of diglyme, xylene, methyl cellosolve, DMF, and toluene (mass mixing ratio 10: 5: 30: 30) 15) and the resin solid content was 30% by mass.

  Next, using a comma coater and a dryer connected thereto, the varnish obtained as described above is applied to one side of a copper foil having a thickness of 12 μm and dried, and the thickness after drying is 50 μm. A resin sheet with a copper foil was produced by forming a resin layer.

  And for each of the above varnishes, varnish storage stability was evaluated, and for each of the above resin sheets with copper foil, chemical resistance, copper foil peel strength, solder heat resistance (discoloration resistance), flexibility, circuit filling , Flame retardancy, migration resistance and bending discoloration were evaluated. The preparation conditions and evaluation conditions of the samples used for each of these evaluations are shown below, and the evaluation results are shown in [Table 1] below.

  (1) The varnish preservability was determined by measuring the initial viscosity and the viscosity after storage at 25 ° C. for 7 days, and “passing” a varnish whose viscosity change was less than 10%, “Fail”.

  (2) Chemical resistance was evaluated as follows. In other words, two resin sheets with copper foil were used, the surfaces on which these adhesive resin layers were formed were bonded together, and a sample was prepared by heating and pressing at 180 ° C. for 1 hour. The foil was removed by etching. Next, this sample was immersed in an aqueous solution of 3% by mass of sodium hydroxide and a temperature of 40 ° C. for 3 minutes and then taken out, washed with water, and sufficiently wiped off moisture with a dry clean cloth. Immediately thereafter, changes in appearance such as discoloration, swelling, and peeling of the sample were visually observed. And the thing without an external appearance change was set as "pass", and the thing with an external appearance change was set as "fail".

  (3) Copper foil peel strength is a sample obtained by laminating the surfaces on which the adhesive resin layer of the resin sheet with copper foil is formed on both surfaces of a polyimide film having a thickness of 25 μm, and heating and pressing at 180 ° C. for 1 hour. And the peel strength when the copper foil of this sample was peeled in the 90 ° direction was evaluated.

  (4) Solder heat resistance is a sample prepared by laminating a surface of an adhesive resin layer of a resin sheet with a copper foil on both sides of a polyimide film having a thickness of 25 μm, followed by heating and pressing at 180 ° C. for 1 hour. The film was immersed in a solder bath heated to 260 ° C. and 288 ° C. for 60 seconds, and then evaluated by observing the appearance. Those having no appearance abnormality such as blistering, peeling, and discoloration were determined as “pass”, and other cases were determined as “fail”.

  (5) Solder heat resistance of the copper foil etched product was obtained by bonding the surfaces of the polyimide film having a thickness of 25 μm on which the adhesive resin layer of the resin sheet with copper foil was formed, and heating and pressing at 180 ° C. for 1 hour. Further, a copper foil etched product was produced as a sample by removing the copper foil on both sides by etching, and this was evaluated by observing the appearance after being immersed in a solder bath heated to 260 ° C. for 30 seconds. Those having no appearance abnormality such as blistering, peeling, and discoloration were determined as “pass”, and other cases were determined as “fail”.

  (6) Flexibility is tested by the MIT method, and the measurement conditions are set to be R = 0.38 mm, the load is 500 g, and the rate is 175 times per minute. evaluated.

  (7) The circuit filling property is obtained by bonding the surface on which the adhesive resin layer of the resin sheet with copper foil is formed to a test piece formed by providing a comb-shaped pattern on a flexible printed wiring board of rolled copper foil having a thickness of 35 μm on one side. A sample was prepared by heating and pressing at 180 ° C. for 1 hour, and the appearance of this sample was evaluated by visual observation. The pattern filled with resin was regarded as “pass”, and the other pattern was defined as “fail”.

  (8) Flame retardancy was evaluated according to the flame retardancy criteria of 94 VTM according to UL94.

  (9) Migration resistance is obtained by bonding the surface on which the adhesive resin layer of the resin sheet with copper foil is formed to a test piece in which a comb-shaped electrode is provided on a single-sided flexible printed wiring board, and heating and pressing at 180 ° C. for 1 hour. A sample was prepared by molding, and the sample was evaluated by performing a test in which a voltage of 10 V was applied for 250 hours in an environment of 85 ° C./85% RH. And the migration degree after this test was evaluated visually. Those in which no migration occurred were defined as “pass”, and those other than this were defined as “fail”.

  (10) Bending discoloration was evaluated as follows. First, the surfaces on which the adhesive resin layer of the resin sheet with copper foil is formed are bonded to both sides of a polyimide film having a thickness of 25 μm, and heat-pressure molding is performed at 180 ° C. for 1 hour, and the copper foils on both sides are removed by etching. A sample was prepared. Next, after this sample was bent 180 °, the appearance of the mountain fold portion was observed. And the thing which does not generate | occur | produce appearance abnormality, such as whitening discoloration and a resin crack, was set as "pass", and the thing other than this was set as "fail".

  As seen in [Table 1] above, each of the examples has good varnish preservation and copper foil peel strength, high flexibility, and satisfactory flexibility required for flexible printed wiring boards and the like. It is confirmed that it is excellent in circuit filling properties. In addition, since no halogen-based flame retardant is used, it is a material with little toxic gas and fuming.

Claims (11)

  An epoxy resin composition for printed wiring boards, comprising (A) an epoxy resin, (B) an epoxy resin curing agent, (C) a carbodiimide-modified soluble polyamide, and (D) a dye as essential components.   2. The epoxy resin composition for a printed wiring board according to claim 1, wherein the content of the component (C) is 20 to 70% by mass with respect to the total amount of the components (A), (B), and (C). .   The epoxy resin composition for printed wiring boards according to claim 1 or 2, wherein an epoxy resin having a naphthalene skeleton is used as the component (A). The epoxy resin for printed wiring boards according to claim 3, wherein at least one of those represented by the following structural formulas (1) to (3) is used as an epoxy resin having a naphthalene skeleton. Composition.

5. The component according to claim 1, wherein at least one of an aminotriazine novolak resin represented by the following structural formula (4) and dicyandiamide is used as the component (B). Epoxy resin composition for printed wiring boards.

  The epoxy resin composition for printed wiring boards according to any one of claims 1 to 5, wherein a phenoxy resin is contained.   The epoxy resin composition for printed wiring boards according to any one of claims 1 to 6, wherein at least one of a phosphorus-modified epoxy resin, a phosphorus-modified phenoxy resin, and a phosphorus-based flame retardant is contained. object.   A resin film, wherein the epoxy resin composition for a printed wiring board according to any one of claims 1 to 7 is formed into a film shape.   A prepreg in which the epoxy resin composition for a printed wiring board according to any one of claims 1 to 7 is impregnated into a base material to be in a semi-cured state.   A resin sheet with a metal foil, wherein the epoxy resin composition for a printed wiring board according to any one of claims 1 to 7 is applied to a metal foil to be in a semi-cured state.   A flexible printed wiring board formed using at least one of the resin film according to claim 8, the prepreg according to claim 9, and the resin sheet with metal foil according to claim 10. .