JP2005068308A - Photoselective thermosetting resin composition sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a photoselective thermosetting resin composition sheet excellent in hole-plugging property, scarcely causing warping, excellent in storage stability and developing property and excellent in characteristics such as pressure cooker resistance, migration resistance and heat resistance and suitable for permanent protective film formation by one film-forming process. <P>SOLUTION: In a sheet integrated by applying a photoselective thermosetting resin composition using a resin as a permanent protective film by heat curing after carrying out selective curing of the resin by photoirradiation and removal of uncured part by dissolution to a mold-releasing sheet, the photoselective thermosetting resin composition having <50°C softening point is used and the composition is applied to one side of the mold release film and dried and a solvent is removed to prepare the photoselective thermosetting resin composition sheet and the sheets are arranged on the surface and the rear of a printed circuit board having a copper conductor circuit and these components are pressed by one process and light exposure, development and after-curing are carried out to form the permanent protective film. As a result, a thick film can be formed by one process and the permanent protective film scarcely causing warping, excellent in hole-plugging property, storage stability and developing property , excellent in characteristics such as heat resistance, migration resistance and adhesiveness and suitable for high-density printed circuit board is obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is arranged on the surface of a printed wiring board or the like on which a copper conductor circuit is formed, and is pressure-bonded by pressing, laminating or the like, then selectively cured with light, and after developing and removing uncured portions, The present invention relates to a photo-selective thermosetting resin composition sheet used for a permanent protective film obtained by post-curing, and a printed wiring board produced using the sheet is mainly used for a semiconductor plastic package as a high-density printed wiring board. It is preferably used for a motherboard.

  Conventionally, a thin film thermosetting paint by a screen printing method has been used as a permanent protective film for a printed wiring board. This thermosetting paint may cause bleed, resin sag, etc. during printing, and misalignment of the printed pattern. In recent years, it is used for high-density printed circuit boards that require increasingly precise positional accuracy and high resolution. Then it was not satisfactory. In order to cope with this, a photoselective thermosetting paint that can be developed with an aqueous solution to which an organic solvent is added or an alkaline aqueous solution has been developed. Specifically, a resin composition obtained by blending an aromatic epoxy compound with an unsaturated resin obtained by reacting a carboxyl group-containing acrylic resin with glycidyl (meth) acrylate, for example, a novolak type A resin composition obtained by adding a diluent to a compound obtained by reacting a reaction product of an epoxy resin and an unsaturated carboxylic acid with a saturated or unsaturated polybasic acid anhydride (see, for example, Patent Document 2), (meth) acrylic acid A cresol novolak type epoxy resin was blended with a resin obtained by reacting an alicyclic epoxy group-containing (meth) acrylate with a part of the carboxyl group of a vinyl copolymer having lactone-modified hydroxyl (meth) acrylate as an essential component. Resin compositions (see, for example, Patent Document 3) are known.

  In these light selective thermosetting paints, it is difficult to make the coating thickness of the front and back of the substrate the same, and there is a problem that warping after curing is likely to occur when applied to a thin plate. In addition, the screen printing method has irregularities on the surface of the coating film depending on the presence or absence of the conductor circuit on the surface, and it is difficult to form fine widths and holes by subsequent exposure and development. There was a drawback that it was difficult to form a coating film having a thickness of 40 μm or more by the work. Furthermore, since these paints usually use a solvent, there are concerns about deterioration of the working environment due to solvent odor and environmental pollution during drying. In addition, photo-selective thermosetting paints using these resin compositions are used as permanent protective coatings on the surface layers of printed wiring boards, which are becoming increasingly dense in recent years. It was not satisfactory enough in terms of sex.

Further, a polyfunctional cyanate ester and a photopolymerizable or photocrosslinkable monomer or a mixture of a prepolymer or a pre-reacted product is disclosed as a main component (for example, Patent Document 4). Development is not possible with dilute alkaline aqueous solution or aqueous solution with water-soluble organic solvent added, and there are problems such as partial dissolution of the photocured part when developed with a solvent. Use as a photoselective thermosetting paint. It was impossible.
Japanese Unexamined Patent Publication No. 1-139619 JP-A-61-243869 JP-A-8-41150 JP 56-141321 A

  The present invention provides a photoselective thermosetting resin composition sheet suitable for forming a permanent protective film on a high-density printed wiring board, which solves the above problems.

  The present invention uses a photoselective thermosetting resin composition having a softening point of less than 50 ° C., which is obtained by applying this to one side of a release film and drying to remove the solvent. It is a composition sheet, preferably, the thermosetting resin composition is a reaction of 5 to 35% by weight of epoxy resin (a), 100 parts by weight of epoxy acrylate and 5 to 40 parts by weight of a polyfunctional cyanate ester compound. An unsaturated group-containing polycarboxylic acid resin having an acid value of 40 to 200 mg KOH / g obtained by reacting the product with 10 to 90 parts by weight of a polybasic acid anhydride (hereinafter referred to as cyanate ester-based polycarboxylic acid resin). (b) 20 to 90% by weight, ethylenically unsaturated monomer (c) 1 to 30% by weight, photopolymerization initiator (d) A resin composition having 0.1 to 20% by weight as essential components, more preferably The photoselective thermosetting resin composition layer of the photoselective thermosetting resin composition sheet has a thickness of 5 to 100 μm A resin composition sheet. This photo-selective thermosetting resin composition sheet is disposed on both sides of a printed wiring board having a copper conductor circuit, and preferably bonded with a press machine, and then exposed, developed, and post-cured to form a permanent protective film. By doing so, it becomes easy to form fine wires and small-diameter holes, and it becomes a permanent protective film excellent in coating properties such as adhesion to the substrate and heat resistance. Also, by setting the softening point of the applied light selective thermosetting resin composition to less than 50 ° C, it is possible to embed copper conductors and fill the resin into the through-holes even at low temperatures. The time required for heating can be shortened and productivity can be improved.

  Since the light selective thermosetting resin composition sheet of the present invention does not contain a solvent at the time of use, it is gentle on the working environment, excellent in workability, can reduce the warpage of the printed wiring board, has almost no surface unevenness, and is through-through. Good hole filling performance. In particular, as a thermosetting resin composition, an unsaturated group-containing polycarboxylic acid resin in which a polyfunctional cyanate ester component is incorporated in the molecule is used, and light comprising an epoxy resin, an ethylenically unsaturated monomer, and a photopolymerization initiator. The selective thermosetting resin composition sheet has excellent storage stability and developability, and is suitable for a high-density printed wiring board excellent in adhesion to the printed wiring board, pressure cooker resistance, migration resistance, and heat resistance. A protective film can be obtained.

  The photoselective thermosetting resin composition used in the present invention is a resin composition that can be used as a permanent protective film by thermal curing after selective curing of the resin by light irradiation and dissolution and removal of the uncured part, The softening point is not particularly limited as long as it is less than 50 ° C. These photoselective thermosetting resin compositions include an epoxy resin, an unsaturated group-containing polycarboxylic acid resin, an ethylenically unsaturated monomer, and a photoselective heat having a softening point of less than 50 ° C. containing a photopolymerization initiator as essential components. A curable resin composition such as a photoselective thermosetting resin composition described in JP-A-1-39619, JP-A-61-243869, JP-A-8-41150, etc. has a softening point of 50. Those having a temperature of less than 0 ° C. can be used. Preferably, the reaction product of 5 to 35% by weight of epoxy resin (a), 100 parts by weight of epoxy acrylate and 5 to 40 parts by weight of a polyfunctional cyanate compound is used. Cyanate ester polycarboxylic acid resin (b) having an acid value of 40 to 200 mg KOH / g reacted with 10 to 90 parts by weight of a polybasic acid anhydride, ethylenically unsaturated monomer (c) 1 to 30 A photoselective thermosetting resin composition comprising, by weight, a photopolymerization initiator (d) 0.1 to 20% by weight as an essential component used.

  The epoxy resin (a) used in the photoselective thermosetting resin composition used in the present invention is not particularly limited as long as it is a compound having an epoxy group in one molecule. Specific examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, polyfunctional phenol type epoxy resin, halogenated bisphenol A type epoxy. Resin, halogenated phenol novolac type epoxy resin, phosphorus-containing epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, polyol type epoxy resin, alicyclic epoxy resin; polyepoxy compound with epoxidized double bond such as butadiene, Examples thereof include polyglycidyl compounds obtained by the reaction of hydroxyl group-containing silicone resins and epichlorohydrin. One or two or more kinds can be used as appropriate. The amount of the epoxy resin (a) used is 5 to 35% by weight, preferably 10 to 25% by weight.

  The cyanate ester-based polycarboxylic acid resin (b) used in the photoselective thermosetting resin composition used in the present invention is preferably a polyfunctional cyanate ester compound 5 to 100 parts by weight of epoxy acrylate. Cyanate ester polycarboxylic acid having an acid value of 40 to 200 mg KOH / g, more preferably an acid value of 50 to 160 mg KOH / g, obtained by reacting 40 parts by weight of a resin with 10 to 90 parts by weight of a polybasic acid anhydride Acid resin. As a permanent protective film for high-density printed wiring boards, heat resistance, migration resistance, etc. are problematic. Therefore, cyanate ester-based polycarboxylic acids incorporating polyfunctional cyanate compounds with excellent properties in these molecules. Acid resins are preferred. The amount of the cyanate ester polycarboxylic acid resin (b) used is 10 to 90% by weight, preferably 20 to 70% by weight.

  The polyfunctional cyanate ester compound used in the cyanate ester-based polycarboxylic acid resin (b) is not particularly limited as long as it is a compound having two or more cyanate groups in one molecule. Specific examples thereof include 1,3- or 1,4-dicyanate benzene, 1,3,5-tricyanate benzene, 1,3-, 1,4-, 1,6-, 1,8-, 2 , 6- or 2,7-dicyanate naphthalene, 1,3,6-tricyanate naphthalene, 4,4'-dicyanate biphenyl, bis (4-dicyanatephenyl) methane, 2,2-bis (4-cyanate) Phenyl) propane, 4,4′-methylenebis (2,6 dimethylphenyl cyanate), bis (4-cyanatephenyl) ether, bis (4-cyanatephenyl) thioether, bis (4-cyanatephenyl) sulfone, tris (4- Cyanate phenyl) phosphite, tris (4-cyanate phenyl) phosphate, tetramethylbiphenyl cyanate, hexamethylbiphenyl cyanate; novolak, phosphorus-containing novolak, hydroxyl-containing thermoplastic oligomer (eg hydroxypolyphenylene ether) And cyanates obtained by the reaction of cyanide and the like, and one kind or two or more kinds can be appropriately mixed and used.

  A prepolymer having a weight average molecular weight of 400 to 6000 having a triazine ring formed by trimerization of cyanate groups of these cyanate ester compounds is preferably used. As a prepolymer production method, the above-mentioned cyanate ester monomers are polymerized using, for example, acids such as mineral acids and Lewis acids; salts of tertiary amines such as sodium alcoholate, salts such as sodium carbonate and the like as catalysts. Is obtained. This prepolymer also includes a partially unreacted monomer, which is in the form of a mixture of the monomer and the prepolymer, and such a raw material is suitably used for the application of the present invention.

  The epoxy acrylate used for the cyanate ester-based polycarboxylic acid resin (b) is not particularly limited as long as it is a reaction product of an epoxy resin and acrylic acid. Specific examples thereof include bisphenol A type epoxy acrylate, bisphenol F type epoxy acrylate, biphenol / epoxy acrylate, tetramethyl biphenol / epoxy acrylate, hexamethyl biphenol / epoxy acrylate, xylene novolac / epoxy acrylate, etc. Two or more kinds can be appropriately mixed and used.

  The polybasic acid anhydride used in the cyanate ester-based polycarboxylic acid resin (b) is not particularly limited as long as it is a compound having two or more carboxylic anhydrides in one molecule. Specific examples include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, benzophenone tetracarboxylic anhydride, tetrahydrophthalic anhydride, hexahydro anhydride Examples thereof include phthalic acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, succinic anhydride, dodecenyl succinic anhydride, and the like. It is.

  The blending ratio when the epoxy acrylate and the polyfunctional cyanate ester compound are reacted is 5 to 40 parts by weight, preferably 10 to 30 parts by weight with respect to 100 parts by weight of the epoxy acrylate. . Although reaction conditions are not specifically limited, For example, reaction temperature is 50-100 degreeC, reaction time is 5-100 hours, and it is also possible to use a solvent for viscosity adjustment at the time of reaction. Although the solvent to be used is not particularly limited, for example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; dipropylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, etc. Acetates; aromatic hydrocarbons such as solvent naphtha, toluene, and xylene can be used alone or in combination of two or more.

  When the polybasic acid anhydride is reacted with the reaction product of the epoxy acrylate and the polyfunctional cyanate compound, the blending ratio is 100 parts by weight of the epoxy acrylate and 5 to 40 parts by weight of the polyfunctional cyanate compound. The polybasic acid anhydride is 10 to 90 parts by weight based on the reaction product. From the viewpoint of developability, the polybasic acid anhydride is preferably used at a rate such that the resin acid value after the reaction is 50 to 160 mgKOH / g. Mix the ingredients. Although reaction conditions are not specifically limited, For example, reaction temperature is 50-100 degreeC and reaction time is 3-100 hours. The obtained resin has an acid value of 40 to 200 mgKOH / g, preferably 50 to 160 mgKOH / g. Also in this case, it is possible to use a solvent for viscosity adjustment. Specifically, the above solvents and esters such as propylene glycol monomethyl ether and dipropylene glycol monomethyl ether are used.

  The photoselective thermosetting resin composition used in the present invention includes a known unsaturated group-containing polycarboxylic acid resin in addition to the cyanate ester-based polycarboxylic acid resin (b). It can be added as long as the properties of the composition are not impaired. These unsaturated group-containing polycarboxylic acid resins are not particularly limited. For example, as shown in JP-A 1-139619, unsaturated groups obtained by reacting a carboxyl group-containing acrylic resin and glycidyl (meth) acrylate. -Containing resin, alicyclic epoxy group-containing unsaturation in a part of the carboxyl group of the vinyl copolymer containing (meth) acrylic acid and lactone-modified hydroxyalkyl (meth) acrylate described in JP-A-8-41150 as essential components Unsaturated group-containing resin obtained by reacting a compound, obtained by reacting a reaction product of a novolak epoxy compound and an unsaturated monocarboxylic acid described in JP-A-61-243869 with a saturated or unsaturated polybasic acid anhydride Resin, acid value 10-200mgKOH / g, (meth) acrylic acid and lactone-modified hydroxyalkyl having 1.0-3.5 mol double bond per kg of resin and 1,000-50,000 number average molecular weight Unsaturated group-containing resin, phenol novolak type, cresol novolak type, or halogenation thereof obtained by reacting a carboxyl group-containing (meth) acrylic resin having (meth) acrylate as an essential component with an alicyclic epoxy group-containing unsaturated compound An epoxy resin and an unsaturated carboxylic acid are reacted in a ratio of acid equivalent / epoxy equivalent in the range of 0.2 to 1.0, and a saturated or unsaturated polybasic acid anhydride is converted to acid equivalent / hydroxyl equivalent of the hydroxyl group of the obtained reaction product. And a unsaturated group-containing resin having an acid value of 40 to 160 mgKOH / g.

  Examples of the ethylenically unsaturated monomer (c) used in the photoselective thermosetting resin composition used in the present invention include (meth) acrylic acid esters of dihydric or higher alcohols. Examples of the alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, hexanediol, heptanediol, neopentyl glycol, 1 , 10-decanediol, cycloheptanediol, 1,4-cyclohexanedimethanol, etc .; polyethylene glycols such as diethylene glycol and triethylene glycol; polypropylene glycols such as dipropylene glycol and tripropylene glycol; xylenediol, 2-ethyl- 1,3-hexanediol, biphenol, catechol, resorcinol, pyrogallol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol , Sorbitol, glucose, butane triol, 1,2,6-trihydroxy hexane, 1,2,4-benzene triol. Further, for example, polyallyl esters such as adipic acid, phthalic acid, terephthalic acid, trimellitic acid, polyallyl esters of polysulfonic acid, diallyl ether, triallyl isocyanurate, and the like can be used. Polyvinyl compounds such as divinyl sulfone, divinyl phthalate and divinyl terephthalate can also be used. These compounds can be used alone or in combination of two or more. The amount of the ethylenically unsaturated monomer (c) used is 1 to 30% by weight, preferably 2 to 20% by weight.

  In the photoselective thermosetting resin composition used in the present invention, a photopolymerization initiator (d) is used for polymerization with light. Examples of the photopolymerization initiator (d) include α-diketones such as benzyl and diacetyl; acyloins such as benzoyl; acyloin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; Thioxanthones such as thioxanthone and 1,4-diethylthioxanthone; Benzophenones such as benzophenone and 4,4'-bis (dimethylamino) benzophenone; Acetophenone, 1,2'-dimethoxy-2-phenylacetophenone, p-methoxyacetophenone, etc. Acetophenones; quinones such as anthraquinone and 1,4-naphthoquinone; peroxides such as di-t-butyl peroxide and the like. The amount of the photopolymerization initiator (d) used is 0.1 to 20% by weight, preferably 0.2 to 10% by weight.

In addition, when an oxetane resin or an alicyclic epoxy resin that reacts with a cationic photopolymerization initiator is blended, for example, an aromatic sulfonium salt, η ⁵ -2,4-cyclopentadien-1-yl) [(1 , 2,3,4,5,6-η)-(1-methylethyl) benzene] -iron (1 +)-hexafluorophosphate (1-) and other cationic photopolymerization initiators such as iron complexes It is preferable to add 1 type or 2 types or more appropriately. The cationic photopolymerization initiator is used in an amount of 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, based on 100 parts by weight of the resin reacted with the cationic polymerization initiator.

  If necessary, an epoxy resin curing accelerator may be added to the photoselective thermosetting resin composition used in the present invention for the purpose of accelerating curing during thermosetting. Although this hardening accelerator is not specifically limited, A thing with low activity is preferable at 50 degrees C or less. More preferably, in order to maintain good storage stability of the photoselective thermosetting resin composition, a curing accelerator having a melting point of 100 ° C. or higher and a solubility in the photoselective thermosetting resin composition of 10% by weight or less. (e) is blended in an amount of 0.01 to 10% by weight. This is a fine powder, preferably a powder of 5 μm or less, which is uniformly dispersed in the photoselective thermosetting resin composition. Examples of these curing accelerators (e) include 2-heptadecylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4- Examples include benzyl-5-hydroxymethylimidazole, 2,4-diamino-6- {2-methylimidazolyl- (1)}-ethyl-S-triazine, and the like. One or two or more are used as appropriate. .

  For the purpose of crosslinking the epoxy resin of the photoselective thermosetting resin composition used in the present invention, a curing agent may be used. The photo-selective thermosetting resin composition is post-cured after development. In order to improve storage stability, the reactivity is slow at low temperatures, and it can be cured at a high temperature, typically 150 ° C for about 1 hour. In order to cure the epoxy resin, it is preferable to use a latent curing agent. The latent curing agent is not particularly limited, and generally known ones can be used, but more preferably, the melting point is 100 ° C. or more and the solubility in the photoselective thermosetting resin composition is 10% by weight or less. Is used. These are curing agents that exhibit reaction activity by melting, decomposing, elution, ionic reaction, or breaking the wall when heated to 100 ° C or higher, and have low activity at temperatures below the melting point. It becomes the light selective thermosetting resin composition which is excellent in. These latent curing agents are not particularly limited. Specifically, dicyandiamide, organic acid hydrazide, diaminomaleonitrile, melamine and derivatives thereof, polyamine salts, and the like can be used, but amine adduct type curing agents are preferable. .

  The amine adduct type curing agent is a prepolymer type curing agent having an active hydrogen site and a catalytic function site in the molecule, and is an adduct of an amine compound and an epoxy resin, preferably having a melting point of 100 ° C. or higher. Specific examples include Amicure PN-23, MY-24, PN-D, MY-D, PN-H, and MY-H, which are products of Ajinomoto Co., Inc. Used. These are used as a powder, preferably a powder having a particle size of 5 μm or less, dispersed in the photoselective thermosetting resin composition. The amount of the latent curing agent used is 0.1 to 10% by weight, preferably 0.2 to 8% by weight.

  The photoselective thermosetting resin composition used in the present invention is a homogeneous solvent-free type by combining the components, or the photoselective thermosetting resin composition mainly composed of solid content is dissolved in a solvent or It is used as a solution type formulated by suspending. It is preferable that the other resin compositions excluding the latent curing agent and the curing accelerator are preliminarily dissolved in a dissolving solvent and blended. Solvent to be dissolved is not particularly limited. For example, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ethyl acetate, isobutyl acetate, n-butyl acetate, ethylene glycol monoacetate, propylene glycol acetate, dipropylene glycol monoacetate And esters such as carbitol acetate, aromatic hydrocarbons such as toluene and xylene, ethylene glycol alkyl ethers, diethylene glycol alkyl ethers, propylene glycol alkyl ethers, and dipropylene glycol alkyl ethers. These are used alone or in combination of two or more.

  In the photoselective thermosetting resin composition used in the present invention, various additives can be blended as desired within a range that does not impair the original characteristics of the composition. These additives include polyfunctional maleimides, polybutadiene, maleated butadiene, butadiene-acrylonitrile copolymer, butadiene-styrene copolymer, acrylic rubber, multilayer rubber powder, AS resin, ABS resin, MBS resin. , Unsaturated group-containing PPE resin, polyphenylene ether, polysulfone, polyester, polyphenylene sulfide, polystyrene, polyurethane and the like. In addition, other known organic fillers, inorganic fillers, dyes, pigments, thickeners, lubricants, antifoaming agents, dispersants, leveling agents, photosensitizers, thixotropic agents, flame retardants, etc. Various additives are used in appropriate combinations as desired. If necessary, the compound having a reactive group is appropriately added with a curing agent and a catalyst that do not impair characteristics such as storage stability.

  The sheet to which the solution of the photoselective thermosetting resin composition used in the present invention is applied is not particularly limited, and preferably includes a thermoplastic film having a thickness of 25 to 50 μm, a metal foil, and the like. As the thermoplastic film, for example, a polyethylene terephthalate film, a polybutylene terephthalate film, a polypropylene film, a polyvinyl chloride film, and a multilayer film thereof are used. The surface of the film can be used without any treatment or with a known mold release treatment, but one having aluminum deposited on one surface to block light is preferably used. As the metal foil, an aluminum foil, a copper foil, a nickel foil, or the like can be used.

  The photoselective thermosetting resin composition used in the present invention can be used either without a solvent or dissolved in a solvent. However, in order to control the thickness at the time of application, a composition with a solvent is preferably used. used. This resin composition solution is applied onto a release film and dried to a predetermined thickness. Even if some solvent remains in the resin composition layer, it can be used as long as it does not affect the subsequent processing. As a coating method, a known method such as a roll coater, a bar coater, or a gravure coater is applied to one side of a thermoplastic film or a metal foil, followed by drying to obtain a photoselective thermosetting resin composition sheet. If there is tack, it can be wound as it is, but if it is tacked, it can be wound as it is, but a protective film such as polypropylene film is preferably applied to the opposite side and integrated while laminating. Wind up. The thickness of the resin composition layer of the photoselective thermosetting resin composition sheet is not particularly limited, but is preferably 5 to 100 μm, more preferably 20 to 70 μm.

  The photoselective thermosetting resin composition sheet of the present invention is placed on a printed wiring board having a copper conductor circuit, and is heated, pressurized, or vacuumed as necessary using a known apparatus such as a laminating or pressing apparatus. After being pressure-bonded and bonded to the printed wiring board, the resin is selectively cured by light irradiation, the uncured portion is dissolved and removed, and then becomes a permanent protective film by heat curing. When forming fine lines or holes, it is preferable that the surface has less irregularities, and press bonding is more preferable than laminating. The laminating or pressing temperature is not particularly limited, and is generally 20 to 250 ° C, preferably 20 to 150 ° C. The crimping time is not particularly limited, and is generally 1 to 60 minutes, preferably 1 to 30 minutes. If the pressure bonding time is long, curing of the resin proceeds, and there is a possibility that a resin residue may be generated in the subsequent development, and the temperature and time are appropriately selected depending on the resin composition. There is no particular limitation on the degree of vacuum, and the degree of vacuum that does not create a gap during crimping is selected, but it is generally 30 mmHg or less.

  After pressure bonding, a negative film is placed on this, and an active energy ray such as ultraviolet rays is irradiated to selectively photocure the necessary part, and then the uncured part is developed and removed with a dilute alkaline aqueous solution and then heated. After curing. Thereafter, electroless nickel plating, gold plating or the like is performed to obtain a printed wiring board. The printed wiring board can be used only by polishing the patterned copper conductor surface before the light selective thermosetting resin composition sheet is pressure-bonded, but a copper chelating agent or the like is preferably blended in advance. Process with anti-rust treatment. By performing the treatment, it is possible to improve the adhesion between the copper conductor and the resin for the coating, and to expect the effects that the insulation deterioration after the pressure cooker treatment is reduced and the peeling can be suppressed.

  As the rust preventive agent, generally known ones can be used. As the copper chelating agent, generally known ones are used, and examples thereof include polybenzimidazole and chromate treatment, and one or two or more are used as appropriate. For example, a rust preventive treatment (MEC treatment) such as CL8300E manufactured by MEC Co., Ltd. is preferably used. More preferably, the surface of the copper conductor is roughened using CZ8100 manufactured by MEC Co., Ltd. and then subjected to rust prevention treatment. By roughening the copper conductor surface, the adhesion can be further enhanced by the anchor effect between the copper conductor and the resin.

As an active energy ray irradiation light source for photocuring the photoselective thermosetting resin composition of the present invention, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a xenon lamp, a metal halide lamp, or the like is used. It is not particularly limited exposure generally 100~3,000mJ / cm ^2, preferably 300~2,000mJ / cm ^2. In addition, an electron beam, a laser, etc. can be used.

  Development of the photoselective thermosetting resin composition of the present invention is carried out by a known method such as a spray development method or a dip development method in which a printed wiring board is immersed in a developer and vibrated. The temperature of the developer is 5 to 50 ° C, preferably 25 to 40 ° C. If the temperature is low, problems such as long development time and poor developability occur. If the temperature is high, the cured portion irradiated with light will dissolve. As the developer, a known dilute alkaline aqueous solution such as an aqueous solution of sodium carbonate, sodium hydroxide or ammonium hydroxide can be used. Moreover, the aqueous solution which added the water-soluble organic solvent to water can be used. Moreover, the aqueous solution which added the water-soluble organic solvent to water and the aqueous solution which added the water-soluble organic solvent and the alkaline agent to water can also be used. The amount of the alkaline agent in the aqueous solution is preferably 0.1 to 5% by weight.

  Water-soluble organic solvents include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, methyl lactate, ethyl lactate, butyl lactate, diethylene glycol, methanol, ethanol, propanol, γ -Well-known things, such as butyrolactone and methyl cellosolve, can be used. These solvents are used in the range of 10 to 80% by weight, preferably 15 to 50% by weight of the total aqueous solution. Furthermore, an alkali agent such as sodium hydroxide, sodium silicate, monomethanolamine or the like can be added to improve developability.

  The photoselective thermosetting resin composition of the present invention is heat-cured after development. The curing temperature is 100 to 200 ° C, preferably 120 to 170 ° C. Thereafter, nickel plating and gold plating are performed.

Synthesis examples, examples, and comparative examples are shown below to specifically explain the present invention. "Parts" represents parts by weight.

Synthesis Example 1 <Synthesis of polyfunctional cyanate ester prepolymer>
1,000 parts of 2,2-bis (4-cyanatephenyl) propane was melted at 150 ° C. and reacted for 4 hours with stirring to obtain a prepolymer (X-1) having a weight average molecular weight of 1,900 and a softening point of 66 ° C. . This was dissolved in methyl ethyl ketone to prepare a solution.

Synthesis Example 2 <Synthesis of cyanate ester-based polycarboxylic acid resin>
A flask was equipped with a thermometer, stirrer, reflux condenser, dropping funnel and nitrogen blowing tube, and 1,000 parts of bisphenol A type epoxy acrylate (SP1509, Showa High Polymer Co., Ltd.), polyfunctional cyanate ester prepolymer ( Charge 50 parts by weight of X-1) and 1,050 parts of dipropylene glycol monomethyl ether acetate / solvent naphtha (50/50 weight ratio) as a solvent to give a solid content of 50% by weight. The change of the peak of cyanate group (around 2300 cm-1) was followed by infrared absorption spectrum. The reaction was terminated when the peak of the cyanate group disappeared after 5.5 hours. To this reaction solution, 218 parts of pyromellitic anhydride and 218 parts of the above mixed solvent were added, and the reaction was conducted while stirring and mixing at a temperature of 70 ° C. The peak of carboxylic anhydride (around 1,850 cm-1 was observed by infrared absorption spectrum). ), And the reaction was terminated when the peak disappeared after 6 hours. The acid value of this cyanate ester-based polycarboxylic acid resin (solid component: B-1) was 90 mgKOH / g.

Synthesis example 3
In Synthesis Example 2, the amount of the polyfunctional cyanate ester prepolymer (X-1) used was changed from 50 parts to 300 parts, and tetrahydrophthalic anhydride was added as an acid anhydride instead of 218 parts of pyromellitic anhydride. A cyanate ester-based polycarboxylic acid resin (solid component: B-2) was prepared in the same manner as in Synthesis Example 2 except that a part thereof was added. The acid value of this resin was 100 mgKOH / g.

Synthesis example 4
The same as Synthesis Example 2 except that the amount of polyfunctional cyanate ester prepolymer (X-1) used in Synthesis Example 2 was changed from 50 parts to 100 parts and pyromellitic anhydride was used from 218 parts to 174 parts. Similarly, cyanate ester-based polycarboxylic resin (solid component: B-3) was prepared. The acid value of this resin was 75 mgKOH / g.

Synthesis example 5
A flask was equipped with a thermometer, stirrer, reflux condenser, dropping funnel and nitrogen blowing tube. To this was charged 1,000 parts of dipropylene glycol monomethyl ether and heated to 100 ° C, while 14 parts of benzoyl peroxide, 420 parts of methyl methacrylate. Then, a mixture of 70 parts of hydroxyethyl methacrylate and 210 parts of methacrylic acid was dropped over 2 hours and held for 8 hours. The obtained acrylic resin had an acid value of 200 mgKOH / g. Next, 210 parts of glycidyl methacrylate, 3.5 parts of triethylamine, and 0.07 part of hydroquinone were added to this resin, and reacted at 100 ° C. for 5 hours to obtain an unsaturated group-containing polycarboxylic acid resin having a methacryloyl group of 1.7 mol / kg and an acid value of 89 mgKOH / g ( Solid component: B-4) A solution was obtained.

Examples 1-4
Each component was mix | blended with the compounding ratio shown in Table 1, and it knead | mixed with 3 rolls, and obtained the viscous photoselective thermosetting resin composition. These photoselective thermosetting resin compositions are continuously applied to one side of a 25 μm thick polyethylene terephthalate (PET) film and dried to create a photoselective thermosetting resin composition sheet having a thickness of 15 to 60 μm. Then, at the stage of coming out from the drying zone, the resin composition side of the photoselective thermosetting resin composition sheet and the film side of the 25 μm thick polyethylene film deposited on one side are opposed to each other at 60 ° C., 5 kgf After laminating and laminating continuously at a linear pressure of / cm and winding up continuously, this was cut into a workpiece size. Comb circuit (used copper-clad laminate: CCL-HL830 18μm copper foil on both sides, insulation layer thickness 0.4mm, manufactured by Mitsubishi Gas Chemical Co., Ltd., line / space: 70 / 70μm) is formed from these sheets. 400 through-holes of 200μm were made on a 50x50mm board, and the copper conductor circuit surface was processed by MEC treatment (MEC Co., Ltd.) with copper foil surface unevenness treated by 1μm and rust-proof printed wiring board J. 5 μm thick copper foil is bonded to both sides of a 50 μm thick polyimide film, and aluminum of the above-mentioned photoselective thermosetting resin composition sheet is formed on both sides of a printed wiring board K having 400 through holes with a hole diameter of 200 μm within 50 × 50 mm. Place the deposited polyethylene film so that the resin layer faces the printed wiring board, place a 1mm thick stainless steel plate on the outside, and press for 20 minutes under a vacuum of 10kgf / cm ² and 5mmHg. Crimp to form a smooth surface and at the same time It was filled with all of the Le. With the PET film as it is, a negative film is adhered to the surface, exposed to 700 mJ / cm ² of ultraviolet light, exposed to light, developed with a dilute alkaline aqueous solution, and further cured at 150 ° C. for 60 minutes to obtain a permanent surface. The protective film was cured. The measurement results are shown in Table 2.

Comparative Examples 1-3
The coating solution obtained with the blending ratio shown in Table 1 was applied on the printed wiring board J one side at a time by a screen printing method and dried to obtain a permanent protective film. In this case, the thickness of the film could be applied only 20-35 μm at a time, and the process was repeated twice each for the surface thickness to be 40 μm or more. Thereafter, a negative film was applied in the same manner, followed by exposure, development, and post-curing. The measurement results are shown in Table 2.

Comparative Example 4
Using the coating solution obtained with the blending ratio in Table 1, a photoselective thermosetting resin composition sheet having a thickness of 15 μm was prepared in the same manner as in the Examples, and was placed on both sides of the printed wiring board K. A stainless steel plate with a smooth surface and a thickness of 1 mm was placed, and press-pressed for 20 minutes under a vacuum of 25 ° C., 10 kgf / cm ² , 5 mmHg to form a film with a smooth surface, and at the same time, all the through holes were filled. With the PET film as it is, a negative film is adhered to the surface, exposed to 700 mJ / cm ² of ultraviolet light, exposed to light, developed with a dilute alkaline aqueous solution, and further cured at 150 ° C. for 60 minutes to obtain a permanent surface. The protective film was cured. The measurement results are shown in Table 2.

Table 1
Example Comparison example
Component 1 2 3 4 1 2 3 4
(a) A-1 7 12 − 7 7 12 − 12
A-2 3 − 5 5 3 − 5 −
A-3 − 3 17 10 − 3 17 3
(b) B-1 65 − − 30 − − − −
B-2 − 60 − 35 − 60 − 60
B-3 − − 70 − − − 70 −
B-4 − − − − 66 − − −
(c) C-1 10 3 − 5 10 8 − 3
C-2 − 7 12 5 − − 12 −
(d) D-1 10 10 12 12 10 10 12 10
(e) E-1 7 3 4 − − − − 3
E-2 − − − − 5 − 6 −
(f) F-1 − − − − 2 4 − −
F-2 0 4 4 4 − − − 4
(g) G-1 0.3 − 0.3 − 0.3 − 0.3 0.3
G-2 0.3 − 0.3 − 0.3 − 0.3 0.3
G-3 − 0.5 − 0.5 − 0.5 − −
(h) H-1 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
H-2 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
H-3 2 2 2 2 2 2 2 2
(i) I-1 15 15 15 15 15 15 15 15
I-2 15 15 15 15 15 15 15 15

A-1: Modified xylene resin epoxidized product (Denacar T, manufactured by Nagase Kasei Co., Ltd.)
A-2: Alicyclic epoxy resin (Celoxide 2021, manufactured by Daicel Chemical Industries, Ltd.)
A-3: Polyfunctional alicyclic epoxy resin (EHPE3150, manufactured by Daicel Chemical Industries, Ltd.)
C-1: Tetraethylene glycol diacrylate
C-2: Trimethylolpropane triacrylate
D-1: Photopolymerization initiator (Irgacure 907, Ciba Geigy Co., Ltd.)
E-1: Amine Adduct MY-24 (Slightly soluble in the solvent used; 5 wt% or less, Melting point: 120 ° C, manufactured by Ajinomoto Co., Inc.)
E-2: Triethylenediamine (soluble in the solvent used, melting point: liquid at 50 ° C or lower)
F-1: 2-ethyl-4-methylimidazole (soluble in the solvent used, melting point: 41 ° C)
F-2: 2-Phenyl-4,5-dihydroxymethylimidazole (slightly soluble in the solvent used, melting point 220 ° C)
G-1: Blue pigment (copper phthalocyanine blue, CI Pigment Blue 15: 3)
G-2: Yellow pigment (CIPigment Yellow 151)
G-3: Green pigment (CIPigment Green 7)
H-1: Leveling agent (BYK055, manufactured by Big Chemie Japan Co., Ltd.)
H-2: Defoaming agent (Floren AC300, manufactured by Kyoeisha Chemical Co., Ltd.),
H-3: Coupling agent (A-187, manufactured by Nihon Unica Co., Ltd.)
I-1: Barium sulfate
I-2: Synthetic silica

Table 2
Example Comparison example
Item 1 2 3 4 1 2 3 4

Film sheet softening point 42 ℃ 40 ℃ 38 ℃ 22 ℃ ー ー ー 58 ℃

Storage stability (hrs) 24 <24 <24 <24 <<10 <15 <15 24 <

Wiring board type JJJKJJJK

Press temperature 80 ℃ 80 ℃ 45 ℃ 25 ℃ ー ー ー 25 ℃

Resin flow (mm) 1.0 1.7 0.7 <0.1 ー ー ー <0.1

Developability Good Good Good Good Good Bad Bad Bad Good

Acid resistance Good Good Good Good Good Good Whitening Good

Film thickness (μm) 50 60 40 15 50 60 40 15

Thickness variation (μm) <± 3 <± 3 <± 3 <± 2 ± 9 ± 7 ± 10 ± 10

Surface irregularities (μm) <3 <3 <3 <1 19 21 21 18

Pencil hardness 4H 4H 5H 5H 4H 4H 4H 5H

Adhesion (Y / 100)
* 1) 100/100/100/100/100/100/100/100 /
* 2) 99/100/100/100/64/45/27/70 /
* 3) 99/100/100/100/77/63/41/80 /

Fillability (n / 400) 0/0/0/0/241/270/177/130

Solder heat resistance Good Good Good Good Swelling Swelling Swelling Good

Migration resistance (Ω)
Normal 4x10 ¹⁴ 3x10 ¹⁴ 3x10 ¹⁴ 4x10 ¹⁴ 3x10 ¹⁴ 5x10 ¹⁴ 3x10 ¹⁴ 4x10 ¹⁴
500hrs. 7x10 ¹⁰ 4x10 ¹⁰ 3x10 ¹⁰ 8x10 ¹⁰ 1x10 ⁸ 4x10 ⁹ 3X10 ⁹ 8x10 ⁹
Insulation resistance (Ω)
200hrs. 5x10 ¹⁰ 3x10 ¹⁰ 2x10 ¹⁰ 6x10 ¹⁰ <10 ⁸ <10 ⁸ <10 ⁸ 2x10 ¹⁰
Warpage (mm) <4 <4 <2 <2 17 20 16 <2

* 1) Measurement without moisture absorption.
* 2) Measurement after pressure cooker (121 ℃, 203kPa, 100 hours) treatment.
* 3) Measurement after gold plating.

<Measurement method>
Film sheet softening point: Measured by dry bulb method according to JIS K 7234.

Storage stability: Each component is uniformly mixed and then stored at a temperature of 25 ° C. Judged by the presence or absence of a residue after 60 seconds of development time.

Resin flow: The maximum value of the resin flow when the light selective thermosetting resin composition sheet is pressed.

Developability and acid resistance: While visually observing the development surface, electroless nickel plating (PH 4.5, immersion 90 ° C / 20 minutes) was applied, and the adhesion state of nickel plating was observed. . At the same time, observe the state of the film surface being attacked by chemicals, and determine whether there is any abnormality such as discoloration or dissolution.

Thickness variation: Measure the thickness of the film on the front and back of the cross section and calculate the difference.

Surface roughness: The surface roughness of the film on the printed wiring board is measured with a surface roughness meter.

Pencil hardness: Measured according to JIS K 5400.

Adhesion: In accordance with JIS K 5400, 100 100 mm 1 mm grids were made on the test piece, peeled off with cello tape, and the peeled state of the grids was measured. (The denominator in the table is the number of test grids, the numerator is the remaining number)

Cavity filling: Measurement of air bubbles in the cuff filling from a cross-section photo. (In the table, the denominator is the number of holes, the numerator is the number of holes containing bubbles)

Solder heat resistance: After immersing the test piece in a solder bath at 260 ° C for 30 seconds, visually check for abnormalities in the coating film.

Migration resistance: Using a comb circuit of line / space = 70 / 70μm, after forming and curing a permanent protective film, perform migration test by applying 85 ℃, 85% RH, 50VDC and measure insulation resistance did.

Insulation resistance: Using the above test piece, after processing for 200 hours at 121 ° C and 2kgf / cm ² , leave it in an atmosphere of 25 ° C and 60% RH for 90 minutes, and then apply 500VDC for 60 seconds to determine the insulation resistance value. Measurement. (n = 4)

Warpage: The outer layer copper foil of a double-sided copper clad laminate with a thickness of 0.1 mm is etched, a protective film is formed on both sides, and a sample cut to a size of 250 x 250 mm is used. Was measured.

Claims (3)

After selective curing of the resin by light irradiation and dissolution and removal of the uncured part, it is applied to the integrated sheet by applying the photoselective thermosetting resin composition to be used as a permanent protective film by thermosetting to the release sheet. Photoselective thermosetting resin composition sheet having a softening point of less than 50 ° C. The photoselective thermosetting resin composition comprises a polybasic acid in a reaction product of 5 to 35% by weight of epoxy resin (a), 100 parts by weight of epoxy acrylate and 5 to 40 parts by weight of a polyfunctional cyanate compound. An unsaturated group-containing polycarboxylic acid resin having an acid value of 40 to 200 mg KOH / g reacted with 10 to 90 parts by weight of anhydride (b) 20 to 90% by weight, ethylenically unsaturated monomer (c) 1 to 30% by weight, 2. The photoselective thermosetting resin composition sheet according to claim 1, wherein the photoselective thermosetting resin composition comprises 0.1 to 20% by weight of a photopolymerization initiator (d) as an essential component. The photoselective thermosetting resin composition sheet according to claim 1 or 2, wherein the thickness of the resin composition layer of the photoselective thermosetting resin composition sheet is 5 to 100 µm.