Alkaline-developable resin composition, its photocurable dry film and its cured product, and printed circuit board formed using the same

Abstract

The present invention provides an alkaline-developable resin composition having good printability (covering property, sagging) and stability (tin plating resistance, boiling water whitening resistance), an alkaline-developable resin composition capable of forming a solder resist film excellent in thermal shock resistance and high-temperature storage stability, a photocurable dry film thereof and a cured product thereof, and a printed circuit board formed using the same. The alkaline-developable resin composition is characterized by containing (A) a vinyl ester resin, (B) a photopolymerization initiator, (C) an antioxidant, (D) a compound having two or more ethylenically unsaturated groups in one molecule, and (E) an inorganic filler, wherein the (E) inorganic filler contains talc, and the content of the talc is 50% by weight or more based on 100% by weight of the total amount of the (E) inorganic filler, and the total content of the (E) inorganic filler is 60 to 180 parts by weight based on 100 parts by weight of the (A) vinyl ester resin.

Description

Technical Field

[0001] The present invention relates to an alkali-developable resin composition applicable to the formation of solder masks, etc. of printed circuit boards, a photocurable dry film thereof, and a cured product thereof, and particularly relates to an alkali-developable resin composition capable of forming a solder mask having excellent thermal shock resistance with good printability, a photocurable dry film thereof, a cured product thereof, and a printed circuit board. Background Art

[0002] Currently, in the formation of solder masks (solder resist layers) of some consumer printed circuit boards and almost all industrial printed circuit boards, an alkali-developable solder resist that forms an image by developing after ultraviolet exposure and is completely cured (main curing) by heat and / or light irradiation is used. In addition, in semiconductor devices for transportation means such as automobiles, trains, ships, and airplanes and communication equipment for special environments, there is a tendency to use solder resists for long-term highly reliable electronic materials as printed circuit board solder resists.

[0003] However, conventional alkali-developable solder resist inks generally have poor thermal shock crack resistance and high-temperature storage performance due to reasons such as thermal expansion and contraction. Although selecting barium sulfate as a filler can meet the general use of solder resist inks, it has poor thermal shock crack resistance and unsatisfactory high-temperature storage performance for applications such as in-vehicle use. And it also has an adverse impact on the printability (coverage, sag) and stability (tin resistance, water boiling whitening resistance) of the ink.

[0004] For example, the fillers in the photocurable solder resist ink of Patent Document 1 are silica, barium sulfate, and talc. The curable resin composition for a solder mask of Patent Document 2 contains a carboxyl-containing resin, a thermosetting component, a flame retardant, and an ion-trapping agent, and the ion-trapping agent is a mixture of a hydrotalcite-based ion-trapping agent and an ion-trapping agent other than the hydrotalcite-based one, and aluminum hydroxide is used as the inorganic filler. The curable resin composition of Patent Document 3 is used for a permanent mask of a printed circuit board and includes: a resin containing an ethylenically unsaturated group and a carboxyl group in the molecule, a photoinitiator, a photopolymerizable monomer, titanium oxide surface-treated with alumina, barium sulfate, and / or talc, and an organic solvent. The ultraviolet-curable liquid photosensitive solder resist ink for flexible printed boards of Patent Document 4 describes that the filler is barium sulfate, talc, or silica.

[0005] Patent Document 1: CN114716868A

[0006] Patent Document 2: CN108137791A

[0007] Patent Document 3: CN101798432A

[0008] Patent Document 4: CN106380929A Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] An object of the present invention is to provide an alkaline-developable resin composition, a photocurable dry film thereof and a cured product thereof, and a printed circuit board, which have good printability (covering property, sagging property) and stability (tin resistance, water boiling whitening resistance), and can form a solder resist film having excellent thermal shock resistance and high-temperature storage stability.

[0011] Solutions for Solving the Problems

[0012] The inventors of the present invention conducted repeated and in-depth studies to solve the above problems, and as a result, found that fillers and antioxidants have a great influence on the above-mentioned properties. The alkaline-developable resin composition described below can solve the above problems, and thus the present invention has been completed. The alkaline-developable resin composition is characterized by containing (A) a vinyl ester resin, (B) a photopolymerization initiator, (C) an antioxidant, (D) a compound having two or more ethylenically unsaturated groups in one molecule, and (E) an inorganic filler. Based on 100% by weight of the total amount of the (E) inorganic filler, the content of talc is 50% by weight or more, and based on 100 parts by weight of the (A) vinyl ester resin in terms of solid content, the total content of the (E) inorganic filler is 60 to 180 parts by weight.

[0013] That is, the alkaline-developable resin composition of the present invention is characterized by containing (A) a vinyl ester resin, (B) a photopolymerization initiator, (C) an antioxidant, (D) a compound having two or more ethylenically unsaturated groups in one molecule, and (E) an inorganic filler. Based on 100% by weight of the total amount of the (E) inorganic filler, the content of talc is 50% by weight or more, and based on 100 parts by weight of the (A) vinyl ester resin in terms of solid content, the total content of the (E) inorganic filler is 60 to 180 parts by weight.

[0014] In addition, it is preferably further contains (F) other additives in addition to the (B) photopolymerization initiator and the (C) antioxidant.

[0015] In addition, it is preferably contains (G) an epoxy resin.

[0016] In addition, it is preferably contains (H) an organic solvent.

[0017] In addition, based on 100 parts by weight of the (A) vinyl ester resin in terms of solid content, the amount of the (C) antioxidant used is preferably 3 parts by weight or more.

[0018] In addition, the (E) inorganic filler preferably further contains barium sulfate.

[0019] In addition, the photocurable dry film of the present invention is characterized in that it is obtained by coating the alkali-developable resin composition on a carrier film and drying it.

[0020] In addition, the cured product of the present invention is characterized in that it is obtained by photocuring the following coating film: a coating film obtained by coating the alkali-developable resin composition on copper and drying it; or a coating film obtained by coating the alkali-developable resin composition on a carrier film, drying it, and laminating the obtained photocurable dry film on copper.

[0021] In addition, the printed circuit board of the present invention is characterized in that it is obtained by photocuring the following coating film and then thermally curing it: a coating film obtained by coating the alkali-developable resin composition on a substrate having a copper circuit and drying it; or a coating film obtained by coating the alkali-developable resin composition on a carrier film, drying it, and laminating the obtained photocurable dry film on a substrate having a copper circuit.

[0022] The greatest technical feature of the alkali-developable resin composition of the present invention is that it contains (A) a vinyl ester resin, (B) a photoinitiator, (C) an antioxidant, (D) a compound having two or more ethylenically unsaturated groups in one molecule, and (E) an inorganic filler. Based on the total amount of the (E) inorganic filler being 100% by weight, the content of talc is 50% by weight or more, and based on 100 parts by weight of the (A) vinyl ester resin in terms of solid content, the total content of the (E) inorganic filler is 60 to 180 parts by weight.

[0023] Based on the characteristic constitution of the present invention, by combining and using an antioxidant and talc and adjusting their respective amounts, it is possible to obtain a solder resist film having excellent resistance to thermal shock, high-temperature storage stability, and acid resistance while maintaining good printability (coverage, sagging) and stability (tin plating resistance, water boiling whitening resistance) of the alkali-developable resin composition.

[0024] In contrast, in the prior art, when talc and barium sulfate are used simultaneously as fillers, the acid resistance, tin plating resistance, and water boiling whitening resistance can be improved, but the printability, resistance to thermal shock, and high-temperature storage stability are poor (for example, Patent Document 1, etc.).

[0025] The inventors of the present invention have found through repeated and in-depth research that talc has good flexibility as a filler, excellent anti-cracking performance in the Temperature Cycle Test (hereinafter sometimes simply referred to as the "TCT test"), and excellent high-temperature preservation performance in the Temperature shock Test (hereinafter sometimes simply referred to as the "TS test"). However, its acid resistance deteriorates as the usage amount increases. Barium sulfate, as a traditional filler, can improve acid resistance, but its resistance to thermal shock and high-temperature preservation performance are poor. Even if the usage amounts of both are increased simultaneously, although the high-temperature preservation performance, acid resistance, and stability (tin resistance, water-boiling whitening resistance) can be improved, the resistance to thermal shock and printability (coverage, sag) are still not good. By adding an antioxidant, the acid resistance and stability (tin resistance, water-boiling whitening resistance) can be improved without affecting printability. That is, by combining the use of an antioxidant and talc, an unexpected technical effect is achieved, namely, a solder mask with excellent resistance to thermal shock, high-temperature preservation performance, acid resistance, tin resistance, and water-boiling whitening resistance can be obtained while maintaining good printability (coverage, sag), thus achieving the above object of the present invention.

[0026] Effects of the Invention

[0027] As described above, by using the present invention, an alkaline-developable resin composition, its photocurable dry film and its cured product, and a printed circuit board can be provided, which have good printability (coverage, sag) and stability (tin resistance, water-boiling whitening resistance) of the alkaline-developable resin composition and can form a solder mask with excellent resistance to thermal shock and high-temperature preservation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Photographs showing the cracking of the solder mask used to evaluate the resistance to thermal shock in the examples.

[0029] Figure 2 Photographs showing that the solder mask used to evaluate the resistance to thermal shock in the examples did not crack.

[0030] Figure 3 Photographs showing no peeling in the cross-cut test used to evaluate the high-temperature preservation performance in the examples.

[0031] Figure 4 Photographs showing the covering thickness of the copper corner alkaline-developable resin composition used to evaluate the coverage in the examples.

[0032] Figure 5 Schematic diagrams showing the sag length of the alkaline-developable resin composition measured from the reference horizontal line in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, each component in the alkali-developable resin composition of the present invention will be described.

[0034] The alkali-developable resin composition of the present invention is characterized by containing (C) an antioxidant and (E) an inorganic filler. The (E) inorganic filler contains talc. Based on the total amount of the (E) inorganic filler being 100% by weight, the content of the talc is 50% by weight or more. Based on 100 parts by weight of the (A) vinyl ester resin in terms of solid content, the total content of the inorganic filler is 60 to 180 parts by weight. Therefore, first, the (C) antioxidant and the (E) inorganic filler will be described.

[0035] (C) Antioxidant

[0036] The photosensitive resin composition of the present invention may contain an antioxidant such as a radical scavenger that invalidates the generated free radicals, a peroxide decomposer that decomposes the generated peroxide into harmless substances and prevents the generation of new free radicals, etc. The antioxidant used in the present invention can prevent the oxidative deterioration of resins, etc., and further suppress yellowing. Furthermore, when the inorganic filler contains talc, by adding an antioxidant, in addition to the above effects, the acid resistance of the solder mask and the stability of the ink (tin resistance, water-boiling whitening resistance) can be significantly improved. The antioxidant can be used alone or in combination of two or more.

[0037] As the (C) antioxidant used in the alkali-developable resin composition of the present invention, from the perspective of further facilitating the achievement of the object of the present invention, an antioxidant that functions as a radical scavenger is preferred.

[0038] Examples of antioxidants that act as radical scavengers include: phenolic compounds such as hydroquinone, 4-tert-butylcatechol, 2-tert-butylhydroquinone, methylhydroquinone, pentaerythritol tetra(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), 2,6-di-tert-butyl-p-cresol, 2,2-methylenebis(4-methyl-6-tert-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3’,5’-di-tert-butyl-4-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)-trione; quinone compounds such as p-methoxyphenol and benzoquinone; amine compounds such as bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate and phenothiazine. Examples of commercially available products include: ADEKASTAB AO-30, ADEKASTAB AO-330, ADEKASTAB AO-20, ADEKASTAB LA-77, ADEKASTAB LA-57, ADEKASTAB LA-67, ADEKASTAB LA-68, ADEKASTAB LA-87 (all manufactured by ADEKA CORPORATION, trade names); IRGANOX 1010, IRGANOX 1035, IRGANOX 1076, IRGANOX 1135, TINUVIN 111FDL, TINUVIN 123, TINUVIN 144, TINUVIN 152, TINUVIN 292, TINUVIN 5100 (all manufactured by BASF JAPAN LTD., trade names); CHINOX TP-10H (manufactured by Double Bond Chemical Industry Co., Ltd., trade name), etc.

[0039] Examples of antioxidants that act as peroxide decomposers include: phosphorus compounds such as triphenyl phosphite; sulfur compounds such as pentaerythritol tetra(lauryl thiodipropionate), dilauryl thiodipropionate, and distearyl 3,3’-thiodipropionate. Examples of commercially available products include: ADEKASTAB TPP (manufactured by ADEKA CORPORATION, trade name), MARK AO-412S (manufactured by ADEKA CORPORATION, trade name), Sumilizer TPS (manufactured by Sumitomo Chemical Co., Ltd., trade name), etc.

[0040] Regarding the compounding ratio of the (C) antioxidant, it is suitable to be 0.1 to 20 parts by weight, preferably 1 to 15 parts by weight, more preferably 3 to 12 parts by weight, and further preferably 3 to 10 parts by weight relative to 100 parts by weight of the (A) vinyl ester resin based on solid content. When the amount of the (C) antioxidant used is within the above range, it can ensure that, without affecting printability, the acid resistance of the solder mask and the stability of the ink (resistance to tin plating, resistance to whitening upon boiling water) are significantly improved.

[0041] (E) Inorganic Filler

[0042] As described above, in the alkaline-developable resin composition of the present invention, the talc used as the (E) inorganic filler is used to improve the resistance to thermal shock and high-temperature storage.

[0043] As the talc, the mother rock can be any one of magnesium carbonate, serpentine, silica / silica-alumina, and magnesium deposits, and it can be a so-called silicate mineral. The shape can be massive or micro-powdery. Surface treatment can be carried out or not. It is suitable that the average particle size of the talc is 1.0 - 20.0 μm, more preferably 2.0 - 10 μm, and further preferably 3.0 - 8.0 μm. Commercially available products include HD25 manufactured by Pingdu Talc Mining Co., Ltd. in Shandong Province, LMP-100 manufactured by Fuji Talc Industry Co., Ltd., etc. If the (E) inorganic filler consists only of talc, the printability is particularly excellent.

[0044] Talc can improve the printability of the alkaline-developable resin composition and the resistance to thermal shock and high-temperature storage of the solder mask, but the acid resistance deteriorates as the usage amount increases. Therefore, from the perspective of achieving each effect of the present invention in a balanced manner, based on the total amount of the (E) inorganic filler being 100% by weight, the content of talc is suitably 50% by weight or more, more preferably 55% by weight or more, and further preferably 60% by weight or more.

[0045] Within the range not affecting the object of the present invention, other fillers other than talc, such as barium sulfate, can also be compounded. The use of barium sulfate can improve acid resistance, but as its usage amount increases, it will have an adverse effect on the printability (coverage, sag) and stability (resistance to tin plating, resistance to whitening upon boiling water) of the alkaline-developable resin composition, as well as the resistance to thermal shock and high-temperature storage of the solder mask.

[0046] Commercially available products of barium sulfate can include B-30, B-31, B-32, B-33, B-34, B-35, B-35T, etc. manufactured by Sakai Chemical Industry Co., Ltd.

[0047] The shapes of the inorganic filler can include spherical, needle-like, flaky, scaly, hollow, irregular, hexagonal, cubic, lamellar, etc.

[0048] Regarding the total content of the inorganic filler, from the viewpoints of taking into account the printability of the alkali-developable resin composition, the thermal shock resistance of the solder resist film, and the high-temperature storage stability, with respect to 100 parts by weight of the (A) vinyl ester resin in terms of solid content, it is preferably 60 to 180 parts by weight, more preferably 80 to 160 parts by weight, and still more preferably 90 to 150 parts by weight.

[0049] (A) Vinyl Ester Resin

[0050] As the (A) vinyl ester resin in the photocurable and thermosetting resin composition of the present invention, from the viewpoints of photocurability and developability, a known resin containing an ethylenically unsaturated double bond in the molecule can be used. In addition, in order to impart alkali developability, a carboxyl group-containing resin having an ethylenically unsaturated double bond in the molecule is particularly preferred. Furthermore, it is more preferably that the unsaturated double bond is derived from acrylic acid or methacrylic acid or their derivatives. As the (A) vinyl ester resin, a resin starting from an epoxy resin, a polyurethane resin having a urethane skeleton, a copolymer resin having a copolymer structure of an unsaturated carboxylic acid, and a resin starting from a phenolic compound are preferred. Specific examples of the (A) vinyl ester resin are shown below.

[0051] (1) A vinyl ester resin obtained by copolymerizing an unsaturated carboxylic acid such as (meth)acrylic acid with one or more other compounds having an unsaturated double bond;

[0052] (2) A photosensitive vinyl ester resin obtained by adding an ethylenically unsaturated group in the form of a side group to a copolymer of an unsaturated carboxylic acid such as (meth)acrylic acid and one or more other compounds having an unsaturated double bond, using a compound having an epoxy group and an unsaturated double bond such as glycidyl (meth)acrylate or 3,4-epoxycyclohexylmethyl (meth)acrylate, and (meth)acryloyl chloride, etc.;

[0053] (3) A photosensitive vinyl ester resin obtained by reacting a copolymer of a compound having an epoxy group and an unsaturated double bond such as glycidyl (meth)acrylate or 3,4-epoxycyclohexylmethyl (meth)acrylate and one or more other compounds having an unsaturated double bond, with an unsaturated carboxylic acid such as (meth)acrylic acid, and reacting a polyacid anhydride with the resulting secondary hydroxyl group;

[0054] (4) A photosensitive vinyl ester resin obtained by reacting a copolymer of an acid anhydride having an unsaturated double bond such as maleic anhydride and one or more other compounds having an unsaturated double bond, with a compound having a hydroxyl group and an unsaturated double bond such as 2-hydroxyethyl (meth)acrylate;

[0055] (5) A vinyl ester resin obtained by reacting a polyfunctional epoxy compound with an unsaturated monocarboxylic acid and reacting a saturated or unsaturated polycarboxylic anhydride with the resulting hydroxyl groups;

[0056] (6) A vinyl ester resin containing hydroxyl and carboxyl groups obtained by reacting a hydroxyl group-containing polymer such as a polyvinyl alcohol derivative with a saturated or unsaturated polycarboxylic anhydride and then reacting a compound having an epoxy group and an unsaturated double bond in one molecule with the resulting carboxylic acid;

[0057] (7) A vinyl ester resin obtained by reacting a reaction product of a polyfunctional epoxy compound and an unsaturated monocarboxylic acid with a compound having at least one alcoholic hydroxyl group and one reactive group other than the alcoholic hydroxyl group that reacts with an epoxy group in one molecule, with a saturated or unsaturated polycarboxylic anhydride;

[0058] (8) A vinyl ester resin obtained by reacting an unsaturated monocarboxylic acid with a polyfunctional oxetane compound having at least two oxetane rings in one molecule and reacting a saturated or unsaturated polycarboxylic anhydride with the primary hydroxyl groups in the resulting modified oxetane resin; and

[0059] (9) A vinyl ester resin obtained by further reacting a carboxyl group-containing resin obtained by reacting an unsaturated monocarboxylic acid with a polyfunctional epoxy resin and then with a polycarboxylic anhydride, with a compound having one oxirane ring and more than one ethylenically unsaturated group in the molecule;

[0060] (10) A vinyl ester resin obtained by reacting a bifunctional epoxy compound with an unsaturated monocarboxylic acid and reacting a saturated or unsaturated polycarboxylic anhydride with the resulting hydroxyl groups.

[0061] As particularly preferred substances among these examples, are the vinyl ester resins of the above (2), (5), (7), and (9).

[0062] It should be noted that in this specification, (meth)acrylate is a term collectively referring to acrylate, methacrylate, and their mixtures, and the same applies to other similar expressions.

[0063] The above-mentioned (A) vinyl ester resin can be developed using a dilute aqueous alkali solution because it has multiple free carboxyl groups on the side chains of the main-chain polymer.

[0064] It should be noted that in this specification, polymer is a term collectively referring to homopolymers, copolymers, and their mixtures, and the same applies to other similar expressions.

[0065] In addition, the acid value of the above-mentioned (A) vinyl ester resin is preferably in the range of 40 to 200 mgKOH / g, more preferably in the range of 45 to 120 mgKOH / g. When the acid value of the carboxyl group-containing resin is less than 40 mgKOH / g, alkali development is difficult. On the other hand, when it exceeds 200 mgKOH / g, the developer will promote the dissolution of the exposed part, so the line becomes thinner than required, and sometimes the exposed part and the unexposed part are dissolved and peeled off by the developer without distinction, making it difficult to draw a normal resist pattern, so it is not preferred.

[0066] In addition, the weight average molecular weight of the above-mentioned (A) vinyl ester resin varies depending on the resin skeleton, and is usually preferably in the range of 2000 to 150000, more preferably in the range of 5000 to 100000. When the weight average molecular weight is less than 2000, sometimes the non-sticky performance after coating and drying on the substrate deteriorates. In addition, sometimes the moisture resistance of the coated film after exposure deteriorates, film reduction occurs during development, and the resolution deteriorates significantly. On the other hand, when the weight average molecular weight exceeds 150000, sometimes the developability deteriorates significantly and the storage stability deteriorates.

[0067] The blending amount of the (A) vinyl ester resin is desirably in the range of 20 to 60% by mass of the total composition based on the solid content, preferably 25 to 50% by mass. When the blending amount of the (A) vinyl ester resin is less than the above range, the film strength decreases, so it is not preferred. On the other hand, when it is more than the above range, the viscosity of the composition becomes high or the coatability decreases, so it is not preferred.

[0068] (B) Photoinitiator

[0069] There is no particular limitation on the photoinitiator used in the basic developing type resin composition of the present invention as long as it is a photoinitiator commonly used in basic developing type resin compositions.

[0070] As the photoinitiator, known substances can be used, and examples include: benzoin and its alkyl ethers such as benzoin, benzoin methyl ether, and benzoin ethyl ether; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, and 4-(1-tert-butyldioxy-1-methylethyl)acetophenone; anthraquinones such as 2-methylanthraquinone, 2-pentylanthraquinone, 2-tert-butylanthraquinone, and 1-chloroanthraquinone; thioxanthones such as isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, and 2-chlorothioxanthone; ketals such as acetophenone dimethyl ketal and benzil dimethyl ketal; benzophenones such as benzophenone, 4-(1-tert-butyldioxy-1-methylethyl)benzophenone, and 3,3’,4,4’-tetra(tert-butyldioxycarbonyl)benzophenone; and xanthenones.

[0071] In addition, as a photopolymerization initiator, an oxime ester-based photopolymerization initiator having an oxime ester group, an alkyl phenyl ketone-based photopolymerization initiator, an α-aminoacetophenone-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, a titanocene-based photopolymerization initiator, a phosphate ester-based photopolymerization initiator, etc. can also be used.

[0072] As commercially available products of the oxime ester-based photopolymerization initiator, Irgacure OXE01, Irgacure OXE02 manufactured by BASF Japan Co., Ltd., N-1919, NCI-831 manufactured by ADEKA CORPORATION, etc. can be cited. A photopolymerization initiator having 2 oxime ester groups in the molecule can be preferably used, and specifically, an oxime ester compound having a carbazole ring structure can be cited.

[0073] As commercially available products of the alkyl phenyl ketone-based photopolymerization initiator, α-hydroxyalkyl phenyl ketone-based such as Omnirad 184, Omnirad 1173, Omnirad 2959, Omnirad 127 manufactured by IGM Resins B.V. can be cited.

[0074] As the α-aminoacetophenone-based photopolymerization initiator, specifically, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholin-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, N,N-dimethylaminoacetophenone, etc. can be cited. As commercially available products, Omnirad 907, Omnirad 369, Omnirad 379 manufactured by IGM Resins B.V. can be used.

[0075] As the acylphosphine oxide-based photopolymerization initiator, specifically, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, a polyfunctional acylphosphine-based photopolymerization initiator having 3 or more functional groups, etc. can be cited. The polyfunctional acylphosphine-based photopolymerization initiator having 3 or more functional groups can be a photopolymerization initiator having 3 or more acylphosphine oxide skeletons in 1 molecule, and can be represented by the following formula (I).

[0076]

[0077] In the formula,

[0078] A independently represents a single bond, O, S or NR 3 ;

[0079] G is a polyfunctional compound (core) G-(A-H) m+n residue, where each of A-H represents an alcohol group, an amino group, or a thiol group;

[0080] Both m and n are integers, and m + n is an integer between 3 and 10;

[0081] m is an integer between 3 and 8;

[0082] R1 and R2 are independently of each other a C1-C 18 alkyl group, a C6-C 12 aryl group, and a C5-C 12 cycloalkyl group, each of which is not broken or is broken by the following groups: one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups, or R1 and R2 are independently of each other a five- to six-membered heterocyclic group containing oxygen and / or nitrogen and / or sulfur atoms, where the aforementioned groups are each optionally substituted by an aryl group, an alkyl group, an aryloxy group, an alkoxy group, a heteroatom, and / or a heterocyclic group;

[0083] R2 can be R1-(C=O)-;

[0084] Y is O or S;

[0085] R3 is hydrogen or a C1-C4 alkyl group;

[0086] Among them, the photoinitiator of formula (I) does not contain a photocurable ethylenically unsaturated group.

[0087] Preferably, in formula (I), m + n is an integer between 3 and 8, more preferably an integer between 3 and 6. For example, in formula I, m is an integer between 3 and 6, more preferably an integer between 3 and 5.

[0088] In formula (I), when A is oxygen, G-(A-H) m+n is a polyhydroxy (polyhydric alcohol) compound, selected from the group consisting of monomeric polyols, oligomeric polyols, polymeric polyols, and mixtures thereof. When A is sulfur, G-(A-H) m+n is a polythiol compound. In formula (I), when A is nitrogen, G-(A-H) m+n is a linear or branched polyamine. When A is a mixture of oxygen and / or nitrogen and / or sulfur, G-(A-H) m+n is a compound containing different functional groups, such as a compound containing an amino group and a hydroxyl group. The residue G- suitable for the implementation of the present invention does not contain a photocurable ethylenically unsaturated group. When A is a single bond, G- is the residue after removing a hydroxyl group and / or an amino group and / or a mercapto group from the above-listed G-(A-H) m+n

[0089] Preferably G-(A-H) m+n ​Having a number average molecular weight of 1500 or less, more preferably 800 or less, and still more preferably 500 or less.

[0090] When n is not 0, the compound of formula (I) has an alcoholic free radical and / or an amino group and / or a mercapto group.

[0091] Representative acylphosphine-based photoinitiators having three or more functional groups included in formula (I) are shown in Table 1. Among these, PI-3, PI-4, PI-10, PI-11, PI-12, PI-14, and PI-17 are particularly preferred. By including such an acylphosphine-based photoinitiator having three or more functional groups, a cured product with suppressed outgassing and more excellent insulation reliability can be obtained.

[0092] Table 1

[0093]

[0094]

[0095]

[0096]

[0097]

[0098] Such an acylphosphine-based photoinitiator having three or more functional groups can be produced, for example, by the method described in Japanese Patent No. 6599446.

[0099] As commercially available products of acylphosphine oxide-based photoinitiators, Omnirad TPO manufactured by IGM Resins, Omnirad 819 manufactured by IGM Resins B.V., Omnipol TP, etc. can be used.

[0100] As the aforementioned titanocene-based photoinitiator, specifically, bis(cyclopentadienyl)-diphenyltitanium, bis(cyclopentadienyl)-dichlorotitanium, bis(cyclopentadienyl)-bis(2,3,4,5,6-pentafluorophenyl)titanium, bis(cyclopentadienyl)-bis(2,6-difluoro-3-(pyrrol-1-yl)phenyl)titanium, etc. can be cited. As commercially available products, Omnirad 784 manufactured by IGM Resins B.V. can be cited.

[0101] Regarding the compounding ratio of these photoinitiators (B), it is suitable that the amount is 0.01 to 30 parts by weight, preferably 5 to 25 parts by weight, more preferably 10 to 20 parts by weight, relative to 100 parts by weight of the (A) vinyl ester resin in terms of solid content. When the amount of the photoinitiator used is less than the above range, the photocurability of the composition deteriorates. On the other hand, when it is excessive, the properties as a solder resist decrease, so it is not preferred.

[0102] (D) Compound Having Two or More Ethylenically Unsaturated Groups in One Molecule The compound (D) having two or more ethylenically unsaturated groups in one molecule used in the alkali-developable resin composition of the present invention is a compound that cures by irradiation with actinic energy rays to make the aforementioned (A) vinyl ester resin insoluble in an aqueous alkali solution or contributes to the insolubility of the aforementioned vinyl ester resin in an aqueous alkali solution. Specific examples of such compounds include:

[0103] Hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate;

[0104] Monoacrylates or diacrylates of diols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, and propylene glycol;

[0105] Acrylamides such as N,N-dimethylacrylamide, N-hydroxymethylacrylamide, and N,N-dimethylaminopropylacrylamide;

[0106] Aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate and N,N-dimethylaminopropyl acrylate;

[0107] Polyacrylates of polyols such as hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, and trihydroxyethyl isocyanurate, or their ethylene oxide adducts or propylene oxide adducts;

[0108] Acrylates such as phenoxy acrylate, bisphenol A diacrylate, and ethylene oxide adducts or propylene oxide adducts of these phenols;

[0109] Acrylates of glycidyl ethers such as glycerol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate;

[0110] And at least any one of melamine acrylate and each methacrylate corresponding to the above acrylates.

[0111] Furthermore, it is also possible to list: epoxy acrylate resins formed by reacting polyfunctional epoxy resins such as cresol novolac type epoxy resins with acrylic acid, and epoxy urethane acrylate compounds formed by further reacting the hydroxyl groups of the epoxy acrylate resins with hydroxyl acrylate esters such as pentaerythritol triacrylate and half urethane compounds of diisocyanates such as isophorone diisocyanate, etc.

[0112] With respect to 100 parts by weight of the aforementioned (A) vinyl ester resin in terms of solid content, the compounding amount of such a compound (D) having two or more ethylenically unsaturated groups in one molecule is desirably in the ratio of 5 to 100 parts by weight, more preferably in the ratio of 10 to 70 parts by weight. When the compounding amount is less than 5 parts by weight with respect to 100 parts by weight of the (A) vinyl ester resin, the photocurability of the alkali-developable resin composition obtained is reduced, and it is difficult to form a pattern by alkali development after irradiation with active energy rays, so it is not preferred. On the other hand, when it exceeds 100 parts by weight, the solubility in an aqueous alkali solution is reduced and the cured coating film becomes brittle, so it is not preferred.

[0113] (F) Other Additives

[0114] As described above, other additives in the present invention refer to additives other than (B) photoinitiator and (C) antioxidant.

[0115] As such additives, there can be listed: publicly known and commonly used colorants such as phthalocyanine blue, phthalocyanine green, iodine green, bisazo yellow, crystal violet, titanium oxide, carbon black, naphthol black, etc., publicly known and commonly used thermal polymerization inhibitors, thickeners such as fine silica, organobentonite, montmorillonite, etc., and at least any one of defoamers and leveling agents such as silicone-based, fluorine-based, and polymer-based, adhesion-imparting agents such as imidazole-based, thiazole-based, and triazole-based, silane coupling agents, hindered amine light stabilizers, and other such publicly known and commonly used additive classes.

[0116] The compounding ratio of such (F) other additives is suitably 0.01% by weight or more and 20% by weight or less of the total amount of the alkali-developable resin composition. When it is less than 0.01% by weight, the corresponding effects cannot be fully obtained, and when it exceeds 20% by weight, the printability and hardness of the alkali-developable resin composition deteriorate, so it is not preferred.

[0117] (G) Epoxy Resin

[0118] In order to impart heat resistance, it is preferred to compound an epoxy resin having at least 2 epoxy groups in the molecule, that is, a polyfunctional epoxy resin (G), in the alkali-developable resin composition used in the present invention.

[0119] As commercially available products, for example, there can be cited: jER828, jER834, jER1001, jER1004 manufactured by Mitsubishi Chemical Corporation; EPICLON 840, 850, 850S, 1050, 2055 manufactured by DIC Corporation; EPOTOTE YD-011, YD-013, YD-127, YD-128 manufactured by NIPPON STEEL Chemical & Material Co., Ltd.; D.E.R.317, D.E.R.331, D.E.R.661, D.E.R.664 manufactured by Dow Chemical Company; Sumi-Epoxy ESA-011, ESA-014, ELA-115, ELA-128 manufactured by Sumitomo Chemical Co., Ltd. (all are trade names) bisphenol A type epoxy resins; jERYL903 manufactured by Mitsubishi Chemical Corporation; EPICLON 152, EPICLON 165 manufactured by DIC Corporation; EPOTOTE YDB-400, YDB-500 manufactured by NIPPON STEEL Chemical & Material Co., Ltd.; D.E.R.542 manufactured by Dow Chemical Company; Sumi-Epoxy ESB-400, ESB-700 manufactured by Sumitomo Chemical Co., Ltd. (all are trade names) brominated epoxy resins; jER152, jER154 manufactured by Mitsubishi Chemical Corporation; D.E.N.431, D.E.N.438 manufactured by Dow Chemical Company; EPICLON N-730, EPICLON N-770, EPICLON N-865 manufactured by DIC Corporation; EPOTOTE YDCN-701, YDCN-704 manufactured by NIPPON STEEL Chemical & Material Co., Ltd.; EPPN-201, EOCN-1025, EOCN-1020, EOCN-104S, RE-306, NC-3000 manufactured by Nippon Kayaku Co., Ltd.; Sumi-Epoxy ESCN-195X, ESCN-220 manufactured by Sumitomo Chemical Co., Ltd.; NIPPON STEEL Chemical & Material Co., Ltd.Phenolic varnish type epoxy resins such as YDCN-700-2, YDCN-700-3, YDCN-700-5, YDCN-700-7, YDCN-700-10, YDCN-704, YDCN-704A (trade names), EPICLON N-680, N-690, N-695, etc. (trade names) manufactured by DIC Corporation; Bisphenol F type epoxy resins such as EPICLON 830 manufactured by DIC Corporation, jER807 manufactured by Mitsubishi Chemical Corporation, EPOTOTE YDF-170, YDF-175, YDF-2004, etc. (trade names) manufactured by NIPPON STEEL Chemical & Material Co., Ltd.; Hydrogenated bisphenol A type epoxy resins such as EPOTOTE ST-2004, ST-2007, ST-3000 (trade name) manufactured by NIPPON STEEL Chemical & Material Co., Ltd., YX8034 manufactured by Mitsubishi Chemical Corporation; Glycidylamine type epoxy resins such as jER604 manufactured by Mitsubishi Chemical Corporation, EPOTOTE YH-434 manufactured by NIPPON STEEL Chemical & Material Co., Ltd., Sumi-Epoxy ELM-120 etc. (trade names) manufactured by Sumitomo Chemical Industry Co., Ltd.; Hydantoin type epoxy resins; Alicyclic epoxy resins such as CELLOXIDE 2021P etc. (trade name) manufactured by Daicel Corporation; Trihydroxyphenylmethane type epoxy resins such as YL-933 manufactured by Mitsubishi Chemical Corporation, EPPN-501, EPPN-502, etc. (trade names) manufactured by Nippon Kayaku Co., Ltd.; Bixylenol type or biphenol type epoxy resins or their mixtures such as YL-6056, YX-4000, YL-6121 (trade names) etc. manufactured by Mitsubishi Chemical Corporation; Bisphenol S type epoxy resins such as EBPS-200 manufactured by Nippon Kayaku Co., Ltd., EPX-30 manufactured by ADEKA CORPORATION, EXA-1514 (trade name) manufactured by DIC Corporation; Bisphenol A phenolic varnish type epoxy resins such as jER157S (trade name) manufactured by Mitsubishi Chemical Corporation; Tetrahydroxyphenylethane type epoxy resins such as jERYL-931 etc. (trade name) manufactured by Mitsubishi Chemical Corporation; Heterocyclic epoxy resins such as TEPIC etc. (trade name) manufactured by Nissan Chemical Industries, Ltd.; Phthalic acid diglycidyl ester resins such as BRENMAR DGT manufactured by NOF Corporation; Tetraglycidyl xylylenediamide resins such as ZX-1063 etc. manufactured by NIPPON STEEL Chemical & Material Co., Ltd.; NIPPON STEEL Chemical & Material Co., Ltd.Manufacture ESN-190, ESN-360, HP-4032, EXA-4750, EXA-4700, etc. containing naphthalene skeleton oxygen resins manufactured by DIC Corporation; glycidyl methacrylate copolymer epoxy resins such as CP-50S and CP-50M manufactured by NOF Corporation; furthermore, copolymer epoxy resins of cyclohexyl maleimide and glycidyl methacrylate; CTBN-modified epoxy resins (for example, YR-102, YR-450, etc. manufactured by NIPPON STEEL Chemical&Material Co.,Ltd.), etc., but not limited to these. These epoxy resins can be used alone or in combination of two or more kinds.

[0120] (G) The content of the epoxy resin is preferably 10 to 100 parts by weight, more preferably 20 to 90 parts by weight, and further preferably 30 to 80 parts by weight with respect to 100 parts by weight of the (A) vinyl ester resin in terms of solid content.

[0121] (H) Organic Solvent

[0122] Regarding the organic solvent (H) that can be used in the alkaline-developable resin composition of the present invention, an organic solvent can be used for synthesizing the (A) vinyl ester resin, preparing the composition, or adjusting the viscosity for coating on a substrate or a carrier film.

[0123] Examples of such organic solvents include: ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum solvents, etc. More specifically, ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and durene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, naphtha, hydrogenated naphtha, and solvent naphtha. The above organic solvents can be used alone or in the form of a mixture of two or more kinds.

[0124] When the basic developing type resin composition of the present invention is used in forming a solder resist film of a printed circuit board, after adjusting the viscosity to suit the coating method as required, it is coated on a printed circuit board having a circuit formed thereon in advance by methods such as screen printing method, curtain coating method, spraying method, roll coating method, etc. As required, for example, by drying at a temperature of about 60 to 100 °C, a non-sticky coating film can be formed. Then, through a photomask having a specified exposure pattern formed thereon, the unexposed portion is selectively exposed to active light, and the unexposed portion is developed with an alkaline aqueous solution to form a resist pattern. Further, for example, by heating to a temperature of about 140 to 180 °C to thermally cure it, the curing reaction of (G) epoxy resin and the polymerization of (A) vinyl ester resin can be promoted, and various properties such as heat resistance, solvent resistance, acid resistance, moisture absorption resistance, PCT tolerance, adhesion, and electrical properties of the obtained resist coating film can be improved. It should be noted that the photocuring reaction can also be further promoted by adding a UV irradiation step before or after the thermal curing by heating.

[0125] As the alkaline aqueous solution used in the above development, an alkaline aqueous solution such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, amines, etc. can be used. In addition, as the irradiation light source for photocuring, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a semiconductor laser, a solid laser, a xenon lamp, or a metal halide lamp, etc. is suitable.

[0126] In addition to the method of directly coating the basic developing type resin composition of the present invention in a liquid state on a substrate having a copper circuit, it can also be used in the form of a photocurable dry film obtained by previously coating the basic developing type resin composition on a carrier film and drying it. The following shows the case of using the basic developing type resin composition of the present invention in the form of a photocurable dry film.

[0127] The photocurable dry film has a structure in which a carrier film, a resin layer, and an optional peelable cover film are laminated in sequence. The resin layer is a layer obtained by coating the basic developing type resin composition of the present invention on the carrier film and drying it. After the resin layer is formed on the carrier film, the cover film is laminated thereon to obtain a photocurable dry film.

[0128] As the carrier film, a thermoplastic film such as a polyester film with a thickness of 2 to 150 μm can be used. The resin layer is formed by uniformly coating the basic developing type resin composition on the carrier film with a thickness of 10 to 150 μm using a doctor blade coater, a lip coater, a comma coater, a film coater, etc. and drying it. As the cover film, a polyethylene film, a polypropylene film, etc. can be used, and a cover film with an adhesive force to the resin layer smaller than the adhesive force between the carrier film and the resin layer is preferably used.

[0129] The cured product of the present application is obtained by photocuring the following coating film, and the coating film is: a coating film obtained by coating an alkali-developable resin composition on copper and drying; or a coating film obtained by coating the alkali-developable resin composition on a carrier film and drying, and laminating the obtained photocurable dry film on copper.

[0130] For fabricating a cured product on a substrate having a copper circuit using a photocurable dry film, the cover film is peeled off, the resin layer is overlapped with the substrate having the copper circuit, and they are bonded using a laminator or the like to form a resin layer on the substrate having the copper circuit. When the formed resin layer is exposed, developed, and heat-cured in the same manner as described above, a cured product can be formed. The carrier film can be peeled off before or after exposure.

[0131] The alkali-developable resin composition is suitable for forming a cured coating film on a printed circuit board. As the cured coating film, a permanent insulating coating film is preferred, and a solder resist layer is particularly preferred.

[0132] Examples

[0133] The present invention will be described in more detail based on examples and comparative examples, but the protection scope and implementation mode of the present invention are not limited to these. In the examples and comparative examples, "parts" or "%" are based on weight unless otherwise specified. The property value tests of the compositions of the present examples were carried out by the methods described below.

[0134] Synthesis Examples

[0135] 214 parts of a cresol novolak type epoxy resin EPICLON N-695 (manufactured by DIC, epoxy equivalent = 214) were put into a four-necked flask equipped with a stirrer and a reflux condenser, 103 parts of carbitol acetate and 103 parts of a petroleum-based hydrocarbon solvent (trade name: Cactus Fines SF-01, manufactured by Japan Energy Corporation) were added and heated for dissolution. Then, 0.1 part of hydroquinone as a polymerization inhibitor and 2.0 parts of triphenylphosphine as a reaction catalyst were added. The mixture was heated to 95 - 105 °C, and 72 parts of acrylic acid was slowly added dropwise and reacted for 16 hours. The obtained reaction product was cooled to 80 - 90 °C, 91.2 parts of tetrahydrophthalic anhydride was added and reacted for 8 hours, and then taken out after cooling. The non-volatile content of the carboxyl group-containing vinyl ester resin obtained by such operation was 65%, and the acid value of the solid content was 87.5 mgKOH / g.

[0136] Using the vinyl ester resin solution (varnish) of the synthesis example, compounding was carried out with various components and ratios (parts by weight) shown in Table 1. After premixing with a stirrer, it was kneaded with a three-roll mill to prepare an alkali-developable resin composition. And the resistance to thermal shock (TCT test), high-temperature storage property (TS test), printability (covering property, sagging), acid resistance, and stability (resistance to tin plating, resistance to whitening by boiling water) were evaluated according to the following methods.

[0137] Table 1

[0138]

[0139] "-" indicates not added

[0140] The carboxyl group-containing vinyl ester resin of Synthesis Example A, with a solid content of 65%, corresponding to the carboxyl group-containing vinyl ester resin of (5)

[0141] F Pigment: Phthalocyanine Green, manufactured by Dainippon Ink and Chemicals, Inc. Pigment AF Antifoaming agent: KS-66, manufactured by Shin-Etsu Chemical Co., Ltd.

[0142] C Antioxidant: IRGANOX 1010, manufactured by BASF JAPAN LTD. B Photoinitiator: Omnirad 369E, manufactured by IGM

[0143] E Talc: LMP-100, manufactured by FUJI TALC INDUSTRIAL Co., Ltd. E Barium sulfate: B-30, manufactured by Sakai Chemical Industry Co., Ltd. H Solvent: PGMEA, propylene glycol monomethyl ether acetate

[0144] G Epoxy resin: N-770-75EA, manufactured by DIC Corporation, a novolak-type polyfunctional epoxy resin, with a solid content of 75%

[0145] D Compound having two or more ethylenically unsaturated groups in one molecule: MT-3501G, manufactured by Zhangjiagang East Asia Dioxybenzone Chemical Co., Ltd.

[0146] Performance Evaluation:

[0147] (1) Resistance to thermal shock (TCT test)

[0148] The alkali-developable resin compositions of the examples and comparative examples were screen-printed and coated over the entire surface on a substrate having a 2-mm copper wire pattern so that the thickness became 40 μm, and dried in a hot air circulation drying oven at 80 °C for 30 minutes. After cooling to room temperature, an exposure apparatus equipped with a high-pressure mercury lamp was used at 400 mJ / cm 2Perform pattern exposure, then develop for 60 seconds in an aqueous sodium carbonate solution of 1 wt%, at a pressure of 0.2 MPa and a liquid temperature of 30 °C, and then cure at 150 °C for 60 minutes in a hot air circulation drying oven. By irradiating ultraviolet rays in a UV conveyor oven under the condition of an accumulated exposure dose of 2000 mJ / cm 2 a thermal shock crack resistance evaluation substrate with 17 resist patterns having a right-angled shape was fabricated. A plurality of the evaluation substrates fabricated as above were placed in a thermal shock machine that cycles the temperature between -40 °C and 160 °C and different cycle numbers were set, and a thermal shock cycle test (TCT test) was conducted. Then, the appearance at each cycle number was observed, and the cycle number at which no cracks occurred was recorded (for the presence or absence of cracks, refer to Figure 1 and Figure 2 ), and the evaluation criteria are as follows.

[0149] ○: No cracks after 1000 cycles

[0150] ×: Cracks occurred before 1000 cycles

[0151] (2) High-temperature storage stability (TS test)

[0152] The above evaluation substrates were placed in an oven at 160 °C and different placement times were set, and a cross-cut test was conducted as follows. Record the maximum number of hours when there is no peeling in the cross-cut test.

[0153] Cross-cut test: After irradiating ultraviolet rays in the above UV conveyor oven, use a brand-new blade to draw grids on the surface of the solder mask with a force of 30° to the board surface, and conduct a peeling test with 3M tape (see Figure 3 ).

[0154] ○: The high-temperature storage time without peeling in the cross-cut test reaches 1000 hours or more

[0155] ×: The high-temperature storage time without peeling in the cross-cut test is less than 1000 hours

[0156] (3) Coverage

[0157] After the alkaline-developable resin composition shown in Table 1 was screen-printed onto the copper circuit of a printed circuit board, the coverage of the alkaline-developable resin composition on the individual circuits was observed, and the coverage thickness of the alkaline-developable resin composition at the copper corners was compared and evaluated. The thickness of the copper circuit is about 70 μm (see Figure 4 ).

[0158] ○: The coverage thickness of the alkaline-developable resin composition is 10 μm or more

[0159] ×: The coverage thickness of the alkaline-developable resin composition is less than 10 μm

[0160] (4) Sag

[0161] Draw a starting horizontal line on the large copper surface substrate with an oil-based pen. Draw up 0.2 ml of the alkaline-developable resin composition with a 1-ml disposable syringe, and coat the alkaline-developable resin composition on the copper surface substrate. Stand the large copper surface substrate coated with the alkaline-developable resin composition on the substrate rack, and bake it in a hot air circulation drying oven at 80 °C for 30 min. After drying, measure the sag length starting from the reference horizontal line (see Figure 5 ).

[0162] ○: Sag length is 5 cm or less

[0163] ×: Sag length is greater than 5 cm

[0164] (5) Acid resistance

[0165] Coat the alkaline-developable resin compositions of the examples and comparative examples on the substrate with a 2-mm copper wire pattern formed thereon by screen printing so that the thickness becomes 40 μm, and dry it in a hot air circulation drying furnace at 80 °C for 30 minutes. After cooling to room temperature, perform pattern exposure using an exposure device equipped with a high-pressure mercury lamp at 400 mJ / cm 2 , then develop for 60 seconds at 30 °C under a pressure of 0.2 MPa in a 1 wt% sodium carbonate aqueous solution, and cure at 150 °C for 60 minutes in a hot air circulation drying furnace to produce an evaluation substrate with a solder mask. Immerse this evaluation substrate in a 10 vol% H2SO4 aqueous solution at room temperature for 20 minutes, visually confirm the infiltration between the solder mask and the substrate and the dissolution of the flame retardant film, and further confirm the peeling caused by tape peeling.

[0166] ○: No change was observed

[0167] △: Only slightly changed

[0168] ×: There are bulges or swelling and peeling of the coating film

[0169] (6) Tin resistance (welding heat resistance)

[0170] Coat the alkaline-developable resin compositions of the examples and comparative examples on the substrate with a 2-mm copper wire pattern formed thereon by screen printing so that the thickness becomes 40 μm, and dry it in a hot air circulation drying furnace at 80 °C for 30 minutes. After cooling to room temperature, perform pattern exposure using an exposure device equipped with a high-pressure mercury lamp at 400 mJ / cm 2Pattern exposure was carried out, followed by development for 60 seconds in an aqueous solution of sodium carbonate at 1 wt%, a pressure of 0.2 MPa, and a liquid temperature of 30°C. Then, curing was performed at 150°C for 60 minutes in a hot air circulation drying oven to produce an evaluation substrate with a solder resist film. A rosin-based soldering flux was coated on the solder resist film of the evaluation substrate. The evaluation substrate coated with the rosin-based soldering flux was immersed in a solder bath pre-set at 260°C. After washing the flux with a modified alcohol, the swelling and peeling of the solder resist film were evaluated visually. The judgment criteria are as follows.

[0171] ○: No peeling was observed even when immersion for 10 seconds was repeated more than 3 times.

[0172] △: Slight peeling occurred when immersion for 10 seconds was repeated more than 3 times.

[0173] ×: Swelling and peeling of the solder resist film occurred when immersion for 10 seconds was repeated within 3 times.

[0174] (7) Resistance to whitening in boiling water

[0175] The alkaline-developable resin compositions of the examples and comparative examples were coated over the entire surface of a substrate with a 2-mm copper wire pattern by screen printing to a thickness of 40 μm, and dried in a hot air circulation drying oven at 80°C for 30 minutes. After cooling to room temperature, pattern exposure was carried out using an exposure device equipped with a high-pressure mercury lamp at 400 mJ / cm 2 Pattern exposure was carried out, followed by development for 60 seconds in an aqueous solution of sodium carbonate at 1 wt%, a pressure of 0.2 MPa, and a liquid temperature of 30°C. Then, curing was performed at 150°C for 60 minutes in a hot air circulation drying oven to produce an evaluation substrate with a solder resist film. A rosin-based soldering flux was coated on the solder resist film of the evaluation substrate. The evaluation substrate coated with the rosin-based soldering flux was immersed in a solder bath pre-set at 288°C for 10 seconds, and then directly immersed in boiling water for 30 min, and the surface color was observed for whitening.

[0176] ○: No whitening

[0177] △: Slight whitening

[0178] ×: Severe whitening

[0179] As can be seen from the above, by adjusting the composition to that of Examples 1 to 4, an alkaline-developable resin composition with good printability (covering property, sag) and stability (tin resistance, resistance to whitening by boiling water) of the alkaline-developable resin composition can be obtained, and a solder mask alkaline-developable resin composition with excellent resistance to thermal shock, high-temperature storage stability, and acid resistance can be obtained. In contrast, in Comparative Example 1, only barium sulfate was used as the filler and talc was not used. In Comparative Examples 2 and 3, the proportion of talc in the filler was low, and no antioxidant was added. As a result, the resistance to thermal shock, high-temperature storage stability, and stability were all poor, and the printability was also poor. In Comparative Example 4, the proportion of talc was increased to 40 parts by weight. Although the stability (tin resistance, resistance to whitening by boiling water) tended to be improved, the resistance to thermal shock, high-temperature storage stability, and acid resistance were all poor, and the printability was also poor. In Comparative Example 5, an antioxidant was added on the basis of Comparative Example 4, improving the acid resistance and stability (tin resistance, resistance to whitening by boiling water), but the resistance to thermal shock and high-temperature storage stability were poor, and the printability was still poor. In Comparative Example 6, the total amount of the filler was increased on the basis of Comparative Example 5, improving the high-temperature storage stability, acid resistance, and stability (tin resistance, resistance to whitening by boiling water), and also improving some of the printability (sag), but the resistance to thermal shock and covering property were still poor. In the Reference Example, only talc was used as the filler on the basis of Comparative Example 5, with excellent printability (covering property, sag), and the resistance to thermal shock, high-temperature storage stability, and ink stability (tin resistance, resistance to whitening by boiling water) were all improved, but the acid resistance was poor.

Claims

1. An alkaline-developable resin composition, characterized in that, Comprising (A) a vinyl ester resin, (B) a photopolymerization initiator, (C) an antioxidant, (D) a compound having two or more ethylenically unsaturated groups in one molecule, and (E) an inorganic filler, wherein the (E) inorganic filler contains talc, and based on 100% by weight of the total amount of the (E) inorganic filler, the content of the talc is 50% by weight or more, and based on 100 parts by weight of the (A) vinyl ester resin in terms of solid content, the total content of the (E) inorganic filler is 60 to 180 parts by weight. Based on 100 parts by weight of the (A) vinyl ester resin in terms of solid content, the amount of the (C) antioxidant is 3 parts by weight or more.

2. The alkaline-developable resin composition according to claim 1, wherein It further contains (F) other additives in addition to the (B) photopolymerization initiator and the (C) antioxidant.

3. The basic developing type resin composition according to claim 1, characterized in that, It further contains (G) an epoxy resin.

4. The alkaline-developable resin composition according to claim 1, wherein It further contains (H) an organic solvent.

5. The alkaline-developable resin composition according to any one of claims 1 to 4, characterized in that The (E) inorganic filler further contains barium sulfate.

6. A photocurable dry film, characterized in that, It is obtained by coating the basic developing type resin composition according to any one of claims 1 to 5 on a carrier film and drying.

7. A cured product, characterized in that, It is obtained by photocuring the following coating film: a coating film obtained by coating the basic developing type resin composition according to any one of claims 1 to 5 on copper and drying; or a coating film obtained by coating the basic developing type resin composition on a carrier film and drying, and laminating the obtained photocurable dry film on copper.

8. A printed circuit board, characterized in that, It has a cured product obtained by thermally curing after photocuring the following coating film: a coating film obtained by coating the basic developing type resin composition according to any one of claims 1 to 5 on a substrate having a copper circuit and drying; or a coating film obtained by coating the basic developing type resin composition on a carrier film and drying, and laminating the obtained photocurable dry film on a substrate having a copper circuit.

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