JP6658801B2 - Method of forming resist pattern, permanent mask resist, and photosensitive resin composition - Google Patents

Description

  The present invention relates to a method for forming a resist pattern, a permanent mask resist, and a photosensitive resin composition.

  In recent years, as digital devices have become smaller and lighter, circuits formed on printed wiring boards, semiconductor package substrates, and flexible wiring boards have been miniaturized and densified. For the purpose of protecting these fine and high-density opening patterns, a solder resist having photosensitivity is used. The solder resist is required to have surface flatness, developability, high resolution, insulation reliability, solder heat resistance, gold plating resistance, and the like.

  As the photosensitive resin composition for a solder resist, a liquid photosensitive resin composition is usually used, particularly in the field of printed wiring boards. Then, a solder resist is formed from a two-part photosensitive resin composition in which a thermosetting epoxy resin and a photosensitive prepolymer containing a carboxyl group for imparting alkali developability are separately separated. General. As the photosensitive prepolymer, a photosensitive prepolymer which is obtained by adding an acrylic acid to a cresol novolak type epoxy resin and then modifying the resulting acid with an acid anhydride or the like, which can be alkali-developed, is widely used.

In the two-part photosensitive resin composition, the reaction between the epoxy resin and the carboxyl group of the photosensitive prepolymer proceeds even at room temperature, so that the storage stability (pot life) after mixing the two parts is several hours to one hour. There are restrictions on the conditions of use, such as short days and the need to mix immediately before use.
In order to avoid such a problem, conventionally, a one-pack type photosensitive resin composition having improved storage stability using a block-type isocyanate compound instead of an epoxy resin as a thermosetting agent has been used (for example, Patent Document 1). 1).

  On the other hand, in recent years, a photosensitive resin composition for a dry film type solder resist has been strongly desired from the viewpoint of improving the uniformity of film thickness, surface smoothness, thin film forming property, and handleability. According to such a photosensitive resin composition, in addition to the above-mentioned characteristics, effects such as simplification of a step for forming a solder resist and reduction of a solvent discharge amount at the time of forming a solder resist can be obtained.

  Until now, various dry film type photosensitive resin compositions for solder resist have been developed. For example, Patent Document 2 discloses a photosensitive film containing a polymer having a carboxyl group, a photopolymerizable compound, a photopolymerization initiator, and a bismaleimide compound. In Patent Document 3, a copolymer, a polymerizable compound and a photopolymer obtained by reacting 0.1 to 1.2 equivalents of a primary amine compound with an anhydride group of a maleic anhydride copolymer are disclosed. A photosensitive film containing an initiator is disclosed. Further, Patent Document 4 discloses a photosensitive film in which the contents of chlorine and hydrolyzable chlorine in both the photosensitive prepolymer and the epoxy resin are specified.

  On the other hand, as the diameter of the solder ball is reduced due to the narrow pitch of the connection terminals, the solder resist is further required to have a fine opening property (good resolution). In addition, with the narrowing of the pitch of the wiring, improvement of the embedding property and the HAST resistance is also strongly required.

JP 2001-305726 A JP 2004-287267 A JP 2005-316431 A JP 2009-265388 A

  However, when the photosensitive film described in the above-mentioned patent document is used, it is improved in all of the fine aperture, resolution, gold plating resistance, and HAST resistance (highly accelerated stress test, Highly Accelerated Temperature and Humidity Stress Test). There was room for In particular, the importance of the item of insulation reliability between fine wiring is increasing, and it is 130 ° C. in comparison with a test in which a voltage is applied at 85 ° C., 60% RH, or 85 ° C., 85% RH, which has been conventionally performed. , 85% RH, a high test temperature, and a resistance in a HAST test under severe conditions is required.

  The present invention relates to a photosensitive resin composition having excellent resolution, fine opening (circular hole resolution), gold plating resistance, solder resistance and HAST resistance, a method for forming a resist pattern using the same, and a method for forming the same. It is an object to provide the obtained permanent mask resist.

  The present inventors have conducted intensive studies on a one-pack type photosensitive resin composition using an epoxy resin as a thermosetting agent in order to solve the above-described problems. As a result, the chlorine content of the epoxy resin was reduced to a specific value or less. The inventors have found that the above object can be achieved by using the high-purity product obtained above and further treating the cleaning water used for forming the resist pattern with an aqueous solution containing divalent metal ions.

  The present invention provides [1] a resin having an ethylenically unsaturated group and a carboxyl group on a substrate, (b) a photopolymerizable monomer having an ethylenically unsaturated group, and (c) a photopolymerization initiator. And (d) an epoxy resin having a chlorine content of 500 ppm or less, and a photosensitive layer comprising a photosensitive resin composition containing the photosensitive resin composition. The present invention relates to a method for forming a resist pattern, which comprises removing the photosensitive layer region and performing treatment using an aqueous solution containing divalent metal ions.

Further, in the present invention, [2] the divalent metal ion is at least one metal ion selected from Ca ²⁺ , Mg ²⁺ , Sr ²⁺ , and Ba ^2+. And a method of forming a resist pattern.

  The present invention also relates to [3] a permanent mask resist produced by the method for forming a resist pattern according to [1] or [2].

Further, the present invention provides [4] providing a photosensitive layer made of a photosensitive resin composition on a substrate, curing a predetermined portion of the photosensitive layer with actinic rays, and removing the photosensitive layer region other than the predetermined portion. A photosensitive resin composition used in a method for forming a resist pattern, which is treated using an aqueous solution containing divalent metal ions,
(A) a resin having an ethylenically unsaturated group and a carboxyl group, (b) a photopolymerizable monomer having an ethylenically unsaturated group, (c) a photopolymerization initiator, and d) an epoxy resin having a chlorine content of 500 ppm or less.
Further, the present invention provides (I) a method comprising: (a) a resin having an ethylenically unsaturated group and a carboxyl group on a substrate; (b) a photopolymerizable monomer having an ethylenically unsaturated group; A photosensitive layer comprising a photosensitive resin composition containing an initiator and (d) a bisphenol A type epoxy resin having a chlorine content of 500 ppm or less is provided, and after curing a predetermined portion of the photosensitive layer with actinic light, The present invention relates to a method for forming a resist pattern, comprising removing the photosensitive layer region other than the predetermined portion and treating the photosensitive layer region with an aqueous solution containing divalent metal ions.
The present invention also provides [II], wherein the divalent metal ion is at least one metal ion selected from Ca ²⁺ , Mg ²⁺ , Sr ²⁺ , and Ba ^2+. And a method of forming a resist pattern.
Further, in the present invention, [III] a photosensitive layer made of a photosensitive resin composition is provided on a substrate, and after curing a predetermined portion of the photosensitive layer with actinic rays, the photosensitive layer region other than the predetermined portion is removed. A photosensitive resin composition used in a method for forming a resist pattern, which is treated using an aqueous solution containing a divalent metal ion, wherein the photosensitive resin composition comprises (a) an ethylenically unsaturated group and A resin having a carboxyl group, (b) a photopolymerizable monomer having an ethylenically unsaturated group, (c) a photopolymerization initiator, and (d) a bisphenol A type epoxy resin having a chlorine content of 500 ppm or less. And a photosensitive resin composition comprising:

  Using the photosensitive resin composition containing the high-purity epoxy resin of the present invention, exposure with a predetermined opening pattern, development with a dilute alkaline aqueous solution, treatment with an aqueous solution containing divalent metal ions, and curing By doing so, a resist pattern having excellent resolution, fine opening (round hole resolution), gold plating resistance, solder resistance, and HAST resistance can be formed. The permanent mask resist thus obtained has the same performance, and can form a solder resist optimal for a printed wiring board, a semiconductor package substrate, and a flexible wiring board.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In the present invention, (meth) acrylate means acrylate and methacrylate corresponding thereto, and (meth) acrylic acid means acrylic acid and methacrylic acid.

  The present invention provides (a) a resin having an ethylenically unsaturated group and a carboxyl group, (b) a photopolymerizable monomer having an ethylenically unsaturated group, (c) a photopolymerization initiator, and (d) a chlorine-containing monomer. Using a photosensitive resin composition containing a high-purity epoxy resin having an amount of 500 ppm or less, exposing the solder resist layer to a predetermined opening pattern, developing with a dilute alkaline aqueous solution, and then diluting an aqueous solution containing divalent metal ions. The present invention relates to a method for forming a resist pattern to be cured after being processed by using a resist.

  The main cause of the deterioration of the HAST resistance is largely due to impurity ions contained in the alkali development type solder resist layer. In particular, monovalent anions have a large ionization energy and tend to be carriers that carry ionized copper due to the voltage applied during the insulation test.

  In addition, sodium carbonate and potassium carbonate are generally used as a dilute alkali developer, but during the development step, monovalent sodium ions or potassium ions contained in these developers are taken into the solder resist layer. This is also considered to be a cause of the deterioration of the HAST resistance.

  Accordingly, the present inventors have conducted intensive studies and selected a high-purity epoxy resin having a chlorine content of 500 ppm or less in the above component (d), and exposed the solder resist layer with a predetermined opening pattern to obtain a rare resin. It has been found that HAST resistance can be improved by treating with an aqueous solution containing divalent metal ions after development with an alkaline aqueous solution.

<(A) component; a resin having an ethylenically unsaturated group and a carboxyl group>
Examples of the resin having an ethylenically unsaturated group and a carboxyl group as the component (a) of the present invention include, for example, an esterified product of an epoxy compound (a1) and an unsaturated monocarboxylic acid (a2), or a saturated or unsaturated polybasic acid. An addition reaction product to which the anhydride (a3) has been added can be used. These can be obtained by the following two-stage reaction.

  In the first reaction (hereinafter referred to as “first reaction” for convenience), the epoxy compound (a1) reacts with the unsaturated monocarboxylic acid (a2). In the next reaction (hereinafter referred to as “second reaction” for convenience), the esterified product produced in the first reaction reacts with the saturated or unsaturated polybasic acid anhydride (a3).

  The epoxy compound (a1) is not particularly limited, and examples thereof include a bisphenol epoxy compound, a novolak epoxy compound, a biphenyl epoxy compound, and a polyfunctional epoxy compound.

  As the bisphenol type epoxy compound, a compound obtained by reacting bisphenol A type or bisphenol F type with epichlorohydrin is suitable. Specifically, bisphenol A type, bisphenol F type, hydrogenated bisphenol A type, hydrogenated bisphenol A type, such as GY-260, GY-255, XB-2615, and Epicoat 828, 1007, 807, manufactured by Japan Epoxy Resin Co., Ltd. Epoxy compounds, such as alicyclic or polybutadiene-modified, are preferably used.

  As the novolak type epoxy compound, those obtained by reacting novolaks obtained by reacting phenol, cresol, halogenated phenols and alkylphenols with formaldehyde in the presence of an acidic catalyst and epichlorohydrin are suitable.

  Examples of the novolak type epoxy compound include, for example, YDCN-701, 704, YDPN-638, 602 manufactured by Toto Kasei Co., Ltd., DEN-431, 439 manufactured by Dow Chemical Company, EPN-1299 manufactured by Ciba Geigy, and N -730, 770, 865, 665, 673, VH-4150, 4240, Nippon Kayaku Co., Ltd. EOCN-120 and BREN.

  Examples of epoxy compounds having other structures include salicylaldehyde-phenol or cresol type epoxy compounds (Nippon Kayaku Co., Ltd., EPPN502H, FAE2500, etc.), DIC Corporation Epicron 840, 860, 3050, Dow Chemical. DER-330, 337, 361 manufactured by Daicel Chemical Industries, Ltd., Celloxide 2021, TETRAD-X, C manufactured by Mitsubishi Gas Chemical Co., Ltd., and EPB-13, 27 manufactured by Nippon Soda Co., Ltd. can also be used. These may be used alone or in combination of two or more, and a mixture or a block copolymer may be used.

  Examples of the unsaturated monocarboxylic acid (a2) include (meth) acrylic acid, crotonic acid, cinnamic acid, and a saturated or unsaturated polybasic acid anhydride and a (meth) acrylate having one hydroxyl group in one molecule. Or a reaction product of a half-ester compound of a saturated or unsaturated dibasic acid and an unsaturated monoglycidyl compound. Examples of the reactant include phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, succinic acid, and the like, and hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, tris (hydroxyethyl) isocyanurate, and the like. A reaction product obtained by reacting di (meth) acrylate, glycidyl (meth) acrylate, or the like with an equimolar ratio by a conventional method is exemplified. These unsaturated monocarboxylic acids can be used alone or as a mixture. Among these, acrylic acid is preferred.

  Examples of the saturated or unsaturated polybasic anhydride (a3) include succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, and hexahydrophthalic anhydride. , Methylhexahydrophthalic anhydride, ethylhexahydrophthalic anhydride, itaconic anhydride, trimellitic anhydride and the like.

  In the first reaction, a hydroxyl group is generated by an addition reaction between the epoxy group of the epoxy compound (a1) and the carboxyl group of the unsaturated monocarboxylic acid (a2). In the first reaction, the ratio of the epoxy compound (a1) to the unsaturated monocarboxylic acid (a2) is such that the ratio of the unsaturated monocarboxylic acid (a2) is 0.1 to 1 equivalent of the epoxy group of the epoxy compound (a1). The ratio is preferably 7 to 1.05 equivalents, and more preferably 0.8 to 1.0 equivalents.

  The epoxy compound (a1) and the unsaturated monocarboxylic acid (a2) can be dissolved in an organic solvent and reacted. As the organic solvent, for example, ethyl methyl ketone, ketones such as cyclohexanone, toluene, xylene, aromatic hydrocarbons such as tetramethylbenzene, methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, Glycol ethers such as dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate and carbitol acetate; and aliphatic carbons such as octane and decane. Hydrogens, petroleum ethers, petroleum solvents such as petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha can be used.

  In the first reaction, it is preferable to use a catalyst to promote the reaction. As the catalyst, for example, triethylamine, benzylmethylamine, methyltriethylammonium chloride, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyltrimethylammonium iodide, triphenylphosphine and the like can be used. The amount of the catalyst used is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the total of the epoxy compound (a1) and the unsaturated monocarboxylic acid (a2).

  In the first reaction, a polymerization inhibitor is used to prevent polymerization of the epoxy compounds (a1) or unsaturated monocarboxylic acids (a2) or the epoxy compound (a1) and the unsaturated monocarboxylic acid (a2). It is preferred to use. As the polymerization inhibitor, for example, hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol, and the like can be used. The amount of the polymerization inhibitor to be used is preferably 0.01 to 1 part by mass with respect to 100 parts by mass in total of the epoxy compound (a1) and the unsaturated monocarboxylic acid (a2). The reaction temperature of the first reaction is preferably from 60 to 150C, more preferably from 80 to 120C.

  In the first reaction, if necessary, an unsaturated monocarboxylic acid (a2) and a polybasic anhydride such as trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, biphenyltetracarboxylic anhydride, etc. And can be used in combination.

  In the second reaction, when the hydroxyl group generated in the first reaction and the hydroxyl group originally present in the epoxy compound (a1) undergo a half-ester reaction with the acid anhydride group of the saturated or unsaturated polybasic anhydride (a3). Inferred. Here, 0.1 to 1.0 equivalent of the polybasic acid anhydride (a3) can be reacted with 1 equivalent of the hydroxyl group in the resin obtained by the first reaction. By adjusting the amount of the polybasic acid anhydride (a3) within this range, the acid value of the component (a) can be adjusted.

  Examples of the resin having an ethylenically unsaturated group and a carboxyl group as described above include CCR-1218H, CCR-1159H, CCR-1222H, PCR-1050, TCR-1335H, ZAR-1035, ZAR-2001H, ZFR-1185, and ZCR- 1569H (all, manufactured by Nippon Kayaku Co., Ltd., trade name) and the like are commercially available.

  The resin having a carboxyl group and an ethylenically unsaturated group, which is the component (a) of the present invention, is an epoxy acrylate compound having an ethylenically unsaturated group and two or more hydroxyl groups (hereinafter, referred to as “raw epoxy acrylate”). It is preferable to use a polyurethane compound obtained by reacting a diisocyanate compound (hereinafter, referred to as “raw material diisocyanate”) with a diol compound having a carboxyl group (hereinafter, referred to as “raw material diol”).

  Examples of the raw material epoxy acrylate include compounds obtained by reacting (meth) acrylic acid with an epoxy compound such as a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, a novolak type epoxy compound, and an epoxy compound having a fluorene skeleton. No.

  As the raw material diisocyanate, any compound having two isocyanate groups can be used without any particular limitation. Such compounds include, for example, phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, diphenyl methane diisocyanate, naphthalene diisocyanate, triden diisocyanate, hexamethylene diisocyanate, dicyclohexyl methane diisocyanate, isophorone diisocyanate, allylene sulfone Examples include ether diisocyanate, allyl cyanisocyanate, N-acyl diisocyanate, trimethylhexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, and norbornane-diisocyanatemethyl. These can be used alone or in combination of two or more.

  The raw material diol is a compound having two hydroxyl groups and a carboxyl group in the molecule. Examples of the hydroxyl group include an alcoholic hydroxyl group and a phenolic hydroxyl group. From the viewpoint of improving the developability of the photosensitive resin composition with an aqueous alkali solution, the hydroxyl group is preferably an alcoholic hydroxyl group. Examples of such a raw material diol include dimethylolpropionic acid and dimethylolbutanoic acid.

  Examples of the polyurethane compound include a compound having a structural unit represented by the following general formula (3).

Here, in the general formula (3), R ¹⁰ represents a hydrogen atom or a methyl group, R ¹⁷ represents a residue of a raw material epoxy acrylate, R ¹⁸ represents a residue of a raw material diisocyanate, and R ¹⁹ represents a carbon atom having 1 carbon atom. 5 to 5 alkyl groups. The residue refers to the structure of a part obtained by removing a functional group provided for bonding from a raw material component. Specifically, as R ¹⁷ , for example, bis (4-oxyphenyl) -methane, 2,2-bis (4-oxyphenyl) -propane, 2,2-bis (4-oxyphenyl) -1, Examples thereof include bisphenol A type and bisphenol F type skeletons such as 1,1,3,3,3-hexafluoropropane, a novolak skeleton, a fluorene skeleton and the like. As R ¹⁸ , for example, phenylene, tolylene, xylylene, tetramethylxylylene Len, diphenylmethylene, hexamethylene, trimethylhexamethylene, dicyclohexylmethylene, isophorone and the like. Examples of the alkyl group having 1 to 5 carbon atoms for R ¹⁹ include a methyl group, an ethyl group, a propyl group, a butyl group, an isobutyl group, a pentyl group, and an amyl group.

  Note that a plurality of groups in the general formula (3) may be the same or different. When the terminal of the polyurethane compound is a hydroxyl group, the hydroxyl group may be treated with a saturated or unsaturated polybasic acid anhydride.

  Further, in the general formula (3), the structural unit derived from the raw material epoxy acrylate and the structural unit derived from the raw material diol have a structure in which they are alternately polymerized via the structural unit derived from the raw material diisocyanate. However, a structure in which a structural unit derived from a raw material epoxy acrylate and a structural unit derived from a raw material diol are polymerized blockwise via a structural unit derived from a raw material diisocyanate may be used.

The component (a), the general formula among the compounds represented by (3), the hard segment portions of the starting epoxy acrylate which is one of the main skeleton of the polyurethane, i.e., R ¹⁷ is, those of bisphenol A type structure is preferable. Such compounds are commercially available as UXE-3011, UXE-3012, UXE-3024 (manufactured by Nippon Kayaku Co., Ltd.) and the like. These can be used alone or in combination of two or more.

  Component (a) preferably has an acid value of 20 to 180 mgKOH / g, more preferably 30 to 150 mgKOH / g, and even more preferably 40 to 120 mgKOH / g. By setting the acid value in such a range, the developability of the photosensitive resin composition with an aqueous alkali solution can be improved, and the resolution can be improved.

  Here, the acid value can be measured by the following method. First, about 1 g of a measurement resin solution is precisely weighed, and then 30 g of acetone is added to the resin solution to uniformly dissolve the resin solution. Then, an appropriate amount of phenolphthalein as an indicator is added to the solution, and titration is performed using a 0.1 N aqueous KOH solution. Then, the acid value is calculated by the following equation (α).

  A = 10 × Vf × 56.1 / (Wp × I) (α)

  In the formula (α), A represents an acid value (mg KOH / g), Vf represents a titer (mL) of KOH, Wp represents a mass (g) of the measured resin solution, and I represents a nonvolatile content of the measured resin solution. (% By mass).

  Further, the weight average molecular weight of the component (a) is preferably from 3,000 to 30,000, more preferably from 5,000 to 20,000, further preferably from 7000 to 15,000, from the viewpoint of coating properties. These may be used alone or in combination of two or more resins having different molecular weights.

In this specification, the weight average molecular weight (Mw) refers to a value determined from a standard polystyrene conversion value by gel permeation chromatography (GPC). The measurement conditions in GPC are as follows.
Model: Hitachi L6000
Detection: L3300RI
Column: Gelpack GL-R440 + GL-R450 + GL-R400M
Column specification: diameter 10.7mm × 300mm
Solvent: THF
Sample concentration: 120 mg of a resin solution of NV (nonvolatile content) of 40% by mass was collected and dissolved in 5 mL of THF. Injection volume: 200 μL
Pressure: 49Kg · f / cm ²
Flow rate: 2.05 mL / min

<(B) component: a photopolymerizable monomer having an ethylenically unsaturated group>
In the present invention, the component (b) can be used without any particular limitation. However, in order to further improve the HAST resistance, a photopolymerizable monomer having an ethylenically unsaturated group and a tricyclodecane structure or a bisphenol A (meth) It is preferable to contain an acrylate compound.

  Examples of bisphenol A-based (meth) acrylate compounds include 2,2-bis (4-((meth) acryloxypolyethoxy) phenyl) propane and 2,2-bis (4-((meth) acryloxypolypropoxy). ) Phenyl) propane, 2,2-bis (4-((meth) acryloxypolybutoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypolyethoxypolypropoxy) phenyl) propane, etc. No.

  Examples of 2,2-bis (4-((meth) acryloxypolyethoxy) phenyl) propane include 2,2-bis (4-((meth) acryloxydiethoxy) phenyl) propane and 2,2-bis (4-((meth) acryloxydiethoxy) phenyl) propane Bis (4-((meth) acryloxypentaethoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypentadecaethoxy) phenyl), and the like, and 2,2-bis (4- (Methacryloxypentaethoxy) phenyl) propane is commercially available as BPE-500 (product name, manufactured by Shin-Nakamura Chemical Co., Ltd.) and FA-321M (product name, Hitachi Chemical Co., Ltd.). , 2-Bis (4- (methacryloxypentadecaethoxy) phenyl) is commercially available as BPE-1300 (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.). That. These can be used alone or in combination of two or more.

  In the present invention, it is preferable that a photopolymerizable monomer having an ethylenically unsaturated group and a tricyclodecane structure is included as the component (b).

  The photopolymerizable monomer having an ethylenically unsaturated group and a tricyclodecane structure is not particularly limited as long as it is a photopolymerizable monomer having a tricyclodecane structure.For example, dimethylol tricyclodecane diacrylate, dimethylol , Tricyclodecane dimethacrylate, tricyclodecanediol diacrylate and tricyclodecanediol dimethacrylate. Compounds corresponding to these are available as NK ester DCP and NK ester A-DCP (all manufactured by Shin-Nakamura Chemical Co., Ltd.).

  Further, the photopolymerizable monomer having an ethylenically unsaturated group and a tricyclodecane structure also preferably has a partial structure represented by the following general formula (1) or the following general formula (2).

［一般式（１）及び一般式（２）中、Ｒ^１、Ｒ^２は、直接結合、アルキレン、又はアリーレン基を示す。］

[In the general formulas (1) and (2), R ¹ and R ² represent a direct bond, an alkylene, or an arylene group. ]

  The alkylene group is preferably an alkylene group having 2 to 20 carbon atoms, more preferably an alkylene group having 2 to 10 carbon atoms, and further preferably an alkylene group having 2 to 6 carbon atoms.

  Examples of the alkylene group having 2 to 6 carbon atoms include an ethylene group, a propylene group, an isopropylene group, a butylene group, a pentylene group, and a hexylene group. Is preferable, and an ethylene group is particularly preferable.

  The arylene group is preferably an arylene group having 6 to 14 carbon atoms, and more preferably an arylene group having 6 to 10 carbon atoms. Examples of such an arylene group include phenylene and naphthylene.

  When a compound having a partial structure represented by the general formula (1) or (2) is used as the component (b), (b1) a diol compound having a tricyclodecane structure, and (b2) a diisocyanate A urethane compound obtained by reacting a compound with (b3) a compound having at least one ethylenically unsaturated group and one hydroxyl group in a molecule is preferable.

  The diisocyanate (b2) is not particularly limited, but is preferably a compound having a ring structure. Among them, those having a rigid structure such as isophorone diisocyanate are more preferable from the viewpoint of crack resistance (heat resistance).

  In addition, the compound having at least one or more ethylenically unsaturated groups and one hydroxyl group in the molecule (b3) may have two ethylenically unsaturated groups from the viewpoint of crosslinking density. Those having three are particularly preferred.

  Among them, the diisocyanate is isophorone diisocyanate, and in addition, the compound having at least one ethylenically unsaturated group and one hydroxyl group in the molecule is a compound represented by the general formula (2). Is more preferable. As such a compound, commercially available is UX-5002D-M20 (manufactured by Nippon Kayaku Co., Ltd.). These can be used alone or in combination of two or more.

  The use of a combination of a compound having no urethane bond in the molecule and a compound having a urethane bond in the molecule as the component (b) improves various properties required for the solder resist. Is preferred.

  Other components (b) include a compound obtained by reacting an α, β-unsaturated carboxylic acid with a polyhydric alcohol; a compound obtained by reacting an α, β-unsaturated carboxylic acid with a glycidyl group-containing compound; Examples include urethane monomers or urethane oligomers such as (meth) acrylate compounds having a urethane bond in the molecule. Other than these, nonylphenoxypolyoxyethylene acrylate; γ-chloro-β-hydroxypropyl-β ′-(meth) Phthalic acid-based compounds such as acryloyloxyethyl-o-phthalate and β-hydroxyalkyl-β ′-(meth) acryloyloxyalkyl-o-phthalate; alkyl (meth) acrylates, and ethylene oxide-modified nonylphenyl (meth) acrylate Etc. can be exemplified. These are used alone or in combination of two or more.

<(C) component: photopolymerization initiator>
The photopolymerization initiator (c) used in the present invention is not particularly limited as long as it matches the light wavelength of the exposure machine to be used, and a known one can be used. Specifically, for example, benzophenone, N, N'-tetraalkyl-4,4'-diaminobenzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-methyl- 1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 4,4'-bis (dimethylamino) benzophenone (Michler's ketone), 4,4'-bis (diethylamino) benzophenone, 4-methoxy-4 Aromatic ketones such as'-dimethylaminobenzophenone; benzyl derivatives such as benzyldimethyl ketal; 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (M-methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphene Nilimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2,4-di (p-methoxyphenyl) -5-phenylimidazole dimer, 2- (2,2 2,4-, 5-triarylimidazole dimer such as 4-dimethoxyphenyl) -4,5-diphenylimidazole dimer; acridine derivative such as N-phenylglycine, N-phenylglycine derivative, 9-phenylacridine; Oxime ester compounds such as 1,2-octanedione, 1- [4- (phenylthio)-, 2- (o-benzoyloxime)]; coumarin compounds such as 7-diethylamino-4-methylcoumarin; 2,4-diethyl Thioxanthone compounds such as thioxanthone; 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide Acylphosphine oxide compounds and the like. These may be used alone or in combinations of two or more.

Among these, it is preferable to use an aromatic ketone, and it is more preferable to use 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one.
When an aromatic ketone is used as the photopolymerization initiator (c), a thioxanthone compound is preferably contained as a sensitizer. Thereby, the opening shape can be made better.

  Examples of the thioxanthone compound include 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone. Among them, it is more preferable to include 2,4-diethylthioxanthone. 2,4-Diethylthioxanthone is commercially available as KAYACURE-DETX (product name, manufactured by Nippon Kayaku Co., Ltd.).

  It is also preferable to use a phosphine oxide compound from the viewpoint of improving the resist shape. Such compounds include, for example, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl)- 2,4,4-trimethyl-pentylphosphine oxide. Each of them is commercially available as DAROCURE-TPO and IRGACURE-819 (both manufactured by Ciba Japan KK).

  When a phosphine oxide compound is used as the photopolymerization initiator (c), it is preferable to further include a compound having an oxime ester for the purpose of improving sensitivity. Examples of the compound having the oxime ester include (2- (acetyloxyiminomethyl) thioxanthen-9-one), (1,2-octanedione, 1- [4- (phenylthio)-, 2- (o -Benzoyloxime)], ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (o-acetyloxime)). Commercial products include IRGACURE-OXE01 and IRGACURE-OXE02 (both manufactured by Ciba Specialty Chemicals).

<(D) component: an epoxy resin having a chlorine content of 500 ppm or less>
As the epoxy resin having a chlorine content of 500 ppm or less of the component (d) used in the present invention, a high-purity epoxy resin satisfying the above-mentioned chlorine content is used. Generally, an epoxy resin is obtained by reacting epichlorohydrin, but a treatment for removing chlorine or hydrolyzable chlorine generated as an impurity during the reaction by molecular distillation or the like is performed, and the content is small. is there.

  In order to reduce the chlorine content, (1) 1,2-propylene chlorohydrin, (2) 1,3-propylene chlorohydrin which is a side reaction, and (3) before epoxidation of (1) As a method of dehydrochlorinating an unreacted substance such as chloromethylation reacted with epichlorohydrin with an alkali hydroxide or the like to form an epoxy group, dissolving it in a solvent such as toluene, methyl isobutyl ketone, The reaction can be carried out by adding an aqueous solution of an alkali metal hydroxide such as potassium to ensure ring closure. In this case, the amount of the alkali metal hydroxide used is usually 0.01 to 0.3 mol, preferably 0.05 to 0.2 mol, per 1 mol of the hydroxyl group of the phenolic resin used for the epoxidation. The reaction temperature is usually 50 to 120 ° C, and the reaction time is usually 0.5 to 2 hours. After completion of the reaction, the generated salt is removed by filtration, washing with water, etc., and the solvent is distilled off under reduced pressure under heating. Further, the epoxy resin can be obtained by molecular distillation.

  Examples of commercially available epoxy resins include, for example, YD-8125, YDF-8170C, ZX-1059, YD-825GS, YDF-870GS, ZX-1658, and ZX-1627 (product names) which have been purified by molecular distillation. YX-8000, YX-8034 (product name, manufactured by Japan Epoxy Resin Co., Ltd.), N-655EXP-S, N-665EXP, N-670EXP-S, N-672EXP, N-685EXP. -S, (product name, manufactured by DIC Corporation), R140P, R140S, R140Q (product name, manufactured by Mitsui Chemicals, Inc.), ED-509S, ED-518S (manufactured by ADEKA Corporation), NC-3000H (product name, Nippon Kayaku Co., Ltd.).

  The epoxy resin used in the present invention may be of high purity, and is not limited to the above. Further, it is preferable to use the epoxy resin which is a solid at room temperature (25 ° C.) and has a softening point of 30 ° C. to 100 ° C., more preferably 50 ° C. to 100 ° C. Further, it is preferable to use a bisphenol F type epoxy resin from the viewpoint of various reliability.

  The content of each component in the photosensitive resin composition is 30 to 80 parts by weight of component (a) and 20 to 70 parts by weight of component (b) based on 100 parts by weight of the total of components (a) and (b). It is preferable that it becomes a part. More preferably, 40 to 75 parts by weight of the component (a) and 25 to 60 parts by weight of the component (b) are blended. Further, it is preferable that component (c) is incorporated in an amount of 0.1 to 30 parts by weight, preferably 0.1 to 20 parts by weight, and more preferably 0.1 to 10 parts by weight. Component (d) is preferably 3 to 50 parts by weight, more preferably 5 to 40 parts by weight. If the amount is too large, the HAST resistance may be degraded by the residual epoxy component, and if the amount is too small, sufficient cured film properties may not be obtained.

  In addition, the photosensitive resin composition used in the present invention may further contain other components according to desired characteristics in addition to the components (a) to (d) described above.

  Other components include the epoxy resin curing accelerator (e) as the component (e), but there is no particular limitation. For example, dicyandiamide, benzyldimethylamine, 4- (dimethylamino) -N, N-dimethylbenzylamine Amine compounds such as 4-methoxy-N, N-dimethylbenzylamine and 4-methyl-N, N-dimethylbenzylamine; quaternary ammonium salt compounds such as triethylbenzylammonium chloride; blocked isocyanate compounds such as dimethylamine; imidazole 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1- (2-cyanoethyl) -2-ethyl -4-methyli Imidazole derivatives such as dazole bicyclic amidine compounds and salts thereof; phosphorus compounds such as triphenylphosphine; guanamine compounds such as melamine, guanamine, acetoguanamine and benzoguanamine; 2,4-diamino-6-methacryloyloxyethyl-s-triazine 2-vinyl-2,4-diamino-s-triazine, 2-vinyl-4,6-diamino-s-triazine / isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxyethyl-s-triazine. S-Triazine derivatives such as isocyanuric acid adducts, boron trifluoride-amine complex, organic hydrazides, phthalic anhydride, trimellitic anhydride, ethylene glycol bis (anhydrotrimellitate), glycerol tris (anhydrotrimellitate) Tate , Aromatic acid anhydrides such as benzophenone tetracarboxylic anhydride, aliphatic acid anhydrides such as maleic anhydride, tetrahydrophthalic anhydride, polyphenols such as polyvinylphenol, polyvinylphenol bromide, phenol novolak, alkylphenol novolak, etc. Can be used.

Among these, dicyandiamide, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-vinyl-4,6-diamino-s-triazine / isocyanuric acid adduct and the like are preferable. These may be used alone or in combination of two or more.
The amount used is preferably 0.1 to 10% by mass based on 100 parts by mass of the total of the components (a) and (b).

  The photosensitive resin composition of the present invention, particularly when adhesion with a metal such as copper is required, as an adhesion improver, melamine, dicyandiamide, a triazine compound and its derivatives, imidazole, thiazole, triazole, silane Additives such as coupling agents can be used. For example, melamine, acetoguanamine, benzoguanamine, melamine-phenol-formalin resin, dicyandiamide, manufactured by Shikoku Chemicals; 2MZ-AZINE (2,4-diamino-6- [2'-methylimidazolyl- (1 ')]- Ethyl-s-triazine), 2E4MZ-AZINE (2,4-diamino-6- [2′-ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine), C11Z-AZINE (2, 4-diamino-6- [2'-undecylimidazolyl- (1 ')]-ethyl-s-triazine), 2MA-OK (2,4-diamino-6- [2'-methylimidazolyl- (1') ] -Ethyl-s-triazine isocyanuric acid adduct). Alternatively, triazine derivatives such as ethyldiamino-s-triazine, 2,4-diamino-s-triazine, and 2,4-diamino-6-xylyl-s-triazine are exemplified. These compounds improve the adhesion to the copper circuit, improve the PCT resistance, and are also effective in HAST resistance. These are preferably used in an amount of 0.1 to 10% by mass based on 100 parts by mass of the total of the components (a) and (b).

  Among these, it is preferable to include melamine or dicyandiamide, and it is more preferable to include both melamine or dicyandiamide.

  In the present invention, it is preferable to use an inorganic filler as needed for the purpose of improving properties such as adhesion and hardness. Examples of the inorganic filler include inorganic fillers such as barium sulfate, barium titanate, powdered silicon oxide, amorphous silica, talc, clay, calcined kaolin, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, and mica powder. Can be used. The use amount thereof is preferably 0 to 70% by mass based on the solid content of the photosensitive resin composition.

  In the present invention, it is desirable to use a diluting solvent as needed. Examples of the diluent include aliphatic alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, n-pentanol and hexanol; hydrocarbons such as benzyl alcohol and cyclohexane; diacetone alcohol; Aliphatic ketones such as 3-methoxy-1-butanol, acetone, methyl ethyl ketone, methyl propyl ketone, diethyl ketone, methyl isobutyl ketone, methyl pentyl ketone, methylhexyl ketone, ethyl butyl ketone, dibutyl ketone; ethylene glycol, diethylene glycol, triethylene Ethylene glycol, tetraethylene glycol, propylene glycol, ethylene glycol monoacetate, ethylene glycol diacetate, propylene glycol monoacetate, professional Ethylene glycol alkyl ethers such as len glycol diacetate, propylene glycol monoethyl ether, methyl cellosolve, ethyl cellosolve, butyl cellosolve, phenyl cellosolve, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, methyl cellosolve acetate, ethyl cellosolve acetate And its acetate, diethylene glycol monoalkyl ethers and their acetates, diethylene glycol dialkyl ethers, triethylene glycol alkyl ethers, propylene glycol alkyl ethers and their acetates, dipropylene glycol alkyl ethers, and toluene, petroleum ether, petroleum naphtha , Hydrogenated petroleum nuff Or petroleum solvents such as solvent naphtha, carboxylic acids such as ethyl formate, propyl formate, butyl formate, amyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate Esters, amines and amides such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide, dioxane, tetrahydrofuran, cyclohexanone, γ-butyrolactone, 3-hydroxy Solvents such as -2-butanone, 4-hydroxy-2-pentanone and 6-hydroxy-2-hexanone can be used alone or in combination of two or more.

  Further, if necessary, a coloring agent such as phthalocyanine blue, phthalocyanine green, iodine green, disazo yellow, malachite green, crystal violet, titanium oxide, carbon black, naphthalene black, or an azo organic pigment may be used. it can. Further, polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, tert-butylcatechol, pyrogallol, and phenothiazine; thixotropic agents such as bentone, montmorillonite, aerosil, and amide wax; silicone-based, fluorine-based, and polymer-based antifoaming agents And a leveling agent.

  When the diluent used in the present invention is applied to a support and used as a photosensitive film, it is preferably contained in a varnish state before application of 20 to 70% of the total mass. After that, after being formed into a film, it is preferable that the solvent content be 2% by mass or less in order to volatilize in a drying step at the time of film production.

Next, the photosensitive film will be described.
A photosensitive film obtained by using the photosensitive resin composition of the present invention includes a support, and a photosensitive resin composition layer formed of the photosensitive resin composition of the present invention formed on the support. It is. A protective film covering the photosensitive resin composition layer may be further provided on the photosensitive resin composition layer.

  The photosensitive resin composition layer is prepared by dissolving the photosensitive resin composition of the present invention in the above-mentioned solvent or mixed solvent to form a solution having a solid content of about 30 to 80% by mass, and then applying the solution on a support. Preferably, it is formed. The thickness of the photosensitive resin composition layer varies depending on the application, but is preferably 5 to 200 μm, more preferably 15 to 60 μm, after drying after removing the solvent by heating and / or hot air blowing. . If the thickness is less than 5 μm, it tends to be difficult to apply industrially, and if it exceeds 200 μm, the above-mentioned effects exerted by the present invention tend to be reduced, and in particular, the physical properties and resolution tend to be reduced.

  Examples of the support provided on the photosensitive film include a polymer film having heat resistance and solvent resistance, such as polyethylene terephthalate, polypropylene, polyethylene, and polyester.

  The thickness of the support is preferably from 5 to 100 μm, more preferably from 10 to 30 μm. If the thickness is less than 5 μm, the support tends to be broken when the support is peeled off before development, and if it exceeds 100 μm, the resolution and flexibility tend to decrease.

  The above-described photosensitive film composed of two layers of the support and the photosensitive resin composition layer or the photosensitive film composed of three layers of the support, the photosensitive resin composition layer and the protective film is stored, for example, as it is. Alternatively, it may be wound up in a roll around a core with a protective film interposed and stored.

  The method for forming a resist pattern using the photosensitive resin composition or the photosensitive film of the present invention first forms a resist by a known screen printing, a step of applying with a roll coater, or a step of attaching by lamination or the like. A photosensitive resin composition is laminated on a substrate. Next, if necessary, the support is removed from the above-described photosensitive film (generally, the support is provided without being removed, and the support is peeled off before the development step), and the actinic light is passed through a mask pattern. Then, an exposure step of irradiating a predetermined portion of the photosensitive resin composition layer with light and curing the irradiated portion of the photosensitive resin composition layer with light is performed. The photosensitive resin composition layer other than the irradiated part is removed in the next developing step. Note that a substrate on which a resist is formed refers to a printed wiring board, a substrate for a semiconductor package, or a flexible wiring board.

  As a light source of the actinic ray, a known light source, for example, a carbon arc lamp, a mercury vapor arc lamp, an ultra-high pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, or the like that effectively emits ultraviolet rays is used. In addition, those that effectively emit visible light, such as a flood light bulb for photography and a sun lamp, are also used. Further, a direct drawing type direct laser exposure may be used. By using the component (c) corresponding to each laser light source and exposure method, it becomes possible to form an excellent pattern.

  In the developing step, an alkali developing solution such as a dilute solution of sodium carbonate (0.1 to 10% by mass aqueous solution, preferably 1 to 5% by mass aqueous solution) at 20 to 50 ° C. is used as a developing solution. Developing by a known method such as rocking immersion, brushing, and scraping.

  As the alkali developer, for example, an aqueous alkali solution such as sodium hydroxide, potassium hydroxide, sodium silicate, ammonia, ethylamine, diethylamine, triethylamine, triethanolamine, and tetramethylammonium hydroxide (TMAH) is preferably used. The base concentration of these aqueous solutions is preferably 0.1 to 10% by mass. Further, an alcohol or a surfactant may be added to the above-mentioned developer for use. Each of these may be added in an amount of preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the developer.

In the developing step, the photosensitive layer is removed from the photosensitive layer except for the predetermined part, and the photosensitive layer is treated with an aqueous solution containing divalent metal ions, while leaving a predetermined part of the photosensitive layer hardened by irradiation with actinic rays. The divalent metal ions include Ca ²⁺ , Mg ²⁺ , Sr ²⁺ , Ba ²⁺ , Cd ²⁺ , Ni ²⁺ , Zn ²⁺ , Cu ²⁺ , Hg ²⁺ , Fe ²⁺ , Co ²⁺ , Sn ²⁺ , Pb ²⁺ , Mn ^{2+ and the} like. And at least one metal ion selected from Ca ²⁺ , Mg ²⁺ , Sr ²⁺ , and Ba ²⁺ . It is preferable to use Ca ²⁺ or Mg ²⁺ because the moisture-resistant insulation of the surface of the permanent mask resist is improved and the material is easily available. The divalent metal ion is obtained by dissolving and dispersing compounds such as sulfate, nitrate, chloride, acetate, carbonate, oxalate, phosphate, and hydroxide containing divalent metal ion in water. It is preferable to use them. If the basicity is strong, the photosensitive layer dissolves or peels off, and therefore the weak basicity is preferable. Sulfates, nitrates, chlorides, acetates, carbonates, oxalates, phosphates, etc. From the viewpoint of properties, nitrates and acetates are preferred.

  The metal ion concentration in the aqueous solution containing divalent metal ions is preferably 1 to 2000 ppm, more preferably 50 to 500 ppm, further preferably 50 to 500 ppm, and more preferably 50 to 350 ppm. Particularly preferred.

  At the time of the developing step, monovalent sodium ions and potassium ions contained in the developer are taken into the solder resist surface layer, and the taken-in monovalent cations form a 1: 1 ionic bond with the carboxylic acid. It is thought that there is. By substituting the monovalent cation with a divalent metal ion, the divalent metal ion can form a 1: 2 ionic bond with the carboxylic acid. Then, it is considered that the crosslinking on the surface of the solder resist is apparently improved, and the HAST resistance is improved. As described above, the HAST resistance can be improved by treating with an aqueous solution containing a divalent metal ion after development.

  The treatment with an aqueous solution containing divalent metal ions involves contacting the photosensitive resin composition layer on which a pattern has been developed and an aqueous solution containing divalent metal ions, by spraying the aqueous solution, Or by immersing the photosensitive resin composition layer in which the pattern is formed with the divalent metal ion. It is considered that the metal ions adsorbed on the surface of the photosensitive resin composition layer diffuse to some extent inside and are captured by the carboxylic acid in the composition as described above. The treatment temperature and time can be adjusted to 20 to 60 ° C., 5 seconds to 1 day, the contact temperature, the concentration of the aqueous solution, and the contact time to adjust the concentration of the metal ions that can be taken in. The longer the contact time, the higher the concentration of the metal ion taken in.

  The captured metal ions are, for example, scraped off 1 g of the permanent mask resist on the substrate, placed in a tetrafluoroethylene container together with 30 cc of pure water having an electric conductivity of 18 MΩ or more, and placed at 100 to 120 ° C. for 4 to 8 hours. A heat treatment is performed to thermally extract the ionic components. Thereafter, the sample subjected to the extraction treatment is returned to room temperature (25 ° C.). , Model Z5010, etc.) can be used to determine the metal cation component and concentration in the permanent mask resist. Further, by quantifying the concentration of the metal cation contained in the aqueous solution after the treatment by ion chromatography, the amount of the metal cation replaced by the treatment can be calculated.

After the development step and the treatment with the aqueous solution containing divalent metal ions, it is preferable to perform ultraviolet irradiation or heating using a high-pressure mercury lamp or the like for the purpose of improving solder heat resistance, chemical resistance, and the like. When irradiating with ultraviolet rays, the irradiation amount can be adjusted as needed, and for example, irradiation can be performed at an irradiation amount of about 0.2 to 10 J / cm ² . In addition, when heating the resist pattern, it is preferable to perform the heating at a temperature of about 100 to 170 ° C. for about 15 to 90 minutes. Further, ultraviolet irradiation and heating can be performed at the same time, and after performing one of them, the other can be performed. In the case where irradiation with ultraviolet rays and heating are performed simultaneously, it is more preferable to heat to 60 to 150 ° C. from the viewpoint of effectively imparting solder heat resistance, chemical resistance, and the like.

  After completion of the development step, washing with water, irradiation with ultraviolet rays and heating as described above, treatment with an aqueous solution containing divalent metal ions can be performed. Further, the treatment with the aqueous solution containing a divalent metal ion can be carried out again after the completion of the developing step and after irradiation with ultraviolet rays or heating. If necessary, washing or decomposition can be performed to remove extra metal ions attached to the surface of the photosensitive resin composition layer after the treatment.

  This photosensitive resin composition layer also serves as a protective film for wiring after soldering the substrate, and has good lamination temperature stability, excellent resolution, excellent flatness, crack resistance, HAST resistance, Since it has gold plating properties, it is effective as a solder resist for printed wiring boards, semiconductor package substrates, and flexible wiring boards.

  The substrate provided with the resist pattern in this manner is thereafter mounted with a semiconductor element or the like (for example, wire bonding or solder connection), and then mounted on an electronic device such as a personal computer.

  Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

(Preparation of photosensitive resin composition solution)
First, the photosensitive resin composition solution was obtained by mixing the components shown in Table 1 in the amounts (parts by mass) shown in the table. The following components were used as the components shown in Table 1.

<(A) component (resin having an ethylenically unsaturated group and a carboxyl group)>
"UXE-3024 (weight average molecular weight; 10,000)": urethane-modified epoxy acrylate (manufactured by Nippon Kayaku Co., Ltd.).
"UE-EXP-2810PM (weight average molecular weight; 10,000)": acid-modified cresol novolak type epoxy acrylate (manufactured by DIC Corporation).

<(B) component (photopolymerizable monomer having an ethylenically unsaturated group)>
"FA-321M": 2,2-bis (4- (methacryloxypentaethoxy) phenyl) propane (manufactured by Hitachi Chemical Co., Ltd.).
"NK Espel DCP": tricyclodecane dimethanol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.).
“UX-5002D-M20”: urethane acrylate containing a tricyclodecane structure (manufactured by Nippon Kayaku Co., Ltd.).

<(C) component (photopolymerization initiator)>
"DAROCURE-TPO": bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (manufactured by Ciba Specialty Chemicals).
"IRGACURE-OXE02": Ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime) (manufactured by Ciba Specialty Chemicals) ).
"IRGACURE-907": 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (manufactured by Ciba Specialty Chemicals).
"KATACURE-DETX-S": 2,4-diethylthioxanthone (product name, manufactured by Nippon Kayaku Co., Ltd.).

<(D) component (epoxy resin)>
"NC-3000H": molecular distilled product, bisphenol F type epoxy resin (total chlorine amount: 450 ppm, manufactured by Nippon Kayaku Co., Ltd., trade name).
"YD825GS": molecular distilled product, bisphenol A type epoxy resin (total chlorine amount 200 ppm, manufactured by Toto Kasei Co., Ltd., trade name).
"YX4000H": biphenyl type epoxy resin (total chlorine amount 1180 ppm, manufactured by Japan Epoxy Resin Co., Ltd., trade name).
“Epicoat 825”: bisphenol A type epoxy resin (standard product, total chlorine content 1880 ppm, manufactured by Japan Epoxy Resin Co., Ltd., trade name).

<Other components>
"Fine powder melamine": Melamine (trade name, manufactured by Nissan Chemical Industries, Ltd.).
"Dicyandiamide": "Epicure DICY7" (trade name, manufactured by Japan Epoxy Resin Co., Ltd.).
"Espel 1108": polyester-based elastomer (trade name, manufactured by Hitachi Chemical Co., Ltd.).
"Phthalocyanine blue": (trade name, manufactured by Toyo Ink Co., Ltd.).
"Variace B-30": A barium sulfate dispersion prepared using barium sulfate "Variace B-30" (trade name, manufactured by Sakai Chemical Industry Co., Ltd.) by the following method.

  (B) 20 parts by mass (solid content) of the component, 25 parts by mass of the above barium sulfate and 40 parts by mass of methyl ethyl ketone were subjected to a star mill LMZ (manufactured by Ashizawa Finetech Co., Ltd.) using zirconia beads having a diameter of 1.0 mm to obtain a peripheral speed. The dispersion was performed at 12 m / s for 3 hours to obtain a barium sulfate dispersion. Barium sulfate was incorporated in the photosensitive resin composition by blending the dispersion prepared above.

  In the photosensitive resin composition solutions of Examples and Comparative Examples, a mixed solution of methyl ethyl ketone and N, N-dimethylformamide at a mass ratio of 1: 1 as a diluent was used, and the solid content of the resin composition solution was 60% by mass. Was added.

  <Adjustment of aqueous solution>

Ca ²⁺ was selected as the divalent metal ion. Using calcium acetate (molecular weight = 158.14 (anhydrous), containing 25.34% by mass of calcium) as a supply source, 1.184 g of calcium acetate ((CH ₃ COO) ₂ Ca) in 1 liter of ion-exchanged water Was dissolved to prepare an aqueous solution containing 300 ppm of calcium ions.

In addition, ion-exchanged water containing no calcium ions was prepared.
[1.184 x 0.2534 / 1000 = 0.0003 (300 ppm)]

(Preparation of photosensitive film)
Next, the photosensitive resin composition solution obtained above is uniformly applied to a 16 μm-thick polyethylene terephthalate film (G2-16, manufactured by Teijin Limited, trade name) as a support, whereby the photosensitive resin composition is obtained. A material layer was formed, which was dried at 100 ° C. for about 10 minutes using a hot air convection dryer. The dried film thickness of the photosensitive resin composition layer was 25 μm.

  Subsequently, on the surface of the photosensitive resin composition layer opposite to the side in contact with the support, a polyethylene film (NF-15, trade name, manufactured by Tamapoly Co., Ltd.) is laminated as a protective film, A film (photosensitive element) was obtained.

(Characteristic evaluation of photosensitive film)
The following tests were performed using the photosensitive films of Examples 1 to 5 and Comparative Examples 1 to 4, respectively, and the resolution, opening shape, gold plating resistance, and solder heat resistance when each photosensitive element was used. , And HAST resistance. Table 2 shows the obtained results.

(Evaluation of resolution)
The copper surface of a printed wiring board (MCLE-679, manufactured by Hitachi Chemical Co., Ltd., trade name) in which a copper foil of 12 μm thickness was laminated on a glass epoxy substrate was polished with an abrasive brush, washed with water, and dried. . On this printed wiring board substrate, the polyethylene film of the photosensitive film was peeled off, and a vacuum pressurized laminator (2 stage type with flat press, MVLP-500, trade name, manufactured by Meiki Seisakusho Co., Ltd.) was used. Lamination was performed under the conditions of a compression pressure of 0.4 MPa, a hot press plate temperature of 80 ° C., a vacuum evacuation time of 20 seconds, a lamination press time of 30 seconds, and an air pressure of 4 kPa or less to obtain a laminate for evaluation.

  A phototool having a via diameter pattern in increments of 10 μm in the range of 30 to 100 μm as a negative was brought into close contact with the evaluation laminate, and a 41-step tablet was prepared using an EXM-1201 type exposure machine manufactured by Oak Manufacturing Co., Ltd. Exposure was performed at an energy amount such that the number of remaining steps after development was 16.0. Next, after leaving still at room temperature (25 ° C.) for 1 hour, the polyethylene terephthalate on the laminate was peeled off, spray-developed with a 1% by mass aqueous sodium carbonate solution at 30 ° C. for 60 seconds, and then washed with water (ion Exchange water or Ca ion aqueous solution, spray water washing for 120 seconds) to form a resist pattern.

  The formed resist pattern was observed with a stereoscopic microscope, the minimum opening via diameter was measured, and the resolution was determined. The smaller the value, the better the resolution. Table 2 shows the evaluation results.

(Evaluation of opening shape)
Using the substrate on which the resolution was evaluated, the cross-sectional shape of the formed resist pattern was observed and evaluated according to the following criteria. Table 2 shows the evaluation results.
"A": Solder resist hem or floating cannot be observed at the bottom of the opening.
"B": The bottom can be observed at the bottom of the opening.
“C”: Solder resist floating at the bottom of the opening can be observed.

(Evaluation of electroless Ni / Au plating resistance)
A plating resistance evaluation substrate was prepared in the same manner as in the evaluation laminate used for the above-described resolution evaluation. However, using a phototool having a via pattern with a diameter of 200 μm as a negative, the obtained resist pattern was irradiated with ultraviolet rays at an energy amount of 1 J / cm ² using an ultraviolet irradiation apparatus manufactured by Oak Manufacturing Co., Ltd. A laminate substrate for evaluation was obtained in which a solder resist having a via opening having a diameter of 200 μm was formed in the same manner except that the heat treatment was performed at 60 ° C. for 60 minutes. By the heating at this time, the calcium acetate adhering to the surface is decomposed into acetone and calcium carbonate.

  The laminate substrate for evaluation obtained above was subjected to electroless nickel plating (trade name: Nimden NPR-4, manufactured by Uemura Kogyo Co., Ltd.) (processing for 15 minutes), and further electroless gold plating (manufactured by Uemura Kogyo Co., Ltd.) (Trade name: Orical TKK-511) (15-minute treatment).

For the evaluation substrate plated in this way, the penetration of the plating solution into the bottom of the solder resist, and the lifting and peeling of the solder resist from the substrate were observed with a 100-fold metallographic microscope. The electroless Ni / Au plating resistance was evaluated. Table 2 shows the evaluation results.
“A”: No permeation into the solder resist bottom was observed.
"B": Those in which penetration into the solder resist bottom was 1 to 10 m.
"C": Other than the above.

(Evaluation of solder heat resistance)
An evaluation substrate for solder heat resistance was prepared in the same manner as in the evaluation laminate used in the above-described resolution evaluation. However, using a photo tool having a lattice pattern of 2 mm square as a negative, the obtained resist pattern was irradiated with ultraviolet light at an energy amount of 1 J / cm ² using an ultraviolet light irradiation device manufactured by Oak Manufacturing Co., Ltd. A laminate substrate for evaluation was obtained in which a solder resist having a 2 mm square grid pattern was formed in the same manner except that the heat treatment was performed at 60 ° C. for 60 minutes.

  Next, after applying a rosin-based flux (MH-820V, trade name, manufactured by Tamura Kaken Co., Ltd.) to the laminate substrate for evaluation obtained above, it was immersed in a 260 ° C. solder bath for 30 seconds to perform soldering. went.

By visually observing the degree of cracking of the solder resist on the evaluation board subjected to solder plating on the copper surface not covered with the resist and the degree of floating and peeling of the solder resist from the board, the following The solder heat resistance of the solder resist was evaluated according to the following criteria. Table 2 shows the evaluation results.
"O": No crack was observed in the solder resist, and no lifting or peeling of the solder resist was observed.
“×”: Any of the above is recognized.

[Evaluation of HAST resistance]
The copper surface of a printed wiring board (MCLE-679, manufactured by Hitachi Chemical Co., Ltd., trade name) in which a 12-μm-thick copper foil is laminated on a glass epoxy base material is etched to form a comb having a line / space of 50 μm / 50 μm by etching. A mold electrode was formed. Using this substrate as an evaluation substrate, a cured product of the resist (permanent resist film) was formed on the substrate as described above, and then tested at 130 ° C., 85% RH, and 5 V for 100 hours. Thereafter, the degree of migration was observed with a 100-fold metallographic microscope, and HAST resistance was evaluated based on the following criteria. Table 2 shows the evaluation results.
“○”: No significant migration occurred in the permanent resist film.
"X": Large migration occurred

  The methods of Examples 1 to 5 (d) using an epoxy resin having a chlorine content of 500 ppm or less and a method of forming a resist pattern treated with an aqueous solution containing a divalent metal ion are particularly excellent in HAST resistance. Also, it has excellent resolution, opening shape and gold plating resistance. When the amount of chlorine contained in the epoxy resin is large as in Comparative Examples 3 and 4, by washing with washing water containing divalent metal ions (Comparative Example 4), Comparative Example 3 was washed with ion-exchanged water. The resolution and the aperture shape tend to be improved as compared with the case of Further, even when the amount of chlorine contained in the epoxy resin is small as in Comparative Examples 1 and 2, washing with ordinary ion-exchanged water results in poor HAST resistance, poor resolution and poor opening shape. As described above, it is necessary to use an epoxy resin having a low chlorine content and to treat it with an aqueous solution containing a divalent metal ion.

  In the photosensitive resin compositions of Examples 1 to 5, FA-321M (tricyclodecane dimethanol dimethacrylate) and UX-5002D-M20 (tricyclodecane structure-containing urethane acrylate) were used in combination, and the characteristics were excellent. You can see that it is.

  According to the present invention, a solder resist that is excellent in resolution, opening shape, Ni / Au plating resistance, soldering heat resistance, and HAST resistance of a photosensitive solder resist, which is optimal for a printed wiring board, a semiconductor package substrate, and a flexible wiring board. Can be provided.

Claims (3)

On a substrate, (a) a resin having an ethylenically unsaturated group and a carboxyl group, (b) a photopolymerizable monomer having an ethylenically unsaturated group, (c) a photopolymerization initiator, and (d) chlorine-containing A photosensitive layer comprising a photosensitive resin composition containing a bisphenol A type epoxy resin having an amount of 500 ppm or less and (e) melamine and dicyandiamide, and curing a predetermined portion of the photosensitive layer with actinic light; A method for forming a resist pattern, comprising removing the photosensitive layer region other than a predetermined portion and treating the photosensitive layer region with an aqueous solution containing divalent metal ions. The method according to claim 1, wherein the divalent metal ion is at least one metal ion selected from Ca2 ⁺ , Mg2 ⁺ , Sr2 ⁺ , and Ba2 ⁺ . On a substrate, a photosensitive layer composed of a photosensitive resin composition is provided, and after curing a predetermined portion of the photosensitive layer with actinic rays, the photosensitive layer region other than the predetermined portion is removed and contains a divalent metal ion. Processing using an aqueous solution, a photosensitive resin composition used in a method of forming a resist pattern,
The photosensitive resin composition,
(A) a resin having an ethylenically unsaturated group and a carboxyl group, (b) a photopolymerizable monomer having an ethylenically unsaturated group, (c) a photopolymerization initiator, and (d) a chlorine content of 500 ppm or less. A photosensitive resin composition comprising: a bisphenol A type epoxy resin, and (e) melamine and dicyandiamide.