JP2011170049A - Solder resist composition and printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solder resist composition of high reflectance and high resolution while preventing a decrease in reflectance caused by discoloring deterioration, and a printed circuit board obtained by forming a solder resist using the solder resist composition. <P>SOLUTION: The solder resist composition contains (A) carboxyl group content resin not having an aromatic ring, (B) a bisacylphosphine oxide photopolymerization initiator, (C) a monoacylphosphine oxide photopolymerization initiator, (D) a photopolymerizable monomer, (E) rutile type titanium oxide, and (G) an organic solvent. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solder resist composition capable of forming a solder resist having a high reflectivity suitable for use as a permanent mask of a printed wiring board, and the solder resist composition on the surface of a printed wiring board on which a circuit is formed. The present invention relates to a printed wiring board in which a solder resist pattern is formed by using.

  In general, a printed wiring board is formed by removing unnecessary portions of a copper foil bonded to a laminated board by etching to form a circuit wiring, and electronic components are arranged at predetermined positions by soldering. In such a printed wiring board, a solder resist formed by applying and curing on a base material is used as a protective film for a circuit when soldering an electronic component.

  This solder resist prevents solder from adhering to unnecessary portions during soldering, and prevents the circuit conductor from being directly exposed to air and being deteriorated by oxygen or moisture. Furthermore, the solder resist also functions as a permanent protective film for the circuit board. Therefore, this requires various characteristics such as adhesion, electrical insulation, solder heat resistance, solvent resistance, and chemical resistance.

  In addition, printed wiring boards have been increasingly miniaturized (finer), multilayered, and one-boarded to achieve higher density, and the mounting method has also shifted to surface mounting technology (SMT). Therefore, demands for finer, higher resolution, higher accuracy, and higher reliability are increasing for solder resists.

  As a technique for forming such a solder resist pattern, a photolithography method capable of accurately forming a fine pattern is used, and an alkali development type photolithography method has become the mainstream, especially in consideration of environmental aspects. Yes.

  For example, in Patent Document 1 and Patent Document 2, development is possible with an aqueous alkali solution using a reaction product obtained by reacting a novolak epoxy resin with an unsaturated monocarboxylic acid and further adding a polybasic acid anhydride as a base polymer. A solder resist composition is disclosed.

  On the other hand, in recent years, light-emitting diodes (LEDs) that emit light at low power as backlights for liquid crystal displays of portable terminals, personal computers, televisions, etc., and light sources for lighting fixtures, etc. have been applied to printed wiring boards coated with solder resist. Applications for direct mounting are increasing.

  Therefore, in order to efficiently use the light of the LED, there is a demand for a printed wiring board in which the solder resist is white so that the solder resist has a high reflectance.

  However, since the white solder resist has a high reflectance, the composition itself reflects light at the time of patterning exposure and cannot sufficiently absorb the light necessary for curing, resulting in high resolution. As a result, it was difficult to form a high-definition pattern latent image.

  Moreover, the printed wiring board which mounted LED directly promotes deterioration and coloring of a white soldering resist with the light and heat which are emitted from LED, and causes a fall of a reflectance.

Japanese Patent Publication No. 1-54390 Japanese Patent Publication No. 7-17737

  An object of the present invention is to provide a solder resist composition and a printed wiring board for forming a solder resist film having high reflectivity and high resolution, which can efficiently use light from an LED.

  Furthermore, the objective of this invention is providing the soldering resist composition and printed wiring board which can prevent degradation and coloring of the soldering resist by the light and heat which are emitted from LED.

  As a result of diligent research, the present inventors have made use of a resin that does not have an aromatic ring as a carboxyl group-containing resin that enables alkali development and has a thermosetting property, and as a white pigment for achieving high reflectance, rutile. By using type titanium oxide, deterioration due to light and heat is suppressed for a long time, and a bisacylphosphine oxide photopolymerization initiator and a monoacylphosphine oxide photopolymerization initiator are used in combination as a photopolymerization initiator. Thus, it was found that even a solder resist composition containing a large amount of rutile-type titanium oxide having a high reflectivity can form a high-definition pattern latent image with excellent resolution.

  That is, the solder resist composition of the present invention comprises (A) a carboxyl group-containing resin having no aromatic ring, (B) a bisacylphosphine oxide photopolymerization initiator, and (C) a monoacylphosphine oxide photopolymerization start. Agent, (D) a photopolymerizable monomer, (E) rutile titanium oxide, and (G) an organic solvent, and further contains (F) an epoxy compound or (H) a thioxanthone photopolymerization sensitizer You can also

  According to the present invention, it has characteristics such as coating properties, photocurability, developability, solder heat resistance, adhesion, and electrical insulation required as a development type solder resist, and further, the reflectance is reduced and deteriorated over time. It is possible to form a solder resist film having a high reflectance and high resolution while suppressing coloring due to. Furthermore, the solder resist composition of the present invention can increase the illuminance as a whole when the LED is mounted on a printed wiring board.

It is a figure which shows the temperature of the heating furnace used for the light-proof and heat-resistant discoloration test of the test piece of an Example and a comparative example.

  Hereinafter, the present invention will be described in more detail.

  The solder resist composition of the present invention includes (A) a carboxyl group-containing resin having no aromatic ring, (B) a bisacylphosphine oxide photopolymerization initiator, and (C) a monoacylphosphine oxide photopolymerization initiator. , (D) a photopolymerizable monomer, (E) a rutile type titanium oxide, and (G) an organic solvent, and further comprising (F) an epoxy compound or (H) a thioxanthone photopolymerization sensitizer You can also

(Carboxyl group-containing resin having no aromatic ring)
Examples of the carboxyl group-containing resin (A) having no aromatic ring include a photosensitive carboxyl group-containing resin having one or more photosensitive unsaturated double bonds in itself, and a photosensitive unsaturated double bond. Any of the carboxyl group-containing resins that do not have can be used and is not limited to a specific one. In particular, among the resins listed below, those having no aromatic ring (any of oligomers or polymers) can be preferably used. That is, (1) a carboxyl group-containing resin obtained by copolymerization of an unsaturated carboxylic acid and a compound having an unsaturated double bond; (2) a carboxyl group-containing (meth) acrylic copolymer resin; A photosensitive carboxyl group-containing resin obtained by reacting a ring and a compound having an ethylenically unsaturated group; (3) a compound having one epoxy group and an unsaturated double bond in each molecule; A photosensitive carboxyl obtained by reacting a copolymer with a compound having a heavy bond with an unsaturated monocarboxylic acid, and reacting a secondary hydroxyl group produced by this reaction with a saturated or unsaturated polybasic acid anhydride. After reacting a group-containing resin and (4) a hydroxyl group-containing polymer with a saturated or unsaturated polybasic acid anhydride, each carboxylic acid produced by this reaction has 1 per molecule. The compounds are reacted with epoxy groups of the unsaturated double bond is a photosensitive hydroxyl and carboxyl group-containing resin obtained by.

  Among these, (a) the carboxyl group-containing (meth) acrylic copolymer resin (2), which is the photosensitive carboxyl group-containing resin of (2), and (b) an oxirane ring and an ethylenically unsaturated group in one molecule. A copolymer resin having a carboxyl group obtained by a reaction with a compound having an aromatic group is preferred.

  The carboxyl group-containing (meth) acrylic copolymer resin (a) is obtained by copolymerizing a (meth) acrylic acid ester and a compound having one unsaturated group and at least one carboxyl group in one molecule. Obtained. Examples of the (meth) acrylic acid ester constituting the copolymer resin (a) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl ( Hydroxyl groups such as (meth) acrylic acid alkyl esters such as (meth) acrylate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, caprolactone-modified 2-hydroxyethyl (meth) acrylate Containing (meth) acrylic acid esters, methoxydiethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, isooctyloxydiethylene glycol (meth) acrylate, phenoxy Triethylene glycol (meth) acrylate, methoxy triethylene glycol (meth) acrylate, glycol-modified (meth) acrylates such as methoxy polyethylene glycol (meth) acrylate. These may be used alone or in combination of two or more. In addition, in this specification, (meth) acrylate is a term that collectively refers to acrylate and methacrylate, and the same applies to other similar expressions.

  In addition, examples of the compound having one unsaturated group and at least one carboxyl group in one molecule include acrylic acid, methacrylic acid, and a modified unsaturated monocarboxylic acid in which a chain is extended between the unsaturated group and the carboxylic acid. For example, β-carboxyethyl (meth) acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, unsaturated monocarboxylic acid having an ester bond due to lactone modification, etc., modified unsaturated having an ether bond Examples thereof include monocarboxylic acids, and those containing two or more carboxyl groups in the molecule, such as maleic acid. These may be used alone or in combination of two or more.

  (B) The compound having an oxirane ring and an ethylenically unsaturated group in one molecule may be a compound having an ethylenically unsaturated group and an oxirane ring in one molecule. For example, glycidyl (meth) acrylate, α -Methyl glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylbutyl (meth) acrylate, 3,4-epoxycyclohexyl Examples include methylamino acrylate. Among these, 3,4-epoxycyclohexylmethyl (meth) acrylate is preferable. These (b) compounds having an oxirane ring and an ethylenically unsaturated group in one molecule may be used alone or in admixture of two or more.

  The carboxyl group-containing resin (A) not having an aromatic ring needs to have an acid value in the range of 50 to 200 mgKOH / g. When the acid value is less than 50 mgKOH / g, it is difficult to remove the unexposed portion of the coating film of the solder resist composition with a weak alkaline aqueous solution. When oxidation exceeds 200 mgKOH / g, there exists a problem that the water resistance of a cured film and an electrical property are inferior. Moreover, it is preferable that the weight average molecular weight of carboxyl group-containing resin (A) which does not have an aromatic ring exists in the range of 5,000-100,000. When the weight average molecular weight is less than 5,000, the dryness to touch of the coating film of the solder resist composition tends to be remarkably inferior. On the other hand, if the weight average molecular weight exceeds 100,000, it is not preferable because the developability and storage stability of the solder resist composition are remarkably deteriorated.

(Photopolymerization initiator)
(Bisacylphosphine oxide photopolymerization initiator)
Examples of the bisacylphosphine oxide photopolymerization initiator (B) used in the present invention include bis- (2,6-dichlorobenzoyl) phenylphosphine oxide and bis- (2,6-dichlorobenzoyl) -2,5. -Dimethylphenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -4-propylphenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -1-naphthylphosphine oxide, bis- (2,6 -Dimethoxybenzoyl) phenylphosphine oxide, bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis- (2,6-dimethoxybenzoyl) -2,5-dimethylphenylphosphine Fin oxide, bis- (2,4,6-tri Chirubenzoiru) phenyl phosphine oxide, (2,5,6-trimethylbenzoyl) -2,4,4-trimethylpentyl phosphine oxide and the like. Among them, bis- (2,4,6-trimethylbenzoyl) phenylphosphine oxide (manufactured by Ciba Japan, trade name; Irgacure 819) is easily available and practical.

(Monoacylphosphine oxide photopolymerization initiator)
Examples of the monoacylphosphine oxide photopolymerization initiator (C) used in the present invention include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, and 2,6-dichloro. Examples include benzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphinic acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, and pivaloylphenylphosphinic acid isopropyl ester. Among them, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by Ciba Japan, trade name: Darocur TPO) is easily available and practical.

  The solder resist composition of the present invention is a combination of titanium oxide by combining the bisacylphosphine oxide photopolymerization initiator (B) and the monoacylphosphine oxide photopolymerization initiator (C). Even a reflective coating film can absorb necessary light, and a high-definition pattern can be formed. Moreover, the light absorption of the coating film can be finely adjusted by changing the blending ratio. That is, when the cross-sectional shape of the pattern is insufficient in curability at the deep part on the substrate surface side and undercut is likely to occur, the ratio of the bisacylphosphine oxide photopolymerization initiator (B) is increased. When the surface curability is insufficient and the surface condition is poor after development, the ratio of the monoacylphosphine oxide photopolymerization initiator (C) is increased. The blending ratio of the bisacylphosphine oxide photopolymerization initiator (B) to the monoacylphosphine oxide photopolymerization initiator (C) is 90:10 to 1:99, preferably 80:20 to 2:98. It is. Outside the range of this blending ratio, the effect of the combined use is reduced, and the necessary light cannot be absorbed, so that a high-definition pattern cannot be formed.

  The total amount of the bisacylphosphine oxide photopolymerization initiator (B) and the monoacylphosphine oxide photopolymerization initiator (C) is 100 parts by mass of the carboxyl group-containing resin (A) having no aromatic ring. The amount is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass. When the total blending amount of the bisacylphosphine oxide photopolymerization initiator (B) and the monoacylphosphine oxide photopolymerization initiator (C) is less than 1 part by mass, the photocurability decreases, and exposure / development Since subsequent pattern formation becomes difficult, it is not preferable. On the other hand, when the total blending amount exceeds 30 parts by mass, the color of the coating film derived from the photopolymerization initiator is increased, and the cost is increased.

(Photopolymerizable monomer)
Examples of the photopolymerizable monomer (D) used in the present invention include hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxybutyl acrylate; glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, and propylene glycol. Mono- or diacrylates; acrylamides such as N, N-dimethylacrylamide and N-methylolacrylamide; aminoalkyl acrylates such as N, N-dimethylaminoethyl acrylate; hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol Polyhydric alcohols such as tris-hydroxyethyl isocyanurate or their ethylene oxide or propylene oxide Polyvalent acrylates; phenoxy acrylate, bisphenol A diacrylate and acrylates such as ethylene oxide or propylene oxide adducts of these phenols; glycidyl ether acrylates such as glycerin diglycidyl ether and trimethylolpropane triglycidyl ether Melamine acrylate; and / or methacrylates corresponding to the above acrylates.

  The blending amount of these photopolymerizable monomers (D) is preferably 10 to 100 parts by mass, more preferably 20 to 80 parts by mass with respect to 100 parts by mass of the carboxyl group-containing resin (A) having no aromatic ring. It is. When the blending amount exceeds 100 parts by mass, the physical properties of the cured coating film as a solder resist are lowered, which is not preferable. On the other hand, when the blending amount is less than 10 parts by mass, sufficient photocurability is not obtained and a high-definition pattern cannot be obtained.

(Rutile titanium oxide)
In the present invention, rutile type titanium oxide (E) is used as the white pigment. Common titanium oxide includes anatase type and rutile type. Since anatase type titanium oxide has photocatalytic activity, it may cause discoloration of the resin in the solder resist composition. In contrast, rutile-type titanium oxide absorbs near the boundary between the ultraviolet region and the visible light region as compared to anatase-type titanium oxide, and is inferior in terms of whiteness and reflectivity of the entire visible light region, but photoactive Therefore, a stable solder resist film can be obtained.

  A well-known thing can be used as said rutile type titanium oxide (E). Specifically, the Taipei R-820, the Taipei R-830, the Taipei R-930, the Taipei R-550, the Taipei R-630, the Taipei R-680, the Taipei R-670, the Taipei R-680, the Taipei R-670, Type R-780, Type R-850, Type CR-50, Type CR-57, Type CR-80, Type CR-90, Type CR-93, Type CR-95, Type CR-97, Type CR CR-60, Taipei CR-63, Taipei CR-67, Taipei CR-58, Taipei CR-85, Taipei UT771 (manufactured by Ishihara Sangyo Co., Ltd.), Taipei Pure R-100, Taipei Pure R-101, Taiwan Pure R-102, Taiwan Pure R-103, Tai Pure R-1 4, Tai Pure R-105, Tai Pure R-108, Tai Pure R-900, Tai Pure R-902, Tai Pure R-960, Tai Pure R-706, Tai Pure R-931 (manufactured by DuPont), TITON R-25, TITON R -21, TITON R-32, TITON R-7E, TITON R-5N, TITON R-61N, TITON R-62N, TITON R-42, TITON R-45M, TITON R-44, TITON R-49S, TITON GTR -100, TITON GTR-300, TITON D-918, TITON TCR-29, TITON TCR-52, TITON FTR-700 (manufactured by Sakai Chemical Industry Co., Ltd.) and the like can be used.

  The amount of such rutile-type titanium oxide (E) is preferably 50 to 450 parts by weight, more preferably 60 to 350 parts by weight with respect to 100 parts by weight of the carboxyl group-containing resin (A) having no aromatic ring. Part. If the blending amount exceeds 450 parts by mass, the photocurability is lowered, and the curing depth is lowered, which is not preferable. On the other hand, when the blending amount is less than 50 parts by mass, the hiding power is small and a high reflectance solder resist cannot be obtained.

(Epoxy compound)
Next, as the epoxy compound (F), for example, bisphenol S type epoxy resin, diglycidyl phthalate resin, triglycidyl isocyanurate (for example, 3 TEPIC-H (manufactured by Nissan Chemical Co., Ltd. with respect to the S-triazine ring skeleton surface) Β-epoxies having a structure in which the epoxy groups are bonded in the same direction) and TEPIC (β-bonding, and one epoxy group bonded to the other two epoxy groups in the S-triazine ring skeleton plane) Etc.)), etc., etc.), etc.), etc.), etc.), etc. A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type resin, brominated bisphenol Type epoxy resin, phenol novolac type or cresol novolac type epoxy resin, alicyclic epoxy resin, bisphenol A novolac type epoxy resin, chelate type epoxy resin, glyoxal type epoxy resin, amino group-containing epoxy resin, rubber-modified epoxy resin, di Examples thereof include epoxy resins that are soluble in diluents such as cyclopentadiene phenolic epoxy resins, silicone-modified epoxy resins, and ε-caprolactone-modified epoxy resins. These epoxy resins can be used alone or in combination of two or more.

  The compounding amount of such an epoxy compound (F) is preferably 5 to 70 parts by mass, more preferably 5 to 60 parts by mass with respect to 100 parts by mass of the carboxyl group-containing resin (A) having no aromatic ring. . When the compounding quantity of an epoxy compound (F) exceeds 70 mass parts, the solubility of the unexposed part in a developing solution will fall, it will become easy to generate | occur | produce the image development residue, and it is difficult to use it practically. On the other hand, if the blending amount is less than 5 parts by mass, the carboxyl group of the carboxyl group-containing resin (A) having no aromatic ring remains in an unreacted state. The chemical resistance tends to be difficult to obtain sufficiently.

  The carboxyl group of the carboxyl group-containing resin (A) not having an aromatic ring and the epoxy group of the epoxy compound (F) react by ring-opening polymerization. And when an easily soluble epoxy resin is used as the organic solvent (G) or other substance in the solder resist composition, the crosslinking of the carboxyl group and the epoxy group easily proceeds due to heat during drying. Therefore, when it is desired to suppress the crosslinking reaction and increase the drying time, it is desirable to use a hardly soluble epoxy resin alone or together with a readily soluble epoxy resin.

(Organic solvent)
(G) used by this invention is used in order to make a soldering resist composition easy to apply | coat, and after applying this to a base material etc. and drying, it forms a coating film. Examples of the organic solvent (G) include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, Glycol ethers such as propylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, cellosolve acetate, diethylene glycol monoethyl ether acetate and esters of the above glycol ethers Esters such as compounds; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol Le acids; can be exemplified petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, a petroleum solvent or the like, such as solvent naphtha; octane, aliphatic hydrocarbons such as decane.

  The organic solvent (G) can be used alone or as a mixture of two or more. As for the compounding quantity of an organic solvent (G), 20-300 mass parts is preferable with respect to 100 mass parts of carboxyl group-containing resin (A) which does not have an aromatic ring.

(Thioxanthone photopolymerization sensitizer)
In the present invention, it is desirable to blend a thioxanthone photopolymerization sensitizer (H) for the purpose of improving the sensitivity to light during exposure. In the composition in which the bisacylphosphine oxide photopolymerization initiator (B) and the monoacylphosphine oxide photopolymerization initiator (C) are used in combination, the effect of the thioxanthone photopolymerization sensitizer (H) is very high. Because it is expensive. As this thioxanthone photopolymerization sensitizer (H), thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropyl Examples include thioxanthone.

  The amount of such a thioxanthone photopolymerization sensitizer (H) is preferably 0.05 to 2 parts by mass, more preferably 0 with respect to 100 parts by mass of the carboxyl group-containing resin (A) having no aromatic ring. .1 to 1 part by mass. When the blending amount is less than 0.05 parts by mass, the effect of improving the sensitivity is small, and when it exceeds 2 parts by mass, coloring of the coating film derived from thioxanthone increases.

(Other ingredients)
(Stabilizer)
Furthermore, in the solder resist composition of this invention, photodegradation can be reduced by including a hindered amine light stabilizer.

  As a hindered amine light stabilizer, for example, Tinuvin 622LD, Tinuvin 144; CHIMASSORB 944LD, CHIMASSORB 119FL (all manufactured by Ciba Japan Co., Ltd.); LA-68 (all manufactured by ADEKA Corporation); Sanol LS-770, LS-765, LS-292, LS-2626, LS-1114, LS-744 (all manufactured by Sankyo Lifetech Co., Ltd.) Can be mentioned.

  The light stabilizer is preferably added in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the carboxyl group-containing resin (A) having no aromatic ring.

(Dispersant)
In the solder resist composition of the present invention, the dispersibility and sedimentation of titanium oxide can be improved by containing a dispersant. Examples of the dispersing agent include, for example, ANTI-TERRA-U, ANTI-TERRA-U100, ANTI-TERRA-204, ANTI-TERRA-205, DISPERBYK-101, DISPERBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-108. DISPERBYK-109, DISPERBYK-110, DISPERBYK-111, DISPERBYK-112, DISPERBYK-116, DISPERBYK-130, DISPERBYK-140, DISPERBYK-142, DISPERBYK-145, DISPERBYK-161, DISPERBY63-62 -164, DISPERBYK- 66, DISPERBYK-167, DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-180, DISPERBYK-182, DISPERBYK-183, DISPERBYK-185, DISPERBYK-184, DISPERBYK-184, DISPERBYK-2009, DISPERBYK-2020, DISPERBYK-2025, DISPERBYK-2050, DISPERBYK-2070, DISPERBYK-2096, DISPERBYK-2150, BYK-P104, BYK-P104S, BYK-P105, BYK-P105, BYK-P105, BYK-P105 220S Manufactured by Big Chemie Japan Co., Ltd.), Dispalon 2150, Disparon 1210, Disparon KS-860, Disparon KS-873N, Disparon 7004, Disparon 1830, Disparon 1860, Disparon 1850, Disparon DA-400N, Disparon PW-36, Disparon DA-703 -50 (made by Enomoto Kasei Co., Ltd.), florene G-450, florene G-600, florene G-820, florene G-700, florene DOPA-44, florene DOPA-17 (manufactured by Kyoeisha Chemical Co., Ltd.).

  The content of the dispersant is 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of rutile-type titanium oxide (E) in order to effectively achieve the above object. preferable.

(Other additive components)
Furthermore, in the solder resist composition of the present invention, a curing accelerator, a thermal polymerization inhibitor, a thickener, an antifoaming agent, a leveling agent, a coupling agent, a flame retardant aid and the like can be used as necessary.

(Manufacturing method)
As an example of the use of the solder resist composition, the production of a printed wiring board will be described below.

  First, the solder resist composition of the present invention is diluted as necessary to adjust the viscosity to be suitable for the coating method.

  Next, the viscosity-adjusted composition is applied to a printed wiring board on which a circuit has been formed by a method such as screen printing, curtain coating, spray coating, or roll coating. And a tack-free coating film is formed by evaporating and drying the organic solvent contained in the applied composition at a temperature of 70 to 90 ° C., for example.

  Thereafter, the coating film is selectively exposed with active energy rays through a photomask, and the unexposed portion is developed with an alkaline aqueous solution to form a resist pattern. And this solder resist pattern is formed by thermosetting this resist pattern at 100 to 200 degreeC.

  As an irradiation light source for exposure, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a metal halide lamp, or the like can be used. In addition, a laser beam can also be used as an actinic beam.

  As the alkaline aqueous solution that is a developer, a 0.5 to 5% by mass aqueous sodium carbonate solution is common. It is also possible to use other alkaline aqueous solutions. Examples of other alkaline aqueous solutions include alkaline aqueous solutions such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium phosphate, sodium silicate, ammonia, amines and the like.

  And after forming a soldering resist pattern, LED is mounted and the printed wiring board which concerns on this invention is manufactured. Such a printed wiring board according to the present invention is manufactured using the solder resist containing titanium oxide having high reflectivity according to the present invention, and has a high reflectivity and high definition pattern.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, it cannot be overemphasized that this invention is not limited to this.

(A) Synthesis of carboxyl group-containing resin having no aromatic ring Synthesis Example 1
In a 2 liter separable flask equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel and a nitrogen introducing tube, 900 g of diethylene glycol dimethyl ether as a solvent and t-butylperoxy 2-ethylhexanoate (NOF) as a polymerization initiator 21.4 g, manufactured by Co., Ltd., trade name: Perbutyl O) was added and heated to 90 ° C. After heating, 309.9 g of methacrylic acid, 116.4 g of methyl methacrylate, and 109.8 g of lactone-modified 2-hydroxyethyl methacrylate (manufactured by Daicel Chemical Industries, Ltd., trade name: Plaxel FM1) were used as a polymerization initiator. Along with 21.4 g of a certain bis (4-t-butylcyclohexyl) peroxydicarbonate (manufactured by NOF Corporation, trade name: Parroyl TCP), it was added dropwise over 3 hours. Further, this was aged for 6 hours to obtain a carboxyl group-containing copolymer resin. These reactions were performed in a nitrogen atmosphere.

  Next, 363.9 g of 3,4-epoxycyclohexylmethyl acrylate (trade name; Cyclomer A200, manufactured by Daicel Chemical Industries, Ltd.) and 3.6 g of dimethylbenzylamine as a ring-opening catalyst were added to the obtained carboxyl group-containing copolymer resin. Then, 1.80 g of hydroquinone monomethyl ether was added as a polymerization inhibitor, heated to 100 ° C., and stirred to carry out an epoxy ring-opening addition reaction. After 16 hours, a solution containing 53.8% by mass (nonvolatile content) of a carboxyl group-containing resin having no aromatic ring and having an acid value of solid content of 108.9 mgKOH / g and a weight average molecular weight of 25,000 was obtained. . Hereinafter, this reaction solution is referred to as A-1 varnish.

Synthesis example 2
In a flask equipped with a thermometer, a stirrer, a dropping funnel, and a reflux condenser, diethylene glycol monoethyl ether acetate as a solvent and azobisisobutyronitrile as a catalyst are heated to 80 ° C. in a nitrogen atmosphere. A monomer in which acrylic acid and methyl methacrylate were mixed at a molar ratio of 0.40: 0.60 was added dropwise over about 2 hours. Furthermore, after stirring this for 1 hour, the temperature was raised to 115 ° C. and deactivated to obtain a resin solution.

  After cooling the resin solution, tetrabutylammonium bromide was used as a catalyst, and butyl glycidyl ether was added at a molar ratio of 0.40 at 95 to 105 ° C. for 30 hours. Addition reaction with an equal volume and cooling.

  Furthermore, tetrahydrophthalic anhydride was subjected to addition reaction at a molar ratio of 0.26 under the condition of 95 to 105 ° C. for 8 hours with respect to the OH group of the resin obtained above. This was taken out after cooling to obtain a solution containing 50% by mass (non-volatile content) of a carboxyl group-containing resin having an aromatic ring with a solid content of 78.1 mgKOH / g and a weight average molecular weight of 35,000 and having no aromatic ring. . Hereinafter, this reaction solution is called A-2 varnish.

Synthetic comparison synthesis example 1 of carboxyl group-containing resin having aromatic ring
In a flask equipped with a thermometer, a stirrer, a dropping funnel, and a reflux condenser, 210 g of cresol novolac type epoxy resin (Epiclon N-680 manufactured by DIC Corporation, epoxy equivalent = 210) and carbitol acetate 96. 4 g was added and dissolved by heating. Subsequently, 0.1 g of hydroquinone as a polymerization inhibitor and 2.0 g of triphenylphosphine as a reaction catalyst were added thereto. This mixture was heated to 95-105 ° C., 72 g of acrylic acid was gradually added dropwise, and the mixture was reacted for about 16 hours until the acid value became 3.0 mgKOH / g or less. The reaction product was cooled to 80 to 90 ° C., 76.1 g of tetrahydrophthalic anhydride was added, and the infrared absorption analysis showed about 6 until the acid anhydride absorption peak (1780 cm −1) disappeared. Reacted for hours. To this reaction solution, 96.4 g of aromatic solvent ipsol # 150 manufactured by Idemitsu Kosan Co., Ltd. was added, diluted and taken out. The thus obtained carboxyl group-containing photosensitive polymer solution had a nonvolatile content of 65% by weight and a solid acid value of 78 mgKOH / g. Hereinafter, this reaction solution is referred to as B-1 varnish.

Formulation of Examples 1-5 and Comparative Examples 1-5:
Each component was blended according to Table 1, stirred, and dispersed with a three roll to prepare solder resist compositions. The numbers in the table indicate parts by mass.

Photopolymerization initiator A1: Bis- (2,4,6-trimethylbenzoyl) phenylphosphine oxide Irgacure 819 (manufactured by Ciba Japan)
Photopolymerization initiator A2: 2,4,6-trimethylbenzoyldiphenylphosphine oxide Darocure TPO (manufactured by Ciba Japan)
Photopolymerization initiator B1: Irgacure 907 (Ciba Japan)
Photopolymerizable monomer: Dipentaerythritol hexaacrylate titanium oxide A: Rutile titanium oxide CR-95 (manufactured by Ishihara Sangyo Co., Ltd.)
Titanium oxide B: Anatase type titanium oxide A-220 (Ishihara Sangyo Co., Ltd.)
Epoxy compound: TEPIC-H (Nissan Chemical Co., Ltd.)
Thermosetting accelerator: Dicyandiamide sensitizer: 2,4-diethylthioxanthone Kayacure DETX-S (manufactured by Nippon Kayaku Co., Ltd.)
Solvent: Carbitol acetate antifoaming agent (silicone oil): KS-66 (manufactured by Shin-Etsu Chemical)
In order to examine various properties of the solder resist formed using each solder resist composition, the following tests and evaluations were performed.

(1) Resolution (cross-sectional shape)
Each solder resist composition was 100 mm × 150 mm in size and 1.6 mm thick on an FR-4 copper-clad laminate using a screen printing method using a 100 mesh polyester (made by Bias) plate. It was printed with a solid (entire substrate surface). This was dried at 80 ° C. for 10 minutes in a hot air circulating drying oven. Further, a solder resist composition was printed on each of the dried coating films in the same manner as described above, and dried at 80 ° C. for 20 minutes in a hot air circulation type drying furnace. Furthermore, using an exposure machine HMW-680GW for printed wiring board (manufactured by Oak Manufacturing Co., Ltd.), using a mask pattern of a line with a negative dimension of 250 μm, Examples 1 and 2 and Comparative Examples 1 to 3 and 5 the 450 mJ / cm ^2, example 3 and 4, in the integrated light quantity of 900 mJ / cm ² for Comparative example 4 was exposed to ultraviolet rays by a method of adhering the solder resist is dried and the mask. Thereafter, these were developed with a 1% sodium carbonate aqueous solution as a developer at 30 ° C. for 60 seconds in a developing machine for printed wiring boards. Subsequently, these were heat-cured in a hot-air circulating drying furnace at 150 ° C. for 60 minutes to prepare test pieces. With respect to the lines of these test pieces, the cross-sectional shape was measured with a microscope on the upper surface in contact with the mask and the substrate surface in contact with the substrate. Next, the film thickness was also measured for each test piece with a surface roughness meter. Moreover, the visual observation was performed about the shape observed about each test piece. In this determination, a cross section having a substantially square shape was indicated by “◯”, and an overhang or undercut having a large reverse trapezoid was clearly indicated by “X”. The results are shown in Table 2. The unit is μm.

  According to Table 2, Examples 1 to 5 and Comparative Examples also used a bisacylphosphine oxide photopolymerization initiator (B) and a monoacylphosphine oxide photopolymerization initiator (C) in combination. The cross-sectional shape has a small difference in dimensions between the upper surface and the base material surface, and the cross-sectional shape is almost square, so that excellent resolution is obtained.

(2) Light resistance and heat discoloration resistance The solder resist compositions of Examples 1 to 5 and Comparative Examples 1 and 5 that were good in the resolution test were 100 mm × 150 mm in size and 1.6 mm in thickness. A pattern was printed on the FR-4 copper-clad laminate by a screen printing method using a 100-mesh polyester (made by Bias) plate so that the film thickness was 40 μm. Then, these were dried at 80 ° C. for 30 minutes in a hot air circulation type drying furnace. Furthermore, these were exposed to ultraviolet rays with an integrated light quantity of 900 mJ / cm ² so as to leave a 30 mm square negative pattern using an exposure machine HMW-680GW (manufactured by Oak Manufacturing Co., Ltd.). Thereafter, 1% sodium carbonate aqueous solution is used as a developing solution at 30 ° C., and these are developed for 60 seconds with a developing machine for printed wiring boards. Subsequently, heat curing is performed at 150 ° C. for 60 minutes in a hot-air circulating drying furnace. Each test piece for a characteristic test was produced.

The obtained test piece was measured with a color difference meter CR-400 (manufactured by Konica Minolta Sensing Co., Ltd.). Further, for each test piece, using a conveyor type UV irradiator QRM-2082-E-01 (manufactured by Oak Manufacturing Co., Ltd.), metal halide lamp, cold mirror, 120 W / cm ² × 3 lamp, conveyor speed 3 m / min (wavelength UV irradiation was repeated 50 times under the condition of an integrated light quantity of about 3000 nm (3000 mJ / cm ² ). (In calculation, the integrated light amount is 150 J / cm ² ) Then, for each test piece after UV irradiation, the color difference was measured under the same conditions as the initial values, and the deterioration state was evaluated.

Next, each test piece after the light resistance test was repeatedly heated twice using a conveyor heating furnace for component mounting. For each test piece after heating, the color difference was measured under the same conditions as the initial values, and the deterioration state of each test piece was evaluated. Each test piece was also evaluated visually. Each result is shown in Table 3. The temperature of the heating furnace is shown in FIG.

In Table 3, Y represents the reflectance of the XYZ color system, and L ^* represents the lightness of the L ^* a ^* b ^* color system. ΔE * ab is obtained by taking the square of the difference between the value after the deterioration test and the initial value for each value of L * a * b * and taking the square root of the sum. a ^* indicates the red direction, -a ^* indicates the green direction, b ^* indicates the yellow direction, and -b ^* indicates the blue direction. The closer to zero, the lower the saturation. ΔE ^* ab represents a color change, and the smaller this value, the smaller the color change.

  In Examples 1 to 5, both the light resistance test and the heat test were good results with little change in the value of ΔE * ab and visual evaluation.

(3) Solder heat resistance About Examples 1-5, the rosin-type flux was apply | coated to each test piece produced similarly to (2), and it was made to flow for 10 second in a 260 degreeC solder tank. Thereafter, these were washed with propylene glycol monomethyl ether acetate and dried, and then a peel test with a cellophane adhesive tape was performed to evaluate the peeling of the coating film. In this evaluation, the case where there was no peeling was rated as “◯” and the case where there was peeling as “X”. The results are shown in Table 4.

(4) Solvent resistance For each of Examples 1 to 5, each test piece prepared in the same manner as (2) was immersed in propylene glycol monomethyl ether acetate for 30 minutes and dried, and then a peel test using a cellophane adhesive tape was performed. The film peeling was evaluated. In this evaluation, the case where there was no peeling was rated as “◯” and the case where there was peeling as “X”. The results are shown in Table 4.

(5) Pencil hardness test About Examples 1-5, the pencil of B to 9H sharpened so that the tip of a core may become flat about 45 degrees about each test piece produced like (2). Pressed at an angle, the hardness of the pencil at which the coating film did not peel off was recorded. The results are shown in Table 4.

(6) Insulation resistance test For Examples 1 to 5, each test was performed under the same conditions as in (2) except that a comb-type electrode B coupon having an IPC B-25 test pattern was used instead of the FR-4 copper-clad laminate. A piece was made. A DC 500 V bias was applied to these test pieces, and the insulation resistance values were measured. When the value was 100 GΩ or more, it was rated as “◯”, and when it was less than 100 GΩ, it was marked as “X”. The results are shown in Table 4.

  As is clear from Table 4, Examples 1 to 5 using the solder resist composition of the present invention have good heat resistance, solvent resistance, adhesion and electrical insulation required for the solder resist. I understood.

  As described above in detail, it has been found that the solder resist composition of the present invention is excellent in resolution even when titanium oxide is blended. Moreover, the solder resist formed using the solder resist composition of the present invention has little discoloration due to light and heat, and is excellent in high reflectance.

Claims (9)

  (A) carboxyl group-containing resin having no aromatic ring, (B) bisacylphosphine oxide photopolymerization initiator, (C) monoacylphosphine oxide photopolymerization initiator, (D) photopolymerizable monomer, A solder resist composition comprising (E) rutile titanium oxide and (G) an organic solvent.   The carboxyl group-containing resin (A) having no aromatic ring is (a) a carboxyl group-containing (meth) acrylic copolymer resin, and (b) a compound having an oxirane ring and an ethylenically unsaturated group in one molecule. The solder resist composition according to claim 1, wherein the solder resist composition is a copolymer resin having a carboxyl group obtained by a reaction with the solvent.   (F) The solder resist composition according to claim 1, further comprising an epoxy compound.   The solder resist composition according to claim 1, further comprising (H) a thioxanthone photopolymerization sensitizer. In a printed wiring board provided with a base material on which a cured product of a solder resist composition is formed,
The cured product is
(A) carboxyl group-containing resin having no aromatic ring, (B) bisacylphosphine oxide photopolymerization initiator, (C) monoacylphosphine oxide photopolymerization initiator, (D) photopolymerizable monomer, And (E) a printed wiring board comprising rutile titanium oxide.   The carboxyl group-containing resin (A) having no aromatic ring is (a) a carboxyl group-containing (meth) acrylic copolymer resin, and (b) a compound having an oxirane ring and an ethylenically unsaturated group in one molecule. The printed wiring board according to claim 5, wherein the printed wiring board is a copolymer resin having a carboxyl group obtained by a reaction with the resin.   The printed wiring board according to claim 5 or 6, wherein the cured product further contains (F) an epoxy compound.   The printed wiring board according to any one of claims 5 to 7, further comprising (H) a thioxanthone photopolymerization sensitizer.   The printed wiring board according to any one of claims 5 to 8, wherein the printed wiring board substrate is mounted with a light emitting diode.

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