KR101718996B1 - Solder resist composition and printed wiring board - Google Patents

Abstract

The present invention provides a solder resist composition with high reflectance and high resolution, and a printed wiring board obtained by forming a solder resist therefrom by preventing a decrease in reflectance caused by deterioration of color fading.
The solder resist composition of the present invention is a solder resist composition comprising (A) a carboxyl group-containing resin having no aromatic ring, (B) a bisacylphosphine oxide-based photopolymerization initiator, (C) a monoacylphosphine oxide- A polymerizable monomer, (E) a rutile-type titanium oxide, and (G) an organic solvent.

Description

[0001] Description [0002] SOLDER RESIST COMPOSITION AND PRINTED WIRING BOARD [0003]

The present invention relates to a solder resist composition capable of forming a solder resist having a high reflectance suitable for use as a permanent mask of a printed wiring board and a solder resist composition capable of forming a solder resist pattern using the solder resist composition on the surface of a circuit board To a wiring board.

A printed wiring board is generally formed by removing unnecessary portions of a copper foil bonded to a laminate by etching to form circuit wiring, and electronic components are disposed at predetermined locations by soldering. Solder resists are used for such printed wiring boards as protective films for circuitry when soldering electronic components, which are applied to a substrate and cured.

The solder resist prevents solder from attaching to an unnecessary portion at the time of soldering, and also prevents the circuit conductor from being directly exposed to air and deteriorated by oxygen or moisture. The solder resist also functions as a permanent protective film of the circuit board. For this reason, various properties such as adhesion, electrical insulation, solder heat resistance, solvent resistance, and chemical resistance are required.

In addition, the printed wiring board has become finer (fine), multi-layered and original board for high density realization, and the mounting method has also been changed to surface mounting technology (SMT). For this reason, demands for fine soldering, high resolution, high accuracy, and high reliability are also increasing in solder resist.

As a technique for forming a pattern of such a solder resist, a photolithography method capable of accurately forming a fine pattern has been used. In particular, an alkaline developing type photolithography method is predominant in consideration of the environment.

For example, Patent Documents 1 and 2 disclose a solder resist composition capable of being developed with an alkaline aqueous solution containing a novolak type epoxy resin with an unsaturated monocarboxylic acid and further reacting a polybasic acid anhydride with a reaction product as a base polymer .

On the other hand, there has recently been an increasing demand for mounting a light emitting diode (LED) that emits light at low power directly on a printed wiring board on which a solder resist is coated as a backlight of a liquid crystal display such as a portable terminal, a personal computer, have.

Therefore, in order to efficiently utilize the light of the LED, a printed wiring board in which the solder resist is made white so as to have a high reflectance is required.

However, since the white solder resist has a high reflectance in the composition itself, it can not sufficiently absorb light required for its curing by reflecting light at the time of patterning exposure, and the resolution is degraded. As a result, .

In a printed wiring board in which a direct LED is mounted, deterioration and coloring of the white solder resist are promoted by light and heat generated from the LED, and the reflectance is lowered.

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

It is an object of the present invention to provide a solder resist composition and a printed wiring board for forming a solder resist film of high reflectivity and high resolution capable of efficiently utilizing LED light.

It is also an object of the present invention to provide a solder resist composition and a printed wiring board capable of preventing deterioration and coloring of a solder resist due to light and heat generated from an LED.

As a result of intensive studies, the present inventors have found that, by using a resin that does not have an aromatic ring as a carboxyl group-containing resin having thermal curability that enables alkali development and uses rutile titanium oxide as a white pigment for achieving high reflectance, It is possible to suppress deterioration due to light or heat for a long period of time and to use a combination of a bisacylphosphine oxide-based photopolymerization initiator and a monoacylphosphine oxide-based photopolymerization initiator as a photopolymerization initiator in combination with a large amount of rutile- It is possible to form a pattern latent image with high resolution and 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- (E) a rutile-type titanium oxide and (G) an organic solvent, and may further contain (F) an epoxy compound or (H) thioxanthone-based photopolymerization-sensitizer.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a solder resist which has properties such as coatability, light curability, developability, solder heat resistance, adhesion, and electrical insulation required as a developer solder resist and which suppresses coloration due to deterioration of reflectance and deterioration over time A solder resist film having high reflectance and high resolution can be formed. Further, 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.

1 shows the temperature of the heating furnace used in the light resistance / heat discoloration test of the test pieces of Examples and Comparative Examples.

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

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

(Carboxyl group-containing resin having no aromatic ring)

As the carboxyl group-containing resin (A) having no aromatic ring, both a photosensitive carboxyl group-containing resin having at least one photosensitive unsaturated double bond and a carboxyl group-containing resin having no photosensitive unsaturated double bond can be used, . In particular, among the resins listed below, those having no aromatic ring (which may be either oligomer or polymer) can be preferably used. That is, the present invention provides a resin composition comprising (1) a carboxyl group-containing resin obtained by copolymerization of a compound having an unsaturated carboxylic acid and an unsaturated double bond, (2) a compound having an oxirane ring and an ethylenically unsaturated group in a molecule in a carboxyl group- (3) reacting an unsaturated monocarboxylic acid with a copolymer of a compound having an epoxy group and an unsaturated double bond in each molecule and a compound having an unsaturated double bond, and Containing resin obtained by reacting the produced secondary hydroxyl group with a saturated or unsaturated polybasic acid anhydride, (4) reacting a hydroxyl group-containing polymer with a saturated or unsaturated polybasic acid anhydride, and then adding 1 to the carboxylic acid produced by the reaction A compound having an epoxy group and an unsaturated double bond in each molecule And a photosensitive hydroxyl group and a carboxyl group-containing resin.

Among them, the carboxyl group-containing (meth) acrylic copolymer resin (a), which is the photosensitive carboxyl group-containing resin of the above (2), and the carboxyl group- A copolymer resin is preferable.

(meth) acrylic copolymer resin of the carboxyl group (a) is obtained by copolymerizing a (meth) acrylic acid ester with a compound having one unsaturated group and at least one carboxyl group in one molecule. Examples of the (meth) acrylic esters constituting the copolymer resin (a) include acrylic esters such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, caprolactone- (Meth) acrylates such as methoxyethyleneglycol (meth) acrylate, ethoxydiethyleneglycol (meth) acrylate, isooctyloxydiethyleneglycol (meth) acrylate, Glycol-modified (meth) acrylates such as phenoxy triethylene glycol (meth) acrylate, methoxy triethylene glycol (meth) acrylate and methoxypolyethylene glycol (meth) Methacrylate, and the like. These may be used alone or in combination of two or more. In the present specification, (meth) acrylate is a generic term for acrylate and methacrylate, and the same applies to other similar expressions.

Examples of the compound having one unsaturated group and at least one carboxyl group in one molecule include acrylic acid, methacrylic acid, and modified unsaturated monocarboxylic acids in which a chain between the unsaturated group and the carboxylic acid is extended, for example,? -Carboxyethyl ( 2-acryloyloxyethylhexahydrophthalic acid, an unsaturated monocarboxylic acid having an ester bond by lactone modification or the like, a modified unsaturated monocarboxylic acid having an ether bond, And further includes two or more carboxyl groups such as maleic acid in the molecule. These may be used alone or in combination of two or more.

(b) a compound having an oxirane ring and an ethylenically unsaturated group in one molecule is preferably a compound having an ethylenically unsaturated group and an oxirane ring in one molecule, and examples thereof include glycidyl (meth) acrylate, Epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylmethylaminoacrylate, and the like. Of 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) having no aromatic ring needs to have an acid value of 50 to 200 mgKOH / g. When the acid value is less than 50 mgKOH / g, it is difficult to remove the unexposed portions of the solder resist composition coating film in a weakly alkaline aqueous solution. When the acid value exceeds 200 mgKOH / g, there is a problem that the water resistance and electric characteristics of the cured coating deteriorate. The weight average molecular weight of the carboxyl group-containing resin (A) having no aromatic ring is preferably in the range of 5,000 to 100,000. If the weight-average molecular weight is less than 5,000, the dry-to-dry composition of the solder resist composition coating film tends to remarkably decrease. On the other hand, if the weight average molecular weight exceeds 100,000, development and storage stability of the solder resist composition deteriorate remarkably, which is not preferable.

(Photopolymerization initiator)

(Bisacylphosphine oxide-based photopolymerization initiator)

Examples of the bisacylphosphine oxide-based photopolymerization initiator (B) used in the present invention include bis- (2,6-dichlorobenzoyl) phenylphosphine oxide, bis- (2,6-dichlorobenzoyl) (2,6-dichlorobenzoyl) -4-propylphenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -1-naphthylphosphine oxide, bis- Dimethoxybenzoyl) phenylphosphine oxide, bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis- (2,6- dimethoxybenzoyl) (2,4,6-trimethylbenzoyl) phenylphosphine oxide, (2,5,6-trimethylbenzoyl) -2,4,4-trimethylpentylphosphine oxide, and the like. Among them, bis- (2,4,6-trimethylbenzoyl) phenylphosphine oxide (trade name: Irgacure 819, manufactured by Shiba Japan Co., Ltd.) is easily available and practical.

(Monoacyl phosphine oxide-based photopolymerization initiator)

Examples of the monoacylphosphine oxide-based photopolymerization initiator (C) used in the present invention include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6- Dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphinic acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphinic acid isopropyl ester, and the like. Of these, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (product name: DARACURE TPO, manufactured by Shiba Japan Co., Ltd.) is easily available and practical.

The solder resist composition of the present invention may also be a high-reflectance coating film in which titanium oxide is blended by using the bisacylphosphine oxide-based photopolymerization initiator (B) and the monoacylphosphine oxide-based photopolymerization initiator (C) Light can be absorbed, and a high-precision pattern can be formed. Further, by changing the blending ratio thereof, the light absorption of the coating film can be finely adjusted. That is, when the cross-sectional shape of the pattern tends to cause undercutting due to insufficient hardening of the core portion on the substrate side, the proportion of the bisacryl phosphine oxide-based photopolymerization initiator (B) is increased. When the surface condition after the development is deteriorated due to insufficient surface curability, the proportion of the monoacylphosphine oxide-based photopolymerization initiator (C) is increased. The blending ratio of the bisacylphosphine oxide-based photopolymerization initiator (B) to the monoacylphosphine oxide-based photopolymerization initiator (C) is 90:10 to 1:99, preferably 80:20 to 2:98. If the blend ratio is out of the range, the effect of the combined use is reduced and the required light can not be absorbed, so that a high-precision pattern can not be formed.

The total amount of the bisacylphosphine oxide-based photopolymerization initiator (B) and the monoacylphosphine oxide-based photopolymerization initiator (C) is preferably 1 to 100 parts by mass based on 100 parts by mass of the carboxyl group-containing resin (A) To 30 parts by mass, and more preferably 2 to 25 parts by mass. When the total amount of the bisacylphosphine oxide-based photopolymerization initiator (B) and the monoacylphosphine oxide-based photopolymerization initiator (C) is less than 1 part by mass, the photocurability is lowered and it is difficult to form a pattern after exposure and development Which is undesirable. On the other hand, when the total amount is more than 30 parts by mass, the coloring of the coating film derived from the photopolymerization initiator is increased and the unit cost is increased, which is not preferable.

(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; Mono or diacrylates of glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol and propylene glycol; Acrylamides such as N, N-dimethylacrylamide and N-methylolacrylamide; Aminoalkyl acrylates such as N, N-dimethylaminoethyl acrylate; Polyhydric alcohols such as hexanediol, trimethylol propane, pentaerythritol, dipentaerythritol, and tris-hydroxyethylisocyanurate, or polyhydric acrylates of these ethylene oxide or propylene oxide adducts; Acrylates such as phenoxy acrylate, bisphenol A diacrylate and ethylene oxide or propylene oxide adduct of phenols thereof; Acrylates of glycidyl ethers such as glycerin diglycidyl ether and trimethylol propane triglycidyl ether; Melamine acrylate; And / or methacrylates corresponding to the above-mentioned 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 based on 100 parts by mass of the carboxyl group-containing resin (A) having no aromatic ring. When the blending amount exceeds 100 parts by mass, the physical properties of the cured coating film as the solder resist are lowered, which is not preferable. On the other hand, if the blending amount is less than 10 parts by mass, there is no sufficient photocurability and a high-precision pattern can not be obtained.

(Rutile type titanium oxide)

In the present invention, rutile titanium oxide (E) is used as a white pigment. Typical titanium oxide includes anatase type and rutile type. Since the anatase-type titanium oxide has photocatalytic activity, the resin in the solder resist composition may discolor in some cases. On the other hand, the rutile-type titanium oxide has absorption in the vicinity of the boundary between the ultraviolet ray region and the visible light region, compared with the anatase type titanium oxide, and is insufficient in terms of the whiteness degree and reflectivity of the entire visible light region. However, Can be obtained.

As the rutile-type titanium oxide (E), known ones can be used. Specific examples of the composition include Tiepech R-820, Tiefeque R-830, Tiefeque R-930, Tiefeque R-550, Tiefeque R-630, Tiefeque R-680, Tieferc CR-90, Tieferc CR-93, Tiefer CR-80, Tieferc CR-50, Tieferc CR-80, Tieferc CR-80, Tieferc CR- (Manufactured by Ishihara Sangyo Kabushiki Kaisha, Ltd.), which is manufactured by Nippon Oil & Fats Co., Ltd., Taipure R-101, Taipure R-102, Taipure R-103, Taipure R-104, Taipure R-105, Taipure R-108, (TITON) R-25, TITON R-21, TITON R-32, TITAN R-901, Titan PURE R-902, TITON R-7E, TITON R-61N, TITON R-62N, TITON R-42, TITON R-45M, TITON R-44, TITON R- GTR-300, Teton D-918, Teton-TCR 29, TCR-Teton 52, Teton FTR-700 (used up or wrong sikki Kagaku Kogyo Ltd.) and the like can be used.

The blending amount of the rutile titanium oxide (E) is preferably 50 to 450 parts by mass, more preferably 60 to 350 parts by mass based on 100 parts by mass of the carboxyl group-containing resin (A) having no aromatic ring. When the blending amount exceeds 450 parts by mass, the photocurability is lowered and the depth of curing 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 solder resist with high reflectance can not be obtained.

(Epoxy compound)

Subsequently, examples of the epoxy compound (F) include bisphenol S type epoxy resin, diglycidyl phthalate resin, triglycidyl isocyanurate (for example, TEPIC (trade name) manufactured by Nissan Chemical Industries, H (a? -Form having a structure in which three epoxy groups are bonded to the S-triazine ring skeletal surface in the same direction), a tectic (? -Form and an epoxy group having one epoxy group different from the other two epoxy groups A mixture of an α-isomer having a structure bonded to the epoxy resin in the direction of the epoxy resin, etc.), epoxy resin which is sparingly soluble in a diluent such as biquilene-type epoxy resin, biphenyl-type epoxy resin and tetraglycidylsilane- Bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type resin, brominated bisphenol A type epoxy resin, phenol novolak type or cresol novolak type epoxy resin, Epoxy resin, novolak type epoxy resin of bisphenol A, chelate type epoxy resin, glyoxyl type epoxy resin, amino group containing epoxy resin, rubber modified epoxy resin, dicyclopentadiene phenolic epoxy resin, silicone modified epoxy resin, And an epoxy resin soluble in a diluent such as a lactone-modified epoxy resin. These epoxy resins may be used alone or in combination of two or more.

The amount of such an epoxy compound (F) is preferably 5 to 70 parts by mass, more preferably 5 to 60 parts by mass based on 100 parts by mass of the carboxyl group-containing resin (A) having no aromatic ring. When the compounding amount of the epoxy compound (F) is more than 70 parts by mass, the solubility of the unexposed portion in the developer is lowered, and development residue tends to be generated. 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, so that it becomes difficult to sufficiently obtain the electrical characteristics of the cured coating film, the soldering heat resistance, There is a tendency.

The carboxyl group of the carboxyl group-containing resin (A) having no aromatic ring and the epoxy group of the epoxy compound (F) react by ring-opening polymerization. In addition, when an epoxy resin which is easy to dissolve is used as the other material in the organic solvent (G) or the solder resist composition, the cross-linking between the carboxyl group and the epoxy group tends to proceed by the heat at the time of drying. Therefore, when it is desired to suppress the crosslinking reaction and to prolong the drying time, it is preferable to use an insoluble epoxy resin alone or in combination with an epoxy resin which is easy to dissolve.

(Organic solvent)

The organic solvent (G) used in the present invention is used to make a solder resist composition easy to apply, to apply it to a substrate or the like, and then to dry to form 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, propylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropreneglycol monoethyl ether, triethylene glycol monoethyl ether And the like; Esters such as ethyl acetate, butyl acetate, cellosolve acetate, diethylene glycol monoethyl ether acetate and esters of the glycol ethers; Alcohols such as ethanol, propanol, ethylene glycol and propylene glycol; Aliphatic hydrocarbons such as octane and decane; Petroleum ether such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha.

The organic solvent (G) may be used alone or as a mixture of two or more kinds. The blending amount of the organic solvent (G) is preferably 20 to 300 parts by mass based on 100 parts by mass of the carboxyl group-containing resin (A) having no aromatic ring.

(Thioxanthene photopolymerization sensitizer)

In the present invention, it is preferable to blend a thiosecondant-based photo polymerization sensitizer (H) for the purpose of improving the sensitivity to light upon exposure. Since the effect of the thiosecanthone-based photopolymerization-sensitizer (H) is very high in the composition in which the bisacylphosphine oxide-based photopolymerization initiator (B) and the monoacylphosphine oxide-based photopolymerization initiator (C) to be. Examples of the thioxanthene photo-polymerization sensitizer (H) include thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2 , 4-diethyl thioxanthone, and 2,4-diisopropyl thioxanthone.

The blending amount of the thioxantanone photopolymerization sensitizer (H) is preferably 0.05 to 2 parts by mass, more preferably 0.1 to 1 part by mass based on 100 parts by mass of the carboxyl group-containing resin (A) having no aromatic ring . If the blending amount is less than 0.05 part by mass, the effect of improving the sensitivity is small, and if it exceeds 2 parts by mass, the coloring of the coating film derived from the thioxanthone becomes large.

(Other components)

(stabilizator)

In addition, in the solder resist composition of the present invention, photo deterioration can be reduced by containing a hindered amine light stabilizer.

Examples of hindered amine light stabilizers include Tinuvin 622LD, Tinuvin 144; CHIMASSORB 944LD, Chima sorb 119FL (all manufactured by Shiba Japan K.K.); MARK LA-57, LA-62, LA-67, LA-63 and LA-68 (all manufactured by Adeka Kabushiki Kaisha); LS-770, LS-765, LS-292, LS-2626, LS-1114 and LS-744 (all manufactured by Sankyo Life Tech Co., Ltd.).

The light stabilizer is preferably added in an amount of 0.1 to 10 parts by mass based on 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, dispersibility and sedimentation of titanium oxide can be improved by containing a dispersant. Examples of the dispersing agent include antistatic agents such as ANTI-TERRA-U, ANTI-TERA-U100, ANTI-TERA-204, ANTI- -103, Dispersive-106, Dispersive-108, Dispersive-109, Dispersive-110, Dispersive-111, Dispersive-112, Dispersive-116, Dispersive- -142, Disperby-145, Disperby-161, Disperby-162, Disperby-163, Disperobic-164, Disperobic-166, Disperobic-167, Disperobic- -171, Dispersive-174, Dispersive-180, Dispersive-182, Dispersive-183, Dispersive-185, Dispersive-184, Dispersive-2000, Dispersive- -2020, DISPERBIC-2025, DISPERBIC-2050, DISPERBIC-2070, DISPERBIC-2096, DISPERBIC-2150, BYK-P104, BIG-P104S, BIG-P105, BIG- , Big-220S (manufactured by Big Chem Co., Ltd.), Disalon 2150, Disalon 1210, Disalon KS-860, Disparon DA-703-50 (manufactured by SUMOTO KASEI KABUSHIKI KAISHA) was used as a solvent, and the mixture was stirred at room temperature for 1 hour. ), Floren G-450, Floren G-600, Floren G-820, Floren G-700, Floren DOPA-44 and Floren DOPA-17 (manufactured by Kyoeisha Chemical Co., Ltd.) .

The content of the dispersant is preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass based on 100 parts by mass of the rutile titanium oxide (E) in order to effectively achieve the above object.

(Other ingredients added)

If necessary, a curing accelerator, a thermal polymerization inhibitor, a thickener, a defoaming agent, a leveling agent, a coupling agent, and a flame-retardant aid may be used in the solder resist composition of the present invention.

(Manufacturing method)

Hereinafter, the production of a printed wiring board will be described as an example of using the solder resist composition.

First, the solder resist composition of the present invention is diluted as necessary and adjusted to a viscosity suitable for the application method.

Then, the viscosity-adjusted composition is applied to a printed wiring board by a screen printing method, a curtain coating method, a spray coating method, a roll coating method or the like. Further, an organic solvent contained in the composition applied at a temperature of, for example, 70 to 90 ° C is volatilized and dried to form a tack-free coating film.

Thereafter, the coating film is selectively exposed through an active energy ray through a photomask, and the unexposed portion is developed with an aqueous alkali solution to form a resist pattern. Further, the resist pattern is thermally cured at 100 占 폚 to 200 占 폚 to form a solder resist pattern.

As the irradiation light source for exposure, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a xenon lamp or a metal halide lamp can be used. In addition to this, a laser beam or the like can also be used as an active ray.

As the aqueous alkali solution, 0.5 to 5 mass% of an aqueous solution of sodium carbonate is generally used. It is also possible to use another aqueous alkali solution. Examples of other alkali aqueous solutions include aqueous alkaline solutions such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium phosphate, sodium silicate, ammonia, and amines.

Further, after the solder resist pattern is formed, the LED is mounted to manufacture the printed wiring board according to the present invention. The printed wiring board according to the present invention is manufactured using a solder resist containing titanium oxide having a high reflectance according to the present invention and has a pattern with high reflectance and high accuracy.

[Example]

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited thereto.

(A) Synthesis of carboxyl group-containing resin having no aromatic ring

Synthesis Example 1

A 2-liter separable flask equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel and a nitrogen inlet tube was charged with 900 g of diethylene glycol dimethyl ether as a solvent and 10 g of t-butylperoxy 2-ethylhexanoate 21.4 g of commercial product name: perbutyl O) was added and heated to 90 占 폚. After heating, 309.9 g of methacrylic acid, 116.4 g of methyl methacrylate, and 109.8 g of lactone-modified 2-hydroxyethyl methacrylate (trade name: Fraxel FM1, manufactured by Daicel Chemical Industries, Ltd.) Was added dropwise over 3 hours together with 21.4 g of bis (4-t-butylcyclohexyl) peroxydicarbonate (trade name; manufactured by Nippon Kayaku Co., Ltd .; peryl TCP). This was aged for 6 hours to obtain a carboxyl group-containing copolymer resin. These reactions were carried out in a nitrogen atmosphere.

Subsequently, 363.9 g of 3,4-epoxycyclohexylmethyl acrylate (trade name; manufactured by Daicel Chemical Industries, Ltd., product name: SICHROMER A200), 3.6 g of dimethylbenzylamine as a ring opening catalyst, 1.80 g of quinone monomethyl ether was added and heated to 100 占 폚 and stirred to effect ring-opening addition reaction of epoxy. After 16 hours, a solution containing 53.8% by mass (nonvolatile content) of a carboxyl group-containing resin having no aromatic ring 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

Diethylene glycol monoethyl ether acetate as a solvent and azobisisobutyronitrile as a catalyst were placed in a flask equipped with a stirrer, a thermometer, a stirrer, a dropping funnel and a reflux condenser, and the mixture was heated at 80 DEG C under a nitrogen atmosphere. Methacrylic acid and methyl methacrylate Acrylate in a molar ratio of 0.40: 0.60 was added dropwise over about 2 hours. After stirring for 1 hour, the temperature was raised to 115 캜, and the solution was deactivated to obtain a resin solution.

After the resin solution was cooled, tetrabutylammonium bromide was used as a catalyst, and butylglycidyl ether was added and reacted with the equivalent amount of the carboxyl group of the resin obtained at a molar ratio of 0.40 at 95 to 105 ° C for 30 hours And cooled.

Further, the OH groups of the resin obtained above were subjected to an addition reaction at a molar ratio of 0.26 of tetrahydrophthalic anhydride at 95 to 105 캜 for 8 hours. This was cooled and taken out to obtain a solution containing 50 mass% (nonvolatile content) of a carboxyl group-containing resin having an acid value of 78.1 mgKOH / g and a weight average molecular weight of 35,000 without an aromatic ring. Hereinafter, this reaction solution is referred to as A-2 varnish.

(B) Synthesis of carboxyl group-containing resin having aromatic ring

Comparative Synthesis Example 1

210 g of a cresol novolac epoxy resin (Epiclon N-680, manufactured by DIC Co., Ltd., epoxy equivalent = 210) and 96.4 g of carbitol acetate as a solvent were added to a flask equipped with a thermometer, a stirrer, a dropping funnel and a reflux condenser And dissolved by heating. Then, 0.1 g of hydroquinone as a polymerization inhibitor and 2.0 g of triphenylphosphine as a reaction catalyst were added thereto. The mixture was heated to 95 to 105 DEG C, and 72 g of acrylic acid was gradually added dropwise and reacted for about 16 hours until the acid value became 3.0 mgKOH / g or less. After the reaction product was cooled to 80 to 90 ° C, 76.1 g of tetrahydrophthalic anhydride was added and the reaction was allowed to proceed for about 6 hours until the absorption peak of the acid anhydride (1780 cm ^-1 ) was eliminated by infrared absorption analysis . To this reaction solution, 96.4 g of aromatic solvent Solp # 150 manufactured by Idemitsu Kosan Co., Ltd. was added, diluted, and then removed. The thus obtained photosensitive polymer solution containing carboxyl groups had a non-volatile content of 65% by weight and an acid value of solid matter of 78 mgKOH / g. Hereinafter, this reaction solution is referred to as B-1 varnish.

Blends of Examples 1 to 5 and Comparative Examples 1 to 5:

Each component was mixed and stirred according to Table 1, and dispersed with a three-roll mill to prepare a solder resist composition. Numbers in the tables indicate mass parts.

Photopolymerization initiator A1: Bis- (2,4,6-trimethylbenzoyl) phenylphosphine oxide, Irgacure 819 (manufactured by Shiba Japan Co.)

Photopolymerization initiator A2: 2,4,6-trimethylbenzoyldiphenylphosphine oxide, DAROCURE TPO (manufactured by Shiba Japan)

Photopolymerization initiator B1: Irgacure 907 (Shiba Japan)

Photopolymerizable monomer: dipentaerythritol hexaacrylate

Titanium oxide A: Rutile titanium oxide CR-95 (manufactured by Ishihara Sangyo Co.)

Titanium oxide B: Anatase type titanium oxide A-220 (manufactured by Ishihara Sangyo Co.)

Epoxy compound: Tepic-H (manufactured by Nissan Chemical Industries, Ltd.)

Thermal curing accelerator: Dicyandiamide

Sensitizer: 2,4-diethylthioxanthone, Kayacure DETX-S (manufactured by Nippon Kayaku Co., Ltd.)

Solvent: Carbitol acetate

Defoaming agent (silicone oil): KS-66 (manufactured by Shinetsu Chemical Co., Ltd.)

In order to investigate various properties of the solder resist formed using each solder resist composition, the following tests and evaluations were conducted.

(1) Resolution (sectional shape)

Each solder resist composition was printed on a solid (substrate entire surface) using a 100 mesh polyester (bias production) plate by a screen printing method with respect to an FR-4 copper laminate having a size of 100 mm x 150 mm and a thickness of 1.6 mm Respectively. This was dried in a hot-air circulating drying furnace at 80 DEG C for 10 minutes. Further, the solder resist composition was superimposed and printed on each of the dried coating films in the same manner and dried in a hot air circulating drying furnace at 80 캜 for 20 minutes. In Examples 1, 2, and 5, and Comparative Examples 1 to 3, a mask pattern having a negative line of 250 mu m was used by using an exposure machine HMW-680GW (manufactured by Oak Seisakusho Co., Ltd.) 450 mJ / cm 2 for 3 and 5, and Examples 3 and 4 and Comparative Example 4 were exposed to ultraviolet rays by a method of closely contacting the dried solder resist with a mask at an integrated light quantity of 900 mJ / cm 2. Thereafter, a 1% aqueous solution of sodium carbonate at 30 DEG C was used as a developer, and these were developed for 60 seconds by a developing device for a printed wiring board. Then, the test pieces were thermally cured by a hot-air circulation type drying furnace at 150 DEG C for 60 minutes to prepare test pieces. The cross-sectional shape of the test specimens was measured with a microscope, and the upper surface in contact with the mask and the substrate surface in contact with the substrate were measured. Subsequently, the film thickness of each test piece was also measured with a surface roughness meter. In addition, the shape of each of the test pieces was visually observed. In this judgment, the shape of the cross section was substantially quadrilateral, the case where the protrusion or undercut was large, and the shape which was clearly inverted trapezoid was rated as x. The results are shown in Table 2. The unit is ㎛.

According to Table 2, the use of the bisacylphosphine oxide-based photopolymerization initiator (B) in combination with the monoacylphosphine oxide-based photopolymerization initiator (C) in Examples 1 to 5 and Comparative Example is also effective in that the cross- And the cross-sectional shape was almost quadrangular, and excellent resolution was obtained.

(2) Light fastness / heat discoloration resistance

For the solder resist compositions of Examples 1 to 5 and Comparative Examples 1 and 5, which were good in the resolution test, FR-4 copper-clad laminate having a size of 100 mm x 150 mm and thickness of 1.6 mm was screen- (Total surface of the substrate) by using a plate of 100 mesh polyester (manufactured by Bias) so as to have a thickness of 1 mm. Further, they were dried in a hot-air circulating drying furnace at 80 DEG C for 30 minutes. They were exposed to ultraviolet rays at an integrated light quantity of 900 mJ / cm 2 so as to leave a negative pattern of 30 mm on each side by using an exposure machine HMW-680GW for a printed wiring board (manufactured by Oak Seisakusho Co., Ltd.). Thereafter, 1% aqueous solution of sodium carbonate was applied at 30 DEG C as a developing solution for 60 seconds with a developing device for a printed wiring board, followed by thermal curing at 150 DEG C for 60 minutes by a hot-air circulation type drying furnace to prepare test pieces for characteristics testing.

The obtained test piece was measured with a color colorimeter CR-400 (manufactured by Konica Minolta Sensing Co., Ltd.). Using a conveyor type UV irradiator QRM-2082-E-01 (manufactured by Oak Seisakusho Co., Ltd.), a metal halide lamp, a cold mirror, a 120W / m / min (cumulative light quantity of about 3000 mJ / cm < 2 > in the wavelength region of 350 nm) was repeated 50 times to irradiate UV (calculated to have an integrated light quantity of 150 J / cm2). For each test piece after UV irradiation, the color difference was measured under the same condition as the initial value, and the deterioration state was evaluated.

Subsequently, each test piece after the light resistance test was repeatedly heated twice using a conveyor type 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. Also, each of the test pieces was evaluated visually. The results are 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. DELTA E * ab is obtained by taking the square of the difference between the value after the deterioration test and the initial value with respect to each value of L * a * b *, and obtaining the square root of the sum of the values. a * indicates a red direction, -a * indicates a green direction, b * indicates a yellow direction, and -b * indicates a blue direction. DELTA E * ab indicates a change in color, and the smaller the value, the smaller the change in color.

In Examples 1 to 5, even after the light resistance test, the discoloration of the value of DELTA E * ab and the visual evaluation was small even after the heating test, which was a good result.

(3) Solder heat resistance

For each of the test pieces prepared in the same manner as in (2) of Examples 1 to 5, a rosin-based flux was applied and flowed in a solder bath at 260 캜 for 10 seconds. Thereafter, these were washed with propylene glycol monomethyl ether acetate, dried, and subjected to a peeling test using a cellophane adhesive tape to evaluate peeling of the coating film. In this evaluation, " No peeling " The results are shown in Table 4.

(4) Solvent resistance

With respect to each of Examples 1 to 5, the test pieces prepared in the same manner as in (2) were immersed in propylene glycol monomethyl ether acetate for 30 minutes, dried, and subjected to a peel test with a cellophane adhesive tape. Respectively. In this evaluation, " No peeling " The results are shown in Table 4.

(5) Pencil hardness test

For each of the test pieces prepared in the same manner as in (1) to (5), a pencil of B to 9H, which had been ground so that the end of the core was flattened, was pressed at an angle of about 45 degrees to cause peeling of the coating film The pencil hardness was recorded. The results are shown in Table 4.

(6) Insulation resistance test

Each test piece was produced under the same conditions as in (2) except that the interdigital electrode B coupon of the IPC B-25 test pattern was used in place of the FR-4 copper-clad laminate in Examples 1 to 5. A bias of DC 500 V was applied to these test pieces, and the insulation resistance value was measured. When the value was 100 G? Or more, it was rated?, And when it was less than 100 G? The results are shown in Table 4.

As is apparent from Table 4, in Examples 1 to 5 using the solder resist composition of the present invention, it was found that the solder resist had good heat resistance, solvent resistance, adhesion, and electrical insulation required for the solder resist.

As described above, it was found that the solder resist composition of the present invention is excellent in the resolution even when titanium oxide is blended. In addition, the solder resist formed using the solder resist composition of the present invention was less discolored due to light or heat, and was excellent in high reflectance.

Claims (9)

(A) a carboxyl group-containing resin having no aromatic ring, (B) a bisacylphosphine oxide-based photopolymerization initiator, (C) a monoacylphosphine oxide-based photopolymerization initiator, (D) Type titanium oxide, (G) an organic solvent, and (H) a thioxanthone-based photo-polymerization sensitizer. The resin composition according to claim 1, wherein the carboxyl group-containing resin (A) having no aromatic ring is selected from the group consisting of (a) a carboxyl group-containing (meth) acrylic copolymer resin, and (b) a compound having an oxirane ring and an ethylenically unsaturated group Wherein the solder resist composition is a copolymer resin having a carboxyl group obtained by the following method. The solder resist composition according to claim 1, further comprising (F) an epoxy compound. A printed wiring board comprising a substrate on which a cured product of a solder resist composition is formed,
(A) a carboxyl group-containing resin having no aromatic ring, (B) a bisacylphosphine oxide-based photopolymerization initiator, (C) a monoacylphosphine oxide-based photopolymerization initiator, (D) Type titanium oxide and (H) thioxanthone-based photo-polymerization sensitizer. The resin composition according to claim 4, wherein the carboxyl-containing resin (A) having no aromatic ring is selected from the group consisting of (a) a carboxyl group-containing (meth) acrylic copolymer resin, and (b) a compound having an oxirane ring and an ethylenically unsaturated group Wherein the resin is a copolymer resin having a carboxyl group. The printed wiring board according to claim 4, wherein the cured product further comprises (F) an epoxy compound. The printed wiring board according to claim 4, wherein the printed wiring board base material is provided with a light emitting diode. delete delete

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