KR100188181B1 - Photosensitive solder resist composition - Google Patents

Abstract

The present invention relates to a solder resist composition used to form a solder resist by a photo-development method, and more particularly, by containing silica coated with a silane coupling agent having a cyclic aliphatic epoxy group in a molecule represented by the following formula (1) It relates to a photosensitive solder resist composition in which the corrosion resistance of the resist is improved.

Where R is or And n is an integer of 1-6.

Description

Photoresist solder resist composition with improved corrosion resistance

The present invention relates to a solder resist composition used to form a solder resist by a photo-development method, and more particularly, by containing silica coated with a silane coupling agent having a cyclic aliphatic epoxy group in a molecule represented by the following formula (1) It relates to a photosensitive solder resist composition in which the corrosion resistance of the resist is improved.

[Formula 1]

Where R is or And n is an integer of 1-6.

Solder resists are used for the purpose of preventing the formation of solder bridges during soldering, protecting the conductive portions from corrosion, and maintaining the electrical insulation of the conductive portions during use, in response to the tendency of high-density wiring and lead spacing as the electronic components become smaller. . Unlike etch resists, solder resists used under various conditions should have the following characteristics:

(1) Preservation of adhesive force at the time of soldering (about 240 ~ 280 ℃)

(2) permanent preservation of adhesion

(3) Resistance to solvents and chemicals (chemical resistance)

(4) preservation of electrical insulation in high humidity conditions

(5) Corrosion resistance at high humidity and high temperature conditions

In order to satisfy these conditions, formation of soldering resist by screen printing of a thermosetting ink or photocurable ink has generally been put to practical use.

However, with the miniaturization and high density of printed circuits, the demand for solder resists having a wide coating thickness and high precision has been increasing, and in order to meet these demands, photo methods using photosensitive resins are mainly used. It is becoming. The overall process is to apply a solder resist ink containing a photosensitive resin to a printed circuit board on which a conductor circuit is formed, and temporarily dry by heat (usually 5 to 40 minutes at 60 to 120 ° C, preferably 10 to 25 at 70 to 90 ° C. ), And then covered with a mask having a solder resist pattern and exposed to ultraviolet light (200-600 mj / cm 2, preferably 300-500 mj / cm 2) to cure the unmasked portion, and the uncured portion of the alkaline developer (Na). ₂ CO ₃ aqueous solution) to remove and post-curing (complete curing of the unreacted photosensitive resin by heat curing or ultraviolet rays at 150 ℃ for 30-90 minutes) to complete the solder resist pattern.

This photography technique enables solder resist patterns with a wide range of coating thicknesses and high precision.

Since the use of organic solvents such as 1,1,1-trichloroethane as a developer involves problems associated with contamination of the working environment and wastewater treatment, the developer mainly used is limited to an alkaline aqueous solution, and thus resist composition (ink) A carboxyl group-modified epoxy acrylate is mainly selected and used as a photosensitive resin which comprises ink) (JP-A-62-204252, 62-204253 and 62-205112). However, resists formed from solder resist inks composed of carboxyl group-modified epoxy acrylates do not have satisfactory corrosion resistance under various conditions of high temperature and high humidity.

Accordingly, the present inventors have made extensive studies to improve the corrosion resistance of resists formed from solder resist inks composed of carboxyl group-modified epoxy acrylates, and as a result, the oil absorption is high and the viscosity, thixotropy and coating properties It has been found that the above object can be achieved when silica is coated as a part of an inorganic filler and coated with a silane coupling agent having a cyclic aliphatic epoxy group in its molecule to modify the surface thereof. This invention was completed.

Accordingly, an object of the present invention is to provide a photosensitive solder resist composition capable of improving the corrosion resistance of a resist formed of a solder resist composition composed of a carboxyl group-modified epoxy acrylate.

The above object can be attained by a photosensitive solder resist composition containing silica coated with a silane coupling agent having a cyclic aliphatic epoxy group in a molecule represented by the formula (1).

Hereinafter, each component which comprises the photosensitive soldering resist composition which concerns on this invention is demonstrated more concretely.

(A) Epoxy acrylate obtained by reaction of a compound having two or more epoxy groups in a molecule and acrylic acid, or epoxy acrylate obtained by reaction of the remaining hydroxyl group and acid anhydride of the epoxy acrylate thus obtained (hereinafter 20 to 60% by weight, wherein the average acid value is 40 to 120 and the average molecular weight is 3,500 to 12,000;

(B) 2 to 25% by weight monomer having two or more polymerizable double bonds in the molecule;

(C) 7 to 35% by weight of a thermosetting agent having at least one epoxy group in the molecule;

(D) 0.05 to 20% by weight of an amine thermal curing agent having active hydrogen in the molecule;

(E) 10-40% by weight of at least one filler; And

(F) 1-20% by weight of photopolymerization catalyst comprising at least one photoinitiator and a photosensitizer.

In order to improve the corrosion resistance of a resist, the resist composition of this invention is coated with the silane coupling agent which has a cyclic aliphatic epoxy group in the molecule | numerator represented by Formula 1 as an inorganic filler (E component) in the resist composition of the said composition. It is characterized by using the prepared silica.

Inorganic fillers (E) are fillers used for the purpose of improving the durability of cured resists, relieving shrinkage generated during curing, and increasing adhesion to substrates. Talc can be used mainly. In order to improve the viscosity, thixotropy, and coating property of a resist composition, silica with high oil absorption amount was mix | blended and used here. However, amorphous silica cannot impart desired durability and cause deterioration of physical properties such as heat resistance, and its amount of use is only 1 to 2% by weight based on the total weight of the composition. Thus, the present inventors have been able to solve the above problems of silica by coating the silane coupling agent on the silica to increase the miscibility with the resin to increase the curing density, and furthermore, when coating the specific silane coupling agent, the high resistivity It has been found that by providing electrical properties such as and low dielectric constant, the corrosion resistance of the resist can be significantly improved. In the present invention, since the silica coated with a specific silane coupling agent does not have the problem of the amorphous silica described above, it can be used in the range of 10 to 40% by weight based on the total weight of the composition, and the conventional inorganic filler talc or Amorphous silica can be used together.

Hereinafter, the other general component which comprises the composition of this invention is demonstrated.

(A) Carboxyl Modified Epoxyacrylate:

The carboxyl group-modified epoxy acrylate is obtained by the reaction of an epoxy acrylate obtained by addition reaction of acrylic acid to an epoxy group of a compound having two or more epoxy groups in a molecule, or the remaining hydroxyl group and acid anhydride of the epoxy acrylate thus obtained. As epoxy acrylate, it is preferable that acid value exists in the range of 40-120, and molecular weight exists in the range of 3,500-12,000. If the average acid value is less than 40, the resist composition is less developable in an alkaline developer, while if the average acid value is greater than 120, the cured resist film cannot maintain excellent insulation at high humidity. Moreover, when the average molecular weight is larger than 12,000, it has high viscosity, and therefore developability in alkaline developing solution is reduced and miscibility with other monomers and oligomers is reduced.

Examples of epoxy resins having two or more epoxy groups in the molecule include bisphenol A epichlorohydrin resins, novolac epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, heterocyclic epoxy resins and glycidyl ethers. Epoxy resins.

In the carboxyl group-modified epoxy acrylate, not all epoxy groups or hydroxyl groups have a carboxyl group, and some epoxy groups may remain without adding a carboxyl group. When all the epoxy groups are added to the carboxyl group, the epoxy resin which is not modified by the carboxyl group can be used together.

In the composition of the present invention, the carboxyl group-modified epoxy acrylate is used in the range of 20 to 60% by weight based on the total weight of the composition. When the amount of use thereof is less than 20% by weight, the resolution is inferior and the resist which is inferior in adhesion is formed. On the other hand, when it exceeds 60% by weight, the electrical insulation in high humidity conditions is reduced.

(B) Monomers having two or more polymerizable double bonds in the molecule:

In the soldering resist composition, in order to provide developability with respect to alkaline developing solution, the linear polymer which mainly has a carboxyl group is used as photosensitive resin, and in this invention, carboxyl group-modified epoxy acrylate is also used as photosensitive resin. However, since such a linear polymer having a carboxyl group cannot form a three-dimensional network structure, the cured resist film has a problem of poor solvent resistance. In addition, certain reactive diluents which can dissolve linear polymers having this carboxyl group in the form of compatible solvents must be used, and these particular diluents tend to reduce the electrical insulation of the composition.

This problem can be solved by using a monomer having a double bond in the molecule. That is, by using a monomer having a radically polymerizable double bond, crosslinking of the double bond can be induced by ultraviolet rays, and a three-dimensional network structure can be constructed by such crosslinking.

The monomer that can be used in the present invention is not particularly limited, and specific examples thereof include two or more polymerizable double bonds in a molecule, and include ethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, Glycerine tri (meth) acrylate, trimethylol propane tri (meth) acrylate, trimethylol ethanealkylene oxide tri (meth) acrylate, bisphenol A alkylene oxide di (meth) acrylate, dihydroxybenzenealkylene oxide (Meth) acrylate etc. can be mentioned.

(C) a thermosetting agent having at least one epoxy group in the molecule and (D) an amine-based thermosetting agent having active hydrogen in the molecule:

For the same reason, in order to increase the curing density of the ultraviolet cured resist film, an epoxy resin and an amine compound, which are thermally reactive curing agents, can be mixed.

The epoxy resin that can be used in the present invention is not particularly limited, and specific examples thereof include a thermosetting agent having one or more epoxy groups in a molecule, such as dicyclopentadiene dioxide, vinylcyclohexa-3-ene dioxide, and diglycidyl phthalate. , Diglycidyl aniline, and the like. Moreover, it does not specifically limit as an amine thermosetting agent which has active hydrogen in a molecule | numerator, As a specific example, m -xylenediamine, N-aminoethyl piperazine, m -phenylenediamine, diaminophenylene methane, polyamino Imidazoline, dietetoluenediamine, and the like.

These epoxy-based thermosetting agents and amine-based thermosetting agent can cure the carboxyl group-modified epoxy acrylate by thermal reaction, thereby increasing the curing density of the resist film cured by ultraviolet light to improve physical properties such as heat resistance, hardness, wear resistance You can.

(E) at least one filler

In order to improve the corrosion resistance of a resist, the soldering resist composition which concerns on this invention uses the silica coated with the silane coupling agent which has a cyclic aliphatic epoxy group in the molecule | numerator represented by General formula (1) as an inorganic filler. Specific examples include (3,4-epoxycyclohexyl) methyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3- (3,4-epoxycyclohexyl) propyltrimethoxy Silane, 2- (3,4-epoxycyclopentyl) ethyltrimethoxysilane, and the like.

In addition, it is possible to use a talc that has been commonly used to increase the curing density of the resist film to improve the properties such as heat resistance, amorphous silica that has been used to improve the properties such as flow prevention, thixotropy, printability of the composition You can also use together.

(F) a photopolymerization catalyst comprising at least one photoinitiator and a photosensitizer:

The photopolymerization catalyst is a compound that generates radicals when exposed to active light such as ultraviolet rays or visible light, and specific examples thereof include 2-methylanthraquinone, benzoethyl ether, benzophenone, benzyldimethyl ketal, and 4-isopropyl-2-. Hydroxy-2-methylpropiophenone, 2-hydroxy-methylpropiophenone, and the like. These photopolymerization catalysts are used alone or as a mixture of two or more thereof.

In addition to these components, a thermal polymerization inhibitor, an antifoaming agent, a leveling agent, a diluent, a pigment, and the like can be blended.

The solder resist composition should have a sufficiently fluid viscosity at room temperature, but it is preferable to have a 180 ± 20 poise at 25 ° C. with an EHD viscometer in consideration of workability.

Hereinafter, the structure and effect of the soldering resist composition of this invention are given more concretely about an Example and a test example.

(Examples and Comparative Examples)

(A) Epoxy acrylate: Modified epoxy epoxy block resin (SP-3500)

(B) Monomer:

(C) Epoxy watch thermosetting agent:

Triglycidyl isocyanurate (epoxy equivalent: 105 or more, molecular weight: 297.27)

②4,4'-diglycidyl-2,2 ', 3,3'-tetramethylbiphenol (4,4'-Diglycidyl -2,2', 3,3'-tetramethylbiphenol) (epoxy equivalent: 180 ~ 192)

(D) amine based thermosetting agent:

① Dicyandiamide (molecular weight: 84.08)

②Hydroxymethyl melamine

(E) Filler:

E-1: B-30 (Tokyo Chemical Co., Ltd.)

Barium sulfate

Oil absorption: 14 ~ 23 (cm 3 / 100g)

Particle Size: 99% below 5㎛, 70% above 2㎛

High price, very high whiteness, highly purified is insoluble in water

Insoluble in alkali, soluble in hot sulfuric acid

E-2: Crystalite 5x. (Kaya Kaolin Industry Co., Ltd.)

High purity crystalline quartz filler, SiO ₂ 99.8% or more

Average particle size: 1.5㎛

Insulation, removal of alumina, high thermal conductivity (acid resistance, chemical resistance, abrasion resistance, etc.), increased insulation resistance and hardenability

E-3: Spectra K. (Koya Kaolin Industry Co., Ltd.)

Microparticles of Mg ₂ [Si ₈ O ₂₀ ] (OH) ₄ , white talc

SiO ₂ 62.61%, MgO 31.8%, Al ₂ O ₃ 0.2%

Average particle size: 3.2㎛

E-4: Kaolin (土屋 Kaolin Industry Co., Ltd.)

SiO ₂ 78.1%, Al ₂ O ₃ 17%, Fe ₂ O ₃ 0.15%, CaO 0.1%, MgO 0.1%

Whiteness 85% or more, moisture 1.5%, specific gravity 18 ~ 24g / 100cc

Average particle size: 5㎛ or less

E-5: IMSIL A-108 (Tatsumori Ltd.)

amorphous soft silica surface-treated with γ-glycidoxypropyltrimethoxysilane

E-6: LP (Japan Silica Industry Co., Ltd.)

93% or more of SiO ₂ (fine particles called white carbon)

pH 5.5 ~ 6.5

Reinforcement filler of low viscosity compounding rubber, special rubber

Suitable for adhesive

E-7: CRS-2103-47 (Tatsumori Ltd.)

Silica surface-treated with 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane

Low dielectric constant, high resistivity

(F) Photopolymerization catalyst:

① Photoinitiator:

② Photosensitizer: 2-Chlorothioxanthone

(Test Example) Property Measurement

(1) sensitivity

Step tablet No. 2 of KODAK Co., Ltd. was covered on the dried resist ink, and evaluated after development in a luminescent solution at 1% Na ₂ CO ₃ solution at 400mj / cm ₂ .

◎: When there are 8 or more stages of undeveloped parts

○: When there are 6 to 7 steps left undeveloped

×: when undeveloped portion remains below 5 steps

(2) developability

After the resist ink was applied to the FR-1 substrate, the resultant was dried for 30 minutes, 35 minutes, 40 minutes, and 50 minutes at 90 ° C., and then evaluated after development in a 1% Na ₂ CO ₃ aqueous solution with a blast furnace at 400mj / cm 2. .

◎: When there is no undeveloped residue at the time of developing after drying at 90 ℃ for 40 minutes

(Circle): After drying for 35 minutes at 90 degreeC, when there is no undeveloped residue at the time of image development

X: After drying at 90 degreeC for 30 minutes, when there exists an undeveloped residue at the time of image development

(3) heat resistance

After applying the resist ink to the FR-4 substrate, it was dried for 20 minutes at 90 ℃, blasted at 300mj / ㎠, developed in 1% Na ₂ CO ₃ aqueous solution to form a pattern, and heat-cured at 150 ℃ 30 minutes After depositing the substrate on which the permanent film was formed by applying a rosin meter plus to a molten solder bath (240-280 ° C), measure the surface state.

◎ ~ ○: When there is no poor adhesion of the surface when immersed 3 times or more for 10 seconds

△ ~ ×: When poor adhesion appears on the surface when immersed two times or less for 10 seconds

(4) hardness

Measured using pencil hardness on a fully cured substrate surface.

◎: 6H or more

○: 6H

×: 6H or less

(5) resolution

A negative film was placed on the dried resist ink, and the ink width remaining on the substrate after development in a 1% Na ₂ CO ₃ aqueous solution by luminescence at 300mj / cm 2 was measured.

(Double-circle): When the circuit of 60 micrometers remains

(Circle): When the circuit of 70 micrometers remains

X: when a circuit of 80 µm remains

(6) electrical insulation

The resist ink was printed on a COMB electrode, completely cured, and left for 510 hours in a constant temperature and humidity chamber at 40 ° C and 95% RH.

○: When insulation resistance is 1012 or more

X: When insulation resistance is 1012 or less

(7) corrosion resistance

After printing and completely curing the resist ink on a COMB type electrode, the resist ink was placed in a constant temperature and humidity chamber at 40 ° C and 95% RH. The resultant was left for 510 hours under the condition of applying DC 100V.

◎ ~ ○: When there is no trace of corrosion on the circuit

△ ~ ×: When the traces of corrosion on the circuit are in dots or lines

The evaluation results of each Example and Comparative Example for the above test items are shown in Table 1 below.

The results in Table 1 show that the resist compositions (Examples 1 and 2) using silica coated with a specific silane coupling agent as the inorganic filler can significantly improve the corrosion resistance of the resist.

The solder resist composition according to the present invention can significantly improve the corrosion resistance of the resist by containing silica coated with a silane coupling agent having a cyclic aliphatic epoxy group in the molecule represented by the formula (1).

Claims (2)

In the solder resist composition of the following composition used to form a solder resist on a printed circuit board, (A) 20 to 60% by weight of carboxyl group-modified epoxy acrylate having an average acid value of 40 to 120 and an average molecular weight of 3,500 to 12,000; (B) 2 to 25% by weight monomer having two or more polymerizable double bonds in the molecule; (C) 7 to 35% by weight of a thermosetting agent having at least one epoxy group in the molecule; (D) 0.05 to 20% by weight of an amine thermal curing agent having active hydrogen in the molecule; (E) 10-40% by weight of at least one filler; And (F) 1 to 20% by weight of a photopolymerization catalyst comprising at least one photoinitiator and a photosensitizer; As a filler, the photosensitive soldering resist composition characterized by using silica coated with the silane coupling agent which has a cyclic aliphatic epoxy group in the molecule represented by General formula (1): [Formula 1] Where R is or ego, n is an integer of 1-6. The photosensitive solder resist composition according to claim 1, wherein silica coated with 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane is used as the filler.