JPS6380594A - Manufacture of mask for soldering - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field for yfu] The present invention relates to a novel method for manufacturing a solder mask for printed wiring boards. More specifically, the present invention relates to a method for producing a solder mask with excellent circuit coverage, which includes a step of applying a specific composition with a specific viscosity and using a specific coating method.

[Problems to be solved by conventional technology and invention]

Screen printing has conventionally been used to form solder masks for printed wiring boards.

However, improvement in resolution has been desired.

As a method with excellent resolution, there is a method in which a liquid element-sensitive composition is applied over the entire surface of a circuit-formed substrate, the solvent is removed, image exposure is carried out, and a resist is formed by a development process.

Known methods for applying the entire surface in this case include the screen printing method, roll coater method, and curtain coater method, but with the former two methods, it is difficult to consistently obtain a sufficiently thick coating film. There is a drawback.

The curtain coater method has the advantage that a relatively thick film can be obtained in a short coating time, but hitherto there has been no satisfactory combination with the photosensitive material to be coated, and improvements have been desired. That is, it is better to apply a thick coating for the purpose of a circuit punching machine, but if the coating is thick, there is a problem that the photosensitive liquid is trapped inside the through hole and cannot be removed during development.

For example, British Patent No. 203.2-39 describes the curtain coating of a resist containing an epoxy acrylate oligomer and an inorganic filler, but this composition has a solder mask with sufficient layer density. However, trichloroethylene and dichloromethane are used as developing solutions, and development cannot be performed with trichloroethane, which is commonly used. Furthermore, the ability to remove the photosensitive liquid inside the through hole was also poor.

When using a photosensitive composition that has poor developability and therefore cannot sufficiently remove the photosensitive solution in the through hole during development, a coating method has been devised to prevent the composition from penetrating into the through hole as much as possible. For example, Tokukai Showa J4 1♂20
Publication No. 23 describes viscosity! 00~/2θθmPa, s (
cps), and it is also stated that by specifying the falling speed of the curtain coating film, it is possible to apply it at a thickness that allows sufficient removal of the composition in the through holes during development. There is. However, the height of the circuit is 0μm
Due to the above reasons, it was desired to apply the coating as thickly as possible in order to sufficiently cover the negative road.

Tokukai Akira again? Publication No. 4,24jg describes a method of curtain coating a thermosetting photosensitive material, but these compositions have poor sensitivity and resolution when applied thickly, making them unsuitable for use as solder masks. I can not use it.

Therefore, in order to solve the above problems, the present inventor conducted various studies and discovered a method for manufacturing a solder mask with excellent performance that has sufficient circuit coverage and good permanent coating properties, and has developed the present invention. reached.

[Means for solving problems]

That is, the gist of the present invention is that (A) a weight average molecule z3 having a polymerizable double bond in the side chain;
o, ooo or more polymer compound, (B) a polymerizable monomer having two or more terminal (meth)acrylic groups, (C) a photopolymerization initiator, and (1)) a heat containing at least inorganic fine particles. A solder that has the process of coating a printed IAH board with a curtain coater to an average dry film thickness of 90 μm or more using a photosensitive liquid in which a plastic photosensitive substance is dissolved and dispersed in a coating bath agent with a viscosity ranging from /00 cps to j00 cps. The problem lies in the manufacturing method of the mask.

The present invention will be explained in detail below.

The first component of the photosensitive composition used in the production method of the present invention is (A) a polymer compound having a polymerizable double bond in its side chain and having a weight average molecular weight of 3θ, 000 or more.

A specific example of this polymer compound is, for example, a (meth)acrylic polymer K containing hydroxyethyl (meth)acrylate or hydroxypropyl (meth)acrylate alone or as a comer. polymers in which (meth)acrylic acid is esterified into the hydroxyl groups of phenoxy resins, polymers in which (meth)allyl groups are etherified into the same hydroxyl groups, polymers in which glycidyl (meth)acrylate is added to the same hydroxyl groups (co)polymer of dially(iso)phthalate and/or triallyl in cyanurate, (co)polymer of glycidyl (meth)acrylate, polymer with (meth)acrylic acid introduced by esterification, carboxyl group-containing polymer Glycidyl (
Polymers in which meth)acrylate has been added, polymers in which a copolymer of maleic anhydride is subjected to an addition reaction with a compound containing both hydroxyl groups and (meth)acrylic groups, and (meth)acrylic acid in partially hydrolyzed vinyl acetate polymers. Examples include polymers in which esterification has been introduced.

Furthermore, a (meth)acrylic polymer containing a polymerized unit represented by general formula (1) is most preferred.

General formula (1) [In the formula, R1 and R2 represent a hydrogen atom or a methyl group, which may be different, and R3 is -0H2(HOH, -1O
H -0H20H2- or -cH,OH,- or -〇H
, OH- indicates OH.

vinegar. ] The first component of the photosensitive composition used in the production method of the present invention is CB) - a polymerizable monomer having two or more terminal acrylic groups. Specifically, diols such as ethylene glycol, tetraethylene glycol,
Nonaethylene glycol, polyethylene glycol, propylene glycol, butanediol, hexanediol, he+sameethylene glycol, dihydroxyethyl ether of bisphenol A, bisphenol tetrabromide A1
Acrylic acid diester or methacrylic acid diester such as dihydroxyethyl ether, cyclohexane dimetatool: trimethylolpropane, pentaerythritol, dipentaerythritol or its Mi form,
(Meta) of polyols with a value of λ or higher such as glycerol, trihydroxyethyl isocyanurate or its derivatives
Acrylic acid ester; reaction product of polyvalent epoxy compounds such as bisphenol A epoxy compounds, phenol novolak epoxy compounds, cresol novolak epoxy compounds and (meth)acrylic acid; reaction products of diisocyanate compounds and diol monoacrylates or methacrylates; Reaction product, reaction product of a diisocyanate compound, diol compound, and diol mono(meth)acrylate; reaction product of a diisocyanate compound, diol compound, and triol di(meth)acrylate; (meth)acrylate compound having a phosphate ester group , specifically, bis(meth)acryloxyethyl phosphate, bis(acryloxyethyl)phenyl phosphate, bis(methacryloxyethyl)butyl phosphate, tris(meth)acryloxyethyl phosphate; silicone-based (meth)acryloxyethyl phosphate; ) acrylate, etc.

Seven or more of these are used. Preferably, (meth)acrylic ester of trihydroxyethyl isocyanurate or its derivative, urethane (
Examples include meth)acrylates.

Furthermore, it is also suitable to add a phosphoric acid (meth)acrylate compound having/having a (meth)acrylic group such as (meth)acryloxyethyl phosphate.

Particularly suitable are compounds represented by the following general formula (It).

General formula (I) C is also 0H20RO or -C! -CB=OH2 (However, at least one third component is (C) a photopolymerization initiator. Specifically, benzoin, benzoin alkyl ethers, anthraquinone derivatives,
benzanthrone derivative, λ, 2-dimethoxy=-phenylacetophenone, /-hydroxycyclohexylphenyl ketone, -monomethyl-(Q-(methylthio)phenyl-2-morpholino-/-flopanone, benzyl derivative, benzophenone derivative, , Z'-bis-dimethylaminobenzophenone, xanthone wandering conductor, thioxanthone wandering conductor, biimidazoles, trichloromethyl-〇-triazines, 3.g, 3:da'-tetra (t
-butylbaroxycarponyl)benzophenone, di-
Components of t-butylperoxyisophthalate and these together with pigments and amine compounds such as dialkylaminobenzoic acid alkyl ether are inorganic fine particles. Specifically, for example, Merck, calcium carbonate, silica, barium sulfate, clay,
Kaolin and other ingredients are used. These can also be suitably used after surface treatment with a silane coupling agent or the like.

If necessary, coloring agents, dew-visible painting agents, flame retardants, antifoaming agents, coating properties improvers, etc. may be added to the thermal polymerization inhibiting material. ) is preferably 70 to -
1Qit%, particularly preferably /j~3! Wataru amount chi, (B)
is preferably 10 to 60 wt%, particularly preferably 30
-30 weight displacement, (C) preferably 0.07 to 10 Mk
%, particularly preferably o, i~a″jjLJ!俤, p) is preferably /!~da!weight fL%, particularly preferably 2O-
It can even be used in a range of 40 liters.

This photosensitive composition has particularly excellent developability and bath-disintegrability with respect to /, /, / -trichloroethane, and can remove the photosensitive liquid that has entered the through holes during application during development.

The coating film formed by the I-box photosensitive composition of the present invention exhibits thermoplasticity, and does not harden, for example, even when the coating film is heated at d' 0 ''C for 2 hours.

On the other hand, when the coating film is thermosetting, the sensitivity and resolution tend to be low, and the storage stability thereof also tends to be poor.

The photosensitive liquid may flow in unnecessarily or the circuit coverage may deteriorate. This thermoplastic photosensitive material has a solid content concentration of 3Q to 6j.
% by weight, preferably ryt.

~! ! It is dissolved or dispersed in a coating solvent with a heavy weight, and at this time, /Qθ~5oocpsK is adjusted.

The coating solvent can be used as long as it has an appropriate boiling point and can dissolve or disperse the composition, such as methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl cellosolve, ethyl cellosolve, butyl cellosolve, cyclohexanone, and cellosolve. Examples include acetate, calpitol, and carpitol acetate.

Although coating is performed, it is necessary that the average dry film thickness on the flat substrate be 4 to .mu.m or more in order to satisfy the coverage of the circuit. It is preferably in the range of 0 to 20 μm, particularly preferably in the range of 0 to 20 μm.

〔Example〕

Next, the present invention will be specifically explained using examples and comparative examples, but the present invention is not limited to the following examples as long as it does not exceed the gist of the invention.

Example / (A) Weight average molecular weight represented by the structural formula Jun) -/ / 70,000 polymer compound t kg cooca, eHch2acca = cn2coucH3
1I+ OH0 (B) Isocyanurate trifunctional acrylate tomo/-
r-"70nics M-326" (Toagosei Kagaku Kogyo ■) / o kg, (C) benzophenone 0.3
9 and Michler's ketone o, ikg, ■) average particle size/
Viscosity u 30 ap at 2°C obtained by dissolving or dispersing 10 kg of μm talc fine powder and 2 kg of phthalocyanine green in 3 kg of methyl cellosolve
Using a curtain coater, apply the photosensitive solution of e to a slit width of 0.
7 dragons, head height 100 dragons, coating speed/θθfrL/M
The solder was applied onto a through-hole printed wiring board. The amount applied before the solvent methyl cellosolve evaporates is 247
It was 09/rrl. Diameter 0. Some photosensitive liquid was injected into the through hole of the ♂. After drying for ♂j''Cj minutes, the back side was also coated in the same manner as above, and dried for ♂j''C3θ minutes.

A photosensitive coating film with almost no stickiness was obtained.

The average film thickness of the flat portion of the substrate after drying was 20 μm. After image exposure with a light intensity of 640 mJ/- using an ultra-high pressure mercury lamp /, /,
/-Trichloroethane at a spray pressure of 2 kg/rrl for 7 minutes. The photosensitive liquid inside the through hole was completely dissolved and removed, and the resolution was also good. After washing and drying, post-exposure with 7 high-pressure mercury lamps of 10 W/an, /j O'C/
Heated for j minutes.

The resulting solder mask on the printed wiring board covered the circuit with a sufficient thickness without uneven coating. i.e. 9
On a circuit with a height of 0 ltm, the thickness was 208 m1 at a part of the corner of the circuit, and it did not peel off even after being immersed in molten solder at 260°C.

Also trichlorethylene, 70% sulfuric acid,! No change was observed on the surface even after the sodium hydroxide solution was injected at 7:00 a.m.

Example (A) Weight average molecular weight represented by the structural formula K) - / 70,000 t kg, (B) Incyanurate system 3
Functional acrylate monomer〇Aronix M-3/! ”(
Toagosei Kagaku Kogyo □□□O-slit) 7 to 9, pentaerythritol triacrylate 3 kg.

(methacryloxyethylphosphny) 0. OJ”k
g, (C) Benzophenone 0.3ky, Michler Ketone o, /kg, GD) Average particle size / μm +7) Merck% powder / Okg and Phthalocyanine Green o, 2k
g was dissolved or dispersed in methyl cellosolve 30~ to obtain a photosensitive liquid having a viscosity e j Ocps at -2t°C.

Coating was carried out on a copper through-hole substrate using a curtain coater under the same conditions as in Example 1 using coating method '4/701/rd containing a solvent. The photosensitive liquid entered into the through hole with a diameter of 0 and cr.

After drying for j minutes, the back side was also applied under the same conditions and dried for 30 minutes, resulting in a photosensitive heavy film with uneven coating and stickiness.It was flat after drying. The average film thickness was !θ. Exposure, development, and post-curing treatments were carried out in the same manner as in Example 1.

The photosensitive liquid inside the through hole had been completely removed. Height 70 a% 4 The circuit was coated with a sufficient thickness, and after soldering, no solder was attached to unnecessary parts. The bath resistance, surface hardness, adhesion, and resolution were also good.

Comparative example/2! Viscosity 1000cpa at °C
Except for the above, the same photosensitive composition as in Example was used, and the coating was applied under the same conditions to give an average film thickness of 70 μm on the flat part of the substrate after drying, but the coating was applied to the side of the circuit with a length of approximately 70 μm. There was a board with blank areas.

Comparative Example A solder mask was formed in the same manner as in Example except that the average film thickness after drying was 30 lbs. Height 90; F”
There was a possibility of peeling at the part where the router mask thickness was below 2ξ on the side of the E circuit, and at the part where it was thinned after soldering.

Comparison example 3 xn”p-equal molecular sound Jθ represented by the structural formula (g))-/
0θ oligomer 73 to 9 0HOOHO pentaerythritol triacrylate 3kg, benzophenone 0.3 to 9, Michler's ketone θ, /kg, talc fine powder 10kg and phthalocyanine green 0.2k
Coating was carried out in the same manner as in Example/ using G. Exposure and developer processing were carried out in the same manner as in Examples, but the removal of the photosensitive liquid in the through holes was incomplete.

Also, the adhesion on the solder circuit was poor.

photo) YD-/-2F” (manufactured by Toto Kasei) with a molecular weight of 3
70. σBisphenol A-based epoxy compound%I)/J
"t9, tetraethylammonium bromide Qj
9. Oligomer 2 obtained by heating acethione, 229 and cyclohexanone 4t11 at /'70°C for 3 hours! 9, -16-xylyl biguanide 2171 Merck 69, cyclohexanone + 20 g and methyl cellosolve 201 A photosensitive liquid dissolved and dispersed in a mixed solvent was coated onto a substrate to a thickness of about 100 liters. This coating film is ♂0
'C It was a thermosetting coating film that hardened when heated for 2 hours. After imagewise exposure at a light intensity of 10 J/'d, the film was developed with cyclohexanone and heated at 733° C. for one hour to obtain a solder mask. Sensitivity was fast, and resolution was also low.

In addition, the most commonly used developer /
Development was not possible with trichloroethane.

〔Effect of the invention〕

According to the present invention, the photosensitive composition of the present invention, which is poor in sensitivity and developability, is coated on a circuit board using a curtain coater to a specific film thickness within a specific viscosity range. It is possible to obtain a solder mask which does not prevent the intrusion of multiple photosensitive liquids into the J-layer, has good circuit removal properties and permanent coating properties, and has excellent through-pole developability at the same time.

Claims (7)

[Claims] (1) (A) a polymeric compound with a weight average molecular weight of 30,000 or more that has a polymerizable double bond in its side chain, (B) a polymerizable monomer that has two or more terminal (meth)acrylic groups, ( C
) A thermoplastic photosensitive material containing at least a photopolymerization initiator and (D) inorganic microparticles is applied to a coating solvent from 100 cps to 5
Using a photosensitive liquid dissolved and dispersed in a viscosity range of 00 cps,
A method for manufacturing a solder mask, which includes the step of coating a printed wiring board with a curtain coater to an average dry film thickness of 40 μm or more. (2) (A) A patent claim characterized in that a polymer compound having a polymerizable double bond in a side chain and having a weight average molecular weight of 30,000 or more contains a polymerized unit represented by general formula (I) in the molecule The manufacturing method according to item 1. General formula (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) [In the formula, R^1 and R^2 represent hydrogen atoms or methyl groups, which may be different, and R^3 is ▲ , chemical formulas, tables, etc. ▼, -CH_2CH_
2- or ▲There are mathematical formulas, chemical formulas, tables, etc.▼. ] (3) (B) The manufacturing method according to claim 1, which contains a compound represented by general formula (II) as a polymerizable monomer having two or more terminal (meth)acrylic groups. General formula (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) [In the formula, R^4 to R^6 are hydrogen atoms, ▲ Numerical formulas, chemical formulas,
Indicates ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼. (However, at least one has a ▲mathematical formula, chemical formula, table, etc.▼or ▲mathematical formula,
There are chemical formulas, tables, etc. ▼ Show. )〕 (4) The manufacturing method according to claim 1, wherein the inorganic fine particles (D) are contained in a range of 15% to 45% by weight based on the solid content. (5) The manufacturing method according to claim 1, wherein the coating is applied to an average dry film thickness of 50 μm or more and 90 μm or less. (6) The method according to claim 1, wherein the polymer compound (A) having a polymerizable double bond in its side chain has a weight average molecular weight of 100,000 or more. (7) The manufacturing method according to claim 1, which uses a photosensitive liquid containing a thermoplastic photosensitive material at a solid content of 40 to 55% by weight.