JPH0125790B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resist ink for chemical plating (for electroless metal plating), which has particularly excellent printability, and has excellent adhesion of cured film, chemical resistance (especially resistance to electroless copper plating liquid, and heat resistance). Our objective is to provide resist inks for chemical plating that are excellent for electroless metal plating on electrically insulating substrates.Precious metals such as Pd, Au, and Pt, which act as catalysts for the plating reaction, are placed on the substrate. This can be achieved by attaching the catalyst and immersing it in an electroless plating solution.There are two main ways to form a desired pattern on a printed circuit board using these methods.On the other hand, a plating catalyst can be used to form a desired pattern on a printed circuit board. The so-called full-additive method involves forming a circuit on a printed circuit board using only electroless metal plating by selectively attaching or exposing the copper-clad laminate to the copper-clad laminate. This is a so-called semi-additive method in which a conductor is formed in a hole part by electroless metal plating.In the present invention, when applying a conductor to a through-hole part by electroless metal plating in the latter method, the conductor is formed on a substrate by an etching method. This relates to resist ink that protects conductor patterns on printed circuit boards.Generally, the film thickness of conductor circuits on printed circuit boards is 30~30~
35μm is required. Furthermore, the characteristics of the electroless plated film forming this conductive circuit are generally required to have an elongation rate of 3% or more and a tensile strength of 21 kg/mm ² or more as proposed by the American Printed Circuit Board Association (IPC). Electroless metal plating films that meet this requirement generally have a pH of 12 to 13.
It can only be obtained in a strong alkaline bath (60°C to 80°C) at 20°C, and the deposition rate of electroless metal plating is about 0.5 to 5 μm/h, so 30 to 35 μm
In order to obtain the desired thickness, it is necessary to plating for a long time. Regarding the manufacturing method of a printed circuit board in which a circuit is formed by electroless metal plating and the resist ink used therefor, the following proposals (1) and (2) have been made, for example. (1) Apply resist ink containing an oxidizing agent to areas other than the desired pattern formation area, and perform the plating pretreatment process base.
There is a method of oxidizing Sn ⁺¹ to form Sn ⁺² without attaching Pd. Representative examples of this method include JP-A-48-76740, JP-A-48-24924,
These are Japanese Patent Application Laid-open No. 114067/1983 and Japanese Patent Publication No. 47/2001. (2) There is also a method of applying a sparse resist ink to areas other than the desired pattern formation area to prevent electroless metal plating from adhering. This method is
-2479 and JP-A-47-23859. In addition, as a proposal for materials with sparse properties,
There are No. 17099 and Special Publication No. 50-17100. However, the resist ink described in (1) above contains an oxidizing agent in the resist, which is relatively weak against alkaline solutions and dissolves into the plating solution, causing deterioration and decomposition of the solution. Hydrophobic resists containing wax or wax (2) have the drawback of not being able to withstand the high temperatures and strong alkalis during plating, resulting in softening and deformation, and leaching into the plating solution. In addition, all of these resist ink films have poor heat resistance, so when used for printed circuit boards, they have the drawback of blistering of the resist ink and peeling of adhesives from insulating substrates and conductors during the soldering process. A first object of the present invention is to provide a resist ink composition for chemical plating that forms a resist film that can withstand long-term immersion in an electroless metal plating bath solution. It is an object of the present invention to provide a resist ink composition that has excellent printability as a resist ink and excellent heat-resistant adhesion as a resist film. The above purpose uses (a) epoxy resin, (b) aromatic amine curing agent for epoxy resin, (c) imidazole curing agent for epoxy resin as essential components, (d) organic solvent, and (e) thixotropic This is achieved with a resist ink composition for electroless metal plating, which is characterized by adding a filler, (f) a filler, and (g) a chemical plating inhibitor. The epoxy resin (a) used in the present invention has on average two or more epoxy groups per molecule, such as polyhydric phenols such as bisphenol A, halogenated bisphenol A, catechol, resorcinol, etc. or polyglycidyl ether or polyglycidyl ester obtained by reacting a polyhydric alcohol such as glycerin with epichlorohydrin in the presence of a basic catalyst; These include epoxidized polyolefin, epoxidized polybutadiene, dicyclopentadiene oxide, or epoxidized vegetable oil, which are epoxidized by an oxidation method. More specifically, Dow Chemical's DEN431, an epoxy novolak resin,
DEN438 and Shell Epikote152, Epikote154
was good. Curing agents for epoxy resins include ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, tripropylenetetramine, dihexamethylenetriamine, trimethylhexamethylene, metaxylenediamine, dimethylaminopropylamine, diethylaminopropylamine. ,
Aliphatic primary and secondary amines such as 1-amino-3-aminoethyl-3.5.5-trimethylcyclohexane, aliphatic primary and tertiary amines such as diethylaminopropylamine and N-hydroxyethyldiethylenetriamine, piperazine, Cyclic amines such as N-aminoethylpiperazine and pyridine, metaphenylenediamine, 4.4'-diaminodiphenylmethane, 4.4'diaminodiphenyl sulfone,
Aromatic amines such as 4.4'-diaminodiphenyl oxide, 4.4'-diaminodiphenylimine, biphenylene diamine, and modified aromatic amines such as their hydroxyethylated products and adducts with glycidyl ether, dicyandiamide, melamine, NN′-diallylmelamine, hexamethoxymethylmelamine, triallyl cyanurate, benzoguanamine, tetramethylguanamine, and
imidazole, 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole,
2-ethylimidazole, 2-ethyl, 4-methylimidazole, 2-undecaneimidazole,
2-heptadecanimidazole, 1-benzyl-
2-methylimidazole, 1-vinyl, 2-methylimidazole, benzimidazole, 1-(2
-carbamylethyl)-imidazole, 1-(2-
carbamyl)-2ethyl-4-methylimidazole, 2-allyl 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenyl-
4.5-di-(cyanoethoxymethyl)imidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4.5-dihydroxymethylimidazole, 2-methylimidazole isocyanuric acid adduct, 2-phenylimidazole・Isocyanuric acid adduct, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole,
Imidazole compounds such as 1-azinethyl-2-ethyl-4-methylimidazole, 2-methyl-4-ethylimidazole trimesic acid adduct,
Also, there are complexes between these imidazole compounds and metal salts or organic acids. moreover,
BF ₃・amine complex compound, benzyldimethylamine, NNN′.N′・tetramethyl-1,3-butanediamine, quaternary ammonium salt, stannous octoate, 2.4.6-tris(dimethylaminophenol), tetramethyl Guanidine, methyl hymic anhydride, phthalic anhydride, maleic anhydride, polyazelaic anhydride, polysebamic anhydride,
Dodecenyl succinic anhydride, etc. Among these hardeners, the cured coating film of resist ink using a combination of (b) aromatic amine type (including modified aromatic amine) and (c) imidazole type hardener has excellent plating resistance. For 100 parts by weight of epoxy resin,
Good results were obtained when the former was added in an amount of 0.5 to 1.5 equivalents per equivalent of the epoxy resin, and the latter was added in an amount of 5.0 to 30 parts by weight. (a) As the organic solvent, one that mixes and dissolves the epoxy resin and the curing agent for the epoxy resin, and takes into consideration the general properties of the ink, is easy to use with a low volatility and a boiling point of about 100° C. or higher. For example, i-butyl alcohol, n-butyl alcohol, methylisobutyl carbitol, cyclohexanol,
n-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, amyl acetate, methyl amyl acetate, ethyl lactate, butyl lactate, methyloxytol acetate, oxytol acetate, butyloxytol acetate, methyloxytol , oxytol, butyl oxytol, methyl dioxytol, dioxytol, butyl oxytol, methyl n-propyl ketone,
Examples include methyl n-butyl ketone, methyl-iso-butyl ketone, diisobutyl ketone, cyclohexanone, isophorone, diacetate alcohol, nitromethane, and nitroethane. Epoxy resin, curing agent for epoxy resin, and if necessary, thixotropic agent, organic solvent, and chemical plating inhibitor are mixed, dissolved, and dispersed in appropriate amounts, and the viscosity is adjusted to 3,000 to 10,000 poise (20°C, B-type viscometer, 1 rpm). Add as much organic solvent as possible. (e) A thixotropic agent is used to improve the printability of resist ink. As a thixotropic agent, inorganic ultrafine powder such as SiO ₂ is appropriately added to improve the thixotropic index (viscosity measured at 100 rpm with a B-type viscometer/1 rpm rotation speed) of a resist ink with good printability.
(viscosity measured at) obtain a value of 20 to 40. (f) The filler improves the printability of resist ink,
The aim is to improve adhesion and chemical plating solution resistance when used as a resist film. Filling materials include talc, mica, SiO ₂ , TiO ₂ ,
Add 3 to 40 parts by weight of inorganic fine powder such as CaCO ₃ . If more than 40 parts by weight is added, the coating film forming ability will be poor, and if less than 3 parts by weight, the adhesion of the cured film will be poor and both cannot be put to practical use. When a filler with a particle size of 10 μm or less is used, particularly a filler with a particle size of 2 μm or less, the chemical plating solution resistance of the cured resist coating film is significantly improved. (g) The chemical plating inhibitor prevents the chemical plating solution from penetrating into the resist coating, maintains the adhesion between the base material and the resist coating, and prevents chemical plating from forming on the resist coating. is the aim. As the chemical plating inhibitor, triazole, 1.2.3-benzotriazole, 4-methylbenzotriazole, thiourea, 2-methylcaptobenzothiazole, etc. are used alone or in combination. The preferred range of addition amount is 0.1 parts by weight for 100 parts by weight of the epoxy resin.
~5.0 parts by weight; if it is less than 0.1 parts by weight, there is no effect; if it exceeds 5.0 parts by weight, the chemical plating inhibitor in the resist coating will be eluted into the plating bath, and the plating reaction will stop. In addition to the above (a) to (g), (h) a coloring agent and (i) an antifoaming agent may be added alone or in combination as necessary. (h) Colorants include pigments such as phthalocyanine blue and phthalocyanine green. (i) An antifoaming agent is added to remove air bubbles that are entrained during resist ink printing. As an antifoaming agent,
Use silicone oil, etc. The above resist ink components are kneaded using a mulch machine and kneaded using three rolls. Specific examples of the present invention are shown below. Example 1 100 parts by weight of Epicoat 152 (manufactured by Ciel Chemical, epoxy equivalent 175) as an epoxy resin, 10 parts by weight of L-1 (manufactured by Nippon Talc) with an average particle size of 2 μm as a talc powder for filler, phthalocyanine as a coloring agent 2 parts by weight of green (special grade reagent), 1 part by weight of silicone oil SC-5540 (manufactured by Shin-Etsu Chemical) as an antifoaming agent, ultrafine silicon oxide powder Aerosil as a thixotropic agent
A380 (manufactured by Nippon Aerosil KK) 3 parts by weight of resist ink components are kneaded using a mulch machine, and further kneaded using three rolls. This will be used as the base resin. Next, Epicote 152, 100 parts by weight, talc powder L
-1, 10 parts by weight of phthalocyanine green, 2 parts by weight of silicone oil SC-5540, 1 part by weight Aerosil A380, and 12 parts by weight of resist ink components were kneaded using a sieve machine and further kneaded using three rolls. This will be used as the base resin. Base resin, alone or mixed in appropriate amounts, and aromatic amine curing agent, Adeka EH 1013.
(manufactured by Asahi Denka KK, active hydrogen equivalent: 64) and imidazole curing agent 2E4MZ (manufactured by Shikoku Kasei KK) were used alone or in combination, and the added amounts were varied. An amount of n that makes the index 20 to 40 and the viscosity 3000 to 10000 poise (B-type rotational viscometer, 1 rpm 20℃)
-Adjust by adding butyl cellosolve. Copper-clad glass epoxy board (manufactured by Hitachi Chemical)
The above resist ink composition was printed by screen printing on a printed circuit board on which a pattern with a conductor width of 0.3 to 10 mm and a conductor interval of 0.7 to 5 mm was formed so that a part of the conductor pattern was exposed. This is 130
It was hardened by placing it in a heating oven for 30 minutes at ℃. The thickness of the resist coating is 18 to 25 μm. Next, it was immersed in the chemical copper plating solution shown below for 10 hours.

[Table] Water all into 1〓
An automatic control device is installed in the plating liquid tank to monitor the Cu ⁺² concentration, PH, formalin concentration, and
The EDTA concentration was kept constant. Next, the substrate was taken out of the plating solution, washed with water, and then dried in a heating oven at 120°C for 20 minutes. Hand-draw a lattice on the paint film with a sharp cutter knife at 1mm pitch, and then apply Sellotape to this area, then peel off the Sellotape at once in a 45-degree direction.
The state of peeling of the cross-cut resist ink coating was observed. (Cross-cut cellotape test)
The test results are as shown in Figure 1, when an aromatic amine curing agent and an imidazole curing agent were used together, and
The aromatic amine curing agent is 0.3 to 1.5 equivalents per 1 epoxy equivalent of the epoxy resin, and the imidazole curing agent is added to 100 parts by weight of the epoxy resin.
Only combinations of curing agents added in amounts of 5 to 30 parts by weight did not cause peeling of the resist coating. On the other hand, when an aromatic amine-based curing agent or an imidazole-based curing agent is used alone or in combination as a curing agent for resist ink, peeling occurs in the resist coating unless the combination of the above-mentioned curing agent addition amounts is used. Ta. In particular, when an aromatic amine curing agent is used alone, the plating solution enters from the interface between the resist coating and the copper pattern of the printed circuit board, causing peeling of the resist coating. On the other hand, when imidazole-based curing agents are used alone, the toughness of the resist coating film is insufficient.
When cross-cutting with a sharp cutter knife at 1mm pitch, the resist coating often peels off. In addition, the board whose resist coating did not peel off in the cross-cut sellotape test was further placed in a solder bath at 260°C for 20 seconds with the resist coating in contact with the solder (soldering heat resistance test). No peeling or cracking occurs in the paint film. Example 2 The base resin described in Example 1 was mixed alone or in an appropriate amount, and ADEKA EH- was added as a hardening agent.
1.3.5− Using 1013 and 2E4MZ alone or in combination and varying the amount added, and further as a plating inhibitor.
E _P 152 in benzotriazole based resin
Add 1 part by weight to 100 parts by weight, and then add an appropriate amount of n-butyl cellosolve to obtain a printable resist ink with a thixotropic index of 20 to 40 and a viscosity of 3000 to
Adjust to 10,000 poise (B type rotational viscometer 1 rpm 20℃). A resist ink was printed and cured on a substrate on which a conductive pattern was formed using the same method as in Example 1, and the resistance of the resist coating to chemical copper plating was evaluated by a cross-cut cellophane tape test. The thickness of the resist coating is 10 to 15 μm. As shown in Figure 2, the test results show that an aromatic amine curing agent and an imidazole curing agent were used in combination, and the aromatic amine curing agent was used in a ratio of 0.3 to 1.5 per 1 epoxy equivalent of the epoxy resin (E _P 152). Only combinations of curing agents in a range of 5 to 30 parts by weight of an imidazole curing agent per 100 parts by weight of epoxy resin did not cause peeling of the resist coating. On the other hand, when an aromatic amine type curing agent or an imidazole type curing agent was used alone or in combination as a curing agent for the resist ink, peeling occurred in the resist coating film except for the combination of the above-mentioned curing agent addition amounts. Furthermore, the substrates whose resist coating did not peel off in the cross-cut sellotape test were subjected to a soldering heat resistance test, but no peeling or cracking occurred in the resist coating. From the above study results, by adding a chemical plating inhibitor, it is possible to form a resist coating film that is thinner than in Example 1 and that can withstand chemical copper plating solution. Example 3 80 parts by weight of the base resin described in Example 1, 20 parts by weight of the base resin described in Example 1, Adeka
Add 0.85 parts by weight of 4-methylbenzotriazole as a plating inhibitor and 1.5 parts by weight of n-butyl cellosolve to 31 parts by weight (1.0 equivalent) of EH-1013 and 5.5 parts by weight of 2E4MZ, mix well, and add this to resist ink. And so. A cross-cut Scotch tape test and a solder heat resistance test were carried out to check the chemical plating liquid resistance of the resist coating using the same method as in Example 1, but no peeling, blistering, or cracking of the resist coating occurred. The thickness of the resist coating film at this time was 11 μm. Example 4 90 parts by weight of the base resin described in Example 1, 10 parts by weight of the base resin described in Example 1, Adeka
EH-551 (aromatic amine curing agent manufactured by Asahi Denka KK,
Active hydrogen equivalent: 104) 55.5 parts by weight (0.8 equivalent), 2
- 10 parts by weight of phenylimidazole (manufactured by Shikoku Kasei KK), 1.3 parts by weight of triazole as a plating inhibitor, and 2.0 parts by weight of n-butyl cellosolve were added and thoroughly mixed to prepare a resist ink. A cross-cut Scotch tape test and a solder heat resistance test were conducted to check the chemical plating liquid resistance of the resist coating using the same method as in Example 1, but no peeling, blistering, or cracking of the resist coating occurred. The thickness of the resist coating film at this time was 13 μm. Example 5 55 parts by weight of the base resin described in Example 1, 45 parts by weight of the base resin described in Example 1, Adeka
EH-531 (aromatic amine curing agent manufactured by Asahi Denka KK,
Active hydrogen equivalent 88) 36.0 parts by weight (0.5 equivalent), 2E4MZ
20 parts by weight, 0.83 parts by weight of thiourea as a plating inhibitor, and 3 parts by weight of n-butyl cellosolve were added and thoroughly mixed to prepare a resist ink. A cross-cut Scotch tape test and a solder heat resistance test were conducted to check the chemical plating liquid resistance of the resist coating using the same method as in Example 1, but no peeling, blistering, or cracking of the resist coating occurred. The thickness of the resist coating film at this time was 13 μm. Example 6 20 parts by weight of the base resin described in Example 1, 80 parts by weight of the base resin described in Example 1, Adeka
Add 11.9 parts by weight (0.4 equivalents) of EH-1013, 25 parts by weight of 2E4MZ, 1.6 parts by weight of 2-methylcaptobenzothiazole as a plating inhibitor, and 2 parts by weight of n-butyl cellosolve, mix thoroughly, and add this. It was made into a resist ink. A cross-cut Scotch tape test and a solder heat resistance test were conducted to check the chemical plating liquid resistance of the resist coating using the same method as in Example 1, but no peeling, blistering, or cracking of the resist coating occurred. The thickness of the resist coating film at this time was 13 μm. Comparative Example 1 85 parts by weight of the base resin described in Example 1, 15 parts by weight of the base resin described in Example 1, Adeka
31.2 parts by weight (1 equivalent) of EH-1013 and 2.8 parts by weight of n-butyl cellosolve were thoroughly mixed to form a resist ink. Using the same method as in Example 1, a cross-cut Scotch tape test and a soldering heat resistance test were conducted to check the resistance of the resist coating to chemical plating liquid.
The resist coating film peeled off in the cross-cut Scotch tape test. Furthermore, after the solder heat resistance test, blistering occurred in the resist coating. The thickness of the resist coating film at this time was 24 μm. Comparative Example 2 100 parts by weight of the base resin described in Example 1
5 parts by weight of 2E4MZ and 1.5 parts by weight of n-butyl cellosolve were thoroughly mixed to prepare a resist ink. Thereafter, the resist coating film was subjected to a cross-cut cellophane tape test and a soldering heat resistance test to check the chemical plating liquid resistance using the same method as in Example 1, but the resist coating film peeled off in the cross-cut cellophane tape test. Furthermore, after the solder heat resistance test, blistering occurred in the resist coating. The thickness of the resist coating film at this time was 23 μm. As explained above, the resist ink composition for chemical plating of the present invention can be prepared by combining an aromatic amine curing agent and an imidazole curing agent or by adding a chemical plating inhibitor to an epoxy resin.
It has excellent chemical plating solution resistance and good solder heat resistance, and can be applied to the manufacture of printed circuit boards by the additive method.

[Brief explanation of drawings]

FIG. 1 shows the experimental results of Example 1, and FIG. 2 shows the experimental results of Example 2. 1, 1': Range of curing agent addition amount that did not cause peeling or blistering in the resist coating after the cross-cut Sellotape test and soldering heat resistance test, 2, 2':
The range of curing agent addition amount that caused peeling and blistering in the resist coating.

Claims (1)

[Claims] 1 (a) The blending ratio of epoxy resin is 100 parts by weight, (b)
The blending ratio of aromatic amine curing agent for epoxy resin is 0.5 to 1 epoxy equivalent of epoxy resin.
1.5 equivalent, (c) blending ratio of imidazole curing agent for epoxy resin is 5.0 to 30 parts by weight, (d) filler, (e)
The proportion of the thixotropic agent and (f) organic solvent is such that the resist ink has a thixotropic index of 20 to 40 and a viscosity of 3000 to 10000 Poise at 20°C (1 rpm using a B-type rotational viscometer). Characteristic resist ink composition for chemical plating. 2 (a) The blending ratio of epoxy resin is 100 parts by weight, (b)
The blending ratio of aromatic amine curing agent for epoxy resin is 0.5 to 1 epoxy equivalent of epoxy resin.
1.5 equivalent, (c) blending ratio of imidazole curing agent for epoxy resin is 5.0 to 30 parts by weight, (d) filler, (e)
The blending ratio of the thixotropic agent and (f) organic solvent is such that the thixotropic index of the resist ink is 20 to 40, and the viscosity at 20°C is 3000 to 10000 Poise (B-type rotational viscometer 1 rpm), g) A resist ink composition for chemical plating, characterized in that the chemical plating inhibitor is a compound selected from triazole, 1.2.3-benzotriazole, 4-methylbenzotriazole, thiourea, and 2-mercaptobenzothiazole. thing.