JPH01251785A - Aftertreatment for printed wiring board - Google Patents

Abstract

PURPOSE:To reduce copper migration greatly by immersing a printed wiring board in a hot pressurized solution containing metal deactivators or copper- hazard preventives after formation of a circuit pattern. CONSTITUTION:As processing chemicals, a solution is use in which one or more kinds selected from triazole compounds, imidazole compounds, tetrazole compounds, aromatic secondary amine compounds, aromatic hydrazine compounds and oxine compounds are dissolved or suspended in water or an organic solvent. To process, a wiring board is immersed in the solution, after which it is pressurized or heated under pressure. The processing temperature ranges from room temperature - 180 deg.C, preferably 80-140 deg.C. The pressure ranges from 1-100 atmospheric pressure, preferably 1-20 atmospheric pressure. The concentration of the processing solution ranges from 0.1-30% (wt.%), preferably 1-10%.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for post-processing a printed wiring board to obtain a printed wiring board with excellent electrolytic corrosion resistance.

(Prior Art) Printed wiring boards have been widely used in electronic circuits. There are a wide variety of types and forms, such as the subtract method in which circuits are formed by etching from copper-clad laminates, the additive method in which circuits are formed by electroless plating, and flexible printed wiring boards, but copper foil circuits are usually made using adhesives. It is fixed to the board via. Generally, a rubber adhesive is used as the adhesive because it has excellent adhesion to copper.

(Problem to be solved by the invention) As the density of printed wiring boards increases, the spacing between circuit patterns is becoming narrower, and the occurrence of puntlants due to copper migration between patterns under an electric field has become a problem. Ta. In particular, when the adhesive layer exposed between circuits is made of a rubber composition, it is easy to migrate under high temperature or high humidity, and Puntlant is likely to occur at the resist interface between patterns, the adhesive, and the resist bulk. , this may form a bridge, resulting in short circuit or burnout.

The present invention provides a treatment method for suppressing such copper migration in printed wiring boards.

(Means for Solving the Problems) The present invention involves forming a circuit pattern and then immersing a printed wiring board in a heated and pressurized solution containing a metal deactivator or a copper damage inhibitor. This makes it possible to significantly reduce copper migration.

As processing agents, triazole compounds, imidazole compounds, tetrazole compounds, aromatic secondary amine compounds,
A solution in which one or more selected from aromatic hydrazine compounds and oxine derivatives is dissolved or suspended in water or an organic solvent is used.

The processing method is to immerse the wiring board in a solution and then apply pressure or heat and pressure. The processing temperature is room temperature to 180°C, preferably 8°C.
0 to 140°C, pressure 1 to 100 atm, preferably 1
~20 atmospheres.

This is because if the processing temperature is below room temperature, it is difficult for the processing agent to penetrate into the resist interface between the patterns and into the adhesive, and if it is above 180° C., there is a risk of deteriorating the wiring board itself.

If the pressure is less than 1 atm, the processing agent will not diffuse or penetrate into the resist interface between patterns or the adhesive sufficiently;
If the pressure exceeds 0 atmospheric pressure, equipment restrictions will occur.

The concentration of the treatment liquid is 0.1 to 30% (same below weight%),
Desirably, it is about 1% to 10%.

If it is less than 0.1%, the effect of preventing migration will be small, and if it exceeds 30%, the treated surface will tend to become non-uniform, which will cause problems in post-processing. The solution may be impregnated with one or more treatment agents, and one or more solutions may be used multiple times.

Triazole compounds that can be used in the present invention include 1,
2.3) Riazole, 1,2,41-riazole and their derivatives such as 1 phenyl-1°2.3 triazole, 2 phenyl-1,2,3 triazole, 1 phenyl-1,2,4) riazole, 3 -(N salicyloyl)amino-1,2,4 triazole, benzotriazole,
Tolyltriazole, salts of tolyltriazole, benzotriazole-2-methylimidazole adducts, etc.

As triazine compounds, 1,2.2 triazine, 1
, 2.4) Lyazine, 1,3.5) Lyazine and their derivatives such as 2-dibutylamino-4,6-dimethyl-1,3.5) Lyazine, 2-vinyl-4,6-diamino-1.3.5) Lyazine - Contains isocyanuric acid adducts.

Examples of imidazole compounds include 2-methylimidazole,
Examples include 2-ethyl-4-methylimidazole, 1-benzine-2-methylimidazole, 2-phenymidazole, 2-phenyl-4-methylimidazole, undecylimidazole, and derivatives thereof, such as 2-mercaptobenzimidazole and 2-mercaptomethylbenzimidazole.

Examples of aromatic amine compounds include octylated diphenylamine, P-(P)luenesulfonylamide) diphenylamine, NN' di2naphthyl P-phenylenediamine, Nphenyl N' isopropyl P-phenylenediamine, NN'' diphenyl P-phenylenediamine, etc. There is.

As an oxy compound, oxine (8oxyquinoline)
, 7 bis (2 ethylhexyl) amino methylene 8 hydroquinoline, 7 bis (n butyl) amino methylene 8 hydroxyquinoline, 7 bis (n hexyl) amino methylene 8
Hydroxyquinoline, etc.

Tetrazole compounds include tetrazole and its derivatives such as phenyltetrazole, mercaptotetrazole [bis(2ethylhexyl)aminomethylene],
2,3.4tetrazole, [bis(n-butyl)aminomethylene)1,2,3゜4tetrazole, [bis(nhexyl)aminomethylene)1.2,3.4tetrazole,
[Bis(n-octyl)amiminethylene) 1. 2.
3. 4-tetrazole, etc.

The solvent after treatment can be water or organic solvents such as methyl ethyl ketone, toluene, xylene, methanol, ethanol, isopropanol, cellosolve, cellosolve acetate, tomethylformamide, dimethyl sulfoxide, etc. Suspend.

(Function) It has been known for a long time that transition metals or their metal salts have a specific catalytic effect on the oxidative deterioration of polymers, and in order to suppress these effects, they are added to polymers and used as so-called copper damage inhibitors. , or metal deactivators are known.

(Osawa et al.: Koka 70 (12) 2364, ゛ 67, R
, HSHANSE Netal: J, Polym.

5u(A), 587-609' 64, etc.) The above action is fundamentally different from the phenomenon of copper migration under a humid electric field.

Copper migration is a phenomenon in which copper in the circuit electrode (anode) dissolves and ions migrate to the opposite electrode and precipitate. It is presumed that copper acts on copper to dissolve it, suppress its elution, or capture and inactivate eluted ions.

Example 1 An additive wiring board substrate was prepared by coating a glass-based epoxy resin laminate with an adhesive solution containing acrylonitrile butadiene rubber as a main component, alkylphenol, and an epoxy resin, and heating and curing the adhesive solution. , in circuit/space = 0.2510.25 by electroless plating
A comb-shaped pattern of m was created.

This test wiring board was immersed in a methyl ethyl ketone solution containing 5% benzotriazole, heated and pressurized at 120° C. and 2 atm for about 1 hour, and then air-dried and dried at 120° C. for 10 minutes.

Electrolytic corrosion tests are conducted at 65°C and 90% RH.
Under high humidity conditions, a voltage of DClooV was applied between the electrode circuits and current was continuously applied, and the formation of puntlant due to copper migration between the electrodes was monitored.

In order to prevent the circuit surface from being directly affected by the adhesion of water droplets under the above test environment, a solder resist waterproof film was screen printed on the entire surface before the test to protect the circuit surface. Table 1 shows the occurrence of dendrites.

Further, the time until short circuit occurred was more than 300 hours.

Example 2 A treatment was carried out in the same manner as in Example 1, using as a treatment agent a solution prepared by dissolving and suspending about 1% of 2-vinyl-4.6-diamino-1,3.5-triazine in water. Table 1 shows the occurrence of dendrites. Furthermore, the time until short circuit occurred was over 300 hours.

Example 3 A wiring board was heated and pressurized at 130° C. and 3 atm with a 2% cellosolve acetate solution of 2-methylimidazole, air-dried, and then dried at 130° C. for 30 minutes.
The procedure was the same as in Example 1, except that the sample was heated and pressurized with a methanol solution, air-dried, and then dried at 100° C. for 10 minutes. Table 1 shows the occurrence of dendrites. Furthermore, the time until short circuit is 300
It was more than an hour.

Example 4 [Bis(2nhexylnoaminomethylene] 1°2.3
．． 4-tetrazole and 3-(N-salicyloyl)amino-
A suspension of 1,2,4 triazole at a concentration of 1% was made into a suspension, and this was treated as a treatment agent in the same manner as in Example 1).

Table 1 shows the occurrence of dendrites. The time until short circuit occurred was over 300 hours.

Comparative Example In Example x, the heating and pressure treatment of the benzotriazole solution was not performed, and only resist printing was tested. Table 1 shows the occurrence of dendrites. The time until short circuit is 1
It was 50 hours.

○: No dendrant, Δ: Slight dendrant ×: Significant occurrence of puntlant.

(Effect of the invention)

Claims (2)

[Claims] 1. The printed wiring board on which the circuit pattern has been formed is prepared by dissolving one or more selected from triazole compounds, triazine compounds, imidazole compounds, tetrazole compounds, aromatic secondary amine compounds, aromatic hydrazine compounds, and oxine compounds in water or an organic solvent. A method for post-processing printed wiring boards, which comprises immersing them in a suspended solution. 2. The temperature of the immersion treatment is room temperature to 180℃, and the pressure is 1 to 10℃.
Claim 1: Pressurizing or pressurizing and heating at 0 atmospheric pressure
Post-processing method for printed wiring boards as described in Section 3.