JPS60131998A - Pretreating solution for plating - Google Patents

Abstract

PURPOSE:To obtain a pretreating soln. for plating improving the adhesive strength of a plated film to the surface of metallized wiring by preparing a mixed soln. contg. sulfuric acid and hydrofluoric acid for treating wiring of metallic paste of W and/or Mo printed and baked on a green sheet having a high Al2O3 content. CONSTITUTION:Wiring of metallic paste of W, W-Mo or Mo is printed on ceramics contg. >=70% Al2O3, sintered, and treated in a pretreating soln. for plating. A mixed soln. contg. 20-50vol% sulfuric acid and 1-5vol% hydrofluoric acid in pure water is used as the pretreating soln. When the pretreating soln. is used, the adhesive strength of a plated Ni or Au film to the metallized surface is improved, no reject is produced, and a plated film having superior resistance, durability and stable quality is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for applying W to ceramics having an Al2O3 content of 70 cm or more.
Or, it relates to a plating pre-treatment solution in which components with fully assembled wiring such as W-Mo or Mo are immersed in a mixed solution, and more specifically, to improve the adhesion of a plating film layer to a metallized wiring surface. This relates to a plating pretreatment solution that measures

Conventionally, ceramics with metallized wiring were prepared by adding a single alkali or single acid to pure water, such as NaOH mixed with pure water, pure water and sulfuric acid, or pure water and hydrofluoric acid, etc., in the pre-plating process. The treatment was carried out by immersing it in the mixed liquid.

When products treated with these solutions were plated with Ni or Au and sintered at 700 to 850°C, blisters often appeared on the plated surfaces. This is W or W
It was determined that the internal gas expanded due to heating due to poor adhesion between the metallized surface of -Mo or Mo, etc. and the plating.

As a result of investigations into various additives for ceramics and metallization, and various tests on treatment liquids before plating, the inventor found that
The present invention was completed by clarifying the cause of this problem.

The present invention is a green sheet with an Al2O3 content of 70% or more, printed wiring with W or W-Mo metal paste, and sintered, or a green sheet with an Al2O3 content of 70% or more.
% or more of wiring printed and baked using the above metal paste on a sintered board, and sulfuric acid at a volume ratio of 20 to 5% to pure water.
0% and 1-5 t of hydrofluoric acid? The present invention provides a plating pretreatment solution that is characterized in that it is processed in a mixed solution.

The present invention will be explained below.

The following investigation results revealed that the cause of blistering after heating due to poor adhesion between the metallized surface and the plating was caused by the plating pre-treatment liquid.

Print wiring on a green sheet with an Al2O3 content of 70 cm or more using a paste prepared with W powder, sinter the board, degrease it, immerse it in the plating pretreatment solution described below, wash it with water, and then dehydrate it. After that, N1 plating was applied and sintering was performed in a reducing atmosphere at 750°C. Examine the sample with a magnifying glass to determine the number of blisters and the fractured surface of the ceramic.

The results were observed using an E and M electron microscope.

Thirty samples of each were investigated.

As is clear from the above table, the mixed solution of single alkali or mono-acid in pure water of Samples 1 to A4 causes blisters or corrodes the ceramic, and cannot be used.

On the other hand, samples A5 to A9, a mixed solution of a complex acid of 20 to 50% sulfuric acid and 1 to 5% hydrofluoric acid in terms of volume ratio to pure water, did not cause any blistering and did not corrode ceramics. We were able to obtain good results with almost no visible signs.

In addition, the volume ratio of sample groups 10 to AI2 to pure water is sulfuric acid of 60% or more and 15% or less, hydrofluoric acid of 6% or more and 0%.
Mixtures of complex acids containing 5% or less caused blistering and slight corrosion of ceramics.

As is clear from the above investigation, this is the reason for limiting the volume ratio of sulfuric acid to 1 to 5% of sulfuric acid and 1 to 5% of hydrofluoric acid to pure water in the present invention. Also, Al
The reason why the 2O3 content is set to 70 or more is because the glass component, which is the matrix in the ceramic, increases and becomes susceptible to corrosion.

Based on the results of this investigation, it was determined that by using a mixture of sulfuric acid and hydrofluoric acid, the corrosive effect of hydrofluoric acid itself on the glass components in the ceramic was suppressed by adding sulfuric acid, and the result was achieved. be done. It is also believed that sulfuric acid and hydrofluoric acid were very effective in removing metalized oxides of W, W--No, or Mo.

By employing the present invention, it was possible to improve the adhesion of the Ni or Au plating layer to the metallized surface, eliminate the occurrence of defects, and also achieve excellent heat resistance, durable quality, and stability.

Examples will be described in detail below.

Example A wiring board was manufactured by printing wiring on a green sheet containing 92% Al2O3 using a paste prepared with W powder, and sintering it at 1550° C. in a mixed atmosphere of hydrogen and nitrogen after removing the resin. After degreasing these substrates and washing them with water, add 50% sulfuric acid and 5 liters of hydrofluoric acid, 50 liters of sulfuric acid and 1% hydrofluoric acid, and sulfuric acid to the pure water in sample stores 5 to A9 shown in Table 1 above. 20 chloride and 1% hydrofluoric acid, 30% sulfuric acid and 2% hydrofluoric acid, 4 sulfuric acid
A treatment solution was prepared by mixing 0% hydrofluoric acid and 3% hydrofluoric acid, and 2,000 pieces of each were immersed in each solution for 2 ml at room temperature, and then washed with water.

Each of these 2000 samples was electrolytically plated with Ni, without jfl.
500 pieces each were plated using Ni plating, electrolytic WfAu plating, and electroless Au plating.At this time, the plating thickness was 4 μm for electroless Ni plating, 4 pm for electroless Ni plating, and 4 pm for electroless Ni plating. : Au plating is 2ttm
, electroless %AuAu plating μm was coated.

The Ni-plated samples were sintered at 850°C, and the Au-plated samples were sintered at 850°C in a mixed atmosphere of hydrogen and nitrogen.

When 500 pieces of each of the above 20 types were inspected for blistering, there were no defects, and it was reported that the durability of the assembled product assembled with the IC element was good in an actual machine test.

The present invention can be applied to all products that have the above-mentioned metallized surface on a ceramic having an Al2O3 content of 70% or more and are coated with plating.

Claims (1)

[Claims] Wiring is printed and sintered using W or W-Mo based or Mo metal paste on a green sheet with an Al2O3 content of 70% or more, or wiring is printed with the above metal paste on a sintered substrate with an Al2O3 content of 70% or more. A pretreatment solution for plating, characterized in that the printed and baked product is treated in a mixed solution of 20 to 50% sulfuric acid and 1 to 5% hydrofluoric acid in terms of volume ratio to pure water.