JPH114063A - Plating pre-treatment method of ceramic wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a part connecting plating film which is free from plating deposition fault and a pattern failure caused by impurities such as glass or the like by a method wherein masking is carried out corresponding to the amount of a glass component which oozes out onto a metallized layer, and the glass component is removed by liquid honing. SOLUTION: A mask divided into areas corresponding to the amount of a glass component which oozes out onto a metallized layer is prepared. In an area 4 where an oozing glass component is large in amount, liquid honing is carried out with a higher pressure to remove the glass component from the area 4. In an area 5 where an oozing glass component is small in amount, liquid honing is carried out with a lower pressure to remove the glass component from the area 5. As mentioned above, liquid honing conditions are changed for each area, whereby an Ni/Au plating film free from plating deposition fault caused by impurities such as glass or the like can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for pre-plating a ceramic wiring board on which components such as LSi are mounted, and to form a plating film for component connection without plating non-precipitation or pattern loss due to impurities such as glass. And a plating pretreatment method that does not cause plating deposition outside the metallized area.

[0002]

2. Description of the Related Art Input / output terminals of a ceramic wiring board include:
A component such as LSi is mounted and a plating film is formed for connection. In general, this plating film is formed by electroless Ni /
Au plating.

In the prior art plating pretreatment method, there is a method of removing a glass component by a method of performing surface grinding with a grindstone and blasting with abrasive grains.

[0004]

However, on the metallized surface of the sintered ceramic wiring board, there is an exudation of a glass component, which is a ceramic component, onto the metallized surface and adhesion of ceramic foreign substances that adhere during sintering.
In particular, the amount of exudation of the glass component has a variation in the amount of exudation within the substrate, and it is extremely difficult to remove the exudation by liquid honing. However, the pattern is lost, and conversely, it remains as a foreign substance in a large number of areas, and the subsequent plating film cannot be formed, and the plating does not deposit.

[0005] Further, there is a problem in that the liquid honing is strongly performed, thereby damaging the ceramic portion without metallization, and plating is deposited on the ceramic in the subsequent plating.

The present invention solves the above-mentioned problems, and forms a plating film for component connection without plating non-precipitation or pattern loss due to impurities such as glass, thereby suppressing plating deposition on the ceramic outside the metallized area. It is to provide a pre-processing method.

[0007]

According to the present invention, in order to achieve the above-mentioned object, a mask having an area divided according to the difference in the amount of exudation of the glass component onto the metallized metal is prepared. In an area where much oozing occurs, the glass component in that portion is removed by increasing the pressure of the liquid honing (1 to 3 kgf / cm ² ). Further, in an area where the amount of exudation of the glass component is small, the pressure of the liquid honing is reduced (1 kgf / cm ² or less) to remove the glass component in that portion. By changing the conditions of the liquid honing for each area in this manner, a Ni / Au plating film free of plating non-precipitation due to impurities such as glass can be formed without losing metallization. As a result, a plated film having high component connection reliability such as LSi can be obtained.

Further, since the liquid honing is selectively performed on the metallized area, damage due to honing on the ceramic surface can be reduced, and deposition of plating on the ceramic can be avoided.

In the pretreatment method for plating according to the present invention, metallization due to liquid honing and damage to the ceramic are reduced, and sintering of the glass component on the metallized surface of the ceramic wiring board and sintering occurring during sintering. Can be completely removed.
That is, by performing the masking, it is possible to provide a metallization suitable for a Ni / Au plating process in a subsequent step for a ceramic wiring substrate having areas where the amount of exudation of the glass component is different.

On the surface of the ceramic (having no metallization), micro-cracks are generated by liquid honing, and metallized grains are mixed therein, or a Pd active solution or a plating solution is mixed in a later plating process. This causes plating to be deposited, but by masking, plating deposition on the ceramic can be reduced.

[0011]

Embodiments of the present invention will be described below.

[0012]

[Embodiment 1] To manufacture a ceramic substrate, a hole-filled green sheet is printed by embedding using a W paste, and a green sheet wired by a pattern printing method is laminated and bonded. Thereafter, sintering is performed at 1600 ° C. in a mixed atmosphere of N ₂ + H ₂ + steam. Here, W on the ceramic surface
The wiring pattern (hereinafter referred to as W sintered conductor) is fired at the same time, and the exudation of the glass component occurs on the surface thereof.
In addition, foreign substances such as ceramics are also adhered at the time of sintering, so that they are first removed in advance by polishing with a braided grindstone. FIG. 1 is a cross-sectional view of a ceramic substrate in which a glass component has exuded on a W sintered conductor. Further, when the amount of exudation of the glass component is compared in the same substrate, it can be divided for each area. Here, FIG. 2 shows a map diagram of the amount of exudation of the glass component. Here, x: indicates a portion with a large amount of glass, and ○: indicates a portion with a small amount of glass. Therefore, a mask shown in FIGS. 3 and 4 is prepared, and first, liquid honing is selectively performed on a portion having a large amount of glass using the mask A shown in FIG. When the amount of glass is large, 1-3 k
gf / cm ² . Next, the mask B shown in FIG.
, Liquid honing was selectively performed on a portion having a small amount of glass. In this case, the honing pressure is 1kg
f / cm ² or less. Thereafter, Ni / Au plating is performed after performing ultrasonic cleaning to remove abrasive grains of the honing. First, 30 ° C in 10 wt% caustic soda at 90 ° C.
After immersion for a minute and washing with water, Pd activation treatment (Nippon Kanigen, Activated No. 3 solution) is performed at 60 ° C. for 5 minutes to form Ni plating on the W sintered conductor. This is because the reaction of direct reduction Ni plating does not start on W. Then 1: 1
After immersing in a Hcl solution (RT, 3 minutes) to remove the Pd active catalyst on the ceramic, washing with water, and immersing in Ni plating solution (SB-55-1 manufactured by Nippon Kanigen) at 60 ° C. for 25 minutes, Ni Deposit about 3 μm of plating. After this,
Heat treatment is performed in a reducing atmosphere at 750 ° C. for 10 minutes to mutually diffuse the underlying W and the Ni plating film to improve the adhesion between the W and the Ni plating film. Furthermore, alkali degreasing (manufactured by EEJA,
After performing Eatrex, 60 ° C., 3 minutes) and 1: 1 Hcl treatment (RT, 1 minute), substitutional Au plating (EEJA)
Manufactured by Lectrores Prep, 90 ° C, 10 minutes)
About 0.05 μm of Au plating is applied. In addition, heat treatment in a reducing atmosphere at 350 ° C. for 30 minutes is performed in order to ensure adhesion between Au and the underlying Ni. FIG. 5 shows Ni / A on W sintered conductor.
FIG. 4 shows a cross-sectional view of a case where u plating is performed. With the ceramic substrate thus obtained, it is possible to obtain a ceramic wiring substrate free from plating non-precipitation and pattern loss due to swelling of the glass component on the W sintered conductor. FIG.
FIG. 2 shows a cross-sectional view of a state in which plating is not deposited and a pattern is lost due to excessive honing when the removal of the stain of the glass component is insufficient.

For comparison, liquid honing was performed without using a mask (honing pressure: 1 to 3 kgf /
cm ² ), Ni / Au plating was performed in the same manner as in Example 1. In the metallization at the center of the substrate, a pattern defect as shown in FIG. 6 was generated. Precipitation of Ni / Au plating (2 to 3 μm plating particles) also occurred. This can be presumed to be that the metallization at the center of the ceramic substrate has a small amount of seepage of the glass component, and under the honing condition in which the glass component at the outer periphery of the substrate can be removed, the metallization is too severe and the metallization is lost. It is also considered that micro-cracks were generated on the ceramic surface when the honing was strongly applied outside the metallized area, and plating was generated by mixing of the W particles and the Pd activating solution there.

[0014]

According to the present invention, the glass component can be removed without losing the metallization on the ceramic wiring substrate, and Ni /
An Au plating film can be formed, and the connection reliability of parts can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a ceramic substrate after sintering.

FIG. 2 is a map diagram of the amount of exudation on the metallized glass component.

FIG. 3 shows a mask A (glass amount: for many metallized areas).

FIG. 4 shows a mask B (glass amount: for a small metallized area).

FIG. 5 is a cross-sectional view of a ceramic substrate after Ni / Au plating.

FIG. 6 is a cross-sectional view of a ceramic substrate having no plating deposition and a pattern defect.

[Explanation of symbols]

1. Ceramic wiring board 2. W sintered conductor
3: Glass component exudation (foreign matter), 4: Glass amount: a large amount of W sintered conductor, 5: Glass amount: a small amount of W sintered conductor, 6
... Mask A, 7 ... Mask B, 8 ... Ni plating film,
9 ... Au plating film, 10 ... Plating non-precipitation due to exudation of glass components (foreign matter), 11 ... Pattern defect.

Claims (2)

[Claims] 1. A method for pre-plating a ceramic substrate having metallized wiring on its surface, wherein masking is performed in accordance with the amount of glass component exuding onto the metallized surface, and the glass component is removed by liquid honing. Plating pretreatment method. 2. A pre-plating method for a ceramic substrate having metallized wiring on its surface, wherein masking is performed on an area without metallization and liquid honing is performed.