JPH03205892A - Ceramic printed wiring board and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a ceramic printed wiring board having high accuracy and a high characteristic by making a catalytic metal for precipitating electroless plating exist also on a ceramic board under a thin film resistor layer. CONSTITUTION:A ceramic board is dipped into a molten caustic soda to properly roughen the ceramic board surface so as to perform trial catalysis of electroless copper plating all over the ceramic board. After drying the ceramic board by a warm current, thin film conductor sintering paste is applied by a screen printing method and after being dried air sintering is performed so as to form a thin film conductor terminal layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a ceramic printed wiring board having high precision and high characteristics.

(Prior Art) Efforts have already been made to combine a thick film resistor layer and a plated conductor circuit in a ceramic printed wiring board using wet plating.

The manufacturing method can be roughly divided into two types: one is to arrange a thick film resistor layer and a resistor protective layer on a ceramic substrate with holes as necessary, and use only electroless plating, or electroless plating. After forming a metal layer of the desired thickness on the ceramic substrate including the inner wall of the hole using a combination of electroplating and electroplating, an etching resist film is formed on the desired part, and the metal part other than the desired part is removed by etching. This manufacturing method is called the subtractive method, which is a manufacturing method for forming circuit patterns. Another method is to arrange a thick film resistor layer and a resistor protective layer on a ceramic substrate with holes as needed, and then apply a metal layer on the ceramic substrate, including the inner walls of the holes, by electroless plating. After the formation, a plating resist film is formed on areas other than the desired areas, electroplating is further performed to a desired thickness, and after the plating resist is removed, the metal layer is etched away on areas other than the desired areas, thereby obtaining a circuit pattern. This is a method called a semi-additive method.

In both the subtractive method and the semi-additive method described above, since the catalyst is applied after forming the thick film resistor layer and the resistor protective layer, a metal film is also formed on the resistor protective layer, which is originally an unnecessary part. Ru. Although the unnecessary plated metal film has extremely weak adhesion to the resistor protection layer, it can be removed in a later etching process, but it causes many problems in the process until it is removed. For example, during electroless plating, the plating metal film on the resistor protective layer peels off and floats in the plating solution, causing deterioration of the plating solution. Alternatively, a plating solution or other processing solution may enter between the resistor protective film and the plated metal film thereon, and this solution may ooze out in a later process, contaminating or corroding the surrounding circuitry. Furthermore, if a strong plating film with a hemispherical bulge is formed on the resistor protection glass, it will have a significant adverse effect on the pattern accuracy of the plating resist or the etching resist.

(Problems to be Solved by the Invention) The present inventors have conducted intensive research to solve the problems of the conventional technology in a method for manufacturing a ceramic printed wiring board with high precision and high characteristics, and as a result, discovered the present manufacturing method. Ta.

(Means for Solving the Problems) That is, the present invention provides a method in which a thick film conductor layer, a thick film resistor layer, and a resistor protection layer for protecting the thick film resistor layer are arranged on a ceramic substrate, and , a ceramic printed wiring board having a conductor circuit formed by wet plating, characterized in that a catalyst metal for depositing electroless plating is also present on the ceramic substrate under the thick film resistor layer. A ceramic wiring board, characterized in that in the ceramic printed wiring board, a catalyst for depositing electroless plating on the ceramic substrate is applied before forming a thick film resistor layer and a resistor protective layer.・It is a method for manufacturing printed wiring boards.

The ceramic substrate in the present invention refers to an alumina-based substrate,
These are aluminum nitride substrate and silicon carbide substrate. Also,
Although the ceramic substrate can be used as is, it is preferable to use a ceramic substrate whose surface has been mechanically and/or chemically roughened in order to increase the adhesion of the plated conductor circuit. preferable.

These ceramic substrates may have through holes formed therein if necessary.

The thick film conductor layer in the present invention refers to a layer made of conductive fine powder of silver, silver/palladium, gold, copper, nickel, etc., an organic vehicle, a metal vehicle, a metal oxide, and/or a glass frit. It is made by firing the steel under appropriate conditions.

The thick film resistor layer in the present invention includes, for example, conductive fine powder of silver, palladium, ruthenium compound, tantalum, tin, indium oxide, lanthanum boride, carbon, etc.
A paste composed of a glass frit, a metal oxide, and an organic vehicle, or a resin composition in which the conductive fine powder is blended with a resin such as phenol, epoxy, or polyimide, and is fired or hardened under appropriate conditions. It is.

The resistor protective layer in the present invention is an insulating layer with chemical resistance formed on a thick film resistor, such as a paste composed of a glassy frit, a metal acid compound, and an organic vehicle, or an epoxy resin. , phenol, polyimide, etc., and is fired or hardened under appropriate conditions.

Electroless plating in the present invention refers to electroless plating of tin, nickel, copper, silver, gold, platinum, luteium, and cobalt.

Catalyzing in the present invention means adsorbing a catalytic metal for electroless plating onto the ceramic surface, and the catalytic solution is preferably a known palladium compound solution, but it may also be a solution of copper, platinum, gold, or other metal compounds. A solution may be used. This catalytic metal is oxidized when forming the thick film resistor layer and may lose its catalytic ability, so a reduction treatment is performed before electroless plating. This reduction method can be used, for example, for 15
There are a method of heat treatment at 0° C. and a method of immersion in a reducing agent solution, but these are not particularly limited.

(Example) Examples will be given to explain the present invention in more detail.
The present invention is not limited in any way by these Examples.

Example-1〉 Containing 96% alumina with through holes arranged at desired locations, length 50.8 m + a, width 50.8 m - thickness 0.835
A +o+a white ceramic substrate was immersed in molten caustic soda maintained at 340° C. for 10 minutes to appropriately roughen the surface of the ceramic substrate. Next, a catalyst was applied to the entire surface of the ceramic substrate for electroless copper plating. The catalyst application process used PTH process 4 [manufactured by Shipley Far East ■]. After drying the above ceramic substrate with hot air, a thick film conductor firing paste was applied by screen printing method,
It was dried at 150° C. for 10 minutes and air fired at 900° C. for 10 minutes (35 minutes in total) to form a thick film conductor terminal layer. The spacing between thick film conductor terminal layers is 1. It was set to 0U. Next, thick film resistor firing paste (R9310N) [manufactured by Shoei Kagaku Kogyo Co., Ltd.] was applied by screen printing so that both thick film conductor terminal layers were partially overlapped, and heated at 150°C for 10 minutes.
Dry for 10 minutes at 850℃ (total 35 minutes)
Air fired. Furthermore, in order to protect the thick film resistor, a thick film resistor protective layer (glass paste for overcoat G#5238) [Shoei Chemical Co., Ltd.] was applied so as to cover the entire surface of the thick film resistor layer.
Coating material was applied by screen printing method and heated at 150℃ for 10 minutes.
Dry for 1 minute, then at 600℃ for 10 minutes (total 3 minutes).
5 minutes) in air. Next, attach the above ceramic substrate to 9
After being immersed in 0% formic acid for 5 minutes, it was dried at 150° C. for 10 minutes and immersed in an electroless copper plating bath to obtain a copper plating film of about 1.0 μm on the ceramic substrate. As the electroless copper plating bath, Cuposit 250 bath [manufactured by Shipley Far East ■] was used. At this time, no copper plating film was formed on the thick film resistor protective layer. Furthermore, the negative resist was coated with photosensitive dry film AP838 [
Tokyo Ohka Kogyo 1N] was used to deposit electrolytic copper plating in a thickness of about 10 μm on the desired portions. After that, the chemical steel plated part was coated with 0.1M-H2 02 /O.
It was removed using an IM.H2SO4 etching solution, and the circuit shown in FIG. 1 was formed. By this method, a fine pattern with a line space of 50 μm could be obtained. The defective rate was 0% (n=100).

<Example 2> A catalyst for electroless copper plating was deposited on the entire surface of a ceramic substrate that had been appropriately roughened using the same method as shown in Example 1. The catalyst application process used the activator system Neogant [Nippon Schering Co., Ltd.]. After drying the substrate with warm air, a thick film conductor terminal layer, a thick film resistor layer, and a thick film resistor protective layer were formed in the same manner as in Example 1, and a catalytic metal reduction treatment was performed. Next, the ceramic substrate was immersed in an electroless plating bath to obtain a copper plating film of about 10 μm on the ceramic substrate. As the electroless plating bath, KC-10 bath [manufactured by Nippon Mining Co., Ltd.] was used. At this time, no copper plating film was deposited on the thick film resistor protective layer. Furthermore, the positive etching resist was coated with a photosensitive dry film [AP 8
3 8 Tokyo Ohka Kogyo Co., Ltd.
The non-circuit portions were removed using an etchant of H 2 O 2 /IM·H 2 SO 4 and the resist was peeled off. By this method, a fine pattern with a line spacing of 50 μm was obtained. The defective rate was 0% (n=100).

<Example 3> A thick film conductor terminal layer was formed in the same manner as in Example 1 on a ceramic substrate that had been appropriately roughened in the same manner as in Example 1. Next, a catalyst for electroless copper plating was deposited on the entire surface of the substrate. The catalyst application process used the activator system Neogant [Nippon Schering Co., Ltd.].

After drying the substrate with warm air, a thick film resistor and a thick film resistor protective layer were formed in the same manner as in Example 1, and a catalytic metal reduction treatment was performed. Next, the ceramic substrate was immersed in an electroless plating bath to obtain a copper plating film of about 10 μm on the ceramic substrate. The electroless plating bath used was KC-10 bath [manufactured by Nippon Mining Co., Ltd.].

At this time, no copper plating film was deposited on the thick film resistor protective layer. Furthermore, a positive etching resist was coated with a photosensitive dry film [AP838 manufactured by Tokyo Ohka Kogyo Banriki].
1M-H202 /IM-H2So4
The non-circuit parts were removed using an etching solution, and the resist was peeled off. By this method, a fine pattern with a line spacing of 50 μm was obtained. The defective rate was 0% (n
= 1 00).

<Comparative Example-1> After forming a thick-film resistor layer, a thick-film conductor terminal layer, and a thick-film resistor protective layer on a suitably roughened ceramic substrate using the same method as shown in Example-1, the above ceramic A catalyst for electroless copper plating was applied to the entire surface of the substrate, and then electroless copper plating was performed.

For the catalyst application process, the activator system Neogant (manufactured by Nippon Schering Co., Ltd.) was used, and the electroless copper plating bath was Cuposito 250 bath (manufactured by Shipley Far East Co., Ltd.). At this time, a portion of the plating film on the thick film resistor protective layer was peeled off from the thick film resistor protective layer and floated in the plating layer.

Furthermore, after electroless plating, significant discoloration was observed in the copper plating film around the thick film resistor layer. Next, a circuit was formed in the same manner as in Example-1. By this method, 50 μm
A conductor short-circuit failure occurred in the line space fine pattern. The defect rate was 80% (n=100).

Comparative Example-2> After forming a thick-film resistor layer, a thick-film conductor terminal layer, and a thick-film resistor protective layer on a suitably roughened ceramic substrate using the same method as in Example-1, the ceramic substrate was A catalyst for electroless plating was applied to the entire surface, and then electroless copper plating was performed to obtain a copper plating film of about 10 μm. The catalyst application process used the activator system Neogant [Nippon Schering Co., Ltd., and the electroless plating bath was KC-10.
Bath [made by Nippon Mining Co., Ltd.] was used. At this time, a blistering defect occurred in the copper plating film on the thick film resistor protective film.

Next, a circuit was formed in the same manner as in Example-2. This method resulted in conductor loss defects. The defective rate was 76% (n=100).

(Effects of the Invention) By carrying out the present invention, it is possible to prevent the formation of a plating film with poor adhesion on the thick film resistor protective film, thereby solving the problems caused by this.

Therefore, it is extremely useful as a method for manufacturing ceramic printed wiring boards with high precision and high reliability.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view of a pattern used for evaluation of Examples 1 and 2 and Comparative Examples 1 and 2. 1. Plated conductor 50μm line space 2 Thick film resistor layer and resistor protection layer 3. conductor terminal layer

Claims (2)

[Claims] (1) A thick film conductor layer, a thick film resistor layer, and a resistor protection layer for protecting the thick film resistor layer are arranged on a ceramic substrate, and a conductor circuit by wet plating is arranged. 1. A ceramic printed wiring board characterized in that a catalyst metal for depositing electroless plating is also present on the ceramic substrate under the thick film resistor layer. (2) Claim 1. A method for manufacturing a ceramic printed wiring board, characterized in that a catalyst for depositing electroless plating on a ceramic substrate is applied before forming a thick film resistor layer and a resistor protective layer. Method of manufacturing the board.