JPH02150097A - Manufacture of ceramic multilayer wiring board - Google Patents

Abstract

PURPOSE:To easily form a microscopic circuit by plating with nickel-phosphorus and copper the exposed face of an inner conductor layer of alumina ceramic, heat treating it, and then roughing the surface, and further forming a conductor circuit on the surface. CONSTITUTION:An inner conductor layer is formed in alumina ceramic by partly exposing it on the surface by a green method. Then, the exposed face of the layer is successively plated with nickel-phosphorus(Ni-P) and copper(Cu), heat-treated in a weakly reducing atmosphere, the surface of the alumina ceramics is roughed, and a conductor circuit is further formed on the alumina ceramics. The material for forming the layer includes high melting point metal such as tungsten, molybdenum, molybdenum-manganese, etc., and the material for forming the circuit includes, for example, noble metal such as gold, silver, platinum, etc., or base metal such as nickel, copper, etc. The formation of the circuit includes, for example, a plating method, a vacuum depositing method, a sputtering method, etc., and it is desirable to form the circuit by an electroless plating method. The heat treatment is required to be conducted in the weak reducing atmosphere.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing a ceramic multilayer wiring board.

In particular, the present invention relates to a method of manufacturing a ceramic multilayer wiring board in which a conductor circuit is formed on the surface layer.

(Prior art) A conventional ceramic multilayer wiring board has an internal conductor layer mainly composed of high melting point metal powder such as tungsten, molybdenum, molybdenum-manganese, etc., formed in alumina ceramics.
A part of the internal conductor layer is brought out to the surface through a through hole, and a noble metal paste such as gold, silver, platinum, etc., or a base metal paste such as nickel, copper, etc. is applied to the exposed surface of the internal conductor layer exposed above the through hole. It is generally known that a conductive circuit is formed by a printing method and then fired in a weakly reducing atmosphere.

(Problem to be Solved by the Invention) However, with the method described above, it is very difficult to form a fine circuit (fine line).

Furthermore, the paste material forming the noble metal layer, base metal layer, etc. must contain a glass component in order to improve the adhesive strength of the conductor circuit. Therefore, there is a drawback that the conduction resistance with the internal conductor layer is high and the reliability is poor.

The object of the present invention is to provide a method for manufacturing a ceramic multilayer wiring board that does not have the above-mentioned drawbacks.

(Means for Solving the Problems) The present invention involves forming an internal conductor layer in alumina ceramics by exposing a portion to the surface using the green method, and then coating the exposed surface of the internal conductor layer with nickel-phosphorus (Ni, P). The present invention also relates to a method for manufacturing a ceramic multilayer wiring board, in which the surface of alumina ceramics is roughened after copper (Cu) plating and heat treatment in a slightly reducing atmosphere of 2, and conductor circuits are formed on the surface of the alumina ceramics.

In the present invention, high-melting point metal powders such as tungsten, molybdenum, and molybdenum-manganese are used as materials for forming the internal conductor layer, and noble metals such as gold, silver, and platinum, and nickel are used as materials for forming the conductor circuit. , base metals such as copper are used.

The conductor circuit can be formed by methods such as plating, vacuum evaporation, and sputtering.9 In the present invention, it is preferable to form the conductor circuit by electroless plating.

The heat treatment must be performed in a weakly reducing atmosphere, and heat treatment in an oxygen atmosphere has the disadvantage that the internal conductor layer is oxidized.

There are no particular restrictions on the method for roughening the surface of the alumina ceramics, and any conventionally known method may be used.

(Example) The present invention will be explained in detail below.

Example 1 Alumina ceramic green sheet with a thickness of 0.8 m (
Cut two sheets of alumina (purity 96% by weight) (hereinafter referred to as green sheets) into a size of 50 x 50nnu, and make a hole (through hole) with a diameter of 0.31 [1llI] in one of the sheets.
Then, the through holes were filled with tungsten paste (manufactured by Asahi Chemical Co., Ltd., trade name 3TW-1200), and the same tungsten paste as described above was printed on one surface by screen printing and dried. After drying, the green sheet with the tungsten paste filled in the through holes was placed on top of the green sheet with the tungsten paste printed side down, and heated at 100°C.

Heat and pressurize under the conditions of 6 kg/am", then heat in an electric furnace for 5
Heated in air to 300°C at a heating rate of 0°C/hour, then further heated to 1600°C at a heating rate of 30°C/hour in a slightly reducing (N2) atmosphere, and held for 1 hour. A ceramic wiring board was obtained by sintering the green sheet and sintering the tungsten paste so that a portion of the green sheet was exposed on the surface to form an internal conductor layer in alumina ceramics.

Next, the ceramic wiring board obtained above was degreased in a degreasing bath containing sodium hydroxide (manufactured by Nippon Electroplating Engineers Co., Ltd., trade name: Eedrex Nα12), and then in an activated bath (manufactured by World Metal Co., Ltd., Product name A
Pd was added using T-80), and electroless N1-P plating (manufactured by Nippon Kanigen Co., Ltd., trade name 8680) was performed, followed by washing with water and drying to form a 2 μm thick N1-P plating layer.
Further, electrolytic copper plating (trade name: Curex EF, manufactured by Nippon Playteng Engineers Co., Ltd.) was performed on this plating film, followed by washing with water and drying to form a copper plating layer with a thickness of 3 μm.

Thereafter, heat treatment was performed at a temperature of 800° C. for 10 minutes in a weakly reducing atmosphere, and then roughening treatment was performed for 10 minutes with an alkali molten salt at 350° C. Further, as Pd addition, catalyst treatment (manufactured by Hitachi Chemical Co., Ltd., trade name H8-101B) and accelerator treatment (manufactured by Hitachi Chemical Co., Ltd., trade name ADP-30)
1) After that, electroless copper plating (manufactured by Hitachi Chemical Co., Ltd., product name L)
-59) to form a copper plating layer with a thickness of 7 μm. Photosensitive resist film after plating (manufactured by Hitachi Chemical Co., Ltd., trade name: Photograph PHT-862AF-25)
was pasted on the entire surface of the copper plating layer, and a negative film with a transparent part formed in the same shape as the conductor circuit to be obtained was pasted on the top surface, and 80 mJ / Cr1? The image was exposed under the following conditions and developed with a 2% sodium carbonate solution.

Next, remove the negative film, remove the photosensitive resist film in the undeveloped areas, more specifically, the unexposed areas, and etching with ammonium persulfate solution at a concentration of 25% to remove copper plating in areas unnecessary for conductor circuits. layer removed. Thereafter, the photosensitive resist film was peeled off using a sodium hydroxide solution having a concentration of 5%, to obtain a ceramic multilayer wiring board on which conductor circuits were formed.

Example 2 A ceramic wiring board was obtained in the same manner as in Example 1, except that molybdenum-manganese paste (compounded in-house) was used in place of the tungsten paste used in Example 1.

After that, in the same manner as in Example 1, degreasing treatment, Pd addition, and N
1-P plating, copper plating and roughening treatment were performed.

Next, a sensitizer treatment (manufactured by World Metal Co., Ltd., trade name MC-8) was performed, and further, after Pd was applied, an activator treatment (manufactured by World Metal Co., Ltd., trade name MC-A) was performed.
N1-B plating (manufactured by World Metal Co., Ltd., trade name: diboron) was performed to form an N1-B plating layer with a thickness of 5 μm, followed by heat treatment at a temperature of 450° C. for 10 minutes. Thereafter, a photosensitive resist film was attached, a negative film was attached, exposed and developed in the same manner as in Example 1, and then etched with an etching agent (manufactured by Kizai Co., Ltd., trade name: Cera etching agent) to form a conductive circuit. The necessary portions of the Ni B plating layer were removed. Thereafter, a ceramic multilayer wiring board was obtained in the same manner as in Example 1.

Comparative Example 1 Copper paste (
Ceramic multilayer manufactured by DuPont, product name 9924Q) was printed using a screen printing method, dried at a temperature of 100°C for 10 minutes, and then heat-treated at a temperature of 800°C for 10 minutes in a slightly reducing atmosphere to form a conductor circuit. Get the wiring board.

The conduction resistance with the conductor layer and the appearance were observed.

As a result, the ceramic multilayer wiring boards obtained in each example are as follows.

No change was observed in the oxidation of the internal conductor layer or in the four-way resistance.

No abnormality was observed in the conductor circuit. On the other hand, in the ceramic multilayer wiring board obtained in Comparative Example 1, the internal conductor layer was oxidized, the conduction resistance became high, and blisters occurred in some places in the conductor circuit.

(Effects of the Invention) According to the present invention, a fine circuit can be easily formed,
Since the internal conductor layer and the like are not oxidized and the disadvantage of high conduction resistance with the internal conductor layer does not occur, it is possible to obtain a ceramic multilayer wiring board with excellent reliability.

Claims (1)

[Claims] 1. An internal conductor layer is formed in the alumina ceramic by exposing a part to the surface using the green method, then nickel-phosphorus and copper plating is applied to the exposed surface of the internal conductor layer, and after heat treatment in a weakly reducing atmosphere, the alumina ceramic A method for manufacturing a ceramic multilayer wiring board characterized by roughening the surface of the ceramic and further forming a conductor circuit on the surface of the alumina ceramic.