JPS60193397A - Ceramic multilayer circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Technical field to which the invention pertains) The present invention relates to improvements in ceramic multilayer wiring boards.

(Prior art and its problems) In a conventional ceramic multilayer wiring board (hereinafter referred to as a wiring board), a #11 conductive layer is formed by coating a conductive paste mainly composed of KMo, W, etc. on a ceramic substrate. An insulating layer having a through hole is formed on the upper surface thereof and the through hole KAg.

It is generally known to form a second conductor layer by applying a noble metal paste such as Au.

However, the wiring board produced by the method described above has the disadvantage that the first conductor layer is easily oxidized because the second conductor layer is sintered in the atmosphere.

As a countermeasure to this problem, there is a method of firing in a neutral or reducing atmosphere, but this method requires the expense of creating a neutral or reducing atmosphere. In other words, the problem is that manufacturing costs are high.

(Object of the Invention) The object of the present invention is to provide a wiring board free from these drawbacks.

(Means for Solving the Problems)' As a result of various studies on the above-mentioned drawbacks, the present inventors found that a first conductor layer containing a high melting point metal as a main component and a second conductor layer consisting of Ag/Pd. It was confirmed that by forming an inert metal layer in the through hole between the insulating layers, the first conductor layer would not be oxidized even when fired in the atmosphere.

(Structure of the Invention) The present invention provides a first conductor layer containing a high melting point metal as a main component and an Ag
The present invention relates to a wiring board in which an inert metal layer is formed in a through hole between an insulating layer and a second conductor layer made of /Pd.

(Material Examples) In the present invention, Mo, W, etc. are used as high melting point metals, and noble metals with relatively high melting points such as Pi, Pd, Rh, etc. are used as inert metals. The inert metal layer is formed by methods such as electroless plating, electrolytic plating, and vapor deposition.

The first conductor layer in the board is a conductor layer formed inside the wiring board (near the ceramic substrate), and the second conductor layer is a conductor layer exposed on the surface.

The first conductor layer may have a single layer or a multilayer structure, and is not particularly limited. Further, in the present invention, another conductive metal layer may be formed between the first conductive layer and the inert metal layer.

(Example) The present invention will be explained below with reference to Examples.

Example 1 96% by weight of aluminium, 2.0% by weight of silica, 1.0% by weight of calcia and 1.0% by weight of magnesia
Next, 0 parts by weight of polyvinyl butyral as an organic binder was added to 10 parts by weight of the composition.

4.0 parts by weight of DOP as a plasticizer and 50 parts by weight of an azeotropic mixture of trichlorethylene and methyl alcohol were added to the organic solvent and mixed uniformly.

Then, a ceramic green sheet with a thickness of 0.8 mm was obtained by the Doc Turblade method.

On the other hand, apart from the above, W (
60% by weight of each powder (tungsten).

40% by weight was blended, and 30 parts by weight of organic material was added to 100 parts by weight of this W powder and mixed uniformly to obtain a W paste.

Next, the above-mentioned W paste was screen printed on the above-mentioned ceramic green sheet, and an insulating paste having the same composition as the above-mentioned ceramic green sheet was applied on the top surface with a diameter of 0.2 mm.
PH5O/P after printing leaving a mm through hole
200 for 1 hour in a weakly reducing atmosphere with Ht = 0.45
The temperature was raised to 1560'C at a temperature increase rate of 150°C.

Hold at 1560℃ for 1 hour and then bake at 300℃ for 1 hour.
A ceramic substrate on which a first conductor layer and an insulating layer were formed was obtained by decreasing the temperature at a rate of .

Next, after activating the above sintered ceramic substrate using the usual wet plating method, electroless Pt plating is applied to a thickness of 5 μm on the first conductor layer exposed through the through hole. , then washed and dried at 950°C in an H1 atmosphere.
Heat treatment was performed at ℃ for 20 minutes.

Furthermore, an Ag/Pd thick film paste (trade name: TR-4846, manufactured by Matsusei Corporation, Japan) was screen printed on the above-mentioned insulating layer and the Pt plating layer of the through holes, and it was heat-treated at 900°C for 10 minutes in the air. A second conductor layer was formed to obtain a wiring board.

Example 2 A wiring board was obtained using the same composition and the same steps as Example 1, except that the heat treatment in the atmosphere after Pt plating was not performed.

Example 3 A wiring board was obtained using the same composition and the same steps as Example 1, except that Ni plating was applied to a thickness of 3 μm before PT plating.

Next, when the wiring boards obtained in Examples 1.2 and 3 were observed, no oxidation of the first conductor layer was observed. This is thought to be due to the structure in which the inert metal layer adheres closely to the first conductor layer and acts as a shielding film so that oxygen does not come into direct contact with the first conductor.

(Effects of the Invention) The present invention provides a first conductor layer containing a high melting point metal as a main component and an Ag
This is because an inert metal is formed in the through hole between the insulating layer and the second conductor layer made of Pd.

Since the #Il conductor layer does not oxidize and the second conductor layer can be sintered in the atmosphere, an inexpensive wiring board can be obtained.

Continuation of page 1 0 shots Akira Kamiyama Mamoru Hitachi City Higashimachi 4th Institute

Claims (1)

[Claims] 1. The first conductor layer mainly composed of a high melting point metal and Ag, /
A ceramic multilayer wiring board in which an inert metal layer is formed in a through hole between an insulating layer and a second conductor layer made of Pd.