JPS61271895A - Making of ceramic wiring substrate - 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] The present invention relates to a method for manufacturing a ceramic wiring board used as an electronic base material.

[Background technology]

The conventional method for making circuit boards made from inorganic wiring boards such as ceramics is to draw a circuit on an alumina green ceramic sheet before firing using a conductive paste such as tungsten or molybdenum-manganese, and then fire the entire sheet in a reducing atmosphere. , or Ag/Pd, Ag/Pt, A
A method of forming a paste by mixing noble metal fine powder such as u with a glass frit organic vehicle, screen printing it on a fired ceramic substrate, and then firing it at a temperature that melts and bonds the glass frit to the ceramic substrate to form a circuit. is common. However, these methods generally have difficulty forming fine wiring, and the former method in particular is not suitable for fine wiring due to high wiring resistance, and the latter method uses precious metals, resulting in high costs. . There is also a method of using a paste of Cu powder instead of the above-mentioned noble metal, but in this method, since Cu reacts more easily than noble metals, it is necessary to precisely control the paste composition, firing conditions, etc., and it is not practical. Not. Furthermore, since it contains glass, it has disadvantages such as poor solder adhesion, a tendency to produce defective products, and a tendency to break down or break down during use.

A circuit is formed by bonding a ceramic substrate and copper foil using an adhesive, forming an etching resist film on a predetermined circuit part, etching away parts other than the predetermined circuit part, and then peeling off the etching resist film. There is a way. However, there is currently no good inorganic adhesive.
This method is generally not used because adhesives based on this method are inferior in properties such as heat resistance, chemical resistance, and dimensional stability.

Other methods for manufacturing the ceramic wiring board include a chemical plating method, and a vapor phase method such as vapor deposition, sputtering, or ion blasting. Since these methods do not have the above-mentioned drawbacks, they can be said to be highly practical.

However, it is difficult to obtain strong adhesion between the substrate and the metal layer.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing a ceramic wiring board having a circuit with low wiring resistance and high adhesion to the ceramic substrate.

[Disclosure of the invention]

In order to achieve the above object, the present invention provides a ceramic substrate with a base material containing a metal compound as a main component and, if necessary, a noble metal compound that serves as an activator of electroless plating and at least one of Cu and Ni. The gist of the method is to form a ceramic wiring board by attaching it to the surface, heating and baking it in a non-oxidizing atmosphere to form a base layer, and forming a circuit on the surface of the base layer by plating.

This invention will be explained in detail below.

The metal compounds used in this invention include the material of the circuit to be formed and, when the formation method is plating,
A metal compound that forms an appropriate base is selected depending on the type of plating solution. For example, if the circuit is Ag, Cu, N
When formed by electroless plating, the metal compounds include CuS, CuCO3, CuC
Powder of at least one copper compound among It, CuSO4, etc. is suitable. In the method for manufacturing a ceramic wiring board of the present invention, although the object of the invention can be achieved using the above-mentioned metal compound alone, a noble metal compound that serves as a binder and an activator for electroless plating is also used.

By adding at least one of Cu and Ni, the effects of the invention can be further enhanced. The binder either contains glass in advance or is made of powder of compounds such as silicates that form glass when fired, and serves to strengthen the bond between the metal compound and ceramic by firing. have. Furthermore, when mixed with a metal compound, these binders also function as an extender and a dispersant for the metal compound. Examples of the binder include kaolin and borosilicate glass, but it is also possible to use other compounds as the binder as long as they function as described above. Preferably, 5 to 50 parts of this binder is blended to 95 to 50 parts by weight (hereinafter referred to as "parts") of the metal compound. A noble metal compound that acts as an activator for electroless plating,
Both Cu and Ni are incorporated into the underlayer by being fired together with the metal compound and binder, and work together with the metal compound as an activator for plating. As the noble metal compound, any compound that is normally used as an activator for electroless plating can be used. For example, as a Pd compound, P
Typical examples of the Au compound include dC1, pd□, and AuC1. The amount of this noble metal compound is preferably 0.0 parts per 100 parts of the mixture of metal compound and binder. If necessary, Cu or Ni1, or both Cu and Ni, preferably 5 to 30 parts, are further blended to a mixture of 0 or more containing 1 to 1 part of O to prepare a base material. In the method for manufacturing a ceramic wiring board of the present invention, the prepared base material powder may be attached to the ceramic substrate as is, but an appropriate binder and its solvent, such as printing ink such as screen oil, balsam, etc. may be added. They can also be mixed and applied as a paste to a ceramic substrate. If the base material is made into a paste, it becomes possible to easily draw a circuit pattern using the base material on the ceramic substrate by attaching it to the ceramic substrate using a method such as screen printing. Of course, methods other than screen printing can be used to attach the base material to the ceramic substrate. Substrate materials include alumina, forsterite, steatite, zircon, and mullite.

Oxide-based sintered ceramics such as cordierite, zirconia, and titania are mainly used, but carbide-based and nitride-based ceramics can also be used.

The base material deposited on the ceramic substrate is heated and fired in a non-oxidizing atmosphere to form a base layer on the ceramic substrate.

The non-oxidizing atmosphere herein refers to an inert gas atmosphere (eg, N2 atmosphere) containing a trace amount of oxygen (preferably 2000 ppm or less), a reducing atmosphere, a vacuum, and the like. The firing temperature may be any temperature at which the base material melts, and its preferable range is limited depending on the material of the base material. For example, when the copper compound is used as a metal compound, the firing temperature is not particularly limited, but
Preferably, the temperature is within the range of 300°C. The base material is
By heating and firing in a non-oxidizing atmosphere, a part of the metal compound contained in the base material is reduced to metal, and the base material containing this metal is heated and melted, and a part of it becomes the ceramic base material. It penetrates into the interior and forms a strong bond between the underlayer and the ceramic substrate. As mentioned above, the underlayer formed on the ceramic substrate contains metals that are reduced and precipitated by firing in a non-oxidizing atmosphere,
Pre-blended Cu, Ni, and precious metals such as Au and PB, which are also reduced and precipitated, are dispersed.
The object of the present invention is achieved because these metals deposited near the surface of the underlayer act as an activator for plating.

A circuit is formed on the surface of the fired base layer by electrolytic or electroless plating.

When forming a metal layer, a sufficient effect can be obtained even if the substrate is plated immediately after firing, but the surface of the substrate after firing must be cleaned with acid etc.
It is possible to further improve the deposition properties of plating, the adhesion of the circuit to the substrate, etc.

Although the material of the circuit is not particularly limited, it is preferable to use Cu, Ag, Ni, etc., which are usually used for wiring boards, for the circuit, both from the viewpoint of cost and from the viewpoint that conventional technology can be used. As for the plating method, a method generally used when plating these metals can be used.

For example, when plating Cu, electroless plating using formalin as a reducing agent can be used. Also,
When plating Ni, for example, electroless plating can be performed using a nickel plating solution using sodium hypophosphite or a boron-based reducing agent, and other methods can also be used. As described above, by performing electrolytic plating or electroless plating, a circuit is formed on the circuit pattern drawn on the ceramic substrate using the base layer, and a ceramic wiring board is obtained.

As described above, in the method for manufacturing a ceramic wiring board of the present invention, the base layer adhered to the ceramic substrate and the ceramic substrate are fused to each other and firmly bonded, and the metal deposited on the surface of the base layer is It is also firmly connected to the circuit by plating, and as a result, it is possible to form a circuit with high adhesion to the ceramic substrate.

Since the circuit can be formed by ordinary plating, it is possible to select and use materials with low cost and high conductivity, making it possible to manufacture low-cost ceramic wiring boards with low wiring resistance. .

Next, embodiments of the invention will be described.

(Example 1) Copper sulfide (CuS) was used as a metal compound, and this Cu
25 parts of kaolin is added to 75 parts of S, and Ni
A paste base material was prepared by mixing 15 parts of PdCIzo and 02 parts of PdCIzo, and adding screen oil. 96
% alumina ceramic substrate by screen printing, and dried at 100° C. for 5 minutes. This ceramic substrate was placed in nitrogen (oxygen content 200p).
pm) at 1100° C. for 10 minutes to form a base layer. Prior to plating, this ceramic substrate was cleaned by immersing it in 5% hydrochloric acid at 50° C. for 1 minute, and was further washed with water for pretreatment. Thereafter, electroless plating was performed by immersing it in a copper plating solution at 25° C. for 60 minutes to form a copper layer serving as a circuit on the base layer to obtain a ceramic wiring board.

When we investigated the adhesion of the obtained ceramic wiring board, we found that
It showed very high adhesion of 2.5 to 3.0 kg/lIIm, and when the resistance was measured, it was 2mΩ/1
aaI", a very small value.

(Example 2) Using copper carbonate (CuCOz) as a metal compound,
For this CuC0,3Q part, 20% of borosilicate glass is added.
part Cu2O and PacttQ,03
A paste-like base material was prepared by mixing the two parts and adding screen oil. On a 96% alumina ceramic substrate,
This base material was attached by screen printing, and 100
Drying was performed at ℃ for 5 minutes. This ceramic substrate was heated and baked at 1050° C. for 10 minutes in nitrogen (M content: 150 ppm) to form a base layer. Prior to plating, this ceramic substrate was cleaned by immersing it in 5% hydrochloric acid at 50° C. for 1 minute, and was further washed with water for pretreatment. after this,
Electroless plating was performed by immersing it in a copper plating solution at 25° C. for 60 minutes to form a copper layer serving as a circuit on the base layer to obtain a ceramic wiring board.

When we investigated the adhesion of the obtained ceramic wiring board, we found that
2.0 to 2.5 kg/n's" showed very high adhesion, and when the resistance was measured, it was 2II1Ω.
/mm”, a very small value.

(Example 3) A ceramic wiring board was prepared in the same manner as in Example 1 except that 75 parts of copper chloride (CuC1□) was used as a metal compound and a part of Cu2O was added thereto. Adhesion of the obtained ceramic wiring board I checked the power.

However, it showed very high adhesion of 2.0 to 2.5 kg/IIImz, and when the resistance value was measured, it was 2.
mΩ/III! showed a very small value.

(Example 4) 80 parts of copper chloride (CuCIz) was used as a metal compound, 20 parts of borosilicate glass was added to this, and 9 parts were used as a substrate.
Example 1 except that a 2% alumina ceramic substrate was used.
A ceramic wiring board was created in the same manner as above.

When we investigated the adhesion of the obtained ceramic wiring board, we found that
It showed very high adhesion of 2.0 to 2.5 kg/mm, and when the resistance was measured, it was 2mΩ/III.
It showed a very small value of Im''.

(Example 5) 75 parts of copper sulfate (CuSOa) was used as a metal compound, and 25 parts of kaolin, CulS part, pd
3 parts of cizo and o were added, a 92% alumina ceramic substrate was used as the substrate, and the oxygen content of the nitrogen atmosphere was 150%.
A ceramic wiring board was produced in the same manner as in the example except that the concentration was ppm.

When we investigated the adhesion of the obtained ceramic wiring board, we found that
It exhibited very high adhesion of 2.0 to 2.5 kg/mm, and when the resistance was measured, it was 21IIΩ/n.
It showed a very small value of III+2.

〔Effect of the invention〕

The method for manufacturing a ceramic wiring board of the present invention is configured as described above, and since the ceramic board and the circuit are connected through the base layer that tightly adheres to each other, it is possible to create a circuit with high adhesion. Because it can be formed and normal plating can be used, wiring resistance can be reduced.
Moreover, costs can be reduced.

Claims (6)

[Claims] (1) The main component is a metal compound, and if necessary, a noble metal compound that serves as an activator for electroless plating, as well as Cu and Ni.
A ceramic in which a base material containing at least one of the following is adhered to the surface of a ceramic substrate, heated and fired in a non-oxidizing atmosphere to form a base layer, and a circuit is formed on the surface of this base layer by plating. Manufacturing method for wiring boards. (2) Metal compounds are CuS, CuCO_3, CuCl_
2. The method for manufacturing a ceramic wiring board according to claim 1, wherein the copper compound is at least one copper compound selected from the group consisting of CuSO_4 and CuSO_4. (3) The method for manufacturing a ceramic wiring board according to claim 1 or 2, wherein the base material also contains a binder, and the binder is one of kaolin and borosilicate glass. (4) The method for manufacturing a ceramic wiring board according to any one of claims 1 to 3, wherein the noble metal compound is palladium chloride. (5) The method for manufacturing a ceramic wiring board according to any one of claims 1 to 4, wherein the oxygen content of the non-oxidizing atmosphere is 2000 ppm or less. (6) The method for manufacturing a ceramic wiring board according to any one of claims 1 to 5, wherein the heating and firing temperature is 900 to 1300°C.