JPH06177499A - Ceramic wiring board - Google Patents

Abstract

PURPOSE:To provide a ceramic wiring board, in which the adhesive properties of a conductor and a conductive path are not deteriorated even at the time of heating at a high temperature and reliability on the connection of the conductor and the conductive path is improved. CONSTITUTION:Conductors 2 composed of conductor paste containing silver are formed on the surface of a ceramic board 1, a resistor 3 is shaped while being brought into contact with the conductors 2, and nickel layers 5 held by said conductors 2 and conductive paths 6 are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic wiring board used as a printed wiring board.

[0002]

2. Description of the Related Art As a ceramic wiring board, Japanese Patent Publication No. 53-
21109, Japanese Patent Laid-Open No. 3-109793, etc., a conductor, resistor, and protective glass containing Ag as a component are sequentially printed on the surface of a fired ceramic substrate by a thick film method, and after firing, there is no A method is known in which a copper film is formed by an electrolytic copper plating method, and a predetermined conductive path is formed on the copper film by etching. In recent years, this ceramic wiring board is required to have heat resistance at high temperatures. Therefore,
For example, if the ceramic wiring board has a high temperature of 700 ° C. or higher,
Alternatively, when evaluated by a heat resistance test in which the conductor and the conductive path are left to stand at 250 ° C. for 1000 hours or more, there is a drawback that the adhesiveness between the conductor and the conductive path is reduced and the connection reliability between the conductor and the conductive path is reduced.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to bond a conductor and a conductive path in a ceramic wiring board even when heated to a high temperature. It is intended to provide a ceramic wiring board in which the connection reliability between the conductor and the conductive path is excellent without lowering the contact resistance.

[0004]

A ceramic wiring board according to the present invention has a conductor (2) made of a conductor paste containing silver on the surface of a ceramic substrate (1), and is in contact with the conductor (2). In the ceramic wiring board in which the conductive path (6) and the resistor (3) are formed, the nickel layer (5) sandwiched between the conductor (2) and the conductive path (6) is formed. Characterize.

[0005]

In the present invention, silver contained in the cured product of the paste constituting the conductor (2) is less likely to diffuse into nickel, whereas silver is more diffused into copper. Conventional 70
When heat-treated at 0 ° C. or higher or left at 250 ° C. for 1000 hours or longer, the silver in the conductor (2), which was present as a nucleus for adhesion with the conductive path (6), was transferred to the copper conductive path (6). It is presumed that, because of the diffusion, the adhesive force between the conductive path (6) and the conductor (2) is weakened and the connection reliability is reduced. Therefore, by sandwiching the nickel layer between the conductive path (6) and the conductor (2), the diffusion of silver in the conductor (2) is reduced, and a decrease in connection reliability can be prevented.

The present invention will be described in detail below. FIG. 1 is a sectional view showing an embodiment of a ceramic wiring board according to the present invention. As shown in the figure, the ceramic substrate (1) has a conductor (2) on its surface, and a resistor coated with a protective glass (4) in contact with a part of the conductor (2) and the ceramic substrate (1). (3) is formed. The conductor (2) not in contact with the resistor (3) is covered with the nickel layer (5), and the copper conductive path (formed on the ceramic substrate (1) with the nickel layer (5) interposed therebetween ( 6) and the conductor (2) are connected.

The above-mentioned ceramic substrate (1) is preferably of a sintered ceramic type, and the material thereof is, for example, alumina, forsterite, zirconia, mullite, cordierite, titania, barium titanate, calcium titanate or the like. The oxide-based ceramics are used mainly, but carbide-based ceramics such as silicon carbide and nitride-based ceramics such as aluminum nitride may be used, or a plurality of types of ceramics may be used in combination.

The ceramic substrate (1) is preferably subjected to a roughening treatment in advance in order to enhance the adhesion of the conductor (2) and the conductive path (6) on the surface. As the roughening treatment, for example, 2-1 in phosphoric acid at 250 ° C to 330 ° C is used.
A chemical surface-roughening treatment in which it is immersed for about 0 minutes can be used.

The conductor (2) is formed by a so-called thick film method using a conductor paste containing Ag. For this conductor (2), various known thick film methods may be used.
It is formed by screen-printing and baking a conductive paste containing g, a mixture of Ag and Pd as a component.
Ag contained in this cured paste serves as a nucleus for adhesion with nickel during nickel plating described later. The conductive paste functions to enhance the connection reliability with the resistor (3) even in the later-described thin conductive path (6).

A resistor (3) is formed on the ceramic substrate (1) on which the conductor (2) is formed. The resistor (3) may be formed by various known methods, for example, R
Print a resistor paste such as uO ₂ to 850-900
It is formed by firing at ℃.

A protective glass (4) is coated on the resistor (3). The protective glass (4) is formed, for example, by printing a glass paste on the ceramic substrate (1) on which the resistor (3) is formed and firing at 700 to 800 ° C. This glass paste is preferably one having excellent chemical resistance capable of withstanding a chemical treatment in a later step.

In the present invention, the portion of the conductor (2) not in contact with the resistor (3) is covered with the nickel layer (5). It is desirable that the nickel layer (5) is coated only on the conductor (2). As a coating method, for example, the conductor (2) is washed with hydrochloric acid, a commercially available nucleating solution or the like to activate it. After that, the exposed conductor (2) is covered with the electroless nickel plating solution by 2-3 μm.
A nickel layer (5) is formed.

A copper conductive path (6) is formed on a ceramic substrate (1) obtained by coating the conductor (2) with a nickel layer (5). The formation of the conductive path (6) is not particularly limited, and a known electroless copper plating method or high-speed sputtering method can be used. For example, when the conductive path (6) formed by electroless copper plating is used, Pd or the like is nucleated in a pretreatment, and the ceramic substrate (1) is immersed in an electroless copper plating bath to coat a copper film. The conductive path (6) can be formed by subjecting the copper coating to etching treatment using, for example, the photolinography technique. The conductive path (6) has a thickness of, for example, 3 μm when a high-density circuit is formed.
m to 20 μm is preferable.

[0014]

EXAMPLES Example 1 An alumina substrate was used as the ceramic substrate (1), and
The above ceramic substrate (1) after being immersed in phosphoric acid at 0 ° C for 4 minutes
The surface of was roughened. On the surface of the roughened ceramic substrate (1), a conductor paste in which Ag and Pd as components were dispersed in a glass paste was screen-printed and then baked to form a conductor (2). Next, a ruthenium oxide-based resistor paste was screen-printed and baked at 850 ° C. to form a resistor (3). Then, a glass paste having good chemical resistance was screen-printed and baked at 700 ° C. to cover the protective glass (4) on the resistor (3). Then 1
After washing and activating the conductor (2) with 0 vol% hydrochloric acid,
It was dipped in an electroless nickel plating solution to coat the exposed conductor (2) with a nickel layer (5) having a thickness of 3 μm. Then, as a pretreatment for electroless copper plating, P is applied to the ceramic wiring board (1) by the sensitizing activation method.
n is dipped and immersed in an electroless copper plating bath to a thickness of 1
A ceramic wiring board was obtained by forming a conductive path (6) on the copper film by covering with a 0 μm copper film and performing an etching treatment.

Example 2 An alumina substrate was used as the ceramic substrate (1). The conductor (2), the resistor (3) and the protective glass (4) were formed in the same manner as in Example 1 without performing the roughening treatment.
Next, the exposed conductor (2) is activated by immersing it in IPC Axela (trademark, manufactured by Okuno Chemical Industries Co., Ltd.), and then immersing in an electroless nickel plating solution to form a nickel layer (5) having a thickness of 2 μm. Was coated on the exposed conductor (2). afterwards,
The non-conductive path was masked with a metal mask, and the conductive path (6) was formed by high-speed sputtering to obtain a ceramic wiring board.

Comparative Example 1 Using an alumina substrate as a ceramic substrate, roughening treatment was performed in the same manner as in Example 1 to form a conductor, a resistor and a protective glass. Next, in the same manner as in Example 1, electroconductive paths were formed by electroless copper plating and etching.

The adhesiveness of the ceramic wiring boards of Examples 1 and 2 and Comparative Example 1 was evaluated. The adhesion test was conducted by heating the above-mentioned ceramic wiring board at 700 ° C. for 10 minutes, applying a tape to the conductive path (6) on the conductor (2), and peeling off the tape to remove the conductive path (6). It was measured with and without peeling. As shown in Table 1, the results of measuring 100 test pieces were 0 in Example 1 and 1 in Example 2, but 23 in Comparative Example 1 were peeled.

[0018]

[Table 1]

[0019]

According to the ceramic wiring board of the present invention, the adhesiveness between the conductor (2) and the conductive path (6) does not deteriorate even when heated to a high temperature, and the conductor (2) and the conductive path (6) do not deteriorate. Good connection reliability.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a ceramic wiring board according to the present invention.

[Explanation of symbols]

 1 Ceramic Substrate 2 Conductor 3 Resistor 4 Protective Glass 5 Nickel Layer 6 Conductive Path

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazunobu Morioka 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (1)

[Claims] 1. A ceramic substrate (1) has a conductor (2) made of a conductor paste containing silver on the surface thereof, and a copper conductive path (6) and a resistor (3) in contact with the conductor (2). In a ceramic wiring board in which is formed a nickel layer (5) sandwiched between the conductor (2) and the conductive path (6).
A ceramic wiring board characterized by being formed.