JPH02205096A - Circuit formation method for silicon carbide ceramic substrate - Google Patents

Abstract

PURPOSE:To obtain a thick conductive layer by forming a titanium deposition film at the surface of a ceramics applying plating with the metallic film of a silicon carbide ceramic film substrate, where a titanium deposition film is formed on the surface of a ceramics and further thereon nickel and gold platinum protective films are formed, as an electrode, and removing unnecessary part including the deposition film by etching. CONSTITUTION:A metallic film 2 is formed by a deposition technology at the surface of a silicon carbide ceramic substrate 1. Furthermore, this metallic thin film 2 is composed of a titanium deposition film and a protective film consisting of, for example, nickel being formed thereon. Next, a negative image 3 is formed by a dry film, making use of a photography technology, at the silicon carbide ceramics substrate 1 which obtained the metallic film 2 at the surface by deposition. Next, currents are applied with the metallic film 2 as an electrode, and by an electrolytic copper plating technology, a thick copper plated layer 4 is formed at the circuit part. Next, the negative image 3 is exfoliated by the dry film. Next, by etching the metallic film 2, a circuit 4 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application 1 The present invention relates to the field of circuit formation technology for silicon carbide ceramic substrates.

[Prior art and problem 1] Recently, in circuit formation technology for printed wiring boards, particularly, (1) high-density placement of low-resistance circuits with large capacitance on a board with good heat dissipation. ■The circuit that meets the conditions of ■ above is firmly and firmly attached to the board (adhesion).
It is strongly desired to propose a technology that can obtain a circuit that meets both of the following conditions.

On the other hand, as one of the substrates for forming circuits that meet this purpose, substrates made of silicon carbide ceramics are provided on the market.

By the way, the current state of the art for forming circuits on silicon carbide ceramic substrates is limited to the following level of technology.

a) A method in which highly active titanium is vapor-deposited onto a silicon carbide-based ceramic substrate, and another type of metal is vapor-deposited thereon.

However, the metal film obtained by this method is very thin, and if you try to make a thick metal film that satisfies the condition (2) above using this method, it will take a lot of time for vapor deposition. This would require a lot of effort, making it completely uneconomical.

b) A method of joining a conductive metal by brazing onto the vapor deposited film formed by the method described in a) above.

With this method, to form a fine circuit, three to four types of metals must be etched, including the vapor deposited layer, the wax, and the conductive metal on top, and the corrosion protection of each metal must be etched. In fact, it is very difficult to control the soldering agent and form a diffusion layer, and to etch this layer, making it impossible to form circuits with high precision.

C) A method of directly plating a silicon carbide ceramic substrate.

Because silicon carbide ceramics have extremely stable physical properties, it is difficult to chemically modify their surface to improve adhesion in metallization to a substrate, and it is difficult to meet the above condition (①). I can't.

[Object of the Invention] The object of the present invention is to propose a circuit forming technique that satisfies the conditions (2) and (2) described in the above [Prior Art and Problems 1] section for a substrate made of silicon carbide-based ceramics.

Means for Solving Problem E] In the present invention, as a result of various studies on specific techniques to achieve the above object, we first form a vapor deposited film of highly active titanium on the surface of silicon carbide ceramics, By applying electricity to a substrate on which a protective film of nickel, gold, platinum, or a combination thereof is deposited, using this metal thin film as an electrode, and applying a thick copper pad on the *i, We have completed a technology that satisfies the above-mentioned conditions (■) and can form a circuit with no thermal distortion at all.

Save! The reason for providing the film is to maintain good stability of the circuit itself, and it has been experimentally confirmed that the above-mentioned metals also provide good results in terms of etching properties during circuit formation.

An example of the use of this method (an example of circuit formation using the "semi-additive method") will be supplemented by explaining it with a diagram (FIG. 1).

First, a metal thin film (2) is formed on the surface of a silicon carbide-based ceramic substrate (1) using a vapor deposition technique.・・・・・・
- In the figure, this metal thin film (2) is made up of a titanium vapor-deposited film and a protective film made of, for example, nickel formed thereon.

Next, a negative image (3) is formed using a dry film using a photographic technique on the silicon carbide ceramic substrate (1) on which a metal thin film (2) has been obtained by vapor deposition. ...
...Figure 0 Next, electricity is applied using the thin metal 11 (2) as an electrode, and a thick copper plating layer (4
) to form. ...Figure 0 Next, the negative image (3) formed by the dry film is peeled off...Figure ■ Next, the circuit (4) is obtained by etching the metal 1F1i (2). ...Figure ■ [Example] A titanium vapor deposited film is formed on the surface of a silicon carbide ceramic substrate, and then a 0.1 μm thick film of nickel and gold is formed in that order, and after degreasing\ dry film. After forming an image, it was further degreased with 10% Hel, and after activation, 20%
Copper plating of μm, 30μm, and 50μm is performed, and after resist removal, gold etchant manufactured by the applicant of the present invention (
Etching is performed using the product name "Select Etch E-79J", and then the nickel and titanium are removed using an etchant for nickel and titanium (product name "Select Etch E-81") manufactured by the applicant of the present invention. I got it.

The images used for the study are 2. The vertical tensile strength was measured using a circular pad of O1φ, and the results are shown in [Table-■].

Margins below [Table - ■] We have truly increased the practical value of ceramic substrates and made it possible to provide superior printed wiring boards to the market.

[Brief explanation of the drawing]

FIG. 1 shows an example of a military body for implementing the present invention. It was experimentally confirmed that all of the fractures caused by the test were due to fractures on the ceramic surface, and that no stress concentration occurred at the joint surface due to the plating. Further, the resistance value of the circuit was almost the same as that of pure metal, and was significantly lower than that of the thick film paste method. [Effect of the invention 1] The present invention provides a simple and extremely reliable technique for forming a circuit to obtain a thick conductive layer on a silicon carbide ceramic substrate, which was extremely difficult using conventional methods. Yamatoya Shokai Co., Ltd., patent applicant for high-quality silicon carbide as a circuit board because of its invention

Claims (1)

[Claims] This metal thin film is applied to a silicon carbide ceramic thin film substrate on which a titanium vapor-deposited film is formed on the surface of the silicon carbide ceramic, and a protective film of nickel, gold, platinum or a combination thereof is formed on top of the titanium vapor deposited film. A circuit formation method characterized by plating as an electrode and patterning by removing unnecessary portions including the deposited film by etching.