CERAMIC-COATED ELECTRIC CONNECTION TERMINAL

Abstract: An electrically conductive ceramic coating layer is provided on a surface of a base material of the terminal. The conductive ceramic coating layer is made of at least one ceramic material selected from the group consisting of titanium carbide, titanium nitride, tungusten carbide, tungusten nitride, zirconium carbide, zirconium nitride, chromium carbide and chromium nitride. An electrically conductive intermediate layer is provided between a base material of the terminal and the electrically conductive ceramic coating layer.

Description: The present invention relates to a ceramic-coated terminal which is used for electrical connection. Hitherto, a terminal for electrical connection comprises a base material made of a copper-based alloy and a plated layer which is coated on the base material and made of tin (Sn), a solder, nickel (Ni), gold (Au), silver (Ag) or the like selected according to service conditions. For example, tin which is cheap is plated on the terminal for electrical connection to improve corrosion resistance of the terminal. Gold which is hardly oxidized is plated on the terminal for electrical connection, when a slight electrical current passes through the terminal for electrical connection. It is essential to plate gold, particularly in the case of the terminal which is used in a severe environment, for example, in an outdoor or under a hood of automobile in which a slight electrical current is treated. However, the tin-plating has such a problem that it has poor reliability since the terminal for electrical connection may be corroded when used for a long time. The gold-plating has such problems that it is expensive and that it has inferior mechanical properties such as abrasion resistance. A terminal according to the preamble of claim 1 is known from GB-A- 2130 795. An object of the present invention is to provide a terminal for electrical connection whereby the above problems are solved, and whereby the terminal has a good thermal resistance. This object is solved according to the present invention by a terminal with the features of claim 1. According to the present invention, a ceramic-coated terminal for electrical connection is provided wherein an electrically conductive ceramic coating layer is provided on a surface of the terminal, and an electrically conductive intermediate layer is provided between a base material of the terminal and the electrically conductive ceramic coating layer, characterized in that the base material is made of an electrically non-conductive ceramic. The electrically conductive ceramic coating layer is made of an electrically conductive ceramic, for example, at least one selected from the group consisting of titanium carbide, titanium nitride, tungsten carbide, tungsten nitride, zirconium carbide, zirconium nitride, chromium carbide and chromium nitride. The electrically conductive intermediate layer, which is optionally present, may be made of any metal, preferably at least one selected from the group consisting of nickel, copper, chromium, silver, gold, nickel/chromium, copper/nickel and copper/nickel/chromium. The electrically conductive intermediate layer and the electrically conductive ceramic coating layer have a thickness which varies with, for example, the kind of the used base material and service conditions. Usually, the electrically conductive ceramic coating layer has a thickness of a several micrometers. The electrically conductive intermediate layer can be formed on the base material by a plating method such as a vacuum deposition method. The electrically conductive ceramic coating layer can be formed on the electrically conductive intermediate layer or the base material by a spattering method, a CVD method, a plasma CVD method or an ion plating method. The present invention will be illustratively explained with reference to the accompanying drawings. The present invention, of course, is not limited to the embodiments of the drawings. Fig. 1 is a perspective view of a male tab and a female terminal representing one embodiment of the terminal for electrical connection according to the present invention. In Fig. 1, both of the male tab 1 and the female terminal 2 have, on their entire surfaces, electrically conductive layers consisting of an electrically conductive intermediate layer and an electrically conductive ceramic coating layer. The female terminal 2 has bent portions 21 and curved portions 22. The bent portions 21 and the curved portions 22 are usually formed by bending or curving a flat base material after forming the electrically conductive intermediate layer and the electrically conductive ceramic coating layer on the base material. However, the electrically conductive intermediate layer and the electrically conductive ceramic coating layer may be formed after bending or curving the base material. The electrically conductive intermediate layer or the electrically conductive ceramic coating layer never cracks or peels off through bending or curving. Since the male tab 1 and the female terminal 2 have the electrically conductive ceramic coating layer, they are non-rusting and excellent in various mechanical properties such as abrasion resistance and pulled-apart resistance. Therefore, the male tab 1 and the female terminal 2 can be used for a long time in severe circumstances. Fig. 2 is a cross-sectional view of the male tab along the line A-A′ in Fig. 1. The male tab 1 consists of the base material 3, the electrically conductive intermediate layer 4 and the outermost electrically conductive ceramic coating layer 5. In this drawing, each of elements, namely, the base material 3, the intermediate layer 4 and the outermost layer 5 is illustrated in a different size from an actual size. The terminal for electrical connection according to the present invention has good mechanical properties such as abrasion resistance and corrosion resistance, is not oxidized, and has good durability since it has the electrically conductive ceramic coating layer. The terminal also has a good thermal resistance. The good effects as mentioned above can continue after prolonged use in severe circumstances. When the electrically conductive intermediate layer has higher hardness than the base material, the electrically conductive ceramic coating layer has low possibility to peel off or crack through, for example, deformation of the base material.

Claims: A ceramic-coated terminal for electrical connection wherein an electrically conductive ceramic coating layer (5) is provided on a surface of the terminal, and an electrically conductive intermediate layer (4) is provided between a base material (3) of the terminal and the electrically conductive ceramic coating layer (5), characterized in that the base material (3) is made of an electrically non-conductive ceramic. The ceramic-coated terminal for electrical connection according to claim 1, wherein the electrically conductive ceramic coating layer (5) is made of at least one ceramic material selected from the group consisting of titanium carbide, titanium nitride, tungsten carbide, tungsten nitride, zirconium carbide, zirconium nitride, chromium carbide and chromium nitride. The ceramic-coated terminal for electrical connection according to claim 1 or 2, wherein the electrically conductive intermediate layer (4) is made of at least one material selected from the group consisting of nickel, copper, chromium, silver, gold, nickel/chromium, copper/nickel and copper/nickel/chromium.

Inventors: HAYASHI KYOZO OSAKA WORKS OF S, IKEDA H OSAKA WORKS OF SUM ELE, KAWAMURA S OSAKA WORKS OF SUM, HAYASHI, KYOZO OSAKA WORKS OF SUM. ELEC. IND. LTD., IKEDA, H. OSAKA WORKS OF SUM. ELEC. IND. LTD., KAWAMURA, S. OSAKA WORKS OF SUM. ELEC. IND. LTD.
Applicants: SUMITOMO ELECTRIC INDUSTRIES, SUMITOMO ELECTRIC INDUSTRIES LIMITED
Application year: 1987
Main classification: H01R13
IPC codes: H01H1, H01R13