Sharp Kabushiki Kaisha Corporation

Rca Inc.

Shigeo Harada

Soitiro Tosima

Katsuki Furukawa

Akira Suzuki

Yoshiyuki Higashigaki

Toshihiko Takano

Yoshio Inoue

Yukiko Kobayashi

A detector is adapted to detect the kinds and concentrations of impurity metals in molten solder or changes in the tin-lead composition of the solder by measuring the dissolution rate of a metallic film. The detector comprises a light-transmissive rod, the bottom cross-sectional area of which is covered by a metallic film. The top cross-sectional area of the rod is connected to an optical measurement means through an optical fiber cable and the time required to dissolve the metallic film in the sample molten solder is measured.

Detector of impurities in molten solder

A reversible temperature indicating material which is chemically stable, is not harmful and can be produced relatively inexpensively contains as principal component a polycrystalline bismuth-chromium oxide substance produced by firing a mixture with 50-86 molar % of bismuth-containing compounds and 50-14 molar % of chromium-containing compounds.

Reversible temperature indicating materials

A method of fabricating SiC single-crystal substrate having a large area and a high quality which is suited to mass production, said method comprises covering the surface of a silicon substrate with a uniform thin film of silicon carbide grown by the CVD method at a low temperature, and thereafter growing a single-crystal film of silicon carbide on the thin film by the CVD method at a higher temperature than in the preceeding step.

Method of fabricating single-crystal substrates of silicon carbide

The present method can determine the presence and amount of silvery white metallic impurities in a silvery white molten solder composition. In accordance with the method of this invention, a transparent substrate which has sequential layers of metal deposited on one of the surfaces thereof is prepared. A first layer is formed directly on the substrate of a thin film of a colored metal such as copper or gold. A second thicker layer of a silvery white metal, the presence and amount of which is desired to be evaluated in the solder composition, deposited over the first layer. In use, the substrate is placed in contact with the molten solder. The amount of time required for the second layer to dissolve into the solder bath and the exposed first colored layer to change color due to alloying with the metal of the solder, is measured. The time required for the color change to occur is correlated to the level of contamination of the silvery white metal in the solder bath.

Method for characterizing solder compositions

A test procedure is disclosed for evaluating the solderability properties of molten solder. In the method of this invention, a testpiece is provided which has a transparent support with a film of metal such as copper deposited on one surface of the transparent support. The surface having the metal film is immersed in the molten solder and the time required for alloying to occur and be observed through the transparent support is measured to determine rate of alloying and, thereby, the solderability properties of the molten solder under evaluation.

Growing community of inventors

Isehara, Japan

Shigeo Harada