PURPOSE: To improve wettability especially wetting speed of a solder-plated wire of a double-layer construction by forming a second solder-plated layer by electric plating while specifying its residual carbon quantity in a double- construction solder-plated wire.
CONSTITUTION: In a double-construction solder-plated wire, a second solder- plated layer (plated layer of the surface layer) is formed by electric plating, and a residue carbon quantity of this second solder-plated layer is to be made 300 to 2000ppm. In case the residual carbon amount of the second layer is under 300ppm, wetting speed does not largely improve, and exceeding 2000ppm, gas generation at the time of being soldered increases so that a soldering property is impaired and liable to become rough after soldering. The desirable range of the residual carbon quantity of this second layer is 800 to 1500ppm. Thereby, the wetting characteristic of a solder-plated wire, especially wetting speed is improved.
ISHIBASHI HIROSHI
TANAKA YOSHIYUKI
HAYATA SATORU
NAKATAKI CHUICHI
