METHOD FOR PRODUCING LOW Α-EMITTING BISMUTH, LOW Α-EMITTING BISMUTH, AND BISMUTH ALLOY

摘要

Provided is a bismuth characterized in that the bismuth emits 0.01 cph/cm² or less of α rays. Also provided is a method for producing a low α-emitting bismuth, characterized in that a titanium cathode and a bismuth anode are introduced to a nitric acid solution having a bismuth concentration of 5 to 50 g/L and pH of 0.0 to 0.4, and electrolytic purification is performed at a cathode current density of 0.1 to 1 A/dm². Recent semiconductor devices are high density and high capacity and therefore are subject to increased risk of soft error due to the effects of α rays emitted from materials in the vicinity of the semiconductor chips. In particular, there is a strong demand for high-purity solder materials used near the semiconductor device, and there is a demand for a low α-emitting material. Therefore, the problem of the present invention is to elucidate the phenomenon of α ray generation by bismuth and to obtain a low α ray-emitting, high-purity bismuth that can be applied to the materials which are demanded, and an alloy thereof.