Title:
METHOD FOR PRODUCING LOW Α-EMITTING BISMUTH, LOW Α-EMITTING BISMUTH, AND BISMUTH ALLOY
Document Type and Number:
WIPO Patent Application WO/2014/069357
Kind Code:
A1
Abstract:
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.
Inventors:
HOSOKAWA YU (JP)
ITO JUNICHI (JP)
ITO JUNICHI (JP)
Application Number:
PCT/JP2013/078949
Publication Date:
May 08, 2014
Filing Date:
October 25, 2013
Export Citation:
Assignee:
JX NIPPON MINING & METALS CORP (JP)
International Classes:
C25C1/22; B23K35/26; C22B5/12; C22B9/04; C22B9/05; C22B30/06; C22C12/00; C22C13/02
Foreign References:
| JPH10158754A | 1998-06-16 | |||
| RU2436856C1 | 2011-12-20 | |||
| JP2013185214A | 2013-09-19 |
Attorney, Agent or Firm:
OGOSHI Isamu et al. (JP)
Isamu Ogoshi (JP)
Isamu Ogoshi (JP)
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