Title:
BISMUTH OR BISMUTH ALLOY HAVING SMALL AMOUNT OF α-RAY, AND METHOD FOR PRODUCING THE SAME
Document Type and Number:
Japanese Patent JP2013185214
Kind Code:
A
Abstract:
To suppress the amount of α-rays of bismuth which is the main raw material to 0.01 cph/cm2 or less to prevent generation of soft error by highly purifying a solder material used close to a semiconductor device.
An α-ray radiation from bismuth immediately after melting/casting includes the influence of an isotope having a half life of several years to tens of years. This is probably not caused by bismuth itself but caused by radioactive isotopes such as uranium, thorium, and lead which are present as impurities. Therefore, the purification of bismuth is performed by an electrolytic process in which only acid is used to remove the radioactive isotopes such as uranium, thorium, and lead which are present as impurities.
More Like This:
Inventors:
KANO MANABU
Application Number:
JP2012051645A
Publication Date:
September 19, 2013
Filing Date:
March 08, 2012
Export Citation:
Assignee:
JX NIPPON MINING & METALS CORP
International Classes:
C22B30/06; B23K35/26; C22C1/02; C22C12/00; C22C13/02; C25C1/22; H01L23/29; H01L23/31
Domestic Patent References:
| JPH09255339A | 1997-09-30 | |||
| JPS63203731A | 1988-08-23 | |||
| JP2010156052A | 2010-07-15 | |||
| JP2002180226A | 2002-06-26 | |||
| JPH10158754A | 1998-06-16 | |||
| JP2009097072A | 2009-05-07 | |||
| JP2002285371A | 2002-10-03 | |||
| JP2754030B2 | 1998-05-20 |
Foreign References:
| RU2436856C1 | 2011-12-20 |
Attorney, Agent or Firm:
Isamu Ogoshi
Ikki Kogoshi
Ikki Kogoshi