| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a manufacturing method for high purity tin for semiconductor, for example, high purity tin to be used for solder, BAG(ball grid array), etc. SOLUTION: Nitric acid is added to a heated aqueous soln., to which crude metallic tin is added, whereby metastannic acid is settled and is filtrated off. The obtd. metastannic acid is washed, the washed metastannic acid is dissolved by hydrochloric acid or hydrofluoric acid and the metallic tin of >=5N is obtd. by electrolysis with this dissolved liq. as an electrolytic soln. Otherwise, the metastannic acid is settled and is filtrated off by electrolytic oxidation using an anode consisting of crude metallic tin with a nitric acid liq. as an electrolytic soln. The obtd. metastannic acid is washed, the washed metastannic acid is dissolved by hydrochloric acid or hydrofluoric acid and the metallic tin of >=5N is obtd. by electrolysis with this dissolved liq. as an electrolytic soln. again.</p> |
