| 摘要 |
PROBLEM TO BE SOLVED: To provide solder powder which is fine powder having a mean particle diameter of 5μm or smaller and reduces generation of voids in a solder bump formed after melting, and to provide paste for solder using the powder. SOLUTION: The solder powder having the mean particle diameter of 5μm or smaller has a structure comprising a central nucleus, a covering layer for covering the central nucleus, and the outermost later covering the covering layer. The central nucleus comprises Ag, Cu, Bi, Ge, Ni or In; the covering later comprises Sn; the outermost later comprises Ag, Cu, Bi or Ge; metals of the central nucleus and the outermost later are the same or different; and the content ratio of Sn is 85 to 99.9 mass%. Alternatively, the central nucleus comprises Ag, Cu, Bi, Ge, Ni or In; the covering later comprises Sn; the outermost later comprises Ag, Cu, Bi or Ge; either one or both of Bi and In is included in the powder; metals of the central nucleus and the outermost later are the same or different; and the content ratio of Sn is 35 to 60 mass%. COPYRIGHT: (C)2008,JPO&INPIT
|
