Patent ID: 7459794
Filing Date: 2008-12-02
Classification: H01L

Abstract:
1. A substrate for device bonding, comprising an electrode layer and a solder layer formed on the electrode layer, wherein the solder layer is a Pb-free solder layer comprising: (1) a base metal layer comprising (i) Sn, (ii) Sn and Au, or (iii) In, (2) one or more melting point-lowering metal layers each of which comprises at least one metal selected from the group consisting of Bi, In (only in the case where the base metal is Sn, or Sn and Au), Zn, Au (only in the case where the base metal is In) and Sb, and (3) one or more surface-smoothing metal layers each of which comprises at least one metal selected from the group consisting of Ag, Ni, Fe, Al, Cu and Pt, and each of the melting point-lowering metal layers is adjacent to any one of the surface-smoothing metal layers.