Solder Alloy for Power Devices and Solder Joint Having a High Current Density

Abstract

A solder joint which is used in power devices and the like and which can withstand a high current density without developing electromigration is formed of a Sn—Ag—Bi—In based alloy. The solder joint is formed of a solder alloy consisting essentially of 2-4 mass % of Ag, 2-4 mass % of Bi, 2-5 mass % of In, and a remainder of Sn. The solder alloy may further contain at least one of Ni, Co, and Fe.

1 - 6 . (canceled) 
     
     
         7 . A solder alloy for an electronic device having a joint carrying a current with a current density of 5-100 kA/cm 2 ′ consisting of 2-4 mass % of Ag, 2-4 mass % of Bi, 2-5 mass % of In, and a remainder of Sn. 
     
     
         8 . A solder alloy as set forth in  claim 7 , consisting of 2.5-3.5 mass % of Ag, 2-3 mass % of Bi, 3-4 mass % of In, and a remainder of Sn. 
     
     
         9 . A solder alloy as set forth in  claim 7 , further containing at least one element selected from 0.01-0.3 mass % of Ni, 0.01-0.32 mass % of Co, and 0.01-0.1 mass % of Fe. 
     
     
         10 . A solder joint characterized by being made of a solder alloy consisting of 2-4 mass % of Ag, 2-4 mass % of Bi, 2-5 mass % of In, and a remainder of Sn, wherein the solder joint is a solder joint inside an electronic device or a solder joint which is connected to an electronic device, and wherein a current with a current density of 5-1 00 kA/cm 2  flows through at least a portion of the solder joint. 
     
     
         11 . A solder joint as set forth in  claim 10 , wherein the solder joint is made from a solder alloy consisting of 2-4 mass % of Ag, 2-4 mass % of Bi, 2-5 mass % of In, and a remainder of Sn and further containing at least one of 0.01-0.3 mass % of Ni, 0.01-0.32 mass % of Co, and 0.01-0.1 mass % of Fe. 
     
     
         12 . A power device characterized by having a solder joint inside the device made from a solder alloy consisting of 2-4 mass % of Ag, 2-4 mass % of Bi, 2-5 mass % of In, and a remainder of Sn wherein a current density of 5-100 kA/cm 2  flows through at least a portion of the joint.