Method to manufacture lead-free solder material having good wettability

Abstract

A solder material optimum in the melting temperature as a solder material, superior in mechanical properties and in wettability and capable of assuring excellent soldering performance. For a Sn—Zn—Bi based solder material, germanium and cooper is added, while germanium and further copper are added for a Sn—Bi—Ag based solder material and germanium and silver are added for a Sn—Zn—In based solder material.

What is claimed is:  
     
         1 . A solder material wherein a Sn—Zn—Bi alloy containing 0.5 to 10 wt % of zinc and 0.5 to 8 wt % of bismuth, with the balance being substantially tin, is added to with 0.005 to 0.5 wt % of geranium and 0.3 to 3 wt % of copper.  
     
     
         2 . A solder material wherein a Sn—Bi—Ag alloy containing 0.5 to 8 wt % of bismuth and 0.5 to 3 wt % of silver, with the balance being substantially tin, is added to with 0.01 to 0.1 wt % of germanium.  
     
     
         3 . The solder material as claimed in  claim 2  further containing 0.3 to 1 wt % of copper.  
     
     
         4 . A solder material wherein a Sn—Zn—In alloy containing 3 to 15 wt % of zinc and 3 to 10 wt % of indium, with the balance being substantially tin, is added to with 0.01 to 0.3 wt % of germanium and 0.3 to 3 wt % of silver.