Lead-Free Solder

Abstract

[Problem]Mobile electronic equipment is often dropped during use or transport, and the soldered joints of electronic parts sometimes peel off due to the impact when dropped. In addition, they undergo heat cycles in which internal coils, resistors, and the like generate heat and soldered joints increase in temperature during operation of electronic equipment and cool off during periods of non-use. With a conventional Sn—Ag base lead-free solder, the impact resistance and resistance to heat cycles of minute portions such as solder bumps were not adequate. The present invention provides a lead-free solder alloy, bumps of which have excellent impact resistance and resistance to heat cycles. Means for Solving the Problem The present invention is a lead-free solder alloy comprising 0.1—less than 2.0 mass % of Ag, 0.01-0.1 mass % of Cu, 0.005-0.1 mass % of Zn, and a remainder of Sn, to which Ga, Ge, or P may be added, and to which Ni or Co may be further added.

1 - 3 . (canceled)  
   
   
       4 . A lead-free solder alloy comprising 0.1-less than 2.0 mass % of Ag, 0.01-0.2 mass % of Cu, 0.005-0.1 mass % of Zn, and a remainder of Sn.  
   
   
       5 . A lead-free solder alloy as claimed in  claim 4  further comprising at least one of Ga, Ge, and P in an amount of 0.0005-0.1 mass %.  
   
   
       6 . A lead-free solder alloy as claimed in claim  1  further comprising at least one of Ni and Co with a total amount of Ni and Co being 0.01-0.1 mass %.  
   
   
       7 . A lead-free solder alloy as claimed in claim  1  consisting of 0.1-less than 2.0 mass % of Ag, 0.01-0.2 mass % of Cu, 0.005-0.1 mass % of Zn, at least one of Ga, Ge, and P in an amount of 0-0.1 mass %, at least one of Ni and Co with a total amount of Ni and Co being 0-0.1 mass %, and a remainder of Sn.  
   
   
       8 . A solder bump formed from the lead-free solder as claimed in  claim 4.