Pb-free solder alloy, and solder material and solder joint using same

Abstract

A solder alloy based on an Sn—Zn—In—Ag system contains, in weight, 3.0%<Zn<5.0%, 0.1%<In<4.0%, 0.1%<Ag<0.4%, and the balance Sn. Therefore, the current Sn—Pb soldering method can be employed as it is. Further, a Pb-free solder material having a solder characteristic with excellent bonding strengths of the parts can be provided. Still further, since a difference between a solidus temperature and a liquidus temperature is small, floating of the parts leads can be suppressed, even in case where packaging processes are performed many times over. Still further, when the joint is exposed to the high temperature and high humidity atmosphere, the bonding strength can be prevented from being lowered.

1 . A solder alloy based on an Sn—Zn—In—Ag system, the solder alloy comprising, in weight: 
 3.0%<Zn<5.0%;    0.1%≦In≦4.0%;    0.1%≦Ag≦0.4%; and    the balance Sn.    
     
     
         2 . A Pb-free solder material comprising a solder alloy and a flux, wherein the solder alloy is based on an Sn—Zn—In—Ag system having, in weight: 
 3.0%<Zn<5.0%;    0.1%≦In≦4.0%;    0.1%≦Ag≦0.4%; and    the balance Sn.    
     
     
         3 . A solder alloy based on an Sn—Zn—In—Ag system and having at least one element selected from the group consisting of Ni, Ti, Mg, Al, and Co, the solder alloy comprising, in weight: 
 3.0%<Zn<5.0%;    0.1%≦In≦4.0%; and    0.1%≦Ag≦0.4%,    wherein a total concentration of said at least one element is in the range from about 0.001% to about 0.05% in weight, and the remaining portion thereof is Sn.    
     
     
         4 . A Pb-free solder material comprising a solder alloy and a flux, wherein the solder alloy has at least one element selected from a group consisting of Ni, Ti, Mg, Al, and Co, based on an Sn—Zn—In—Ag based solder alloy having: 
 3.0%<Zn<5.0%;    0.1%≦In≦4.0%; and    0.1%≦Ag≦0.4%,    wherein a total concentration of said at least one element is in the range from about 0.001 to about 0.05% in weight and the remaining portion thereof is Sn.    
     
     
         5 . A solder joint of electrical and electronic equipment comprising the solder alloy of  claim 1 .  
     
     
         6 . A solder joint of electrical and electronic equipment comprising the solder alloy of  claim 3.