Modification of solder alloy compositions to suppress interfacial void formation in solder joints

Abstract

A solder joint comprising a solder capture pad on a substrate having a circuit; and a lead containing or a lead free solder selected from the group comprising Sn—Ag—Cu solder, Sn—Cu solder and Sn—Ag solder adhered to the solder capture pad; the solder selected from the group comprising between 0.1 and 6.0 percent by weight Zn. A solder joint, comprising a solder capture pad on a substrate having a circuit; and a Sn—Cu lead free solder adhered to the solder capture pad, the solder comprising between 0.1 and 6.0% by weight Zn. Formation of voids at an interface between the solder and the solder capture pad is suppressed. A method for forming solder joints using the solders.

1 . A solder joint, comprising:
 a solder capture pad on a substrate having a circuit; and   one of a lead containing or a lead free solder, the lead free solder being selected from the group comprising Sn—Ag—Cu solder, Sn—Cu solder and Sn—Ag solder adhered to said solder capture pad;   said solder selected from said group comprising between 0.1 and 6.0 percent by weight Zn, so that formation of voids at an interface between said solder and said solder capture pad is suppressed.   
     
     
         2 . The solder joint of  claim 1 , wherein said selected solder is Sn—Cu solder. 
     
     
         3 . The solder joint of  claim 2 , wherein the solder further comprises less than 0.5% by weight Bi. 
     
     
         4 . The solder joint of  claim 3 , wherein the copper content is between 0.7 and 2.0% by weight Cu. 
     
     
         5 . The solder joint of  claim 1 , wherein said selected solder is Sn—Ag solder. 
     
     
         6 . The solder joint of  claim 1 , wherein said solder capture pad is comprised of copper. 
     
     
         7 . The solder joint of  claim 1 , wherein the solder is a SnPb solder. 
     
     
         8 . The solder joint of  claim 1 , wherein the SnPb solder contains substantially 37% by weight Pb. 
     
     
         9 . A solder joint, comprising:
 a solder capture pad on a substrate having a circuit; and   a Sn—Cu lead free solder adhered to said solder capture pad;   said solder comprising between 0.1 and 6.0% by weight Zn, so that formation of voids at an interface between said solder and said solder capture pad is suppressed.   
     
     
         10 . The solder joint of  claim 9 , wherein the solder further comprises 0.5% by weight Bi. 
     
     
         11 . The solder joint of  claim 10 , wherein the copper content is between 0.7 and 2.0% by weight Cu.