Lead free solder

Abstract

A lead-free solder comprises tin and zinc at a weight ratio between tin and zinc ranging from about 88:12 to about 80:20 on the basis of total weight of the lead-free solder.

1 . Lead-free solder comprising tin and zinc at a weight ratio between tin and zinc ranging from about 88:12 to about 80:20.  
   
   
       2 . The lead-free solder as claimed in  claim 1 , wherein the lead-free solder essentially consists of tin and zinc at a weight ratio between tin and zinc ranging from about 88:12 to about 80:20 on the basis of total weight of the lead-free solder.  
   
   
       3 . The lead-free solder as claimed in  claim 1 , wherein the lead-free solder essentially consists of tin and zinc at a weight ratio between tin and zinc ranging from about 86:14 to about 83:17 on the basis of total weight of the lead-free solder.  
   
   
       4 . Lead-free solder comprising tin and silver at a weight ratio between tin and silver ranging from about 99.9:0.1 to about 98.0:2.0.  
   
   
       5 . The lead-free solder as claimed in  claim 4 , wherein the lead-free solder essentially consists of tin and silver at a weight ratio between tin and silver ranging from about 99.9:0.1 to about 98.0:2.0 on the basis of total weight of the lead-free solder.  
   
   
       6 . Lead-free solder comprising tin and silver at a weight ratio between tin and copper ranging from about 99.7:0.3 to about 99.0:1.0.  
   
   
       7 . The lead-free solder as claimed in  claim 6 , wherein the lead-free solder essentially consists of tin and silver at a weight ratio between tin and silver ranging from about 99.7:0.3 to about 99.9:0.1 on the basis of total weight of the lead-free solder.  
   
   
       8 . Lead-free solder comprising tin and copper at a weight ratio between tin and copper ranging from about 99.9:0.1 to about 99.5:0.5.  
   
   
       9 . The lead-free solder as claimed in  claim 8 , wherein the lead-free solder essentially consists of tin and copper at a weight ratio between tin and copper ranging from about 99.9:0.1 to about 99.5:0.5 on the basis of total weight of the lead-free solder.  
   
   
       10 . A semiconductor device comprising: 
 a first body to be bonded to a lead-free solder;    a second body to be bonded to a lead-free solder that has a different coefficient of thermal expansion than the first body; and    a lead-free solder interposed between the first body and the second body; the solder comprises tin and zinc, the zinc content of a surface in contact with the first body being larger than the zinc content of a surface in contact with the second.    
   
   
       11 . The semiconductor device as claimed in  claim 10 , wherein, the second body has a larger coefficient of thermal expansion than the first body, and wherein when the zinc content of a surface on a side of the first body is X (mass %) and the zinc content of a surface on a side of the second body is Y (mass %), X and Y satisfy the conditions,  
       23≦X≦40, and  0 ≦Y≦X− 23.