Solder bumps formation using solder paste with shape retaining attribute

Abstract

Method of forming solder bumps of an integrated circuit package is described. A solder paste is formed from a material having a characteristic that the deposited instances thereof substantially retain their geometric shape upon exposure to electromagnetic radiation.

1 . A solder paste comprising: 
 a metal;    a solder flux; and    a poly(caprolactone) additive.    
     
     
         2 . The solder paste of  claim 1 , wherein the solder paste has a property of its deposition instances substantially retaining their geometric shapes upon exposure to electromagnetic radiation.  
     
     
         3 . The solder paste of  claim 2 , wherein the poly(caprolactone) additive has a property of enabling an increase in surface rigidity of the deposition instances upon exposure to the electromagnetic radiation.  
     
     
         4 . The solder paste of  claim 1 , wherein the poly(caprolactone) additive has a property of decomposing at a temperature at which deposition instances of the solder paste reflow.  
     
     
         5 . The solder paste of  claim 1 , wherein the metal comprises tin.  
     
     
         6 . The solder paste of  claim 5 , wherein the metal further comprises lead.  
     
     
         7 . The solder paste of  claim 1 , wherein the poly(caprolactone) additive includes a backbone being thermally degradable at a temperature at which deposition instances of the solder paste reflow.  
     
     
         8 . The solder paste of  claim 1 , further comprising a crosslinkable moiety grafted to the poly(caprolactone) additive for making the poly(caprolactone) additive photo-crosslinakable.  
     
     
         9 . The solder paste of  claim 8 , wherein the crosslinkable moiety is a selected one of acrylates, methacrylates, aromatic epoxies, and aliphatic epoxies.  
     
     
         10 . The solder paste of  claim 9 , wherein the crosslinkable moiety is a methacrylate crosslinkable by a photo-radical initiator.  
     
     
         11 . The solder paste of  claim 9 , wherein the crosslinkable moiety is an aromatic epoxy crosslinkable by a photo-anionic initiator.  
     
     
         12 . The solder paste of  claim 9 , wherein the crosslinkable moiety is an aliphatic epoxy crosslinkable by a photo-cationic initiator.