Selectively coating bond pads

Abstract

Solder ball bond pads and wire bond pads may be selectively coated so that the wire bond bond pads have a thicker gold coating than the solder ball bond pads. This may reduce the embrittlement of solder ball joints while providing a sufficient thickness of gold for the wire bonding process. In general, gold coatings are desirable on electrical contact surfaces to prevent oxidation. However, the thickness of gold which is necessary on solder ball bond pads may be less and excessive gold may be disadvantageous. Thus, by masking the solder ball bond pads during the gold coating of the wire bond bond pads, a differential gold thickness may be achieved which is more advantageous for each application.

What is claimed is:  
     
         1 . A method of coating solder ball and wire bond bond pads comprising: 
 masking said solder ball bond pads; and    coating gold on said wire bond bond pads with said solder ball bond pads masked.    
     
     
         2 . The method of    claim 1    including providing a different gold coating thickness on said solder ball bond pads and said wire bond bond pads.  
     
     
         3 . The method of    claim 2    including providing a thicker gold coating on said wire bond bond pads than on said solder ball bond pads.  
     
     
         4 . The method of    claim 3    including providing a gold coating, on said wire bond bond pads, having a thickness of about 0.5 microns and providing a solder ball bond pad gold coating of approximately 0.1 to 0.3 microns in thickness.  
     
     
         5 . The method of    claim 1    including nickel coating said solder ball and said wire bond bond pads at the same time before coating said wire bond bond pads with gold.  
     
     
         6 . The method of    claim 1    including coating said wire bond bond pads with a first gold coating and coating both of said solder ball bond pads and said wire bond bond pads with a second gold coating.  
     
     
         7 . The method of    claim 6    wherein said second gold coating is thinner than said first gold coating.  
     
     
         8 . The method of    claim 1    including using an electroless plating technique to coat gold on said wire bond bond pads.  
     
     
         9 . The method of    claim 1    including forming a laminate structure having solder ball bond pads and wire bond bond pads on the same surface.  
     
     
         10 . The method of    claim 1    wherein said solder ball bond pads are gold coated in a single step.  
     
     
         11 . The method of    claim 10    including coating said solder ball bond pads and said wire bond bond pads while the other of said solder ball and wire bond bond pads is masked.  
     
     
         12 . A method of coating two different types of bond pads on the same surface comprising: 
 masking off a first type of bond pad; and    coating a metal on the second type of bond pad with said first type of bond pad being masked.    
     
     
         13 . The method of    claim 12    including masking solder ball bond pads.  
     
     
         14 . The method of    claim 13    including coating metal on wire bond bond pads.  
     
     
         15 . The method of    claim 14    including coating gold on said wire bond bond pads.  
     
     
         16 . The method of    claim 15    including unmasking said solder ball bond pads and coating a metal on both said wire bond bond pads and said solder ball bond pads.  
     
     
         17 . The method of    claim 12    including providing different coating thicknesses on said first and second types of bond pads.  
     
     
         18 . The method of    claim 12    including coating gold on said second type of bond pad.  
     
     
         19 . The method of    claim 18    wherein said first type of bond pad is a solder ball bond pad and said second type of bond pad is a wire bond bond pad, coating gold on said wire bond bond pad to a thickness of about 0.5 microns and coating gold on said solder ball bond pads to a thickness of about 0.1 to about 0.3 microns.  
     
     
         20 . The method of    claim 19    including nickel coating said first and second types of bond pads at the same time before coating said wire bond bond pads with said metal.  
     
     
         21 . The method of    claim 12    including coating both said first and second types of bond pads with said metal after coating said metal on said second type of bond pad.  
     
     
         22 . The method of    claim 12    including masking off said second type of bond pad and coating metal on said first type of bond pad.  
     
     
         23 . A method of forming solder ball and wire bond bond pads comprising: 
 forming a solder ball bond pad;    coating gold over said solder ball bond pad;    forming a wire bond bond pad; and    coating gold over said wire bond bond pad to a thickness greater than said gold coating over said solder ball bond pad.    
     
     
         24 . The method of    claim 23    including masking said solder ball bond pad and coating gold on said wire bond bond pad with said solder ball bond pad masked.  
     
     
         25 . The method of    claim 24    including providing a gold coating on said wire bond bond pad having a thickness of about 0.5 microns.  
     
     
         26 . The method of    claim 23    including providing a gold coating on said solder ball bond pad of approximately 0.1 to 0.3 microns in thickness.  
     
     
         27 . The method of    claim 23    including coating said wire bond bond pads with a first gold coating and coating both of said solder ball and said wire bond bond pads with a second gold coating.  
     
     
         28 . The method of    claim 23    including coating said solder ball bond pad to a thickness of approximately 0.25 microns.  
     
     
         29 . A method of forming solder ball and wire bond bond pads comprising: 
 masking said solder ball bond pad;    coating gold over said wire bond bond pad;    masking said wire bond bond pad; and    coating gold over said solder ball bond pad.    
     
     
         30 . The method of    claim 29    including coating said wire bond bond pad with gold to a thickness greater than the gold coating over said solder ball bond pad.  
     
     
         31 . A packaged integrated circuit device comprising: 
 a plurality of gold coated solder ball bond pads;    a plurality of gold coated wire bond bond pads; and    the gold coating on said solder ball bond pads being thinner than the gold coating on said wire bond bond pads.    
     
     
         32 . The device of    claim 31    wherein the thickness of the gold on said solder ball bond pads is sufficiently low to reduce the likelihood of solder ball joint embrittlement.  
     
     
         33 . The device of    claim 31    wherein said solder ball bond pads have a gold coating having a thickness of between about 0.1 and 0.3 microns.  
     
     
         34 . The device of    claim 33    wherein said solder ball bond pad gold coating has a thickness of about 0.25 microns.  
     
     
         35 . The device of    claim 33    wherein said wire bond bond pads have a gold coating thickness of approximately 0.5 microns.  
     
     
         36 . The device of    claim 31    wherein said solder ball bond pads and said wire bond bond pads are all contained on the same planar surface.