X-ray alignment system for fabricaing electronic chips

Abstract

A method of using an x-ray alignment method by replacing a Vision Camera with a commercial x-ray sub-assembly in a chip fabricating assembly. The invention aligns the gold plated receptor pads of five mils or less, disposed upon a low light contrast ceramic (9011 alumina) substrate, with a screen printing stencil having very small apertures of less than 125 microns.

What is claimed is:  
     
         1 . A method of aligning receptor pads of a low light contrast substrate with a fine pitch printing screen, comprising the steps of: 
 a) beaming x-rays at receptor pads disposed upon a substrate; and    b) aligning a printing screen with the receptor pads of the substrate in accordance with step (a), using the x-rays of step (a).    
     
     
         2 . The method in accordance with  claim 1 , wherein said printing screen is a fine pitch printing screen comprising apertures of less than approximately 125 mils.  
     
     
         3 . The method in accordance with  claim 1 , wherein said receptor pads comprise flip chip pads.  
     
     
         4 . The method in accordance with  claim 1 , wherein said receptor pads are gold plated.  
     
     
         5 . The method in accordance with  claim 1 , wherein said substrate is low contrast.  
     
     
         6 . A method of aligning receptor pads spaced no more than approximately 5 mils from one another, disposed upon a substrate, with a fine pitch printing screen having apertures of less than approximately 125 mils, comprising the steps of: 
 a) beaming x-rays at receptor pads disposed upon a substrate; and    b) aligning a printing screen with the receptor pads of the substrate in accordance with step (a), using the x-rays of step (a).    
     
     
         7 . The method in accordance with  claim 6 , wherein said receptor pads comprise flip chip pads.  
     
     
         8 . The method in accordance with  claim 6 , wherein said receptor pads are gold plated.  
     
     
         9 . The method in accordance with  claim 6 , wherein said substrate is low contrast.  
     
     
         10 . Apparatus for aligning receptor pads disposed upon a substrate, with a fine pitch printing screen, comprising: 
 receptor pads disposed upon a low light contrast substrate;    a fine pitch printing screen disposed adjacent said receptor pads;    aligning means for aligning said receptor pads of a low light contrast substrate with said fine pitch printing screen, said aligning means comprising an x-ray system for producing x-rays that are beamed toward said fine pitch printing screen and said receptor pads.    
     
     
         11 . The apparatus in accordance with  claim 10 , wherein said printing screen is a fine pitch printing screen comprising apertures of less than approximately 125 mils.  
     
     
         12 . The apparatus in accordance with  claim 10 , wherein said receptor pads comprise flip chip pads.  
     
     
         13 . The apparatus in accordance with  claim 10 , wherein said receptor pads are gold plated.  
     
     
         14 . The apparatus in accordance with  claim 10 , wherein said receptor pads are disposed no more than approximately 5 mils from one another.