Bumping Electronic Components Using Transfer Substrates

Abstract

A method for forming solder bumps on an electronic component. Providing a transfer substrate having a plurality of solder balls, disposing the transfer substrate on the surface of the electronic component, heating to reflow the solder balls onto the electronic component; and removing the sacrificial substrate. The transfer substrate may comprise a sacrificial film and a metal layer patterned with a mask which is used to form solder balls on the transfer substrate. Or, the transfer substrate may comprise a sheet of material having solder balls embedded at least partially in the sheet. A method of aligning a part being bumped with a transfer substrate, using a shuttle mechanism and an alignment film is disclosed.

1 - 20 . (canceled) 
     
     
         21 . A method for forming solder bumps on a circuitized substrate comprising the steps of:
 providing a transfer substrate comprising a sacrificial substrate and plurality of preformed solder balls;   disposing the transfer substrate on the surface of the circuitized substrate;   reflowing the solder balls onto the circuitized substrate; and   removing the transfer substrate;   wherein:   the transfer substrate comprises a sheet of material selected from the group comprising metal, ceramic and glass; and   the solder balls are at least partially embedded in a surface of the transfer substrate.   
     
     
         22 . The method of  claim 21 , wherein:
 the solder balls extend at least partially out of the surface of the transfer substrate.   
     
     
         23 . The method of  claim 21 , wherein:
 the transfer substrate is removed after solder balls have solidified on the circuitized substrate.   
     
     
         24 . The method of  claim 21 , wherein:
 the transfer substrate is reusable.   
     
     
         25 . The method of  claim 21 , wherein:
 the transfer substrate is a substantially planar sheet having a substantially planar front surface, a thickness, and a back surface.   
     
     
         26 . The method of  claim 21 , wherein:
 the transfer substrate comprises a sheet of a rigid or semi-rigid material.   
     
     
         27 . The method of  claim 21 , wherein:
 the transfer substrate comprises a non-wettable material.   
     
     
         28 . The method of  claim 21 , wherein:
 the transfer substrate comprises holes or depressions extending only partially through the substrate into a front surface thereof.   
     
     
         29 . The method of  claim 28 , wherein:
 the holes or depressions comprise one of the following geometries: dished out, and hemispherical.   
     
     
         30 . The method of  claim 21 , wherein:
 the transfer substrate is substantially see-through.   
     
     
         31 . The method of  claim 21 , further comprising:
 prior to heating, urging the transfer substrate against the circuitized substrate.   
     
     
         32 . The method of  claim 31 , further comprising:
 urging the transfer substrate against the electronic component using a pressure plate and a sheet of resilient material disposed between the pressure plate and the transfer substrate.   
     
     
         33 . The method of  claim 21 , wherein:
 the transfer substrate is removed before cooling.   
     
     
         34 . The method of  claim 21 , wherein:
 the solder balls are at least 50% embedded in the transfer substrate.   
     
     
         35 . The method of  claim 21 , wherein:
 the circuitized substrate is an electronic component.