Patent ID: 6513701
Filing Date: 2003-02-04
Classification: B23K,H05K

Abstract:
A method of making at least one electrically conductive contact on a substrate, said method comprising the steps of:providing a substrate with a surface having at least one circuitized feature thereon; applying a layer of solder paste over said surface of said substrate and at least a portion of said at least one circuitized feature; providing a mask, having a top surface and a bottom surface, and at least one opening therein; orienting said mask such that said at least one opening in said mask is aligned with said at least one circuitized feature; positioning said bottom surface of said mask on said layer of said solder paste; directing a radiation beam having a beam diameter larger than said mask opening on said solder paste through said opening in said mask, and selectively heating substantially only said solder paste over said at least one circuitized feature through said mask under said opening sufficiently to melt said solder paste over said at least one circuitized feature to form a substantially solid conductive solder bump commensurate with said mask opening on said at least one circuitized feature while not significantly heating the remainder of said solder paste over said surface of said substrate or substantially altering the configuration thereof; removing said mask; and removing said solder paste that was not significantly heated.