Patent ID: 6271109
Filing Date: 2001-08-07
Classification: H01L,H05K,Y02P

Abstract:
A method for assembling a semiconductor device having a plurality of terminals on a warped surface onto a substrate having an electrically insulating surface including a plurality of discrete metallic areas in locations matching the locations of said device terminals, said areas further having at least one characteristic suitable for accommodating said device warping, comprising the steps of:forming an array of solder balls attached to said device terminals so that each terminal is contacted by one of said solder balls;mechanically aligning said solder balls so that each solder ball is placed into alignment with one of said metallic areas on said substrate;contacting said solder balls and said metallic substrate areas, as completely as permitted by said device surface warping;applying energy such that said substrate and said device increase in temperature and transfer heat to said solder balls, causing said solder balls to reach a liquid state;dwelling for metallurgical interaction, thereby activating said substrate area characteristic to cause said liquid solder balls to become thinner, resulting in lower solder joint heights, and to accommodate said device warping, resulting in device alignment substantially parallel to said substrate; andremoving said energy such that said solder balls cool and harden, forming physical bonds between said solder balls and said metallic areas.