Wafer level insulation underfill for die attach

摘要

A process for forming an insulation underfill for soldering semiconductor die solder balls by a solder paste on conductive traces on a support surface. The process comprises the screen printing or deposition from a syringe of thermoplastic or thermosetting epoxy columns between the solder balls, to a height equal to the standoff height of the die from the support surface. The assembly is first heated to a temperature at which the plastic becomes semifluid and before the area over which it will spread becomes contaminated with flux residue; and is next heated to the solder paste reflow temperature.