The Terminal Protection Effect by Underfill Material on the Ceramic BGA Package Mounting Sample under Thermal Shock Cycling

Abstract

LSI packages for high-reliability space-use are hermetically sealed ceramic with cavities. In recent years, in order to increase the number of inputs & outputs (I/O) or pads and reduce size and weight, ceramic Ball-Grid-Array (BGA) packages have become more common and thermal cycle tolerance has become a significant issue in substrate mounting. Underfill material is often applied to improve the thermal cycle tolerance, but there are failures where the underfill peels off from the bottom of the package early in the thermal cycle test. In this paper, we report on an underfill material that protected the terminals without peeling off under a thermal cycling load of more than 3,000 cycles. We also report on indications of defects found in areas other than solder balls or connecting areas.