Pressurized underfill cure

Abstract

To prevent formation of entrapped underfill material between solder balls and bonding bumps, fast temperature ramping is employed during a chi assembly after application of an underfill material prior to bonding. Voids formed within the underfill material are subsequently removed by curing the underfill material in a pressurized environment. Temperature cycling on the underfill material is limited during the bonding process in order to maintain viscosity of the underfill material prior to the cure process in the pressurized environment. Further, the underfill material is subjected to the pressurized environment until the cure process is complete to prevent re-formation of voids. The cure process can be a constant temperature or a multi-temperature process including temperature ramping. Further, the cure process can be a constant pressure process or a pressure cycling process that accelerates removal of the voids.