Polymer collar for solder bumps

摘要

A method of forming a polymer support ring, or collar, around the base of solder balls used to form solder joints includes forming patterned regions of uncured polymer material over each of the conductive solder bump pads on an IC package or other substrate to which the solder balls are to be attached. Preferably, the uncured polymer material is a no-flow underfill material that fluxes the solder bump pads. Pre-formed solder balls are then placed into the uncured polymer material onto their respective solder bump pads. A subsequent heating cycle raises the assembly to the reflow temperature of the solder balls, thereby attaching the solder balls to the underlying solder bump pads, and at least partially curing the polymer material to form a support collar at the base region of each attached solder ball.