ELIMINATION OF FLIP CHIP ELECTROMIGRATION FAILURES USING EMBEDDED CHIP BUILD-UP TECHNOLOGY
Authors: Ray Fillion, Tan Zhang, and Charles Woychik, Ph.D. Company: General Electric Company Date Published: 10/11/2007
Abstract: Electromigration is becoming a major limitation to the performance of high-end processors packaged in solder bump, flip chip build-up carriers. These devices have under bump metallization (UBM) on the chip pads and have multi-element solder systems forming the bumps. Electromigration occurs when either the UBM migrates into the solder bump or the solder elements in the bump migrate and separate. These mechanisms cause void formation and early joint failure. These failures are becoming a larger issue as the pad pitch and corresponding pad area continue to shrink for high performance processors, pushing the current density higher. This paper will look at the causes of these failures, at the effects that smaller pad pitches and bump diameters cause and at what will happen with the planned transition from high lead to lead free solder bumps. It will then review a new family of embedded chip packaging approaches that eliminate this failure mechanism all together.