Z. Wang, M. Chouhdry, International Rectifier, Temecula, CA

Summary: Solder bump de-lamination failure mechanism is studied in depth. Evidence of de-lamination between bond pad metal and TiW layer and fracture within the Al layer, evidence of initial fracture at the bump neck due to nitride film stress are collected. The failure mechanism is concluded to be preexisting defective/weak bump interface activated by cyclic stress under ultrasonic wash during module assembly process.