Optimizing Processes and Materials for Flip Chip Reliability

The optimization of processes and materials for flip chip reliability is discussed. A test matrix of five capillary flow underfill materials and three solder mask materials has been analyzed using analytical and emperical tools. Acoustic micro imaging has been used to nondestructively image the underfill features. It has been shown that careful material selection for substrate, solder mask, and underfiller can yield assemblies with reliabilities of at least 2,000 thermal cycles at -55°C/125°C.