Flip Chip Underfill and Flux Residue with Lead Free

摘要

This study evaluated a number of material sets for lead-free processes. The tacky flux and underfill systems are designed for the flip chip packaging process. The movement to a lead-free process affects the moisture level rating of packages and devices. One of the materials that impacts this JEDEC moisture level rating is the underfill. This study shows that some flux residue/underfill systems are suitable for lead-free processes. Flux Systems G, L, N, and P are more compatible to different underfill material sets than others. Underfill System B, developed with a chemistry specifically designed to interact with flux residues and meet JEDEC level 3/260℃ requirements, shows excellent compatibility with almost all the flux residues.