Microvia reliability improvement for high density interconnect substrate

High density interconnect (HDI) flip-chip ball grid arrays (FCBGA) substrate becoming more and more popular for high end applications, to meet greater number of I/O pads, increasing I/O pad density, higher operational frequencies and smaller package body size. Microvia in HDI substrate has much smaller scale comparing to conventional plated through-hole (PTH) substrate, which is prone to have microvia crack under thermal mechanical loading. This study shows that additional etching on via interface could improve microvia integrity.