| From material side, this research extensively investigated many aspects of no-flow underfill technology for low cost flip-chip applications. In this thesis, base epoxy material systems for process-required curing characteristics for eutectic Sn/Pb solder material were first extensively studied and some qualified base material systems were developed. Low corrosive fluxing agents were then systematically investigated and several fluxing agents for the qualified base material systems were developed. The design of the no-flow underfill material system and the concept of the no-flow underfill process were proven to be practical by many assembled no-flow flip-chip packages. Some material-related factors were investigated to improve the reliability of no-flow flip-chip packages, and the correlation of package reliability with material properties was identified. A low-cost SMT (surface mount technology) facility transparent flip-chip technology called wafer-level compressive flow underfill (WLCFU) process was designed as a creative extension of the no-flow underfill technology. The feasibility of the WLCFU process was demonstrated by the developed trial WLCFU material with 50wt% silica filter loading. |
