DEVELOPMENT OF LEAD-FREE COMPATIBLE MOLDED UNDERFILL (MUF) MATERIALS FOR FLIP CHIP STACKED PACKAGING: KEY CHALLENGES AND LEARNINGS

摘要

This paper reports the structure-properties-performance relationship of various molded underfill materials for potential applications in flip-chip MMAP (FCMMAP) and mixed technology (FC and WB) stacked CSP (MTsCSP) packages. Chemical, rheological, and thermo-mechanical properties of five high temperature reflow compatible materials were characterized and relationship to materials processability & package reliability performance were investigated. Materials having higher filler concentration and lower coefficient of thermal expansion tended to exhibit improved HTR compatibility due to improved moisture resistance and decreased CTE mis-match.