Flip-chip on FR-4 integrated circuit packaging

摘要: Technology advances have made it possible to extend the IBM C4 (Controlled Collapse Chip Connection) IC attachment method, also known as flip-chip, printed circuit boards with low-cost dielectrics, such FR-4. This new technology is referred Flip Attach (FCA). In past, had been limited ceramic substrates due high temperature (360/spl deg/C) required renew low tin solder on chips, and need for substrate its thermal expansion relatively closely matched that of silicon chip. The development methods deposit uniform, small (approximately 1/spl times/10/sup -3/ mm/sup 3/) volumes eutectic tin/lead cards has allowed bumped chips be reflow soldered using standard SMT joining time/temperature profiles. melt (3-5% tin, balance lead) bump chip used simply a wettable device lead in this case. resulting joint not true controlled collapse joint, but process still maintains self-aligning characteristic C4, surface tension molten mass other enabling FCA use epoxy encapsulant between minimize cyclic strain joints induced by mismatch FR-4 card. Without an encapsulant, cycle fatigue life would totally unacceptable, useless. paper we will explain how technologies work make viable packaging present reliability data several different packaging. >