Flip Chip Interconnection Systems and its Reliability Performance

In this paper, we discuss the impact of different flip chip interconnect schemes such as bump materials (SnAg2.5, SnAg3.5Cu0.5, Cu-pillar/SnAg2.5 cap, eNiAu, epl-Au and Au-stud), die-substrate coupling adhesives (underfill, ACF, ACP and NCP) and substrate pad finishes (ENIG, OSP and SOP) on the joint resistance and reliability performance of a common test vehicle. The integrity of the flip chip joints was assessed by both daisy-chain and 4-point resistance measurements after assembly, NTS and TC testing. It was found that the joint performance of solder interconnects is less dependent on bumping technologies and substrate pad finishes. On the other hand, the performance of non-solder interconnects is very dependent on the type of bump materials, adhesives, surface pad finishes and joint locations. However, with careful optimization, it has been demonstrated that it is possible to achieve good reliability performance that is comparable to a solder interconnect. This is an important step towards designing a robust flip chip interconnection system