Compliant interconnects for reduced cost of a ceramic ball grid array carrier

The transition to lead free solders has accentuated the inherent reliability problem in electronic packaging caused by thermo mechanical mismatch between different parts of an assembled system. To mitigate this problem, polymer core solder balls (PCSBs) have been proposed as a mechanically more flexible and therefore more reliable alternative to solid solder balls normally used for such applications. In this paper we report results from testing of PCSBs used for connecting and attaching a low temperature co-fired ceramic (LTCC) Ball Grid Array (BGA) carrier to an FR-4 board. The results appear to be strongly dependent on the assembly process. However, the results also indicate that with a properly executed assembly process, these balls represent an alternative to traditional solder balls with remarkable resistance to thermal cycling.