Thermal cycle reliability of PBGA/CCGA 717 I/Os

Status of thermal cycle test results for a nonfunctional daisy-chained peripheral ceramic column grid array (CCGA) and its plastic ball grid array (PBGA) version, both having 560 I/Os, were presented in last year´s conference. Test results included environmental data for three different thermal cycle regimes (-55deg/125degC, -55/100degC, and -50deg/75degC). Update information on these - especially failure type for assemblies with high and low solder volumes - were presented. The thermal cycle test procedure followed those recommended by IPC-9701 for tin-lead solder joint assemblies. revision A of this specification covers guideline thermal cycle requirements for Pb-free solder joints. Some background information discussed during release of this specification with its current guideline recommendations was also presented. In a recent reliability investigation a fully populated CCGA with 717 I/Os were also considered for assembly reliability evaluation. The functional package is a field-programmable gate array that has much higher processing power than its previous version. This new package is smaller in dimension, has no interposer, and has a thinner column wrapped with copper for reliability improvement. This paper will also present thermal cycle test results for this package assembly and its plastic version with 728 I/Os, both of which were exposed to three different cycle regimes. Two cycle profiles were those specified by IPC-9701 A for tin-lead, i.e. -55 to 100degC and -55 to 125degC and one was a cycle profile specified by Mil-Std-883, i.e., -65degC /150degC which is generally used for ceramic hybrid packages. Per IPC-9701 A, test vehicles were built using daisy chain packages and were continuously monitored. The effects of many process and assembly variables - including corner staking commonly used for improving resistance to mechanical loading such as drop and vibration loads - were also considered as part of the test matrix. Optical photomicrographs were tak- - en at various thermal cycle intervals to document damage progress and behavior. Representative samples of these along with cross-sectional photomicrographs at higher magnification taken by scanning electron microscopy (SEM) to determine crack propagation and failure analyses for packages are also presented