The Effect of Die Size on the Thermal Fatigue Reliability and Failure Mode of a Chip Array BGA
Authors: Richard Coyle, Jim Wilcox, Peter McClure, Michael Meilunas, Richard Popowich, Charmaine Johnson Company: Nokia Bell Labs, Universal Instruments Date Published: 9/17/2017
Abstract: Accelerated thermal cycling (ATC) tests were performed to evaluate the effect of die size on the thermal fatigue reliability and failure mode of a 192 I/O, 14 mm x 14 mm body size chip array ball grid array (CABGA) package. The daisy chained packages were fabricated with square 12 mm, 9.5 mm, or 7.2 mm die to produce diagonal die to package ratios of 0.86, 0.68, and 0.51 respectively. Pb-free SAC305 solder (Sn3.0Ag0.5Cu) was used for the solder spheres and solder paste for surface mount assembly. In a previous paper, results were reported for an ATC profile of -40 to 125°C (IPC 9701 TC3). This paper reports results for a test profile of 0 to 100°C (IPC 9701 TC1) and completes the study. The results from the two different thermal cycling profiles are compared and discussed in terms of the influence of die size on time to failure, the failure location in the package, and the failure mode. Optical and scanning electron microscopy of the crack paths are used to characterize the failure mode.