Reliability and failure analyses of thermally cycled ball grid array assemblies

The reliability of ball grid arrays (BGAs) was assessed as part of a consortium effort led by the Jet Propulsion Laboratory. Nearly 200 test vehicles, each with four packages, were assembled and tested using an experiment design. The most critical variables incorporated in for the experiment were package types, ceramic and plastic; board materials, FR-4 and polyimide; surface finishes, OSP, HASL, and Ni/Au; solder volumes, low, standard, and high; and environmental conditions. Thermal cycling test results to 3000 cycles for ceramic packages with 625 inputs/outputs (I/Os) and depopulated full array plastic packages with 313 I/Os were presented in a previous paper by the authors (see Proc 30th Int. Symp. Microelectron., Philadelphia, PA, Oct. 1997, p. 396-400). This paper presents the most current thermal cycling test results (>6000 cycles) for plastic OMPAC and SuperBGA packages with 352 I/Os and 560 I/Os. Failure mechanisms detected by electrical continuity interruptions as well as optical and scanning electron microscopy results are also compared for ceramic and plastic package assemblies.