Soldering & Surface Mount Technology , No. 22, pp. 46-50, Feb. 22 1996.

Popcorning in Fully Populated and Perimeter Plastic Ball Grid Array Packages

R. Munamarty, P. McCluskey, M. Pecht, and L. Yip


To types of plastic ball grid array packages, a 225-lead full matrix. array and a 256-lead perimeter, array, ere subjected to 168 hours of moisture preconditioning at 85oC and 30% relative humidity followed by simulated Infrared reflow at temperature ramp rates of 1oC/s and 0.67oC/s. The packages ere subsequently examined for delamination and cracking using scanning acoustic microscopy and environmental scanning election microscopy. At the higher, ramp rate, delamination and cracking , were observed in both package types, originating i, the die attach and propagating along the weakest interfaces. At the lower ramp rate, a small amount of delamination was observed. This suggests that there is a critical ramp rate below which popcorn cracking does not occur.

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