Moisture absorption and mechanical performance of surface mountable plastic packages

摘要: The results of moisture-absorption tests on 68L plastic-leaded chip-carriers (PLCC) are presented. Environmental variables include both temperature (30, 40, 50, 60 and 85 degrees C) relative humidity (24, 85%). Control samples pure molding compound were tested to determine the effect leads PLCC samples. Comparison was made between absorbed moisture measurements predictions based one-dimensional Fickian diffusion solution. Nonlinear regression analysis indicates that behavior represents actual absorption for humidities below 85%. At 85% RH, however, deviation becomes significant after 500 hr. On basis agreement at moderate values time, analytical models developed show mass gain coefficient. A stress deformation performed predict envelope in parameter space separating cracked uncracked packages. model used depends presence saturated water die paddle compound. Doming plastic underneath is attributed flashing all trapped liquid steam. >