Effect of 260 °C reflow on the ability of mold compounds to meet moisture sensitivity level one (MSL1)

While it is fairly common to achieve moisture sensitvity level 1 (MSL1) (85 degrees C/85% RH, 168 h) compliance with a standard eutectic lead/tin solder reflow range of 220 degrees C the ability to extrapolate to 260 degrees C is proving very difficult. The objective of this paper is to correlate adhesion/delamination to various mold compound properties in an attempt to determine which properties from a users standpoint are important in the selection of a proper mold compound to withstand the stresses induced by MSL1 moisture loading and subsequent reflow at 260 degrees C. A second objective of this paper is to investigate the effect mold compound properties have on their ability to adhere to copper substrates as a function of MSL1 moisture loading and simulated solder reflow at 260 degrees C. The ultimate goal is to determine whether it is possible to predict those properties that can be used as a screening method to compare and choose the best candidate compounds. Based on analysis of the data it appears that the combination of room temperature adhesion strength and low moisture absorption seem to be good predictor variables for performance of a mold compound when exposed to MSL testing.