Propensity for Pad Cratering Evaluation in Board Resin and Board-Resin/Glass Interface Under Assembly and Rework

Abstract In this investigation, we have systematically approached the problem by analyzing the bulk behavior of the resins using a tensile dogbone specimen and then moving forward with a bent specimen for the glass-resin interfaces. The first bulk study consists of 12 different resin formulations in which material property changes were studied under two reflow and six reflow cycles. In the second part, a four-point bend interface specimen was used. The interface behavior was measured for 30 glass-resin interfaces consisting of 15 resin types and 3 glass styles as a function of mode-I stress intensity factor to pristine, 2 reflow and 6 reflow conditions. The effect of reflow cycles was investigated by reporting perc-change in the Mode-I stress intensity factor and using this metric to rank the interfaces. In the end, an effort was made to create a predictive regression model with predictors being material properties of the samples such as elastic modulus, toughness, UTS, elongation of the resins, glass transition temperatures, and environmental conditions such as reflow cycles. Linear regression methods were applied to quantify the predictive power and compare the model performance using the mean square error (MSE) method.