Void control in adhesive bonding using thermosetting polymer

Voids at the bonding interface of adhesive bonding are often generated due to incomplete flowing of the polymer. Gas residues from the adjacent polymer may fill these voids to form gas bubbles. Although the empirical method had been applied for a long time to eliminate the bubbles, theoretic analysis considering the bubble behavior during bonding process is more preferable because of the better universality. The interrelationships between processing parameters and bubble deformation were investigated. A theoretic model describing those interrelationships was developed reasonably using gas diffusion theory to predict the bubble behavior. The mathematic equations of this model were deduced and the solution was obtained with some proper simplifications. Experiments under different conditions were carried out and the experimental results were contrasted with the theoretical predictions. The model errors were then analyzed. It indicated that when choosing temperatures and pressures carefully, the model could predict the bubble behavior accurately.