Defect control in epoxy dry film with improved electric performances

Advanced adhesive film materials, such as embedded capacitor materials, insulating built-up films, underfill films, die attach films and etc, which have the superiorities of flexibility, controllable thickness, large size, and easy processing, have been widely used in electronic packaging. The reliability of electronic devices is directly related to the internal defects existing in the materials. Under high temperature and high electric field, the space charges in the polymer will accumulate at the interface around the defect. When the density of charge carriers approaches a critical value, the electric components will be brokendown. Herein, we try to prevent the formation of defects like pores and pits in epoxy based composite films and the relevant mechanism is investigated. The surface morphology of the films is modified by adding a defoamer and a leveling agent. The defoamer agent can assist the breakage and elimination of bubbles. The leveling agent can improve the flowability of the half-dry film and then fill the pits formed after the breakage of bubbles. The effect of defects on the Weibull distribution of electric breakdown strength of the epoxy composite films has been analyzed. It proves that high electric breakdown strength can be achieved on the film with improved surface morphology. This study gives a guide for designing high quality epoxy films with improved electrical performance.