MESO-SCALE ANALYSIS OF INTERFACE ROUGHNESS EFFECT ON DELAMINATION OF POLYMER/METAL INTERFACES

摘要

Delamination is one of the major failure modes occurring in micro- and nano-electronics. In the past, several numerical techniques have been applied to predict the delamination behavior of such electronic devices, such as the J-integral, VCCT, cohesive zone elements and the area release energy approach. Although these methods have been applied successfully, they suffer from a major drawback: due to their phenomenological character, these continuum-scale models rely on extensive experimental characterisation to quantify the model parameters. A multi-scale approach could possibly prevent such extensive characterisation work. Here, information resulting from interactions at different scales are incorporated in the continuum-based models. This paper investigates the effect of one of such interaction at the meso-scale, mechanical interlocking, on delamination of a metal-polymer interface. A meso-scale numerical fracture mechanics model is developed. The model consists of two materials bonded solely by chemical and physical interactions. The mechanical interlocking is taken into account by the geometric profile of the interface. Consequently, macroscopic delamination is assumed to be determined by adhesive failure, cohesive failure or a combination of both at the meso-scale. The model is used to quantitatively predict the competition between cohesive and adhesive failure dependent on characteristic interface roughness parameters. An alternative semi-analytic approach is suggested to decrease computational costs. A validation method for the meso-scale analysis is presented. It consists of peel tests and surface analysis of the original and delaminated interfaces to verify the amount of cohesive and adhesive failure. It is proposed to utilize the mesoscale model to quantify macroscopic interface properties while incorporating the influence of the surface roughness. These properties can be used in macro-scale analysis.