Molecular Interactions at Metal/Polyimide Interfaces: A Correlation with Adhesion nd Bond Durability

Abstract : Molecular interactions between a substrate and an overlayer control the intrinsic adhesion between the two materials and this intrinsic adhesion, in turn, is a critical component of the measured adhesion which also includes factors related to plastic deformation of the materials. Because virtually all measurements of adhesion include these other factors, accurate values for the intrinsic adhesion have not been available in the past. To develop a means to measure this parameter, nonlinear von Karman plate theory has been used for a consistent analysis of pressurized circular, island and peninsula blister specimens. The configurations considered ranged from linear plates to membranes. Interfacial energy release rates and fracture mode-mixes were extracted. For a given pressure and all possible materials and delamination length to thickness (aspect, a/h) ratios, the peninsula blister provided the highest energy release rate, followed by the island and circular blisters. The extent of yielding in delaminating copper films was greatest with the circular blister. The stress levels in the island blister were notably lower. While extensive yielding was still present in peninsula blister configurations with a/h = 100 and 500, there was none for a/h = 10. A scheme for extending the utility of blister specimens to higher aspect ratios was developed and analyzed. Approved for public release, Distribution unlimited. Reproduction in whole or in part is permitted for any purpose of the United States Government.