Anomalous debonding behavior of a polymer/inorganic interface

Adhesion and subcritical debonding at the interface between a thin diglycidyl ether of bisphenol F polymer layer and either SiNx or SiO2 passivated silicon substrates are described. The interface is characterized by weak hydrogen bonding. Prolonged exposure to a moist environment resulted in a time-dependent decrease in adhesion. Subcritical debond-growth rates as a function of applied loads were sensitive to temperature and relative humidity, and greatly accelerated in the presence of cyclic loading. Of particular interest was the occurrence of an anomalous region of persistent debonding that developed below similar to 10(-8) m s(-1) under both monotonic and cyclic loading. In this region, debond-growth rates were characterized by a weak dependence on the applied loads, a strong dependence on moisture activity, and the absence of a measurable threshold below which debonding could not be measured. We propose a new stress-dependent transport model that describes the moisture diffusion mechanism responsible for this anomalous behavior. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.