Combinatorial library designs for quantifying thin film adhesion via the edge delamination test

Abstract

We have demonstrated a combinatorial thin film library design for investigating the adhesion between film and substrate as measured by the edge delamination test. This library design allows rapid screening of critical parameters that control thin film reliability and bond strength in films and coatings. Specifically, our library design was aimed at quantifying the effect of film thickness and composition on the interfacial integrity between the film and underlying substrate by applying thermal stress. To create the combinatorial library, a single specimen was fabricated having a thickness gradient of an epoxy film on glass or silicon substrates. After sectioning the film into individual squares, a temperature gradient was applied orthogonal to the thickness gradient to induce debonding events where the adhesion is below a critical value. In addition, another combinatorial library was carried out using the epoxy films with concentration gradient and constant thickness, and applying a constant temperature. The combined results clearly demonstrate that our combinatorial library design and approach provide a large parameter space for accurately and reproducibly mapping the interfacial integrity and bond strength of film/substrate systems.