Evaluation of film adhesion strength on textured surface: experiments and mechanisms

The durability and reliability of thin films are largely governed by their adhesion strength, which plays a pivotal role in advanced applications such as thermal barriers for aero-engines, conformal devices for flexible electronics, and packaging layer for integrated circuits. Despite its importance, traditional adhesion strength enhancement strategies mainly depend on trial-and-error or consider a limited number of factors under specific conditions, falling far from a general predictive model that integrates multiple factors. To rapidly and accurately identify the optimal film parameters for high adhesion strength on various substrates, in this work, we developed a normalized index that integrates surface energy, mechanical blocking and interlocking, and the effects of components on adhesion strength. Each factor is modularized and can be selectively evaluated based on specific requirements; for example, chemically inert ceramic substrates do not require consideration of component variation effects, whereas metal substrates do. Following experimental and literature-based validation, the normalized index demonstrates good predictive capability for the adhesion strength of thin films on ceramic, metal, and carbon fiber-reinforced polymer substrates. This advancement could greatly enhance the performance and lifespan of advanced technologies, providing a promising path for future thin film applications.