Precision interface engineering in low-energy electron beam curing: the role of substrate backscattering and depth-dose profiles

Low-energy electron beam (LEEB) curing enables precise surface modification, yet the microscopic energy deposition at heterogeneous interfaces remains poorly understood, often leading to suboptimal interfacial cross-linking or substrate damage. Herein, we establish a mechanism-driven interface engineering strategy by integrating Monte Carlo simulations (FLUKA, 50–250 keV) with experimental validation (up to 200 keV) using a PDMS model system. We elucidate the critical role of secondary particle cascades in determining surface properties and define a universal physical criterion for robust curing: aligning the peak cascade intensity precisely at the coating/substrate interface. Furthermore, we quantify the profound impact of substrate density. High-density substrates (e.g., steel) act as an “energy mirror,” significantly enhancing the localized interfacial dose via backscattering. Conversely, for low-density substrates lacking this effect, we reveal a necessary strategic crossover toward controlled over-penetration to secure sufficient interfacial adhesion. This work moves beyond empirical trial-and-error, providing a framework to balance bulk uniformity against interfacial over-irradiation risks for superior coating performance.