Enhanced interfacial mechanical properties by micro-nano structures via self-assembly mask etching

Heterogeneous composite materials are widely used in microelectronic, optoelectronic, and flexible devices, yet their reliability is often limited by insufficient interfacial bonding strength and thermal mismatch–induced failure.Here, a generally applicable interfacial enhancement strategy based on microsphere self-assembly mask etching is proposed, in which ordered micro–nano structure arrays are constructed on substrate surfaces to simultaneously improve interfacial mechanical properties and thermal stability.By combining periodic microsphere self-assembled masks with dry etching, structurally consistent micro–nano architectures can be rapidly fabricated on both inorganic and polymer substrates without high-temperature processing.Representative systems including Cu/SiO₂, Cu/poly(methyl methacrylate) (PMMA), and indium tin oxide (ITO)/PMMA are systematically investigated using nano-scratch, micro-scratch, pull-off, and thermal shock tests.The results show that the micro–nano structures significantly enhance interfacial bonding by increasing the effective contact area and inducing strong mechanical interlocking.For the Cu/SiO₂ system, nanoscale Cu coatings remain intact without delamination under an 80 mN load, while the critical failure load of microscale coatings increases from 6.53 N to 16.62 N.In the Cu/PMMA system, nano-scratch tests reveal an increase in interfacial failure load from 5.53 mN to 45.05 mN, accompanied by a transition from interfacial delamination to coupled coating damage and substrate structural collapse, and the pull-off bonding strength of microscale coatings is further improved by ~49%.Moreover, the micro–nano structures effectively suppress cracking and wrinkling of ITO coatings on PMMA under thermal shock conditions up to 80 °C.This work provides a simple, low-damage, and broadly applicable route for strengthening heterogeneous interfaces and improving thermal reliability in advanced electronic and flexible systems.