The phenomenon of irradiation enhanced adhesion of thin films has been studied for the case of 700 Å Cu films deposited on alumina, fused quartz and glass-ceramic. Peel test measurements were made as a function of ion dose from 1014 to 5 × 1016 ions cm2, for both 200 keV He+ ions and 280 keV Ne+ ions. Subsequent heating at 450°C for l h further increased the adhesion of the irradiated interfaces by as much as a factor of 10. The thermal stability of the adhesion was also demonstrated by an interface wetting test. In view of the inability of Cu to reduce these substrates chemically, the strength and stability of the enhanced adhesion are surprising. Some possible explanations are proposed. The ability of both He+ and Ne+ to produce strong bonding indicates that enhanced adhesion can be produced by both nuclear and electronic components of ion energy loss. © 1985.