Au/Cu system is widely used in the semiconductor industries and many other felds(including micro-electromechanical systems,MEMS)[1].As an electronic component,it is applied in the spacecrafts and works in the low earth orbit(LEO)environment,so it is invariably infuenced by UV radiation.The energy of UV photoelectron is strong enough to destroy the chemical structure in multilayer flms of components.Until now there are no reports about chemical structure analysis of surface and interface of multilayer metal flms under UV radiation and scientifc judgment for their failure mechanism.Therefore it is of essential importance to improve or develope the new multilayer thin flms to establish a suitable estimation method to perform early diagnose of the changes on interface structure in electrode flms.The experimental results indicated that the electron migration induced by UV radiation in vacuum was the main reason resulting in the directed diffusion of Cu atoms to surface layer from the Au/Cu interface,the damage of the originally designed interface chemical structure and the fnal failure of the components.At the same time,the thermal effect induced the morphology change of the flms surface,that provided the passage for Cu atoms diffusion to surface layer through crystal boundary of Au layer.In the steady stage under UV radiation,the concentration gradients dCCu/dz of Cu atoms linear decreased with the treatment time t.