Theoretical model for ablation of thick aluminum film on polyimide substrate by laser etching

The ablation mechanism of thick aluminum film on polyimide by a 1064 nm Nd:YAG laser etching was investigated. By establishing a theoretical model based on interaction of laser and material, the effects of laser parameters including laser power, equivalent laser pulse number, and scanning velocity of laser beam were studied. The results show that when a laser beam with fluence higher than the etching threshold of aluminum irradiated onto the target surface, the etched depth for a single laser pulse is a definite value; the equivalent laser pulse number can be derived when a polyimide plate coated with aluminum film was selected as an object of study. Namely, an optimized etched result can be obtained which corresponds to certain laser fluences and beam scanning velocities. By substituting the calculated results of laser processing parameters into a finite element simulation, the etched results of aluminum film on polyimide could be achieved. The simulated and experimental results present a good coincidence, and the results can be used to set practical laser processing parameters.