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A coupling model to simulate the dynamic process of blister-actuated nanosecond laser-induced forward transfer

The modeling of laser-induced forward transfer process (LIFT) is helpful to understand and optimize its complex transfer process. In this work, a coupling model is developed to investigate the dynamic response of a thin polymer layer used as the release layer in the blister-actuated LIFT. In this model, the vapor pressure generated by nanosecond laser irradiation is computed through coupling with the transient vapor volume obtained from different step durations to simulate the dynamic blister formation. And the model is validated by experiments on polyimide film irradiated with different laser fluences, which is found to be capable of providing a consistent prediction of blister profiles under several laser conditions. The calibrated energy conversion ratios imply that laser pulse energy is mainly allocated for the heating and vaporizing of polymers, but increasing laser fluence can make this expense gradually saturated to allow more pulse energy to increase the vapor pressure. Transient pressure development from the coupling model is observed to increase rapidly within the pulse duration, but then to decrease because of vapor expansion. Forward velocity in axial direction is also observed to increase with laser fluence. The maximum velocity is possible to exceed the sound velocity under a high laser fluence. And the thin polymer layer is more preferred to obtain a high transfer velocity.