Numerical simulation of micro hot embossing of polymer substrate

Micro hot embossing, one of the important steps in the LIGA process is aimed at increasing the scale of production. The process involves: molding-in which metallic mold is pressed into the polymer, cooling-in which mold and the polymer are held together and demolding — where in the mold is separated from the polymer. In the past, these steps in a micro hot embossing process are modelled independently. As the parameters in each of these stages influence the final product quality, the simulations were performed using DEFORM 3D and by transferring the strain history from one stage to another. The final product quality thus is a function of the preceding quality in each stage. The parametric analysis shows that, at lower level of molding speed (0.01 mm/min–0.1 mm/min) and lower level of molding temperature (105°C–115°C), complete mold filling was evident. In the cooling stage, the difference between the molding and demolding temperature governs contact stresses and thermal shrinkage. At the same time, in the demolding stage, lower rate of demolding ensures lower residual stresses in the micro components formed. Experimental validation of the results shows that the predicted results agree fairly with the simulated values.