Abstract: The defects caused by auto/manual demolding are studied to get better imprint quality in micro hot embossing process. Finite element method (FEM) is used to simulate the demolding process of high aspect ratio microstructures. The results show that the stress concentration mainly occurs at the bottom of microstructures when the auto demolding device is used. The maximum demolding stress is generated during the initial stage and the defects are mainly necking and root fracture. Great stress concentration will be caused by concentration little demolding direction deviation in manual demolding, and that stress concentration will reach the maximum in the late stage of the demolding process. 190 MPa stress can be caused due to 5° direction deviation, then the demolding defects are mainly microstracture topping and root fracture. So an auto demolding device is needed when fabricating high aspect ratio structures. A new pneumatic demolding device is designed to overcome the warp distortion of polymer substrate caused by the traditional demolding system. Successful fabricating of microstructures with an aspect ratio of 3.3 verifies the improvement of the demolding device.

Key words: Demolding stress, Finite element method, Hot embossing, Polymer