Development and experimental validation of an analytical model to predict the demoulding force in hot embossing

Abstract

During the demoulding stage of the hot embossing process, the force required to separate a polymer part from the mould should be minimized to avoid the generation of structural defects for the produced micro structures. However, the demoulding force is dependent on a number of process factors, which include the material properties, the demoulding temperature, the polymer pressure history and the design of the mould structures. In particular, these factors affect the chemical, physical and mechanical interactions between a polymer and the replication master during demoulding. The focus of the reported research is on the development and validation of an analytical model that takes into account the adhesion, friction and deformation phenomena to predict the required demoulding force in hot embossing under different processing conditions. The results indicate that the model predictions agree well with the experimental data obtained and confirm that the design of the mould affects the resulting demoulding force. In addition, the applied embossing load was observed to have a significant effect on demoulding. More specifically, the increase in pressure within the polymer raises the adhesion force while it also reduces the friction force due to the decrease in the thermal stress.