In-situ observation on the real-time filling deformation of PMMA into microchannel during hot embossing

Hot embossing is a promising technology for mass production of PMMA microstructures due to its high effi-ciency, low cost, and high replication accuracy. However, the real-time filling deformation behavior of PMMA in hot embossing is rarely reported. In this study, a novel hot embossing equipment with an in-situ observation system is developed. Moreover, a characterization method is proposed to dig up information about the real-time central filling ratio and shape evolution of PMMA in microchannel mold cavity. Initially, a series of hot embossing experiments were conducted to evaluate the effects of process parameters on the replication accuracy of PMMA microstructures. After that, a general pattern of the real-time central filling ratio of PMMA micro-structure in the embossing stage is proposed, where it increases continuously in a decreased rate, and finally reaches a steady-state value. Finally, the real-time shape evolution and average curvature of PMMA micro-structures are studied by using the in-situ observation system. It is worth to mention that the in-situ observation method has the highlights of real-time and intuition, which is quite suitable for investigating macro/micro-scale deformation behavior of materials beyond PMMA.