Spatial gas effect on the deformation behavior of embossed glass microstructures in hot embossing

Glass hot embossing is a well-established and cost-effective manufacturing method for glass microstructures. However, the spatial volume affects deformation behaviors in closed mold cavities, which determines the final shape of the embossed glass. To investigate the spatial gas effect on the glass deformation mechanism during hot embossing, we used the focused ion beam (FIB) to fabricate blind micro-hole array structures with different depths as embossing templates. The experimental results demonstrated that the spatial volume of the mold cavity has a great influence on the energy of gas expansion, thus affecting the deformation height of glass microstructures during hot embossing. The deeper the cavity depth, the bigger the surface tension, resulting in larger surface concave deformation. Due to the surface tension of gas expansion, the deformation height of the edge zone is higher than that of the center zone at a higher embossing temperature until the heated glass is completely compressed into the mold cavity. Additionally, at lower embossing temperatures (520 °C), the heated glass has a large deformation resistance and elastic recovery. The more deformation volume escape from the shallower mold cavity because of the spatial effect, thus the deformation height decreases as the cavity depth reduces. The work provides a better understanding of manufacturing glass microstructures in hot embossing.