Minimizing Warpage of PDMS Mold by Use of a Silicon Backplate in Micro-Molding Process

This paper reports a novel silicon-backed PDMS mold (Si-PDMS mold) designed to mitigate the warpage and deformation commonly observed in conventional PDMS molds during thermal processing. A two-step molding process was developed to fabricate polyimide microneedle array samples using the Si-PDMS mold. Simulation and experimental results show that the silicon backplate can provide rigid support for the PDMS mold, effectively enhancing its structural stability. Compared to PDMS molds, Si-PDMS mold reduces thermally induced warpage from 3.37 mm to 0.19 mm, thereby improving compatibility with patterning techniques such as spin-coating and exposure. The integration of micro-molding and patterning processes allows further patterning to be applied to the backside of the micro-molded samples, achieving higher precision in fabrication.