Surface features of polymer and ceramic microstructured parts manufactured by micro injection molding

Microstructures are produced respectively by polymer and powder micro injection molding under different process conditions. Two different types of mold insert are designed and manufactured by ICP etching: one with exhaust passage and the other with micro blind hole. This paper investigates the effects of injection parameters, mold vacuum, and silicon mold on the surface quality of polymer microstructures and ceramic green parts. The effects of powder content and sinter temperature on the surface roughness of ZrO₂ microstructures are also studied Investigation indicates that inappropriate injection conditions will induce rough and cured surface with cavity. The surface quality of micro structures will improve obviously if the mold is vacuumed before the injection stage. The roughness of etched silicon mold surface is about 0.31 mum. These completely filled polymer microstructures and ZrO₂ green parts have approximately same roughness with the silicon mold. If microcavities were filled completely, the effects of injection pressure, mold temperature and holding time on the surface roughness of polymer and ceramic green microstructures is not obvious. Sub-micron ZrO₂ powder could improve the surface roughness of sintered ceramic microstructures.