Characterization of the micro injection-compression molding process for the replication of high aspect ratio micro-structured surfaces

The complete and uniform replication of micro-structured functional surfaces is still challenging, even using state-of-the-art micro injection molding technologies, thus hindering the development of new optical and bio-medical applications. Injection-compression molding is a candidate process to overcome the inherent limitations of conventional injection molding by evening the polymer pressure inside the cavity. However, injection-compression molding is characterized by a more complex process control, especially when a rapid heat cycle molding is adopted. In this work, the applicability of variothermal injection-compression molding for the manufacturing of high aspect ratio micro-structured surfaces was experimentally investigated. To achieve the required replication accuracy the study and the optimization of process parameters were carried out, considering the factors that control the compression phase, which pushes the hesitating polymer into micro features. The results show how the optimization of process parameters that are related to the compression phase can be effective to improve and level the replication of high aspect ratio micro features. Moreover, the critical issues arising from the selection of very high mold temperature were investigated, controlling the breakage of the replicated micro features inside the mold.