Comparison of height replication properties of micro-injection moulding and micro-injection compression moulding for production of microstructures on lightguiding plates

An analysis of the effect of process parameters on the height replication of microstructures on lightguiding plates produced by micro-injection moulding (MIM) and micro-injection-compression moulding (MICM) is presented. The plates, of the size employed for LCD displays on digital cameras, feature microstructures with a radius from 100 to 300 mm, increasing linearly from the thin to the thick end of the plate. A single-parameter method was employed. For MIM, the most important process parameter for replication was found to be mould temperature, followed by packing pressure and melt temperature; and for MICM, mould temperature, followed by compression distance and melt temperature. Mould temperature is clearly the most significant factor for both processes. Height replication was found to be better for MICM than for MIM.