Micro-injection molding with the infrared assisted mold heating system

Mold temperature and packing pressure are the major factors that affect the process of micro-molding. The mold temperature was found to be the crucial factor that controls the success of the complete filling. In micro-injection molding, the mold temperature has to be close to the glass temperature to ensure a good replication of the micro-features. This study is to investigate the effect of infrared mold surface rapid heating system on the micro-injection molding. The micro-feature was defined by the UV lithography technology and transfer to the nickel mold insert by micro-electroforming. An infrared heating system is designed and built to heat the mold surface dynamically. The infrared heating system raises the mold cavity temperature locally to facilitate the replication of the micro-structure. The results show that mold cavity surface must be heated to above a critical temperature before molding. The critical temperature is close to the glass transition temperature and it decreases with the increase of the packing pressure. For mold temperature in 80 °C, heating more than 10 s can result in a complete filling of the micro-feature used in this study.