Hot embossing precise structure onto plastic plates by ultrasonic vibration

Abstract

Hot embossing achieves excellent performance in replicating precise features onto large plastic plates. It has become a popular approach because microstructures in master molds can now be easily made using Lithographie GaVanoformung Abformung (LIGA) and micro-electro-mechanical-system (MEMS) technologies. However, there are still some unsolved problems that confound the overall success of this technology. Long cycle times caused by conventional electric or hot oil heating is one of them. This research attempted to use ultrasonic vibration as a heat generator for hot embossing. The first part of this study investigated the replication capacity of ultrasonic-heating embossing of both amorphous and semicrystalline plastic plates; the second part of this study examined the effects of various ultrasonic vibration parameters on the contour of replicated structure; and the third part of this study identified the relative significance of all these parameters on molded part quality. In addition, the temperature profiles at different depths of the embossed plates by ultrasonic vibration were measured. The experimental results in this study suggest that ultrasonic vibrated hot embossing could provide an effective way of molding precise structure onto polymeric plates. This would provide significant advantages in terms of a shorter cycle time as well as improved product quality. POLYM. ENG. SCI., 45:915–925, 2005. © 2005 Society of Plastics Engineers