Research and Development of the Micro-Embossing of Polymeric Photonic Parts

This research is to develop various techniques for micro-embossing of polymeric photonic parts. The techniques investigated will include ultrasonic vibration embossing, IR heating embossing and soft mold roller embossing. The proposal will include a three-stage research and will be competed in three years. For the research of the first year, the study will attempt to use ultrasonic vibration as a heat generator for hot embossing. Both amorphous and semi-crystalline polymers will be evaluated in this study. The amorphous polymers will be polymethylmethacrylate (PMMA) and polyvinyl chloride, and the semi-crystalline polymers will be polyethylene and polypropylene. A 2000-Watt Mecasonic model Omega-2 ultrasonic welder will be used for all the experiments. The output frequency of the machine is 20 kHz. During vibration hot embossing, the microprocessor-controlled machine is used to record vibration time, embossing time, embossing pressure, power and energy. The replication capacity of ultrasonic-heating embossing will be studied. The second part of this proposal will focus on the replication of microstructure by IR heated embossing. An IR heating hot embossing facility will be designed and built in our lab. The system will include an IR heating device, a pneumatically actuated press and a control circuit. The quality of replicated parts will be examined. The temperature distribution of embossed plates will be measured. The effects of various IR embossing parameters on the contour of replicated structure and the relative significance of all these parameters on molded part quality will be investigated. In the third year, a soft-mold roller embossing facility with UV exposure capacity will be designed, constructed and tested in this research. To fabricate the soft mold with an array of micro-block cavities, a silicon mold with a micro-cavity array will be first fabricated by photolithography and deep reactive ion etching. A polycarbonate film will be gas pressurized hot embossed against the silicon mold to obtain a master of micro blocks. The soft mold for the roller stamp will be obtained by casting the polydimethylsiloxane over the polycarbonate master to obtain an array of micro block cavities. During rolling operation, a step motor will drive the roller and press the UV-curable photopolymer layer on the glass substrate through the rolling zone. A micro-block array will be obtained. At the same time, the micro-block array will be cured by the UV light radiation while traveling through the rolling zone. The effect of various processing parameters on the replicability of the micro-blocks will be investigated. The final goal of this research is to develop various molding techniques for the micro-embossing of photonic parts. This will provide significant advantages in terms of reduced cycle time as well as improved products quality.

Project ID:PB9706-1806
External Project ID:NSC96-2628-E182-001-MY3