| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 94 === Polymer micromolding technique are becoming increasingly important in recent years. Compared with other molding technique, hot embossing is favorable for molding microstructures and optical devices because of its low flow rate and low material flow character. However, due to the differences of thermal expansion coefficient between polymer and mold insert, shrinking of polymer in the cooling stage may lead the mold cavities to press the microstructure from both sides. This force will cause the demolding destruction of microstructures and limit the application of molding larger surface areas and higher aspect ratio microstructures on hot embossing technique. Therefore, this study improve the mold insert with rapid heating-function which our laboratory develop and use it to surmount the limit on micro-hot-embossing. We try to use P type silicon wafer as mold insert and implant phosphorous ion into the surface of silicon wafer to make mold insert have heating function. With the heating function, we can decrease the thermal stress of polymer in molding process.
Experiment results demonstrate that the microstructure will produce these defects with creak, slant, damage in the mold insert at demolding when the microstructure by hot embossing has filled with up to 3 times of aspect ratio. Applying appropriate heating power to the surface of mold insert can decrease the thermal stress effectively in the cooling stage to solve the problem of demolding and can improve non-uniform shrinkage of polymer.
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