Fabrication of a micro patterned parylene-C master by hot-embossing and its application to metallic mold replication

This study demonstrates a replication process for metallic micro mold that combines poly-chloro-p-xylylene (parylene-C) hot-embossing and electroplating techniques. First, the replication characteristics of parylene-C were investigated and compared with those of poly-methyl-methacrylate ( PMMA) in terms of the dimensional accuracy of replication. For a given mold (aspect ratio 1: 1), the complete filling conditions were 150 degrees C-50 kgf-200 s for PMMA and 260 degrees C-200 kgf-900 s for parylene-C, respectively, implying the significantly better durability and heat resistance of parylene-C. The results of surface topological analysis revealed that the dimensional deviation between the mold and the resulting embossed profiles was < 2.94% for PMMA and < 2.32% for parylene-C, indicating that a hot-embossed parylene-C could be an alternative master for electroplating. Then, a micro-patterned parylene-C master was prepared by hot-embossing with a mold (aspect ratio 1 : 2 center dot 5) and was applied to metallic mold replication. The patterned fields composed of lines of structures in the Ni mold with 25 mu m height and 10 mu m width/spacing were successfully replicated on parylene-C with a dimensional deviation of about 1.4%. The electroplated Cu successfully filled parylene-C replica master patterns with an aspect ratio of 2.5 without void formation by both adding organic addictives and controlling the seed layer thickness. After electroplating, the Cu micro mold could be successfully separated from the parylene-C replica master.