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

Abstract

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 °C–50 kgf–200 s for PMMA and 260 °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 1:2.5) and was applied to metallic mold replication. The patterned fields composed of lines of structures in the Ni mold with 25 µm height and 10 µm 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.

Micromachining of Parylene C for bioMEMS

“…Other techniques leveraging the thermoplastic property of Parylene includes a hot‐embossing process, where a nickel mold was pressed into Parylene films at 150°C to form an imprint with <2.32% dimensional deviation (Fig. b) . Thermal forming of Parylene free films has also been demonstrated by annealing multi‐layer Parylene devices with varying thickness or differing Parylene variants (Parylene C and N layers) to create residual stress differences to form self‐curling films .…”

Formation of three-dimensional Parylene C structures via thermoforming

“…Also, these techniques may not be suitable to achieve structures with large aspect ratios, as the Parylene structure is limited by the photolithographic or mold fabrication processes employed. To address these limitations, some studies have focused on leveraging the thermoplastic nature of Parylene to form 3D structures using a hot embossing process [21], as well as a modified polymer bonding technique [22], for both die level [13,23] and wafer level bonding [22,24] to assemble Parylene structures via bonding of a top open structure and a bottom substrate layer. These processes successfully produced microchannel structures while eliminating the need for a sacrificial material.…”

Numerical Study on Thermal Design of a Large-Area Hot Plate with Heating and Cooling Capability for Thermal Nanoimprint Lithography

“…Thermal NIL [20,21] Thermal The following requirements must be considered in the design of TH-NIL hot plates.…”

“…The key to Model II is in modeling the heat pipe. The heat pipe's axial effective thermal conductivity is considered to be around 80 times that of copper [20], and the heat pipe was simply modeled as a solid which has 80 times the thermal conductivity of copper. In cooling mode, the cooling of the 30 mm at the end of the heat pipe was performed at boundary conditions with a convective heat transfer coefficient h_heatpipe of 1768.4 W/m 2 K and an external temperature of 17.2.…”