High aspect ratio microfeatures

Yao D, Kim B (2002) Injection molding high aspect ratio microfeatures. J Inject Molding Technol 6 11-17... 

However, high aspect ratio three-dimensional (3D) microfeatures are required in various microengineering applications. These can be machined by 3D EMM. Very hard, noncorrosive, and electrically conductive materials are suitable for microtools, such as tungsten, tungsten carbide, and... 

Microdevices fabrication for MEMS and other microengineering applications have been reported in Chapter 10. It presents a clear view on fabrication of microfeature of aluminum, copper, stainless steel, nickel, and titanium, etc., for MEMS. Some of the interesting topics included in this chapter are fabrication of high aspect ratio features for MEMS as well as micromachining of semiconductor by EMM. Here, EMM has successfully demonstrated its capabifity as an alternative technique for machining of microdevices with three-dimensional features of higher resolutions on metals as well as semiconductors. 

Precise replication of microfeatures and nanoscale features, especially high aspect ratios... 

In the final step, the embossed substrate is cooled to a temperature below the Tg, where the plastic material transitions back to the rigid state. After reaching this lower cycle temperature, the embossing master is mechanically separated from the polymer substrate that now contains the desired microfeatures. Separation is a critical step due to the large forces that act on the polymer structure and mold. This is particularly tme for microstructures with vertical sidewalls and high aspect ratios. The overall cycle time of the embossing process is typically 1-10 min. 

---