Micromechanical machining

TES are based on the steep temperature dependence of the resistance of superconducting metallic films. The useful temperature range is very narrow. These thermometers which may have a very low intrinsic noise, are fabricated by a vacuum deposition process at very low pressure and are patterned either by photolithography technique (see e.g. ref. [21]) or by micromechanical machining (see e.g. ref. [22]). The dimensionless parameter a = T/R-dR/dT defines the DC quality of a sensor. TES with a as high as 1000 have been built [23],... 

A new concept in the field of sutures is the development of barbed material, which is a monofilament product that has micromechanically machined barbs on the surface. The presence of barbs, which are either mono- or bidirectionally oriented, allows sutures to be held in tissues without a... 

Packaging (paper and plastic) packaging adhesives release coatings barrier coatings Photochemical machining (89) micromechanical parts optical waveguides... 

The majority of micromechanical devices require 3D machining of the bulk silicon material with etching depths of up to wafer thickness. Generally, three basic etching process types can be distinguished ... 

Figure 6.5 Example of SACE glass gravity-feed drilling with a 0.4 mm stainless steel tool-cathode at 31 V in the case of high inter-electrode resistance. In situation (a) the gas film needs to be built up more often than in situation (b). This results in an overall slower machining for situation (a) than situation (b). Reprinted from [130] with the permission of the Journal of Micromechanics and Microengineering.

Figure 6.10 Evolution of SACE glass gravity-feed drilling in the machining voltage-drilling depth plane. Reprinted from [84] with the permission of the Journal of Micromechanics and Microengineering.

Figure 6.12 Different types of channels in 2D-SACE machining. Machined using a 0.2 mm cylindrical stainless steel tool-cathode in 30 wt% NaOH (a) well-defined linear channel edges and smooth channel surface (b) jagged outline contours with smooth channel surface (c) heat affected edges with smooth channel surface (d) heat affected edges with rough channel surface (e) deteriorated microchannels. Reprinted from [23] with the permission of the Journal of Micromechanics and Microengineering.

T.F. Didar, A. Dolatabadi, R. Wiithrich Characterization and modeling of 2D-glass micro-machining by spark-assisted chemical engraving (SACE) with constant velocity. Journal of Micromechanics and Microengineering 18 (2008). 

Laser Beam Machining, Fig. 6 Micromechanical components with moveable parts generated by laser-based layer manufacturing (microstereolidiography)... 

Crary, S.B., G.K. Ananthasuresh, and S. Kota. 1992. Prospects for microflight using micromechanisms. Pp. 273-276 in Proceedings of the International Symposium on Theory of Machines and Mechanisms, International Federation of Theory of Machines and Mechanisms-Japan Council, Nagoya, Japan, September 24-26, 1992. 

In conventional-sized machines such as an engine systan, lubricants are often used to reduce the friction force. Liquid lubricants, however, generate capillary force and often cause stiction in micranechanisms. Moreover, even a low-viscosity liquid tends to increase friction force because viscosity drastically iuCTeases when the spacing between solid surfaces becomes narrow and is on the order of nanometers [8]. Therefore, liquid lubricants could cause an increase of the friction force in MEMS. In micromechanisms, one solution for reducing the friction force is molecular boundary lubrication. 

MEMS devices need to be separated from the substrate using a wafer dicing machine before they can be packaged. However, unlike IC devices, water used in the dicing operation will destroy micromechanical components. Moreover, DIP technology cannot be used since the molding process will also destroy the micromechanical part of the MEMS devices. 

---