Micro powder blasting

The depth of structure achieved will depend on the processing time. The aspect ratio is 2-3, and the smallest structure that can be created is 50 pm. The masks are created with photolithography. The process permits both very fine tolerances of shape and position and also allows as many lateral structures/side by side as desired, densely packed. The mechanical nature of the procedure means that the chemical composition of the material is unimportant. As the items are not exposed to heat, there is no distortion. One disadvantage is the angle of the abraded contours to the surface of the substrate. It will be 70° to 85°, depending on the depth sought. Deeper 

The ideal process can be selected for a particular application if one knows the nature of various procedures. It is also possible to combine procedures. 

The difficulties of processing glass have already been described. The following are the other technologically significant methods. 

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Microabrasion using compressed air is a modification based on sand blasting, the micro powder blasting. This process enables all types of glass, ceramics, and semiconductor materials, whatever their chemical composition and crystal structure to be inexpensively processed down to the micrometer scale. The micro powder blasting is a masked procedure it works quasi parallel on the whole substrate. A powder jet drives systematically, over the substrate. Material is removed at the mask openings (Figure 3.17). 

Wensink, H., Elwenspoek, M.C., New developments in bulk micromachining by powder blasting. Micro Total Analysis Systems, Proceedings 5th p7AS Symposium, Monterey, CA, Oct. 21-25, 2001. Kluwer Academic Publishers, Dordrecht, the Netherlands, 2001, 393-394. 

Wensink, H., Berenschot, J.W., Jansen, H. V., and Elwenspoek, M.C. (2000) High resolution powder blast micromachining. Micro Bectro Mechanical Systems, 2000. MEMS 2000. The Thirteenth Annual International Conference on. pp. 160-77A. 

Amino-aldehyde resin blasting compn containing gaseous w>ids. An example is thiourea 10, sodium nitrate 10, AN 30, powdered Al 2Yt, 377o aq formaldehyde 10 parts, adjusted to sp gr 1.17 with glass micro-spheres)... 

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