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Micro Machining
Fabrication of Microelectrode Arrays With Micro Wire Electrical Discharge Machining
High electrode count neural interfaces are an essential tool in understanding and learning about the central and peripheral nervous system of animals and humans. Monolithically fabricated devices from silicon thus far were limited to electrode lengths of around 1.5 mm. This limits the area of cortical sulci to be interfaced with.
Using micro wire electrical discharge machining (micro-WEDM), the electrodes with lengths of up to 9 mm were machined successfully. A method of etching to remove the recast layer was also investigated.
A PZT Driven Micromachining Tool Based On Single-Point Tool Tip Geometry
This novel micromachining technology is based on single-point diamond tip milling which can be used to machine microsized features into a wide range of materials ranging from polymers, through metals to glass. The unique characteristic of this technology is that the cutting velocity is not created by rotating the tool tip about its axis of rotation. Instead, the cutting motion is generated by actuating the tool tip on a recirculating, microscopic trajectory at high frequencies. This allows a standard 3-axis setup to generate the macroscopic motion required for the tool path while at the microscopic level, the cutting motion and the tool path are being generated by the tool itself. As a result, truly three-dimensional part geometries at the micron level with exceptional surface finish and part accuracy can be created. more>>
Shaping And Slicing Of Germanium Boules Using Wire-Electron Discharge Machining (EDM) For Reduced Subsurface Damage And Increased Productivity
This project seeks to create innovation resulting in the potential use of wire-EDM in the shaping of germanium boules and its subsequent slicing into wafers. This method promises the potential of decreased subsurface damage at the edge of the wafers, which is thought to be the leading cause for wafer breakage during handling and a principal cause of latent defects in the orbiting solar cell applications. A second benefit of the proposed machining process is the potential for better flatness of the wafers, which allows the wafers to be cut thinner compared to conventional methods, while simultaneously reducing the amount of material to be removed to achieve the required flatness. A third advantage of wire-EDM is the fact that the wire used in the process (25-50 μm diameter) is significantly thinner than the diamond-coated wire currently in use (150 μm). This allows considerably more wafers to be cut from s single boule, thereby increasing the production yield and decreasing manufacturing cost. Using wire-EDM to shape the boule and slice the wafers has a fourth, potentially very beneficial aspect: Most excess material removed is in the form of large pieces which have a better potential for recoverability compared to the dust that is produced with conventional, abrasive machining processes. If performed economically, this "green" process will reduce waste and further reduce manufacturing cost. more>>
Flexural Micro-EDM Head For Increased Productivity of Micro-Holes
The drilling of micro holes ranging in diameter from 8 - 500 microns without any burrs and free of tapers is largely the domain of micro-electro discharge machining (EDM) and more recently micro-electro chemical machining (ECM). Typically, these holes are drilled using a matched electrode with a diameter that is slightly smaller than the hole to be drilled. The difference in diameter is determined by the amount of overcut that occurs during machining, typically a few microns. The matched electrode, while capable of creating very small holes, poses a number of problems. Obviously, every hole size needs its own electrode, making this technique tooling intensive. A second challenge is the supply of the dielectric fluid. For larger sized holes, a hollow electrode can be used to supply the fluid to the bottom of the hole. For very small holes, this proves to be very difficult. more>>
