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>>