When you are looking for a material for your tungsten probes, it is important that you find one that has a high conductivity. This means that you can make your etching processes more efficient. The material should also be corrosion resistant.
Etching with NaOH
An electrochemical etching apparatus is used to remove
tungsten rods and tips by immersing them in an aqueous solution of NaOH. The
aqueous solution of NaOH is corrosive and may cause chemical burns if in
contact with skin, respiratory tract or other materials. To prevent the
occurrence of chemical burns, proper clothing and protective eyewear are
necessary.
The etchant is introduced into a Teflon-made container. Two
or four tips attached to a holder are dipped into the solution. A micrometer is
then used to measure the diameter of the tip. Etching is carried out at 70 +- 1
degC.
A NaOH aqueous solution of concentration 0.5 mol/L was used
as an electrolyte. The effectiveness of the electrolyte in removing material
from the surface of tungsten was examined. It is a relatively cheap etchant. The
effects of the electrolyte concentration, the interelectrode gap width and the
etching duration were investigated. The effects of the etchant were compared to
those of a conventional concentrated acid electrolyte.
Etching with KOH
The KOH etching technique is widely used in semiconductor
fabrication facilities because of its excellent repeatability and cost
effectiveness. This method is also applicable to the electrochemical
fabrication of nanoscale tungsten probes. It provides the opportunity to study
the influence of ionic diffusion and surface tension on the tip contour.
Electrochemical etching has important implications for
microanalysis, biotechnology, and micro-electronics. The etching process can be
improved by combining experimental and dynamic simulation techniques. By
incorporating these techniques, a tungsten probe can be fabricated with a
smooth, ultra-sharp apex.
In order to etch a tungsten probe, a thin tungsten wire is
immersed in a potassium hydroxide solution. During etching, the electric field
drives ions toward the electrodes. As a result, the electric field also
affecting the ionic distribution along the tungsten wire.
Tungsten probes are versatile tools for atomic scale research and can be
used in biological systems. They are also suitable for electric field emission
systems. Despite their advantages, they are still subject to roughness and
destabilization of their surface due to irregular ionic concentration
distribution.
Etching with rhenium
The invention relates to a method of manufacturing a probe
pin by etching with rhenium on tungsten probes. In addition, it relates to an
inspection device with such a probe pin. A probe pin is an element that is
inserted into an IC terminal. As contact between the IC and the probe is made,
it deforms and causes a change in the contact resistance. It can be used for stable
inspection. An etching process can be employed to create a pin with a convex
taper. This will increase the number of contacts per unit area.
A typical rhenium tungsten wire has a diameter of 30 mm. An
etching process is employed to make the tungsten wire into a probe pin with a
targeted shape. To do this, the rhenium tungsten wire is first plated.
After the etching process, the rhenium tungsten is
straightened. The resulting shape is documented. At the same time, the surface
defects are removed. The rhenium tungsten is then subjected to the wire drawing
process. Once the desired diameter of the rhenium tungsten is reached, it is
heated to a temperature of about 1500 deg C.
Isolated 3-wire sensors
Isolated 3-wire tungsten probes combine a rigid body with a thin Tungsten wire. These probes
are used in a variety of medical applications. They are also found in
radiology, electrosurgery, and fluoroscopy.
The mechanical strength of a probe must be sufficient to
withstand compression forces during insertion and retraction. This is important
to prevent long-term damage to brain tissue. To improve the sensitivity and
durability of the probes, biocompatibility is an important consideration. A
natural immune response could deteriorate the probe's characteristics.
For the most part, these probes are manufactured in a single
step. During fabrication, the entire structure is patterned to provide access
to recording sites. Interconnect traces are then deposited to connect these
sites to bonding pads.
A photo of a three-dimensional neuroelectronic interface is
shown in Figure 1. It shows 1024 recording sites, a LCD monitor, and a camera. Silicon
micromachining has enabled miniaturized neural probes. Moreover, these sensors
have gained attention for their flexibility and biocompatibility.