Technical Library | 2016-11-03 17:53:56.0
We present a novel method for fabricating a high-density carbon nanotube microelectrode array (MEA) chip. Vertically aligned carbon nanotubes (VACNTs) were synthesized by microwave plasma-enhanced chemical vapor deposition and thermal chemical vapor deposition. The device was characterized using electrochemical experiments such as cyclic voltammetry, impedance spectroscopy and potential transient measurements. Through-silicon vias (TSVs) were fabricated and partially filled with polycrystalline silicon to allow electrical connection from the high-density electrodes to a stimulator microchip.In response to the demand for higher resolution implants, we have developed a unique process to obtain a high-density electrode array by making the microelectrodes smaller in size and designing new ways of routing the electrodes to current sources.
Technical Library | 2020-11-04 17:57:41.0
Residues present on circuit boards can cause leakage currents if not controlled and monitored. How "Clean is Clean" is neither easy nor cheap to determine. Most OEMs use analytical methods to assess the risk of harmful residues. The levels that can be associated with clean or dirty are typically determined based on the exposed environment where the part will be deployed. What is acceptably clean for one segment of the industry may be unacceptable for more demanding segments. As circuit assemblies increase in density, understanding cleanliness data becomes more challenging. The risk of premature failure or improper function is typically site specific. The problem is that most do not know how to measure or define cleanliness nor can they recognize process problems related to residues. A new site specific method has been designed to run performance qualifications on boards built with specific soldering materials, reflow settings and cleaning methods. High impedance measurements are performed on break off coupons designed with components geometries used to build the assembly. The test method provides a gauge of potential contamination sources coming from the assembly process that can contribute to electrochemical migration.
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