Conductibility and Adhesiveness
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To guarantee the conductibility and adhesiveness of sensors for implants, e.g. for sensors made of polyamide 6 with a fiberglass piece and a head crafted out of galvanized nickel-gold with a razor-thin layer (3–4 μm) of bond gold, they are treated with plasma at Diener electronic in a class 8 cleanroom. The advantage of low-pressure plasmas consists in the fact that the treated items warm up only slightly. When activating synthetic materials made of polypropylene, the heating is hardly even measureable. The Tetra 50 system is equipped with a rotary drum that has holes in it. The parts are put into this rotary drum as loose material. The rotational motion ensures that the parts are treated equally on all sides.
During plasma treatment energy is continuously fed to the material, its temperature increases, and it converts from a solid, to a liquid and then into a gas. If the energy continues to flow, the existing atomic shells break up and this results in charged particles, i.e. negatively charged electrons and positively charged ions. This mixture is called plasma. A vacuum and a pressure of around 0.4 mbar are also generated in the chamber of the machine. Then process gas enters and a voltage of 40 kHz is generated on the electrodes. This is how the gas ionizes and a plasma results. The plasma removes organic layers from the sensors during treatment. These are attacked chemically by the oxygen used as process gas. The impurities partially evaporate from the vacuum and from the heat on the surface. The energy-rich particles transform the impurities into smaller, stable molecules and then they can be extracted. To guarantee complete traceability, all part-packages are labeled. Based on the information printed there, what charge is involved or when it was produced can be retraced — and the appropriate protocol can be assigned to it without any ambiguity.