Conductive PEEK Film
Researchers at the Universities of Queensland und New South Wales in Australia have succeeded in increasing the electrical conductivity of PEEK film considerably by means of ion implantation. Ion implantation is used to incorporate foreign atoms into a substrate in order to modify the material properties of the substrate.
The process is used primarily in conjunction with silicon-based semiconductors, Experiments with polymer-based materials showed only little success in the past. The group of researchers succeeded in increasing the electrical conductivity of PEEK by applying a thin layer of zinc to the surface of the PEEK film and subsequently irradiating it with a beam of zinc ions. During the irradiation, three different effects occur.
The first effect is that zinc atoms are ejected from the metal coating, reducing the amount of metal on the surface. The second effect is that zinc atoms are transported from the surface into the interior of the polymer film by the ion beam. There, they form a conductive region that is better protected from environmental factors such as moisture and air than is the metal coating on the surface. In a certain sense, this process can be considered similar to tattooing, states the institute. In that case, ink that can be washed off the surface of the skin easily is embedded in deeper layers of the skin, where it is protected permanently. The third effect of the ion beam is that chemical bonds in the polymer are broken, and oxygen, nitrogen as well as hydrogen are released. As a consequence, the carbon content increases, increasing the conductivity further.
As an example of an application, the team of researchers produced an electric resistance thermometer from the conductive PEEK film. The thermometer’s accuracy was just as high as or even higher than that of commonly used platinum or ceramic resistance thermometers. The Australian researchers find particular value in the fact that the conductivity of the material can be adjusted very accurately by means of certain process parameters. The conductive PEEK film can be produced on equipment typically found in the semiconductor industry and is considerably more resistant to oxygen than other conductive polymers.
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