Friction and Wear Behavior of Polymer-Gold Contact Pairs in a Micromechanical Switching Element Under Fretting Load

Micromechanical switches are tiny mechanical devices consisting of movable parts that physically open or close electrical circuits, enabling the control of electrical signals in electronic switching applications. They are used in various applications, including telecommunications, data transmission, signal processing, electrical test and measurement devices, and portable electronics, due to their small size, low power consumption, fast response time, and high reliability. In this investigation, we assessed the tribological performance of polymeric-gold contact pairs within a micromechanical switching element under fretting load. Each contact pair comprises a Cu-Be flat with Ni-electroplating and gold coating, along with a polymer pin, with polyamide-imide (PAI) and polyetheretherketone (PEEK) chosen as the pin materials. We evaluated friction and wear performance using metrics such as the coefficient of friction, wear depth, wear profile, and transfer layer formation, under fretting conditions with a normal load of 25 grams-force. Both polyamide-imide (PAI) and polyetheretherketone (PEEK) polymer pins exhibited abrasion wear, with PAI showing stronger adhesion and a more prominent transfer layer on the gold surface compared to PEEK. The wear regions were larger for PEEK-gold pairs. The coefficient of friction (COF) increased initially and then stabilized, with PAI-gold pairs showing a COF range of 0.25-0.4 and PEEK-gold pairs ranging from 0.3-0.4.