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Present day low power electrical contacts systems are based on the heavy use of costly gold coatings. The multi-layered contact systems are typically made on a substrate with a layer of Nickel followed by a layer of Gold with thickness depending on the application and exposure conditions. Main issues with the reliability of electrical contacts are the corrosion and wear, which limits the freedom to reduce the gold layer thickness. The goal of the HIPEC project is to develop electrical contact systems without the use of gold, while providing good corrosion and tribological performance. HIPEC project developed detailed understanding on the corrosion reliability issues of the present day gold coated contacts, including the involved failure mechanisms. Wrok addressed the issues with materials combinations including substrate material and coating as well as the loss of electrical contact due to fretting corrosion. Specail focus was on the contacts used for hearing aids applications.Following this HIPEC project focussed developing new contact systems without the use of Gold, while using an Ni-Sn based under layer with higher passivity followed by a hard, wear resistant layer of conducting coating synthesized by PVD based processes. The aim of the new contact material combination was toprovide greater freedom for substrate choice together with building high performance contacts with necessary electrical properties without the use of gold.
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Important Publications:
V.C. Gudla, R. Ambat, “Corrosion failure analysis of hearing aid battery-spring contacts, Engineering Failure Analysis”, Engineering failure analysis, 79 (2017) 980-987.
Corrosion Reliability of Low Power Electrical Contacts, Abhijeet Yadav (Technical University of Denmark, Lyngby, Denmark) / Visweswara Chakravarthy Gudla (Technical University of Denmark, Lyngby, Denmark) / Rajan Ambat (Technical University of Denmark, Lyngby, Denmark), Eurocorr Praque 2017. |