Corrosion effects on the electrical performance of silver metal contacts

Abstract

In this work, commercial silver metal contacts welded on top of silver plated brass or brass substrates have been exposed to air rich in NaCl. Scanning electron microscopy and energy dispersive analysis of the exposed contact surfaces were performed to identify the corrosion byproducts on top of the silver contacts, suspending wafers, and welding materials. Surface corrosion products were mainly found to consist of small spherules of Cu-Zn or Ag-Cu compounds which cover the surface of the contact proper with low adhesion properties. They mainly originate from the underplating wafer or welding materials. Electrical characterization of the contacting materials was based on dc temperature overheat tests, current switching cycle tests, and energy storage during ac current excitation. The experimental results display that the operating environment is indeed a very significant parameter determining the overall performance of the electrical contacts. New design rules as well as material selection properties may have to be systematically considered to allow for electrochemical induced degradation in saline operating environments.

Sulphur corrosion effect on the electrical performance of silver films elaborated by physical vapor deposition

“…Several studies have been done on silver and copper corrosion and revealed that silver sulfide is the main corrosion product obtained when the silver is exposed to indoor and outdoor environments [2][3][4][5][6][7][8][9]. This corrosion film induces an insulating layer at the contact surfaces causing electrical failures on the devices.…”

Tarnishing of silver in environments with sulphur contamination

“…Considerable experience and a number of analytical techniques have been explored over the years concerning silver's tarnish and found sulphuration of silver caused tarnishing to occur (Fukuda and Fukushima, 1991; Vassiliou and Dervos, 1999; Mehan and Mansingh, 2000; Hindin and Fernandez, 2003). Tarnish means a darkening of the surface of silver and rendering it aesthetically unacceptable.…”