Formation of SiO/sub 2/ on contact surface and its effect on contact reliability

Electrical contact failure due to thermal decomposition of low-molecular-weight silicone vapor evaporated from such silicone products as oils and rubbers was investigated in a simulated environment. A glassy film deposit was found on the contact surface after exposure to elevated temperature in an atmosphere containing an extremely small quantity of the silicone. The film was clearly identified as amorphous SiO/sub 2/ by ellipsometry, X-ray photoelectron spectrometry (XPS), and X-ray diffractometry (XRD). The growth of the film was directly related to the concentration of silicone vapor and temperature. The growth law was an exponential function of the exposure time. The film increases static contact resistance when it is thicker than 800 AA and the load is less than 5 g. The relationship between the concentration of the vapor, temperature, film thickness, and contact resistance is represented schematically.<
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