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Effects of Surface Roughness and Aging on the Electrical Contact Resistance and Residual Stress in Gold-Nickel-Copper Connector Materials

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Master's thesis

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The purpose of this research is to investigate the effects of surface roughness and aging environment on the electrical contact resistance and residual stress in nickel and nickelgold coated copper. In order to accomplish these research objectives, oxygen free copper coupons were prepared to a variety of average surface roughnesses Ra ranging from 0.05 urn to 2.5 urn prior to coating application. Three coating systems were investigated AuNi plating, Ni plating, and Ni sputtering. The majority of this research focuses on the AuNi plated samples, with Ni plated and Ni sputtered data included for comparison. Nickel, gold, and copper are commonly used in electrical components, such as electrical contacts, in which component reliability is of great importance. As there are a wide variety of environments to which electrical components could be exposed to during service, the coated samples were aged for up to nine weeks in one of three aging environments mixed flowing gasatmospheric corrosion MFG, elevated temperature and relative humidity TRH, and thermal cycling TC. The mixed flowing gasatmospheric corrosion environment was created by using a Battelle Class 2 environment with the following conditions 30 C, 70 relative humidity, 200 ppb N02, 10 ppb H2S, and 10 ppb CU. The elevated temperature and relative humidity environment maintained samples at a constant temperature and relative humidity of 40 C and 85, respectively. Samples in the thermal cycling environment were cycled between temperatures of-40 C and 60 C with a 15 minute dwell time and an approximately 4.5 Cminute ramp rate. Characterization using optical profilometry, optical microscopy OM, scanning electron microscopy SEM, energy dispersive x-ray spectroscopy EDS, x-ray diffraction XRD, and electrical contact resistance ECR measurements allowed for the determination of changes in the coupons due to the coating system, surface preparation, and environmental exposure.

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  • Electrical and Electronic Equipment

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