This paper presents a study on the contact resistance behaviour of elastomer sockets used to interconnect microprocessors and printed circuit boards in enterprise servers. The integrated circuit sockets, installed in production representative assemblies, were evaluated at 25 ◦C, 55 ◦C, and 75 ◦C for 2000 h. A sample subset was evaluated up to 16 500 h at 25 ◦C and up to 4500 h at 55 ◦C. The test results show that contact resistance decreases over time for all test conditions, as much as 50% from their initial values. Elastomer contact behaviour is strongly dependent on temperature and time. The resistance behaviour over temperature is modeled with multiple statistical distributions. The mean contact resistance is represented with a physics-of-failure model, and the elastomer contact reliability is estimated using a log-normal distribution.
Index Terms: Accelerated testing, contact resistance, elastomer socket, physics of failure (PoF).
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