Assessing the Reliability of Elastomer Sockets in Temperature Environments

This paper presents a study on the contact resistance behavior 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 $^{circ}hbox{C}$ , 55 $^{circ}hbox{C}$, and 75 $^{circ}hbox{C}$ for 2000 h. A sample subset was evaluated up to 16 500 h at 25 $^{circ}hbox{C}$ and up to 4500 h at 55 $^{circ}hbox{C}$. The test results show that contact resistance decreases over time for all test conditions, as much as 50% from their initial values. Elastomer contact behavior is strongly dependent on temperature and time. The resistance behavior 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.