Investigation of Relaxation Behavior for Terminals of CPU Socket Connectors

Terminals of a CPU socket connector dominate signal transmission between the CPU and the motherboard. Contact forces between the terminal of an electronic connector and the corresponding counterparts generally play an important role in signal transmissions. The contact forces of these terminals, however, could decay gradually due to the stress relaxation effect under the high temperature conditions. A finite element analysis is carried out to examine the relaxation phenomenon of the terminal in the present study. The strain-hardening form of the power-law creep model is adopted to account for the relaxation behavior of the terminal material. According to the field life acceleration test specifications established by the Electronic Industry Association (EIA), relationships between the calculated contact force and duration period are then constructed. Moreover, the contact force of the terminal subjected to thermal cycling test is also investigated. Calculations show that the decreased amount of the contact force is rather limited. Associated electrical resistances of the current terminal are further measured to validate the suitability of the contact force as an index of the signal transmission quality.