Quantification of Pin Fretting in the PCB Connectors Subjected to Random Vibration Excitation

Severe operating vibrations make the printed circuit boards (PCBs) connectors susceptible to an intermittent high contact resistance, which eventually leads to a failure resulting in the loss of signal integrity. Pin fretting within the mating connector is often the cause of this failure. In this paper, a new methodology is developed to study the pin fretting within the mating PCB connector. The methodology developed is based on the quantification of relative motion as a measure of pin fretting, considering the dynamics of printed circuit board assemblies (PCBAs) and mounting brackets. The behavior of the system is investigated by exciting the system (i) using the generated white noise time series and (ii) the random vibration signal. A pseudo random time series signal is derived from the power spectrum density (PSD) of the signal and the derived time series signal is used to excite the system. The relative response vector is computed from the response of the system. The results of the relative motion of the mating connector are presented in terms of the maximum amplitude of relative motion and the cumulative relative movement. The significance of the cumulative relative movement is that the complex phenomenon of pin fretting in the mating connectors can be represented by a simple time series model that can be used to correlate the material degradation. A numerical example based on finite element analysis is presented in the backplane connectors to demonstrate the proposed methodology. The example shows that the method proposed here is systematic and constructive in quantifying the pin fretting behavior.