A new simulation approach to characterizing the mechanical and electrical qualities of a connector contact

Due to ongoing miniaturization in electronics, connector contact designs have to follow the same trends. The prediction of the mechanical and electrical performance of low force connector contacts becomes increasingly important. This paper shows a new approach for modeling elastic plastic contact between two multi-layered non-conforming rough bodies subjected to pressure and shear traction. Three main considerations will be presented: realistic surface simulations, numerical simulation of contact interfaces, and constriction resistance calculations. (i) Since measured three dimensional (3D) digitized surface data is not always available, having the ability to numerically simulate “realistic” rough surface topographies is of great importance. It will be shown how realistic engineered surfaces can be modeled using five scale independent parameters: RMS roughness, x/y correlation length, kurtosis and skew. (ii) A numerical algorithm has been developed which calculates the stresses and deformations generated in a contact system with up to three different layers per contact partner. The mechanical properties of each individual contact layer are incorporated into the calculation. This numerical algorithm is based on Papkovich-Neuber Potentials, both multi grid and conjugate gradient methods are used, and the plastic deformation of the individual contact points (a-spots) can be interpolated using different material hardening behaviors. (iii) Once the contact interface a-spot distribution is simulated, the constriction resistance of the true contact area can then be calculated. The voltage drop within the contacting bodies is interpolated by iteratively solving the Laplace equation. The electrical properties of all the individual contact layers as well as the interaction between the individual a-spots are taken into account. A validation of these simulation algorithms will be shown using a hard Au/Ni/CuSn6 contact system. The results show excellent agreement between measured and simulated contact resistance results over a normal force range from 1 cN up to 250 cN. The algorithms have been implemented with an “easy to use” Windows software interface called “First Contact”. The software also incorporates a material database that when used together with a surface modeler, allows for the fast calculation and 3D visualization of all mechanical and electrical contact characteristics.