Modelling of process and reliability of press-fit interconnections

This investigation is aimed at the stability of press-fit interconnections for MID. Moulded interconnect devices (MID) are 3-dimensional substrates produced by thermoplastic injection moulding for large-series applications. The assembly process of press-fit interconnections has been correctly modelled with a FE-Software. With this model the behaviour of the mechanical contact pressure, which decreases due to creep in the thermoplastic base material, could be described. Especially, the modelling is a tool to optimize pin and hole geometries. In order to obtain realistic results, the creep law parameters for the applied base material, a liquid-crystal polymer (LCP), was fitted to experimental. The required coefficients of friction were determined by adapting the simulations to the experiments. The time-dependent retention force between a pin and the substrate directly after assembly or after temperature loads could be predicted with finite element analyses, which was used as reliability criterion.