An Open-Source Tool for FEM Modeling of Bent Flexible Circuits

Predicting the properties of flexible printed circuits (FPCs) before production is a significant challenge in their development. Traditional design flows model FPCs in a flat state, yet simulations of the actual bent shape of the circuits are required in forecasting their final, real-world behavior. Currently, only proprietary tools are available for simulating these 3D geometries, with no open-source alternatives. This paper introduces a novel open-source software tool that bridges this gap by transforming two-dimensional layout data from KiCad files into three-dimensional bent meshes ready for simulation. Initially, retrieved geometries are rendered according to a pre-defined stackup. To enable a seamless simulation workflow, the geometries must then undergo preprocessing, meshing and labeling. This paper significantly extends an earlier published algorithm by (1) supporting more bend shapes and (2) eliminating dependencies on external programs for geometry generation, omitting the necessity to do the meshing manually, and generating physical groups. These steps are now integrated in our tool, facilitating automatic mesh generation from layout files in a single step. Consequently, the software generates ready-to-use FEM meshes for external simulators, thus supporting a comprehensive open-source design and verification workflow. This work not only enhances the accessibility of FPC design and simulation but also underscores the broader applicability of open-source solutions for printed circuit board design.