Determination of the orthotropic material properties of individual layers of printed circuit boards

To improve the reliability of printed circuit boards (PCBs), occurring failure modes have to be studied and analysed. In order to reduce the expenses of experimental testing, finite element analysis (FEA) is used to describe the failure behaviour. Therefore, the availability of the proper material data is crucial. As the materials used in printed circuit boards, glass fibre reinforced epoxy resin and structured copper, show anisotropic material behaviour, it is necessary to determine the direction-dependent material properties. However, as only very thin layers were available of these materials, no experimental mechanical out of plane characterisation could be performed. Thus, a combination of experiments, mean-field calculations and FEA simulations was used to generate the material data for both, the insulating and the conducting layers of the PCB. The generated material models were tested in board level simulations and compared to the results of simulations based on isotropic material behaviour. Significant differences were observed, approving the importance of proper material data, especially when the local stress and deformation field are important.