Numerical estimation of local load during manufacturing process in high temperature PCB resin based on viscoelastic material modeling

In the field of electric and autonomous driving applications, there is currently an increasing demand for high-performance PCB materials, which can meet the requirements of high durability and long-term stability. For example, high temperature PCB base materials with an increased glass transition temperature offer new possibilities and facilitate new fields of usage. However, to the best of our knowledge, their thermomechanical properties on the local scale of glass fiber and resin matrix regions are not widely reported yet. Important investigations on the deformation behavior and the load limits still have to be performed. The lack of a solid experimental data basis hampers the development of numerical simulation methods as a valuable tool for reliability prognoses. In this work, we employ a novel material characterization procedure focused on the local mechanical properties of the PCB resin matrix to support the material modeling for numerical simulations. The goal of the current work is to assess the capabilities of state of the art FE-assisted methods to describe the local material properties in critical locations of a PCB stack. Numerical modeling is performed on mechanical tensile tests as well as on an idealized PCB module subjected to a standard manufacturing profile. We investigate two strategies for modeling a PCB stack, namely as a homogenized block, and as a discrete layer-by-layer stack of filled resin matrix and glass fiber reinforced resin layers. The local loads in a PCB assembly resulting from the simulation of a manufacturing thermal profile are compared to the loads observed in tensile tests. We discuss the current capabilities and limitations in the applied FE-methodology, and we derive necessary improvements of the material modeling and the geometrical discretization approaches for PCB modules.