Determination of cyclic mechanical properties of thin copper layers for PCB applications

The overall objective of this research work is the characterization of the mechanical behavior of Printed Circuit Boards (PCBs) under cyclic thermal loads. The conducting traces in PCBs are made from thin copper layers in an etching process. Hence, thin copper layers are characterized experimentally and subsequently cyclic material parameters are determined. The experimental characterization is conducted using cyclic tensile-compression tests at different temperatures and loading conditions. For these tests composite specimens made of five layers of copper and four layers of glass fiber reinforced epoxy resin are used. The obtained material response is modeled using the “Nonlinear isotropic/kinematic hardening model” built-in in the Finite Element Analysis-software Abaqus. For every loading case the optimal set of parameters is determined using an optimization procedure. Based on the known parameter sets of the individual loading cases the calibration of a “Nonlinear isotropic/kinematic hardening model” for all R-ratios and temperatures is attempted and the findings are discussed.