Method development for the cyclic characterization of thin copper layers for PCB applications
Abstract
Purpose
The overall aim of this research work was the improvement of the failure behavior of printed circuit boards (PCBs). In order to describe the mechanical behavior of PCBs under cyclic thermal loads, thin copper layers were characterized. The mechanical properties of these copper layers were determined in cyclic four-point bend tests and in cyclic tensile-compression tests, as their behavior under changing tensile and compression loads needed to be evaluated.
Design/methodology/approach
Specimens for the four-point bend tests were manufactured by bonding 18-μm-thick copper layers on both sides of 10-mm-thick silicone plates. The silicone was characterized in tensile, shear and blow-up tests to provide input data for a hyperelastic material model. Specimens for the cyclic tensile-compression tests were produced in a compression molding process. Four layers of glass fiber-reinforced epoxy resin (thickness 90 μm) and five layers of copper (thickness 60 μm) were applied.
Findings
The results showed that, due to the hyperelastic material behavior of silicone, the four-point bend tests were applicable only for small strains, while the cyclic tensile-compression tests could successfully be applied to characterize thin copper foils in tensile and compression up to 1 percent strain.
Originality/value
Thin copper layers (foils) could be characterized successfully under cyclic tensile and compression loads.
Keywords
Acknowledgements
The authors would like to thank Michael Berer for technical assistance at the Bose 3230 and Bernd Schrittesser for help with the blow-up tests. Daniel Tscharnuter and Harald Schmid designed the device used for V-notched rail shear testing and tensile-compression testing in this work. Martin Birker prepared the specimens and helped with the testing. Stefan Hinterdorfer and Juergen Grosser provided contributions to the MTS testing. The research work of this paper was performed at the Polymer Competence Center Leoben GmbH (PCCL, Austria) within the framework of the COMET-program of the Austrian Ministry of Traffic, Innovation and Technology with contributions by the University of Leoben and by the AT&S Austria Technologie & Systemtechnik Aktiengesellschaft. The PCCL is funded by the Austrian Government and the State Governments of Styria and Upper Austria.
Citation
Fellner, K., Fuchs, P.F., Pinter, G., Antretter, T. and Krivec, T. (2014), "Method development for the cyclic characterization of thin copper layers for PCB applications", Circuit World, Vol. 40 No. 2, pp. 53-60. https://doi.org/10.1108/CW-09-2013-0032
Publisher
:Emerald Group Publishing Limited
Copyright © 2014, Emerald Group Publishing Limited