DOMINIK HERKOMMER MEng
PhD Research Postgraduate (2007-2009)

e: dominik.herkommer@ul.ie

t: +353-61-202471

Dominik Herkommer graduated with a Masters of Mechanical Engineering fom the University of Applied Sciences Mannheim, Germany in 2006. As part of his studies, he completed an M.E. Thesis at the CALCE Center, University of Maryland: “Investigation of Creep Properties for SAC Solder and Implementation into FEA Simulations”. He has been awarded a postgraduate scholarship to study at Stokes, funded under the SFI Centre for Telecommunications Value-Chain Research (CTVR).

PhD Project Title: Reliability of Pb-free Solder Interconnections

Background: The context for this research is the European Union’s ban on hazardous substances in electronic equipment which will be imposed in mid-2006. The ban will stipulate the removal of lead from solder interconnections, a requirement which has significant implications for the design and manufacture of electronic equipment. A number of candidate lead-free solder alloys have been assessed, and there is consensus that a tin-silver-copper alloy (Sn-3.8Ag-0.7Cu) will be adopted by industry, primarily due to cost competitiveness. Some life trials have been conducted, comparing SnAgCu interconnections to conventional 63Sn37Pb solder under accelerated test conditions. No comprehensive reliability investigation has been reported to date, however, and there is a clear need for a reliability model in order to estimate the life of lead-free solder interconnections in electronic hardware. Such a model would improve the design process, refine test requirements, and underpin the estimation of warranty costs with greater accuracy. The theme of this project is the development of a reliability model for SnAgCu solder interconnections.

This objective of the research is to underpin the revision of an existing reliability model developed by Bell Labs for tin-lead interconnections. The objectives of the project are to develop physically-correct models for the failure mechanisms which afflict SnAgCu solders in telecomms applications, and to extract appropriate stress-life relationships. Extensive reliability knowledge is available for tin-lead solder, and the research project is envisaged to obtain equivalent information for SnAgCu solders. The anticipated outcome of the research will be a reliability model for SnAgCu solder interconnections – with a fundamental understanding of its applicability – that will form the basis of reliability predictions for lead-free telecomms products.

This project is conducted in collaboration with Bell Labs New Jersey and is a part of the Centre for Telecommunications Value-Chain Research (CTVR).

Publications to date

Herkommer, D., M. Reid, and J. Punch, In-Situ Optical Creep Observation and Constitutive Modelling of Joint-Scale SAC Solder Shear Samples, in EPTC. 2008: Singapore.
Herkommer, D., M. Reid, and J. Punch, In-Situ Creep Observation of Joint-Scale SAC Solder Samples under Shear Load, in SMTAI. 2008: Orlando, Fl.
Herkommer, D., M. Reid, and J. Punch, A Comprehensive Shear Testing Facility for Joint-Scale Solder Samples, in EuroSimE. 2008: Freiburg.
Cuddalorepatta, G., D. Herkommer, and A. Dasgupta, Stress Relaxation Characterization of Hypoeutectic Sn3.0Ag0.5Cu Pb-free Solder; Experiment and Modeling, in EuroSimE. 2007: London.
Varghese, J., Radig, G., Herkommer, D. and Dasgupta, A., 2005, "Hybrid Experimental and Computational Approach for Rate Dependent Mechanical Properties using Indentation Techniques", Proceedings of the 6th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments, EuroSimE, pp. 510-514.