Nanocopper As A Replacement For Solder -- A Question Of Reliability?
Authors: Luke Wentlent, Karl Schnabl, S. Khasawneh, K. Mootoo, J. Owens, J. Jiang, A. A. Zinn, J. Beddow, R. Stoltenberg, J. Chang, E. Hauptfleisch, D. Blass, and Peter Borgesen, Ph.D. Company: Binghamton University, Department of Systems Science & Industrial Engineering; Lockheed Martin Space Systems Company, Advanced Technology Center'; and Lockheed Martin Mission Systems & Training Date Published: 10/13/2013
Abstract: As a microelectronics interconnect or bond material, solder offers a compromise between materials properties and processability. In comparison a material like Cu offers a number of obvious advantages. A Cu nanoparticle paste is under development that offers the potential for application by standard SMT technology, and formation of Cu joints at peak processing temperatures of about 200oC. So far the resulting strength and reliability do however remain well below those of bulk Cu. While they may still suffice under certain conditions broad scale implementation in most current applications will require quantitative comparisons with the performances of current SnPb and lead free solders. In the absence of an in-depth understanding of the individual damage and failure mechanisms involved such comparisons may easily become misleading. We outline our current understanding for common lead free solder alloys and present preliminary results of testing of Cu. Current damage accumulation rules have been shown to break down for SnAgCu alloys and appear to do so for Cu as well, but not necessarily with as serious consequences.