Decomposition of no-clean solder flux systems and their effects on the corrosion reliability of electronics
- 338 Downloads
No-clean flux systems are used today for the soldering of electronic printed circuit board assemblies assuming that all the aggressive substances of the flux will vanish during the soldering process i.e. evaporate, decompose or being enclosed safely in the residues. However this is not true in most cases, as the flux residue left on a printed circuit board assembly is a key factor compromising the corrosion reliability under humid conditions. This investigation focuses on the chemical degradation of three kinds of solder flux systems based on adipic, succinic, and glutaric acid as a function of temperature, thus simulating the soldering process. Differential Scanning Calorimetry, Fourier Transform Infrared Spectroscopy, and Ion Chromatography were employed for decomposition and residue analysis. Aggressiveness of the residue was investigated using a pH indicator gel test and by acid value determination. Effect on corrosion reliability was investigated by exposing the test printed circuit board assemblies to humidity after pre-contaminating with pure acids and desired solder flux systems and measuring the charge transferred between electrodes under applied potential bias. Results showed that the fluxes do not decompose fully within the temperature regime of the soldering process, leaving behind significant level of weak organic acid residues. The residue depending on the type and amount can be can be very aggressive towards the corrosion on the printed circuit board assemblies. The glutaric acid based flux showed highest leakage current when exposed to humidity compared to the adipic and succinic based fluxes.
KeywordsSuccinic Acid Soldering Process Adipic Acid Thermo Gravimetric Analysis Glutaric Acid
Current research has been conducted as part of the CELCORR/CreCon consortium (www.celcorr.com) and the authors acknowledge the funding from the consortium partners and for their commitment and help.
- 1.T. Munson, Foresite Inc., www.residues.com. Accessed 02 July 2014
- 2.M.L. Minges, Electronic Materials Handbook, vol. 11, 1st edn. (ASM International, Almere, 1989)Google Scholar
- 4.P. Biocca (2001) in Proceedings of Surface Mount Technology Association (SMTA International) 2001, Chicago, Illinois, 30 Sept to 4 Oct 2001Google Scholar
- 8.T. Munson, Foresite Inc., PDF-file at www.residues.com, 07 June 2012
- 10.T. Munson, Circuits Assem. 17(11), 44 (2006)Google Scholar
- 11.K. S. Hansen, M. S. Jellesen, P. Westermann, P. Møller, and R. Ambat et al. (2009) in Proceeding of Annual Reliability and Maintainability Symposium (RAMS 2009), Fort Worth, United States,pp. 502–508, 26–29 Jan 2009Google Scholar
- 12.K. Sweatman, J. Masuda, T. Nozu, M. Koshi and T. Nishimura (2010) in Proceeding of IPC APEX EXPO Technical Conference 2010, Las Vegas, United States, 2, pp. 921–925, 6–9 April 2010Google Scholar
- 22.C. Dominkovics, G. Harsanyi (2006) in Proceeding of 29th International Spring Seminar on Electronics Technology (ISSE), St. Marienthal, Germany, pp. 206–210, 10–14 May 2006Google Scholar
- 23.D.R. Lide, CRC Handbook of Chemistry and Physics (Chemical Rubber Publishing Company, Boca Raton, 1994)Google Scholar
- 24.D. Minzari, M. S. Jellesen, R. Ambat, P. Møller, P. Westermann (2009) Patent Number: WO2011048001-A1, 21 Oct 2009Google Scholar
- 25.D. Minzari (2010) PhD thesis, Mechanical Department, Technical University Denmark, Lyngby, DenmarkGoogle Scholar