Lea, D; Dusek, M; Jonck, F; Hunt, C (2001) Solderability of electrical components and copper using lead-free alloys. NPL Report. CMMT(A)284

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Abstract

As the move towards lead-free soldering gathers pace, there is keen interest in issues of solderability, arguably the key parameter for successful implementation of these new soldering technologies. This report presents the results of a large experiment to generate relevant solderability data using the wetting balance technique. The matrix experiment involved 20 component types (including both surface mount and through hole), copper coupons, 3 lead-free solders, 5 fluxes, a range of superheat temperatures, and two soldering atmospheres. The results were bench-marked against those for conventional SnPb solder.
The results demonstrate that nitrogen inerting is beneficial to solderability when unactivated rosin fluxes are used. Coupled with the lower superheat associated with lead-free solder alloys, this should result in a much wider industrial use of nitrogen inerting. The soldering temperature appears to exert a greater influence on solderability than non-clean flux chemistry. Of the lead-free alloys explored, SnAgCu appear to be the most attractive - it gives the best wetting characteristics, and it has the lowest soldering temperature. SnCu performed poorly, often with unacceptable solderability behaviour, even at the highest superheat. However, a key outcome of this work is that alloy selection for each component type is important, and that optimal selection is possible. The influence on solderability of flux type, temperature and solder type for each of the 20 component types has been calculated in this work. Relevant data, including typical wetting forces and wetting times, are listed in Appendices.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	CMMT(A)284
Subjects:	Advanced Materials Advanced Materials > Electronics Interconnection
Last Modified:	02 Feb 2018 13:17
URI:	http://eprintspublications.npl.co.uk/id/eprint/2126

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