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Reliability of joints formed with mixed alloy solders.

Brewin, A; Hunt, C; Dusek, M; Nottay, J (2002) Reliability of joints formed with mixed alloy solders. NPL Report. MATC(A)85

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The introduction of lead-free solders into the re-work arena will potentially involve the mixing of a wide variety of alloys in the resulting joints. This reports investigates the effect on joint reliability of mixing alloys likely to be in production and rework during the transition to lead-free soldering technologies. SnPb, SnPbAg, SnCu, SnAgCu and SnAgBiCu alloys were used in a range of mixtures to make surface mount joints. The reliability of the joints was assessed using thermal cycling with continuity monitoring and shear testing.
The continuity data is fitted to a Weibull distribution and 'first failure' reliability is defined as the number of thermal cycles at which 1 % of the population of solder joints tested has failed (equivalent of first joint failure on a board of 100 solder joints). The results indicate that when solder alloys are mixed the resultant joint exhibit a general improvement in first failure reliability as compared with those soldered using the single alloys. This finding suggests that concerns about mixing og alloys in rework situations, may be unfounded.

Item Type: Report/Guide (NPL Report)
NPL Report No.: MATC(A)85
Keywords: lead-free, solder joint, reliability, shear testing, Weibull, ultimate shear strength, rework
Subjects: Advanced Materials
Advanced Materials > Electronics Interconnection
Last Modified: 02 Feb 2018 13:17
URI: http://eprintspublications.npl.co.uk/id/eprint/2333

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