Dusek, M; Nottay, J; Hunt, C; Lu, H*; Bailey, C* (2001) An experimental validation of modelling for Pb-free solder joint reliability. NPL Report. MATC(A)11

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Abstract

Assessing/predicting the reliability of solder joints on electronic components has traditionally involved accelerated thermal cycling. However, such testing can be time-consuming and expensive since one cycle can be as long as an hour and it may take several thousands of cycles before failure of the joint. Any test procedures, say using computer modelling, to shorten this evaluation period will therefore offer significant benefits to the industry.
This report presents the findings of an initial collaboration study of the use of a particular software-model combination to predict trends in solder joint failures and compare them with those observed experimentally. In the latter, the joints, which were made using two lead-free solders, were stressed using four different thermal cycling regimes, including one typical of that used in automotive products and the other appropriate for military equipment. The results were benchmarked against those obtained using conventional SnPb solder. The findings are encouraging in that the model successfully predicted the failure trends observed in the joints and hence forms a good base for further stages of the work. Differences in the absolute numbers of cycles to failure observed experimentally and predicted theoretically are attributed to the sensitivity of the constitutive equations used and the fact that the model (knowingly) did not take crack propagation into account. The results indicate that the joints associated with a simple 2512-type resistors provided a good test vehicle for this type of study. Moreover, the findings demonstrate that a 3D modelling approach is essential to characterise the changing stress and strain patterns experienced by the joint through each thermal cycle.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	MATC(A)11
Keywords:	solder, reliability, lead-free, modelling
Subjects:	Advanced Materials Advanced Materials > Electronics Interconnection
Last Modified:	02 Feb 2018 13:17
URI:	http://eprintspublications.npl.co.uk/id/eprint/2307

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