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Crack detection methods for lead-free solder joints.

Dusek, M; Hunt, C (2004) Crack detection methods for lead-free solder joints. NPL Report. MATC(A)164

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This report describes an investigation into the suitability of a number of techniques used to study cracking in lead-free solder joints, and hence their use in assessing joint lifetimes. Cracks were induced into the solder joints of chip resistors on FR4 substrates, and studied using metallographic micro-sectioning, dye penetration, mechanical test and thermal conductivity techniques. The work has shown that those techniques traditionally used to study lead-based solder joints can readily be used for assessing lead-free solder joints The traditional microsectioning method is suitable for locating and imaging the solder joint crack, especially when the section is examined in a SEM. However, it is not very suitable for quantitative analysis of cracks or their detection in small surface mount resistors. Dye penetration techniques allow a better characterisation of cracks in the horizontal plane and can provide a quantitative measure of the cracked surface area. Shear testing is a proven destructive method for evaluating not only the degree of crack propagation and damage to the solder joint, but also the general strength of the joint. The other methods studied (3 and 4-point bend tests, pull test and heat transfer) have severe limitations and are currently unsuitable for studying cracks in the solder joints of electronic assemblies, requiring further development.

Item Type: Report/Guide (NPL Report)
NPL Report No.: MATC(A)164
Subjects: Advanced Materials
Advanced Materials > Electronics Interconnection
Last Modified: 02 Feb 2018 13:16
URI: http://eprintspublications.npl.co.uk/id/eprint/2973

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