Wickham, M; Zou, L; Hunt, C (2008) Test method for recyclable electronic substrates utilising additive technology. NPL Report. MAT 16

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Abstract

Now that WEEE legislation has been implemented across Europe, there is significant interest in adopting more sustainable electronics manufacturing processes and materials. The changes may lead to alternative failure modes, and hence maintaining performance is key issue for the introduction of new materials. This work studies the performance of specific favoured materials to qualify the failure mechanisms and the effective stress screening regimes.
Flexible thermoplastic printed circuit assemblies based on printed polymer thick film inks and direct write copper on PET, were assembled using electrically conductive adhesives and tested using damp heat, thermal cycling, and combinations of these. Three generic interconnect styles were investigated.
For the majority of conductive adhesive/component combinations, damp heat conditioning was found to develop the most damage, and is typical of industrial environments. Where degradation was observed, conductive adhesive joints developed high resistance failures. Separation occurred along the component/adhesive interface. It is speculated that this is a combination of a cohesive failure of the epoxy binder in the conductive adhesive, plus an adhesive failure in the vicinity of the oxide film formed on the surface of the component, which could be adhesive to oxide or oxide to metal failures.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	MAT 16
Subjects:	Advanced Materials Advanced Materials > Electronics Interconnection
Last Modified:	02 Feb 2018 13:15
URI:	http://eprintspublications.npl.co.uk/id/eprint/4131

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