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Modelling the impact of conformal coating penetration on QFN reliability

Modelling the impact of conformal coating penetration on QFN reliability

Yin, Chunyan ORCID: 0000-0003-0298-0420, Stoyanov, Stoyan ORCID: 0000-0001-6091-1226, Bailey, Christopher ORCID: 0000-0002-9438-3879 and Stewart, Paul (2017) Modelling the impact of conformal coating penetration on QFN reliability. In: 2017 18th International Conference on Electronic Packaging Technology (ICEPT). IEEE, pp. 1021-1026. ISBN 978-1-5386-2973-4 (doi:https://doi.org/10.1109/ICEPT.2017.8046616)

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Abstract

The impact of conformal coating penetration on the solder joints' thermal fatigue reliability in QFNs was studied using computational modeling techniques. 3D finite element models were developed with consideration of realistic solder joint shape and the actual coating profile. Thermal mechanical simulations were carried out for three cycles under accelerated thermal test conditions of -25 to 100°C, 10 minutes ramp and 10 minutes dwell. The inelastic strain energy density accumulated over one temperature cycle was used as an indicator for solder damage in the QFNs under the applied thermal cycling load. The impact of coating penetration level on the solder damage in QFNs was investigated for two types of coatings with different properties. The results show that coating penetrated underneath the package has significant impact on the solder joint damage in QFNs and the level of this impact depends on the coating properties and penetration level. When coating penetration level decreases, damage in the solder joint does not always decrease. In order to prevent coating penetration underneath the package, an edgebond adhesive was applied on the edge of the QFN assemblies prior to the application of the conformal coating. The modelling results show that using edgebond adhesive can reduce the solder joint damage in the investigated QFNs and thus improve their thermal fatigue reliability. When edgebond adhesive is used, the impact of conformal coating on the reliability of solder joints in QFNs is significantly reduced.

Item Type: Conference Proceedings
Title of Proceedings: 2017 18th International Conference on Electronic Packaging Technology (ICEPT)
Additional Information: Conference held at Harbin, China, from 16-19 August 2017.
Uncontrolled Keywords: Coatings, Analytical models, Integrated circuit modeling, Solid modeling, Materials reliability
Subjects: Q Science > QA Mathematics
Faculty / Department / Research Group: Faculty of Architecture, Computing & Humanities
Faculty of Architecture, Computing & Humanities > Centre for Numerical Modelling & Process Analysis (CNMPA)
Faculty of Architecture, Computing & Humanities > Centre for Numerical Modelling & Process Analysis (CNMPA) > Computational Mechanics & Reliability Group (CMRG)
Faculty of Architecture, Computing & Humanities > Department of Mathematical Sciences
Last Modified: 20 Mar 2019 10:36
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: GREAT a
Selected for GREAT 2019: None
URI: http://gala.gre.ac.uk/id/eprint/20226

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