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Thermal cycling reliability of Sn-Zn lead-free solders in sensor application

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review


Original languageEnglish
Title of host publicationECTC 2015, Electronic Components and Technology Conference, May 26-29, 2015, San Diego, USA
PublisherInstitute of Electrical and Electronics Engineers IEEE
Pages1240 - 1246
Number of pages7
ISBN (Print)9781479986095
Publication statusPublished - 2015
Publication typeA4 Article in a conference publication
EventElectronic Components and Technology Conference -
Duration: 1 Jan 1900 → …


ConferenceElectronic Components and Technology Conference
Period1/01/00 → …


There is a demand for low melting temperature solder in some applications (e.g., sensor attachment) where the components being soldered are temperature-sensitive. However, the same solder needs to meet the life cycle reliability requirements for the entire product. Among low temperature lead-free solders, eutectic Sn-9%Zn (wt.%) lead-free solder offers good mechanical reliability and low melting temperature. However, the presence of Zn makes it susceptible to oxidation especially at elevated temperatures. In this paper, the reliability of sensor attachments using Sn-9%Zn solder and capillary underfills was studied under thermal shock. Three different underfill materials were used with two of them containing fillers. The thermal shock test results showed that the underfills substantially improved the lifetime of the solder joints, and the underfills wth fillers provided the best mechanical support to the solder joints. The reliability of the Sn-9%Zn solder joints with underfills was found to be comparable to that of the Sn-Pb-2%Ag solder joints. Failure analysis revealed that a uniform distribution of the underfill was critical to achieve a reliable sensor attachment.