Effect of the Soldering Atmosphere on the Wettability Between Sn4.0Ag0.5Cu (in wt.%) Lead-Free Solder Paste and Various Substrates

Effect of the Soldering Atmosphere on the Wettability Between Sn4.0Ag0.5Cu (in wt.%) Lead-Free... The “degree of wetting,” which is related to the contact angle (θ) between the molten solder and the substrate, is a useful parameter on the solderability process control. The contact angle, however, is strongly dependent on the type of substrate surface finish and used atmosphere (inert or non-inert). Furthermore, the surface tension, being an important parameter on the solderability process and performance, can also be achieved if the contact angle is known. In this study, the SAC405 [Sn4.0Ag0.5Cu (in wt.%)] solder paste contact angle was measured, by the “sessile drop” method, as a function of the temperature, surface pad finish and used atmosphere. The results are discussed, and the contact angles obtained for the different conditions are compared and discussed. Then, the surface tension (experimental) was obtained from the measured contact angle and compared with the obtained by using computation models (theoretical). The experiments performed in high vacuum conditions, i.e., low oxygen content, over a temperature range, allowed the evaluation and understanding of the surface oxides layers role on the solder wettability. The present study shows that in the soldering process, even in an inert atmosphere, usually used in industry, occurs the formation of superficial oxides, over the liquid solder and/or at the pad surfaces, that strongly affects the solder paste wettability, specially with Sn and OSP (organic solderability preservative) finishing. Differences in contact angle of ≥ 10° were determined between the two types of used atmospheres. The experimental surface tension and theoretical surface tension obtained, for the NiAu substrate type, present good correlation. The lower contact angle values were obtained for the NiAu and OSP finish types, independently of the atmosphere type. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Materials Engineering and Performance Springer Journals

Effect of the Soldering Atmosphere on the Wettability Between Sn4.0Ag0.5Cu (in wt.%) Lead-Free Solder Paste and Various Substrates

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Publisher
Springer Journals
Copyright
Copyright © 2018 by ASM International
Subject
Materials Science; Characterization and Evaluation of Materials; Tribology, Corrosion and Coatings; Quality Control, Reliability, Safety and Risk; Engineering Design
ISSN
1059-9495
eISSN
1544-1024
D.O.I.
10.1007/s11665-018-3419-2
Publisher site
See Article on Publisher Site

Abstract

The “degree of wetting,” which is related to the contact angle (θ) between the molten solder and the substrate, is a useful parameter on the solderability process control. The contact angle, however, is strongly dependent on the type of substrate surface finish and used atmosphere (inert or non-inert). Furthermore, the surface tension, being an important parameter on the solderability process and performance, can also be achieved if the contact angle is known. In this study, the SAC405 [Sn4.0Ag0.5Cu (in wt.%)] solder paste contact angle was measured, by the “sessile drop” method, as a function of the temperature, surface pad finish and used atmosphere. The results are discussed, and the contact angles obtained for the different conditions are compared and discussed. Then, the surface tension (experimental) was obtained from the measured contact angle and compared with the obtained by using computation models (theoretical). The experiments performed in high vacuum conditions, i.e., low oxygen content, over a temperature range, allowed the evaluation and understanding of the surface oxides layers role on the solder wettability. The present study shows that in the soldering process, even in an inert atmosphere, usually used in industry, occurs the formation of superficial oxides, over the liquid solder and/or at the pad surfaces, that strongly affects the solder paste wettability, specially with Sn and OSP (organic solderability preservative) finishing. Differences in contact angle of ≥ 10° were determined between the two types of used atmospheres. The experimental surface tension and theoretical surface tension obtained, for the NiAu substrate type, present good correlation. The lower contact angle values were obtained for the NiAu and OSP finish types, independently of the atmosphere type.

Journal

Journal of Materials Engineering and PerformanceSpringer Journals

Published: May 29, 2018

References

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