SAC solder paste with carbon nanotubes. Part II: carbon nanotubes’ effect on solder joints’ mechanical properties and microstructure

Krystyna Bukat , Janusz Sitek , Marek Kościelski , Wojciech Niedźwiedź, IMiIB , Anna Młożniak , Małgorzata Jakubowska

Abstract

The purpose of this work is to investigate the influence of carbon nanotube additions to solder paste on the solder joints mechanical strength and their microstructure. In our investigation, the basic solder paste contains 85 wt.% of the commercial Sn96.5Ag3Cu0.5 powder (with the particle sizes in the range of 2038 μm) and 15 wt.% of the selfprepared middle activated rosin flux. To this paste we added the 0.01, 0.05 and 0.1 wt.% of the selfmodified CNT by functionalized them by mineral acid and than esterificated by methanol (FCNT Met ) or polyethylene glycol 400 (FCNT PG ). After the pastes had stabilized, the reflow soldering process of “zero ohm” chip resistors on PCBs with Ni/Au and SAC (HASL) finishes was carried out and then shear strength of the solder joints was measured. The correlations between the mechanical strength of solder joins without and with the carbon nanotubes and their microstructure were analysed. For shear strength measurement of solder joints, the printed circuit boards with Ni/Au and SAC (HASL) finishes was applied. The SAC solder paste with different carbon nanotubes and the basic SAC solder paste as reference were used for this experiment. The automatic SMT line was applied for the paste screen printing; “zero ohms” chip resistors: 0201, 0402, 0603 and 0805 were placing on PWBs and then reflowing according to appropriate time – temperature profile. The shear strength of the solder joints was measured. For the solder joints microstructure analysis, the standard metallographic procedures were applied. Changes in the microstructure, the thickness of the intermetallic compounds and their chemical compositions were observed by means of the SEM equipped with EDS. As the authors expected, the SAC solder paste with the carbon nanotubes addition improve the solder joints shear strength of the chip resistors mounted on PCBs with Ni/Au and SAC (HASL) finishes. The carbon nanotubes addition positive effects on IMCs thickness because of blocking their excessive growth. It is suggested that further studies are necessary for the confirmation of the practical application, especially of the reliability properties of the solder joints obtained using solder paste with chosen carbon nanotubes. Taking into account the shear strength data, the best results of the “nano” SAC solder pastes were obtained for the lowest addition of the carbon nanotubes modified by esterification process, especially by the methanol compared to the polyethylene glycol 400. The obtained results made it possible to draw conclusions regarding the correlation between the output of the mechanical results and the amount of the added carbon nanotubes, and also the microstructure and thickness of the IMCs of the “nano” solder joints. It can be useful from practical point of view. © 2013, Emerald Group Publishing Limited

Author Krystyna Bukat - [Instytut Tele-i Radiotechniczny, Warszawa]
Krystyna Bukat,,
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, Janusz Sitek - [Instytut Tele-i Radiotechniczny, Warszawa]
Janusz Sitek,,
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, Marek Kościelski - [Instytut Tele-i Radiotechniczny, Warszawa]
Marek Kościelski,,
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, Wojciech Niedźwiedź, IMiIB
Wojciech Niedźwiedź, IMiIB,,
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, Anna Młożniak - [Instytutu Technologii Materialow Elektronicznych w Warszawie]
Anna Młożniak,,
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, Małgorzata Jakubowska (FM / IMBE)
Małgorzata Jakubowska,,
- The Institute of Metrology and Biomedical Engineering
Journal seriesSoldering & Surface Mount Technology, ISSN 0954-0911
Issue year2013
Vol25
Pages195-208
ASJC Classification2208 Electrical and Electronic Engineering; 3104 Condensed Matter Physics; 2500 General Materials Science
DOIDOI:10.1108/SSMT-08-2012-0021
Languageen angielski
Score (nominal)20
Score sourcejournalList
ScoreMinisterial score = 20.0, 11-02-2020, ArticleFromJournal
Ministerial score (2013-2016) = 20.0, 11-02-2020, ArticleFromJournal
Publication indicators Scopus Citations = 7; WoS Citations = 4; GS Citations = 1.0; Scopus SNIP (Source Normalised Impact per Paper): 2013 = 0.513; WoS Impact Factor: 2013 = 0.688 (2) - 2013=0.61 (5)
Citation count*1 (2015-03-08)
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* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.
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