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Low-temperature soldering for the interconnection of silicon heterojunction solar cells

 
: De Rose, A.; Erath, D.; Geipel, T.; Kraft, A.; Eitner, U.

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Fulltext urn:nbn:de:0011-n-5039886 (760 KByte PDF)
MD5 Fingerprint: 6fbc197debe9b11bec3bad43bcd99013
Created on: 17.8.2018


Smets, A.:
33rd European Photovoltaic Solar Energy Conference and Exhibition, EU PVSEC 2017 : Proceedings of the international conference held in Amsterdam, The Netherlands, 25 September - 29 September 2017
München: WIP, 2017
ISBN: 978-3-936338-47-8
ISBN: 3-936338-47-7
pp.710-714
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <33, 2017, Amsterdam>
English
Conference Paper, Electronic Publication
Fraunhofer ISE ()
photovoltaisches Modul; Systeme und Zuverlässigkeit; Photovoltaik; Photovoltaische Module und Kraftwerke; Modultechnologie; heterojunction; interconnection; Low-Temperature; Soldering

Abstract
Interconnecting silicon heterojunction (SHJ) solar cells by low-temperature ribbon soldering allows the use of standard stringing equipment and might therefore be the cheapest and most straightforward implementation in existing fabrication lines. However, solder joints on low-temperature metallization pastes of SHJ cells are known for a weak adhesion to the cell surface. This work is dedicated to a better understanding of the interaction between solder and low-temperature metallization on SHJ solar cells. We evaluate soldering during a lamination process with standard copper ribbons featuring six different low-temperature solder alloys. The mechanical adhesion of the solder joints and microstructural changes in the metallization pastes during the soldering process are analyzed. Our study includes three metallization pastes, two of them show poor adhesion on the wafer surface after soldering (up to 0.03 N/mm) and one paste performs slightly better (up to 0.28 N/mm). We find this difference to be caused by an interaction of the pastes and the liquid solder, neither depending on the composition of the solder alloy nor on the soldering time. A fine grain structure of the Ag-particles of such pastes correlates with a higher penetration of solder components (Sn and Bi) resulting in dissolution of the metallization and detachment from the cell surface.

: http://publica.fraunhofer.de/documents/N-503988.html