Search documents

Browse topics

Document details

Bow Analysis After Soldering Process for Silicon Solar Cell with Special Bus Bar Pattern Design
P.-H. Tsai, Y.N. Chang, C.W. Chen, W.-P. Chen, C.-H. Wu
Cost Reduction, Fundamentals, Module Manufacturing, Modelling / Modeling, Multicrystalline, Design
Wafer-Based Silicon Solar Cells and Materials Technology
Subtopic: Manufacturing Issues and Processing
Event: 27th European Photovoltaic Solar Energy Conference and Exhibition
Session: 2DO.2.6
845 - 847
ISBN: 3-936338-28-0
Paper DOI: 10.4229/27thEUPVSEC2012-2DO.2.6
0,00 EUR
Document(s): paper


In order to reduce the multi-crystalline cell manufacturing costs, thinner wafer and a special bus bar design with less Ag usage are adopted. Therefore, the bowing problem becomes more important in the soldering process. In soldering process, the temperature raises to about 200 degrees Celsius. While copper ribbon contracts after soldering, different coefficients of thermal expansion between copper ribbon and silicon lead to mechanical stresses act on the wafer, which makes wafer bowing. Wafer under large bowing may either break in soldering process or crack in module process hence reduces the reliability of module. Thus for a better soldering performance, reducing the bowing is the main target. In this model bus bar in real side of cell is designed as 6 dashed lines pattern with only half Ag usage. In front side, bus bar remains continuous line pattern. Compare with general cell with continuous line bus bar in the same soldering condition, bowing of dashed pattern increased by 1~2 mm. The goal of this work was to investigate a theoretical model to estimate wafer bowing increment induced in soldering process. Moreover, the bowing can be improved by either modifying parameters in soldering or modifying dashed line patterns.