While it is important to have at least 10µm of solder on each side of a tabbing ribbon to form a proper solder joint during cell interconnection, more is not always better. What we have found is that thicker solder coatings may provide adequate and consistent solder joints, but at a reduced bond strength.
The test was performed on c-Si cells, with an industry leading flux, and 3 sets of tabbing ribbon with different solder coating thicknesses. The tabbing ribbon was made from the same ribbon stock to minimize any variation between test subjects. The samples were prepared on a Komax X-series tabber/stringer, and the tabbed cells were allowed to rest at ambient conditions for >48 hours after soldering to relieve stresses. Next, the tabbing bonds on each cell were peel tested at 90°F using a XYZTEC Condor 150-3. Average (not peak) bond force values across the cell were recorded.
We are happy to apply custom solder coating thickness to tabbing ribbon for you.
I hope this helps you make a good decision when you are specifying material.
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