| Electronics > Beginners |
| Hot air soldering - balls |
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| Bud:
--- Quote from: KL27x on August 30, 2019, 10:42:28 pm ---This is probably down to the paste. The solder balls occur because the flux spatters as it heats up, and it flings little bits of paste around. When that paste reflows and dries out with nothing to attach to, it forms little solder balls. Blueskull recommends GC10 paste. I'd give that a try. He does a lot of this sort of thing, and the boards he makes look like they could go into a cell phone. --- End quote --- I second that, seems the paste issue to me. Try a different paste. |
| JonPyro:
Ok some more experiments below, board cleaned before. 20190831_151716.jpg was lots of heat 20190831_151756.jpg is of the stencil paste 20190831_151825.jpg is at 138 degrees for about a minute (datasheet says the paste melts at 138.) 20190831_152633.jpg was high heat then cleaned with IPA and stiff brush. None of them really successfully. Lots of balls and this is without the chipset to have to clean around. While the last one cleans up ok I don't think i could achieve it that clean once a small chipset was sitting there. Are my expectations too high for this? EDIT: with a brutal brushing the boards do clean up... |
| rs20:
Could you please provide a link to this solder paste's datasheet? Lead free solder generally has a higher melting point than leaded solder paste, not something as low as 138. Makes me wonder what paste you've actually got there. |
| JonPyro:
Sure, attached. |
| Illusionist:
It'll have a high level of bismuth in it, similar to the stuff they sell for reworking boards. |
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