Really. Just add more flux than you think it could possibly need. The biggest failure mode I've seen with solder of all kinds is not enough flux.
This Amtech no-clean is really gooey[0], but pretty useful for rework.
This Kester water-soluble is incredible, but needs to be washed[1].
If you need to hand-clean PCBs, a small photography developing tub and a sonicare (or similar) toothbrush is a game changer.
[0] https://www.amazon.com/gp/product/B09Y7N6QHF
[1] https://www.amazon.com/gp/product/B00DEDB5CM
Really. Just add more flux than you think it could possibly need. The biggest failure mode I've seen with solder of all kinds is not enough flux.
This Amtech no-clean is really gooey[0], but pretty useful for rework.
This Kester water-soluble is incredible, but needs to be washed[1].
If you need to hand-clean PCBs, a small photography developing tub and a sonicare (or similar) toothbrush is a game changer.
[0] https://www.amazon.com/gp/product/B09Y7N6QHF
[1] https://www.amazon.com/gp/product/B00DEDB5CM