Simple question..., I am going to replace motor, just wonder if I should remove old shiny solder (from ESC pad) and put a new one ..or just try to use 'existing joint' what I am tempted to do ?

The solder already on the board will likely be the unleaded type so your best option is to remove as much of it as possible rather than mixing new leaded solder with it. Flux and solder wick will do that job for you. Then just re-tin with fresh leaded solder and solder your motor wires as per usual. Don't forget to use plenty of flux.

If it was good solder that is on the pad, I would just try to re-use it as is. If it was a pre-built quad I'm not sure if they use leaded solder, or do they have to use non-leaded.

You can always just try, and if it doesn't work out then try to remove the old solder and put new good solder on.

(27-Jul-2021, 04:37 PM)MrSolo Wrote: If it was good solder that is on the pad, I would just try to re-use it as is.  If it was a pre-built quad I'm not sure if they use leaded solder, or do they have to use non-leaded.

You can always just try, and if it doesn't work out then try to remove the old solder and put new good solder on.

Most Chinese companies seem to use that junk lead-free stuff. If you try to mix leaded solder with the non-leaded stuff you can just end up making life difficult for yourself. Better to play it safe by cleaning off all the original solder first then re-applying known good leaded solder. There is no point risking potential overheating and lifting of pads for the sake of cutting corners, IMO.

International RoHS (Restriction of Use of Hazardous Substances) regulations limit specific substances – lead, cadmium, polybrominated biphenyl (PBB), mercury, hexavalent chromium, and polybrominated diphenyl ether (PBDE) flame retardants – in electrical and electronic equipment. The Maximum Concentration Value (MCV) for heavy metals under RoHS standards are: Lead (0.1 %), Mercury (0.1 %), and Cadmium (0.01 %).

Chinese companies aren't using lead-free solder just for kicks.

Yeah, IF your sitting in a sweatshop 15hrs a day, poor air circulation ect.. and I THINK lead free is cheaper..
The little bit of soldering that gets done by a hobbiest, in a WELL ventilated are.. and maybe a small fan /vacuum to evacuate the fumes would not hurt..
The quality of ur solder joints will be cleaner, faster, easier with lead solder…

(19-Apr-2022, 06:53 PM)Rob Axel Wrote: Yeah, IF your sitting in a sweatshop 15hrs a day, poor air circulation ect..

The lead doesn't evaporate, the flux does. Lead-free can actually be worse for the respiratory system because you need more flux.

Do you think that most of the Chinese companies who manufacture stuff for our hobby actually care about regulations? How many fake CE marks do we see on Chinese produced goods? Not to mention all the plastic based toys that contain toxic and/or carcinogenic chemicals. The Chinese companies we deal with in this hobby are likely using lead-free solder simply because it's cheaper and probably easier to source than most leaded equivalent solders, not to adhere to regulations.

(19-Apr-2022, 07:20 PM)SnowLeopardFPV Wrote: How many fake CE marks do we see on Chinese produced goods?

The mark in question is China Export. Its not their fault if you get confused...................  


The DT Teachers at the school I run a club at refuse to use unleaded, much to the Lab Tech's anguish!