Strengthening a Weak Solder Joint

[EPHorizon]

Hi there. I finished assembling a new Crazyflie a while ago, but noticed after testing it that one of the motors was non-functional. Luckily the spare worked fine, and now the copter is up and flying like a dream! However, having to desolder and then resolder the joint (combined with my relatively amateur soldering skills) weakened the connection, and now the wire is only loosely held on. I can't for the life of me get it any stronger via soldering it, and fear if I try much more I may end up accidentally damaging something, though it still works well enough. The only thing I'm worried about is if it dislocates itself in a crash.

So my question is this: What would be the best way to strengthen the connection without soldering it again? I haven't dealt much with projects of this tiny of scale, so forgive my lack of electrical knowledge, but would a moldable insulator, like Sugru, be safe to use, or would I want something like conductive glue?

Thanks in advance, and thank you, Bitcraze, for this awesome device!

[tobias]

Can you maybe post a picture of the soldering? Often if the solder isn't good it is due to the lack of flux and instead of melting nicely it creates solder blobs. Applying sine new solder (with flux) would probably make the joint good again.

[EPHorizon]

The issue is exactly as you described it, but the main thing is that I honestly cannot bring myself to try and resolder it again. Having to remove the non-functioning motor forced me to resolder the new one on the reverse side of the board, as the hole was filled and I don't presently have the necessary rework tools to clear it. I used a good bit of flux while doing so, but either my solder or soldering iron must be low quality, because I still wound up with a tiny blob of it with the wiring barely attached.

If I had a few better tools to do so, or had a more experienced person on hand, I would try for a rework, but I don't presently see that happening. So for now, something to the effect of a little dab of sealant of some sort seems most appealing, if you have any thoughts.

[demcanulty]

You could strain relief the cable somehow so that if the wires flex in a crash, they won't be stressing the electrical connection. I would use a bit of kapton tape for that and just tape the loose coil wire to the board (a little bit away from the actual electrical connection). Some other tape or adhesive might also do the job well enough.