Isolate wires soldered on PCB

Question

I'm soldering some cables on a PCB. They are are stranded, so I've first apply a bit of soldering on them and then solder them on my pcb.

The problem is, there's on some a bit of exposed copper on the basis (1 or 2 mm) and they are soldered really close.

For now I don't have any short but it's still dangerous as they can move and ends in a position where the 1-2mm exposed of two can touch.

My idea was to use hot glue on the base of the wire to isolate them and avoid the possibility of shorts.

Do you think it's a good idea or I should do something else ? Perhap's a soldering technic that could allow me to get better results ?

(I was thinking something like, apply the solder on the pcb without the wire, then reflow the solder with the soldering station and, while the solder is hot and liquid, put the wire)

Answer 1

Ideally, you should avoid finding yourself in this situation. Using appropriate connectors or atleast making sure you have enough room to comfortably attach the wires on the pads is a useful thing to do. You should certainly try to fix the problem more robustly if you want to produce or manufacture the thing.

For a one off thing, though, hot glue should work. There is a technique called potting, which using a different material, which does essentially what you imagine hot glue will do. Typically, potting is used to reduce stress at connector/solder joints and prevent cables from flapping around and so on. The potting material is better at doing this if the signals are especially sensitive in some way, since hot glue isn't a material explicitly chosen for it's insulating/dielectric properties. You should give it a go, though, for most applications it's probably insulating enough.

Answer 2

You can use Milk of Magnesia as a temporary solder-stop.

edit: Milk of magnesia will protect it during soldering, as temporary solder mask. You really should be soldering the wire so that nothing moves. If the strands are moving, it's a poor solder joint and will eventually fail. If you absolutely can't get them to stay still, then use a harder epoxy than hot glue. I like RTV but a cured non-conductive epoxy would be better still.