Good to know, as I am a big fan of JB Weld.
Never thought of using it on a circuit board though.  That's a bit of over kill.  
I always used regular 2 part epoxy, which is not conductive, and you can see what you are doing.

I never woulda thought about it. Bear trap identified  and avoided. Thanks.  I bought some high temp epoxy, like the stuff you see the
Not serviceable
Electronic stuff encased in. Failed to save the engine, but, oooh well.
I use it in places where the Devcon five minute or JB don't feel right.

I patched a sealing surface on a frac pump with JB weld. All our frac trucks were on jobs or down fluid ends removed and in a machine shop, being repaired. I looked at the washed out spot, told the boss I could fix it, cleaned it up, put the JB in, built dams and supports, hung a drop light in it, and nobody messed with it. I figure they figured itd fail without them messing with it. Frac pumps run for hours and put up pressure sufficient to fracture the formation, pumping in a mix of sand and chemicals, the sand props the cracks open, allowing for the flow of oil from the formation, back to the casing, pump, all that ,,
And, it held up. Boss never took me aside and said thanks. Co-workers  still a buncha jerks... I never liked working for big companies. Too much favoritism, not near enough merit based decision making.. When oil crashed, layoffs came, they kept the do nothing butt kissers. And, eventually Eddie Childs baby, the Western company, was gone.

If you don't have some JB quickset, might consider it. And Devcon five  minute, in the syringe, too expensive and it's not as easy to adjust the ratio. Sometimes I want it hot, fast and hard, ( Hmmm, in my head, that didn't sound like it looks ) and, some applications I want it to not crack readily, a slower set, I think, leaves a cured lump that's not so rigid. So, I get the bottles.

The local auto glass shop has some nylon sticks they push the black goo they use with. Get a couple, shape the ends up, stir , apply, wipe, what don't wipe, peels. I've got two, one I've had about thirty five years..  Don't use cardboard, it soaks stuff out of the epoxy.. What, IDK, but why risk it? A clipboard, once it's got a coat on it, piece of plexiglass , stuff it behind the tool box..

YeAh, I don't feel good enough to get out, so, you're being punished.