Solder joint comes off? Woof.
Best to think of cleaning flux this way:
Flux is sticky and viscous. Like grease. It's difficult to get all of it unless you dissolve it in something else first.
IPA makes for a good solvent...isopropyl alcohol, not the beer. That'd compound the issue methinks...
Electronics contact cleaner will work much faster, but it will also evaporate much more quickly, leaving all that flux it dissolved evenly spread across the surface of the board.
So, really, what you have to do is first dissolve the flux in another medium, and then use the solvent to transport the flux off the board. Kim wipes work well...typically I'll throw on a little electronics cleaner, scrub gently with a toothbrush, a little IPA, scrub, throw on a dry Kim wipe, gently scrub, throw on another dry Kim wipe over the top, gently scrub. Get most the IPA off, you tend to have a clean board.
Except if its a 2 sided board, in which case the flux and solvent will seep through to the opposite side and leave unsightly patches. Haven't found a way to mitigate this yet...
