Hello!
Friend of mine is working on this amplifier board to swap few power supply capacitors.
White deposits on soldering was a surprise for him and I.
What could be the reason? ISP alcohol to the rescue? or let it be the way it is?
Thanks.
Friend of mine is working on this amplifier board to swap few power supply capacitors.
White deposits on soldering was a surprise for him and I.
What could be the reason? ISP alcohol to the rescue? or let it be the way it is?
Thanks.
It could be a no-clean type of flux. Those, in theory, should not react with much of anything, but they can still leave a mess. There's certainly no harm in cleaning it up. Use a flux remover such as the one by MG Chemicals or Flux-Off by Chemtronics. Spray on the flux remover, give the board a good scrub with a stiff antistatic brush. Then rinse off the remover (and dissolved flux) with water. Dry the board in an oven for 10-15 minutes at 60-80 ºC.
If it is no-clean flux you're not likely to get anywhere with IPA. If it's RMA flux the IPA will likely get rid of it.
Tom
If it is no-clean flux you're not likely to get anywhere with IPA. If it's RMA flux the IPA will likely get rid of it.
Tom
If you are using 70% IPA to clean up flux, it's very common to see white deposits on the board, as the IPA with extra water won't clean up all the residue. Using 91% IPA should clean up that last reluctant bit left behind. Use plenty of IPA, and mop it up with a paper towel to get rid of the last remnants of flux. Being stingy with the IPA will likely leave you with a sticky board.
It's likely OK.
I use acetone and a toothbrush to clean flux. As was stated, the water in rubbing alcohol leaves a white haze.
If you use a toothbrush, don't use a clear one. They generally melt in acetone.
For heavy concentrations of flux (this isn't), you can lay a paper towel on the board and brush through the paper towel. The towel will soak up the flux and other contaminants. Brush one more time if necessary after removing the paper towel (while still wet. don't leave on the board to dry after brushing).
I use acetone and a toothbrush to clean flux. As was stated, the water in rubbing alcohol leaves a white haze.
If you use a toothbrush, don't use a clear one. They generally melt in acetone.
For heavy concentrations of flux (this isn't), you can lay a paper towel on the board and brush through the paper towel. The towel will soak up the flux and other contaminants. Brush one more time if necessary after removing the paper towel (while still wet. don't leave on the board to dry after brushing).
FWIW the first ingredient in MG's flux remover is ethanol.
Seriously, though. Just swing by your local electronics place and get a can of flux remover. Or order it from Mouser/Digikey. Only snag is that it can only ship by ground shipping.
For any flux remover, clean the remover and dissolved flux off with water and dry.
Tom
Seriously, though. Just swing by your local electronics place and get a can of flux remover. Or order it from Mouser/Digikey. Only snag is that it can only ship by ground shipping.
For any flux remover, clean the remover and dissolved flux off with water and dry.
Tom
Acetone is a bad, bad idea for polystyrene caps - it will melt them. Chlorinated solvents are a bad, bad idea for electrolytic caps - it will eat them alive (unpredictably - a ticking time bomb) from the inside out.
A lot of the commercial flux cleaners use technical-grade hexane (you get all the isomers), so cleaning off the flux remover with water will likely curdle the flux dissolved in the hexane and leave a sticky mess, which can then be cleaned off with IPA like ya shoulda done in the first place.
A lot of the commercial flux cleaners use technical-grade hexane (you get all the isomers), so cleaning off the flux remover with water will likely curdle the flux dissolved in the hexane and leave a sticky mess, which can then be cleaned off with IPA like ya shoulda done in the first place.
Gill T - the brown gunk looks like rosin flux residue, not corrosion - IPA and a stiff brush will fix that up quick.
30 years of acetone and no damage to any electrical components. Polystyrene caps are only very rarely used in car amps.
So in general, is one safe in submerging boards in a bath of >90 IPA or ethanol and letting them soak? I mean really immersed.
Perry -
That may be fine for car amps, but amps using polystyrene eq caps will be damaged, like in any preamp or integrated amp with a good RIAA section.
That may be fine for car amps, but amps using polystyrene eq caps will be damaged, like in any preamp or integrated amp with a good RIAA section.
This thread was about amplifiers. For amplifiers, I've tried virtually everything as a cleaner for flux (trying to reinvent the wheel when I was just getting started) and for flux on amps, I have found nothing better. It contains no water (not true for rubbing alcohol), which takes time to evaporate (especially when it flows under large capacitors). It evaporates more quickly than any other solvent that I've tried.
It also works very well to remove the carbon left behind when FETs fail and to remove heatsink compound.
It's not for every application and if you get it on the faceplate of a head unit, it will be damaged. One more place it's not safe is on the heatsinks of PPI amps. It will damage the finish. When using strong solvents, you have to be aware of what you're doing. Alcohol is safer but not as good.
It also works very well to remove the carbon left behind when FETs fail and to remove heatsink compound.
It's not for every application and if you get it on the faceplate of a head unit, it will be damaged. One more place it's not safe is on the heatsinks of PPI amps. It will damage the finish. When using strong solvents, you have to be aware of what you're doing. Alcohol is safer but not as good.
91% IPA (available at chemists/drug stores) is just fine for rosin flux, and will also remove no-clean flux (a good idea for boards involving high voltage) with some scrubbing. My go-to electronics store also stocks 100% IPA, which is even better. I would not let acetone anywhere near one of my projects.
What part of your projects would be damaged by acetone?
Are you saying that this suggestion is harmful for the application in this thread?
Just because it's not your choice, that doesn't mean that it doesn't work perfectly well for cleaning flux, carbon/soot from amplifier boards.
Are you saying that this suggestion is harmful for the application in this thread?
Just because it's not your choice, that doesn't mean that it doesn't work perfectly well for cleaning flux, carbon/soot from amplifier boards.