cleaning pcbs

[jarthel]

I've read people recommend isopropyl alcohol (99%) to clean their PCBs.

I do not think those are available locally. I've only seen the "rubbing" alcohol stuff. Are they substitutes are the available from the "corner" shop (i.e. easily available without resorting to percy and other similar shops)?

Thank you.

[dnsey]

Don't know about Aus, but here in the UK most pharmacies carry IPA. If you don't see it, ask!

[Stocker]

My absolute favorite is semiconductor grade 99.999... % pure isopropanol, but that is more expensive. If you can find 90% rubbing alcohol, it should work. The price is right... try it and see if it's good enough for you.

[jarthel]

Originally posted by dnsey
Don't know about Aus, but here in the UK most pharmacies carry IPA. If you don't see it, ask!

the usual ones I can see are 640mL/L solution. but I'll ask if they have a stronger solution. thank you.

[jarthel]

Originally posted by Stocker
If you can find 90% rubbing alcohol, it should work. The price is right... try it and see if it's good enough for you.

how do I know if it's good enough?

thanks

[mrshow4u]

You can get 99% Isopropyl from the chain drug stores. It's stocked right along with the 70% rubbing alcohol. If your drug store doesn't have it, check a medical supply center. You can get good swabs there too. 99% Isopropyl works great. Don't soak things too long. Things like rubber sealed electrolytics etc., might not fair too well.

[poobah]

It depends on your boards of course... but good ole soap and water works wonders. Pots, switches, and tranformers can make this impossible. But the vast majority of boards built these days are cleaned with water. Follow this with a good soak in RO water and 1/2 hour in the oven at it's lowest setting... ~150-160 F.

Just what type of board?

Ethyl Alcohol is also very good... your local hardware shop should have it cheap... "De-natured Alcohol". It's just ethanol with some poisons added so the wookiees won't drink it.

[jarthel]

i haven't used alcohol on pcbs before so the question might sound ignorant.

I can use alcohol to clean the pcb before and after soldering components. is this right?

thanks again

[poobah]

Yes!

[wrenchone]

The best rinse will depend on what flux you use. I insist on using rosin core flux, as I find the fumes from water soluble and "no clean" fluxes to be a lot more irritating. For rosin core flux, 90% isopropanol works quite well, and is pretty cheap ($1-2 per quart in the U.S). One usually finds it right next to the 70% isopropanol "rubbing alcohol" in stores that stock it.
I don't rinse until after everything is soldered in order to limit the solvent exposure for the components. Isopropanol is on the approved list of solvents for electrolytic capacitors.Evenif it gets through the end seals, it doesn't damage the works inside. Don't use chlorinated solvents under any circumstances. They clean off flux residudes very well, but they also seep into the end seals of electrolytics and cause the insides to disintegrate over time. Acetone is also not a good idea, as it eats a lot of plastics, especiallly polystyrene.
When you do rinse, give the board a good flush-down to carry away all the flux. Use something like an old toothbrush to loosen up stubborn deposits. The best approach is to use a pie pan or a poly container full of alcohol for the main scrub-down, then a final flush with clean, uncontaminated alcohol, so there are no residudes left behind. If you are stingy with the solvent, you just end up with a sticky circuit board.