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Old 14th Sep 2019, 12:55 am   #1
cjacek2000
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Question Spraying PCB boards with alcohol

Hello all,
Currently cleaning up a mid 80's VCR. There was a large amount of smelly dust/dirt on the PCB board under the power supply. I cleaned most of that up with a brush, vacuum, spray duster and some 99% isopropyl alcohol and cotton swabs but there is still some caked in gunk left. It would take me forever to reach all the small / tight spaces with cotton swabs. Is it OK and safe (without removing or unplugging the PCB) to fill up a spray bottle with 99% alcohol and spray the hell out of the PCB, tilting the recorder (and PCB) in such a way that hopefully the grime just dissolves and flows away? Or should I just leave it alone?
Thanks!
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Old 14th Sep 2019, 1:00 am   #2
cjacek2000
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Default Re: Spraying PCB boards with alcohol

Maybe something like this for example:
https://www.amazon.ca/MG-Chemicals-I...8419102&sr=8-5

.... or this:
https://www.amazon.ca/MG-Chemicals-I...8419386&sr=8-7
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Old 14th Sep 2019, 1:11 am   #3
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Default Re: Spraying PCB boards with alcohol

sorry, I also found these:
https://www.mgchemicals.com/products...onic-cleaners/
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Old 14th Sep 2019, 2:18 am   #4
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Default Re: Spraying PCB boards with alcohol

Isopropyl alcohol can be a little aggressive on some surfaces and components, I seldom use it. The safest thing to clean populated pcb's with is CRC's CO contact cleaner or a similar product made by motortec here at least called circuit board and contact cleaner. It won't damage plastic surfaces, it is safe on all electronic components, yet it will remove residual fluxes:

https://www.ebay.com/itm/CRC-CO-Elec...AAAOSweW5VQNHT

There should be an equivalent product where you are.
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Old 14th Sep 2019, 5:59 am   #5
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Default Re: Spraying PCB boards with alcohol

The active ingredient in CRC CO Contact Cleaner is isopropyl alcohol (IPA).

Alan
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Old 14th Sep 2019, 8:37 am   #6
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Default Re: Spraying PCB boards with alcohol

I’ve used IPA for years on PCB’s and other things that needed cleaning, we use it at work too, along with another product called Ultrasolve, both good at shifting flux residue. Normally we then put the washed PCB in an oven for 12 hours, but that would normally only be if we were then covering it in conformal coating, so an hour at 50 degrees would probably be enough to dry off any remaining alcohol.

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Old 14th Sep 2019, 12:16 pm   #7
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Default Re: Spraying PCB boards with alcohol

Quote:
Originally Posted by ajgriff View Post
The active ingredient in CRC CO Contact Cleaner is isopropyl alcohol (IPA).

Alan
Sorry I had thought the components in CRC's CO contact cleaner were the same as another product I use, that I could not find on a search so I suggested the CRC product, so please ignore my reference to it. The one I am using contains trichloroethylene which has become unpopular.
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Old 14th Sep 2019, 2:39 pm   #8
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Default Re: Spraying PCB boards with alcohol

Please don't laugh, we used to refurb 200+ rear projection tvs (crt) a week and I came up with the crazy idea of washing boards in warm soapy water, they got heavily contaminated in coolant from the six inch screens (colour) when a leak took place. Never got a set back with corrosion faults, left to soak overnight. I was a little sceptical with line output stages, up to 30kv but after warming gently for a day or two they were fine. Obviously, signal stages were more tolerant of a touch of damp but as you will know it's fatal in line stages. Even then I had been in the trade many years, (two stations in b\w) had worked on top end gear but I still got laughed at for doing this. Using alcohol always scared me, as the idiots do who sprayed WD40 on anode caps. True, electricity and water do not mix, unless its hydro-electric or me washing boards in the sink, but as always, take care.
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Old 14th Sep 2019, 2:54 pm   #9
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Default Re: Spraying PCB boards with alcohol

alcohol is certainly the way for most boards, never had a problem except for residue not being flashed off properly before applying power; its conductive.

If in doubt (or in a hurry!) I follow the IPA rinsing with a gentle prolonged wave from a hot air gun. In winter I put the board or device on a table over the convector heater.

Some stubborn gunk is water soluble (eg cigarette deposits, beer/coffee spills or metal cutting emulsion) so in extreme cases I soak it in hot water with fairy liquid. Nothing with a transformer on, btw, as it can leach well into the windings and stay there.
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Old 14th Sep 2019, 3:35 pm   #10
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Default Re: Spraying PCB boards with alcohol

I always found IPA left a faint whitish residue on the varnished copper side of a PCB, and also removed the component references on Thorn boards! I use Servisol De-Flux as it seems less harsh. We used to use 1.1.1 Trichloroethane in the workshop which meant on a winters' day with the heating on and the doors closed we found it difficult to focus on the job in hand after using it...
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Old 14th Sep 2019, 4:38 pm   #11
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Default Re: Spraying PCB boards with alcohol

Fluke meter service manuals from the eighties recommend cleaning printed circuit assemblies using a soft brush and de-ionised water or isopropyl alcohol followed by blow drying plus baking at a low temperature. There are, of course, warnings about removing LCDs and taking care with switch contacts.

Alan
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Old 14th Sep 2019, 6:31 pm   #12
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Default Re: Spraying PCB boards with alcohol

Quote:
Originally Posted by ajgriff View Post
The active ingredient in CRC CO Contact Cleaner is isopropyl alcohol (IPA).
Alan
I looked up the SDS for that product on line and the one I found did not include IPA http://docs.crcindustries.com/msds/2016M.pdf.

The choice of the "best" cleaning agent really depends a lot on the nature of the soiling material. But working on the basis of trying the most innocuous agent first, I'd tend to go with IPA. But whenever the subject of cleaning crops up, people usually have their own favourite strategies.

B.
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Old 14th Sep 2019, 7:22 pm   #13
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Default Re: Spraying PCB boards with alcohol

Quote:
Originally Posted by Bazz4CQJ View Post
Quote:
Originally Posted by ajgriff View Post
The active ingredient in CRC CO Contact Cleaner is isopropyl alcohol (IPA).
Alan
I looked up the SDS for that product on line and the one I found did not include IPA http://docs.crcindustries.com/msds/2016M.pdf.

B.
That's interesting. The CRC contact cleaner sold here in the UK, by RS amongst others, does contain IPA. See attached Safety Data Sheet.

The difference seems to be the 'CO' in the product name. I wonder if this is down to the variations in regulatory standards across the globe? It may be that the petroleum based product is available in Canada, as it presumably is in Australia (originally highlighted by Argus25).

Alan
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Old 14th Sep 2019, 8:05 pm   #14
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Default Re: Spraying PCB boards with alcohol

Mmm...could be any number of explanations. IPA on its own is a pretty poor degreasing agent, but that mixture of IPA with alkanes would be better, but there will be some pros and cons somewhere. In an industrial setting, you might have a selection of cleaning agents for different purposes, but at home, I think that people are often hoping to find the "one size fits all" solution.

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Old 14th Sep 2019, 9:19 pm   #15
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Default Re: Spraying PCB boards with alcohol

We used to use IPA for cleaning boards at Plessey in the 1970's.

When the plumber fixing my mother's gas boiler inadvertently managed to soak its printed circuit board, I lent him her old Electrolux vac, used on "Blow". The blast was strong enough to dispel all the water from under flush-mounted components such as DIL ICs and capacitors, and it suffered no ill-effects.
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Old 15th Sep 2019, 10:18 am   #16
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Default Re: Spraying PCB boards with alcohol

Quote:
Originally Posted by Argus25 View Post
Quote:
Originally Posted by ajgriff View Post
The active ingredient in CRC CO Contact Cleaner is isopropyl alcohol (IPA).

Alan
Sorry I had thought the components in CRC's CO contact cleaner were the same as another product I use, that I could not find on a search so I suggested the CRC product, so please ignore my reference to it. The one I am using contains trichloroethylene which has become unpopular.
Certainly no need for an apology. I've now looked at the data sheets for the US, European, Canadian & Australian versions of CRC Contact Cleaner and they all appear to have quite different active ingredients. As a potential user (rather than an organic chemist) of such products I'm thoroughly confused.

Alan
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Old 15th Sep 2019, 4:30 pm   #17
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Default Re: Spraying PCB boards with alcohol

It's not uncommon for goods sold in different territories under the same brand name to have different formulations, due to things like climate as well as different legal requirements. There were several cases in the 1980's where UK companies were able to prevent grey imports of stuff having the same brand name (not fakes, but made by foreign subsidiaries of the UK company for their local markets) because the imported stuff wasn't suitable for use in the UK. Canadian Castrol GTX motor oil comes to mind. Reflecting the temperature extremes of the Canadian climate, Canadian GTX was only manufactured in specific summer and winter formulations rather than the single multigrade product sold in the UK, and its use in the UK could have resulted in engine damage.
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Old 15th Sep 2019, 7:10 pm   #18
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Default Re: Spraying PCB boards with alcohol

In times-past I dunked marine-band walkie-talkies [with batteries removed] that had been dropped in the sea into a bath of Ethanol, followed by a few days in a zero-humidity tank.

If you got there in time, it was good-enough to stop the speaker voice-coil/magnet rusting up.
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Old 15th Sep 2019, 7:34 pm   #19
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Default Re: Spraying PCB boards with alcohol

Quote:
Originally Posted by Welsh Anorak View Post
I always found IPA left a faint whitish residue on the varnished copper side of a PCB, and also removed the component references on Thorn boards! I use Servisol De-Flux as it seems less harsh. We used to use 1.1.1 Trichloroethane in the workshop which meant on a winters' day with the heating on and the doors closed we found it difficult to focus on the job in hand after using it...
Beat me to it on the thorn boards glyn, learnt that the hard way on the 3000 series refurbishing crispy power supply modules, not sure tric is available anymore, all the really good stuff is banned or carcinogenic, i used a water based cleaner on the 2000 restoration after removing anything likely to be damaged.
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Old 16th Sep 2019, 9:32 am   #20
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Default Re: Spraying PCB boards with alcohol

I have found while fixing up and restoring a Roberts R300 that Kontakt WL ('Wash Spray') which I believe is IPA based can really throw out a variable capacitor. Not in the metal vanes but under the mica type washer of the trimmers. Just a tiny amount ran into there and the tuning was way off for about 15 minutes until I had sucked it all up with the capillary action of a piece of kitchen paper.

So the same might apply to anything else with tuned circuits.
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