[volt-nuts] Best cleaning procedure for precision cirquits

Alan Scrimgeour scrimgap at blueyonder.co.uk
Sat Oct 9 11:49:59 UTC 2010


In my experience IPA doesn't dissolve all flux residue, leaving an off white 
powdery material not due to IPA impurities. Acetone dissolves the lot, but 
can damage some plastics.
I've been looking into Vapour Degreasing for the first time in many years 
and am surprised to find it is virtually a thing of the past. 3M sell some 
'green' fluorinated solvents, but I'd imagine they're horrendously 
expensive. Flammable solvent degreasing would be just too dangerous indoors! 
Methylene Chloride is still readily available for some reason, but it's a 
potent paint stripper/plastic destroyer, so that's out for electronics. I 
was hoping at least there might be some small vapour degreasing tanks at 
scrap prices, but no sign of those either.
I'd be concerned about using water based cleaning on very sensitive 
circuits, as described in a recent post. Although I wouldn't expect it to 
cause any problems with PTFE, it may affect the component package.
A long bake after cleaning might be a good idea however you clean..

Alan


----- Original Message ----- 
From: "Robert Atkinson" <robert8rpi at yahoo.co.uk>
To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
Sent: Saturday, October 09, 2010 9:38 AM
Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits


Hi,
Pure (99%+) IPA won't leave a residue. It my be dissolving dirt or a 
coating. For hermetic compounets a clean with dish washing soap and warm 
water in an ultrasonic cleaner, (followed by a second in fresh solution for 
very dirty parts), then de-ionised water and finally IPA is excellent. If 
the components can stand it (metal, glass, teflon, epoxy) pure acetone is 
one of the best finishing agents. Don't leave it to soak though.
For non-ferrous metal parts add some ammonia solution to the first mix.

Robert G8RPI.

--- On Sat, 9/10/10, Randy Evans <randallgrayevans at yahoo.com> wrote:

From: Randy Evans <randallgrayevans at yahoo.com>
Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits
To: jfor at quik.com, "Discussion of precise voltage measurement" 
<volt-nuts at febo.com>
Date: Saturday, 9 October, 2010, 4:04

I will be using teflon stadoffs but I am using range resistors from an old
Keithley 414 Picoammeter that were very dusty and dirty and I need to clean 
them
prior to using them again. i did clean them with isopropyl alcohol but it 
left
a residue on them that I want to clean off.

Randy



----- Original Message ----
From: J. Forster <jfor at quik.com>
To: Discussion of precise voltage measurement <volt-nuts at febo.com>
Sent: Fri, October 8, 2010 6:23:36 PM
Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits

Picoamp stuff is usually done with Teflon standoffs or guarded PCBs,
preferably the former.

FWIW,

-John

===============


> Separate from cleaning flux off a board, what is the best solvent/cleaning
> agent for removing dirt and grime from a board and compnents for the
> lowest
> leakage currents; e.g., for a picoamp measurement system with very high
> value
> reistors?
>
> Thanks,
>
> Randy Evans
>
>
>
> ----- Original Message ----
> From: Chuck Harris <cfharris at erols.com>
> To: Discussion of precise voltage measurement <volt-nuts at febo.com>
> Sent: Mon, September 27, 2010 3:18:27 PM
> Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits
>
> I don't like denatured alcohol. They add a little methyl
> alcohol, which is very poisonous for skin contact, ingestion,
> and breathing. Also, it is rather corrosive.... and worst of
> all, it leaves behind a white powder when it dries.
>
> If you really want to use ethanol (the base for denatured alcohol),
> buy it from the liquor store.
>
> Aerosol cans of "compressed air" are really filled with anything
> but air. They used to be filled with freon, and then later butane,
> NO2, and finally CO2.
>
> -Chuck Harris
>
> Andreas Jahn wrote:
>> Hello all,
>>
>> thanks for the many informations and proposals.
>>
>>> From Your proposals I think the most interesting for my capabilites
>>> are:
>>
>> - the isopropylene alcohol
>> - and the "Kontakt LR" cleaner
>>
>> both for the last (3rd?) cleaning stage since the denatured alcohol is
>> much cheaper.
>>
>> And I have learned that I should get some aerosol cans with compressed
>> air for drying the cirquit.
>>
>> with best regards
>>
>> Andreas
>>
>>
>>
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