Kester specifically says that rosin residue removal is for cosmetic
considerations. Here's the exact quote:
"Rosin flux residues are non-conductive and non-corrosive. Under normal
circumstances they do not have to be removed from a printed circuit
assembly. Rosin residue removal would be for cosmetic considerations. In
an environment where the working temperature of the assembly will exceed
200°F the rosin residues will melt and become conductive, in these
situations flux removal is required."
https://www.kester.com/knowledge-base/faq#46137-rosin-flux-removal-the-question-that-frequently-comes-up-is-do-rosin-flux-residues-need-to-be-removed
Again I recommend that you not attempt to remove the flux residue unless
you have the technical means to ensure that all traces of it are
completely removed.
Alan N1AL
On 1/1/2022 2:01 PM, Eric Garner wrote:
>The only reason for removing flux is purely cosmetic
That isn't accurate. Even modern no-clean fluxes can cause corrosion
and current leakage if left in place under certain conditions If
leakage is a concern, you can specify a surface resistivity level and
the boards can be ultrasonic washed or double DI washed to meet that
criteria.
Eric KI7LTT
On Sat, Jan 1, 2022, 11:16 AM Alan Bloom <n...@sonic.net> wrote:
Another problem with cleaning flux is ionic contamination. The
activator in the flux, which is necessary to get the solder to
stick, is
acidic. As long as the flux is left alone, the ionic
contamination is
trapped in the rosin where it can do no harm. But when you
dissolve it
with alcohol or another solvent is is spread over the surface of the
board, unless you do a VERY thorough job of cleaning it off. That
can
cause electrical leakage between circuit nodes and potentially
corrosion.
The only reason for removing flux is purely cosmetic. When I was at
HP/Agilent the rule in production and service was that any flux
remaining on the board due to re-work or repair was just left in
place.
Alan N1AL
On 1/1/2022 3:25 AM, CUTTER DAVID via Elecraft wrote:
> Ted
> If the residue is clear, don't bother, you might create more
damage than you realise (ESD). If the residue is brown, you've
been using the wrong solder. If you really feel the desire for
aesthetics then you can can brush it with IPA, but beware ESD if
there are sensitive components on board. Also beware some
components can dissolve in some cleaners, eg old style polystyrene
capacitors.
>
> 73 and HNY
> David G3UNA
>
>> On 31 December 2021 at 20:52 eda...@aya.yale.edu wrote:
>>
>>
>>
>>
>> Is there a consensus among builders of the traditional kits
(K1, K2, etc)
>> about the best way to remove solder flux from a completed
circuit board?
>> Some Internet sites recommend acetone, others say isopropyl
alcohol. A few
>> tout their own product without saying exactly what it is. I
remember
>> reading someplace that one or the other of those will clean the
flux but
>> could also cause damage by being absorbed into components.
Yes, I know this
>> is all purely cosmetic but if it can be done safely I'd like to
try it on
>> the next kit. Suggestions?
>>
>>
>>
>> Thanks,
>>
>>
>>
>> Ted, KN1CBR
>>
>>
>>
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