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K2 - Cleaning a completed PC board

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stan levandowski

K2 - Cleaning a completed PC board

I've been told that it is good practice to clean a completed PC board
with either acetone or denatured alcohol and a small toothbrush.

I could not bring myself to do this when I completed my KX1 - it just
seemed (at least to me) somewhat risky to be brushing a liquid with a
nylon toothbrush all over a populated board.

Now I'm faced with the same issue as I begin my K2. I want to do
"everything right" because this K2 is going to be my "baby" -- but.....

So I am asking for some opinions on just what the risk/benefits are and
perhaps to get some idea as to whether this is really a practical and
useful process or a "purist" finishing touch that returns marginal bang
for the buck.

Thanks for any insights,

Stan Levandowski WB2LQF
HF QRP CW -- Doing more with less for over 50 years!
QCWA #35038 OOTC #4558 NAQCC #4740 SKCC #6488 FISTS #(Pending)
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Alan Bloom

Re: K2 - Cleaning a completed PC board

When I was working for HP/Agilent, the rule was that you NEVER clean a
board that way because of the risk of ionic contamination.

The rosin flux used in multi-core solder is normally the "mildly
activated" (RMA) type. That means it includes a moderate amount of the
acid that is used to remove the oxide coating on the metal so that the
solder can adhere.

Left-over flux on a board is not a problem because the acid is bound up
in the rosin where it can do no harm. However, if you melt the rosin
with alcohol or some other solvent, the acid is spread out over the
surface of the board. It is nearly impossible to get 100% of it off, no
matter how many times you go over it with the Q-tip.

The resulting ionic contamination can cause corrosion and, in the
presence of humidity, creates an electrical leakage path between nearby
traces.

The flux that they used in production was a water-soluble (non-rosin)
type which, while quite corrosive, could be completely removed in the
automated board-cleaning machine. Rosin flux was used in the re-work
stations but the rule was you did not attempt to clean it off.

Al N1AL

On Wed, 2010-09-08 at 13:43 -0400, stan levandowski wrote:

> I've been told that it is good practice to clean a completed PC board
> with either acetone or denatured alcohol and a small toothbrush.
>
> I could not bring myself to do this when I completed my KX1 - it just
> seemed (at least to me) somewhat risky to be brushing a liquid with a
> nylon toothbrush all over a populated board.
>
> Now I'm faced with the same issue as I begin my K2. I want to do
> "everything right" because this K2 is going to be my "baby" -- but.....
>
> So I am asking for some opinions on just what the risk/benefits are and
> perhaps to get some idea as to whether this is really a practical and
> useful process or a "purist" finishing touch that returns marginal bang
> for the buck.
>
> Thanks for any insights,
>
>
> Stan Levandowski WB2LQF
> HF QRP CW -- Doing more with less for over 50 years!
> QCWA #35038 OOTC #4558 NAQCC #4740 SKCC #6488 FISTS #(Pending)
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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Don Wilhelm-4

Re: K2 - Cleaning a completed PC board

In reply to this post by stan levandowski

Stan,

Do NOT attempt to remove the flux - it is not conductive and will cause
no problems, even though it may look slightly "messy".
In fact, attempts at removing flux can result in unanticipated
problems. If the flux residue plus solvent gets under connector headers
or relays, or even ICs, it will not be completely removed and the
residue left in those places can later make conductive paths where they
should not be. I did work on one K1 that had been completely ruined by
an attempt at removing the flux.

If you must clean a board, do it in small areas - do NOT flood the board
with the solvent (yes, use de-natured alcohol, acetone can etch plastic
components) - apply the solvent sparingly in a small area at a time, and
blot it off with a paper towel. Alcohol attracts water from the air
rapidly, and the reduced temperature of the board caused by rapid
evaporation will cause the water to condense on the board - wipe it up
too, but do not apply power until it has completely dried.
If you feel you must remove the flux, build up a small board (like the
RF Probe from the parts provided in the K2 kit), and practice your flux
removal technique on that first so you know what to expect.

If you want to avoid a large flux residue, use a solder with a mildly
reactive flux, such as Kester 285. While Kester 44 is much better know,
it has a highly reactive flux and leaves much more residue than the
mildly reactive flux. Save the highly reactive flux for soldering jobs
that have noticeable oxidation on the surfaces.

73,
Don W3FPR

On 9/8/2010 1:43 PM, stan levandowski wrote:

OZ2BRN Brian Lodahl

Re: K2 - Cleaning a completed PC board

Hi Stan WB2LQF,

IN the event that you may decide to do an isolated cleaning of some area
of flux that is particularly nasty, then I can definately reccomend this
channel on Youtube - it contains loads of good instructions and
step-by-step guides to proper work on and around PCB's and components:

http://www.youtube.com/user/SolderingGeek#p/u

In regards to the cleaning of a PCB, as also Don W3FPR was so correctly
pointing out, DO NOT splash this all over your board like its' a bottle
of after shave, but rather deposit in small areas with only trace
amounts of alcohol at the time. You may find a cotton swab a suitable
and more gentle alternative to a brush.

You can see in an example here (timestamp 3:58) how this can be performed.
http://www.youtube.com/user/SolderingGeek#p/u/37/G14rFgAfwXk

73 -
Brian OZ2BRN

Den 08-09-2010 20:22, Don Wilhelm skrev:

> Stan,
>
> Do NOT attempt to remove the flux - it is not conductive and will cause
> no problems, even though it may look slightly "messy".
> In fact, attempts at removing flux can result in unanticipated
> problems. If the flux residue plus solvent gets under connector headers
> or relays, or even ICs, it will not be completely removed and the
> residue left in those places can later make conductive paths where they
> should not be. I did work on one K1 that had been completely ruined by
> an attempt at removing the flux.
>
> If you must clean a board, do it in small areas - do NOT flood the board
> with the solvent (yes, use de-natured alcohol, acetone can etch plastic
> components) - apply the solvent sparingly in a small area at a time, and
> blot it off with a paper towel. Alcohol attracts water from the air
> rapidly, and the reduced temperature of the board caused by rapid
> evaporation will cause the water to condense on the board - wipe it up
> too, but do not apply power until it has completely dried.
> If you feel you must remove the flux, build up a small board (like the
> RF Probe from the parts provided in the K2 kit), and practice your flux
> removal technique on that first so you know what to expect.
>
> If you want to avoid a large flux residue, use a solder with a mildly
> reactive flux, such as Kester 285. While Kester 44 is much better know,
> it has a highly reactive flux and leaves much more residue than the
> mildly reactive flux. Save the highly reactive flux for soldering jobs
> that have noticeable oxidation on the surfaces.
>
> 73,
> Don W3FPR
>
> On 9/8/2010 1:43 PM, stan levandowski wrote:
>> I've been told that it is good practice to clean a completed PC board
>> with either acetone or denatured alcohol and a small toothbrush.
>>
>> I could not bring myself to do this when I completed my KX1 - it just
>> seemed (at least to me) somewhat risky to be brushing a liquid with a
>> nylon toothbrush all over a populated board.
>>
>> Now I'm faced with the same issue as I begin my K2. I want to do
>> "everything right" because this K2 is going to be my "baby" -- but.....
>>
>> So I am asking for some opinions on just what the risk/benefits are and
>> perhaps to get some idea as to whether this is really a practical and
>> useful process or a "purist" finishing touch that returns marginal bang
>> for the buck.
>>
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>

AC7AC

Re: K2 - Cleaning a completed PC board

CONTENTS DELETED

The author has deleted this message.

myles landstein

Re: K2 - Cleaning a completed PC board

I don't use alcohol , I use specific PCB safe cleaners.

Digi Key , Mouser etc etc sell cleaners 'safe' for various types of boards .

Some I've used in the past are made by Chemtronics

Always make sure what ever your using isn't going to react with the parts or the plastic , always test a tiny drop in a safe area

Also a good idea to have some compressed air to both clean and dryout things....

Lastly make sure when you are spraying or wiping air or chemicals that you are ESD safe

good luck

On Sep 8, 2010, at 5:52 PM, Ron D'Eau Claire wrote:

> Too much solder, usually using solder too big in diameter, is one of the
> fastest ways to end up with excess flux all over the place.
>
> For PC board work I rarely use anything larger than 21 gauge (0.032") and
> often solder half that size (0.015").
>
> Ron AC7AC
>
>
> ______________________________________________________________
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OZ2BRN Brian Lodahl

[K2] #6936: IF AGC Amp SMT1 missing from RF board inventory check

In reply to this post by AC7AC

Hi gents,

Done with the inventory check of the RF board, all there EXCEPT ... I
cannot seem to find the SMT1, IF-AGC amp, that is SMT mounted on a
daughter board. I do however have the two pcs 4-pin headers that go
along with it, and the other small SMT component (the pin diode). So
far, so good.

Now i have experience now a few times during inventory check that
special parts can be "hidden" some funny places in all the packaging
material, and this is not really described very well in the manual, so
are there anyone besides me that have been missing this one part and
found it in a perculiar place in the all the envelopes ?

Please advise, so I may have to avoid calling up Elecraft and request
this one without reason - HI HI

73-
OZ2BRN Brian
K2 #6936

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Guy, K2AV

Re: [K2] #6936: IF AGC Amp SMT1 missing from RF board inventory check

Hi, Brian.

Always go through ALL the components at the beginning. There should
be no unopened, un-inventoried envelopes when you start construction.
Personally, I've never seen loose components outside envelopes from
Elecraft. You could have an entire envelope that got moved somehow.
That would be caught by missing an envelope's worth of stuff. That
said...

Nobody at Elecraft will be bothered that you did not search the Queen
Mary with a magnifying glass before you got in touch. Particularly
since you are across the pond, get the process started early. The
post sometimes puts irritating delays on stuff. If there is a
workaround for you to let you get started anyway, based on the part
you are missing, they will tell you.

73, Guy.

On Thu, Sep 9, 2010 at 7:20 AM, OZ2BRN Brian Lodahl
<[hidden email]> wrote:

> Hi gents,
>
> Done with the inventory check of the RF board, all there EXCEPT ... I
> cannot seem to find the SMT1, IF-AGC amp, that is SMT mounted on a
> daughter board. I do however have the two pcs 4-pin headers that go
> along with it, and the other small SMT component (the pin diode). So
> far, so good.
>
> Now i have experience now a few times during inventory check that
> special parts can be "hidden" some funny places in all the packaging
> material, and this is not really described very well in the manual, so
> are there anyone besides me that have been missing this one part and
> found it in a perculiar place in the all the envelopes ?
>
> Please advise, so I may have to avoid calling up Elecraft and request
> this one without reason - HI HI
>
> 73-
> OZ2BRN Brian
> K2 #6936
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

OZ2BRN Brian Lodahl

[K2] #6936: IF AGC Amp SMT1 missing from RF board inventory check

No worries, guys. this is not yet setting me back, at least :-)

I will complete 100% the inventory check before I proceed to contact
Elecraft customer service, that is certain. It is just that I have, as
probably many of us, mistakenly been missing "stuff" until now, only to
realize that this was safely packed away in another envelope etc. And -
I must admit much to the appreciation of the Elecraft staff - this is
until now also the only thing I have found missing.

I have a little DX-pedition coming up next week anyway, visiting my
sister state-side, so I need not worry about delayed shipments overseas
etc., as I will anyway wait with the last part of the build until I
return back again.
I will in this case off course arrange for the shipment with US mail to
my temporary address in US, so that I can bring home with me the missing
part(s).

73'
Brian OZ2BRN
K2 # 6936

Den 09-09-2010 18:34, Guy Olinger K2AV skrev:

> Hi, Brian.
>
> Always go through ALL the components at the beginning. There should
> be no unopened, un-inventoried envelopes when you start construction.
> Personally, I've never seen loose components outside envelopes from
> Elecraft. You could have an entire envelope that got moved somehow.
> That would be caught by missing an envelope's worth of stuff. That
> said...
>
> Nobody at Elecraft will be bothered that you did not search the Queen
> Mary with a magnifying glass before you got in touch. Particularly
> since you are across the pond, get the process started early. The
> post sometimes puts irritating delays on stuff. If there is a
> workaround for you to let you get started anyway, based on the part
> you are missing, they will tell you.
>
> 73, Guy.
>
> On Thu, Sep 9, 2010 at 7:20 AM, OZ2BRN Brian Lodahl
> <[hidden email]> wrote:
>> Hi gents,
>>
>> Done with the inventory check of the RF board, all there EXCEPT ... I
>> cannot seem to find the SMT1, IF-AGC amp, that is SMT mounted on a
>> daughter board. I do however have the two pcs 4-pin headers that go
>> along with it, and the other small SMT component (the pin diode). So
>> far, so good.
>>
>> Now i have experience now a few times during inventory check that
>> special parts can be "hidden" some funny places in all the packaging
>> material, and this is not really described very well in the manual, so
>> are there anyone besides me that have been missing this one part and
>> found it in a perculiar place in the all the envelopes ?
>>
>> Please advise, so I may have to avoid calling up Elecraft and request
>> this one without reason - HI HI
>>
>> 73-
>> OZ2BRN Brian
>> K2 #6936
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>