Hacking a PCB: How to Remove Coating

[Jim Thompson]

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
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| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
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I love to cook with wine. Sometimes I even put it in the food.

[Jim Thompson]

Hacking a Park-Zone POS to make it work accurately, I find the PCB has
a relatively thick clear coating.

What's the best way to remove the coating without damaging components?

Thanks!

[Martin Riddle]

"Jim Thompson" <To-Email-Use-Th...@On-My-Web-Site.com> wrote
in message news:rgk1v75nbc0cj5b75...@4ax.com...

> Hacking a Park-Zone POS to make it work accurately, I find the PCB has
> a relatively thick clear coating.
>
> What's the best way to remove the coating without damaging components?
>
> Thanks!
>
> ...Jim Thompson

I've used lacquer thinner with success on the red conformal coating. The
only thing is that it will attack some plastics and wipe the numbers off
of glass diodes.

Cheers

[Tim Wescott]

On Sun, 01 Jul 2012 15:50:29 -0700, Jim Thompson wrote:

> Hacking a Park-Zone POS to make it work accurately, I find the PCB has a
> relatively thick clear coating.
>
> What's the best way to remove the coating without damaging components?
>

Try acetone. IIRC it doesn't touch most electronics components, but it
does dissolve conformal coat.

'course, if that clear coating doesn't come off with it, it's no help.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

[Jim Thompson]

Coating is clear. Looks like it was just poured over areas with
semiconductors.

[Martin Riddle]

"Jim Thompson" <To-Email-Use-Th...@On-My-Web-Site.com> wrote
in message news:d502v7trgnu8a50sa...@4ax.com...

> On Sun, 1 Jul 2012 20:07:05 -0400, "Martin Riddle"
> <marti...@verizon.net> wrote:
>
>>
>>"Jim Thompson" <To-Email-Use-Th...@On-My-Web-Site.com>
>>wrote
>>in message news:rgk1v75nbc0cj5b75...@4ax.com...
>>> Hacking a Park-Zone POS to make it work accurately, I find the PCB
>>> has
>>> a relatively thick clear coating.
>>>
>>> What's the best way to remove the coating without damaging
>>> components?
>>>
>>> Thanks!
>>>
>>> ...Jim Thompson
>>
>>I've used lacquer thinner with success on the red conformal coating.
>>The
>>only thing is that it will attack some plastics and wipe the numbers
>>off
>>of glass diodes.
>>
>>Cheers
>>
>
> Coating is clear. Looks like it was just poured over areas with
> semiconductors.
>
> ...Jim Thompson

It may be Humiseal http://www.humiseal.com/
But there are others, and they come in different chemistries, Acrylic,
Polyurethane, Silicone, UV cure

Try Acetone or Lacquer thinner in a corner and see if it softens it up.
Hopefully it's not the UV cure.

Cheers

[legg]

On Sun, 01 Jul 2012 15:50:29 -0700, Jim Thompson

<To-Email-Use-Th...@On-My-Web-Site.com> wrote:

>Hacking a Park-Zone POS to make it work accurately, I find the PCB has
>a relatively thick clear coating.
>
>What's the best way to remove the coating without damaging components?
>
>Thanks!
>
> ...Jim Thompson

It decomposes at soldering temperatures, allowing local probing and
repair with a soldering iron. It's clear, so you shouldn't have to
remove it entirely, to do what you're trying to do.

RL

[Jim Thompson]

This was poured on _after_ soldering, which was done by hand, in
China, natch.

So such a clear coat is safe to clear with an iron?

(You're right, I'm only tacking in a few extra connections, and
cutting a few traces.)

[Jim Thompson]

On Mon, 02 Jul 2012 11:50:19 -0500, legg <le...@nospam.magma.ca> wrote:

I can cut it with an X-acto knife, with a slight "rubbery" feel, so
it's hard to scrape right down to a trace.

[Chieftain of the Carpet Crawlers]

On Mon, 02 Jul 2012 10:12:29 -0700, Jim Thompson
<To-Email-Use-Th...@On-My-Web-Site.com> wrote:
...Jim Thompson
>>
>>It decomposes at soldering temperatures, allowing local probing and
>>repair with a soldering iron. It's clear, so you shouldn't have to
>>remove it entirely, to do what you're trying to do.
>>
>>RL

Good and correct advice. NO SOLVENTS.

>I can cut it with an X-acto knife, with a slight "rubbery" feel, so
>it's hard to scrape right down to a trace.
>
> ...Jim Thompson

Sadly, the best way to service it is to debug it to component level,
and only remove what you need to remove in order to change out that
component, and no solvents! Solder iron probing as mentioned above,gives
access to nodes for diagnostics.

You also have to re-seal it when done (ideally).

A good way to look at it is with a UV lamp. I can almost assure you
that is has a UV indicator in it for coverage QA.

Again, the best way is to leave as much alone as possible, use your
best diagnostic skills to define the fault, and repair only that fault
area with as little invasion into the coating as is possible/needed.

I have little bottles of it around here. We buy so much of the stuff,
entire unused cans get thrown away as it "expires".

Still good for all but new customer or "government" jobs. The stuff
even has a valid thinner, so if we adopted an analysis regimen, we could
keep what we buy and simply maintain its mix properly.

Far easier to buy more than we need and toss the extra every few
months.

I have so many mil adhesives, epoxies, coatings, conductive pastes,
gold solder... you name it. If the industry uses it, and it has a
liquid in it, it expires and gets tossed.

I could start a swap meet booth with the stuff I have collected.

I think a two part 3D printer would be cool. Then, an even harder
first item could be made.

These things are so cool! If I can think of it and put it into my CAD
app, I can "print it"! A full rendering!

The world has indeed become an amazing place.

All I have to do is ignore the dolts!

Shame you don't read my posts.

Telling you to diagnose first is the best info you could get on this.

I could send you a 30# box full of modern day 'goodies' and still have
a shop full here.

Conformal coatings? Yep.. I have likely two kinds in two formats.

Shame that you jumped onto Terrell's bandwagon. Of course, your
Zimmerman complex overtism manifested itself with a lame political stigma
where most around you are "leftist". What is it you call folks? Not
very mature, even if you want to blame them for the shithole the nation
is turning into, you can't.

Blame it on complacency in law enforcement. They are not only
complacent, but they are that way because they lack the aptitude and
competency to actually be effective at nabbing the true criminals
afflicting us.

That is why you see 5 cops harassing a teen kid in his car with dogs
and cruiser arrivals and shake downs... I mean how many hundreds of tax
dollars can the dopes waste at one time!?

Put me in office, and they will be down at the BORDER, working on the
BORDER WALL. Where the CONVICTED CRIMINALS serve their ENTIRE SENTENCE.

The world truly needs the Slipperman. You "men" are just too fucking
damned dumb.

That's why Hulk's son walks. That's why Snoop Dog walks.. That's why
Mikey Vick walks... That's why the punks in power will let assholes like
Zimmerman walk too, when the fuck should be facing federal charges.

Vick should be serving the last two years of his first of THREE prison
sentences, not being paid by the NFL (who also lost face big time that
year and since)

Very few remain who can claim to have character these days.

[Jim Thompson]

On Sun, 1 Jul 2012 22:08:43 -0400, "Martin Riddle"

Haven't been to the hardware store yet, but tried some Xylene I had on
hand... just puddles up and does nothing. I _can_ dent it _slightly_
with my fingernail.

I can get Acetone or MEK or Lacquer thinner at the hardware store. Any
ideas which to try?

[Artemus]

"Jim Thompson" <To-Email-Use-Th...@On-My-Web-Site.com> wrote in message

news:3ig6v7lpvme3a4rqd...@4ax.com...

>
> I can get Acetone or MEK or Lacquer thinner at the hardware store. Any
> ideas which to try?
>
> ...Jim Thompson

I'd try the laquer thinner first as it is a witches brew of chemicals.
www.wmbarr.com/ProductFiles/Lacquer%20Thinner%20(1605.45)%205-21-09.pdf
Art

[Chieftain of the Carpet Crawlers]

NO SOLVENTS!

Fix ONLY the area where the repair is needed to be performed.

You ask for severe headaches if you use solvents.

[Spehro Pefhany]

On Tue, 03 Jul 2012 14:40:17 -0700, the renowned Chieftain of the
Carpet Crawlers <thesli...@thebarattheendoftheuniverse.org> wrote:

>
> You ask for severe headaches if you use solvents.

You're not supposed to be inhaling that much of the solvents!

http://www.wmbarr.com/ProductFiles/Lacquer%20Thinner%20%281605.45%29%205-21-09.pdf

Inhalation Acute Exposure Effects:
Vapor harmful. May cause dizziness; headache..


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
sp...@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

[Jasen Betts]

On 2012-07-03, Chieftain of the Carpet Crawlers <thesli...@thebarattheendoftheuniverse.org> wrote:

> NO SOLVENTS!
>
> Fix ONLY the area where the repair is needed to be performed.

He's not tying to repair it.

--
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to ne...@netfront.net ---

[SoothSayer]

On Tue, 03 Jul 2012 18:36:47 -0400, Spehro Pefhany
<spef...@interlogDOTyou.knowwhat> wrote:

>> You ask for severe headaches if you use solvents.
>
>You're not supposed to be inhaling that much of the solvents!

Those are not the headaches to which I refer, toot boy.

[legg]

On Mon, 02 Jul 2012 10:12:29 -0700, Jim Thompson

<To-Email-Use-Th...@On-My-Web-Site.com> wrote:

>On Mon, 02 Jul 2012 11:50:19 -0500, legg <le...@nospam.magma.ca> wrote:
>
>>On Sun, 01 Jul 2012 15:50:29 -0700, Jim Thompson
>><To-Email-Use-Th...@On-My-Web-Site.com> wrote:
>>
>>>Hacking a Park-Zone POS to make it work accurately, I find the PCB has
>>>a relatively thick clear coating.
>>>
>>>What's the best way to remove the coating without damaging components?
>>>
>>>Thanks!
>>>
>>> ...Jim Thompson
>>
>>It decomposes at soldering temperatures, allowing local probing and
>>repair with a soldering iron. It's clear, so you shouldn't have to
>>remove it entirely, to do what you're trying to do.
>>
>>RL
>
>I can cut it with an X-acto knife, with a slight "rubbery" feel, so
>it's hard to scrape right down to a trace.
>
> ...Jim Thompson

You'll have to burn through with a hot tinned iron tip and tin the
intended contact with pre-fluxed solder. The tinning slakes off local
residue.

Once you start burning, the opacity of the film will degrade locally,
so make as many observations and notes as is possible prior to the
slash and burn.

RL

[Frnak McKenney]

On Sun, 01 Jul 2012 19:07:37 -0500, Tim Wescott <t...@seemywebsite.com> wrote:
> On Sun, 01 Jul 2012 15:50:29 -0700, Jim Thompson wrote:
>
>> Hacking a Park-Zone POS to make it work accurately, I find the PCB has a
>> relatively thick clear coating.
>>
>> What's the best way to remove the coating without damaging components?
>>
>
> Try acetone. IIRC it doesn't touch most electronics components, but it
> does dissolve conformal coat.
>
> 'course, if that clear coating doesn't come off with it, it's no help.

Another possibility you could try is an (appropriate) abrasive
tool. If all you need is to open up some solder blobs so you can
unsolder parts, you might be able to use a Dremel tool and a
"grinding wheel" made of that nylon-like material used in kitchen
scrubbing pads. The trick, of course, would be to find a suitable
abrasive that would remove the conformal coating but only polish
the solder and copper.

Come to think of it, you could just try a couple of different
scrubbing pads to see if they do what you want. ... Oh. One old
ex-VHS PC board I found lying around, two different plastic
scrubbing pads, several minutes of effort: no observable
difference.

Can anyone suggest any improvements along these lines? An electric
pencil eraser, perhaps? <grin!>


Frank McKenney
--
It's tough to make predictions, especially about the future.
-- Yogi Berra
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney aatt mindspring ddoott com