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Hacking a PCB: How to Remove Coating

Started by Jim Thompson July 1, 2012
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
-- 
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.
"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote 
in message news:rgk1v75nbc0cj5b75mppfom36bn9jjl5et@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
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
On Sun, 1 Jul 2012 20:07:05 -0400, "Martin Riddle"
<martin_rid@verizon.net> wrote:

> >"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote >in message news:rgk1v75nbc0cj5b75mppfom36bn9jjl5et@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 -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote 
in message news:d502v7trgnu8a50sac5in41p503ednu9gg@4ax.com...
> On Sun, 1 Jul 2012 20:07:05 -0400, "Martin Riddle" > <martin_rid@verizon.net> wrote: > >> >>"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> >>wrote >>in message news:rgk1v75nbc0cj5b75mppfom36bn9jjl5et@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
On Sun, 01 Jul 2012 15:50:29 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@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
On Mon, 02 Jul 2012 11:50:19 -0500, legg <legg@nospam.magma.ca> wrote:

>On Sun, 01 Jul 2012 15:50:29 -0700, Jim Thompson ><To-Email-Use-The-Envelope-Icon@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
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 -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Mon, 02 Jul 2012 11:50:19 -0500, legg <legg@nospam.magma.ca> wrote:

>On Sun, 01 Jul 2012 15:50:29 -0700, Jim Thompson ><To-Email-Use-The-Envelope-Icon@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 -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
On Mon, 02 Jul 2012 10:12:29 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@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.
On Sun, 1 Jul 2012 22:08:43 -0400, "Martin Riddle"
<martin_rid@verizon.net> wrote:

> >"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote >in message news:d502v7trgnu8a50sac5in41p503ednu9gg@4ax.com... >> On Sun, 1 Jul 2012 20:07:05 -0400, "Martin Riddle" >> <martin_rid@verizon.net> wrote: >> >>> >>>"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> >>>wrote >>>in message news:rgk1v75nbc0cj5b75mppfom36bn9jjl5et@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 > >
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? ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.