# How Do I Remove Top Sealer From PC Boards?



## Anonymous (May 9, 2012)

Hello members,

I think I saw a video on YouTube a few weeks ago or maybe a month now, and it was about how to remove the coating on top of pc boards. 

The video showed a board that was gold plated, but it was protected by the coating/sealant that protects the board from moisture and such. In the video the man put the pc board (I think a cell phone board) in a pot of water and (or) something else and let it boil or cook for awhile. After cooking in the pot on the stove, he showed how to just easily wipe the protecting shield away from the board.

The problem I have is that I've looked and looked very hard, but I can't seem to find the video. I thought I saved it, or liked it in my YouTube account(s), but I still can't find it.

Does anyone know how that process is done...? because I do have a motherboard and the bottom of it appears to be gold plating and I want to be able to strip the coating off of it after I remove the components.

I'm going to keep looking in the meantime, especially in my history from my browser if I can't relocate the video. If I find the video I'll post the link here for others that may want to strip the coatings off of their boards.

Kevin


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## martyn111 (May 9, 2012)

There is another thread running at the moment discussing this subject


http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=13432


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## Geo (May 9, 2012)

its a solution of sodium hydroxide (caustic soda or lye) and water. the video to see this process is lazersteves website www.goldrecovery.us

login using the username : gold

and password : goldm1ner*

solder mask removal.


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## Anonymous (May 9, 2012)

Thanks for the reply *martyn111*!



Geo said:


> its a solution of sodium hydroxide (caustic soda or lye) and water. the video to see this process is lazersteves website http://www.goldrecovery.us
> 
> login using the username : gold
> 
> ...


Thanks Geo... that's where I saw the video. I thought it was on Youtube.... no wonder I couldn't find it there.

On another note of the same subject, let me suggest that if you point a link/video for someone to see, point to the exact link/page they need to go to. Once I logged into Steve's site, I even did a search for the video, but there are no links in the search results to that video. How I got to the video was coming back here and went to the link that *martyn111* posted and found the link to the actual video, which is at http://www.goldrecovery.us/goldrecovery/videos/ShowVideo.aspx?id=soldermask&yt=0.

Anyway, thank you for the reply because that's the exact video I saw that I do remember about removing the solder mask. And now I also know it's real name is solder mask and what is used to remove it.

Thanks to all of you.... I'm so glad I'm learning more and more each and every day here on this forum.

Oh, and by the way, I've purchased all of Lazersteve's videos a few weeks ago. They're great and I do recommend them to everyone that is into precious metals and the process of recovery and refining.

Kevin


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## Beirdo (Jun 4, 2012)

Would this work as well with potassium hydroxide? I likely will have a bunch of it (from wood ash amongst other sources) and it would be good to reuse rather than buy, if possible.


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## maynman1751 (Jun 4, 2012)

I use KOH and it works just fine. Be careful, this stuff is still as dangerous as hot acid. Wear plenty of protection. Even the smallest droplet burns like Hell!


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## Beirdo (Jun 4, 2012)

Yes, both NaOH and KOH are not chemicals to be trifled with. Nasty burns can and will occur if you aren't extremely careful. Luckily from wood ashes, the concentration is fairly low (until you evaporate it down), but still, your warning is well heeded. Eye protection and skin protection are a must, really.

I figured KOH would likely work as it sounds like the unknown process at work was more likely the hydroxide ion at work rather than the sodium ion. And since you've tried it successfully, great! Thanks.


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## nickvc (Jun 5, 2012)

All strong alkalis need treating with utmost respect and care they will do more damage to all human tissue faster and more efficiently than virtually all acids, remember cyanide is a strong alkali!

Always wear eye protection as a minimum, one splash of most acids we use in the eye will cause pain and permanent damage if not treated quickly by rinsing with water and a visit to the hospital or doctors, one splash of lye will lose you your eye permanently!


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## Beirdo (Jun 6, 2012)

nickvc said:


> remember cyanide is a strong alkali!



Citation please?

From all I've read, the cyanide ion itself is not alkaline nor acidic, but hydrogen cyanide is acidic. I'm not sure where this information is from.

Anyways, cyanide is a whole different ball of wax anyways as it is toxic in and of itself. Potassium hydroxide and sodium hydroxide are not in and of themselves toxic (although I wouldn't be drinking their solutions, especially not concentrated!). The danger in strong alkaline solutions is in the damage it does breaking down organic substances, including your skin and any other part of your body. However, lye (sodium hydroxide) and caustic potash (potassium hydroxide) are used to make soap as well (hard and soft soaps respectively), and when treated with the utmost care and with proper protective equipment, are perfectly safe. I used them in their pure form in high school for goodness sakes.

Of course, read the MSDS sheets to be sure before using any chemical.

Back on topic... when we digest the solder mask with caustics, what is the proper way to dispose of the remains of the solder mask? Is it OK to introduce that into a city sewer system, or is there some preparation needed or special disposal requirements?


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## Harold_V (Jun 7, 2012)

Beirdo said:


> nickvc said:
> 
> 
> > remember cyanide is a strong alkali!
> ...


That, in and of itself, should be all the citation you need. The point here is that cyanide, as it applies to gold, is generally in a strong alkali condition, to assure that no hydrocyanic acid is evolved. To my knowledge, and with the experiences I had, it should be kept at a pH of no lower than 9½. That, then, warrants the admonition to remember that cyanide is strong alkali, whether the ion itself is, or is not. 

Remember, we have readers, here, from all walks of life. They may not understand the hazards of many of these substances. We all try to keep readers well advised, if for no other reason, their personal safety. 

I stand to be corrected, and welcome anything that will help me have a better understanding.

Harold


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## Beirdo (Jun 9, 2012)

I think for clarity (this forum *does* pride itself on clear accurate information), the nature of "cyanide" (more particularly sodium cyanide) should be examined. I am here with hat in hand to say... hmmm. Yes, sodium cyanide *can* in fact be considered a fairly strong base. It is the sodium salt of a weak acid (HCN) and a strong base (NaOH). When you dissolve it alone in water, it will form an alkaline solution and a very toxic gas.

NaCN(s) + H20(l) -> Na+(aq) + OH-(aq) + HCN(g)

Well, I'll be... 

It was still completely from left field in this particular topic (removing solder mask from circuit boards with alkaline solutions) as nobody was silly enough to consider it as an alternative. I was in fact only asking about KOH as a substitute for NaOH in the process. You'd be a suicidal fool to choose to use NaCN instead.

Anyways... any ideas on the disposal of the results of digesting the solder mask with hydroxides?


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## butcher (Jun 9, 2012)

Anyways... any ideas on the disposal of the results of digesting the solder mask with hydroxides?

I use the caustic waste solution’s to neutralize acidic waste solutions, after dropping the metals below iron in the reactivity series.


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## Beirdo (Jun 9, 2012)

Oooh, that's a good idea. Use the one waste to neutralize another waste. Nice! Certainly better than wasting perfectly good fresh vinegar or baking soda to do the various neutralizations.


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