# How to remove just the solder mask



## banjags (Feb 19, 2008)

Is there away to chemically remove the solder and green/red/yellow solder mask? 

In another post it made mention of using sodium hydroxide. 
If I remember correctly this is what drain cleaners are made of. Can a person just use a bottle drano for this purpose?


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## The Refiner49er (Feb 19, 2008)

Banjags-

The consumer market is almost devoid of any products that are 100% sodium hydroxide, at least in the USA. I had sucess in find the product at plumbing supply companies (wholesale/ industrial type), several industrial chemical suppliers, and scientific supply stores.

Needless to say, the highest cost per unit was the latter, noting the material was high grade. The industrial suppliers had the best price- $70 for 50 lbs. Thats alot of caustic, but the price is right.

I will soon post a proposal to the forum that I believe will benefit most of the members. 

The supplies that are used for refining that can be shipped without complications (hazardous materials) could be purchased in bulk form, repackaged in appropriate sizes, and distributed to members of the forum. The individual(s) that acquire, pack and ship these materials could make a reasonable profit for their efforts and still deliver the consumables at a price well below retail.

The primary intention is not of profit, but of reduced costs by collective purchasing. 

I welcome any opinions or contributions regarding this concept.

Thank you!


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## Chuck_Revised (Feb 19, 2008)

And what supplies might those be? Aren't most of the chemicals hazardous materials?

I'm centrally located in Kansas City, Missouri (for the US members). I might consider such an arrangement. I would be in it for a profit, as substantial time could be involved. But it might work out for all. We'd have to keep repackaging costs down and limit final shipping vendors.

So provide details of possible items and quantities. Let the forum provide input and info.


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## The Refiner49er (Feb 19, 2008)

Chuck-

I am just beginning to look into this, I am sure there are restrictions on the more hazardous chemicals. I have seen several sellers on Ebay marketing 1 lb packages of various dry materials.

I can purchase sodium nitrate at a farm supply wholesaler for $24 per 50 lb bag. Today I knocked the price down on sodium hydroxide to $50 for 50 lbs. As Irons has pointed out, NaOH decomposes over time, so it is impractical to buy/store it in bulk.

I have yet to investigate the shipping regulations for the chemicals refiners are using, but if they can sell it on Ebay and send USPS Flat Rate, then we should be able to do the same, at least for certain dry materials.

I am going to start a new thread with this info, and will add more as I acquire it.

Thanks!


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## The Refiner49er (Feb 19, 2008)

Chuck-

Look under chemicals for my most recent post on collective purchasing.

I will update as the information becomes available.

Thanks!


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## banjags (Feb 20, 2008)

I could be the canadian distributer being centrally located in Winnipeg,MB. 

But no one answered my original question.


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## banjags (Feb 21, 2008)

I have a small piece of a gold plated circuit board swimming in drano all of last night. Nothing seems to have happened to the solder mask. There is a bunch of white "fluff" stuck to some of the metal slivers sticking out of the solder points. (from caps that i busted off and so on). It is a section of an old ensoniq sound card. I had scratched of a large section of the mask before placing it in the drano. Thought it might help it. 

Any ideas why this does not seem to work?


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## Gotrek (Feb 21, 2008)

They have solder mask thinner at active electronics. They might have a remover as well.

How about media blasting the boards? Cheap, renewable(if you use a cabinet) Problem is finding the right media to remove only the mask.


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## Chuck_Revised (Feb 21, 2008)

Banjag, sorry to wonder off topic.

I'm can't seem to just move a link so do this:

Go to the "Forum Improvement/Ideas" section of this forum.
Go to the topic "Do Gold Recovery.info is OK?", page 3, scroll down and you'll find what you're looking for.

:arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?p=1214#1214

I located it by a search of the forum: solder AND mask

May your yields always be high and your methods efficient!


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## banjags (Feb 21, 2008)

hmm, weird place for that post. Thank you...
I was under the impression that the mask would dissolve.
Maybe all it needs is a scrubbing. Why is it important to make sure there is no solder on the boards before putting them in sodium hydroxide?

He also mentions mixing up sodium hydroxide with water. would this be a powder mixed with water?
Or should I be adding water to my liquid drano?

Just looked up the msds of liquid drano. The Sodium Hydroxide level is very low. 1-5% by weight.

Should be using the crystals. 30-60% by weight. They also contain sodium nitrate 15-40%... would this have uses elsewhere?


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## Chuck_Revised (Feb 21, 2008)

Sorry, I can't answer your questions. I don't actively refine yet and may not due to space and safety issues. You might check the info under chemicals for sodium hydroxide information. You could also PM the authors of the posts.


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## Shaul (Feb 21, 2008)

The original post spoke of using Sodium Hydroxide powder or crystals with distilled water and added salt.

Shaul


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## banjags (Feb 22, 2008)

OK so yesterday I bought some drano professional strength kitchen crystals. Poured enought water in to just cover the board and about 2 heaping table spoons of crystals. Stirred it up and quickly took it outside.(very stinky and generated a ton of heat. almost burnt my fingers thru the small tub I was using.) 
I left it overnight (-20 celcius outside)and the board was stripped perfectly clean. At first it looked like it was going to need a second bath until i rinsed it with hot water. This stuff worked very well it was under $5 for 2 #s.
Success. I am going to try a much large batch tonite.


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## Gotrek (Feb 22, 2008)

Do you think it would work for spot treatment? I have a few boards I want to repair and scraping the mask sometimes damages other parts.


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## banjags (Feb 22, 2008)

it might if you applied it with a drop it would need to be very concentrated and the board would need to remain perfectly still but it could work.


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## Gotrek (Feb 22, 2008)

banjags said:


> it might if you applied it with a drop it would need to be very concentrated and the board would need to remain perfectly still but it could work.



Guess I'm going to have to try it ehh  Thanks for the research.


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## banjags (Feb 22, 2008)

i dont know if this would affect the functionality of it or not, but all the solder and metal points on the board that I did turned black and maybe some of the solder was dissolved... not sure. Didnt look that carefully was too in awe looking at all the gold plating on the board... shiny!!! LOL


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## Gotrek (Feb 22, 2008)

banjags said:


> i dont know if this would affect the functionality of it or not, but all the solder and metal points on the board that I did turned black and maybe some of the solder was dissolved... not sure. Didnt look that carefully was too in awe looking at all the gold plating on the board... shiny!!! LOL




Ha ha right forgot about the gold  Well I'll test it on scrap. no big deal either way scrapping works.


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## banjags (Feb 23, 2008)

does anyone know if this solution will dissolve gold at all? Now that i have dissoved the solder mask of a number of gold plated boards I want to make sure that I am not throwin any values away.


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## donald236 (Mar 18, 2008)

hi all 
i found a way to remove that solder mask and it might be cost effective.
here's a web site that backs it up.

http://www.circuitmedic.com/features/514.shtml

its talking about a chemical that removes the solder mask fast . the chemical in question is a methylene chloride based stripper . but it will deteriorate base metals if it's left on to long . as for me it wont be on there that long if it's that fast . i thought every body should know .i hope this helps every body .

donald


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