Solder Masks and Pea Soup?
- Thread starter Astraveller
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You have the good stuff.
I have found it as Crystal Draino in metal Canisters at Lowes in the plumbing section and as Rooto crystals of Household drain opener at the
True Value hardware store in my area. The Rooto package says 100% lye on the front of the plastic bottle. It is a 16 oz package (454 grams)
I also buy the Rooto h2so4 gal size drain cleaner at the same True Value Hardware store.
True Value hardware store in my area. The Rooto package says 100% lye on the front of the plastic bottle. It is a 16 oz package (454 grams)
I also buy the Rooto h2so4 gal size drain cleaner at the same True Value Hardware store.
oldtimmer
Well-known member
Finally able to start another batch of solder masks boards today. After a week of prep work and cutting down boards, they went into the soup mix today.
I started with a cup of rock salt (don't know, but it was recommended in one post). I took about 1 gallon of hot water out of the tub. To this I added about 2.5 gallons of very hot water which I had put on the stove and allowed it to just start to bubble very lightly. Then took the hot water bucket outside to the side yard. I put half of the boards in. I then added a full can of Draino plus a left over half can to the water followed by the remaining boards. It took about 10 minutes for the bucket to get really hot and the mixture to boil. I took the precaution of putting the bucket inside of another one, just incase.
I checked the mix after 3.5 hours. Still a small boiling action and a lot of green solder mask floating on the top of the foam. I then very carefully removed three of the five different types of boards to check on how the removal was doing. After rinseing off these boards wit clean water, If ond that the solder mask would come off with a gentle rubbing action with my rubber gloves. I could not get to the other two types of solder mask boards as they were too far down in the bucket.
So my conclusion is that the water must be fairly hot to start and that the added heat at the start has made the difference. These are the same type of boards that I had tried before with little success. The last time the water was not as hot to start and I did not see the boiling action of the Draino that I saw this time. Did the salt help or not, I do not know, but I have acheived the results that are needed.
I will post final results and pictures later in the week.
I started with a cup of rock salt (don't know, but it was recommended in one post). I took about 1 gallon of hot water out of the tub. To this I added about 2.5 gallons of very hot water which I had put on the stove and allowed it to just start to bubble very lightly. Then took the hot water bucket outside to the side yard. I put half of the boards in. I then added a full can of Draino plus a left over half can to the water followed by the remaining boards. It took about 10 minutes for the bucket to get really hot and the mixture to boil. I took the precaution of putting the bucket inside of another one, just incase.
I checked the mix after 3.5 hours. Still a small boiling action and a lot of green solder mask floating on the top of the foam. I then very carefully removed three of the five different types of boards to check on how the removal was doing. After rinseing off these boards wit clean water, If ond that the solder mask would come off with a gentle rubbing action with my rubber gloves. I could not get to the other two types of solder mask boards as they were too far down in the bucket.
So my conclusion is that the water must be fairly hot to start and that the added heat at the start has made the difference. These are the same type of boards that I had tried before with little success. The last time the water was not as hot to start and I did not see the boiling action of the Draino that I saw this time. Did the salt help or not, I do not know, but I have acheived the results that are needed.
I will post final results and pictures later in the week.
nicknitro
Well-known member
Ya know,
I never really considered that the salt would raise the boiling temp of the aqueous solution. What is the boiling point of Lye mixed with water again ? Would salt help raise the temperature at all? 212 to 240 to 300 could make leaps and bounds of difference to stripping capabilities.
I still question the relevance of the salt chemically. The Lye already performs it's duty with heat.
Curious,
Nick
I never really considered that the salt would raise the boiling temp of the aqueous solution. What is the boiling point of Lye mixed with water again ? Would salt help raise the temperature at all? 212 to 240 to 300 could make leaps and bounds of difference to stripping capabilities.
I still question the relevance of the salt chemically. The Lye already performs it's duty with heat.
Curious,
Nick
A
Anonymous
Guest
Hey guys,does anyone know the effects of the lye solution on ptfe?I have a some 55 gallon plastic drums and a couple hundred pounds of gold traced boards but I really dont want to end up with a caustic soda "lake" in my backyard.Dont get me wrong,I could use a new pool,but my skin just burns a little too easy.If I dont hear a reply by tonight I'll just cut off a small piece and let it soak for a week or two and test the consistency of it.
Johnny
Johnny
Hi
I work along side astraveller with the gold refining Tonyd
None of our caustic was heated all we done was let a small amount of plated cards sit in the caustic for a number of days and then had a look.
What we found is what astraveller posted early on in this thread.
Patience is all it takes.
How can it be waste if someone wants it
I work along side astraveller with the gold refining Tonyd
None of our caustic was heated all we done was let a small amount of plated cards sit in the caustic for a number of days and then had a look.
What we found is what astraveller posted early on in this thread.
Patience is all it takes.
How can it be waste if someone wants it
Astraveller
Active member
Hi guys,
I thought some might be interested in what we discovered today. We left some gold plated boards in caustic to dissolve the solder mask and today I thought it would be a good idea to clean of the ones that were ready.
I rinsed them off and washed them in running water for a minute or so and then used a plastic washing up brush to clean of the remaining green solder mask. In the process I noticed that some of the boards were showing ‘silver’ printed circuit board as well as the gold. I sanded down through ‘silver’ to the copper underneath and then through to the green board.
It very much looks like the caustic has either 1) eaten into the gold or 2) eaten into the layers underneath and allowed the gold to lift off.
I examined both the caustic dish and the rinse dish, which I used to clean the board during scrubbing and both contained tiny flakes of gold in the sludge. I tried the stannous test on a drop of the caustic – all this did was to produce a little plume of ‘smoke’ and ‘tested’ negative.
This throws up a number of questions – off the top of my head:-
1. Can caustic soda dissolve gold? (Doubtful – someone would have discovered that by now and it would be common knowledge)
2. Is the caustic allowing the gold to lift off?
3. What is the ‘silver’ layer in between the gold plate and the copper layer?
4. Is the gold so thin that caustic and modest abrasion just wears it away like cheap thinly plated jewelry?
5. If it’s that thin, is it worth bothering with?
6. How do you recover and process gold flakes from caustic sludge?
7. I read somewhere that any adversity has within it the seeds of an equal or greater benefit – does anyone see one here?
It does, however, seem that if caustic soda is to be used to prepare these kinds of boards (with or without heat) for the AP process, the caustic process needs to be monitored carefully.
I have included a couple of pics of the boards and the bottom of the caustic dish which does have gold flakes in but I am not sure how clearly they can be seen but they are there.
I would welcome any thoughts or comments.
Linton.
I thought some might be interested in what we discovered today. We left some gold plated boards in caustic to dissolve the solder mask and today I thought it would be a good idea to clean of the ones that were ready.
I rinsed them off and washed them in running water for a minute or so and then used a plastic washing up brush to clean of the remaining green solder mask. In the process I noticed that some of the boards were showing ‘silver’ printed circuit board as well as the gold. I sanded down through ‘silver’ to the copper underneath and then through to the green board.
It very much looks like the caustic has either 1) eaten into the gold or 2) eaten into the layers underneath and allowed the gold to lift off.
I examined both the caustic dish and the rinse dish, which I used to clean the board during scrubbing and both contained tiny flakes of gold in the sludge. I tried the stannous test on a drop of the caustic – all this did was to produce a little plume of ‘smoke’ and ‘tested’ negative.
This throws up a number of questions – off the top of my head:-
1. Can caustic soda dissolve gold? (Doubtful – someone would have discovered that by now and it would be common knowledge)
2. Is the caustic allowing the gold to lift off?
3. What is the ‘silver’ layer in between the gold plate and the copper layer?
4. Is the gold so thin that caustic and modest abrasion just wears it away like cheap thinly plated jewelry?
5. If it’s that thin, is it worth bothering with?
6. How do you recover and process gold flakes from caustic sludge?
7. I read somewhere that any adversity has within it the seeds of an equal or greater benefit – does anyone see one here?
It does, however, seem that if caustic soda is to be used to prepare these kinds of boards (with or without heat) for the AP process, the caustic process needs to be monitored carefully.
I have included a couple of pics of the boards and the bottom of the caustic dish which does have gold flakes in but I am not sure how clearly they can be seen but they are there.
I would welcome any thoughts or comments.
Linton.
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1- NO. Nor will it eat Ni or Cu.
2- I don't see how. It could eat the adhesive that holds the copper traces onto the board material itself. In that case, though, the Au, Ni, and Cu would come off together.
If the gold were plated on solder (Sn/Pb) plate, the NaOH could attack it and flake off the gold. I have never seen gold plated on solder plate, but that doesn't mean it's impossible.
3- It there was gold on the traces to start with - of which I have grave doubts - the silver colored metal is usually nickel. If there was no gold, it could be nickel or solder plate.
4- Possibly, but I doubt that a bristle brush would do it.
5- Probably not, whether it's thin or thick.
6- Dilute it considerably (less than about 5% NaOH) and filter it. If the NaOH is too strong or hot, it will eat the paper.
Astraveller
Active member
Thanks GSP, that’s what I thought – for the most part!
But.
7. I read somewhere that any adversity has within it the seeds of an equal or greater benefit – does anyone see one here?
I am a newbie.
Linton.
But.
7. I read somewhere that any adversity has within it the seeds of an equal or greater benefit – does anyone see one here?
I am a newbie.
Linton.
Astraveller
Active member
GSP, you revised your post and expanded on it, I thank you!
Linton.
Linton.
I have seen similar results on some boards that was laying in NaCl a week or more. Some of the tin or lead was dissolved an replated on top of certain traces. I always suspected it to do that because of elecronegativity of led or tin forming an electrolytic cell. Solder goes into solution while tin is plated out on the gold plated traces.
Try to put the board in HCl, it should remove the tin on top and show you the golden surface again if I'm right.
The plating is really thin and is hard to see when sanding through the copper traces. Not only that it is thin, if you have tin on top it will smear and cover any traceof gold in the sanding area.
If you have an exposed metallic area, just add a drop of nitric acid on top of it and soon you will see the plating floating around inside the drop. Then you will know if it is thin or thick plating.
Try to put the board in HCl, it should remove the tin on top and show you the golden surface again if I'm right.
The plating is really thin and is hard to see when sanding through the copper traces. Not only that it is thin, if you have tin on top it will smear and cover any traceof gold in the sanding area.
If you have an exposed metallic area, just add a drop of nitric acid on top of it and soon you will see the plating floating around inside the drop. Then you will know if it is thin or thick plating.
g_axelsson said:
That doesn't make much sense to me. Tin or lead won't cement onto gold, ever. Something else must be going on. If there is gold and if the gold is very thin, it will be very porous, exposing the nickel. Maybe the Pb or Sn is cementing onto the nickel through the pores.
You will also know if the gold is non-existent.
goldsilverpro said:
And still I have seen it...
I was not thinking about cementing out tin or lead as silver does on copper. I was thinking in the way of electrolysis. Tin have higher electronegativity than copper, if a board with gold plated copper traces is placed in a solution with tin in solution where would it go? Would copper go into solution while tin is plated on the exposed metal surface? Why would it not attach to the gold surface?
The interesting part is that I had a number of boards from a HP computer. They only had solder mask on one side but it was fully gold plated on both sides. The gold was thick enough to be picked up in cm-long pieces once it was free of the board.
One trace could be unaffected gold and the next fully plated with a silvery metal after a week in lye. As the board was broken in parts to fit into the bucket some traces were in contact with solder on the board and some were not. I don't remember which category of trace that got the "solder plate".
I think I still have that board unprocessed. I'll take a picture when I find it but it could take a while. I'm helping a friend to clean out a 60 square meters storage space full of old computers (Norsk Data minis) and terminals.
If I haven't posted a picture in june, just remind me.
In the electromotive series tin is higher in series than copper,
so if both are in an acid of say copper ions disolved, the tin would dissolve in the acid and precipitate the copper as the tin loaded the acid.
If two metals are in an acid say copper and gold the gold would try to plate to the copper. the metal lower or less reactive would try to plate to the more reactive metal, (not the other way around).
And the more reactive metal will displace the less reative metal from a solution, try doing a little study on this it is such a important part of what we do, understanding it can help you solve problems.
so if both are in an acid of say copper ions disolved, the tin would dissolve in the acid and precipitate the copper as the tin loaded the acid.
If two metals are in an acid say copper and gold the gold would try to plate to the copper. the metal lower or less reactive would try to plate to the more reactive metal, (not the other way around).
And the more reactive metal will displace the less reative metal from a solution, try doing a little study on this it is such a important part of what we do, understanding it can help you solve problems.
wop1969
Well-known member
To add to this post, I found a dark colord sound blaster live card and dropped it in a bucket with about 8 cups of water and 4 healthy tablespoons of crystal draino (LYE) I did heat the water with the coffe maker first, their was allot of boiling noise and the bucket got very hot (had it in a pan) and then the reaction stopped.
2 days later I pulled it out and sprayed it with the water bottle on streem and everything rinsed off with no effort.
I will strip a piece of trace and run it and test it and post my finding.
The card was a sound blaster live, if anyone knows if they covered in gold or not, please respond, I will post my findings otherwise.
One more thing ,the traces on the finger are the same color as the rest of the board, and I know the fingers are gold but a test is still in order.
Here is the finished results.
2 days later I pulled it out and sprayed it with the water bottle on streem and everything rinsed off with no effort.
I will strip a piece of trace and run it and test it and post my finding.
The card was a sound blaster live, if anyone knows if they covered in gold or not, please respond, I will post my findings otherwise.
One more thing ,the traces on the finger are the same color as the rest of the board, and I know the fingers are gold but a test is still in order.
Here is the finished results.
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A very good admonition, Texan. Thanks for bringing up the subject.texan said:
Years ago I had the misfortune of having a drop of nitric acid splash in my right eye. I was alone, and couldn't see from that eye (the surface of the eye turned yellow and shed almost immediately). I drove myself to an ophthalmologist, who informed me how lucky I was. I didn't think so, but he went on to inform me that had the drop been lye (sodium hydroxide) I most likely would have lost the vision in the eye. I was told the eye would return to normal, which it did. A valuable lesson in wearing safety gear, one that I didn't really need to learn, for I was already aware of the stupidity of working without eye protection.
Wear the safety gear, folks.
Harold
