When desoldering components from circuit boards, difficulties often arise with components that have many pins. It's clear. If you use a regular soldering iron for such work, then removing a small component from the circuit is not difficult.
It is enough to heat the leads and pull out the part while the solder is soft. If there are many outputs, then it is not possible to heat them all at the same time. In this case, a desoldering braid or other special devices are used.
Removing tin from the board
There are many formulations of solutions for removing tin-lead alloys from the surface of copper.
In this article we will look at several of them and describe the pros and cons of each. I would like to emphasize that testing of the solution recipes in question was carried out only on a chemically deposited coating. I have not checked the suitability of solutions as a remover and dissolver of solder from a printed circuit board.
Vinegar based solution
One of the solutions mentioned on the Internet is a vinegar solution with the addition of ferric chloride and copper sulfate.
Solution composition:
Ferric chloride - 90 g Copper sulfate - 145 g Acetic acid (70%) - 175 g (160 ml) Water - up to a volume of 1 liter Solution temperature 20 - 35 degrees
The solution is prepared as follows: copper sulfate is dissolved in 500 ml of water, then ferric chloride. Acetic acid (70%) is added to this solution and then the volume of the solution is brought to 1 liter with distilled water.
What the solution itself looks like and a test of a chemically tinned strip of PCB.
Test another sample.
The advantage of this etching solution is the speed of removal of the tin-lead coating, the disadvantage is that it is not selective to copper (it etches copper). You need to monitor the process so as not to accidentally etch a lot of copper from the surface of the printed circuit board; the mordants are visible in the photo.
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Hydrochloric acid solution
There is also a recipe for a solution for removing tin-lead coating.
Solution composition:
Hydrochloric acid - 350 g (295 ml) Nickel chloride - 90 g Water - up to a volume of 1 liter Solution temperature 20 - 50 degrees
The stated bleed rate is 10 µm/min.
To prepare this composition, you need to take 700 ml of distilled water, add 295 ml of concentrated hydrochloric acid (density 1.19 g/cm3), then dissolve 90 g of nickel chloride.
But we don’t have concentrated hydrochloric acid, what should we do? We go to the store and buy a similar product containing hydrochloric acid.
Pour 100 ml of the product into the container and try to remove the tin.
Nothing works; the concentration of hydrochloric acid is clearly low for this procedure. Weigh out 7 grams of nickel chloride.
Add hydrochloric acid to the solution and try to etch the tin coating again. Again, nothing worked even with nickel chloride.
We heat the resulting solution (in the microwave) to 70 - 90 degrees and try again. As soon as we lower the test sample into the solution, we immediately notice the release of hydrogen, this indicates that the tin etching process has begun. After 5 minutes, the chemical tin layer was completely removed from the board.
The advantage of this solution is that it does not eat up the copper surface and you can work with this solution at room temperature (this is provided that concentrated hydrochloric acid was used during preparation). The downside is the presence of concentrated hydrochloric acid, which is a precursor and you can’t just buy it. If you use an acid-containing product, the solution will have to be heated, otherwise etching will not occur due to the weak concentration of the acid.
Sulfuric acid solution
Although this solution is positioned as a sulfur solution, the reaction of the components results in nitric acid, in the presence of which the etching of the tin-lead alloy actually occurs.
Solution composition:
Sulfuric acid - 450 g Copper sulfate - 3 g Ammonium nitrate (ammonium nitrate) - 45 g Water - up to a volume of 1 liter Solution temperature 50 - 60 degrees
The stated bleed rate is 10 µm/min.
We dilute copper sulfate and ammonium nitrate (ammonium nitrate) in 100 ml of water, then add battery electrolyte with a density of 1.27 g/cm3 to a volume of 1 liter.
The advantage of this solution is the availability of reagents. The downside is that it is not selective to copper; it poisons it quickly.
I would probably attribute this recipe not to removing tin, but to etching copper. A PCB sample was etched clean in this solution for 10 minutes at room temperature. It will be necessary to test the quality of etching on the boards later.
Solutions based on nitric acid
Solution with iron nitrate (2) Fe(NO3)2
Solution recipe:
Nitric acid - 200 ml Iron(2) nitrate Fe(NO3)2 6H2O - light green crystals - 80 g Water - up to 1 liter volume
— Dissolve lead in nitric acid (caution, violent reaction as it heats up).
— Dissolve iron in sulfuric acid (battery electrolyte).
— Pour lead nitrate into the ferrous sulfate solution until precipitation stops. Lead sulfate will precipitate (it is not needed), in a greenish solution, iron nitrate Fe(NO3)2 will remain.
A few more photos of other experiments.
The advantage of this recipe is the quick etching of the tin coating. Copper eats away, but not quickly. The downside is the production of iron nitrate 2, for which lead is used. I really don’t recommend contacting this metal and when dissolving it in nitric acid, you need to be careful and not smell the reaction vapors. If it is possible to purchase ready-made iron nitrate 2 (light green crystals), then it is better to buy it.
Solution with carbamide (urea)
Solution recipe:
Nitric acid - 300 ml Urea (urea) - 50 g Water - 1 liter
Preparation of the solution. Take 700 ml of water, dissolve 50 grams of urea in it and after it is completely dissolved, add 300 ml of nitric acid.
I threw a test piece of PCB into this solution, after a while the reaction began. Within 5 minutes the chemical tin-lead coating was completely removed from the surface.
The advantage of this recipe is the quick etching of the tin coating. Minus, copper is slightly etched (but can be neglected).
Solution with iron nitrate (3) Fe(NO3)3
Solution recipe:
Nitric acid - 400 ml Iron - 100 g (excess) Urea (urea) - 50 g Water - 800 ml Temperature 20 - 30 degrees
I am obliged to warn that the description of the process and the photo shown are not misleading.
We prepare it this way: dissolve 200 ml of nitrogen in 800 ml of water, throw in iron (bolts, nuts, nails). I advise you to carry out the procedure for dissolving iron in nitrogen outdoors or under ventilation. After the iron dissolves (the reaction stops, after about a day), remove the iron from the solution.
Next, add 200 ml of nitrogen and mix well. Then add 50 grams of urea (urea). Attention, you need to add little by little, since during the reaction carbon dioxide is released and active hissing occurs, due to which the entire contents of the container can spill out.
We dip a test sample of PCB coated with a chemically applied tin-lead coating into the etching solution. literally within a minute there was no trace left of the tin coating.
The advantage of this solution is the high etching speed; it practically does not touch the copper even if the scarf is in the solution for a long time. No cons were noticed.
What is the best recipe for removing tin-lead coating?
Of all the recipes, I liked the most recent solution with iron nitrate 3 and urea. It poisons quickly and practically does not touch copper. But this is just my personal opinion and I don’t want to impose it on anyone.
Try it, experiment, ask questions in the comments.
Clean paths to everyone.
Article written by: Admin Whoby.Ru
How to care for copper products?
There are several recommendations regarding the proper care of copper items. They will help preserve the natural appearance of the metal for as long as possible, so do not neglect them.
There are several such recommendations:
- Copper utensils must be kept clean regularly. After each use, wash thoroughly and dry with a towel. Residual moisture may cause the surface to turn black.
- For cleaning, do not use abrasive substances, as well as products containing chlorine and ammonia. To prevent scratches on the surface, do not use metal spatulas, spoons, or coarse bristled brushes for cleaning.
- Copper jewelry should be wiped with damp wipes as often as possible. This is necessary in order to remove sebum from their surface.
- Products should only be washed by hand, do not use a dishwasher.
If you follow these fairly simple tips, you can significantly extend the life of copper products, as well as maintain their natural shine.
separate the tin plating from the copper casing
is there an easy way?
or not by electrolysis, but at home.
Linux is here despite the fact that only a good dose of strong coffee sometimes helps to overcome its glitches.
maybe if the tin is without bismuth then you can infect it with the plague.
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African or classical?
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What for? A strong solution of copper sulfate and a week of time will help without electrolysis.
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Theoretically, tin dissolves in highly dilute sulfuric acid, but copper does not. You can try diluting battery acid with water 1:10, put a tinned copper plate in it and heat it in a glass pan. If it works, go for it.
A cast of local amateur chemists will explain how to safely dilute and heat acid at home. Or do you have suitable conditions at work?
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Tin is more active than copper, which means it will take away the sulfate ion from the vitriol and go into solution.
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After the acid method, will drinking coffee from such a cezve be harmful?
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I have a lot of vitriol. but wouldn’t it be harmful to drink coffee from it after this?
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Not harmful. Both the original copper sulfate and the result of the reaction, tin sulfate, are slightly toxic, but highly soluble in water. Simply rinsing with plenty of hot water will suffice.
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I read about the plague. Interesting. Maybe I'll try.
I'll go prepare the solution. Then I’ll let you know if I managed to separate the tin.
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After the acid method, will drinking coffee from such a cezve be harmful?
No more harmful than after the vitriol method. You just need to rinse it. Filling and draining water 20 times is considered sufficient. But if vitriol works, it is safer than acid.
Tin is more active than copper, which means it will take away the sulfate ion from the vitriol and go into solution.
The question is not about whether it should be in terms of energy, but about how fast the process will go. Once I tried for a long time and unsuccessfully to dissolve aluminum in hot nitric acid.
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Once I tried for a long time and unsuccessfully to dissolve aluminum in hot nitric acid.
With aluminum everything is more complicated. When exposed to air, it is always covered with a thin film of aluminum oxide, the coarse-crystalline form of which is called corundum or sapphire (the latter is illiterate, but still). It is the second hardest compound after diamond and is chemically very passive. Amalgamated aluminum reacts quite violently even with distilled water.
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The question is not about whether it should be in terms of energy, but about how fast the process will go
But what if you heat it up and the process doesn’t go faster?
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Use freshly boiled solutions (then cool them to 40-50C) to prevent surface oxidation. After etching with sulfuric acid, there should be no tin on the surface, unlike treatment with copper sulfate. The fact is that in a solution of copper sulfate (vitriol) an exchange reaction of Sn - Cu occurs. The released copper can shield the tin from further dissolution. The availability of the tin substrate for etching will be determined by the porosity of the copper deposit. In this case, we can recommend repeated etching in combination with rough surface treatment of the product (fine grinding/polishing).
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separate the tin plating from the copper casing
Go and buy a normal proprietary steel cezve.
Less effective methods for purifying copper
There are other methods for cleaning copper to a shine, but they are either less accessible or ineffective. For example, washing powder is ineffective for cleaning surface contaminants; although it does not harm the top layer of the surface and does not spoil the appearance of the product, it practically does not clean the surface. Also, a bad way to renew this non-ferrous metal is to boil it in Vaseline oil - which is similar in action to a soap solution, but requires less time to carry out the cleansing procedure. Cleaning with ammonia (ammonia) is effective, but it does not allow the copper product to obtain the necessary shine, although it instantly cleans it of oxides and plaque. Although, on the other hand, you will have to do this outside, since this liquid has a pungent, intolerable odor.
detin removal
#1 Nimrod
- Users
- 149 messages
- On the forum: since 2005
- City: Veliky Novgorod
Tell me how and with what you can remove the remnants of tin solder. A friend gave me an interesting buckle, but someone’s playful little hands had been playing with it for a long time. I removed the bulk of the solder with a soldering iron, how to remove the residue?
I read somewhere that orders/medals are removed with some kind of acid. But I can’t remember the specifics. Does anyone have such experience? Tell. The base of the buckle is brass.
Beat in advance
Sincerely yours, Ilya
#2 schrott
- On the forum: since 2004
- City: Sarychan - Tsaritsyn - Stalingrad - Volgograd
PIC can only be removed mechanically from a copper-containing surface.
Removing solder. Excess solder outside the solder seam is removed using a file or scraper.
#3 Nimrod
- On the forum: since 2005
- City: Veliky Novgorod
#4 Fish
- On the forum: since 2004
- Moscow city
#5 pioneer
- On the forum: since 2006
- Moscow city
Try hydrochloric acid.
Heat the braid from a cable, for example, a TV antenna - an old one or another shielded one, with a soldering iron with rosin, and use it as a “napkin” that absorbs the solder. Remains - with a brass brush.
#6 das-ahnenerbe
- On the forum: since 2007
- Samara city
Tell me how and with what you can remove the remnants of tin solder. A friend gave me an interesting buckle, but someone’s playful little hands had been playing with it for a long time. I removed the bulk of the solder with a soldering iron, how to remove the residue?
I read somewhere that orders/medals are removed with some kind of acid. But I can’t remember the specifics. Does anyone have such experience? Tell. The base of the buckle is brass.
Beat in advance
#7 Nimrod
- On the forum: since 2005
- City: Veliky Novgorod
#8 pioneer
- On the forum: since 2006
- Moscow city
pioneer, das-ahnenerbe thanks for the great tips! That's what I'll do.
#9 Fish
- On the forum: since 2004
- Moscow city
#10 pioneer
- On the forum: since 2006
- Moscow city
» Composition for removing tin from brass and copper (g/l): ferric chloride - 75-100 anhydrous copper sulfate. - 120-125 glacial acetic acid 170 -175. Room temperature" (With)
#11 Diga
- On the forum: since 2008
- City: Leningrad region
» Composition for removing tin from brass and copper (g/l): ferric chloride - 75-100 anhydrous copper sulfate. - 120-125 glacial acetic acid 170 -175. Room temperature" (With)
This is after I melted it and shook it off. But it's better to try on something first IMHO.
#12 pioneer
- On the forum: since 2006
- Moscow city
This is after I melted it and shook it off. But it's better to try on something first IMHO. [/quote]I support that this is correct - first remove the solder (tin) as much as possible, with chemical residues carefully (on a corner somewhere). IMHO. [/quote]
Ferric chloride is not weak on copper and its alloys. Ferric chloride is used to poison printed circuit boards (who knows). Copper foil 0.3mm thick or something like that goes away in just an hour. Will supplements help prevent copper and its alloys from being eaten? YOU SHOULD TRY NOT ON THE EDGE BUT ON TIN-PLATED COPPER FOIL. IMHO
How to remove nickel?
Good morning, afternoon, evening
