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Need help with electroless tin plating of PCB


Hi, I am looking for the method of electroless tin plating of printed circuit boards. In my country I cannot simply go to a shop and buy some plating crystals, and therefore need to actually make up the stuff to do this. Electronics is my hobby, and so any help will be GREATLY appreciated.

Thanks very much

Gordon [last name deleted for privacy by Editor]

Hello, Gordon,
The Metal Finishing Guidebook lists three formulations for immersion deposits of tin onto copper, only one of which is cyanide-free:
Stannous chloride 3.8 g/L,
Thiourea 49.5 g/L,
Sulfuric acid 12 ml/L,
temperature 80-120 degrees Fahrenheit.

However, immersion deposits of tin may not be a fully acceptable substitute for electrolytic tin-lead.

Ted Mooney   Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey



A little while ago you assisted me by letting me know the mixture for electroless tin plating of copper on PCB. It was stannous chloride 3.8 g/l thiourea 49.5 g/l and sulphuric acid 12 ml/l. But I do not know what strength the sulphuric acid is supposed to be. Please could you assist me with this as I have now found a place to get the thiourea and would like to try the plating as soon as possible.

Thank you for you help.

Gordon [last name deleted for privacy by Editor]
- computers


The source doesn't say, Gordon. I must assume it's 66 degree baume (96 percent) sulphuric acid. There are several other formulas for generic electroless tin solutions; you might want to consult some of the standard reference books on this. Good luck.

Ted Mooney,   Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

sidebar2 -

Anyone contemplating the use of the above recipe should first read the MSDS on thiourea:

Cor Grooff
- Netherlands


I plated ceramics without conductive material. I used immersion Tin 2% Sn Conc. 5% HCl .I preplate before electroless Ni.and Immersion gold to protect nickel from oxidation.I plated ceramics for 15 years but I look for this information myself . I never work with electroless Sn.Let me know if you find one to develop this chemical. It will save a lot of cost reduction.

Good Luck,

Duang Bouphasavanh
- Myrtle Beach,South Carolina


We manufacture single and double-sided Printed circuit boards and they are what we call "Roller Tinned" or "Roller Plated" as some people would express the term.

I need to "LEAD/TIN" plate the PCB'S and need a formula. Do explain how this may be achieved by the "Electroless" system and [alternately by] using a rectifier .

Thank you

Christopher Halgryn
- New Zealand

Duang Bouphasavanh,

you mentioned that you used a process to tin plate a nonconductive ceramic? Am I understanding you correctly that you used the electroless tin process to activate a nonconductive ceramic object for electroplating? If this is so,what exactly was the recipe for your solution? I am very interested in this for circuit boards. I've considered Tollens reagent,but silver is expensive and not the best solution.

Michael Michalski
- Sacramento, California

Printed Circuits Handbook


I have used Stannous Chloride for years to prepare Electroless Tin Plating for PCB. You can try the following recipe:

Stannous Chloride 5 grams/liter
Sulphuric Acid (66 Be) 10 ml/liter
Thiourea 50 grams/liter
Use only distilled water or demineralized water.

Careful must be taken for Sulphuric acid over water.

Juan Oyarce
PCB-CNC - Santiago, Chile

The best way to electro plate non metals is to use palladium. It is very expensive but it will last forever as long as you use it regularly.
By dipping or submerging the non-metals in the palladium for 5 min, remove and drip dry. Plating electroless or electroplating as normal.

Johan Gagiano
Electronic Designing - Worcester, South Africa

In the recipe you mention Stannous Chloride 3.8 g/L.
Is this SnCl2 [anhydrous] or SnCl2.2H2O [dihydrate] or will both do equally well?

Thanks for your reply,

Hans Schaaper
hobbyist - Alkmaar, NH, The Netherlands
July 10, 2008

We are making PCB The tin plating we need should be Electroless. But how the mentioned processes are possible for the exploitation on Manufacturing Level? Which parameters are critical for maintaining?
I had tried but we got Black slurry & minor tin plating, How to reduce this problem? The Sn was released in Black Granules form I suppose. Then the process will be expensive. How to control Thickness, whatever it may be.

Chetan Choudhari
Owner, associate unit - Nasik, Maharashtra , INDIA
October 12, 2008

Can you give more information on what you try to accomplish? If I can help you out and I love to solve the problems people had. Thanks,

Duang Bouphasavanh (returning)
- Myrtle Beach, South Carolina
March 8, 2009

I am also Looking for PTH PCB activator material, I have found this formula if anyone has a simple and cheap formula Please let me know.

The activation
solution contained

PdCl2 0.4 g/l,
SnCl2 4.5 g/l
HCl (37%) 500 ml/l

- Faisalabad,Punjab,Pakistan
July 21, 2009

The process I operated one for etching and follow two rinses tanks and Tin sensitizer bath with two rinses tanks and palladium bath is activator for the electroless nickel to plate.Before I plated nickel after activates and I changed the rack that will help from contamination on my EN bath.If you want to cut cost of chemicals,I will spend two days to study the process how it works or it will take at least a month to prove make sure it passed all test.You have a tin chloride bath : 2%Sn + 5%HCL + 93%DI H2O
Palladium bath : 8%Pd + 92%DI H2O.It depends who you buy the chemical from.I hope it will help you out.Good Luck,

Duang Bouphasavanh (returning)
- Myrtle Beach,South Carolina
April 24, 2011

hello dear
I've tried to do electroless plating of tin on copper PCB and has worked and I've used the formula Stannous chloride 3.8 g/l, Thiourea 49.5 g/l, Sulfuric acid 12 ml/L.
But the surface wasn't bright, so how can I make the surface bright.


Hanibal Najjar
university teacher - Gaza

January 11, 2012

You can get a bright finish with "Bar Keeper's Friend" - it probably goes by another name in Gaza... It is a cleaner used by restaurants for polishing brass, copper and such. The active ingredient is 5% oxalic acid - which shouldn't be any problem - mixed with a mild abrasive and a bit of detergent.

Nicholas O. Lindan
- Cleveland, Ohio, USA

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