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Electroplating of iron onto copper soldering iron tips


Q. How do we do iron coating on copper bits used in soldering irons?

Preet Sdeleted
- New Delhi, India



A. Dear Preet,

Please continue on down this page that you've started, and you'll see good technical answers develop. For a less technical answer, you may be able to obtain a license from a soldering iron manufacturer to use the technology they have developed, or find a supplier of a proprietary iron plating process who will assist you with the application of their process chemistry.

While waiting for the thread to develop, you might also do a computerized search of the published literature; there have been a few articles on this subject in the journals over the years. Perhaps Metal Finishing Information Service at www.surfacequery.com can assist you with that if you don't currently have access to such databases.

Or start by telling us what you know and don't know. That always generates much better response than short, open ended requests for information because people generally won't spend more time here on an inquirer's behalf than the inquirer spent here himself. Good luck.

Regards,
pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



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Q. I am a hobbyist mainly in the electronic field. I understand that lead-free soldering is the new trend. When I started soldering PCBs with lead-free solder I found the solder iron tip decay rate is very high. Then I referred to the internet and I saw that the high Tin (Sn) content in the lead-free solder is eating the copper tip. Further I understand that lead-free soldering irons have special tips which have been iron plated on the copper bit to prevent this fast decay. My soldering iron has no such bits available in the market and I thought to make and try one tip myself. Therefore, can you describe how to electroplate Iron onto a copper soldering bit (a copper rod)
Thank you.

Gamini Cdeleted
Hobbyist - Negombo, Sri Lanka

Quality Hand Soldering & Circuit Board Repair


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A. Iron plating is more difficult for hobbyists than some other types of plating, Gamini, because iron has multiple oxidation states. Without proper attention, or with exposure to air, the iron will oxidize to the higher oxidation level from which state it is not longer soluble and can't be plated -- so avoid air agitation.

I think a hobbyist with no plating experience will have a significantly harder time successfully doing iron plating than starting with something else like nickel or zinc, so if you are determined to learn to electroplate, I'd suggest practice with nickel plating first.

Some plating references don't even cover iron plating because it's rather uncommon, but 6 baths are discussed in Lowenheim's "Electroplating" .

The simplest is probably the
240 g/l FeSO4.6H2O bath operated at
pH of 2.8-3.5 and
temperature of 32-65 °C,
current density 400-1000 A/sq. m.

Good luck!

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

+++++++

A. I have found a simple and reliable plating solution for plating hard iron onto copper soldering tips:
1 liter Ferrous (II) Chloride 0.86 Molar (11% conc),
240 grams Ferrous Sulphate heptahydrate FeSO4.7H20, and
150 grams Sodium Citrate Na3C6H507.

I use about one cup of solution with a malleable cast iron washer in the bottom as a spent anode. Just hang the soldering tip into to solution as the cathode at about 50-100 mA and plating time and finish will vary with temperature and current. This produces a very hard and durable iron finish at low temperatures.

Michael Guerre
- Claremont, California USA


+++++++

thumbsup2Thanks a lot, Michael!

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


++++++

RFQ: I am looking for a source for iron plating of copper for custom solder tips we make in-house for our soldering department. various shapes and sizes though the largest is about 4" X 8" piece.

We are looking at individual pieces, but could send 5-20 pieces at a time.

Thanks,

Walt Rdeleted
Metal Fabrication - Croswell, Michigan
outdated



+++++appended

Q. Sir,

We are manufacturers of soldering and de-soldering stations. Since we need long life iron plated soldering bits and de-soldering nozzles we request you to kindly let us know the plating process involved in iron plating on copper.

1. How a plating bath is to be prepared.
2. What is the solution required
3. is there any catalyst required if so what.
4. What is the bath temperature.
5. How to avoid pitting problem.
6. What is the voltage supplied to cathode and anode and the bath.
7. Which kind of iron is to used as cathode and anode.

K. Raghu Rdeleted
mfrs of soldering and de soldering station - Hyderabad, Andhra Pradesh, India

Modern Solder Technology


+++++

A. Hi K.Raghu,

Iron plating is rather uncommon; the plating of soldering equipment being one of very few applications. The other manufacturers of soldering equipment don't seem to be publishing papers about their tricks, so it is difficult to get really good information and feedback.

We appended your inquiry to a thread which presents two possible plating baths. There are other baths available including sulfate and fluoborate; I don't believe that they use catalysts of any type; they do operate at different temperatures though; wetting agents are used to discourage pitting; high purity Armco Iron is used for the anodes.

The best advice may be to get all of the published information you can find, probably starting with the previously referenced Electroplating by Lowenheim, and the Iron Plating chapter in the Metal Finishing Guidebook; but also to investigate the possibility of buying a proprietary iron plating bath which will have already been proven by the supplier for soldering equipment applications.

You are in the soldering equipment business, yet with no knowledge of this technology? The obvious question on readers' minds is whether that is because you have the parts plated by an outside shop, or whether it's because you currently are doing a plating other than iron on the tips? If you are currently doing a different type of plating please tell us about it!

If I am misunderstanding, and you are already in fact doing iron plating, please relate your situation and difficulties rather than casting your questions in the abstract. You will attract more interest, you'll get answers that are better targeted, and your willingness to share will inspire others to do so. Thanks!

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

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A. Having performed this very application a couple of years ago, it's indeed very tricky! We used a ferric chloride bath, very hot. It's very inefficient, so gas liberation is big problem leading to, as you guessed, pits. We were only able to get rid of pits by putting a cam on the work bar to raise it up 3 or 4 inches and then drop it on the sides of the tank literally knocking off the pit forming bubbles. The actual bath formulation came from one of the above references. Good luck

Milt Stevenson, Jr.
Syracuse, New York


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That's a good point, Milt: iron baths are very subject to oxidation, so air agitation is a problem. Perhaps eductors are workable; but I haven't seen them or tried them in this application.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

sidebar
++++++

I have coated various metals metallic substrates with plasma technology. It should be possible to coat copper with iron.

H.R. Prabhakara
- Bangalore, Karnataka, India



+++appended

Q. I'm looking for some information regarding the coating of a soldering head. I'm looking to put a new soldering machine into production, but the soldering surface has to be a custom shape, so I'm unable to use an off-the-shelf tip. As I understand it, iron is the preferred material, but I'm finding it hard to locate a company in England that performs iron coatings.

Is there an alternative metal/material/process that can be used to protect the copper in the tip from corrosion by the flux? From my research, it seems that ferrous sulphate is the most common electrolyte for plating. Is anyone able to tell me about the practicalities of performing this process in-house, bearing in mind that we are not an electroplating company. I don't think a particularly smooth finish is required, but a reasonable level of join stability is needed, as it is subject to thermal expansion and contraction cycles.

Nickel is often used to prevent the solder from running up the tip, as the solder cannot 'wet' to the nickel surface. Does anyone know if chromium can be used instead of iron for the tip coating, and how does this perform in contact with the solder?

Rupert Tdeleted
- Southampton, Hampshire, England


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A. Hi Rupert. You are doing a pretty good job of figuring out what is involved in plating the tips of soldering irons. But if I were in your position I would continue looking for someone to do the plating. Bringing plating into house is not impossible but often subjects companies to an entire new set of responsibilities and harassments they are not prepared for including wastewater treatment, hazardous waste disposal, ventilation systems, employee exposure monitoring, etc.

Something that most potential users who have not been exposed to electroplating since school days may not realize is that in general you don't formulate plating processes from basic chemicals like in school; rather, there is a whole industry of suppliers who have perfected the plating solutions, and offer them as proprietary products. They can provide workable process solutions, and be of great assistance to you in planning for an in-house installation.

Good luck.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

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A. If you are talking about a small number of tips that would be of a medium size tip for electronics and are having grief finding a plating firm in the UK, you might want to take a look at brush plating. Tampon plating in your corner of the world. Talk to vendors in your country (at least 2).

adv.      

Instead of doing it all with the brush method, do the iron step in a tiny tank. This would not involve more than 50 to 100 ml. This could be used a few times and then stored in a used solution container. If your laws are similar to the USA ones, you can keep the small amount generated for a very very long time and then ship it off for proper treatment. Their smallest rig that is above the plating pen size would do you nicely. Probably would only take 5 amps. Plan on sending a competent person to their school that is typically 2-5 days.

James Watts
- Navarre, Florida


+++

A. Iron plating of solder iron tips is still the best finish. Electroless nickel is used for de-soldering. Iron is also plated from an HCl, ferrous chloride solution at 90 °C plating. Not a nice solution to have in a shop. There is also ferrous sulfamate that plates at pH 4, but it is little used mostly because people don't know very much about it.

Don Baudrand
Don Baudrand, Consultant
 
Poulsbo, Washington

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