Electroplating of iron onto copper (soldering iron tips, etc.)

A. Hi Tim. I give the formulation & operating conditions for one iron plating bath on this page; and other readers offer several other proposals on this page and on 3 other long threads on electrodeposition of iron, viz., topics 9456, 24616, and 25982.

But! ... that sounds like the easy part!   :-)
... because I'm not finding any info about electroplating onto bismuth, and I don't know what pretreatment sequence is required, nor whether there are reactions with other metals which dictate required plating underlayers.

So plating iron (with the aggressiveness of that solution, its propensity for pitting, its requirement for no air agitation, its high stress, its porosity, etc.) directly onto bismuth sounds quite unlikely. If you have achieved success in plating another metal onto bismuth please tell us about it and we can start from there because that should probably be plated onto the bismuth as an underlayer first :-)

Luck & Regards,

A. Hi again, Tim. Thanks for the info on plating onto bismuth -- I'm unfamiliar with it and did not see anything readily on google.

I'm not familiar with iron-zinc plating if the order of the metals implies that you are talking bout more iron than zinc. Zinc-iron plating (much more zinc than iron) is an alternative to plain zinc plating and offers improved corrosion resistance plus enhanced ability to do black chromating on it.

Luck & Regards,

Q. For those with an interest in the history of iron electroplating, this article on the subject was in the Nov 27, 1869 issue of Scientific American. An interesting note is of the addition of a small quantity of gelatin to "improve the texture". Could this suppress pit-forming bubbles?

A. Hi John. Thanks for the history.

Plating solutions often (probably usually) have at least two addition agents: a brightener and a wetter. The 'brightener' (or combination of brighteners, levelers, etc.) usually serve the general purpose of being attracted to and 'shielding' the high current density areas to improve the leveling and to promote the formation of more adatoms discouraging the growth of large metal crystals (which creates porosity where the crystals meet). The 'wetter' is usually some sort of detergent that reduces the viscosity, surface tension, etc. so that the hydrogen gas bubbles float free sooner. I can't really say the role of the gelatin for sure, but I believe it probably served as a brightener rather than a wetter.

Luck & Regards,

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 onto soldering irons.

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, or scholar.google.com if you don't have access to such databases.

Or start by telling us what you know and don't know -- that always generates much more enthusiastic responses than a request from a stranger for a unilateral technology transfer. Good luck.

Regards,

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 sulphate 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 ⇦[this on eBay , Amazon, AbeBooks affil links] , 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 have no knowledge of this technology? The obvious question on readers' minds then is whether that is because you are having 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 you are already in fact doing iron plating, please relate your situation and difficulties; your willingness to share may inspire others to do so. Thanks!

A. Having performed this very application a couple of years ago, it's indeed very tricky! We used a ferric chloride ⇦this on eBay or Amazon [affil links] 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

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.

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.

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).

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.

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.