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Immersion gold plating Q&A's, Problems & Solutions

Quickstart:
     Although components are usually (but not always) immersed for plating, "immersion" plating actually means "replacement" plating. Many people have seen this in school science demonstrations where iron nails are put into a beaker of blue copper sulphate and acquire an orange or salmon colored deposit on them.
     The copper is more "noble" than iron, i.e., it exerts a stronger pull on electrons. So, when neutrally charged iron metal is put into a solution of positively charged copper ions, the copper ions grab electrons from the iron, turning the iron metal into positively charged iron ions which dissolve into the solution while the positively charged copper ions are neutralized by the electrons they have grabbed and become copper metal.
     Gold is a precious metal and more noble than non-precious metals, so in the same way it will spontaneously plate out onto not only iron, but onto copper, brass, nickel, or silver. Immersion/replacement plating is not what platers call electroless ⇦ huh? plating however.

Q. Good day how do you make 24 kt immersion gold plating solution, and method of using the solution to gold plate on jewellery.

kirtikumar devjee
Hobby - Laudium, Centurion, S.A.
May 6, 2026

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⇩ Similar, related, Q&As -- oldest first ⇩

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Q. Hi everybody. Can anyone explain why a pair of pliers would become Au plated by dipping in a Au bath although they were not connected to a rectifier. This occurred while removing damaged material on a reel to reel plating line while the line was running.

George Livingston
1998

A. An immersion plate is a possibility. Some immersion plates have a good adherence and some have a lousy one. My guess is that you formed a good enough ground to the pliers that it allowed it to plate. It is possible that the hub of the pliers was a significantly different metal and in solution, it formed a very tiny battery that was good enough to allow a very thin plate. You now own one of the most rust resistant pliers on earth  🙂 James Watts - Navarre, Florida A. The term is IMMERSION plate or galvanic plating. The difference in potential between the ferrous metal and the gold bath causes iron to go into solution. The counter reaction is the reduction of gold ions to metal on the surface of the tool. Bill Vins microwave & cable assemblies - Mesa (what a place-a), Arizona A. This phenomenon is known as immersion plating. The pliers you are using may be plated with another metal such as chrome or may be a bare ferrous substrate. Because gold is a very noble metal (meaning it is very inactive) it prefers to be in the solid metal state rather than in the ionic form which would be found in the gold bath. Iron or chrome are active metals when compared to gold so these metals will dissolve (become ionized) into the bath to replace the gold ions which will become solid (gold plate). The following chemical equation show how the basic process works in a potassium gold cyanide bath: 3KAu(CN)2 + Fe(solid) = 3Au(solid)+ K3Fe(CN)6 This can also be looked at as an electrical process (as all chemical reactions are) as electrons are passed from the iron to the gold. Gold atoms in the ionic form have electrons missing from their outer electron orbits (these missing electrons are hanging around the cyanide-CN ion) giving the gold ions a positive electrical charge. Electrons in orbit around iron atoms prefer to be in orbit around the positively charged gold atoms. This means that the gold electron orbit provides a lower energy state for the electrons than does the iron orbit and according to the laws of thermodynamics --- processes always move towards the lowest energy state. So without ever applying an external electrical power source - an electrical circuit is created in the gold bath. If properly set up you could create a gold battery - similar to a lead acid battery but with different chemistry and much more expensive. Greg Haataja helicopters - Fort Worth, Texas

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Q. I am looking for a commercial or military specification for immersion gold plating.

Mike Steele
- Cincinnati, Ohio
1999

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Need equipment for electrogravimetric measurement to analyze immersion gold solution

Q. Hello, friends,

I will do immersion gold plating by end of this year. So, I need equipment to analyze the gold content (1.5 to 3.5 g/L). Someone recommend me to use the electrogravimetric method to analyze this gold content. Anybody know that where we can get equipment to do this electrogravimetric analysis in Malaysia. Any instrument/equipment supplier have supply this equipment (in Malaysia)? ⇦ Answer?

Thank you very much for your helpfulness!

Regards,

Wymen Lee
- Penang, Malaysia
2002

Ed. note: This RFQ is outdated, but technical replies are welcome, and readers are encouraged to post their own RFQs. But no public commercial suggestions please ( huh? why?).

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Immersion Gold is not wetting Lead-Free Solder

Q. We are inserting a Gold Pin Thru Hole Connector into a Immersion Gold finished PCB.
The connector is being hand soldered using Lead-Free water soluble solder wire.
Our problem is on about 20% of the leads won't wet all the way thru to the top of the PCB.
It doesn't matter how long you hold the soldering tip to the lead or how much flux you use.
We are using a big enough tip for heating purposes I think. It is the largest that will work in the confines of the soldering area. The solder on the leads melt instantly upon contact with the tip so I think the heat is sufficient.
Any ideas what might be causing this?

Thanks,

Brandon Goodwin
- Austin, Texas
2006

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Immersion gold peeling from electroless nickel

Q. Who can suggest the reason why gold is peeling form nickel, always found gold peeling on bottom of pad close to solder mask ?

What are the possible root cause of gold peeling from nickel ?

Satit
PCB - Bangkok, Thailand
2007

A. The main cause is that the nickel surface becomes passive, and you are losing adhesion values. There should not be any delay between EN and Au. If the boards are baked after solder mask, it tends to lift the Au from the underplate. This is why you need good adhesion of the gold on nickel. Good Luck! Mark Baker Process Engineer - Syracuse, New York USA A. Firstly your question is not supported by a description of your process. How was it determined that the gold is peeling from the EN layer? Was it by means of a tape test? Generally if the peeling is at the edge of pad nearest to the solder mask, it is likely that there are there may be impurities trapped at the recesses of the solder mask. Make sure that your post rinsing after the EN plating is with DI water. This is important if your process is a continuous one where immediately after the EN process the board goes into the immersion gold tank. I am not sure if your are familiar with "Black pad". If this occurs there is a chance that the peeling between the Immersion gold layer and EN occurs. Alan Logan - Singapore

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Multiple threads merged: please forgive chronology errors and repetition  🙂

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Q. Hello, I have a problem with Au/Ni peel off. My process is immersion gold used for PCB industrial. Once a day, in process occurs problem of Au/Ni peel off. First, I was check initial this defect show as 1) After tape test found Ni peel off from Cu plate
2) I found this problem just 5 cycle continuously for mass production, next cycle not found this defect.
What is cause occurance of defect ? Thank you for any answer or recommendation

Vasin Keawmalee
Process Engineer - Thailand
November 25, 2009

Ed. note: Is it possible that you find this once per day for 5 cycles after a lunch break? As Mark has noted, nickel passivates quickly.

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Q. Electrolytic gold plating is immersion depositing on non-electrified housing.

I have parts that have hermetically glass sealed pins assembled into them. The pins are wired to gold plate. I run parts through Wood's nickel ⇦ huh? at 30 ASF, nickel sulfamate at 5 ASF and then a potassium cyanide at 5 ASF. After the gold plating the housings made of 304 SS are discolored from an immersion gold. This immersion gold causes problems down stream when we go to weld the assemblies into a flange.

Reading through this thread I noticed the mention of a galvanic reaction in the plating bath. Could this be the cause of the immersion gold? Would it attribute to nickel contamination in the plating bath?

I can perform a light gold back strip and remove the immersion gold but it's a lot of added time and it's tough to ensure all of the gold is gone from the housing. Is there a method for prevention of immersion gold all together?

Benjamin Hartford
- Laurens, South Carolina, USA
January 8, 2020

Ted, the pins are RA330 SS. I think you were right about the pretreatment process. I was using a sodium fluoride activator and I ran a trial going back to the HCl activation bath instead and the parts did not receive any immersion gold.

Although the sodium fluoride is a really good activator I think I will stay away from it for assemblies.

Benjamin Hartford [returning]
- Laurens, South Carolina USA

Q. I am diving into this project more again and facing the same issues. The problem is definitely associated to the activation and the housing staying active through the process. With previous processes I was using a weak HCl mix of roughly 17% free acidity (around 5% concentration). This low concentration HCl solution was a process hand down from the previous plating engineer. The problem with the low concentration is that it is not strong enough to activate the parts to allow for proper adhesion. Therefore parts would fail a bend test. Through all of this I have started to move towards more industry standard with a 50/50 HCl solution (50 % v/v DI water and 50% v/v 37% concentration HCl). This works great to improve my adhesion potential, but puts me back into a position where I am dealing with the immersion gold on the housing again. Now I have a customer that requires no mechanical abrasion (bead blasting) before or after plating and has suggested a reverse trickle current on the housing during gold plating, but they have been deliberately vague on how to do this. Apparently this is a common practice in the gold plating industry but there is not a whole lot of detail on how to do it. Can I use the same anode and run it as an anode and cathode at the same time? Do I have to have a separate graphite piece to act as a cathode for the reverse current? What current density should I use for this or should I use constant voltage and if so what voltage? Hoping someone with experience can provide some insight into this process.

Benjamin Hartford [returning]
- Laurens, South Carolina USA
July 14, 2022

Sorry! Finishing.com is temporarily Read-Only.
Ted Mooney is retiring but I have several offers to take it over.
We're working hard to make sure we find it the best new home.

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