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topic 34821

Gold flash vs. plate

A discussion started in 2005 but continuing through 2019


Q. I'm wondering whether there are any standards regarding what thickness of gold constitutes "flash" and what constitutes "plating". In particular for the terminals/pins on connectors.

Thank you.

Bruce J [last name deleted for privacy by Editor]
cables - Santa Ana, California, USA


Those terms are meaningless.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg, South Carolina


A. In electronics plating these terms are not recognized.

In the jewelry industry there are distinctions for "flash", gold plate and heavy gold electroplate.
"Flash" refers to thicknesses less than 7 millionths; gold plate, above 7 millionths; and heavy gold electroplate, 100 millionths of an inch. All measurements are expressed in terms of 24 karat gold.

John Carlotto
E. Providence, Rhode Island


A. G'day, The term flash means to just cover the job with enough gold to give it a uniform color. Usually a cyanide gold. The term plating is short for electroplating. Connectors have varied uses. Some require more gold than others. Most mobile phone connectors have a thickness of 1.25 microns near the tip. Most connectors are electroplated in an acid hard gold first. This gold is an alloy and offers better mechanical wear protection. Then a flash of 24 kt cyanide gold to give it an even color.

Richard Bancroft
- Carrum, Vic, Australia


A. Flash gold plating is less than 0.25 Microns and usually not done on connectors. For this purpose, Cobalt or Nickel hardened additives are used in the Acid gold bath and usually a thickness of >1.0 Micron gold is deposited and is subjected to tests such as contact resistance, wear resistance, porosity etc.
In this case Mr. Bruce J has to set his requirement first.

t k mohan
T.K. Mohan
plating process supplier - Mumbai, India

December 20, 2012

A. Bruce:MIL-DTL-45204, Paragraph 6.3.1 defines a strike/flash as any plated material under 10 micro-inches or .000010. Depending on your application, we see 30 micro-inches of gold commonly on commercial connector applications. Mil-specs such as 39029 are 50 micro-inches min but also allow localized finishing. We routinely process size 16-22 gauge pc tail contacts and sockets with copper flash, nickel 50 min, gold flash/strike overall then selective plating mating end of socket or contact.

Casey Weizel
Foresight Finishing LLC
supporting advertiser
- Tempe, Arizona

Foresight Finishing

To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)


Q. Is there a Standard that defines gold flash?
IPC J-STD-001D [affil. link to spec at Techstreet]3.9.3 calls for gold removal on parts with >2.5 microns of gold on through-hole components and terminals. Spec sheets don't give the gold thickness, some do refer to gold flash. We use HASL in our Class 3 process, so this is an issue.

IPC calls for gold removal from 95% of all surfaces of surface mount devices regardless of gold thickness. So we have to double tin.

Thanks in advance for any input received.

Carol S [last name deleted for privacy by Editor]
aerospace - Lindsay, Ontario, Canada

May 23, 2008

Q. Thanks for above explanations.
Then, can anyone teach me what is the difference between coating and plating (using on connectors)?

Golo Wu
- Taipei, Taiwan.

Digital version

(No longer published, but a copy is on
Download it before it disappears.

May , 2008

A. Hi, Golo. These are imprecise terms, and context dependent, and people don't always use them consistently -- so it is not a good idea to try to put too fine a point on it. A "plating" is often applied by electroplating/electrodeposition and is usually a metal, whereas a "coating" does not imply what technology was used, nor that the material deposited is a metal or non-metal.


Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha

December 13, 2012

Q. Can anybody tell me if the bath/machine used for micron plating is different than a flash plating bath? If so, could you tell me the difference?

Thank you in advance

Steve Fisher
- New Zealand

December 14, 2012

A. Hi Steve. The problem is that these terms have no accepted meaning, as you can see from the earlier discussions. So how can we put a fine point on them? :-)

But to some people, "micron plating" means gold plating to a thickness of approximately 1 micron thickness (i.e., 40 millionths of an inch) for gold plated sterling jewelry or other high quality costume jewelry. I would consider this thickness to be significantly greater than a flash plating, which would be more like 7 or 10 millionths of an inch -- just enough to give color. And I would use the term micron plating only to describe gold plating, not plating of other metals.

Yes, you can easily deposit either 7 millionths or 40 millionths from the same gold plating bath and the same machine, although there may possibly be some "color golds" that might not do well except within tight thickness parameters. Good luck.


Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha

February 10, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Good evening

I am Interested in a Chain of Stainless steel with VERY thick Gold Plating (more than 20 microns) that supports scratches without going all the gold of the Surface.

So I contacted a Jeweler's shop in China and they tell me that they can do with 50 Microns gold plating but it will be Expensive.

My question is, is normal gold plating 2-3 microns but 50 is too much right for one Chain?

And do you think it's really possible to make that Thickness?


Martin Martinez
Student - Montevideo, Uruguay

February 12, 2013

A. Hi Martin,

50 microns of gold is certainly possible, even thicker coatings can be obtained. The platers in China are correct though, that is going to be very expensive.

Thickness is dependent on what you want it to do, but a thick coating for jewellery chain is more like 5 microns rather than 20 microns.

Brian Terry
Aerospace - Yeovil, Somerset, UK

March 9, 2013

A. Normally I am used to have open calculations when talking gold plating, but I would certainly check if 50 microns actually was applied.

Bo Konig
- Aalborg Denmark

March 11, 2013

A. I will agree with the other respondents and say 50 microns of gold is very possible. I once worked for a company that plated more than 127 microns of gold on electrical contacts. One thing I will tell you is that it will not be shiny gold when you are done. Also when plating those thicknesses of gold the bath has the strange and inexplicable ability to keep drawing current while the metal deposition stops completely. We never figured out how this was done. We just knew that every 5 microns or so (.0002") we would have to pull the rack and run it through an acid reactivation cycle and then continue plating. A real pain in the derriere.

Tim Hamlett
Tim Hamlett, CEF
aerospace metals distributor - Tamarac, Florida, USA

Tim Hamlett
Anodizing - Pompano Beach, Florida, USA

April 22, 2013

Q. Hi, what is the difference if I will use 30 microns of gold instead of 50 microns? Do you think any problem would occur? Anyone please answer.

Jayson Pamienta
- Naic, Cavite, Philippines

April 25, 2013

A. Hi Jayson,

You really need to give us a lot more detail about what you are using the gold for, rather than asking an abstract question. All I can tell you at the moment is that your gold will be 20 microns thinner!

Brian Terry
Aerospace - Yeovil, Somerset, UK

October 9, 2013

Q. Just a question for all talking about plating with gold --
If this process does not last long and is expensive, will you consider plating with titanium oxide using the ipg, or pvd coating process (vapor deposition system)?
Looks to me the same (gold color) and lasts longer and also you can do different thickness (for jewelry mainly).
I will appreciate any comments regarding this matter.
I do really need to know what people with more experience think.

Jorge Sepulveda
- Huntington Park, California, USA

Gold plating vs. Palladium-nickel plating with gold flash

June 23, 2014

Q. Hi! Can you please specify the difference between gold flash over palladium nickel with 30 microinches gold plating. Which is better?

Enrique Masaru
- Naic, Cavite, Philippines

June 2014

A. Hello cousin Enrique. This thread starts with a discussion of terminals/pins on conductors, and in that context an inexpensive flash of gold to protect the terminal/pins just until they are soldered or wrapped may be ideal, also a flash of gold on nickel-palladium contacts can aid in lubricity and thus wear resistance. But it has often been said that one thing is not "better" than another except in regard to meeting a list of requirements, and we don't know what requirements are important to you.

Is yours a terminal/pin application, contacts, or something else? Please give us as much info as possible about your application, and then people will hopefully be able to assist you. Thanks!


Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha

July 3, 2014

Q. These connectors that I am evaluating is being used in UPS. Regarding the functionality, I want to know if a thicker gold plating is better than gold flash with palladium nickel.

Enrique Masaru [returning]
- Naic, Cavite, Philippines

July 2014

A. Hi again. I am not a connector plating expert, and I am not familiar with what voltage and current are carried by the connectors in question in your uninterruptible power supplies, or how durable they need to be for repeated insertions and removals, so I can't answer authoritatively. But palladium nickel with gold flash was developed specifically for this application, so I suspect that it is a more cost effective approach than hard gold plating. Suppliers of the process probably have white papers on the subject. Good luck.


Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha

July 6, 2014

A. Enrique,
If cost is not a factor, I would prefer thicker gold plating. On other hand you could offset some gold cost with Pd/Ni and thin gold plating layer. Within last thirty years Pd/Ni deposits are researched and used with above objective. I also think Pd/Ni deposits possess better tribological properties than Gold deposit.

Venkat Raja
- Kitchener, Ontario, Canada

Gold plating of USB connectors

March 17, 2015

Q. I am choosing a USB connector for one of my new product developments. I need to consider gold flash plating or 15 µ" gold plating. Can someone help how to choose.

Vinay Manjunath
- Bangalore, Karnataka, India

March 2015

A. Sorry cousin Vinay, but I don't know if you are talking about adding a decorative flash of gold for the USB metal sheath (I've seen this on HDMI connectors and RCA jacks, and the Lightning end of USB-Lightning connectors), or whether you are talking about the contacts within the USB housing. I'm no connector engineer but I assume that with proper nickel plating underneath, 15 µin gold plating will meet the reliability standards for the number of insertions (I believe it was originally 1500). I think you need to read the USB specifications and insure that your design will pass the reliability requirements. Good luck.


Ted Mooney, Teds signature
Ted Mooney, P.E. - Pine Beach, New Jersey
Striving to live Aloha

Strike Hard Gold Plating

September 12, 2016

Q. Hello, All colleagues.
Please, can anyone suggest a composition for strike hard gold electroplating?
Also I need the operational conditions of this composition.
Best Regards,

Aaed Enad
plating shop employee - Iraq

affil. link
"Gold Plating Technology"
by Reid & Goldie
from Abe Books

September 2016

A. Hi cousin Aaed. Hard gold is often obtained by alloying cobalt or other metals with the gold in cyanide baths. But if you need high purity acid gold, alum and hydrazine sulphate have been reported as hardening agents but may function simply by reducing grain size according to Goldie. =>

Strikes often contain a low gold concentration in order to discourage immersion deposits. Goldie reports a strike from the 1930's with sodium gold cyanide of 6.25 g/l, sodium cyanide of 50 g/l, and HCl of 450 ml/l, but cautions how dangerous this is to prepare and that it must only be done under a fume hood. We appreciate your inquiry but there are two problems with it ...

The first is that in this country virtually no plating shops formulate their own gold plating solutions; we almost always buy from specialized suppliers who have determined over the course of decades of development what the most effective formulations are. These formulations are held as proprietary trade secret, and people cannot reveal them. If someone unknown to us were to answer you, we would not know whether their knowledge was legitimate or they are a disgruntled employee posting with a fictitious name and revealing trade secrets. So we are limited to very general info and telling you about books and published articles containing those formulations.

The second problem is that "strike" may hold a different meaning for different readers. To some it simply means a flash, i.e., a very thin plating; to others it means a low concentration bath designed to minimize immersion deposits. That's one reason why we ask people to please post the full details of their own situation rather than abstract questions. What are you applying a hard gold strike to and why? Exactly what do you mean by a strike? Thanks!


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

Flash gold fails perspiration test

February 4, 2017

Q. Dear Sir ,

We are Performing Flash gold plating prior to nickel plating on brass substrate.

base metal - brass
nickel plating - 4 microns
flash gold - 0.1 microns

After gold plating we perform perspiration test for 24 hours, and check this tape test.

We are finding some residue of gold plating on tape.
So please share the thoughts that how flash gold with stand 24 hrs perspiration test .

We do not use any lacquering procedure as it will not be feasible for us to perform.

utkarsh gupta
metal components - noida , india

February 6, 2017

A. Hi Utkarsh,
I'm not familiar with the test you mention, however, the nickel should stay active and not allowed to dry out before gold flash. If the nickel starts to dry up a bit an oxide can form and then the gold won't stick very well.

blake kneedler
Blake Kneedler
Feather Hollow Eng. - Stockton, California

April 10, 2019

Q. Hello Sirs,
Is it possible to make gold flash plating layer of 0.005 Micron thick? Or how much minimum layer thickness possible for gold flash?
I'm not more aware of gold plating, Can you guide me, please?

Arjun Chougale
- Kolhapur, Maharashtra, India

April 2019

A. Hi Arjun. Yes, it's possible to apply a gold plating layer of 0.005 Microns thick, but the question submittal form asks you:

Please DON'T post an ABSTRACT QUESTION! Introduce yourself and describe Y-O-U-R Situation.

Apologies that my answer is probably of little help to you. But I have no idea what the question actually is, and personally I am having a hard time imagining a gold deposition layer of 0.005 microns being useful for anything. Even the extremely thin gold immersion deposits are 10X this thick. Is this perhaps a homework question where you are expected to comment about the reasons for lack of utility of such a thickness? Sorry.


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

April 12, 2019

Q. Thank you, sir.
Yes, You are right, 0.005 micron layer may not useful for anything.
But we have to get just like golden appearance on nickel undercoat for electrical brass contacts instead of 0.1 micron thick gold plating.
So, can you guide me on my some queries below?
1 Is it a controllable process of 0.005 micron gold flash on nickel undercoat, or we should go for 0.01 micron?
2 Which will be better 0.005 micron or 0.01 micron thick as an only surface color concern?
3 Is it will get the same golden appearance as like 0.1 micron gold plated?

I hope to know more here. Thanks in advance.

Arjun Chougale [returning]
- Kagal, Kolhapur

April 2019

A. Hi again Arjun. You're asking for help doing something I've never heard of, sorry :-)

Why would only the 'color' be important in a electronic contact application, and for how long would it be important? Diffusion and/or wearing away in almost no time is a serious factor for very thin coatings on contacts. 0.05 micron is the thinnest gold layer I am familiar with even for an immersion gold temporary solderability protection layer, and you want to go 5X to 10X thinner than that on contacts. Why? Although I don't know for sure, I tend to doubt that a coating of 0.005 to 0.010 would even be visible.

You work for a very serious electronics company -- surely you can get hands-on tutoring from your experienced engineers on this subject which you say you are unfamiliar with? If not, yet again, tell us who YOU are and what this whole thing is about. Thanks! Good luck!


pic of Ted Mooney
Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

April 13, 2019

A. It is, of course, possible to plate any thickness down to zero.
To put this in perspective, 0.005 microns is 5 nanometres
The wavelength of visible light is 400-700nm.
A gold atom is about 0.14 nm diameter so we are considering about 30 atoms thick. With the normal distribution of plating thickness some areas would be expected to get almost none.
Such a thickness would inevitably be highly porous and require sophisticated equipment to measure it.
I cannot imagine any possible use for such a deposit.
Is it possible that someone has misread a spec or confused the units?

geoff smith
Geoff Smith
Hampshire, England

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