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topic 35202

Silver Plating per QQ-S-365 Type 2 Grade A

A discussion started in 2000 but continuing through 2018


Q. I have to silver plate Aluminum 6160-T651 and Invar 36 to be used in high frequency telecommunications equipment. Should the base metal be plated with electroless nickel or copper and why? Will these migrate through the silver? I had parts that came in certified QQ-S-365 [link by ed. to spec at Defense Logistics Agency, dla.mil] {Ed. note: this spec was cancelled in 2001, with a note that "Users may consult ASTM-B700"} . The chromate makes them unusable.

1) It there an in-house test we can do to tell which parts have the chromate and which have bare silver?
2)Can we strip the parts and re-plate them to the same desired finish?

Is there a protective finish that will degrade the conductivity less than chromate? Is matte finish more conductive than the bright and semi-bright?

Steve Bowman
- Palo Alto, California


A. Dear Steve

For high frequency telecommunication parts a matte finish is better than a bright or semi bright. The best is a silver bath without any organics or metallic (except silver naturally) components. The deadening of high frequency current strongly depends on the conductivity of the surface so any passivation you use will increase deadening. Regards Marcus

Marcus Hahn
- Sachseln Switzerland


Q. Hello Marcus Hahn,

Just want to know if the silver plating QQ-S-365D Type3 GradeB can have a nickel undercoating? If so, what is the preferred thickness? How do I test on silver after amadeya42?

Thanks and best regards,

Antonio Bonagua Mayo
I.E.T.I - Manila, Philippines

Anti-Tarnish Finish for Silver - Electronics


Q. I am an Mechanical Engineer in the electronics industry and I am looking for a long term Anti-tarnish finish for silver. The application is on connector contacts. Base metal is Beryllium copper, finish is currently
1. Nickel plate 100-200 microinches per SAE-AMS-QQ-N-290 [link by ed. to spec at TechStreet] .
2. Silver plate 50-125 microinches per QQ-S-365.
3. Then 2 Minute anti-tarnish immersion in Tarniban.

I found that Tarniban is a temporary anti-tarnish finish, mostly for prolonging shelf life.

I know that QQ-S-365, grade A requires a tarnish-resistant treatment of chromate. Would this be the best finish for electrical contacts and the body of test connectors that are handled often?

Chris La Caze
- Kent, Washington USA

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What is the Silver QQ-S-365? How do I test on silver after amadeya42


Q. Our silver amadeya42 process is a 2 step procedure. I would like to know of the Silver QQ-S-365 test and how to perform it on some of our product after the amadeya42 process to gauge its tarnish resistance.

Eagerly awaiting any suggestions, info or thoughts.


Israel Ortiz
Jody Coyote - Eugene


Q. I am not in the plating business myself but my company manufactures electronic microwave (waveguide) components that need to be silver plated per spec: QQ-S-365 [link by ed. to spec at Defense Logistics Agency, dla.mil] {Ed. note: this spec was cancelled in 2001, with a note that "Users may consult ASTM-B700"} Type 2 Grade A.

The quality of the plating is very critical to meet the electrical performance of my product. We are dealing with 2 or 3 local plating shops and the quality varies between them although all say they fully comply with the specification. One new supplier asked me if the underplate should be sulfamate nickel or electroless nickel (base material being invar), I had no clue. Also, when the finish is matte I know the parts won't work well. I read that Type 2 Grade A means semi-bright finish with anti-tarnish, is there a better way to specify it? I know these may be trade secrets but my goal is to develop at least 2 reliable suppliers that I can turn to when I need this done fast and well.


Robert Dufour
Millimeter Wave Technologies Inc. - Montreal, QC, Canada


A. From what you say it looks like you are giving enough information for your platers to produce a consistent product. You may want to state a maximum roughness, this may help to make the product even more consistent.

You should also note that QQ-S-365 was cancelled in February 2001 and that the recommended specification to use is ASTM B700 [link by ed. to spec at TechStreet] (came straight off STINET, no secret inside information here). Don't know a lot about the ASTM, I haven't read it, but for future contracts you may wish to review this specification and see if it meets your needs.

As for undercoat, my preference is for electroplated nickel, electroless nickel should be perfectly acceptable though, preferably with a low phosphorus content. This part comes down to what you are used to using, I have always used an electroplated undercoat, hence my preference.

Brian Terry
Aerospace - Yeovil, Somerset, UK


A. I would agree with Brian that an electroplated nickel would be a good underplate. As for the surface finish, it will vary between plating shops, the main reason for this, is that different plating shops will use different suppliers for their plating solution, and so the chemical makeup will be different, i.e., brighteners and additives.
If you are getting a very dull, matte finish perhaps their plating solution was low on brightener that day? One of the components we make and plate is for smoke alarms, and they specify the finish must be "Bright and free of blisters"
Perhaps your company would benefit from a visit to the local plating shops to explain the components application and that it needs to have a bright finish and not dull; they will then know for next time they are plating to check their brighteners. Just some advice from my past experience with different finishes from different plating shops. Hope it helps you to understand a bit better why finishes of the same type still vary visually.

Shaun Moore
HV Wooding - Kent, UK


A. I would suggest using a cyanide copper strike, followed by an acid copper for brightness (silver doesn't stick to nickel very well) this will eliminate adhesion and most likely brightness problems.

Gene C Johnson
- Tucson, Arizona

To minimize searching and offer multiple viewpoints, we've combined multiple threads into the dialog you're viewing. Please forgive any resultant repetition or failures of chronological order.


Q. What is the spec for QQ-S-365 [link by ed. to spec at Defense Logistics Agency, dla.mil] {Ed. note: this spec was cancelled in 2001, with a note that "Users may consult ASTM-B700"} type I Grade B? I m a supplier in Asia and I'm currently looking for the detailed description for this type of silver plating. Please advise me on it. Thanks a lot!

Heather Huang
- Taiwan


A. Hello Heather,

The US government's ASSIST (Acquisition Streamlining and Standardization Information Site)web page is a great resource for finding those strange specs with a SS or QQ or LL, etc.

I ran a quick search of QQ-S-365 and a result came back that said revision D was discontinued in 2001: http://assist2.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=50980

Notice the document refers you to ASTM B700 [link by ed. to spec at TechStreet].

Good luck,

Jake Koch
G. J. Nikolas & Co., Inc.
supporting advertiser
Bellwood, Illinois
nikolas banner ad

January 19, 2018

Q. Looking for anti-tarnish plating per QQ-S-365 that can withstand high temperature up to 450 °F and that is applied anodically.

Brijesh Patel
- LA, California, USA

January 2018

Hi Brijesh. Please detail your situation. It is hard for me to understand why it is a necessity that the anti-tarnish coating you want must be applied anodically :-)

Are you an end user seeking a plating shop to apply this coating on your parts? Are you a plating shop looking to buy this process chemistry so you can apply it? Are you a generic chemical supplier trying to supply something to plating shops similar to what they are currently buying from others? Thanks.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

January 22, 2018

RFQ: Thanks for your reply. I am end user seeking a plating shop to apply this anti-tarnish coating on parts.
After plating part per QQ-S-365, some area of part is painted with black paint that needs baking at 450 °F for proper adhesion. With my little understanding of anti-tarnish plating, I believe most organic type anti-tarnish plating are applied by dipping process and usually disintegrates or evaporates at approx. 170 °F. I believe anti-tarnish plating applied through anodic or electrolytic process tend to have high temp tolerance and that is why I am looking for anti-tarnish plating that is applied through anodic process.

Brijesh Patel [returning]
- LA, California, USA

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