has anyone measured performance of silver plating solutions?

[coppercone2]

So I am looking to protect my copper antenna.
recommended for electronics use
https://www.cool-amp.com/order

or
random jewelry stuff
https://jaxchemical.com/shop/jax-silver-plating-solution/

I got the copper to a reflective finish now with a buff and abrasive compound, but I am wondering.... what the hell do you get for basically 3x the price?

I don't expect to get a performance boost from this antenna (it needs a ding king more then anything) but.. why the price difference?

[coppercone2]

https://irp-cdn.multiscreensite.com/5a37792a/files/uploaded/CA%20MSDS-HMIS%20ratings.pdf

sodium chloride, calcium carbonate, silver chloride

https://jaxchemical.com/wp-content/uploads/2016/07/JAX-Silver-Plating-Solution-SDS.pdf

Ammonia, Silver Chloride, Sodium Thiosulfate


so is NaCl and CaCO3 better then aqueous ammonia and sodium thiosulfate for this?

https://pdfs.semanticscholar.org/bab6/3be47615458cc3009a4149cb3067756955ab.pdf

Is the sulfate maybe a problem since it reacts with silver?

[coppice]

A silver coating will improve the losses in most RF applications, but its a poor choice for protection. Unless the atmosphere is rather dry it can corrode quite rapidly. You may see parts completely blacken in a few days in some atmospheres. In most RF applications using silver coated parts some corrosion protection measure is needed. Conformal type coatings often spoil the RF performance, so you'll see techniques like the use of desiccants in sealed RF chambers.

[coppercone2]

will polished copper hold up better?

its mainly for appearance rather then impedance

I just figured it would hold up better. it will change by so little and its not in a anechonic chamber or something so the random fields in the air will effect it more then anything

If copper will stay brighter longer, I will keep it. I just thought it was more robust.

Since I got it polished down pretty good now (needs a final pass with a green rogue) I don't mind just throwing some brasso on it once in a while. It looked like complete shit pulled out of a swamp and it worked fine. I figure it will work better looking like a trambone.

[vk6zgo]

So I am looking to protect my copper antenna.
recommended for electronics use
https://www.cool-amp.com/order

or
random jewelry stuff
https://jaxchemical.com/shop/jax-silver-plating-solution/

I got the copper to a reflective finish now with a buff and abrasive compound, but I am wondering.... what the hell do you get for basically 3x the price?

I don't expect to get a performance boost from this antenna (it needs a ding king more then anything) but.. why the price difference?

In the early days of Radio, copper was not as pure as it is today, & experimenters found that silver plating reduced losses.

Moving right along to the late 1950s, silver plating to reduce losses had become the "received wisdom".

A couple of EEs working in the Australian Postmaster General's Dept decided to find out just how much improvement was made.

They made up "Tank Coils" for the PA stage of a transmitter, one set plain copper, the other silver plated.
To their surprise, the copper coils consistently ran cooler!

It turned out that copper purity had improved a lot, but the "biggie" was that the composition of silver plating had changed.

The normal role for silver plating is to look attractive, & to be durable.
Relatively pure silver plating, as used back in the early decades of the 20th century, did not meet these requirements all that well, as it was not easy to create a really glossy finish on it, needing to be regularly re polished by hand.
It was also relatively soft, so polishing could remove material from the surface, unless the plating was quite heavy.

The electroplaters added impurities which had the desirable effects of hardening the silver & rendering it easier to polish.
It used less pure silver, so was cheaper.

Win-win?
But Oops! The added impurities increased the resistivity of the plating to greater than copper.

This is why the special stuff for electical use is more expensive.

[coppercone2]

do you think a bicone antenna out in the open would have a longer good looking life if it was coated in silver or left as highly polished copper?

Assuming I get the cool amp brand. My copper sheet is from some jewelry supplier or something so it will probably benefit its not OFE Copper


but its basically a random band antenna, I just don't want a eye sore around.. i need to make a proper broad band pancake one

[coppice]

A couple of EEs working in the Australian Postmaster General's Dept decided to find out just how much improvement was made.

They made up "Tank Coils" for the PA stage of a transmitter, one set plain copper, the other silver plated.
To their surprise, the copper coils consistently ran cooler!

It turned out that copper purity had improved a lot, but the "biggie" was that the composition of silver plating had changed.

If the silver is applied properly it brings an improvement when the skin depth is really small, because its resistance is lower than that of copper. The problem is a lot of people do not deal with the coating very well. If you look in detail at many samples of silver plated copper wire that has been formed into a tight coil you will find the silver layer has been stretched to the point of forming a crazed mass of tiny silver islands on the outside of the coil. I know forming followed by plating improves this, but I'm not a metallurgist, and I don't know the details of getting a high quality result.

[coppercone2]

I would imagine the best result is bend, destress, sand/polish, plate

metal kind of sucks when its bent (try hammering a aluminum flatbar to make a bracket, it looks like it has wrinkles.. if you just get a home depot piece of flat bar and hammer it to a right angle in a vise you really see the metal is being 'worked').. i bet heat would improve this, but usually the point of bending is to save time and heating it is obnoxious

when I saw very heavy aluminum that was press formed into brackets (1 inch) it looked pretty shady on the interior side. like a roided old man body builder 

great way to make a clamp for a screw driver or vacuum cleaner hose that you can mount under a table etc, especially considering you can cut it with bolt cutters

[vk6zgo]

The investigation the EEs carried out was formally presented in the "Telecom Journal of Australia", which was a well respected Engineering  publication.

Unfortunately, as it was a long time ago, there are probably no copies still in existence.
I only saw the paper in reproduced form, back in the1960s.

[coppercone2]

I can do VNA plots of this antenna before and after plating the exterior. Will take a while though.

[coppercone2]

https://www.dxmaps.com/discuss/silverplating.html

[Fraser]

I am just about to start some experiments with Bright Nickel electro-plating some battery contacts etc. Not RF, but I have seen plenty of Nickel plated brass and copper antenna parts in my time. Losses can be a consideration due to skin effect and nickels resistance (in some very high performance cases) but something tells me a thin coating of weather resistant Nickel is not going to be the end of the World for your antenna. Nickel plating can be effectively done with either a Nickel electrode brush technique or in a tank. The brush technique places a very thin layer of Nickel on the surface and is described as cosmetic as a result. That sounds like what you want and Nickel loves to coat copper !

https://www.gaterosplating.co.uk/

https://www.gaterosplating.co.uk/plating-kits/bright-nickel-brush-plating-kit

May be worth looking into ?

Fraser

[coppice]

I am just about to start some experiments with Bright Nickel electro-plating some battery contacts etc. Not RF, but I have seen plenty of Nickel plated brass and copper antenna parts in my time. Losses can be a consideration due to skin effect and nickels resistance (in some very high performance cases) but something tells me a thin coating of weather resistant Nickel is not going to be the end of the World for your antenna. Nickel plating can be effectively done with either a Nickel electrode brush technique or in a tank. The brush technique places a very thin layer of Nickel on the surface and is described as cosmetic as a result. That sounds like what you want and Nickel loves to boat copper !

https://www.gaterosplating.co.uk/

https://www.gaterosplating.co.uk/plating-kits/bright-nickel-brush-plating-kit

May be worth looking into ?

Fraser

If you try something like a nickel plated N-connector versus a silver plated one you will find the silver ones runs much cooler on day one. However, the nickel plated one will run at the same temperature on day 1000, while the silver plated one may have gone up in smoke on day 1000 if the atmosphere is humid. Places like Hong Kong, Mumbai and Singapore are killers for silver plated connectors.

[coppercone2]

you know I think I will also try putting grease on BNC connectors and see how that effects things to 300MHz (my VNA).

Is ultrasonic + simple green enough to remove dielectric grease for RF applications? (so I can clean my connectors afterwards without contamination). I was thinking to smear on barrel and put a tiny glob on the middle receptor.

[helius]

Silicone grease is quite difficult to remove (the "universal contaminant") so if you are planning to fully clean it I would stick with a petroleum type grease (Cosmoline or No-Ox-Id would work).

[coppercone2]

is there anything from home depot that would be good ?

I can use this DC https://www.minicircuits.com/pdfs/ZEDC-15-2B.pdf

[IconicPCB]

Coppercone,

We make printed circuit boards.

Part of our process is electropolishing of copper to a high gloss copper mirror prior to electroplating.

If you are interested in achieving a bright copper surface finish you too can use the electropolishing process....
A mixture of nitric acid and alcohol is required.

An initial current density ( may need to experiment a little bit) must be monitored for signs of reducing current.

Principle of operation   solution provides a copper etching environment with conductive path which is self healing as the surface roughness reduces. Copper surface roughness penetrates through an initial conductive barrier layer. As etching progresses current drops and that is the sign surface is polished.


EDIT that should read PHOSPHORIC ACID NOT NITRIC ACID.... my mistake

[coppercone2]

how do you monitor current? galvanostat?

does it offer a better finish then abrasive compound on a buff? have you ever measured your process to a Ra number?

any idea where the benefits would start from a microwave standpoint?

maybe a test would be a stripline filter that is polished to various grades and put into a VNA? are the numbers similar to numbers given for stainless steel electropolish?

It's nice to put on a dust mask and get some wipes and clean up the area and have waste suitable for a trash can (in regards to mechancial polishing.. nitric acid would need to give serious performance increase for it to be worth it on a hobby scale IMO unless you have a bit of cash for disposal etc. will it attack parasitic undercut on etched PCB?

also, unsuitable for ceramic PCB correct (they will dissolve in acid)? possible to mask from nitric acid if you are trying to chemically 'hone' a controlled impedance trace on ceramic? or rate if reaction of substrate is slow enough to allow the copper polish process to occur before critical damage is done? how would the substrate reaction show up on your current measurement.. or do you only do it to less reactive epoxy substrate (I assume).

[JohnG]

Cool-Amp:
I have some, and I have used it for some small parts of a large transmission line resonator (1 m long by 10 cm OD, 50 ohms). It works ok, but it is a lot of work to apply, since you rub it on, and the silver layer is very thin. The reason for the latter was explained to me by a chemist, who said that the compound works because the copper reacts more easily with the compound. When you rub it on the copper, the copper displaces the silver, which deposits on the copper. Once the copper is covered with silver, no more reaction, and no more silver deposited, so you can't get much silver. I don't know how thick it ends up, but it's thin to be very resistant to corrosion.

Nickel plating on RF parts:
It adds loss, and the loss can be considerable as the frequency goes up. I'd be really concerned about losses on an antenna, where the currents tend to flow near the surface. A connector is a short part of the system, so the extra losses will be limited to the connector.

Nickel has the added disadvantage that it is magnetic, and skin depth is proportional to (conductivity*permeability)^-1. Since nickel's relative permeability is high (> 100?), this reduces the skin depth a lot. At some high enough frequency (GHz), the permeability drops, so if you get high enough it may not be as big of a problem.

John

[IconicPCB]

Current is monitored by an amp meter...

I have no way of specifying the surface finish.

Surface roughness is to be thought as variation in electrical length of the path. As such it may contribute to skin loss( reduction in Q) and an uncertainty in electrical length important at higher microwave frequencies.
We had been asked to fabricate a cavity strip line filter in Rogers multi layer structure.
And while Rogers specify conventional multi layer pressing process to handle the material they also recommended a chemical surface treatment to enhance bonding.
We did not have access to all materials ended up pressing the filter structure and producing functional samples however hole wall activation was compromised, the bonding between layers was porous and the finished product suffered from palladium ingress into the board.
One way to enhance the bonding would have been to mechanically treat the copper prior to bonding however the result was skewing of filter performance and loss of Q due to the above mentioned effects on surface path length and skin losses.

  If You want to see the surface which is electropolished I can certainly put it through the process. May be a well known ( to You ) filter hand rubbed versus electropolished side by side shoot out?

[coppercone2]

I suppose I should update this thread in the interest of keeping everyone in doors.

Ok, so do you have a tutorial or primer on electropolishing copper?

The only process I am familiar with is electropolishing stainless steel using a conductive brush. I imagined maybe something with carbon wool or something too, or maybe a tank.

Estimates on required power supply and electrolyte composition?

[helius]

Electrocleaning solution:
Sodium carbonate 50g
Trisodium phosphate 25g
Sodium hydroxide 25g
Water 2000mL

This must be stored in plastic. Concentrated bases attack glass.

Alternative formula:
Sodium carbonate 75g/L
Sodium hydroxide 12.5g/L
Trisodium phosphate 25g/L
Sodium silicate 12.5g/L

Current density: 1 to 3 A/dm^2
Polarity: 1 to 3 minutes cathodic (at the work)
5 to 10 seconds anodic
Operating temperature: 60 to 70 °C

[coppercone2]

how good are those current figures if you want to do work with some kind of sponge? can you work small areas like stamping a document?

[StuartA]

Electrocleaning solution:
Sodium carbonate 50g
Trisodium phosphate 25g
Sodium hydroxide 25g
Water 2000mL

Could you just confirm what materials these solutions are intended for?
Thanks
S

[helius]

Could you just confirm what materials these solutions are intended for?

It should work on all metals, but note that this will leave the surface activated. You need to passivate the work if no further processing is to be done.