electroless nickel for low rf attenuation?

If you want low skin effect loss, you don't want nickel of any sort. Gold, silver, and copper are the best things, with everything else a distant also-ran. Inside a cavity, electroless copper lasts a long time. It also tends to get smoother very rapidly as it gets thicker, which is also important for low RF attenuation at high frequencies.

Cheers,

Phil Hobbs

Nickel connectors also can cause intermodulation, so is not prefered in some transcievers,

Scott

DIY Piezo-Gyro, PCB Drill Bot & More Soon!

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When plating be sure you're using a good process. If you plate too fast you'll get porous films that can have a conductivity less than 1/2 of bulk. This will lead to pure perfomance. Gold is good in an wet atmosphere but if you don't need it use silver or copper. It will give you lower losses.

Depending on what you're plating to you may want to plate ~100 nm of Cr first for better adhesion.

We usually use a plating current per area density that falls in the med-range of recommended plating. It seems to give us the best results. If I was you I experiment and plate films on insulators and then measure the conductivity using a standard 4-point method. You'll need a nano-voltmeter and a constant current sourse for that. I would adjust the plating parameters until I got the highest conductivity.

Thanks for suggestions on other platings, but I am interested specifically in electroless nickel. What type of electroless nickel is best for low rf attenuation? --Grant

Grant Kiehne schrieb:

You should consider that nickel is ferromagnetic !

Therefore I don't believe that nickel is used in RF work. And maybe nobody knows which one is best :)

Regards

Sven Hegewisch

Sven,

High-phosphorus (>~10.5% by wt.) electroless nickel is non-magnetic. As I've discovered, however, it also reportedly has the lowest electrical conductivity of all types of electroless nickel.

Grant

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Why are you married to eletcoless nickel when bare aluminum is probably a better choice? If corrosion is a serious problem you have a lot of problems and unless this is a very short lived item it will probably be less expensive to go with time proven solutions such a silver plated stainless steel or copper flashed with gold.

The coefficient of terminal expansion of aluminum is going to give you fits with the cavity tuning as well.

Gordon

Gordon Couger Stillwater, OK

Gordon,

There are a number of other constraints. Without going into the details, electroless nickel is a strong candidate plating material, based on initial results. Since the electrical and magnetic properties of nickel-phosphorus deposits vary with phosphorus content, I am interested if anyone has detailed information on rf attenuation of this or a similar material. The resistivity of nickel-phosphorus increases linearly with phosphorus content, but as the material approaches the "high-phosphorus" regime of 10% by weight or higher, the material becomes non-ferromagnetic. I note that the skin depth is proportional to 1/sqrt(sigma*mu), where sigma is the electrical conductivity and mu is the magnetic permeability. I suppose one should really consider these material parameters as functions of frequency f, sigma(f) and mu(f).

Perhaps someone has encountered this or a similar problem before and could provide some guidance.

Grant

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