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Suitability of Nickel Plating for microwave modules - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


RFpowerJunkie
Post subject: Suitability of Nickel Plating for microwave modules Posted: Tue Feb 20, 2007 1:57 pm

Lieutenant

Joined: Tue Feb 20, 2007 1:52 pm
Posts: 3
I’m being forced down a route to adopt Electroless Nickel plating on aluminium for an enclosure that will contain a microstrip microwave assembly operating up to 12 GHz.
The RF needs to be launched onto microstrip via an SMA connector through the nickel plate on the enclosure.
Plating offered is in the range of 10 - 13 um (more than the skin depth at 12GHz) with a Phosphorous content of 6 - 12%.
It appears that for optimal electrical properties Phosphorous content needs to be 1.5 to 3%.
Can anyone advise how much the insertion loss might change from moving from an aluminium enclosure to one with Electroless Nickel plating on aluminium?
We have previously used Electroless Nickel plating on aluminium up to 4 GHz with little observable effect but are unsure what might happen at higher frequencies


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fred47
Post subject: Nickel platingPosted: Tue Feb 20, 2007 5:50 pm

General


Joined: Wed Feb 22, 2006 3:51 pm
Posts: 104
Hi!
This is just a generic response to the question, as I don't have specific experience with the exact question.

As always at frequencies in that range, surface roughness is a strong contributor to loss. Of course, the electrical conductivity of the nickel is important, too.

So the big question is, what will your surface roughness be, after plating?

Good Luck,
Fred


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Joe
Post subject: Electroless NickelPosted: Tue Feb 20, 2007 6:19 pm

Captain

Joined: Fri Feb 17, 2006 6:25 pm
Posts: 6
Location: US
I've used Electroless Nickel plating to 20GHz with no apparent degradation. In microstrip, most of the fields are confined to the ground plane of your substrate. Except for the transitions, the nickel will not have much effect. If you are looking to squeeze every last .1dB, there may be some additional loss, but in general there isn't a signifiicant difference.


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RFpowerJunkie
Post subject: Posted: Wed Feb 21, 2007 5:39 am

Lieutenant

Joined: Tue Feb 20, 2007 1:52 pm
Posts: 3
Thanks for the advice Guys.

Can anyone suggest who might be the best company to approach in the UK for plating microwave enclosures?

I neglected to say I plan to glue the microwave assemblies to the enclosure with a thin layer of silver loaded epoxy.


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Joe
Post subject: Electroless NickelPosted: Wed Feb 21, 2007 3:08 pm

Captain

Joined: Fri Feb 17, 2006 6:25 pm
Posts: 6
Location: US
Can't help on plating vendors on your side of the pond.

You didn't mention what substrate or carrier, if any, you are using. I would recommend an epoxy preform if you are going to see much temperature variation in further processing or in operation. Check the thermal coefficients of expansion for the aluminum and for your substrate and carrier.


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RFpowerJunkie
Post subject: Posted: Thu Feb 22, 2007 5:23 am

Lieutenant

Joined: Tue Feb 20, 2007 1:52 pm
Posts: 3
Substrate will be Rogers 5880 at 15" or 20" thou.

My assumption is that the surface roughness of the plated finish is largly determined by that of the Aluminium underneath and that the plating will tend to smooth the milling cutter chatter marks left in the Aluminium .


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Joe
Post subject: Posted: Mon Feb 26, 2007 4:36 pm

Captain

Joined: Fri Feb 17, 2006 6:25 pm
Posts: 6
Location: US
Once you launch to the microstrip on the 5880, most of the currents will be in the copper clad unless the copper thickness is not thick enough. I doubt that the housing finish will be a large contributor to insertion loss.







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