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RF boards coating - 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.


Al
Post subject: RF boards coating Posted: Sun Feb 15, 2004 9:18 am
Hi:
We are developing some RF boards for space application. As usual this boards must be protected by a coating, but the material should not have any effect on the RF signal. Any advice or suggestion of supplier?
Thanks a lot.


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Guest
Post subject: Posted: Wed Feb 18, 2004 4:16 pm
The most important thing is don't cover the RF paths and microstrip lines with solder mask!!


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JGP
Post subject: RF boards coatingPosted: Thu Feb 19, 2004 8:58 pm
Welcome to Forum!

What is the applications for (be specific)? If Satellite, LEO, MEO or GEO?

Sincerely,
John Pereira


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Al
Post subject: Re: RF boards coatingPosted: Fri Feb 20, 2004 5:08 pm
Hi:
The application is for a LEO satellite. We have experience working with Low Freq. Boards in which there is not problem applying coating. Have you used Parylene coating in RF boards?
Thanks.

JGP wrote:
Welcome to Forum!

What is the applications for (be specific)? If Satellite, LEO, MEO or GEO?

Sincerely,
John Pereira


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JGP
Post subject: RF boards coatingPosted: Mon Feb 23, 2004 2:38 pm
No, I haven’t used their services. Why don’t you try them?
http://advancedcoating.com/coating.htm

Below is another one for your contact:
http://www.standardpc.com/profile.htm

I hope this will help you. Good luck!

Sincerely,
John Pereira


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va3diw
Post subject: Posted: Wed May 05, 2004 4:19 pm
hahaha. Gold is bad, solder mask is bad, special paints are high loss/high permitivity. Seriously, go to the drugstore across the street. I used the righ microwave nail polish for 20years and it works. Wish somebody would told me.


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pigger
Post subject: Posted: Tue Jun 08, 2004 2:34 am
why shouldn't the RF paths and microstrip lines be covered with solder mask?

Anonymous wrote:
The most important thing is don't cover the RF paths and microstrip lines with solder mask!!


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Kirt Blattenberger
Post subject: Posted: Tue Jun 08, 2004 10:53 am

Site Admin


Joined: Sun Aug 03, 2003 2:02 pm
Posts: 308
Location: Erie, PA
pigger wrote:
why shouldn't the RF paths and microstrip lines be covered with solder mask?


Greetings Pigger:

Solder mask is lossy (higher insertion loss along the line), and unless the dielectric constant and thickness of the mask layer is modeled properly in your simulator, the impedance will be incorrect.

For relatively short runs and frequencies under about 1 GHz, I have not had major problems with using solder mask, though. Someone with more experience might want to offer an opinion at higher frequencies.

- Kirt B.


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ck
Post subject: Past experience with coating.Posted: Fri Jun 11, 2004 11:45 am
Several years ago, the company I worked for sold a COTS telemetry receiver for use on the International Space Station. There was a need to coat all circuit boards. The receiver was P-band (under 500 MHz) as downconversion was done elsewhere. A unit earlier sold for evaluation/vibration/rad approval for the project was reacquired, and 'converted' to prove out the process.

Surprisingly, no problems were encountered. In fact, we found the noise figure of the receiver dropped slightly after mods! Later flight units were modified with no problems. For this project, a Humidseal product was approved and used.


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Itay
Post subject: Posted: Fri Jun 11, 2004 12:48 pm
At frequency under 1GHz the solder mask doesn't have any effect. It starts to affect at frequencies above 3GHz. It increases the insertion loss, there are types of solder mask which don't cause this phenomena, they are more expensive though, and required for specific applications.
Sensitive circuits such as distributed elements (filters, couplers etc), shouldn't be covered with solder mask above these frequencies.

- Itay


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va3diw
Post subject: about the bla bla blaPosted: Sat Aug 27, 2005 1:54 am
cover your resonators and transmission lines with black mud. Does it work better?



Posted  11/12/2012
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