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    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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RF boards coating - RF Cafe Forums

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Post subject: RF boards coating Posted: Sun Feb 15, 2004 9:18 am
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.


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!!


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?

John Pereira


Post subject: Re: RF boards coatingPosted: Fri Feb 20, 2004 5:08 pm
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?

JGP wrote:
Welcome to Forum!

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

John Pereira


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?

Below is another one for your contact:

I hope this will help you. Good luck!

John Pereira


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.


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!!


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.


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.


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


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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