RF Boards Coating - RF Cafe Forums
Post subject: RF boards coating Posted: Sun Feb 15, 2004
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
Thanks a lot.
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
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?
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?
Welcome to Forum!
What is the applications
for (be specific)? If Satellite, LEO, MEO or GEO?
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!
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?
important thing is don't cover the RF paths and microstrip lines
with solder mask!!
Post subject: Posted: Tue Jun 08, 2004 10:53 am
Joined: Sun Aug 03, 2003 2:02 pm
why shouldn't the RF paths and microstrip
lines be covered with solder mask?
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
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
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
Sensitive circuits such as distributed
elements (filters, couplers etc), shouldn't be covered with solder
mask above these frequencies.
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?