•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Job Board

About RF Cafe™

Sitemap

Solder Mask on RF PCB - 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.


ashishbondia
Post subject: Solder Mask on RF PCB Posted: Fri Jan 23, 2009 10:55 am

Captain


Joined: Wed Aug 16, 2006 8:20 am
Posts: 23
Location: India
Hi!
I am designing a PCB to work from 100KHz to 7 GHz. I was almost done with my Layout and the gerber was ready for fabrication when someone mentioned to me that I should consider the effect of Solder mask.
He suggested that the Grounded CPW trace width and separation I used were valid only when I had air as the dielectric over my traces. Using a Solder mask would alter the impedance as it has a dielectric greater than air.
I quickly added a layer of Solder mask in my simulation (using Er for Solder Mask as 3.3 and loss tangent as 0.04
I found that The VSWR of my trace improved, however the trace was now more lossy.

I don't want to get rid of the solder mask as the Coplanar GND plane is just 20 mil away from the RF trace and many (0402) size components need to be soldered on them. Since I am not very good at soldering I am afraid that I would short the traces. My board is fairly large (10 inches by 7 inches) and has more than 500 components. Few traces are 1 inches long.

Has anyone faced a similar problem or has any suggestions...

_________________
Ashish Bondia,
Design Engineer- RF


Top

IR
Post subject: Posted: Fri Jan 23, 2009 5:36 pm

Site Admin


Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Solder mask at frequencies higher than 4GHz is not recommended because it adds insertion loss. Do not worry about soldering, once you start you will improve with time. But if you will miss 1-2dB gain in your Tx chain it will be much harder to compensate...


Top

ashishbondia
Post subject: Posted: Sat Jan 24, 2009 4:44 am

Captain


Joined: Wed Aug 16, 2006 8:20 am
Posts: 23
Location: India
Thanks IR
I am exploring the possibility of using Solder Dams to restrict the flow of solder on the bare traces.
However for a board having more than 500 component, the time required to create Solder dams along each pad would be large.

Along with the Solder mask another issue that is driving me crazy is that of Board Surface finish. I have a choice of HASL and ENIG finish. I have learnt that ENIG causes higher insertion loss and also degrades IMD performance.

_________________
Ashish Bondia,
Design Engineer- RF








Posted  11/12/2012
Custom Search
More than 10,000 searchable pages indexed.

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeKirt Blattenberger... single-handedly redefining what an engineering website should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5th MOB: My USAF radar shop

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website