Nice one Joe

Victor here is a link describing the effect of solder mask on trace
impedance :

http://www.sigcon.com/Pubs/edn/PassivationandSolderMask.htm


As Joe alludes it is indeed a dielectric with a typical dielectric constant
value of 3.3. You will find in RF designs that often the boards are
specified without solder mask for this very reason.

Have a great weekend,

John



John Burke
(408) 515 4992


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Fjelstad
Sent: Friday, May 08, 2009 1:11 PM
To: [log in to unmask]
Subject: Re: [TN] Solder Mask

Victor
 
How/why do you conclude that solder mask is not a dielectric? 
 
Cheers,
Joe 
 
 
In a message dated 5/8/2009 12:37:48 P.M. Pacific Daylight Time,  
[log in to unmask] writes:

Fellow  TechNetters:



Besides being a moisture barrier and solder  dam what else is the
function of solder mask.   It is not a  dielectric.



Victor,


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