Keep in mind that soldermask will also change the field distributions around a microstrip line, and will somewhat mitigate the microstrip's dispersive behavior as well.
I once worked with some miccrostrip couplers at around 2-4 GHz and found that directivity was significantly improved by adding two layers of thin kapton tape on top of the coupled region, a solution that went into production. I expect that the usual soldermask layer would have about the same effect. Dana On Thu, Feb 22, 2018 at 8:15 PM, jimlux <[email protected]> wrote: > On 2/22/18 12:29 PM, Leo Bodnar wrote: > >> Here is ENIG fact that is not widely known at the moment but which some >> might find useful. >> >> I could not understand why I get better TDR and insertion loss results >> from solder-mask covered microstrip transmission lines than from otherwise >> identical microstrips on the same substrate with soldermask removed and, >> therefore, covered with ENIG. >> >> Gold can't be bad, right? As it turns out, even gold coin has two sides >> to it. >> >> I have found that Shlepnev and McMorrow conducted extensive research and >> published data, some of which is presented here >> http://www.simberian.com/Presentations/NickelCharacterizatio >> nPresentation_emc2011.pdf >> >> > the ever useful http://www.microwaves101.com/ site has an excellent > discussion of this under the "skin effect" heading. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
