[SI-LIST] Re: Conductor loss reduction at High Frequency

  • From: "Kevin G. Rhoads" <kgrhoads@xxxxxxxxxxxx>
  • To: olaney@xxxxxxxx
  • Date: Thu, 30 Aug 2007 23:26:32 +0000

> "silver tarnishes easily"
>So does copper, which is why standard PWB practice is to either plate
>over it or solder mask it or both.  Silver flash would need solder mask.
>I don't think the HT semiconductors etch very well, being ceramic and
>all, but if you go for the 4 Kelvin metal ones, lead traces would melt
>when you tried to solder.  Niobium-Tin costs more, but maybe it's more
>amenable to a multilayer process.  What are your other suggestions?

Well, while copper tarnishes, it doesn't as easily or as fast as does silver,
and silver can tarnish even UNDER certain coatings.  

But mostly I was trying to say, with some humor, to the OP that concentrating
upon a "better" conductor material than copper is usually and largely a total
waste of time and effort.  Yes, there are some exceptions, e.g., CeBAF, with
superconducting resonating cavities.  But, usually the improvement is from
conductor layout, and surface finish, and avoiding surface contamination on
the conductor side, and on dielectric losses & other non-conductor related 
loss issues (e.g., mismatch, or excessive VSWR for RF).

So, my suggestions were to NOT look at the conductor materials, but to
look elsewhere, such as the many excellent suggestions in other posts.
But rather than just TELLING the OP that, I thought perhaps I could provide
sufficient information that OP could/would realize the truth of it directly.

Knowledge gained that way means more, helps more and tends to stay with 
people.  Just telling someone the answer is less effective (and others
were doing that quite excellently).
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