[SI-LIST] Skin Effect, Au, and Cu

  • From: "richard moffat" <richard.moffat@xxxxxxxxxxxxxxxxxxx>
  • To: <si-list@xxxxxxxxxxxxx>
  • Date: Tue, 22 Feb 2005 09:22:54 +1300

Hi all

This discussion developed in another forum, so I thought I'd throw it
into this one to get some more comments.

For GHz signals, some people leave off the resist covering and have
traces gold-plated instead:  "At high enough frequencies (we do 18 GHZ
on rogers) the soldermask changes the impedance of the line."  I have a
bit of trouble with this reasoning, as (non-corroded) copper has less
resistivity than gold.  

I would have thought that copper at skin effect freqs would be a better
conductor than gold.  Is the loss due to the soldermask coating greater
than the skin effect loss at very high frequencies?

Cheers,
Richard

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