At my last job, had a very nice excel file that calculated this all out....im sure I have it someplace but can't lay my hands on it right now.  But it was on the web...it it conformed to the standards.
   
  Now, if you guys haven't looked at www.pcbstandards.com, take a gander.  Its full of good stuff, including a bunch of calculators, etc.  Also forums for different design packages...but not Eagle.

Gerhard Fiedler <lists@connectionbrazil.com> wrote:
  alan smith wrote:

> Remember...when you drop in mulitple via's, if you just put them in a
> straight line, the first is going to take the bulk of the current, the
> others whatever can be delivered. 

How do you calculate how much current each via carries? Aren't they just
resistors (I'm talking about DC here, disregarding inductive effects)? 

Considering such a configuration (trace on top, trace on bottom, 4 vias in
a straight line):

+----+----+----+----...
| | | |
...----+----+----+----+

Why would any of the vias get more current than any other? If it is in fact
the first, which one is the first -- the left or the right?

Gerhard

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