Jeffrey,
I would think that you would use the same temperature raise as
an internal trace. Get the trace equivalent of the via and equate it
to a trace sq. in. There is more to it than that, but essentially that's
what it is.

Hole Dia *PI = width * (holeplating/2) = sq. in

I've got a hole to trace utility in the resource.xls file
at www.robertsondne.com It has served me well.
You should be able to use it online.

Chris Robertson
Robertson D & E
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www.robertsondne.com

Try the NEW Trace & Space Wizard! Only $25.00!!!
Calculated Trace & Space from 2 simple attributes.
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> I am in a situation that blind vias may be required to allow a PCB to
route.
> The questions are (1) how do blind vias function in a high temperature
> system (ambient 65 deg. C +), and (2)  Are they reliable for higher
current
> circuits , ~4 to 7 Amps.
>
> TIA for any input.
>
> Jeffrey A. McGlaughlin, C.I.D.
> Sr. PCB Designer
> Battelle Memorial Institute
> Columbus Ohio
> [log in to unmask]