John,

Let me add to what Jeffrey has said by pointing out that the plated thickness uniformity must be reasonably close so that the values you are assigning will have validity.  I've seen plated thickness uniformity vary from 1.1 mils to over 3.0 mils on the same board.  I hope others will weigh in on this because I'm told plated thickness can significantly affect the impedance values.

Roger Mouton

EIMC - Advanced Plating Technologies
949 481-5194
www.smartcatshield.com
[log in to unmask]



-------------- Original message from Babcock John <[log in to unmask]>: --------------


> Hi All,
>
> When figuring impedances with the field solvers...for the external layer
> copper thickness does one enter the finished plated value or the
> unfinished?
>
> If you specify a top and bottom layer as 1.5 oz plated to 2 oz, which
> value would you put into the field solver for the impedance calc?
>
> I would figure you put in the finished plated value...but not positive.
>
> Thanks!
>
> John
> PCB Designer III
> Isothermal Systems Research
>
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