Kimmey, Frank wrote:
>
> The consensus was to call out all needed data in the Master
> Drawing, this said I would like to request if possible some assistance
> with the proper notes. If any of you have some controlled impedance
> notes you would be willing to share I would appreciate.

        Hi Frank -

        We use something like this (am away from my desk so I can't
        parrot the real thing):

        First, we identify the impedance line widths with comments
        in the aperture list, if we're doing rs-274D.

        Then on the fab drawing we show the stackup we used in our
        calculations, proving to ourselves that the impedance
        was possible.  We mark this with copper weight, distances,
        line width, and impedance.  Be sure to call this "reference".

        The note reads something like:  Impedance:  Design requires
        nominal impedance of 50 ohms +/- 10% on layers 3,4,7,8; see
        stackup chart.  Vendor to adjust line width and stackup values
        to suit process and available material thicknesses.  See
        aperture list for specification by D-code.  TDR test required.

        The aperture and TDR comments are only used when applicable.

> Thanks in Advance

        You're quite welcome!
--

      Jeff Seeger                         Applied CAD Knowledge Inc
      Chief Technical Officer                  Tyngsboro, MA  01879
      jseeger "at" appliedcad "dot" com                978 649 9800

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