We are measuring a bare board. Inner layer 4 mil traces approx 6 inches long.

-------------- Original message --------------
From: "Post, Devon" <[log in to unmask]>

> Gary,
>
> It can be a problem for termination voltages, voltage divider circuits,
> power delivery, and other such critical connections.
>
> Fro example, the sheet resistance of 1/2 oz. copper is approximately 1
> milliOhm/square. If you have a trace 5 mils wide and a length of 5
> inches, the resistance should be about 1 Ohm. If it is lower, your line
> width may be larger than 5 mils. If it is higher than this, there is
> probably some kind of manufacturing defect where your line widths are
> smaller than 5 mils. Vias are another possible answer if there are any
> in the path. If there are defects in the vias it will increase the
> measured resistance of the trace.
>
> Is this resistance being measured from on top of a solder joint? If
> there is a problem with the solder or oxidation this can create a
> high-ohmic contact.
>
> Hope this helps,
>
> Devon
>
>
> -----Original Message-----
> From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of
> [log in to unmask]
> Sent: 09 October, 2006 11:24 AM
> To: [log in to unmask]
> Subject: [DC] DC trace resistance???
>
> I've never had much concern or thought a bout DC trace resistance. Now I
> have an engineer measuring 3 to 6 Ohms on a board he is debugging.
> Should this be a problem? I don't think it is. What is industry
> standard?
>
> Thanks
>
>
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> ------------------------------------------------------------------------
> ---------
> Gary
>
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