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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