Hi, Peter,

There is an acceptance standard for the manufacture of boards
(MIL-PRF-55110F) that defines how close the manufactured trace width should
be compared with the nominal design width. It also defines the amount of
undercut permissable, and so on. Is your problem a process problem or a
field problem? If it's a process problem, you could have a board
manufacture problem (trace width variability and/or excessive undercut,
poor lamination of copper to substrate).

What environment are your boards operating in? We're designing boards at
the moment for use in a fighter aircraft where the temperature range is
considerable and the vibration levels are quite high. The designer wanted
to use 6 mil traces at first, which suited the board electronically, but
when operating environment was taken into consideration, we increased the
trace width to 10 mils. We reckoned that very narrow traces wouldn't stand
the expansion and contraction of the board over the operating temperature
range. Could this be your problem? If it is, you are probably faced with
re-routing the board.

Sorry I can't be more help.

Pete Duncan




                    peter lee
                    <ppwlee@YAHOO        To:     [log in to unmask]
                    .COM>                cc:     (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
                    Sent by:             Subject:     [TN] Broken traces
                    TechNet
                    <[log in to unmask]
                    ORG>


                    07/26/01
                    01:16 AM
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                    peter lee






Does anyone know if there is a min. acceptance
standard for the copper conductors on PCB,
specifically on the traces width?

I am encountering partially broken traces on a board
and thinking at which point should I start looking at
the option of repairing.

Rgds,
Peter


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