Peter,

I am not sure of the IPC specification for this, perhaps  IPC-276 (old numbering format)

But our PWB specification we send to any vendor fabricating rigid boards for us states;
Conductor Width Reduction
    Conductor shall not be reduced by more than 20% from undisturbed width at any location
    due to edge roughness, nicks, pinholes, scratches,  voids, and mouse bits.
Conductor Thickness Reduction
    Conductor thickness shall not be reduced by more than 20% from undisturbed  thickness
    at any location due to nicks, pinholes, scratches,  and depressions.
Under Cut allowance is defined as 3/1 ratio of conductor height and shall not be exceeded.

We inspect to this a reject all product not meeting these specifications.
We build Class 2 PWAs and do not encounter much argument from our fab houses.

hope this helps

Greg Scott
Cray Inc
Seattle,  Wa.

Bill Butman wrote:

> Hello Peter,
>
> If you do decide to repair the traces, look at
> IPC-7721, procedures: 4.1.1 thru 4.2.5.  These IPC
> approved procedures describe several methods of
> performing reliable repairs to damaged traces.
>
> In addition, web site www.circuittechctr.com has
> information on trace repair, in their "guides"
> section.
>
> If I can be of more help, please let me know.
>
> thanx
>
> Bill
> [log in to unmask]
> --- peter lee <[log in to unmask]> wrote:
> > 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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