On 30 Aug 99 at 11:30, Donna Perry wrote:

> Would one of you have a "few moments" to explain to
> me, a pcb designer, how bare board testing is set up
> using gerber data?

Usually the test house or manufacturer generates a netlist for his
own testing equipment from the Gerber data you supplied. As it is
only dumb graphic, if you have a "graphich" short in your Gerber
data, it would be testet as "good".

> Wouldn't a customer -supplied netlist be a better tool?  How many pcb mfrs convert
> a customer netlist into IPC-D-356 format?

Yes, but......
If you can manage that your CAD SW produces good netlists (like
IPC-D-356), you can try it. Would be much better, because this is the
netlist as you want your board electrically, and any graphic shorts
in your Gerber data would be shorts, tested against this netlist.
It you need some workaround (like forced shorts for let's say
connecting two by netlist separated grounds, not many CAD packages
handle this well), the trouble begins: You must explain yor fab
that he will find in all good bare boards exactly this (and
hopefully no other) short by default.

>
> I am asking because of a short that escaped
> detection during all fabrication processes,
> including the automated design process.
Seems the short was in the Gerber files already (see above).

HTH, regards
Matthias Mansfeld
-----------------------------------------------
Matthias Mansfeld Elektronik
* Printed Circuit Board Design and Assembly
Am Langhoelzl 11, D-85540 Haar, GERMANY
Phone: +49-89-4620 0937, Fax: +49-89-4620 0938
E-Mail: [log in to unmask]
Internet: http://www.mansfeld-elektronik.de

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