Hi,

Our process guidelines spec 50 mils from edge of a perforated hole.

 Our manufacturing dept. did a study several years ago after
experiencing broken
traces and exposed traces (solder mask stripped away) below the
perforations.  Some of the results from this study were that twisting
instead of snapping did cause problems, but  what caused the majority of
the problems was the temperature at which the breakaways were snapped.
The process was --as the boards came out of the reflow oven an operator
would snap them by hand.  The boards were still warm at this time.

The solution was to let the boards cool to room temperature and snap the
breakaways on a special slotted platform.  This platform was nothing but
one inch
thick wood panels that had different size slots routed in them.  The
operator selected the slot size, placed the board breakaway side down,
and snapped.  This solved
the twisting problem.  Of course this will only work with boards that
have one or
two opposite side breakaways.

Hope this helps

mike nye

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