We've had several cases recently of boards not fitting into housings because the CM increased the board shape by one or both of the following improper panelization techniques:

1) Adding material to round board edges to make flats so they could panelize, resulting in protrusions

2) Breakaway tab design at or above board outline edges, resulting in protrusions

Then, of course, they complain about having to rework the assembled boards in the areas they changed.  You all may remember my recent post aboutthe same set of CMs that shaved the reverse mount LED pads and then complained about rework in the areas they changed.  Similar song, different day.


Not wishing to have to prepare a panelization drawing for every board, after going through a number of IPC specs and not finding a clear definition to call out on a drill drawing, I've come up with two proposed boilerplate notes:

"BREAKAWAY TABS MUST SHEAR BELOW EDGE OF GERBER BOARD OUTLINE USING LOW STRESS MOUSE BITE BREAKAWAY TAB PATTERN WITH NO PROTRUSION BEYOND EDGE."

"V-SCORE LINES MUST SHEAR AT OR BELOW EDGE OF GERBER BOARD OUTLINE WITH NO PROTRUSION BEYOND EDGE."


They also have a habit of placing breakaway tabs and score lines at edges near overhanging connectors, causing failure when the mating connector cannot fully engage due to the added material.  In this case, I've had to revise the drill drawings graphically and annotatively to specifically prohibit tab or score design.

Any IPC references I missed, and/or suggestions for improving yield that are better than what I propose, please comment.


TIA and Best Regards,
 
Gary M. Koven, C.I.D.
InVue Security Products

Charlotte, NC, USA
Board Of Directors, RTP Chapter

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