Our contract assembler just sent us the following message for a short prototype run on a modified design:

-------

"I asked the board house to add a 1/4" tab routed strip on the long side of the board that P1 is on so that we can put solder paste and place all of the top side SMT parts.  We need at least 4mm (0.160") for the clamping rails on the machines.  C180, C181, D1, R19 and C27 are to close to the edge of the board.
 
We will remove the strip and sand the tabs."

------------

It's a 6" x 8" 6 layer board (Sn63 soldered) with SMT parts (including a 256 ball BGA and a number of tiny QFN parts).  Apparently the EE who designed the changes and the PCB layout person were very tight on space so extended circuitry into the area reserved for the reflow oven's grippers.

Should I not be concerned that sanding could cause cracks in the solder?  The EE told me, as did the assembler, there was nothing to worry about.

This is the first time this problem has occurred since we began making products in 1980.

Should I pull the job (which is a 5 day turn) on Monday and have the artwork fixed to provide gripping areas (which used to be there) ?  

Or is it safe to do what the assembler had told the board fabricator to do?

Bob Landman

Sent from my iPhone

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________