Ernie,
1) The answer depends on the thickness of your board, what material, the type of component, how component is held to board (solder or adhesive) and distance between the component and the application of the stress.  And then what kind of engineering safety factor you want.
2) Glue strain gages on the board and measure the results.  Make sure you use a system that can "capture" the action.  We (Nortel) started out with a 1 Hz system and completely missed the actual "event". 1000Hz is much more realistic.
3) Yes, at Nortel Networks, but that is ancient history for me and was all privileged info anyway, not industry standard.
regards,
Bev Christian
Research in Motion

-----Original Message-----
From: Ernie Fung [mailto:[log in to unmask]]
Sent: January 19, 2004 12:01 PM
To: [log in to unmask]
Subject: [TN] Stress measurement on PCB


We are currently looking for a way to measure PCB / chip component stress
during our assembly process, especially depanelization. We would like to
get an idea of what amount of stress (flex) the boards are undergoing. We
would also like to use this to compare a few different processes--for
example router depaneling compared to cutter depaneling as well as manual
depaneling.
But we are now facing several problem:
1. How much "stress" (or flex) is too much, for both PCB and chip
components near the PCB edge?
2. What equipment could be used to make an accurate measurement?
3. Any simular test is done before?

Thanks,
Ernie Fung

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