Hi Pete,
Delamination cracks have been experienced after reflow with a number of base materials—I have not seen this on bare boards.
Moisture 'vapor' pressure has been implicated in some cases but not all.
I am not aware of any requirements' on this; clearly, the highest loading occurs during the soldering processes, T-cycling and vibration are benign in comparison.
Crack propagation would only occur of the laminated is somehow 'pulled apart;' you need to determine whether you have such loading.
Werner

 


 

 

-----Original Message-----
From: [log in to unmask]
To: [log in to unmask]
Sent: Mon, Feb 8, 2010 12:49 pm
Subject: [IPC-600-6012] Laminate Cracks


Does anyone have any information regarding crack propagation?  A bare
board is allowed to have laminate cracks as long as they are in the
non-evaluation zone or if they originate in the non-evaluation zone they
can't be longer than 3 mils going into the evaluation zone.

What is the requirement or what should I expect to see after the bare
board has been assembled and run through thermal cycle and vibration
testing?  Should there be no propagation or ???

Thanks,


Pete Menuez 
Supplier Quality Engineering Manager 
L-3 Communications Cincinnati Electronics 
7500 Innovation Way 
Mason, Ohio 45040 
[log in to unmask] 
513-573-6401 Voice 
513-573-6767 Fax 



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