This looks like a fun one and I'm sure the opinions will run strong.  
IPC's specifications for lifted lands unfortunately were wagged by the 
55110 untill they went to the 0.001 requirement.  As my buddy the late 
George Smith told me once, lifted lands could roll up like window shades 
as far as he was concerned.  Of much more importance was the integrity of 
the knee and whether it was cracked.  The rest was irrelavent.  

I would stand by the latest 276 requirements as the industry position on 
lifted lands.

Regards
__________________________________________________

David W. Bergman, Technical Director
IPC
2215 Sanders Road
Northbrook, IL  60062-6135
847-509-9700 x340 Phone
847-509-9798 Fax
email  [log in to unmask]
www  http://www.ipc.org
faxback support 800-646-0089
---------------------------------------------------


On Tue, 16 Jul 1996, Gregg Klawson wrote:

> Hello!  We're having a discussion here regarding the inspection criteria for
> PWB coupon microsection lifted lands after thermal stress.  We're just
> cutting over from military procurements to more "commercial" and are trying
> to decide what makes sense.  The specifications state:
> 
> Mil-P-55110E allows a maximum lift of 0.001 inch.
> Mil-P-55110D before ammendment 4 allowed a lift of 0.003 inch maximum.
> IPC-RB-276 states "lifting allowed" for all classes (no limit).
> IPC-A-600D allows a maximum lift of 0.003 inch.
> IPC-A-600E allows a maximum lift of ?????
> 
> What is the purpose of this requirement?  Do we need a limit?  If we need a
> limit what is the "industry standard" limit from board house and OEM
> viewpoints.  We've been calling out IPC-RB-276 class 2 with a 0.001 inch
> limit.  A couple of our board houses tell us 0.003 inch is the "industry
> standard".  Any and all comments appreciated.
> 
> -Gregg Klawson
> GTE Government Systems COrp
> +1.508.880.1822
> mailto:[log in to unmask]
> 
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