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WQFN148 Usage Restriction -- 32 mil PCB thickness

Altera_Forum
Honored Contributor II
‎03-08-2013 06:54 PM
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We're using an EP4CGX15BN11C7N Cyclone IV device in a WQFN148 package on an extremely tiny board. 

 

The mechanical definition document states that the part shouldn't be used in boards more than 32 mils thick. I've never heard of this kind of a restriction. Normally thicker means more rigidity, which tends to mean better mounting reliability for QFN and BGA packages. See http://www.altera.com/devicepackaging/04r00350-03.pdf for a package definition. 

 

The part footprint is extremely challenging to incorporate into a layout. We'd prefer not having to go to an excessively thin laminate stackup. 

 

Does anyone know the reason for this restriction? 

 

Does anyone have a known good Pads layout decal for this part? (very time-consuming part to design). 

 

Thanks
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Altera_Forum
Honored Contributor II
‎03-08-2013 09:32 PM
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You'll find some information about reliability of micro-leadframe packages related to board thickness at amkor.com web site. See particularly pg 15 of this presentation http://www.amkor.com/index.cfm?objectid=42ef136e-5056-aa0a-e20f61ed99fb26f7 

http://www.amkor.com/go/packaging/document-library
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