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Mentor
Mentor
3,190 Views
Registered: ‎06-09-2011

Spartan6 BGA pad footprint SMD or NSMD

Hi all,

 

I am designing a board based on SP6 FPGA (XC6SLX25-2FGG484I). I have reviewed some reference boards like SP605 and read ug112 document for recommanded pad size.

 

figure_table.jpg

 

According to UG112 for this package - FGG484 - I should use a 0.4mm pad size with solder mask of 0.5mm. This method - NSMD - is recommended by Xilinx in UG112 as shown below:

 

recommandation.jpg

 

When I look at SP605 which is a Xilinx reference board I see below pad information:

Package: FG484

BGA Pad size: 0.51mm

SolderMask & PasteMask both: 0.51mm

 

The above values imply that Xilinx has used SMD method for their own board insted of NSMD pads!.. Now, I am confused which one I am better to use in my PCB? Can anybody clarify the reason why Xilinx recommands something and uses another thing?

 

I would appreciate any help on this issue.

 

Thanks in advance,

Hossein Moradi Sarvandi

Thanks,
Hossein
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Xilinx Employee
Xilinx Employee
3,173 Views
Registered: ‎01-03-2008

Re: Spartan6 BGA pad footprint SMD or NSMD

The data sheets and user guides are always the definitive answer on Xilinx requirements and recommendations and in this case that is the Spartan-6 Package and Pinout User Guide UG393 Appendix A.  

 

The board files are static implementations and may be out of sync with the final production specifications or may deviate due to other requirements which in this case is an optional socket.

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