The issue about the FPGA's footprint

[Altera_Forum]

Hi Dears: 

 I will use Altera's FPGAs, and begin designing board now. I have extracted the FPGA's footprint (FPGA1152) from Altera's devkit. I found this footprint Altera guys used has been fanned out for all balls, as attachment 1 shows.   The fanning out using the vias as attachment 2 shows. The via use the thermal relief symbol as attachement 3 shows, it isn't a normal flash symbol. So I have the question about the thermal relief symbol.  1. Why did the altera guys use the flash symbol like this?(tr0x0x0-0) I think it would be drilled away!!! 2. How to create the flash symbol like this?  Thanks in advance!

[Altera_Forum]

Usually, vias don't have any thermal relief. Possibly it's a dummy entry required by the Allegro tool (which I'm not familiar with). I don't see the question related to Altera FPGA at all.

[Altera_Forum]

Hi FvM: 

 Thanks for your reminder!