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Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

The issue about the FPGA's footprint

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!

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    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.