Re: bga routing

pd,

Spartan 3 latest atmospheric neutron readout is 6.3 FIT/Mb. It is still decreasing.

The LANSCE cross sections were less than half V2.

S3 is not recommended for heavy ion applications (space) as there is no mil version with epi wafer.

CERN uses our parts to instrument their beams.

Many labs use our parts.

Unless they are actually near the beam, there is no radiation issue.

If they are near the beam, total dode, and upsets, can be determined, and then mitigated by design.

I leave you with the following: Xilinx FPGAs today allow the engineer to design to, and meet, any arbritrary MTB or FIT rate through the use of various techniques. Doing this some other way is extremely painful, and can not be verified until you are completely finished (when it is too late).

For example, when you think you have a robust design, we have a tool which can go and change individual bits, one by one, or at random. With beam time at more thanb $400 an hour, it is a lot cheaper to verify resiliance to upsets on your bench where you can find it, and then fix it.

Austin


pbdelete@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx wrote:

I have been doing it last 6 years or so on 1.27 mm pitched BGAs
on two signal layers (top and bottom), planes as necessary (actually
6 in all cases so far), 3 lines between BGA pads, pitched 10 mils
(say, 5 mils trace and 5 mils gap, these may vary to 4-6 or 6-4).
Pad to gap is 5 or even 4 mil, drilling is 0.3mm or 0.2mm (I leave
this choice to the PCB house). I drill each BGA pad so I can have
access to all signals since my borads are typically expected
to begin to work and sell from revision 1; I have posted some
info before on how to avoid problems with the drilled BGA pads.


I saw you'r doing radioactive measurement equipment. How do you handle the
fpga sensitivity to radiation ..?

.

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