Re: Eagle CAD and 672 pin TBGA ?

On Wed, 2005-10-19 at 01:10 +0200, Markus Zingg wrote:
> >I would suggest a multi-gate symbol for such a large device. I've done
> >up to a 476-pin FPGA in Eagle and there is no reason why you can't go
> >higher. But I think you will want smaller symbol chunks to be useable.
>
> Do you think I could get away with the fan out without using blind
> vias?

You can do it if you have enough layers. I don't know the device you
are using. Typically there will be a bunch of inner pins that will all
be power or ground. These just need to go to vias obviously.

You will need (n-1) layers where n is the number of I/O rows. This
assumes that the middle all ground and power and the outside rows are
all I/O. Basically you can access the top two rows with the top layer
(no vias required) and then you'll need one layer for each additional
row. If you don't use every I/O pin you may be able to optimise.

FPGA's have the added benefit that you can pick your pinout as well to
reduce vias. Vias take lots of space.

I posted a pretty extensive suggestion on routing BGA's with eagle on
one of the CadSoft forums in response a posting from larwe (small
world!). Check it out as it has a few lessons I learned that you might
be able to avoid.

> >To place different "gates" as eagle calls them (really just one of
> >multiple symbols used in a device) use the invoke command. It will show
> >you which symbols need to be placed and which have already been placed.
> >
> >I have a BASH script that is going to be part of a tool set I'll be
> >releasing for Eagle (sort of a power tools-like offering) that will
> >generate an Eagle script that will create your FPGA footprint in about
> >10 seconds or less. Perhaps you'd like to be a beta-tester?
>
> If it saves me time - of course! My reply e-mail address is valid /
> working.

I'll email it to you, let me know what you think.

> >You will need a new license upgrade to get to 4.1 from 4.09. CadSoft
> >has a bit different view on version numbers than most other software
> >companies. But the good thing is that you only have to pay incremental
> >prices and not the whole price again.
> >
> >You'll have to check the list of fixes to see if there is anything you
> >need. 4.09 might be OK for you.
>
> As I can see now, only blind vias would be missing but provided I will
> not end up being traped in a dead end with eagly, I'm fine with
> upgrading. If they only could implement some kind of online upgrade
> option. Sending in the license certificate and then waiting for the
> upgrade to arrive by snail mail is really not so cool.

Agreed. You can download the latest version from the web so all you
need is the license disk and code. They should be able to email the
code and disk contents to you if you're in a big hurry. But if you
aren't going to use blind/buried vias than you can upgrade at any time
really.

James.

.

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