What is the ball pitch? There are ways to play with both track, via, and
ball size to route the board with lots of room left to run tracks from out
side the BGA. Is the ball grid causing you to go to the 10 layer count? what
size vias are you using, what size tracks? If the ball grid has a lage
number of pads keep an eye on your power and ground you may end up taking
too much copper away with poor via placement (if power and ground are
located in the center). With a 1mm pitch you should be able to fit two
tracks between a pad using a 4/3 set up and 20mil pads and vias. You can go
three layers deep for the fist layer and two rows there after. when using a
5/5 on a 1.27mm pitch 44 signals can be routed from the 7th row.
Ted
-----Original Message-----
From: Ian Wilson
To: Protel EDA Forum
Sent: 8/13/01 6:53 PM
Subject: Re: [PEDA] Protel 99 cannot auto-route BGA components
On 11:58 AM 13/08/2001 +0000, [EMAIL PROTECTED] said:
>I have been unable to autoroute a 10 layer design which has 2 fine grid
>BGA packages. Protel support has not been able to assist me and has
cause
>a 3 MONTH delay of this design. Protel's auto-router simply locks-up or
>does not initialize. The autorouter give no reason for the problem and
>Protel is either unwilling or unable to address the problem. Therefore,
I
>am under the impression that there is a major software problem with
>respect to the autorouter and BGA components. Has anyone else seen this
>problem? If any other user has had this problem or know of a fix,
PLEASE
>contact me ([EMAIL PROTECTED]). Thanks you for any feedback.
>
>Loop.
>Posted from Association web site by: Gerard Vanderloop
Yes the Protel 99/99SE autorouter has problems - but 3 months delay. I
could hand route a pretty large board in 3 months. And I know that
others
could double my throughput at least. With 2 BGAs and 10 layers to play
with there must be a *lot* of other stuff on it. 3 months to lay out a
board - OK you professional PCB designers what sort of size must we be
talking about here - 2 m x 2m? :-)
Not so sure about the etiquette of requesting replies by mail - in the
Usenet world this is considered bad form. This forum is a bidirectional
thing - "give a bit get a lot".
Others have discussed routing strategies for BGA in the past. I did try
to
have look through the archive
(http://groups.yahoo.com/group/protel-users-PEDA-Archive) but I could
not
find much there. and my own more extensive archive (going back years)
did
not show much of relevance. I do seem to recall someone saying they
were
having some success with autorouting BGAs. Was it Gordon Price?
Ian Wilson
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