[PEDA] First BGA design with blind-buried vias.

[Brian Guralnick]

Richard, you basically hit the strategy I was working toward.

I guess my question would bettee be how to configure the signal layer pairs 
in 99se & any other size/optimal settings regrading blind/buried vias.

____________
Brian G.



----- Original Message ----- 
From: "Richard Sumner" <rls at rsumner.com>
To: "Protel EDA Discussion List" <PEDA at techservinc.com>
Sent: Wednesday, June 21, 2006 5:08 PM
Subject: Re: [PEDA] First BGA design with blind-buried vias.


> Brian,
>
> I'm currently debugging a 6 layer board with a 676 pin bga. I
> actually needed only 316 of the i/o pins, and I simply avoided the
> deep rows of the bga. With only 1 trace between bga pads, I can get
> the first two rows (counting from the outside in) on the top layer,
> and using thru vias I can get the next two rows (equivalent, you have
> to avoid blocking the planes with adjacent clearance around the vias)
> on the bottom (or any other layer). This is a low volume product, not
> very (parts) cost sensitive, so I can justify the larger package
> (It's actually a trade off with a more expensive board). It was my
> first board with ad2004, and I did make use of the fpga pin swapping
> (much easier than with 99se, but still not simple)
>
> Richard
>
>
> At 04:14 PM 6/21/2006, you wrote:
>>Ok, I'm still using P99SE.
>>
>>     I need to upgrade an existing project with the main IC being a 240 
>> QFP,
>>going to an Altera 484 pin, 1mm fineline BGA, however, there are some 
>>parts
>>under the chip.
>>
>>     My PCB is only 6 layers.  I've never done blind/buried vias before in
>>protel.  How should I configure protel to handle the blind-buried vias 
>>under
>>the BGA pads.  Am I attempting something that shouldn't be done?  Can some
>>BGA pads just be pads with no holes at all without upsetting the mounting?
>>Is there any good reason to switch to microvias?
>>
>>
>>____________
>>Brian G.
>>
>>
>>
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