Hi Tom:

Did you autoroute this board?

tr :)


-----Original Message-----
From: Tom Reineking [mailto:[EMAIL PROTECTED]
Sent: Monday, July 26, 2004 1:48 PM
To: Protel EDA Forum
Subject: Re: [PEDA] first BGA layout


Ralph,

This is just an aside and not an explanation to your problem.  I laid 
out a board with 3 BGAs are 0.75 mm and one 256 pin BGA at 1 mm 
spacing.  Using .004" tracks with .004" spacing I was able to route the 
whole board on two signal layers with two power layers and no special 
vias, meaning all were through hole, .018" pad .010" hole.  It did take 
some time and careful planing but at a huge PCB cost savings.  Any time 
you go over 4 layers and start using fancy vias the cost accelerates 
geometrically.  I your case that may not be an issue but in mine I had 
no choice.  Don't forget to use gold flash for the BGAs (for the whole 
board is easier) to reduce manufacturing problems with soldering BGAs.

Cheers,
Tom

Ralph Effinger wrote:

> I am haveing trouble laying put an 8 layer board. I have a schematic,
> board with chips, resistor,caps and one 256 bga. The bga has a 1mm
> pitch. I have setup the layer stack mang. and the desing rules the best
> I know how,{this is my first bga}. I layed out the board using blind or
> buried vias. I am using protell 99se. after auto routing the board, the
> vias all go from the top layer to the bottom not useing any blind or
> buried vias. I,ve looked at the tutorials and book, and can find 
> nothing to help me.       thank you!
>
>
>
>
>
>




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