FreeLists / si-list / [SI-LIST] Re: BGA Fan Out

["Dr. Edward P. Sayre" <esayre@xxxxxxxx>]

Fred:

Yes and the stack-up is probably a poor design choice. The split planes 
under the signals are generally SI and EMI problematic, but cheaper than 6 
layer fabrication.

ed
=========
At 09:17 AM 11/14/2005 -0800, Fred Townsend wrote:
>I have a client that is proposing the following for his BGA fan out.
>
>BGA = 17 x 17 x 1mm with 0.6mm pads
>
>power is applied to the inside 9x9 grid leaving 4 rows, each side, on
>the outside for signals.
>
>4 layer stackup = sig/gnd/3 voltage split plane/sig with 4 mil sig to
>plane spacing
>
>vias are limited to a 10 mil drill size
>
>min trace to trace = 4/4/4 mils
>
>has anyone ever heard of doing such a thing?
>
>
>Fred Townsend
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