Janine - 

Are you resending your original post, or is the listserver messed up and
resending your original post instead of the responses to it? I now see 5
copies of it out there, but only one response ... from Earl Moon,

JaMi Smith

-----Original Message-----
From: Janine Badcock [mailto:[log in to unmask]] 
Sent: Tuesday, April 02, 2002 4:28 AM
To: [log in to unmask]
Subject: [TN] BGA/Highspeed Design Technologies

We are just about to embark on our first BGA/highspeed design.

Board specification : -

Double Side Surface Mount Board.
With 225 pin 1mm pitch BGA's on each side
Datalines @100Mhz and impedance matched to 50 ohms.
Powerplanes 3V3 and DGND (digital ground)
Military specific applications
Maximum Board Thickness 1.8mm

Could anyone with any experience of the above please comment on the
following : -

1.      Layer stack (blind & buried vias?)
2.      Technology (microvias?)
3.      Via size
4.      Track size
5.      Materials

We have been advised that for high speed digital designs that we should
limit the
number of vias through ground and powerplanes.

If you have any additional information/comments about the design you
feel would be
useful for us, we will be grateful.

In anticipation

Many Thanks



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