Erika,

I agree with Tim.  I would ask the board house for a 4-layer stackup
that is inexpensive and easy for them to fabricate.  Then I would run it
by the EE.  If the EE okays it, you can put that stackup in the fab
drawing.  

You might ask the EEs first if they want the inner layer close together.
Sometimes we want them close for extra capacitance between the inner
planes.  Other times it's better for them to be far apart so that outer
traces are close to the planes allowing narrow traces to have a
reasonable impedance.    

CJ

-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of
Sanchez-Benavides, Erika
Sent: Tuesday, May 30, 2006 3:42 PM
To: [log in to unmask]
Subject: [DC] Distance between external and internal layers 4Layer FR4

Hi!


What is the standard distance between External and internal layers
for 4-layer board, FR4?

Should I specify an specific distance in my notes?
 In any case, the key point is that whatever is specified now should not
change later.

How can I get this?

Thanks in advance for your help.

Erika

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