Woah !!!!!!!
Stop the presses !!!!!!!
Sounds like you might possibly need to control that stackup, possibly for
something like controlled impedance traces, which will vary drastically from
one build to another, unless you really define the stackup yourself . . .
If you truely have a "simple" PCB with none of these types of structures or
issues, then you really can just hand it to the board house and let them
build it as they please, and it won't make a difference.
But if you have any signals above 10 - 20 mHz, you possibly will see a
difference from one build to the next, if you just allow the board house to
do what fits the material that they have on hand.
It may be that you will not have any problems, but it is always a good idea
to have a follow-on order for additional boards, built with the same
materials and stackup as the first order.
The first thing you really need to do is figure out what, if any, special or
critical issues are involved with the circuit you are building, and then
what you need to do to go about a proper layout and stackup in the first
instance, and then, what, if anything, ill need to be done to insure that
future builds of the same boards are within the parameters dictated by these
speecial or critical issues.
JaMi
----- Original Message -----
From: "Robert Vanech" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, May 30, 2006 3:44 PM
Subject: Re: [DC] Distance between external and internal layers 4Layer FR4
Erika...
There is no "standard distance", Maybe a minimum based on where
it is used,
thickness requirements. connector constraints, voltage requirements,
impedance
concerns,etc. Talk to the box man and see what he/she has designed into
the final board
thickness. Then talk to the fabricator to see if there are any concerns.
4- layers is not
cutting- edge technology. When you finalize the thickness, it should be on
the master
fabrication drawing and should remain the same unless there is a technical
requirement
change. Hope that helps.
Regards,
Bob Vanech
BVAN Enterprise
----- Original Message -----
From: Sanchez-Benavides, Erika
To: [log in to unmask]
Sent: Tuesday, May 30, 2006 4:41 PM
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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