Tim,
        you have an even/balanced board stack-up as long as the laminate
materials are all the same (i.e. not some bizarre hybrid laminate stackup).
It would seem you are counting copper layers rather then laminate layers,
there is always one additional copper layer because you have copper on both
outer layers. I don't see any problem or issue with your stack-up, seems
good. However, your stackup would only give you approx. 54 mil total board
thickness with 1oz. Cu layers, was 0.063" a controlled target thickness, are
you using thicker plating on some layers? If you are using thicker/thinner
CU on some layers then this should be balanced across the stackup as well.

Brad Velander,
Lead PCB Designer,
Norsat International Inc.,
#300 - 4401 Still Creek Dr.,
Burnaby, B.C., V5C 6G9.
Tel. (604) 292-9089 direct
Fax (604) 292-9010
website www.norsat.com


> -----Original Message-----
> From: Tim Hutcheson [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, August 22, 2001 10:53 AM
> To: Protel EDA Forum
> Subject: [PEDA] Warping on small odd layer boards.
> 
> 
> 
> Has anyone any experience building small (4x7 inch) 7-layer 
> .063" boards?  I
> would like to have a certain stack up impedance that is best met with
> 4,9,9,9,9,4 for the 5-mil trace widths I am using but I know 
> from what I
> have read that warping can be a problem.  On the other hand, 
> a conventional
> an 8-layer board would thin the layers and upset the 
> impedance and a 6-layer
> board adds impedance calculation problems and more layout issues.
> 
> Do vendors even build odd layer boards?
> 
> regards,
> 
> Tim Hutcheson

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