> Top  (1/2 oz+1/2 oz) = cu foil
> Core 2-3: Inner1--gnd (1 oz)  inner2--signal 1 (1/2 oz)
> Core 4-5: inner3- pwr (1 oz)  inner4- gnd (1 oz)
> Core 6-7: inner5- signal 2 (1/2 oz) inner6- pwr (1 oz)
> Core 8-9: inner7- signal 3 (1/2 oz) inner8- gnd (1 oz)
> Bottom (1/2 oz+1/2 oz) = cu foil

Hi,
Unsymmetrical builds could cause warp and twist, but Unbalanced copper
distribution could also cause warp and twist.
For your design, I would be more concerned about the mixed copper ounce.
One difficulty for the FAB Assembly is to ensure the core 2-3, core 6-7 and
core 8-9 are punched on the proper side.
I would suggest if possible to avoid mixed copper ounce on the same core,
use 1 oz on all layers, and adapt line width and spacing accordingly.
Ex: Core 4-5 inner3- pwr (1 oz)  inner4- gnd (1 oz) has no risk to put the
core up side down.
(Take note the cores look all the same on FAB assembly.  It is difficult to
recognize which side is .5 oz and which side is 1 oz. )

One way to avoid mixed copper is to use Core construction.
But for your example, we still have mixed copper weight and the copper
thickness not balanced .

> Core 1-2: Layer 1 (1/2 oz)   Inner1--gnd (1 oz)
> Core 3-4: inner2--signal 1 (1/2 oz)  inner3- pwr (1 oz)
> Core 5-6: inner4- gnd (1 oz)  inner5- signal 2 (1/2 oz)
> Core 7-8: inner6- pwr (1 oz) inner7- signal 3 (1/2 oz)
> Core 9-10: inner8- gnd (1 oz) Layer 10


I agree with Charles and Mario, consult your board manufacturer and get
their recommendations.

Best regards,

Simon Dubreuil


----- Original Message -----
From: "ert ert" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, August 29, 2006 12:02 PM
Subject: [DC] symmentric and asymmentric layer stack up


> Hi All,
>
> I got a 10layer stackup as below,
>
> Top  (1/2 oz+1/2 oz)
> Inner1--gnd (1 oz)
> inner2--signal 1 (1/2 oz)
> inner3- pwr (1 oz)
> inner4- gnd (1 oz)
> inner5- signal 2 (1/2 oz)
> inner6- pwr (1 oz)
> inner7- signal 3 (1/2 oz)
> inner8- gnd (1 oz)
> Bottom (1/2 oz+1/2 oz)
>
> if I divide this into two halves and see the prepreg tickness, core
thickness both are equal. But if I look at the copper thickness the
thickness is not balanced on either halves (4.5 oz on upper half and 4 oz on
lower half). what issues this could cause in FAB and Assembly?
>
> Can I mark this stackup as asymmentric?
>
> Looking for your suggestions.
>
> Thanks,
> Nagaraj.
>
>
>
>
>
>
> ---------------------------------
>  Here's a new way to find what you're looking for - Yahoo! Answers
>
> --------------------------------------------------------------------------
-------
> DesignerCouncil Mail List provided as a free service by IPC using LISTSERV
1.8d
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
> To temporarily stop/(restart) delivery of DesignerCouncil send: SET
DesignerCouncil NOMAIL/(MAIL)
> Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
> --------------------------------------------------------------------------
-------
>  Send FREE SMS to your friend's mobile from Yahoo! Messenger Version 8.
Get it NOW

---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL)
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
---------------------------------------------------------------------------------