Chris,
boards are like bimetallics, if there is a difference in CTE somewhere, the material will bow one or the other way. Therefore, the board materials have to match each other. Done by balancing of copper tracks, direction of pattern and a lot of other tricky things. As this is daily work for many persons, I recommend you to speak with one such clever guy. Call Simon Hutter at 41-71-878 7782. I guess his company have made boards for you. / Ingemar



Friends:

I have a 6 layer board that warps.  The R&D group tells me its a
Manufacturing problem. I'm not so sure.

Details:
.062" Thick NEMA FR4
Stack: (Trace/Gnd/Trace/Trace/Power/Trace) w/1/2 oz copper clad.
R&D group tells me the layers are balanced from the center of the stack
out.

What should Manufacturing be doing to prevent these boards from
warping?  Or is the only solution a higher temperature
FR4 material that adds cost to the board.  Could it be a problem with
the board house. Please advise.

Regards, Chris

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
847-509-9700 ext.5365
##############################################################