Subject: | |
From: | |
Reply To: | TechNet Mail Forum. |
Date: | Wed, 24 Sep 1997 09:27:00 -0700 |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
Technetters:
I have been having a "heated" debate with a co-worker on PCB warpage
and I need some practical "real-world" feedback:
The hypothetical scenario is as follows:
A multilayer PCB is constructed with prepreg layers of DIFFERENT
curing time/temperature characteristics. The resultant stack is
laminated in accordance with the requirements for the lesser material,
thus leaving one or more prepreg layers partially cured.
Questions:
1) Will this board warp during reflow and/or wave soldering? (Assume
no components are mounted, so component weight is not a factor in the
equation)
2) If so, will it continue to warp with multiple thermal cycles (e.g.
additional reflow cycles)? What forces are at work to cause the
warpage in the first place?
3) If the answer for #2 is YES, is the additional warpage with
successive thermal cycles predictable as a percentage of the original
warpage?
Thank you in advance for your assistance in "cooling" the argument.
Bill Fabry
Plantronics, Inc.
[log in to unmask]
##############################################################
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.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
##############################################################
|
|
|