Phil,

This is a highly debated topic.  There are so many factors to consider there is no certainty in baking but we believe it does help reduce the risks.  We have had instances where we had delamination without baking and little to none after.

Some EMS's use the 125C for 24 hours but I promote 125C for 4-6 hours.  

I have my EMS consider the PWB as a MSL 3 for exposure.  May be overkill but it sets limits and there should be reason they cannot repair the PWB within the 168 hours.

Good luck and you will just have to set your limits and give it a try as there is not hard fast rule.

 
RUSSELL NOWLAND
ALCATEL-LUCENT        
REPAIR STRATEGY & SUPPLIER MANAGEMENT
14000 Quail Spring Parkway, Suite 100
Oklahoma City, OK 73134
T: +1 405 302 1660
F: +1 405 302 1622
M: +1 405 203 0034
[log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting
Sent: Wednesday, August 15, 2012 7:40 AM
To: [log in to unmask]
Subject: [TN] bare board pre-bake parameters



Good morning all,



We have recently had some boards delaminate and are considering pre-baking as a possible solution.  I need to know some "rules of thumb" for pre-bake time and temperature, suggested atmosphere (dry nitrogen?), allowable time between pre-bake and soldering.



At the moment I only have minimal information on the boards so I don't know their physical size, number of layers or if they are SMT or PTH.



I realize it could be a bad batch and the problem may only be with one group of boards as this is not a common problem with boards form many of our fab houses or CMs.



Thanks in advance,



Phil Nutting

Design for Manufacturing Engineer

Kaiser Systems, Inc.

126 Sohier Road

Beverly, MA 01915

Phone: 978-922-9300 x1310

Fax: 978-922-8374

e-mail: [log in to unmask]<mailto:[log in to unmask]>

www.kaisersystems.com<http://www.kaisersystems.com>

www.linkedin.com/in/philnutting<http://www.linkedin.com/in/philnutting>





________________________________

Note: All the information contained in this e-mail and its attachments is proprietary to Kaiser Systems, Inc. and it may not be reproduced without the prior written permission of sender. If you have received this email in error, please immediately return it to sender and delete the copy you received.





______________________________________________________________________

This email has been scanned by the Symantec Email Security.cloud service.

For more information please contact helpdesk at x2960 or [log in to unmask]

______________________________________________________________________

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________