Baking at 105 C allows the moisture to ramp up just above boiling temp, allowing the moisture to be driven out safely over a period of time. The RATE at which the moisture is driven out is critical. For standard FR-4 PWBs, the bake duration required to get to the "safe" level of 20% of saturation is between 8 to 24 hours, depending on a number of factors such as number of layers, slash type, amount of copper, etc.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Garcia, Rigo (GSFC-300.0)[MANTECH SRS TECHNOLOGIES]
Sent: Thursday, November 17, 2011 10:28 AM
To: [log in to unmask]
Subject: [TN] Recommended Bakeout Temperature for Boards and Assemblies
Good day TechNetters!
I have been reading all sorts of materials regarding bakeout of boards and the consequences. Among some of the documents I've read is IPC-1601 - "Printed Board Handling and Storage Guidelines".
One of the main questions I still have is, if moisture contributes to delamination by the internal forces generated internally on the PCB when heating up the board at high temperatures due to the evaporation of the water, why would anybody recommend temperatures above 100 °C which is the boiling temp for water? For instance, baking at 125 °C would create the same effects we are trying to avoid, wouldn't it?
Does anybody know any good reading material to learn about this?
Thanks for the help!
Rigo Garcia
Sr. Quality Assurance Engineer
Workmanship Standards, Code 300
NASA, Goddard Space Flight Center
Greenbelt, MD 20771
Phone. (301) 286-6129
Fax. (301) 286-6576
______________________________________________________________________
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]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
______________________________________________________________________
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]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|