Ioan,
Is your reflow profile a "Ramp to Spike" or a "Ramp to Soak to Spike"?
Regards,
George
George M. Wenger
Reliability / FMA Engineer
Base Station and Subsystems Group
Andrew Corporation, 40 Technology Drive, Warren, NJ 07059 (908) 546-4531 [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Tempea, Ioan
Sent: Thursday, August 25, 2005 10:19 AM
To: [log in to unmask]
Subject: [TN] Blistering of PCB at lead-free temperatures
Hi Technos,
wanted to start a pilot run, but the first PCB that we soldered ended up full of blisters when it came out of the oven. It is a 6 layers, full ground and power planes, about 6"x7", not a high density one, pretty light stuff on it, the toughest part is a transformer which needs a little more heating. The profile peaks at 250C on the PCB itself and the PCB is made out of FR4, Tg 170.
I said to myself that it must be humidity, so I baked 1 board, 8H @ 125C, and passed it through the reflow again. Same blistering, almost to the same extent. Then I took a totally different PCB that was hanging around on my desk for about 3 months, reflowed it at 250C and got just a tiny blister, probably due to humidity this time.
The questions I have are:
is 250C too much for a properly manufactured PCB?
If it's not the humidity what else could it be?
Any other test that I could do to get a better idea of the root cause?
Thanks,
Ioan
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
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
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
-----------------------------------------------------
------------------------------------------------------------------------------------------------
This message is for the designated recipient only and may
contain privileged, proprietary, or otherwise private information.
If you have received it in error, please notify the sender
immediately and delete the original. Any unauthorized use of
this email is prohibited.
------------------------------------------------------------------------------------------------
[mf2]
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
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
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
-----------------------------------------------------
|
