Thank you Wayne,
I'll probably have to do DSC to measure the Tg and delta Tg, but if the difference is subtle, then the company won't be able to "push" the supplier.
I hate situations like that, as there is no definitive answer and both sides are right in a sense.
Vladimir
SENTEC Testing Laboratory Inc.
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812
www.sentec.ca
-----Original Message-----
From: "Thayer, Wayne - IIW" <[log in to unmask]>
Sender: TechNet <[log in to unmask]>
Date: Thu, 29 Sep 2011 20:19:07
To: <[log in to unmask]>
Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
"Thayer, Wayne - IIW" <[log in to unmask]>
Subject: Re: [TN] Board question
Hi Vlad-
I think you can certainly conclude that the warping is due to poor temperature control on the cooldown cycle: One side is cooling faster than the other. So when you put the unwarped board in, it comes out warped. Put the warped board in upside down, comes out straight. Probably same effect no matter which side you start with. This is the magic of glass transition.
Why this lot? Subtle difference in prepreg lots may give a bit difference in glass transition temperature.
Fix by fixturing, getting higher glass transition temp materials, or fixing cooldown zone!
Wayne
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of vladimir Igoshev
Sent: Thursday, September 29, 2011 3:49 PM
To: [log in to unmask]
Subject: Re: [TN] Board question
Can it go back to normal after second re-flow?
I sectioned the boards at the same location and the bundles look similar.
Vladimir
SENTEC Testing Laboratory Inc.
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812
www.sentec.ca
-----Original Message-----
From: "Stadem, Richard D." <[log in to unmask]>
Date: Thu, 29 Sep 2011 14:44:51
To: TechNet E-Mail Forum<[log in to unmask]>; Vladimir Igoshev. PhD<[log in to unmask]>
Subject: RE: [TN] Board question
It could be the ORIENTATION of the PWB with respect to the direction of the glass bundles. If the boards were cut from the blank with the long dimension oriented with the strand orientation at one vendor and the short dimension with the other, the warpage can occur at one and not at the other.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev. PhD
Sent: Thursday, September 29, 2011 11:50 AM
To: [log in to unmask]
Subject: [TN] Board question
Hi TechNetters,
I have a question for board gurus, as I'm almost lost.
Here is a story. A panel of four simple 4 layers FR4 twists after
going through the first side re-flow and flatten out after the second
side is re-flowed. It does the same thing with and without the
components placed.
The panels are from new vendor and the old ones had never exhibited
the problem. What confused me is that both boards (from both of the
vendors) were built identically: dielectric layers and Cu
layers are look identical thickness- wise.
There are no signs of resin recession or delamination in
cross-sections which could have pointed out at incomplete curing.
Glass bundles look also identical.
What else it could be?
Any suggestions are deeply appreciated.
--
Best regards,
Vladimir Igoshev. PhD mailto:[log in to unmask]
SENTEC Testing Laboratory Inc.
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812
www.sentec.ca
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
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 MessageLabs Email Security System.
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 e-mail and any files transmitted with it may be proprietary and are intended solely for the use of the individual or entity to whom they are addressed. If you have received this e-mail in error please notify the sender.
Please note that any views or opinions presented in this e-mail are solely those of the author and do not necessarily represent those of ITT Corporation. The recipient should check this e-mail and any attachments for the presence of viruses. ITT accepts no liability for any damage caused by any virus transmitted by this e-mail.
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
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 MessageLabs Email Security System.
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
-----------------------------------------------------
|
