There are copper peel strength tests/criteria documented in the IPC
specs and especially in IPC-TN-650, but I do not know just how effective
they are. 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Edwards
Sent: Tuesday, March 18, 2008 12:19 PM
To: [log in to unmask]
Subject: Re: [TN] Solder Mask Defined Pad BGA Reliability

Graham,

I'm getting in this a little late but this is my 2 cents...

We sometimes have problems with SMD pads because the PCBs we get seem to
have an organic or foreign material on them after they are processed...
This generates weaker bonds which fail at lower stresses...They can
literally pop off the PCB...

Do any of the PCB fabricators have a way of guaranteeing that SM
residues are 100% removed from the pad surfaces?

Paul

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kirk, Graham (GE
EntSol, Intelligent Platforms)
Sent: Tuesday, March 18, 2008 3:18 AM
To: [log in to unmask]
Subject: [TN] Solder Mask Defined Pad BGA Reliability

Hi All,







Can anybody tell me what the actual mechanism is that propagates cracks
in the device to ball joint on plastic BGA's (Leaded balls) with SMD
pads under thermal cycling?







Graham Kirk



Senior Technologist



GE Fanuc Intelligent Platforms Ltd




---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 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 email and any attachments thereto may contain private,
confidential, and privileged material for the sole use of the intended
recipient. Any review, copying, or distribution of this email (or any
attachments thereto) by others is strictly prohibited.
If you are not the intended recipient, please contact
[log in to unmask]
immediately and permanently delete the original and any copies of this
email and any attachments thereto. 

========================================================================
======


---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 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
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
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
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
-----------------------------------------------------