Lots of the things you and others have said about Tan G
Richard,
Lots of the things you and others have said about Tan Geok's failures
may be correct but I think they are all speculations based on what we
think the images show. However, I'm not sure the quality of the cross
section is good enough to see the signature of the failure. My
suggestion to Tan Geok would be to have the lab re-polish and microetch
the cross section and take good quality color photomicrographs.
Regards,
George
George M. Wenger
Andrew Wireless Solutions
Senior Principal FMA / Reliability Engineer
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 [Office] (732) 309-8964 [Cell]
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Friday, January 16, 2009 10:48 AM
To: [log in to unmask]
Subject: Re: [TN] Possible cause on open
I expanded the images and I am sending them back to Steve for
re-posting. I can see a lot of flower-petal patterns, a lot of rod and
cone structures just above the IMC. It appears as if there are very
heavy gold intermetallics along the top of the IMC, and the gold
nucleated back towards the IMC from the solder ball. The IMC layer is
very thin.
The solder between the edge of the soldermask and the edge of the pad
causes the pad edge to look like they curled at the edges, but I think
you can see that it is just the crack curling downwards inside of the
solder. Full reflow obviously took place because the solder melted down
the sides of the pads and filled the space between the soldermask and
the curled edges of the pad. In the image taken near the center of the
pad, it is obvious the crack propogated through the solder in some
areas.
The crack along the entire length of the pad and down the sides
indicates severe stresses due to either the vibration forces or the CTE
from the temperature cycling, or both. The crack probably formed due to
the brittle nature of the IMF, what with having the worst possible
combination of ENIG, lead-free solder, and lateral stresses. There are
some voids with flux debris above the whole thing that tend to confuse
the issues going on.
Steve, I am sending my expanded image to you for posting separately.
Thanks.
Richard
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Igoshev, Vladimir
Sent: Thursday, January 15, 2009 8:42 PM
To: [log in to unmask]
Subject: Re: [TN] Possible cause on open
Thank you for sending me the image. Honestly, I don't quite understand
what I see. The finish doesn't look like ENIG and the cavity above
something that DOES NOT look like a typical intermetallic shouldn't be
there, not to mention a "hair-like" something (crack?????) above the
cavity.
It looks like a proper joint had never been formed. Can you ask the lab
to slightly etch the section?
Regards,
Vladimir
________________________________
From: Tan Geok Ang
To: Igoshev, Vladimir; [log in to unmask]
Sent: Thu Jan 15 20:09:33 2009
Subject: RE: [TN] Possible cause on open
About 1.05um
________________________________
From: Igoshev, Vladimir [mailto:[log in to unmask]]
Sent: Friday, 16 January 2009 9:01 AM
To: Tan Geok Ang; [log in to unmask]
Subject: Re: [TN] Possible cause on open
The info I'm asking about is at the bottom of the images you sent to
Steve. You should be able to read from the originals what it says (how
many microns)
Regards,
Vladimir
----- Original Message -----
From: Tan Geok Ang <[log in to unmask]>
To: TechNet E-Mail Forum <[log in to unmask]>; Igoshev, Vladimir
Sent: Thu Jan 15 19:53:13 2009
Subject: RE: [TN] Possible cause on open
The service lab has not come out much information at this time. Will
input you once I have the information. Thank you.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Igoshev, Vladimir
Sent: Thursday, 15 January 2009 10:50 PM
To: [log in to unmask]
Subject: Re: [TN] Possible cause on open
It looks like there could be something fishy in the intermetallic layer.
GA, can you tell me please what is the reading on the micron bars?
Regards,
Vladimir
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Thursday, January 15, 2009 8:05 AM
To: [log in to unmask]
Subject: Re: [TN] Possible cause on open
Mornin' Everbody!
Well, here in Tulsa, we're just like a lot of other people in the
country this morning, trying to stay warm. Right now we're sitting at
-10 C. with a wind chill of -15 C. It's supposed to be colder
tomorrow...
GA, I have your pictures posted now. They're at:
http://stevezeva.homestead.com/files/Fracture1.jpg
http://stevezeva.homestead.com/files/Fracture2.jpg
Hopefully someone can give you some ideas...
Steve
________________________________
From: Tan Geok Ang [mailto:[log in to unmask]]
Sent: Wednesday, January 14, 2009 7:27 PM
To: [log in to unmask]; Steve Gregory
Subject: Possible cause on open
Hi Steve,
Please help to download these pictures TechNet, thanks.
Hi All experts,
Testing (combine test of 16G at 85 oC) was performed on
evaluation boards with under-filled BGAs. Open issue (cracks) was
detected only at some corners of the BGA (35x35mm with 1156 balls) after
the test. Lead-free process and PCB with ENIG surface finish. Peak
temperature is 248 oC with a 65 sec above 217 oC.
FYI, the service lab has not come out a report.
What are the possible causes? (CET mismatches, Lead-free
alloy related, material, processes)
Thank you in advance.
Regards
GA Tan
---------------------------------------------------
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
-----------------------------------------------------
---------------------------------------------------
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
-----------------------------------------------------
No virus found in this incoming message.
Checked by AVG - http://www.avg.com
Version: 8.0.176 / Virus Database: 270.10.7/1894 - Release Date:
1/16/2009 6:52 AM
------------------------------------------------------------------------------------------------
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 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
-----------------------------------------------------
|
