George's msg below reminded me that he provided me a copy of Ingemar Hernefjord's paper "Electroless Nickel/Immersion Gold PWB's vs SBGA's".
Thanks to Ingemar and George for making this available.
The file is just a bit over 22 MB and can be downloaded from either of these links. File size is about the same but if one doesn't work, try the other
http://files.ipc.org/69_15961ue.pdf
http://files.ipc.org/69_15961ue.zip
Scope
Since last year electrical opens were found on boards with Xilinx superBGA560. The boards are equipped with minimum one and maximum five such large BGAs together with all sorts of other SMT components, even smaller BGAs.
Significant for the failures is that the open is sensitive for external pressure such as just pressing your finger on top of the package can either cause abrupts or reestablish the electrical contact.
This report may seem sweeping and overworked and not coming to the point. It's the meaning. More kind of a discussion which gives many more insight in the problematic things. And finally, there was no time for editing and professional design of the report.
Searching words
BGA, sBGA, superBGA, ENIG, Electroless Nickel, Immersion Gold,
Intermetallics, IMC, Nickel/Tin,
Content
1. Presentation of the hardware under discussion
2. First acquaintance with a trouble maker
3. SuperBGA's drop off shocked PWB
4. Comparison with a MARK-PWB from 1998
5. Mini about Tin/Nickel and IMCs on tinned surfaces
6. Simple wetting test on actual ENIG board
7. Investigation to find possible Hyperactive Gold Corrosion
8. Parallel investigation by IVF and Chalmers University
9. What the Ericsson specialists had to add
10. Remarkable case, for learning
11. Other sources
12. Good articles and links
13. Is the sBGA itself the real problem?
14. Metallurgical investigation of some soldered Xilinx sBGAs
15. About dewetting
16. Further destructive test in order to study the cracks and the separation
between bga ball and pwb
17. US comments on chapter 16
18. SBGAs on other Ericsson boards
19. Investigations by Xilinx in San Jose
20. About our own soldering process
21. Simple experiments with Vapour Phase Soldering
22. A look on a sBGA processor from Intel
23. Proposed actions
24. Summary
25. References
Innehåll Avdelning II, BGA-lödningsproblem MCM-linan Borås
23. Genomgång av rapport till SP/TC: SP/AU-1999:018, sid 63
24. Första fallet: ROP 101 1417/1 för MXVB, MWNT, MXV4, MXV9
25. Lödprocessen I Bs
Jack Crawford, IOM
IPC Director Certification and Assembly Technology
[log in to unmask]
847-597-2893
FAX 847-615-5693
3000 Lakeside Drive, Suite 309 S
Bannockburn, IL, 60015
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M.
Sent: Wednesday, June 08, 2005 9:16 AM
To: [log in to unmask]
Subject: Re: [TN] Solderability issues with ENIG finish
Michel,
I'll wait to comment until after I look at the picture once it is posted on Steve's web page but I couldn't tell from your description if there was a component on the pad and if so was it removed or was the pad that was examined a non-populated pad?
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 Arbour, Michel
Sent: Wednesday, June 08, 2005 9:48 AM
To: [log in to unmask]
Subject: [TN] Solderability issues with ENIG finish
> Hi ,
> We've been having some solderability problems with one of our
> supplier. A populated PCB was sent for elementary analysis and we got
> the results back from the lab.
> Before going further in the corrective action process i would like to
> know if some of you agree and support the conclusions of the report
> based on the following data.
>
> - The board sent to analysis was populated , one half of a smt pad
> did not wet with solder the other half wetted properly
> - The problem was noticeable on approx. 2% of the lot of PCB. 2-3 pads
> per board
> - The pad could not be soldered using an iron pen
> - Solder paste is standard Sn63, Pb37
>
> Two area on the pad were analyzed, one that was wetted , the other was
> not.
> Concentrations of element found were the following
> - On the wetted area of the pad ALIAS : "AREA B"
> 5.40% C
> 2.04% N
> 0.81% O
> 45.32% Sn
> 2.45% Ni
> 3.67% Cu
> 40.31% Pb
>
> On the unsolderable area of the pad ALIAS "AREA A"
> 6.08% C
> 9.08% P
> 9.55% Sn
> 66.62% Ni
> 3.47% Cu
> 5.20% Au
>
> The conclusion of the report states :
> Area A is a fracture surface at the intermetallic boundary while Area
> B is a fracture surface at or near the bulk solder. No mud cracking
> is seen at Area A which indicates that black nickel was most likely
> not present. The fact that there is a fairly large gold peak at area
> A indicates that there may not have been sufficient time to adequately
> form the solder joint as the gold may not have had time to diffuse into the bulk solder.
>
> I can post a picture of the pad if you can point me to a location
>
>
> Michel Arbour
> Kontron Canada Inc.
>
---------------------------------------------------
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
-----------------------------------------------------
---------------------------------------------------
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
-----------------------------------------------------
|
