I am troubled by the percent gold. It seems pretty high, like there wasn't much time for diffusion. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory Sent: Wednesday, February 24, 2010 5:23 PM To: [log in to unmask] Subject: Re: [TN] Hackneyed? Hi Inge! Well, we are getting ready to get hammered by another winter storm. Starts tonight sometime after midnight and will last until Friday. They're forecasting anywhere from 12-16" of snow. I'm having a hard time getting used to the Pennsylvania winters... Anyways, I have your pictures posted. I'll paste the links into your email below as you are explaining the pictures. That way everyone can follow along easier. Steve -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Sent: Wednesday, February 24, 2010 2:54 PM To: [log in to unmask] Subject: [TN] Hackneyed? Hi Folks, am asking you to sacrifice a minute on a topic that may make you sick, as much as it has been discussed. Have a look at the SEM images that (hopefully) will be beamed by our most honorable guy, Dr Gregory. By order: 1. Pic 38 BGA ball after the preying off the 560 ball BGA from the board. SEI mode. http://stevezeva.homestead.com/files/XILINX_Daniel_38.jpg 2. pic 39, same at x 5,000 http://stevezeva.homestead.com/files/XILINX_Daniel_39.jpg 3. pic 40,samet at x 10,000 http://stevezeva.homestead.com/files/XILINX_Daniel_40.jpg 4.pic, 41 same at x 20,000 These four show the face of the pulled-off balls. The package/board was sectioned into halv by half inch pieces with a thin blade diamond saw and then each BGA section was separated from the board by means of a steel. http://stevezeva.homestead.com/files/XILINX_Daniel_41.jpg After SEM 1-4 I made EDS, which can be seen below. 5. http://stevezeva.homestead.com/files/XILINX_Backlund_Ball_2.doc As you can see, there is nearly no Lead (!), a high w/% Nickel, a little Tin and lots of Phosphorous. Clearly, the separation has been in a Now, continue with having a look at the board pads after the preying-off. 6. pic 44, Board pad at low magnification and SEI mode. http://stevezeva.homestead.com/files/XILINX_Daniel_44.jpg 7.pic 46, same at x 5,000 http://stevezeva.homestead.com/files/XILINX_Daniel_46.jpg 8.pic 48, same at x 10,000 http://stevezeva.homestead.com/files/XILINX_Daniel_48.jpg 9. pic 50, same at x 20,000 http://stevezeva.homestead.com/files/XILINX_Daniel_50.jpg 10. pic 51, same but with BS mode http://stevezeva.homestead.com/files/XILINX_Daniel_51.jpg 11. XILINX_backlund_pad_1.doc http://stevezeva.homestead.com/files/XILINX_Backlund_Pad_1.doc As you can see here, there is more Lead, a high w/% Nickell, much more Tin and still lots of Phosphorous. Discussion: Obviously, real and reliable solder joints are only in the circumperipheric of the whole (best understood with pic 10). How strong the adhesion was in the main part of the joint, we don't know. From the function (final) electrical testing, we have experienced several cases with disturbed signals. Many a times, we have had to remove the BGA and supersede with a fresh one. The test engineer told me, that by slightly add pressure to the BGA, he may get the signal through again. He thinks we have an issue with the uvias, others think there is a problem with the BGAs, myself I'm committed to my theory that this has to do with the rotten interface between the Tin/Lead and the ENIG pads. Question: Is anyone familiar with the said? What is your opinion about the demonstrated solder joints? Can yoy get cracks and electrical misfunction, despite that hundreds of balls are holding the BGA close to the board in a 'iron grip' ? Wayne? Steve? Dave? George W? Vlad? Thanks in advance. You'll have to wait for Steve to fix the exhibition. /Inge ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. 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For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- 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 -----------------------------------------------------