Inge, That was an interesting comment. Any idea on the maximum allows load on a single (say .5mm) BGA ball in a cycled environment. I have never seen this for soldered connection but I would expect it to be somewhere. Can anyone suggest some good reading? Bob Kondner -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Sent: Monday, November 30, 2009 4:15 PM To: [log in to unmask] Subject: Re: [TN] BGAs & Conformal Coating Doug, how can that be possible? When temperature rises, the coating ought to soften and should expand even horisontally, and when at lower temperatures, the coating should crimp. The only way I can see is if you have the situation of a closed in liquid, which one cannot be compressed. BGAs use to be very hard to rip from the board. I measured some 350 kg force necessary to pull off a very large BGA. Inge ----- Original Message ----- From: "Douglas Pauls" <[log in to unmask]> To: <[log in to unmask]> Sent: Monday, November 30, 2009 2:29 PM Subject: Re: [TN] BGAs & Conformal Coating Good morning Juan, I suspect that Xilinx wants you do do a thermal cycle study on solder joint reliability when conformal coating gets under the BGA. The stresses brought about by a mismatches in the coefficient of thermal expansion (CTE) can rip a BGA off the board and can severely deform the balls. Hillman and I did such a study here a few years ago. I can share a few pictures of what happens, if Steve Gregory would be kind enough to forward his present e-mail address for the photos. Not sure I have the right one. Doug Pauls "Juan T. Marugán" <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 11/26/2009 11:53 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to "Juan T. Marugán" <[log in to unmask]> To [log in to unmask] cc Subject [TN] BGAs & Conformal Coating Hi, I've read in a Xilinx guide that: "Xilinx has no experience or reliability data on flip-chip BGA packages on board after exposure to conformal coating. It is recommended that the end-user should characterize the board level reliability performance of Xilinx packages before production use." Does anybody know any infomation or study related with this topic? Thank you. Juan T. Marugán Indra Sistemas SA Espańa --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------