Dave- Thanks for your interest. My "wrinkles" are irregular. The "wrinkles" do not appear to be mechanically made. However, the balls were probed by the BGA supplier (different company than the BGA packager) during test at temperature (95C). These probe (prong) marks are evident on the sides of the balls, at the 4 quadrants. I don't believe they are causing any trouble. I am sending samples of the wrinkled balls to Mr. Ramsey, to see what he thinks of the metallurgy. Larry Jindra Mfg Engr Group Lead TRW Radio Systems [log in to unmask] w) 858-592-3424 f) 858-592-3940 -----Original Message----- From: [log in to unmask] [mailto:[log in to unmask]] Sent: Monday, April 01, 2002 9:07 AM To: [log in to unmask]; Jindra, Larry Subject: Re: [TN] Solder Ball Wrinkles Hi Larry. Is it possible that the "wrinkles" are not a reflection of solderball metallurgical microstructure but witness marks from test probing of the BGA by the component fabricator? Dave Hillman Rockwell Collins [log in to unmask] "Jindra, Larry" <[log in to unmask]>@ipc.org> on 03/29/2002 04:19:24 PM Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to "Jindra, Larry" <[log in to unmask]> Sent by: TechNet <[log in to unmask]> To: [log in to unmask] cc: Subject: Re: [TN] Solder Ball Wrinkles True, I was talking about appearance of the BGAs prior to mounting. We just did a blind installation test with the same packages from an earlier lot that did not exhibit "wrinkles." The result show a significantly greater voiding joints from the "wrinkled" BGAs, given the same paste, place and reflow processing parameters. Given that the same things that cause voiding can cause shorting, we have a process problem that appears to be caused by a supplier process. The packaging vendor claims the bad balls saw a normal process. I need to tell them we suspect they are ..... Larry Jindra Mfg Engr Group Lead TRW Radio Systems [log in to unmask] w) 858-592-3424 f) 858-592-3940 -----Original Message----- From: Guy Ramsey [mailto:[log in to unmask]] Sent: Friday, March 29, 2002 1:13 PM To: TechNet E-Mail Forum.; Jindra, Larry Subject: RE: [TN] Solder Ball Wrinkles As I read your message, we are not talking about BGAs that were mounted on boards. These are the packages before they were installed? It this true? Yes, I would be worried. Sound like something was wrong in the solder ball attach process. I am not very familiar with commercial methods. Reballing processes that produce wrinkled balls can be caused by excessive heat and excessive convection. > -----Original Message----- > From: TechNet [mailto:[log in to unmask]]On Behalf Of Jindra, Larry > Sent: Friday, March 29, 2002 12:59 PM > To: [log in to unmask] > Subject: [TN] Solder Ball Wrinkles > > > We have a lot of BGA packages from a custom package house with a > "wrinkled" appearance to the ball surface, most pronounced on top > of the ball, where they will interface with the PCB. These > packages are prone to shorting. > > Does anyone out there have an idea of what might cause that > "wrinkled" appearance, and why it might make the package > succeptible to shorting? > > > Larry Jindra > Mfg Engr Group Lead > TRW Radio Systems > [log in to unmask] > w) 858-592-3424 > f) 858-592-3940 > > ------------------------------------------------------------------ > --------------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > 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 delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search previous postings at: www.ipc.org > On-Line Resources & > Databases > E-mail Archives > Please visit IPC web site http://www.ipc.org/html/forum.htm for additional > information, or contact Keach Sasamori at [log in to unmask] or > 847-509-9700 ext.5315 > ------------------------------------------------------------------ > --------------- > --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------