Hi gang! Just one additional comment to add to Steve's good information. The wetting characteristics of glass are not the same as most BGA laminate materials so after using dummy glass methodology that Steve described, it is always a good idea to run a few samples with the specific BGA to confirm that you are getting the flow distribution that you expect. Dave Hillman Rockwell Collins [log in to unmask] "Creswick, Steven" <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 11/01/2007 05:07 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to "Creswick, Steven" <[log in to unmask]> To [log in to unmask] cc Subject Re: [TN] verifying BGA underfill coverage Joe, Acoustic microscopy is about the best method I can think of, but you still need to be an intelligent consumer. The biggies like Sonix and Sonoscan both make good equipment. The transducers and software really make the difference, and the software is improving on a continuing basis. It is also possible to make 'dummy' flip chips if you have access to metal deposition and patterning of glass. Buying and placing solder spheres is the only other task that you would need for that approach. It REALLY helps to understand the under-fill's flow characteristics when you can actually see it as it happens. I learned a great deal from this approach using an old Camelot 1414. Ever considered a flux under-fill [or no-flow under-fill]? Steve -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Macko Sent: Wednesday, October 31, 2007 7:34 PM To: [log in to unmask] Subject: [TN] verifying BGA underfill coverage Fellow Techs We purchased a GPD automated epoxy dispenser and I want to proof out the new automated underfill application process on BGAs. We use a wickable Loctite underfill that requires an elevated temperature to flow properly under BGAs, etc.. Currently we successfully underfill by hand and want to switch to an automated process using the GPD. I want to verify the underfill coverage under BGAs using a non-destructive test method. The only non-destructive method I am aware of is acoustic imaging using an instrument such as Sonoscan, which I believe will show voids in the underfill material. I do not know how industry non-destructively verifies underfill coverage. I plan on physically removing some BGAs on scrap boards to verify coverage but do not want to do this on good boards for obvious reasons. Question - What is the commonly accepted non-destructive method for verifying BGA underfill coverage? Look forward to your comment. thanks Best Regards, - Joe --------------------------------------------------- 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 ----------------------------------------------------- THE INFORMATION CONTAINED IN THIS E-MAIL MESSAGE AND ANY ATTACHMENTS SENT FROM GENTEX CORPORATION IS GENTEX CONFIDENTIAL INFORMATION INTENDED ONLY FOR THE PERSONAL USE OF THE INDIVIDUAL OR ENTITY NAMED ABOVE. 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