Just thought I followed up on the fallout of OMPAC style BGAs after underfill. All the packages are from one date code- 47th week of 2003. Most of the verfied failures were traced to open solder joints- they seem to be in no particular area of the parts- for example, the open pins under the BGA were P16, J12, N7, M8. They can press on the vias under the open joints and get electrical continiuty but don't know where in the solder joint the cracks are occuring. I am having acoustic microscopy being done on the parts right now but we normally do a underfill on a BGA mounted on a glass slide and all the samples do not show any obvious defects. Is there a way of determining the CTE in x,y and z axis of an soldered and underfilled part? As an experiment we did ICT test on non underfilled parts and the particular failure was at pin M8. I examined the periperal joints and Steve graciously posted them - they are http://stevezeva.homestead.com/sideNearC51a.JPG http://stevezeva.homestead.com/sideNearC51b.JPG To me the solder joints to the PCB look well wetted but I'm more used to a more squashed looking ball - the profile of the solderball to the package seems to have a more pronounced curvature. Would like some inputs from the experts - maybe I'm reading more into this. The profile indicates that the temperature under the center BGA joints are 214.5 C and a time above liquidus of 84 sec and the edge of the BGA is 216.4 C and a TAL of 86 seconds. Will also microsection failed joints after acoustic microscopy and plan to do SEM/EDS at the ball to package interface and all the cracks. Would black pad on the nickel termination on the BGA package contribute to a failure at this interface? Thanks Tom --------------------------------------------------- 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 -----------------------------------------------------