RE>>qualification plan for BGA soldering... 1/3/97 We have been using IBM's CBGA for nearly 4 years for some high performance applications. Our computers are mainly mounted in VME chasses, some of which are in standard office environments, but some are in aggressive airborne environments. We didn't have the resources at the time for a true, rigorous qualification of them, but instead were able to utilize a considerable portion of IBM's reliability data as long as we used consistent assembly processes. The major component of this was to ensure that we have adequate solder paste volume for each site. We have done some testing on our own and found that the only real deficiency was exactly as George Franck mentioned: they failed at relatively high vibration levels. An inclusion of an epoxy underfill solved this problem. We now use 7 or 8 different BGAs (some plastic, some ceramic), and we've found this same vibration susceptibility (and fix) with all that we've tested. We have found BGA technology to be well-suited for our applications and extremely robust. At the risk of jinxing us, we haven't seen any field failures related to solder joint problems - and, yes, we would have seen them! The biggest problem that we've seen with this technology is with the array via reliability in the PWB. (Consider that these vias are generally on the small side, and boards with BGAs tend to have more layers.) We had a significant number of failures initially but have taken steps to minimize them. Greg Bartlett Mercury Computer Systems Chelmsford, MA [log in to unmask] -------------------------------------- Date: 1/3/97 10:35 AM To: Greg Bartlett From: George Franck Jr Obrien, I have not run a qualification program for BGA's. As such, I am only watching from the sidelines, however, I have gleaned the following information off the technet and other articles in our library. It is my opinion that BGAs are good for applications with temperature ranges of 30deg C and less, 50 deg C being the limit. Applications basically are room temperature / air conditioned applications. I think Compaq Computer is still the bigest user of BGA's. Another big consideration is vibration. Happy Holden of HP-Loveland, or Fort Collins CO, expressed frustrations with BGA's in (Inkjet?) printer applications in a posting last year. Too much vibration caused failure rates to exceed HP's targeted reliability. (I was so impressed that a consumer electronics firm did reliability studies, that I went out and bought an HP Ink Jet.) It has been my observation that most reliability studies of BGA's confine their use to very beniegn environments, and report excessive failures in other environments. There are many different configurations commonly refered to as BGA's which have different reliability levels. BGA package suppliers are not all the same. Variables, Variables, Variables. It seems to me that reliability studies usually bring bad news. Again, these are my observations from the side lines. Success stories may be suppressed as 'company sensitive' information. Good luck. I would be interested in following your progress. Finally, there is a JPL study in progress for NASA to determine the if BGA's can be used for NASA-type applications. Check this for an idea of how they set up their experiment: http://arioch.gsfc.nasa.gov/eee_links/vol_01/no_03/eee1-3h.html (I hope I typed it in correctly) -- George Franck Jr Raytheon E-Systems Falls Church Va. "The opinions expressed are those of the author, and are not necessarily those of the Raytheon Corporation." *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************