Hi Jerry - processing a double sided BGA PWA design is no different than processing a double sided 0.4mm (16 mil pitch for the metrically impaired) QFP PWA design. You need to calculate your surface tension to component weight ratio to make sure that physics are in your favor. I have done some soldering trials with reasonable success without taking any special steps (pad design, footprint location, etc. ) other than conducting the normal assembly reflow profiling steps. I would be more concern with having the BGA's located to facilitate rework if necessary. Having the BGAs mirror each other on opposing assembly sides or having high profile components adjacent to a BGA (i.e. a high skyline) would be a problem for our rework scheme. Spending time on getting the reflow profile tuned has been the key for me. Good Luck. Dave Hillman Rockwell Collins [log in to unmask] Jerry Cupples <[log in to unmask]> on 06/23/98 05:15:22 PM Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to Jerry Cupples <[log in to unmask]> To: [log in to unmask] cc: (bcc: David D Hillman/CedarRapids/Collins/Rockwell) Subject: [TN] ASSY: BGA sanity check Hello, TechNet.... Soldering (inline convection furnace) BGA's on both sides of a board is beyond my own experience, but it seems to violate a principle (at least an imaginary one) related to the controlled collapse, or perhaps liquids under tension. For a board design using 3 commercial BGA packages (PBGA 256, eutectic balls on 1.27 mm pitch), am I obstinately blocking the path of progress by requesting that this package style be confined to only one surface of a new board design? If you are doing this today and it is a piece of cake, go ahead and brag; but I would prefer to hear that caution is well advised, i.e. tales of misery, shame and corporate disaster resulting from such mistakes. ;-) cheers, Jerry Cupples Interphase Corporation Dallas, TX USA http://www.iphase.com ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################