> Hi, > > I'm just wondering if someone could answer this silly question...we have > on a board some BGA and other discretes components, when we look at the > X-Ray picture we see that we have void (flux entrapment), We look at our > BGAs and there are no trace of void before we pass it to the oven. Our > finnish is a Tin Lead the surface is not flat( HASL), we check our profile > and everything is perfect. Could our void could came from the finnish? like > this is not a flat surface could we find a void in the pad?? I know this > sound silly but I really don't see where those voids could came of. > > We didn't pass a empty board on the X-ray. > > > Thanks You > > Yannick Brisson Yannick I have awaited other responses, in case I was missing something. However, I suspect that you "problem" is related to reflow characteristics. Using conventional convection reflow, in order to ensure a suitable temperature profile is achieved on the BGA balls on the "interior" bumps, you have to "over-cook" the outside bumps. Such "over-cooking" might cause the problem you mention? The easiest way to overcome this problem is to use vapour phase - or "Condensation Soldering" to give it its modern term. The benefit being that you achieve a uniform temperature over all surfaces and in this way, control the over-temperature to a maximum of 5DegC over eutectic / melting. Can I provide more on the equipment? Just ask - but off-line please! -- Regards, Graham Naisbitt [log in to unmask] Mobile: +44 (0)79 6858 2121 Concoat Limited - Engineering Electronics Reliability NEW TechShot 05 now available please email us for your copy NEW NEW SoldaPro Wizard please email us for your copy NEW Web: www.concoat.co.uk AND www.concoatsystems.com Sales: Millfield House, Fleet Road Fleet, Hampshire GU51 3QF UK Phone: +44 (0)1252 813706 Fax: +44 (0)1252 813709 Manufacturing and Head Office: Alasan House, Albany Park Camberley, Surrey GU16 7PH UK Phone: +44 (0)1276 691100 Fax: +44 (0)1276 691227 --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------