Bev, You are completely right. This product that I have been "baptized" into has been a 4 year terror. I am probably the 8th set of eyes to look at it. I have seemed to make the most progress but that doesn't mean a thing. All I do know is that the design is not good, the parts are obsolete and the board is already being produced in a new generation build, so basically I am stuck with what I have. Even though scrap is high on this board, they just want to pump them out till they fizzle out. So I am stuck with trying to find a reliable way to solder these BGA's when in 4 years they haven't been able to on this board. I know that the warping on the board is causing the issue in conjunction with the uneveness of the BGA package, neither of which can be changed. Ronald D. Peeler Jr., B.S. IE Process Engineer SWEMCO Moorestown, NJ 08057 Tel: (856).222.9900 ext. 31 Cel: (484).948.0779 Fax: (856).222.0700 [log in to unmask] -----Original Message----- From: Bev Christian [mailto:[log in to unmask]] Sent: Wednesday, April 25, 2007 4:58 PM To: [log in to unmask] Subject: Re: [TN] BGA Weights Ron, The problem right now is you see an effect and you do not know the cause. It could be that the board and/or component warps and you have opens. It could be that you have a head-in-pillow situation. It could be that you have internal component opens. It could be that you have cracked solder joints. You have to figure out which it is before you try to apply a remedy. Bev RIM -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Ron Peeler Sent: Wednesday, April 25, 2007 4:38 PM To: [log in to unmask] Subject: Re: [TN] BGA Weights Don't try me I just might ask you that... :) Ronald D. Peeler Jr., B.S. IE Process Engineer SWEMCO Moorestown, NJ 08057 Tel: (856).222.9900 ext. 31 Cel: (484).948.0779 Fax: (856).222.0700 [log in to unmask] -----Original Message----- From: Wayne Thayer [mailto:[log in to unmask]] Sent: Wednesday, April 25, 2007 4:35 PM To: [log in to unmask] Subject: Re: [TN] BGA Weights Hi Ron! I think most people solve this problem by making sure the board and BGA are planar during the process, and that the solder paste is thick enough to make up the difference. Then you have the "collapse" process working for you too. Weights can be used but are painful--last resort. They absorb heat, messing up the solder profile, and need to be fixtured so they don't fall off during reflow. Next you are likely to ask for a rule of thumb for the pressure supportable by the solder surface tension and the compression of the solder balls which ensues. I don't know that--I just try weights until it works. Wayne Thayer >>> [log in to unmask] 4/25/2007 4:23:12 pm >>> Hello TechNet I was wondering is there anything in the industry that is used to weigh BGA's down? We are having an issue @ our shop with BGA's not soldering effectively to one of our boards. Currently we have a board that is suppose to go through a boot process, however it has problems doing so. The issue is resolved when you press down in the middle of the BGA and fails again once the BGA is released. It doesn't help that our board warps easily as well. Is there anything, small gram weights or so that can weigh down a BGA without shorting it? Thanks Ronald D. Peeler Jr., B.S. 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