Tony This is easy to see in the screen printer machine, just load the board and do the align without printing ( most of screen printers has this capabilities ) , go into the machine and see if all stencil apertures are aligned with the board pads, from there you have the final conclusion ... Jorge Santana -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of tony steinke Sent: Friday, March 29, 2002 12:49 PM To: [log in to unmask] Subject: [TN] solder paste registration Ladies and Gentlemen, We are having a major problem with an assembly house with registering the solder paste to surface mount features prior to pick and place. They are claiming that the boards are growing/shrinking some 15-20 mils. We have done extensive measuring on unpopulated boards in-house and cannot see more than 3-5 mils misregistration. The panel size is approximately 14.00 x 16.00 inches, 20-24 mil pitch, and 15 BGA's throughout the panel. Overall thickness .080. Is it possible that the mesh screen that they are using can expand/contract over time? has anyone heard of this experienced this situation before. Any information would be greatly appreciated. Thanks Tony Steinke AIT-Atlanta