This sounds almost like the mesh that holds the stencil in the frame is becoming weak and stretched allowing for extensive movement of the stencil during the printing operation. IMHO. Barry. -----Original Message----- From: Edward S. Wheeler [mailto:[log in to unmask]] Sent: Friday, March 29, 2002 9:48 AM To: [log in to unmask] Subject: Re: [TN] solder paste registration We have only seen stretch on our stencils cause a problem when they are old and very used. At this point it is best to purchase a new stencil, as it will pay for itself with reduced defects almost immediately. It may be worth while to see how the board is fixtured, as it can sometimes shift during the print cycle from time to time and cause problems. Hope some of this is useful. Ed At 10:48 AM 3/29/2002 -0800, you wrote: 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 ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------- -----