"Poor release" (paste hanging-up in the stencil holes) could have three main (or combination of) causes: 1 Equipment: * Stencil is too thick. Specifically, your 0.006 should be OK, providing you don't violate the ratios in another post on this thread too wildly. * Plastic squeegees stick more than metal * Old metal squeegees stick more than new * Squeegee is heavily magnetized ;-) 2 Process: * Snap-off distance is too small. * Need enough paste for thumb-sized roll. Too little & it won't fall off. * Temperature in your screen printer needs to stable. Paste suppliers say that 1° C change can affect paste viscosity by about 10%. 3 Material: * Solder paste viscosity is too high * Solder paste is too tacky * Solder paste particle size is too large * Some pastes stick more than others * Paste needs to be worked * Paste needs to be at room temperature * Some flux formulations are very sensitive to humidity Dave Fish ----- Original Message ----- From: Rama Vemulapalli To: [log in to unmask] Sent: Tuesday, March 18, 2003 5:14 PM Subject: [TN] Squeegee blades for printers For more than 4 years, we were using Alpha metals, no clean 63/37 paste. Recently we tried the Kester paste on our DEK printers. The printing performance is far better than the Alpha Paste. So, we switched to Kester FL250D no clean paste (63/37, 90%, Mesh -325+500 , VISC 1400-1800 ). But, we are having serious unexpected problem on MPM printers. The paste does not drop from the blades after the print stroke causing big voids on the boards. We are scrapping quite a few boards due the misprints. Is there any solution for this problem ? Some one suggested 'TEFLON' coated squeegee blades. Sincerely, Rama Vemulapalli ------------------------------------------------------------------------------ Do you Yahoo!? --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop!