Hi Stacy, First thing that comes to my mind is the type of solderpaste. Not only the size of the solder particles is important, but you also need a modern flux chemistry that assures easy release of the paste from the stencil apertures. I'm quite happy with Alpha UP78T. Daan Terstegge SMT Centre Thales Communications Unclassified mail Personal Website: http://www.smtinfo.net >>> My Nguyen <[log in to unmask]> 12/11 7:43 pm >>> Hello all, Problem description: Been happening on Rambus - part number tc59rm81xmb. Ball diametter: 0.5 mm; ball pitch: 0.8 mm, ball height: 0.4 mm. Pad size: 0.3 mm (11.5 mils) 5-10% of the time (we run huge amount of them) failure modules came from opening soder join or no solder join at all. As we inspect the screen printing process (we use 5 mils stencil - Dek screenprinting, cleaning rate: 2 per print, cleaning cycle Wet-Vacuum/Dry), we found un-event solder deposit. Some pad even has very little solder or no solder at all. Stencil is electro-polish; Diamond shape aperture, 13.5 mils open used trapezoid shape. We afraid that if we open the apperture bigger, then we may have bridging or solder ball. If we reduce the stencil to 4 mils to reduce the blockage or resistance, then we may have in-efficient solder or many other problem relating thin stencil (damage, short-life, etc) What would be your solution? Thanks, Stacy __________________________________________________ Do You Yahoo!? Check out Yahoo! Shopping and Yahoo! Auctions for all of your unique holiday gifts! Buy at http://shopping.yahoo.com or bid at http://auctions.yahoo.com --------------------------------------------------------------------------------- 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 the following message: SET Technet NOMAIL 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 --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- 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 the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------