TechNetters, I have a question regarding consistency of 7095 (Design and Assembly Process Implementation for BGAs), SM-782 (the Surface Mount pad document), and 7525 (Stencil Design Guidelines), resulting from discussion with process engineers and techs earlier today. We were looking at a BGA, 20x20 package, with 1.27 mm pitch. The stencil design guidelines (7525, Table 1 on p. 4), call for an aperture of 0.75 mm. That table also refers to a 0.80 mm pad. SM-782 (section 14) says a 20x20 BGA will have 0.75 mm balls that should go onto 0.60 mm pads. Do these documents contradict each other regarding pad size, and is 7525 wrong with regard to BGA stencils? Further, the bare board does have 0.60 mm pads for the BGA. 7095, in 6.2.1, p. 33, says "land diameter is usually smaller than the ball diameter..land size reduction of 20 to 25% has been determined to provide reliable attachment...". As always, thanks for any comments. Lou Hart --------------------------------------------------------------------------------- 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 recieve 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 ---------------------------------------------------------------------------------