Oldy but goody, Bill. I, and who am I really, specify in my master drawing notes vias shall be tented under BGA devices - especially under .8mm CSP types just to avoid going to micro vias and all the rest going with it. I am concerned about your concerns concerning entrapped contamination (I do love aliteration) in production boards. However, this concern apparently is not being concerned by industry or is it lately in light of all this cleanliness stuff? I still want to know if we need to go back to two ply minimum dielectric materials. Seems like this CAF stuff is headed back that way. MoonMan --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------