Hi, We have non-conductive resin filled and capped micro-via (via-in-pad) through the complete PWB thickness (1.6mm FR4) 8-layer, we have seen considerable voiding in the BGA balls following assembly: Q1) What is the chance of out-gassing from the PWB board (or specifically the filled capped via) going into the BGA ball and creating a void during reflow. Q2) What is adequate flatness on the PWB surface considering “dish-down” of the filled resin during via filling and before Cu plating. I think the IPC spec. is 70% but does anyone have differing experience of this. Q3) Would a fairly “rough” topology on the surface of the capping plating (i.e. not totally flat, bumps etc) cause any difference in the solderability, I believe that: · The via drilled diameter is 0.25mm · PWB finish ENIG, · Cu/Ni/Au plating thickness is 20um · The PWB thickness is 1.6mm · The PWB Tg is approx 170 deg-C · The paste is Pb-free, · The reflow profile is good to the paste suppliers recommended profile, · The PWB’s have been baked-out 130 deg-c 24-hours before assembly, · Reflow peak reached 242 deg-C · Reflow soak 170 deg-C for 170 seconds, There are large and small voids in the BGA balls during X-Ray and cross sectioning. Some of the BGA balls apear slightly elongated not correct shape. In essence would you think that it would be a PWB issue or assembly problem. Any feedback would be much appreciated. Thanks, D. McCall. mailto: [log in to unmask] _________________________________________________________________ Save time by using Hotmail to access your other email accounts. http://clk.atdmt.com/UKM/go/167688463/direct/01/ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------