I have had to solve this issue on a number of occasions. The way I do it is to cut a stencil 2 mils thick for the via in pad BGA areas and then stencil down solder paste with a water soluble flux base and reflow, this acts as "spackle" and fills up the via in pad. Then clean the board and assemble normally. John John Burke (408) 515 4992 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Macko Sent: Friday, August 31, 2007 9:53 AM To: [log in to unmask] Subject: Re: [TN] vOID IN Micro BGA I will 2nd that. I have experienced a lot of voiding issues when there are VIPs on uBGAs as well as other BGAs. Often the VIPs are the same size whether they are located in a uBGA pad or a larger say 25 mil BGA pad and consequently, its impact is significant. I am trying to get the design group to always plug and cap all VIPs so this does not become an issue. One work around is to use a 2 mil stencil and paste/reflow the side of the board with this issue prior to populating any side of the board! The 2 mils of paste helps fill the VIPs as long as they are not too big. Adding an additional reflow to a non-populated board should not be an issue but needs to be verified. Good luck, - Joe -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev Sent: Friday, August 31, 2007 9:04 AM To: [log in to unmask] Subject: Re: [TN] vOID IN Micro BGA The presence of vias in the pads causes it. Mind, though, that even such large voids might not affect a long time reliability of the joints. Regards, Vladimir -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of shankar rao Sent: Friday, August 31, 2007 11:49 AM To: [log in to unmask] Subject: [TN] vOID IN Micro BGA Dear All, We are getting Large voids in Micro BGA on someof the pads having PTH/via (greater than 40% in dia) after reflow soldering in one of our multi layer PCB. We are using ROHS paste and ROHS component. Can I know what may be the reason for these voids Regards SHANKAR K. Shankar Rao --------------------------------- Unlimited freedom, unlimited storage. Get it now --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------