Ofer - Why not use .0098" drill with .020" pads? 11:1 aspect ratio plating should not be a problem for high-end board fabricators. You should also be teardropping the pads for this combination to ensure .002" at the pad-to-trace junction. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Ofer Cohen Sent: Wednesday, March 09, 2005 3:09 AM To: [log in to unmask] Subject: [TN] Shapes of pads Hello, guys, The problem - BGA with pitch of 1 mm and components in 0402 packages just under the BGA. The thickness of the PCB - 110 mils (2.7 mm), hence of through vias drilling diameter is 12 mils (aspect ratio - 1:9). To keep annular ring of 5 mils the pads diameter is 22 mils. To place components between two adjacent vias I allowed 24 mils square pads over the via holes with deep hole plugging (50% to 80% hole length). The plugging was pretty good (as seen in cross sections) and the soldering results were also not too bad, although required some touch up. This was acceptable for the production of low to medium volume. We are going now to manufacture in high volume. The solution is not economical any more. Hence, I am considering three options, all of them requires us to place pads for the components between the vias holes: 1. Round 24 mils pads. 2. Round 20 mils pads with tear drop to enhance the area 3. 19 mils square pads Since the design will port in no time to LF soldering, but I can't test it now due to lack of time and components - can you advise which is the best solution? Regards Ofer Cohen Manager Quality Assurance, Reliability and Production Technologies Seabridge Ltd. - A Siemens Company --------------------------------------------------- Technet Mail List provided as a 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------