Hi IPC does not allow for a 20% reduction of the copper features, 13mm or 10% of a track can deviate up to 20% for class 2 and 3. I don't think this is well formulated as it doesen't really allow for manufacturing tolerances, I believe most manufacturers interpret this in a more liberal manner and considers 20% as the manufacturing tolerance. However, to let the 20% be valid for the larger copper features is a bit thick in my opinion. I interpret the maximum allowed reduction on pads as the absolute reduction on conductors. Meaning that if the board has 0,1mm tracks the maximum allowable reduction on pads is 0,02mm. Best regards Grunde _________________________________________________________________ CONFIDENTIALITY NOTICE The information contained in this e-mail and any attachments to it are intended solely for the person(s) and/or organization(s) named above and is confidential. Unauthorized use, copying or disclosure of any of the information is unlawful. If you have received this e-mail in error please destroy it and contact the sender on the numbers given above. We would be happy to accept a reverse charge call (call collect). Ryan Grant <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 30.06.2008 21:43 Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to [log in to unmask] To [log in to unmask] cc Subject Re: [TN] IPC-6012A - allowable conductor width reduction interpretation? Hi Joe, I interpret it the same and end up specifying specific BGA pad size tolerances instead of using 6012. By the way, per IPC, the conductor width should be measured from the bottom of the pad, i.e. the interface between the copper and dielectric. There is typically a 25um difference in width between top surface and bottom surface, so measurements of pad width that only measure the top surface might seem smaller than allowed. Thanks, Ryan -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Macko Sent: Monday, June 30, 2008 10:45 AM To: [log in to unmask] Subject: [TN] IPC-6012A - allowable conductor width reduction interpretation? All, IPC-6012A with amendment 1, section 3.5.1, Conductor Width and Thickness states, "When not specified on the master drawing the minimum conductor width shall be 80% of the conductor pattern supplied in the procurement documentation". The PCB suppliers interpret this to mean that BGA pads for example can be 80% of the pad diameter specified in the procurement documentation, which is the GERBER files unless specified otherwise and still be acceptable per IPC-6012. I am interested to hear how other users handle allowable reductions in BGA pad size from that specified in the procurement documentation. thanks Best Regards, -joe --------------------------------------------------- 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 -----------------------------------------------------