Daan, If you specify the final etched dimensions on your print, that should supercede any IPC tolerances, and if your board supplier has a problem with those tolerances or notes then contact should be made by supplier for a deviation. Assuming that the board is being built with half ounce copper foil on the outer layers, your supplier should not have problems with maintaining +/-1 mil on a 12 mil surface mount pad. Tony Steinke tsteinke@ait-atlanta ----- Original Message ----- From: d. terstegge <[log in to unmask]> To: <[log in to unmask]> Sent: Monday, February 04, 2002 2:33 AM Subject: [TN] Tolerance on padwidth Hi Technet, IPC-6012 mentions "when not specified on the master drawing the minimum conductor width shall be 80% of the the conductor pattern supplied in the procurement documentation". This is fine for the tracks, but it may cause problems with the solderpads. Quite often I see that the 12 mil designed fine-pitch pads have a width of only 9.6 mil on the actual products, leaving a marginal process window for assembly. I can live with 11 mil instead of 12 mil, but 9.6 mil is too small for my taste. The questions: 1) Is there an additional specification for the etching tolerance of the solderpads ? 2) If we put additional requirements on the master drawing, what would be an acceptable value ? As always I'm very interested to hear your comments, Daan Terstegge SMT Centre Thales Communications Unclassified mail Personal Website: http://www.smtinfo.net ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------