Yes, I agree. All ED copper foils are produced to a 10% tolerance of these nominal numbers cited. We take discrete measurements of all foil thickness and these vary little from nominal. I believe the weight metric was derived from a costing standpoint rather than a thickness; we merely applied a conversion to allow for verification of the weight parameter to the circuit thickness which is critical in many applications. Jeffrey Bush Director, Quality Assurance and Technical Support 76 Technology Drive - POB 1890 Brattleboro, Vermont 05302 802.257.4571.21 http://www.vtcircuits.com -----Original Message----- From: Werner Engelmaier [mailto:[log in to unmask]] Sent: Friday, November 05, 2004 1:54 PM To: [log in to unmask] Subject: Re: [TN] copper weight Hi Jeffrey and all, Things are not quite as simple as has been portraied--the density of ED copper is not a fixed number, it varies depending on the plating details of a given batch. This is the reasopn ED Cu foil is given as a weight per area, not as a fixed thickness. The situation is further muddies, because many of these foils have a variety of adhesion "tooth" geometries. Thus, to say "copper weights in oz - 1/4, 3/8, 1/2, 1.0, 2.0, 3.0, 4.0 are as follows in microns - 9, 12, 18, 35, 71, 107, 142" is not correct. The micron numbers are only the metric equivalents of the mil numbers, BUT the mil-thicknesses are only NOMINAL values with significant +/- ranges. Regards, Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904 E-mail: [log in to unmask], Website: www.engelmaier.com --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------