Hi, As far as I remember IPC allow 10% variations in copper thickness.Take into account that 2 oz is unit based on weight while you are describing thickness.Add to this topography of the foil from lamination side, thickness reduction as result of different surface preparation processes - it seems you need X-mass miracle to get to 4% while you are expecting 0.4%. Good luck and Happy New Year Edward > -----Original Message----- > From: Carl VanWormer [SMTP:[log in to unmask]] > Sent: ד דצמבר 24 2003 17:16 > To: [log in to unmask] > Subject: [TN] Question on 2-oz Copper uniformity for current sense > resistor > > I have a project that seems to be a good candidate for a current sense > resistor made as a part of the PCB. I am using the free calculator, > PCBTEMP, from the UltraCAD website (http://www.ultracad.com/calc.htm) for > geometry calculations. I need to know the expected variability in > thickness, > batch to batch, for the copper foil on 2-oz stock. I can live with the > 0.4% > TC of the Cu, but I need to evaluate all the other variables in my error > budget before I present my proposal. I would appreciate any success (or > horror) stories from people who have (not) used the board copper as a > current sense method. > > Thanks, > Carl > > > > Carl Van Wormer > Cipher Systems > 1815 NW 169th Place, Suite 5010 > Beaverton, OR 97006 > Phone (503)-617-7447 Fax (503)-617-6550 > > --------------------------------------------------- > 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 > 847-509-9700 ext.5315 > ----------------------------------------------------- --------------------------------------------------- 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 847-509-9700 ext.5315 -----------------------------------------------------