The most important thing is the tolerance on the 50 ohms impedance, whether it is 10% or 5%, because end of the day that is what is going to affect the functionality of the board. Based on this the PCB manufacturer can compensate the line widths, dielectric thicknesses etc., as the impedance is not just a factor of the line width alone, you have the copper height & the dielectric thickness also that plays an equal role in achieving the impedance. Hence the PCB manufacturer has much more manufacturing knowledge, provided he has been given the correct tolerance & spec. to work with. You cannot tie the line width & impedance tolerance together, they work hand in hand with other factors. Thanks, Krishnan SANMINA-SCI Quality Assurance / NPI Manager E-mail: [log in to unmask] Phone (Off): 082-363000 Ext. 1602 Mobile: 012-8888-379 -----Original Message----- From: sumxp [mailto:[log in to unmask]] Sent: Sunday, September 04, 2005 2:30 PM To: [log in to unmask] Subject: [TN] 5% trace width control_RF My customer told me that one of the RF pcb need to maintain the 5mils trace width within 5% tolerance in order to achive 50 ohms impedance. My pcb maker said they can only control at 20%(copper etching process capability) trace width tolerance BUT can guarantee that the impedance is at 50 ohms. Please comment.Should I take the words of pcb supplier? rgds sumxp --------------------------------------------------- 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 ----------------------------------------------------- ____________________________________________________________________________ _ Scanned by Sanmina-SCI eShield ____________________________________________________________________________ _ --------------------------------------------------- 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 -----------------------------------------------------