It is doable IF it is co-designed with the fabricator understanding the usual and expected material deviations and etch factors; also, a tight tolerance on a wide line is more achievable than a tight tolerance on a narrow line because the absolute value of the tolerance is larger and etching tolerance is dependent not on line width but on copper foil depth. Copper thickness, dielectric thickness and consistency, line nominal width, etc all need to be dialed-in to target spec for a 50 ohm (or 100 Diff) nominal. (I hope I ma clear on this item, it is the most important). As Deac also notes, there needs to be correlation established between the fabricator's test equipment and methods, and the customer's. .. Then the 1.33 Cpk is also possible and what would fall out of that would be processing outside of normal process windows, for instance, someone sets the etcher on the wrong speed for the copper foil thickness ... (operator errors being the biggest outside the process factor). My 42 cents'; worth. Valerie Deac Descoteaux <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 02/14/2006 02:58 PM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to Deac Descoteaux <[log in to unmask]> To [log in to unmask] cc Subject Re: [TN] Impedance Spec +/-5% and Cpk of 1.33 I it difficult but doable. It would be interesting to see how the customer measures the impedance as well? -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Jeffrey Bush Sent: Tuesday, February 14, 2006 2:28 PM To: [log in to unmask] Subject: Re: [TN] Impedance Spec +/-5% and Cpk of 1.33 This depends on the materials, dielectric and line dimensions which contribute the standard deviation. Generally +/-5% is difficult to achieve, although we have a few designs that are capable @ a 5% tolerance. Jeffrey Bush Director, Quality Assurance and Technical Support VERMONT CIRCUITS INCORPORATED 76 Technology Drive - POB 1890 Brattleboro, Vermont 05302 Voice - 802.257.4571 ext 37 Fax - 802.257.0011 <http://www.vtcircuits.com/> -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Glenn Pelkey Sent: Tuesday, February 14, 2006 2:06 PM To: [log in to unmask] Subject: [TN] Impedance Spec +/-5% and Cpk of 1.33 Hi folks, Is the industry capable of this requirement? Impedance +/-5% with a demonstrated Cpk of 1.33. This could apply to Single Ended 50 ohms or 100 ohms Differential. Also, this is on a Flex Circuit. Thanks, Glenn --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------