Earl, Can you please direct me to a WebSite that offers literature on how to calculate impedance. I have seen cards that have an impedance coupon. During the cross section I need to verify that the layup was conducted to print. Also how can I tell which layers are the impedance critical. Tks. victor, -----Original Message----- From: Earl Moon [mailto:[log in to unmask]] Sent: Thursday, July 04, 2002 6:48 PM To: [log in to unmask] Subject: Re: [TN] TDR test reports Started designing and making impedance boards in 1983 for Magnuson Computers in the Bay Area. Lee Ritchey was the man there. I required, then as now, specific MLB constructions with clearly specified materials, on the master drawing, as well as TDR testing as you do now with traceability not only concerning the electrical part of the equation. Also required, then as now for all my one or two clients since then, correlation and traceability of TDR to the materials and MLB construction shown in X-Section. This I do because it ties all the ends together and is very important for those not so knowlegeable, yet, about all that goes on in the design and fab processes. MoonMan ---------------------------------------------------------------------------- ----- 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 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/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 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------