Something seems to be wrong, here. Those numbers seem way too high . . . I'm guessing that there some uncompensated lead resistances or contact resistance showing up. I calculate that a 1 inch long 1 mil wide trace of 1/2 oz. copper gives about 1 ohm. If you want some easy suggestions as to how to get better numbers, I'm sure we can come up with a lot of low-cost approaches. Later, Carl Carl Van Wormer Cipher Systems 1800 NW 169th Place, Suite B-100 Beaverton, OR 97006 Phone (503)-617-7447 Fax (503)-617-6550 -----Original Message----- From: DUTTON Phil [mailto:[log in to unmask]] Sent: Wednesday, December 15, 2004 4:14 PM To: [log in to unmask] Subject: Re: [TN] Resistive internal layers Blair, Yes the lead resistance was taken into account. Phil. -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Blair K. Hogg Sent: Thursday, 16 December 2004 12:04 AM To: [log in to unmask] Subject: Re: [TN] Resistive internal layers Phil, I'm curious, when you measured these did you use a 4-wire meter or some other method to eliminate the meter lead resistance? Blair >>> [log in to unmask] 12/14/04 07:26PM >>> Just some further findings on this particular problem; There are four through hole connector pads (A,B,C,D) in a row, each pad 0.8 inches from the next pad. There is a 6 thou, half ounce track (same internal layer) running in parallel with the four pins, about 100 thou from the pads. The four pins are connected to the pads with stubs. IE: the traces do not go through the pads The resistance measurements are as follows: A to B = 1.2 ohms B to C = 1.2 ohms C to D = 1.2 ohms A to C = 2.5 ohms B to D = 2.5 ohms A to D = 3.7 ohms Which makes the trace stub and pad/via resistance approx 0.05 ohms And the parallel trace resistance between any two adjacent pins approx 1.2 ohms The other internal layer is the same, but the A to D resistance is 2.4 ohms Some other PCBs show approx identical resistances While others have different resistance but the same ratios Some are OK None of the external traces show this effect. Even those going through vias from the top to the bottom of the PCB. regards, Phil. --------------------------------------------------- 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 -----------------------------------------------------