Dr. Lee: We are talking about two different matter. The positive Ion charge atoms will deposit on the cathode (opposite charges attract ) and plate the cathode, while at the same time electrons will travel to the anode from the cathode. Those ion will loose their charge once they become part of the Cathode and become plain metal. In the case of CAF, a starting parasitic current will travel from cathode to anode and carry with it mass and accumulate at the anode and build up towards the cathode till it becomes a short. Respectful Regards, Ramon -----Original Message----- From: Lee parker [mailto:[log in to unmask]] Sent: Thursday, June 22, 2006 11:49 AM To: TechNet E-Mail Forum; Dehoyos, Ramon Subject: Re: [TN] Board material Ramon I would not say your theory is wrong, but generally the ions plate to the cathode which of course has a negative charge due to a net loss of electrons. This is why it attracts ions of course. If your theory is correct then what is the nature of the deposit on the anode? Best regards Lee J. Lee Parker, Ph.D. JLP Consultants LLC 804 779 3389 ----- Original Message ----- From: "Dehoyos, Ramon" <[log in to unmask]> To: "TechNet E-Mail Forum" <[log in to unmask]>; "Lee parker" <[log in to unmask]> Sent: Thursday, June 22, 2006 10:51 AM Subject: RE: [TN] Board material The reason is simple. Current travels from Cathode to Anode and as the electron flow enters the anode, it deposits conductors at the anode side, so the anode grows towards the Cathode. An analogy would be, several rivers coming to a one river bottle neck. Each river brings debris and the obstruction builds from the bottle neck to the feeding rivers. In the case of CAFs, they probably start growing slowly and the growth speeds up as the distance between anode and cathode is curtailed. It is only my theory. Ramon \ -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Lee parker Sent: Thursday, June 22, 2006 9:34 AM To: [log in to unmask] Subject: Re: [TN] Board material Richard Actually CAF was first identified by Dave Lando who was in the same Bell Laboratories organization as Werner and myself. This was in 1974, just after we opened the new and world's largest PCB shop in Richmond. Probably the most important attribute of CAF is as the name suggest, the filaments grow from the anode to the cathode which is the opposite of what one would anticipate. Best regards Lee J. Lee Parker, Ph.D. JLP Consultants LLC 804 779 3389 ----- Original Message ----- From: "Stadem, Richard D." <[log in to unmask]> To: <[log in to unmask]> Sent: Thursday, June 22, 2006 9:06 AM Subject: Re: [TN] Board material In about 1978, when CAF was realized as a problem in standard PTH power supply boards, the strands were continuous through the pre-preg. It was then that the fab shops started to used chopped fiberglass mat weave, in order to provide shorter strand lengths so CAF formation was less likely to happen. However, because of circuitry being so close together sometimes with fairly high potential, CAF has become more of an issue again. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon Sent: Thursday, June 22, 2006 7:36 AM To: [log in to unmask] Subject: Re: [TN] Board material Hi Werner, could you expand on "Having PCB materials without continuous glass fibers makes them immune to internal CAFs"? I was under the impression that the continuous glass fibers were the strength of the board. Regards, Ramon -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier Sent: Wednesday, June 21, 2006 3:58 PM To: [log in to unmask] Subject: Re: [TN] Board material Hi George, CAF stands for 'Conductive Anodic Filament'-CAFs are capillary paths, typically from PTH to PTH, along the glass fibers of the PCB glass fiber reinforcements. The get started by damage done during PTH drilling with a dull drill, propagate further depending on internal vapor pressures, and on application of a potential difference transport metallic ions forming a conductive path. Now, this conductive path does not give you a dead open, but lowers insulation resistance by couple of orders of magnitude. Having PCB materials without continuous glass fibers makes tham imune to internal CAFs. Regards, Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 386-437-8747, Cell: 386-316-5904 E-mail: [log in to unmask], Website: www.engelmaier.com --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------