Hi Tilak, I have thought about this myself in the past - the PCB lends itself to many such things, like built in resistances, capacitances, inductances, even batteries - but see some problems other than those already = mentioned: 1. PCB manufacturing tolerances - particularly in the case of tracks on the outer layers, plating will vary from area to area, and board to board, so that even the current threshold will not be 100% predictable. Also tracks on inner layers will have different temperature characteristics, obviously. 2. Performance of PCB 'fuse' - will this really meet your _specifc_ performance needs, not just current threshold? 3. Perhaps worst of all - environment: you would be depending upon the destruction through heat of a copper trace. The environmental effect upon exactly what current in a specific situation would be needed, would be considerable, unless you can guarantee a very small window of operating temperatures. It could be possible to use a different process, such as carbon printing (usually used for coating the contacts on keyboards, for example), to 'print' a certain resistance onto the board. This may solve problem 1, perhaps part or all of problem 2, but you still have problem 3 to deal with - unless you build in the 'extra feature' of air conditioning ;-) The suggestion that you may find a 'real' component small enough is definitely worth chasing - the 'Littelfuse' range includes some pretty small fuses (the internet is 'worth its weight in gold' in this respect = - go google it). ____________________________________ Sol Tatlow, M.Eng. (Oxon) ProDesign Electronic & CAD Layout GmbH Product Developer Albert-Mayer-Str. 16 D-83052 Bruckmuehl Phone: +49 (0) 8062-808-302 Fax: +49 (0) 8062-808-333 Mailto:sol.tatlow@xxxxxxxxxxxxxxxxxxxx www.prodesign-europe.com ____________________________________=20 -----Urspr=FCngliche Nachricht----- Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] = Im Auftrag von Gaitonde, Tilak Gesendet: Mittwoch, 25. August 2004 12:17 An: Si-List Betreff: [SI-LIST] Can a thin PCB trace be used as a reliable fuse Hi Masters, This is really not an SI related query, but comes under electronics = design.=20 My query is this. Can a thin PCB trace be used as a reliable fuse. I = have a real estate problem on my PCB & require 4 fuses with current threshold = of 6A. I searched for the components & found they too huge to use on the = PCB. So thought I can use trace as fuse!!=20 If it is possible is there any paper that has this explained?=20 Please help. Thanks, Tilak ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: =20 http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu