Hi JoAnn, A lot factors have to be taken into account but in my humble opinion, everytime you neck a trace you raise the temperature of the necked section and in effect create a fuse condition. Keep the necks as short as possible and lay a duplicate trace or double the copper. Ted Nathan Sr PCB Designer [log in to unmask] ---- DesignerCouncil(a)ipc.org's Message ---- Now that I have EVERYONE'S attention.........I have some questions about necking down conductor widths. My boss and I were talking yesterday about several isues that have arisen lately. One of them was a question one of our product engineers (senior tech) had about necked down widths on conductors on one of his products. If we have determined that we need a 15 mil wide trace (by using the conductor width nomograph in the IPC spec), is it safe to neck it down to 10 mils for a short distance? If so, define short. Or do we assume that 15 is the absolute narrowest a trace can be for ANY distance? If we can, how can we determine what is a safe amount to neck something down for a short distance. The way Cadstar handles conductors is to assign them a "track code" and then that code is given a full width and a necked width dimension. Some of the necked widths (not set up by me) are as much as 50% smaller than the full width. Is there a "standard" of some sort that we should have been using? Would anyone out ther like to tell me what they use? I'm open for suggestions. And as a little personal note - Frank Kimmey and Bob Vanech - where were you two this morning? I tried calling each of you at about 8:45 EST. No response. My first line of defence was AWOL! Hope this means you're sitting by a pool somewhere with a long icy lemonade! My thanks to everyone who can help me. Jo JoAnn L. Amerson Design Librarian Red Lion Controls, Inc. E-mail: [log in to unmask] Voice: (717) 767-6961 ext 6308 ################################################################ DesignerCouncil E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE DesignerCouncil <your full name> To unsubscribe: SIGNOFF DesignerCouncil ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ DesignerCouncil E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE DesignerCouncil <your full name> To unsubscribe: SIGNOFF DesignerCouncil ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################