R. Christopher Lott wrote: > First of all, I'm an engineer and don't do board layout every day. > Please forgive what may be a dumb question... > > I have a nagging recollection in my mind that PWBs designed to > MIL-STD-275 (now IPC-D-275) had a special requirement on the > conductor routing. Namely, that all conductor traces have to > begin and end on a land. That is, no conductor "tees" are > permitted. > > Now that I may be making such a board, I reviewed both MIL-STD-275 > and IPC-D-275, and don't find this to be the case. The only remotely > similar remark is in section 5.3.1.2 Conductor Routing (from the IPC, > but the MIL-STD has very similar wording): > > "The length of a conductor between any two lands > should be held to a minimum." > > You would be really stretching things to get my "no tees" rule from > that section. > > Question: Am I really losing it (entirely possible), or is/was there > such a rule, and if so, where is it and under what circumstances is/was > it invoked? > > Thanks, > > -Chris Lott > > -- > > ************************************************************************ > R. Christopher Lott, P.E. [log in to unmask] > Huntsville, Alabama > ************************************************************************ > > ################################################################ > TechNet 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 TechNet <your full name> > To unsubscribe: SIGNOFF TechNet > ################################################################ > 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 > ################################################################ Chris, I don't think your losing it, if so well...... I'm not sure about the D-275 std because I don't have one handy but, tee's are OK as long as you don't create a problem with signal integrity. What I mean is, if your working on an RF board or some other high speed board/signal, you probably don't want tee's. If the signals are not fast edges, then the tee shouldn't hurt. Someone will correct me if I'm wrong, (and I may be) but when processing boards back when..... The tee's and 90's would trap the chemicals and cause problems. Now that being said, I don't really know just how true that was. Someone told me that and could have been pulling my leg. (Maybe that's why I go in circles so much?) On a personal note, I don't use tee's if I can help it. I just don't like them, they look funny... Hope this helps. -- Scott Decker AKA: PadMasterson Praegitzer Design On Location at Enterprise Server Group CO3 Intel Corporation Ph: (503)-677-6582 E-MAIL: [log in to unmask] ################################################################ TechNet 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 TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ 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 ################################################################