Phillipe, Far be it for me to not weigh in on the recurring topic of 90/45/curved pcb traces. I will agree with the posters so far that there is no signal integrity reason to use anything other than 90 degree bends, except perhaps for high-voltage circuits. My reasons for using 45 degree bends are mechanical. The process of pcb manufacturing involves several cycles with wash operations between cycles. The 90 degree bends are harder to clean, retaining leftover acid and bubbles more readily than 45 degree bends(*). The results can be over-etching or cracking in the trace, or contamination of the board surface leading to leakage currents in more sensitive analog circuitry. Since most CAD packages can do 45 degree chamfers automatically, it costs nothing and results in what is arguably a more reliable board. Since your router can do curved corners, the same logic may apply. Then again, maybe your board house should be able to do a better job of cleaning between processes. But boy, I hate it when those darn electrons go flying off the bends! :-) Regards, Alan Hilton-Nickel Philippe Robert wrote: > > Hi there, > > I am currently in the process of doing a new PCB, at the routing stage. In > the router that I am using, there is an option to have 90-degree or > 45-degree angles on the tracks. I know that it is better to have the option > set to 45 to avoid changing too much the impedance of the tracks. I designed > few board using that option. > > In the router, there is an other option to have curves instead of angles on > the tracks. Theoretically, it should be better in terms of impedance as the > width of the track vary even less. > > Could someone tell me if curves are better than 45-degree angles and why ? > > Best regards. > Philippe. > > ------------------------------------------------------------------ > 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: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > List archives are viewable at: > //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 > ------------------------------------------------------------------ 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: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //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