PCB routing and voltages

[jds]

I'm routing a PCB at present and it's very tight on space. Mainly this is because I'm trying to keep within the 100mm square size that is a lot cheaper to get made. This is also the first board that I have done that has a few differing voltages, mainly it's the +12 and -12 I need for the serial ports (and it also goes to an expansion connector). What I probably should have done is to start with the higher voltages and then route the other signals, but I've ended up doing it backwards, I've got all the complicated hard stuff mostly done, but now my power signals need to go in places where I'd rather not take them, like between IC pins.

I'm not sure if this is a problem on not? Ideally I wouldn't do this as the risk of a short sending high voltages where they shouldn't be is much higher, but also I've put quite a few hours into the board so far and I don't want to start again. Do you think this is something I should be worrying about?

[GARTHWILSON]

Don't worry about it. I think all board houses now can do .006" trace and space perfectly reliably without charging extra, and a .006" space would take hundreds of volts to arc, and a lot more with the soldermask coat over the traces. Also, a .008" trace can handle a half amp continuously with only 20°C temperature rise which won't damage a thing.

[tingo]

Yes, unless you are doing a lot of current (more than 2 Amps) voltages as low as 12 Volts does not need extra trace width, or extra separation.