pcb design for 220v

[cosminnci]

Hello,

I need to design a pcb which senses voltage presence (220v) the circuit would be 2 1206 resistors and an smd rectifier bridge.
the pcb receives a null and 3 different phases R S T but only 220v
what are the minimum isolation requirements between traces?

thank you.
regards,
Cosmin

[jmdejoanelli]

Cosmin,

Check out page 39 of IPC-2221 (google: "IPC-2221 filetype:pdf" to find a free copy )

Electrical clearance requirements are based on multiple factors, the main ones being Elevation of operation, PCB trace coating and peak voltage potential obviously.

You mentioned that you will be working with 220 V. I assume you mean mains, i.e. AC, in which case the peak voltage is actually 220 * sqrt(2) =~ 311 V.

Another thing you need to consider is the voltage rating of the SMT resistors you plan to use. Normally, for a 1206 package, 200 V is near the upper limit, so you might want to think about dividing the resistance across a few series resistors to increase your effective resistor breakdown voltage.

Cheers,
Josef