Electrical guidelines for PCB design

Minimum distances on printed circuit boards
The following table gives only approximate values, the information is of course no guarantee. The values listed below are valid for "normal" middle European conditions and protected from weather influences. In severe conditions (moisture, chemically polluted air, high altitude, high temperature ..) are valid other values.
Voltage between conductors in V Minimum distance without solder mask in mm Minimum distance without solder mask in mil Minimum distance with solder mask in mm Minimum distance with solder mask in mil
0-29.99V 0.64 25 0.254 10
30-49.99V 0.64 25 0.38 15
50-99.99 0.64 25 0.50 20
100-149.99V 1.27 50 0.50 20
150-299.99V 1.27 50 0.76 30
300-499.99V 2.54 100 1.52 60
>499.99V 0.05mm/V 0.2 mil/V 0.003 mm/V 0.12 mil/V
It should be noted further, that after complete Montage the solder joints and the components can be protected extra to defuse the situation.

Current carrying capacity of traces
The following table provides only approximate values. In the current carrying conductor tracks a large number of factors have to be taken into consideration. The exact calculation for each case is very complex. The information is provided without warranty. The values listed below are valid for "normal" middle European conditions and protected from weather influences.
At higher temperatures are valid reduced ampacity.
Think of the heat removal from the circuit board. The following values are valid for up to 30 degrees Celsius. When the current capacity doesn't enough, then create a through-hole printed circuit board whit traces on two levels one above the other.
Trace width (mm/mils) Current carryng capacity at 17.5um/0.5OZ (A) Current carryng capacity at 35.0um/1.0OZ (A) Current carryng capacity at 35.0um/2.0OZ (A)
0.2mm / 8mils 0.5 1.0 1.5
0.5mm / 20mils 1.2 2.0 3.2
1.0mm / 40mils 2.0 4.0 6.2
1.5mm / 60mils 3.0 5.0 8.1
2.0mm / 80mils 3.3 6.0 10.0
4.0mm / 160mils 6.0 10.0 16.00
6.0mm / 240mils 8.3 14.0 22.0
10.0mm / 400mils 12.0 21.0 Not useful

3 Amp current applied on 60 mils wide track(35um/1 OZ copper) will heat it to approx. 10 °C above room temperature. !!

Current carrying capacity of vias
Holes where through-hole components are soldered, are amplified electrically by the connecting wires of the components, therefore play no role in this regard.
Drill diameter mm Allowed current (A)
0.4mm / 16mils 2.5A
0.5mm / 20mils 3.0 A
0.6mm / 24mils 3.5 A
0.7mm / 28mils 4.0 A
0.8mm / 32mils 5.0 A