The current rating is largely determined by the track width and how warm the track is allowed to get.
- For prototyping PCBs with 85mil tracks that are wide (no narrow places) (e.g. BR1, StripBoard STx, PR3U, PowerBoard) we recommend 3 Amps max. This allows for about a 10 C. rise in track temperature.
- For prototyping PCBs with narrower sections between the holes where the width goes down to 40mils (e.g. SB4, SB5, SB400, SB404, SB8300) we recommend 2 Amps max for a 10 C rise.
See the BusBoard application note "BPS-AN0004 PCB Current Capacity.pdf" for more information on how to determine the current capacity in your prototype.
Note that these are best case numbers. These numbers do not include derating to account for real-world situations where tracks and components are located closely together or an enclosure may restrict cooling air flow. Use 50% derating on these numbers to be conservative. If you need more current, you can cover the entire track with a solder bead to make it thicker, or you can use two or more tracks in parallel to get more current. Note that N tracks in parallel does not give N times the current capacity because there is more heat generated and the heat is NOT carried away N times more effectively.