re trace size for a amp supply acollins uclink berkeley edu andy collins writes how thick do i need to make a pcb trace for amps of current and does anybody have any other thoughts on the process what kind of pcb to use materials thickness of copper any advice graciously accepted in four replies i ve seen no hard numbers so here goes for traces on the outside not inner layers expect in oz copper at amps the following temperature rises versus width this is from sams reference data for engineers seventh edition pg which claims in turn to be from mil std c width temp rise inches degrees c at amps the rise for the width is only about degrees power goes as square of the current plus the copper resistance goes up as temperature goes up certainly mm traces should be ample for what you want to do and ounce copper almost cuts the required width in half i d do oz at about width myself i think given that the rated current is amps and the is a transient or fault condition there s another question will the voltage drop be low enough but you should be able to figure this one out with wire tables or just the resistivity of copper keep traces short and use separate sensing traces where appropriate as mentioned by another poster
