PCB Design for Reduced Thermal Drift for Current Measurements Through Shunt Resistors

This study was conducted from the necessity to measure electrical currents through shunt resistors as precisely as possible by minimizing thermal drift. The methods used to minimalize the thermal effects, placement of sensing lines, current lines and via instalment were analysed on 6 shunt resistors placed on a PCB which was coated with black paint to normalize the emissivity of the board. The results were measured and compared using a thermal camera, at an ambient temperature of 25, at a nominal current of 20A and a voltage provided from a power supply of 5V. The results show that the most effective layout for shunt resistors for reduced thermal drift is the one with sense lines at the middle of the pads and with no misalignment with respect to the current path.