Power Efficiency Improvement for Low Ohm Current Sense Resistor by Optimum Thermal Management

摘要

To improve power efficiency, design engineers need to detect current throughout the circuit to minimize power loss.Low ohm current sense resistors are used to detect current to measure and monitor power. These components needto handle higher power to achieve optimal performance. In this work, we extensively studied to improve the powerhandling capability of low ohm current sense resistors, while maintaining smaller size. We optimized powerdissipation by applying innovative thermal management techniques. Employing novel packaging technique, weoptimized heat dispersion and minimized the peak surface temperature rise. Using proprietary thermal protectionmaterial, we avoided direct heat transfer from component to PC board and minimize the risk of thermal damageagainst PCB and extreme thermal cycle. We extensively discussed the thermal fatigue of resistor terminationstructure. Solid metal package construction leads to solder cracks due to thermal fatigue, hence decreases resistorreliability. We improved the packaging footprint and significantly reduced the chance of solder cracking. Weoptimized the resistor structure for current sensing and shunting purpose. We laid out electrodes and termination inparallel and minimized the contact resistance. Considering these parameters, we manufactured low ohm currentsense resistor of 0.5 milli ohm to 100 milli ohm values with up to 5W rated power with tolerance as low as 0.5%.