Splitting Conductors of Coils on PCB for AC-resistance Reduction

Coils built on printed circuit boards (PCBs) have been widely used for transformers and inductors because they have the advantages of downsizing and consistency for mounting components on the PCBs. However, copper loss caused by the skin and proximity effect takes a large proportion of the total loss of the inductors at high-frequency regions. Thus, reducing copper loss is one of the significant issues for the inductors to reduce the power loss on the coils. This paper proposes a method to suppress copper loss (AC-resistance) due to the skin and proximity effect by splitting patterns of a coil and swapping them at the corner of the coil. The proposed structure for the coil is characterized as having no via, which results in an increase in cost and copper loss. The simulation results demonstrate that a 12-corner coil shape with a splitting pattern into three sections suppresses the resistance by 16.7% compared to a spiral coil and improves the quality factor by 10.9%. Practical experiments have revealed that the optimized 12-corner coil improves resistance by 24.6% and the quality factor by 18.7%.