High-Frequency Bus Bars for 3-D Packaging GaN-based LLC Resonant Converter

Three-dimensional (3-D) packaging is a technology that can be used to increase the power density of power converters. However, the vertical stack-up might cause problems of ringing, thermal management, and power efficiency. To find out the important factors in designing bus bars for vertical stacking, high-frequency bus bars using copper strips, printed circuit board (PCB), and flexible printed circuit board (FPCB) are designed and tested on a 3-D packaging LLC resonant converter with a power density of 4.5 kW/in
³
and switching frequency of 1MHz. The parasitic inductance, temperature, and power efficiency are analyzed measured and calculated. The peak efficiency of the LLC converter with the optimal design can increase by 0.7% compared to using simple copper strips for interconnection.