The LLC resonant converter is widely used in various high-performance applications. Planar transformers play a crucial role in compact configurations, such as electric bicycle chargers and telecommunications devices, due to their benefits, including low profile, manageable leakage inductance, good thermal characteristics, and ease of production. Designing an LLC resonant converter with a planar transformer poses challenges in minimizing parasitic capacitance from closely spaced coils and managing leakage inductance and winding resistance. Uncontrolled parasitic capacitance can affect the converter's performance. This article delves into parasitic capacitance in planar transformers, highlighting the impact of PCB layout on parasitic capacitance values, simulating validation, and proposing solutions to reduce parasitic capacitance in planar transformers through PCB layout. Conducting experiments with two planar transformers featuring polarized and non-polarized winding structures involves evaluating the quality of parasitic capacitance in these two cases