Reducing the radiation from PCB cavities with a high-DK dielectric layer

A special layer of high-DK material is used to replace edge plating and/or via stitching connecting ground planes to suppress EMI and radiation from multilayer printed circuit boards. Electromagnetic leakage from gaps due to via-to via stitching and break-off tabs required in plating is minimized and overall cost is reduced. A test board is built, near field scan measurement and near to far field transformation is used to quantify the EMI suppression of the proposed high-DK layer vs. traditional via stitching. The results show comparable if not higher (up to 20dB) suppression of board edge radiation in a broadband frequency range.