In the last decade, there has been an evolution to mmWave applications (i.e., 24 to 100 GHz) for commercial, industrial, IoT, wireless connectivity and an array of automotive radars. This rapid growth of mmWave applications has created a demand for multilayer printed circuit boards (PCBs) with mmWave circuits. The transition to mmWave comes with many challenges for the printed circuit industry—primarily conductor geometries and materials, since the shorter wavelengths reduce feature sizes and magnify the relative tolerances inherent in the PCB manufacturing processes. This article aims to help engineers design mmWave PCBs with good manufacturability and consistent electrical performance and to avoid some common design errors. Considering all key areas of PCB design, we introduce critical dielectric and conductor material properties, along with manufacturing process challenges.

Controlling production costs can be a complex engineering challenge. Cost must be incorporated into the electrical design from the very start, since this is where materials, substrate architecture and PCB technologies are defined. Like all good engineering, the goal is to design a product meeting all performance requirements with high yield, accounting for all material and manufacturing tolerances—resulting in a trade-off between cost and performance.