Multilayer printed-circuit boards (PCBs) allow circuit designers to think in three dimensions, stacking circuits in a tight volume rather than stretching it in a planar configuration. The savings in space requires some knowledge of how multilayer circuits are fabricated—in particular, how prepreg materials are used between the circuit layers to form one reliable structure. Multilayer circuits can even be formed with different transmission-line technologies, such as stripline and microstrip, within the same structure, but choosing the right prepregs for a given board material is a critical step. To learn more about multilayer circuit design and prepregs, click here.