The study of suppression method for power radiation between GND planes from signal via in multilayer board

When a multilayer board is used to increase the signal density, via structures are unavoidable to connect signal paths. However, it becomes clear recently that high-speed via transitions cause not only impedance discontinuities but also undesirable power radiations which have the parallel plate transmission mode between ground planes. In order to solve above problems, expansion of a part of the clearance as a fan shape around the signal via is effective. This method is available to low-cost production of the multilayer board in the next generation, in the point that it is applicable to conventional low-cost substrate manufacturing methods.