Printed circuit boards (PCB) are subject to external electromagnetic interference. A validation tool to efficiently predict the worst-case induced voltages and currents is invaluable in the process of making PCB designs pass the immunity test for electromagnetic compliance. This paper proposes to use a 2.5-D hybrid finite-element-method (FEM) solver to characterize the radiated far field and use the reciprocity-based method to calculate the induced port voltages and currents due to an incident plane wave. This method can be used to analyze any full-size PCB. Good agreement with the results from a 3-D full-wave FEM is obtained at low frequencies, where the 2.5-D assumption for the fields in the PCB applies. Furthermore, the calculation time and memory consumption are significantly reduced.