Learn about Passive Intermodulation (PIM) in printed circuit boards. PIM occurs in passive devices (which may include cables, antennas etc.) that are subjected to two or more high power tones. The PIM product is the result of the two (or more) high power tones mixing at device nonlinearities such as junctions of dissimilar metals, metal-oxide junctions and even loose connectors. The higher the signal amplitudes, the more pronounced the effect of the nonlinearities, and the more prominent the intermodulation that occurs - even though upon initial inspection, the system would appear to be linear and unable to generate intermodulation.