Non-Contact PIM Measurement Method for Electrical Connection Inspection

A non-contact inspection method using electromagnetic intermodulation is proposed for electrical connections. It uses heavy intermodulation, which occurs at the connection with high current density. In the proposed method, a small probe at the tip of semi-rigid coaxial line excites the DUT and detects the intermodulation signal via the near field, which is effective to achieve high spatial resolution. In this paper, a small monopole and a small loop are used as the probes and their capability are examined through the experiments. The evaluation result of a packaged substrate is also shown as an application. To evaluate the capability of the proposed technique, an electrical contact is used as a defected connection. As a sample of other kinds of noise sources, the sample containing a ferromagnetic material in part is also evaluated. The results show that the loop-probe wrapping around the DUT is effective to detect the PIM source even in a continuous material, and the monopole-probe is effective to evaluate electrical-connection failures.