A sensor for measuring the stress-induced displacement of metallization in plastic molded semiconductor devices is discussed. At the chip surface, a local magnetic field is introduced by leading a well-known current through the central conductor. Two Hall elements integrated symmetrically along this conductor are used to measure the magnetic field. The difference in output voltage of both Hall elements is a measure for the displacement of the current's center and so of the central conductor itself. Since the measurement method is nondestructive, it is possible to observe the displacement at multiple stages of an environmental test procedure. As a result of the magnetic approach the sensor measures the central conductor's bulk displacement and hence is less sensitive to deformation of the conductor's cross-sectional area than a capacitive sensor. The sensor shows good linearity for moderate displacements (or=5 mu m). A larger linear range can be achieved by enlarging the sensor distance.
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