Abstract: A proximity sensor assembly includes a multilayer printed wiring board proximity sensor, the proximity sensor being operable as either a variable-reluctance sensor or an eddy current loss sensor. The proximity sensor includes a plurality of layers configured to form at least one wound coil disposed about at least a portion of a core. The coils are electrically driven to generate an alternating magnetic field such that the inductance of the coils changes when a permeable or conductive object is moved in relation to the magnetic field. The change in inductance is recognized and used to detect the proximity and presence of an object relative to the sensor.

Abstract: A method of fabricating a multilayer wiring board proximity sensor includes forming a laminate, and fabricating a plurality of through-conductors through the layers of the laminate. The laminate has a plurality of layers including one or more core layers and a plurality of coil layers. Each core layer includes a core pattern formed of a permeable material, and each coil layer comprises at least one coil trace formed of a conducting material. Thus, the through-conductors may be fabricated through the layers of the laminate such that the coil traces are interconnected by the through-conductors to thereby form one or more coils disposed about at least a portion of the core patterns of the core layers.