Progress and Recent Realizations of Miniaturized Inductive Proximity Sensors for Automation

Noncontacting inductive proximity sensors (IPSs) are widely preferred for position detection in industrial applications. Advances in computer-aided design simulation tools, integration, and assembly techniques for the last ten years have made possible continued sensor-feature improvements in parallel to size reduction toward very small miniaturized versions. This paper refers to the progress in the past years, presenting recently gained knowledge in sensing principle, evaluation electronics, and manufacturing. The most significant improvements are the usage of a drum-core topology, application-specified integrated circuit implementation, and face-down flip-chip technology. The fundamentals shown in this paper were essential for the design and development of a worldwide innovation: the smallest single-component IPS family that has the largest switching distance. Mounted in a stainless steel tube with a diameter of only 3 mm and a length of 33 mm, the smallest sensor in the family is able to detect metal targets at distances of up to 3 mm and provide an output switching signal with high-current capacity