This paper is focused on design and realization of planar inductive sensor system used for proximity sensing based on Low Temperature Co-fired Ceramics (LTCC
Keywords planar inductive proximity sensor, planar inductor, LTCC technology
IntroductionActual trends in electronics industry give demanding requirements on sensors used for process and devices control. Depending of sensing application, immunity against environment impact, reliability and long life cycle, robustness, small physical dimensions, low energy consumption and low manufacturing price are the main requirements for modern sensors and sensing systems. Inductive sensors meet these requirements. Event counting (rotary speed detection, flow meters), simple buttons for industrial keypads, industry switches, metal detection, linear position detection, angle detection, engine tests (valve position), roller gap process control (thickness, shape, texture), quality inspection (deformation, cracks) or vibration sensing are only some of the possible applications of inductive sensors. Because of any mechanical parts, inductive sensors are ideal option for proximity detection.Harsh environment, low available space and the need of inductive proximity sensing are the main reasons to choose an alternative to standard inductive sensors. Low Temperature Co-fired Ceramic (LTCC) system offers very good alternative for producing planar inductive proximity sensor. LTCC is technology that allows creating of multilayer modules by stacking single ceramic sheets together. Glass-ceramic composite material of LTCC tapes usually consists of Al 2 O 3 , SiO 2 and organic materials. Sheet of LTCC can be shaped and bended before firing process. LTCC tape processing is based on screen printing, laminating and firing process. Applying of conductive, dielectric and resistive pastes LTCC technology allows to integrate resistors, capacitors and inductors. Resistance against high temperatures and negative impact of given environment [1,2], ability to produce planar conductors in tenth of micrometer resolution, stacking single ceramic sheets to reduce needed length of coil winding and dimension of the coil itself [3], and an ability to operate in high frequency area predetermines using LTCC as a basic substrate for planar inductor coil. High reliability and stability of realised structures and excellent electrical characteristics [4,5] predetermine LTCC for use in sensor's applications. Reducing total size of sensing device and increasing reliability of sensing module can be achieved
