Low Temperature Co-fired Ceramics (LTCC) is one of the microelectronic techniques. This technology was initially developed as an alternative to Printed Circuit Boards (PCB) and classical thick-film technology, and it has found application in the fabrication of multilayer ceramic boards for electronic devices. Fast and wide development of this technology permitted the fabrication of 3D mechanical structures and integration with various different processes. Thanks to this, LTCC has found application in the manufacturing of various microelectronic devices. This paper presents an overview on LTCC technology and gives a detailed summary on physical quantity sensors fabricated using LTCC technique.

In a three-step development process CaCu 3 Ti 4 O 12 -based bulk ceramic pellets, tape-casted multilayer ceramic laminates, and multilayer ceramic capacitors with cofired electrodes were fabricated. The sintering behavior, microstructure, electrical resistivity, and dielectric properties were studied. At a firing temperature of 1050°C, an effective permittivity of about e 0 = 60 000 and 10 000 was observed for sintered pellets and multilayer laminates, respectively. The typical grain growth observed in pellets is suppressed in multilayer laminates. Impedance spectroscopy was employed to show that the bulk grain resistivity is similar in pellets and multilayer laminates, but the grain-boundary resistivity is higher in pellets. Tapes were processed into multilayer capacitors with Ag/Pd electrodes and cofired at 1050°C. All three types of samples, pellets, laminates, and capacitors were also processed with a glass additive, in which case they can be cofired at a lower temperature of 900°C. In glass-containing pellets, the temperature dependence of permittivity is weak and exhibits X7R characteristics for frequencies below % 60 kHz. Our results demonstrate the high potential of CaCu 3 Ti 4 O 12 for application in monolithic as well as in integrated multilayer capacitors.A. Feteira-contributing editor Manuscript No. 34996.

Neurobiological concepts based on state-of-the art technology have so far lacked the complexity of actual high-level neurobiological systems. Two key advances are needed to improve our understanding of such systems: in vitro 3D-neuronal cell culture and 3D MEA systems for measuring such 3D-cultures. These requirements call for smart multilayer and packaging technology. The material Green Tape TM from DuPont Nemours is chosen for the presented works, because its compatibility and those of available metallisation with cell cultures is already proven. An LTCC multilayer circuit with gold electrodes is the base of the 3D MEA. The layout of the 3D MEA is designed to fit the MEA2100-System for in vitro recording from Multi Channel Systems and enable thus a comparable data processing to established 2D MEAs Slots. The surface topography of the thick film electrodes and the surface state is investigated with laser scanning microscopy, SEM, XPS and measurements of the wetting angle of contact. The impedance of the screen printed electrodes is discussed taking these data into account. Their impedance amounts to 24 kΩ and are falls thus below the impedance of commercially available electroplated gold electrodes of 30 kΩ. First promising results have been achieved using 3D MEAs for 2D culture of human pluripotent stem cell derived neural cells.

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