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Manufacturing and characterization of a deformable LTCC membrane with integrated temperature sensors, strain gauges and heating structures

: Gutzeit, Nam; Müller, Jens; Bruchmann, Claudia; Gebhardt, Sylvia

Müller, Jens ; International Microelectronics and Packaging Society -IMAPS-; American Ceramic Society -ACerS-, Westerville/Ohio:
IMAPS/ACerS 8th International Conference and Exhibition on Ceramic Interconnect and Ceramic Microsystems Technologies, CICMT 2012. Proceedings : April 16-19, 2012, Erfurt, Germany
Erfurt, 2012
International Conference and Exhibition on Ceramic Interconnect and Ceramic Microsystems Technologies (CICMT) <8, 2012, Erfurt>
Conference Paper
Fraunhofer IOF ()

The wavefront of high energy lasers can be corrected by using a deformable mirror. This mirror is a complex multimaterial device based on a LTCC membrane (DP 951) with a galvanically deposited and polished copper surface. In the membrane temperature sensors, strain gauges and heaters are integrated to measure deformation and temperature and to influence the latter. The laser wavefront is corrected by deforming the membrane with screen printed, segmented PZT thick film actuators.
In this paper the challenging manufacturing process of the mirror is described. During processing the LTCC membrane with integrated sensors must endure the postfired sintering of PZT at temperatures of up to 900°C without any degradation of the sensors' characteristics.
In order to optimize the sensors, various combinations or resistor and conductor pastes and different geometries are characterized. The usability and the performance of the sensor elements after temperature treatment are investigated by measuring the resistance and its resistance temperature characteristic.
For the detection of the membrane deformation, an array of miniaturized strain gauges is used. To achieve a controlled temperature distribution across the membrane different buried heater concepts are manufactured and characterized.
In order to improve the mechanical stability of the membrane, a rim of fired LTCC (width: 6mm, diameter: 52mm, thickness: 600µm) is bonded to the multilayer membrane using a sealing glass.