Laser Welding Process and Packaging for Magnetic Field Sensors
A manufacturing process for the production of miniaturized magnetic field sensors based on the GMI-effect (giant magnetoimpedance) in a thin wire of an amorphous Fe78Si7B15 alloy connected to Cu wires by laser welding is described. Due to the strong inclination of the amorphous structure to recrystallization already at a temperature far below the melting point a thermally optimized welding process is decisive for the success of the manufacturing process. The thermal load in the GMIwire in terms of the temporal temperature distribution caused by the laser welding process has been studied using transient thermal simulation. The length of the wire ends in the vicinity of the welding points in which recrystallization is believed to destroy the GMI effect is estimated. The results show that the length of the remaining active part of the GMI wire can be controlled by the energy and duration of the laser pulse and to a certain extent by the thermal properties of the substrate material. This study should help to understand the influence of welding parameters on the sensitivity of the sensor. The results of the thermal investigation are discussed with respect to the sensitivity of our GMI-sensor prototypes obtained from magnetic field measurements.
Rf and uhf giant magnetoimpedance effects in soft magnetic fibers and wires
We have investigated the giant magnetoimpedance (GMI) effect in fibers of different soft magnetic materials and in Permalloy wires. The fibers have been tested in the radio frequency (rf) range, by measuring the voltage drops in different parts of the circuit. The wires have been tested in the ultra high frequency (uhf) range, by measuring the transmission coefficient s/sub 21/ of coaxial lines having as central conductor a HyMu80 wire. The two methods provided quite similar results showing a strong GMI effect for very different magnetic samples.
Chemical Metallurgy: Principles and Practice
Foreword. Preface. Acknowledgements. Appreciation. 1. Acquaintance. 2. Mineral Processing. 3. Thermodynamics and Kinetics. 4. Pyrometallurgy. 5. Hydrometallurgy. 6. Electrometallurgy. 7. Energy and Environment. Subject Index.