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.
Development of amorphous thin film meander trilayers and investigation of GMI effect
Trilayer structures of 50 and 100 nm thin amorphous CoFeB layers with a central 100 and 200 nm thin Cu layer respectively were sputtered onto a thermally oxidized Si wafer. 300 /spl mu/m long strips of 3-20 /spl mu/m width was structured using a standard mask with various strip lines and meanders which were connected in series and were then formed by plasma etching. Magnetization curves, parallel to the easy axis and hard axis of uniaxial anisotropy, were measured by the magnetooptical Kerr effect exhibiting anisotropy fields of around 2 kA/m and low coercivity in the hard axis direction, depending on the film thickness. The MI effect was measured manually from 10 MHz to 1 GHz by means of a network analyzer using the reflected wave through the sample.
Bentham's Equality-Sensitive Utilitarianism
Rosen argues that Bentham's utilitarian doctrine was sensitive to distributive concerns and would not countenance sacrifice of fundamental individual interests for aggregate gains in happiness in society. This essay seeks to extend and deepen Rosen's argument. It is argued that Bentham's equality-sensitive principle of utility is an expression of an individualist conception of human happiness which contrasts sharply with the orthodox utilitarian abstract conception. Evidence for this interpretation of the basic motivation of Bentham's doctrine is drawn from his view of the relationship between happiness and expectations, from various expressions of his ‘each to count for one’ formula, and from his reformulations of the principle of utility itself late in his career.