GB786299A - - Google Patents

Abstract

786,299. Semi-conductor devices. SIEMENSSCHUCKERTWERKE AKT.-GES. June 28, 1955 [June 30, 1954], No. 18661/55. Class 37. [Also in Group XXXV] A Hall effect device comprises a thin wafer 2 of semi-conductor embedded with its connections in a protective member 1 of electric insulating material. The semi-conductor wafer may be ground or etched to a desired thickness while embedded in the material. Further means to facilitate the production of very thin wafers includes providing a layer of plastic material between the lower surface of the wafer and the insulating member, or strengthening the member by additional ribs during the grinding operation, and then removing these ribs from the member, since in the finished device, the latter is required to be thin in the direction of the magnetic field. Connections 10 and 11 between the Hall electrodes and tags 12 and 13 are twisted to eliminate induction effects. In an alternative arrangement, lead 10 is connected to electrode 8 by two parallel leads each surrounding half the wafer 2. The semi-conductor may consist of AIII-BV material. The insulating member may consist of a castable resin such as an ethoxyline or polyester resin, or of a ferrite or other non-conducting magnetic material, or of a mixture of a ferrite powder and a castable resin. Cooling of the device may be facilitated by using for the protective member, material of good thermal conductivity, such as a castable resin having quartz seal or non-conductive metal oxides added to it. In addition, the protective member may be extended beyond the semi-conductor wafer to provide a cooling surface, or projecting cooling plates may also be embedded in the member. The core used in producing the magnetic field may be utilized for heat dissipation. Specifications 719,873 and 759,047 are referred to.