| abstract |
881,834. Semi-conductor devices. WESTERN ELECTRIC CO. Inc. Oct. 29, 1957 [Oct. 31, 1956], No. 14256/61. Divided out of 881,832. Class 37. A lead of gold, silver, aluminium, copper or gold-plated or tinned copper is bonded to a strip of gold or aluminium 1 mil. wide on a semi-conductor body by pressing the parts together at a temperature above 100‹ C. but below the lowest eutectic temperature of any combination of the materials in contact, and the dislocation forming and displacing temperatures of the semiconductor, and maintaining the pressure and temperature long enough to make a strong low resistance bond. In an example, 1 mil. wide strips 44, 46 of aluminium and gold respectively are first alloyed to a mesa 52 formed on a germanium or silicon block. Leads 48, 50 of gold and aluminium respectively are then pressed against the alloyed strips in a press for 5 seconds to 15 minutes under a pressure sufficient to deform the leads by from 10 to 20%. The electrodes thus formed constitute the emitter and base respectively of a transistor. The press consists of a head with a wedgeshaped or pointed lower end movable transversely and vertically with respect to a press bed. Both the head and the bed of the press are heated by electrical heating coils embedded therein. |