Fabrication of electrical units

902,383. Semi-conductor devices. PHILCO CORPORATION. Sept. 19, 1958 [Sept. 20, 1957], No. 30045/58. Class 37. A metallic electrode 23 secured to a body of semi-conductive material is united to an external metallic member 10 by interposing between the electrode and the member a body 18 of fusible material including the metal of the electrode and heating the fusible body to a temperature at least equal to its melting point, but below that of the electrode, whilst maintaining the member, the fusible body and the electrode firmly in contact. The body 18 may be of a eutectic alloy. The part 11 of the member 10, which may be " tinned " with pure indium, is rapidly heated with the semi-conductor unit in position, the body 18 fuses and dissolves the metal of the electrode 23, whilst not melting it; and the arrangement shown in Fig. 2b results, apart from the attachment of the wire connector 30 to electrode 22, which attachment is accomplished by holding the wire in contact with the electrode and heating it rapidly. Apparatus for carrying out the method comprises a device 50, for holding the member 10 and provided with a cooling fluid via tube 54; a fluid-controlled, vertically movable electrical device 80 for rapidly heating the member 10; an arm 60 rotatable about a support 61 and provided with vacuum means 20 for holding the semi-conductor unit; and means 70, rotatable about a support 71, for holding the connector 30 and having electrical leads 78 to enable the connector to be heated. In the embodiment described, the semi-conductor body 21 is of germanium, the emitter electrode 22 of indium and gallium and the collector electrode 23 of indium. The body 18 is an indium-cadmium alloy pellet.