GB929828A - Improvements in or relating to methods of soldering conductors to semi-conducting elements - Google Patents

Abstract

929,828. Semi-conductor devices. ELECTRIC & MUSICAL INDUSTRIES Ltd. Sept. 28, 1959 [Oct. 14, 1958], No. 32755/58. Class 37. A method of soldering a pair of conductors to a semi-conductive element comprises applying the conductors to the element with solder therebetween and passing an electric current through the element to beat it so as to melt the solder and provide a non-rectifying connection to each conductor. The solder may be applied to the semiconductive element or to the conductors or to both. The solder used may be a soft solder, e.g. eutectic solder with about 40% Sb, 60% Su, 2% Sb or 95% Su, 5% Sb or a hard brazing solder and may have a flux or fluxes e.g. ZuCl 2 in water or " Tricene " (Registered Trade Mark). In the drawing, 1 is a crystal of N-type germanium, Si, or indium arsenide exhibiting the Hall effect, current being passed in direction A between input conductors 3, 4, and current or voltage being derived in direction B by output conductors 8, 9, and a magnetic field applied by an electromagnet perpendicular to the plane of the drawing. The conductors may be strip, circular or plate conductors of tinned copper. The crystal 1 has layers of solder for 3, 4 and localised portions of solder for 8, 9 spaced from the layers of solder. Crystal 1 is mounted on support 2, 3, 4 are held taut and terminals 5 fixed in position and connected to the secondary of a transformer, or to a D.C. source. Connectors 6 which may be of insulating or conductive material are slidably mounted on fixed rod 7; they are moved away from each other to allow 1 to be mounted on 2 then moved towards each other to allow 3, 4 to engage the surfaces of 1 having the solder layers thereon. Current is now passed through 3, 4 to melt the solder and solder 3, 4, 8, 9 to 1. The decrease of resistivity of 1 with rising temperature can be used for automatically stopping the current to element 1 by operating a relay (when the current rises to a predetermined value). The device may operate as a voltage multiplier. To reduce the coupling between the magnetic field and conductors 8, 9, 8 or 9 may be formed as a double lead e.g. a hairpin, the apex being soldered to element 1 and each limb being bent to form a loop surrounding 1. Both 8, 9 may be hairpins. One limb of each hairpin can be severed near the apex. After the soldering all exposed areas are coated with an opaque insulating varnish.