Patent GB-939762-A (GB)
Title: Method and apparatus for assembling a semi-conductor device
IPC: H01L21/60
Filed: 1960-12-12
Abstract: 939,762. Semi-conductor devices. CLEVITE CORPORATION. Dec. 12, 1960 [Dec. 18, 1959], No. 42633/60. Class 37. A semi-conductor device is assembled by accurately positioning a first sub-assembly in a heater means, positioning a second subassembly close to the first sub-assembly and fine adjustment means to index the two subassemblies into contact and to continue movement for a predetermined period after initial contact to establish a predetermined pressure between the assemblies whereupon a current is passed between the conductive element of the assemblies and the heater is energized to fuse the two assemblies together. The semi-conductor device consists of a first sub-assembly 15 (Fig. 1) comprising a semi-conductor wafer 19 in a glass tube or cup 16 with lead wire 17 and a second sub-assembly 20 (Fig. 2) consisting of a gold whisker 23 attached to lead wire 22 with glass bead 21 which is to be sealed inside the tube 16 to form a diode. The apparatus comprises a rotatable turret 25 (Fig. 3) with a plurality of holders 26. At the first workstation 30 a sub-assembly 15 slides down track 60 (Fig. 5) into position in holder 26 so that glass portion 16 lies inside a heater coil 33 and lead wire 17 rests against a magnetic stop 62. Cam operated jaws 50 and 49 then close to grip tube 16 and wire 17 respectively and the turret rotates so that the holder 26 arrives at the second work station 31. Here jaw 50 is slightly relaxed and cam operated arm 32 (Fig. 6, not shown) pushes sub-assembly 15 into coil 33 to a precise depth determined by the engagement of arm 32 with the top of coil 33; jaw 50 then restores to clamp element 15. At the third work station 35, a sub-assembly element 20 from shoot 80 is picked up by a magnet 90 (Fig. 7) on a transfer arm 91 which is pivotally mounted at 92 on to a reciprocating member 93. As member 93 moves to the right, wheel 94 on arm 91 bears on cam surface 96 so that arm 91 rotates to present element 20 in inverted position against magnet 41 on member 42. To ensure satisfactory " snap over " action, the arrangement is such that wheel 94 is held slightly away from cam surface 96 at the extreme bottom position by pivot 92 on member 93. While the turret 25 moves towards the fourth work station 40, a cam mechanism moves member 42 and therefore element 20 towards element 15 so that whisker 23 approaches wafer 19. At station 40 a fine control unit 100 comprising a micrometer screw device 101 is operated and this is arranged to press down on member 42; movement of the device 101 is effected by electric motors and gearing and controlled by advance and reverse clutches and a braking mechanism. As member 42 is forced downwards whisker 23 engages wafer 19 which completes an electric circuit to operate a timer. At the end of a predetermined time interval movement of fine control device 101 is stopped thereby establishing a prearranged pressure between the whisker and the wafer, an electric current pulse is passed through the whisker and wafer to weld these together, and the heater coil 33 is energized to weld the glass bead 21 to glass tube 16 and complete construction of the diode. The completed diodes are automatically released from each work-holder 26 after the table has rotated a further amount. Specifications 939,763 and 939,674 are referred to.