Patent GB-933248-A (GB)
Title: Fine wire manipulator and bonding instrument for transistors
IPC: H01L21/00
Filed: 1961-07-05
Abstract: 933,248. Semi-conductor devices. KULICKE & SOFFA MANUFACTURING CO. July 5, 1961 [July 5, 1960], No. 24339/61. Class 37. A manipulator in a fine wire-bonding instrument comprises a frame carrying a horizontallyslidable plate with an aperture through which passes a rod, the upper end of which is swiveljointed to the frame. Movement of the lower end of the rod thus transmits proportionally reduced movement to the plate. Fig. 1 shows the general arrangement in which a wire dispenser unit C is first positioned accurately in X, Y and Z directions by means of a slidable pad 114a and lever 152a, with respect to a transistor unit held in a holding and heating element 40, and then a bonding pressure needle 180 is similarly positioned over the wire by means of slidable pad 114 and lever 152. The transistor header 190 (Fig. 17), rests on a slidable support tube 51 (Fig. 3), which is spring-urged upwards but may be depressed by means of lever 64 (Fig. 1), to allow insertion of a transistor unit into holder 40. Tube 51 and holder 40 can be manually adjusted to a suitable axial position in the horizontal plane by means of slider 30 which is movable in a hub member 22 which is rotatably mounted on the frame 12. The mechanism for moving the pressure needle unit E is shown in Figs. 1 and 7. X- axis slider 80 is ball-bearing mounted on guide member 74 which is fixed to frame 12, and Y-axis slider 92 is ball-bearing mounted on X-axis slider 80. Slider 92, which may thus move in both X and Y directions is controlled by lever 110, which is ball-jointed at 108 to the frame and engages slider 92 by means of slidable ball-joint 112. Lever 110 is set into any position by sliding friction pad 114 over surface 116 on frame 12 thus controlling small movements of slider 92 in both X and Y directions. Movement in the Z direction is controlled by lever 152 which rotates cam 144 pivoted on a plate 122 fixed to slider 92 to engage cam surface 148 thus depressing Z-axis slider 128 which is ball-bearing mounted on plate 122. The bonding pressure needle 180 is mounted on an arm 176 which is pivoted in unit E which is mounted on slider 128. The arrangement is such that when pressure from an engaging surface first lifts needle 180 it exerts a pressure of 4-10 grams and then on rising further so that arm 176 engages a further lever 186, the pressure rises to 80 grams. Springs are used to bias all the sliding elements to one position to avoid lost motion. The wire dispensing unit C is positioned along X, Y and Z axes by a lever and control arrangement similar to that described for the needle unit E. The unit C comprises a wheel supporting a plurality of circumferential wireholding tubes; each tube holds a length of fine wire which may have a jacket of nickel or silver to facilitate handling. Fig. 17 shows a gold or silver stripe electrode 201 on the semi-conductor wafer being connetted by the fine wire to the end of a transistor lead 196. When the transistor header is suitably positioned in holder 40, the wire dispenser C is moved by means of pad 114a to position the wire over the metallic stripe 201 while viewing through microscope 18. Needle 180 is then positioned by means of pad 114 and brought down to exert a pressure of 4-10 gms. on the wire while the heater in holder 40 is operative to effect thermo-compression bonding at 580‹ C. A gas tube in holder 45 is used to provide a hydrogennitrogen atmosphere for this operation. The operation is then repeated to bond the wire to the end of lead 196 now utilizing the higher pressure of 80 grams which also acts to seal off the wire by a scrubbing action. Electrode stripe 200 is then connected to lead 195 in a similar manner. A thermo-couple is provided in holder 40 for temperature measurement.