Patent GB-1483740-A (GB)
Title: Apparatus comprising means for controlling the movement of a tool
IPC: H01L21/00
Filed: 1974-11-15
Abstract: 1483740 Welding by pressure AUTOMATED EQUIPMENT CORP 15 Nov 1974 [5 March 1974] 49532/74 Heading B3R An apparatus comprises a base, a workpiece holder mounted on the base, a movable platform mounted on the base for X axis and Y axis movement under the control of a first control means, a support arm fixed on the platform, a tool holder coupled to the arm for Z axis movement and a second control means for controlling movement of a tool held by the tool holder independently of movement of the platform along the X and Y axes, the second control means including a driver mechanism, a driven mechanism coupled to the tool holder and a rotatable coupling mechanism with a plurality of positively coupled rotatable coupling members, a first of which is pivotally coupled to the driver mechanism and a second of which is pivotally coupled to the driven mechanism. An embodiment of an apparatus for thermocompression bonding wires to bonding pads on a transistor comprises a main base structure 21 which carries a support assembly 22, a micromanipulator 23 for moving the assembly 22, a wire bonding tool mechanism 24, a microscope 25 and an electronic control device 26. The assembly 22 supports a transistor strip indexing mechanism 27 including a heater unit and left and right hand transistor strip magazine holders 28, 29. The micromanipulator 23 comprises a handle 61 mounted in a spherical bearing in the structure 21 and is connected by a pin 64 with a linkage 66, 69, 75, 76 connected by spherical bearings 71, 73 to members 72, 74 fixed to the structure 21. The linkage is coupled to a pivot 79 carrying the inner ends of a pair of arms 82, 83, forming part of a pantograph, the outer ends of the arms 82, 83 carry spherical bearings 84, 85 coupled to manipulator links 86, 87 rotatably mounted on a shaft 88 secured to the structure 21. Extension arms 91, 92 of the links 86, 87 are pivoted to rings 93, 94 rotatable on a main spindle 44 forming part of the support assembly 22. A flange 45 on the spindle 44 rests on ball bearings 47 on the structure 21 and ring members 51, 52 inhibit rotation of the spindle 44 while permitting limited movement along X and Y directions. A spindle 41 rotatably mounted within the spindle 44 has a plate 40 on which is mounted the indexing mechanism 27. The tool mechanism 24 comprises a top frame 101 secured at the outer surface of its opposite sides 117, 118 to the top edges of two flat reeds 114, 115 which are coupled at their lower edges to the lower edges of two further flat reeds 107, 108 in turn secured by their top edges to support 103, 104 fixed to the structure 21. The lower edges of all four reeds are connected to move together. A mounting plate 102 is supported within the frame 101 by four flat reeds 107<SP>1</SP>, 108<SP>1</SP>, 114<SP>1</SP>, 115<SP>1</SP>, the reeds 114<SP>1</SP>, 115<SP>1</SP> being secured at their top edges to the plate 102 and connected at their lower edges to the lower edges of reeds 107<SP>1</SP>, 108<SP>1</SP> in turn secured at their upper edges to the inner surfaces of opposite sides 121, 122 of frame 101, the reeds 107<SP>1</SP>, 108<SP>1</SP>, 114<SP>1</SP>, 115<SP>1</SP> allowing the plate 102 to move relatively to the frame 101 in a direction at right angles to the direction of movement of the frame 101 allowed by the reeds 107, 108, 114, 115. A block 123 on the plate 102 carries an arm 131 which support a pair of reeds 132, 133 connected to a block 135 carrying a further pair of reeds 136, 137 fixed to a bonding tool holder fork 138. A tool holder 161 is fixed to the fork 138 to extend downwardly where a tip portion 162 carries a capillary tube forming the bonding head 163 through which wire 164 from a spool 165 is fed. A spiral spring 141 urges the fork 138 downwardly against a stop plate 139 while a spring urged push rod 146 acting through a bell crank 149 pivoted to the arm 131 and to the block 135 causes the holder fork 138 to assume a normal horizontal position. A wire clamp mechanism is provided on the block 135, a wire clamp 169 co-operating with a flexing clamp member 172 to clamp the wire just above the capillary tube 163. The clamp member 172 is operated by a solenoid 177. Cams 185, 186 and 187 on a shaft 188 are driven by a motor 181 to actuate arms 193, 194 and 195 respectively on a pin 196, the arm 193 being connected to the plate 102 by means of a slide member 204 positioned in a guide 205 secured to the plate 102, the arm 194 being similarly connected to the frame 101 and the arm 195 being pivotally connected to one end of a link 207. The other end of the link 207 is pivoted to one end of a drive arm 209 screwed to an upper coupling member 210 rotatably mounted on a bracket 212 fixed to the base of the apparatus. The end of the push rod 146 remote from the bell crank 149 is pivoted to a lower coupling member 215 rotatably mounted on the block 123 and between the upper and lower coupling members is an intermediate coupling member, the assembly forming an Oldham coupling. Thus the plate 102 and frame 101 may be moved in the X, Y directions without affecting the vertical position of the bonding tip 163 and rotation of upper coupling member 210 by arm 195 causes rotation of the lower coupling member 215 to move the push rod 146 and adjust the vertical position of the bonding tip. The motor 181 also drives a timing drum having optical sources 222 and photodetectors. In operation an operator places a transistor strip magazine holding ten strips on the left hand holder 28, the first strip is fed by the operator on to the indexing mechanism 27 which the operator then operates to bring the die 33, Fig. 3, of the first transistor unit under the capillary tip 163. The assembly 22 is then moved by the operator using the micromanipulator to bring the first bonding part of the die directly beneath the tip 163. The cams are driven to cause a first bond to be made at the pad 36 of the die 33 by causing the rod 146 to lower the capillary tube and bonding head 163 accompanied by flexing of the reeds 132, 133 and by flexing of reeds 136, 137 when the head engages the pad to cause the capillary tube to be moved to a position over the terminal 34 where a bond is made, followed by a short movement and a further bond made on the terminal 34. The clamp 164 is operated to break the wire and the capillary tube is moved to the pad 37. The wire is bonded to this pad and to the terminal 35 as before and the capillary tube returns to its initial position over pad 36. A new transistor unit is automatically positioned and the process repeated. Specification 1,439,958 is referred to.