Patent GB-1268059-A (GB)
Title: Improvements relating to apparatus for mounting semiconductor chips
IPC: B23Q39/04
Filed: 1969-03-24
Abstract: 1,268,059. Soldering. INTERNATIONAL BUSINESS MACHINES CORP. 24 March, 1969 [15 April, 1968], No. 15261/69. Heading B3R. [Also in Division H1] An apparatus for mounting a semi-conductor chip contact face upon a substrate comprises a chip placement tool adapted to receive a chip from a dispenser, a substrate table for receiving a substrate spaced a set distance from a tool in its working position gripping means movable relative to the table for frictionally engaging the substrate and means for moving the gripping means towards the tool more than the set distance so that the chip carried on the tool engages the substrate to move it with respect to the gripping means. This arrangement, shown in detail in Fig. 12A, forms part of the contact bonding apparatus shown generally in Figs. 1 and 3 which consists of a rotatable and raisable substrate holder 26 mounted on an XY table, a rotatably indexable table 39 carrying various tools which can be brought into position over the substrate and means for finely adjusting the XY position of the substrate holder manually. This latter comprises a template holder 38 and a stylus connected to the XY table via a pantograph arm 30 and linkage. The tools on the table (Fig. 3) consist of two fluxing tools 44, 56, a strap punch and placement tool 58 and chip placement tool 48. In operation, with the tools in the position illustrated tool 58 forms two straps for joining the base and emitter contacts of a transistor chip to lands on the substrate while the chip placement tool picks up a chip from bowl 308 and transfers it to a chip placement probe. The table is then indexed so that first the contact lands on the substrate are flux coated by tool 44, next the chip is placed on the substrate by tool 48, then the ball emitter and base contacts are coated with flux by tool 56, and finally the two straps are laid in position by tool 58. Operation of the individual parts of the system is as follows: Substrate holder.-Template holder 38 and substrate table S can be simultaneously rotated into one of four positions by Geneva mechanisms (not shown in detail) and when correctly positioned the stylus, corresponding to a tool, its manually adjusted to the desired position and its movement, reduced by the pantograph linkage, is transmitted to the X and Y plates 336, 334 (Fig. 12a) to bring the substrate table to the correct position. Compressed air is then admitted to cylinders 318 to raise turrets 17, carrying pairs of pins 76 urged against the substrate by springs 80, until the substrate meets the tool, whereupon it slips along the pins. On completion of the working operation the turrets are retracted so that the substrate comes into contact with table 324 to resume its original position. The process is repeated with the substrate under each tool. Fluxing tools (Fig. 10).-Each consists of a reservoir 324 with wells 249. Suitably arranged fluxing pens (250 as shown) are retracted from the fluxing position illustrated by operation of rotary solenoid 256 causing planet wheel 268 to run around on stationary sun wheel 270 thus rotating pen carrier 252 through 360 degrees to plunge the pens into wells 249. Chip placement tool (Fig. 11a).-Consists of contra-rotating vacuum probes 284, 292. At the position shown in Fig. 3 vacuum is fed to probe 284 to pick up a chip with its contacts down. A rotary solenoid 274 (Fig. 3) is then actuated to rotate the probes to the position shown in ghost where the chip is transferred by feeding vacuum to probe 292 and positive pressure to 284, probe 292 having mating recesses to accommodate the chip contacts. The probes are then returned to the initial position. Strap former (Figs. 4 and 6).-Consists of a frame 124 carrying a knife shaft 122 and vacuum probe shaft 132 rotatable by rotary solenoids through links 178, 154 respectively. Axially mounted on and slidably movable along the knife shaft are hammers 118, 120 with bolted on heads 228, 224. In operation strip metal is fed from reels 106, 112 on to tracks 110 with the aid of guides 111. Rotary solenoid 206 is actuated to rotate head 210 carrying diametrically opposed rollers 216, 218 thereby forcing apart pivoted arms 200, 202 engaging the hammers against the resistance of springs 126, 128. On actuation of solenoid 186 the hammer heads 224, 228 the construction of the faces of which is shown better in Fig. 9B, are brought into contact with the strip metal and punch dimples in it at 238. The hammer heads on being returned to the central position by the springs draw in the strip metal so that when knives 164, 166 are subsequently rotated the ends of the strips are severed and bent into recesses 240 in the heads. Then the strips are picked up by applying vacuum to probe 130 and rotating it through 90 degrees to the placement position and the hammers withdrawn.