| 摘要 |
1536872 Welding by pressure; connecting wires to components; spark erosion WELDING INSTITUTE 13 May 1976 [15 May 1975] 20701/75 Headings B3R B3V and B3A In thermocompression or, as shown, ultrasonic bonding the end of an aluminium or aluminium alloy wire to a component or terminal, e.g. in the wire connection of an IC silicon chip to a substrate circuit, by forming a ball on the wire end by spark discharge and thereafter positioning the ball on, and bonding it to, the component or terminal, the spark discharge is formed, in a gas shield, by applying a voltage not greater than 200 v (and preferably less than 50 v) between the wire end and an electrode (preferably carbon) and bringing the wire end and electrode into a temporary contact to fuse the wire end and break said contact, the resulting spark discharge forming the ball. The wire end may be of either polarity but is preferably negative with respect to the electrode. As shown, wire 1 extends from a reel 2 through a conductive clamp 3 and through a capillary nozzle 4 formed on a horn 5 of an ultrasonic welding transducer 6. The clamp 3, horn 5 and transducer 6 are mounted on a spring-biased lever 32 pivotable by a cam 30. The spark discharge electrode 9, is mounted in a holder 10 provided with a transparent hood 11 which is slotted at 15 to accept entry of the nozzle tip and wire. The holder 11 is mounted on an arm 12 pivotable by a cam 13. Shielding gas is supplied at 24 to flow through the holder 10 and out through the hood slot 15. The cams 30, 13 are driven by a common driving means 14. A capacitor 20, across a power supply 23, is connected, in series with a switch 21 and a variable resistance 22, between the clamp 3 and the electrode 9. A base 8 supports a microcircuit 7 to which the wire is to be bonded. In operation, after formation of the ball on the wire end with the cams in the positions shown the electrode 9 is withdrawn and the lever 32 is pivoted clockwise to bring the ball into contact with the microcircuit (Fig. 2, not shown). The transducer 6 is then energized to effect the ultrasonic bond. Subsequent bonding of the wire to an adjacent lead-out terminal (35) may be effected by wedge bonding, as by use of the nozzle 4. Reference has been directed by the Comptroller to Specification 1,341,259. |
