Conductive metal ball bonding with electrostatic discharge detection
View Patent ↗An apparatus for bonding a conductive lead to a conductive terminal of a device by the use of a conductive metal ball is disclosed. A ball-forming wire comprises a first conductive metal having a first melting temperature. A clamping surface has a closed position in contact with the ball-forming wire. A wire-clamping actuator is coupled to the clamping surface and is electrically connected to a clamping signal source. A sparking pin comprises a second conductive metal having a second melting temperature higher than the first melting temperature. The sparking pin is electrically connected to a power source. A current detection transformer includes a magnetic core at least partially encircling the ball-forming wire. An analyzing circuit is electrically connected to the current detection transformer.
1. An apparatus for bonding a conductive lead to a conductive terminal of a device by the use of a conductive metal ball, the apparatus comprising:
a ball-forming wire comprising a first conductive metal having a first melting temperature;
a clamping surface having a closed position in contact with the ball-forming wire;
a wire-clamping actuator coupled to the clamping surface and electrically connected to a clamping signal source;
a sparking pin comprising a second conductive metal having a second melting temperature higher than the first melting temperature, the sparking pin being electrically connected to a power source;
a current detection transformer including a magnetic core at least partially encircling the ball-forming wire; and
an analyzing circuit electrically connected to the current detection transformer, the analyzing circuit including an analog integrated circuit to broaden peaks in an output signal from the current detection transformer.
2. The apparatus of claim 1 further comprising a pin-translating actuator to which the sparking pin is attached, the pin-translating actuator having a sparking position in which the sparking pin is relatively closer to the ball-forming wire, and a non-sparking position in which the sparking pin is relatively farther away from the ball-forming wire.
3. The apparatus of claim 2 wherein an output of the analyzing circuit is responsive to the signal from the current detection transformer when the pin-translating actuator is in the non-sparking position.
4. The apparatus of claim 1 further comprising a wire actuator, the ball-forming wire passing through an aperture in the wire actuator, the wire actuator having a bonding position in which the distal end of the ball-forming wire is adjacent the conductive terminal of the device, and a tip-melting position in which the distal end of the ball-forming wire is not adjacent the conductive terminal of the device.
5. The apparatus of claim 4 wherein the aperture comprises a capillary tube.
6. The apparatus of claim 4 further comprising a vacuum source and wherein the capillary tube is in fluid communication with the vacuum source.
7. The apparatus of claim 1 wherein the device is a magnetic recording head transducer.
8. The apparatus of claim 1 wherein the first conductive metal comprises gold.
9. The apparatus of claim 1 wherein the first conductive metal comprises lead or tin.
10. The apparatus of claim 1 wherein the second conductive metal comprises tungsten or steel.
11. The apparatus of claim 1 wherein the wire-clamping actuator comprises a piezoelectric material.
12. The apparatus of claim 1 wherein the current detection transformer further includes a ferromagnetic core encircling the ball-forming wire.
13. The apparatus of claim 1 wherein the current detection transformer further includes a polyoxy-methylene thermoplastic doped with an electrically conductive additive selected from the group consisting of a non-carbon alloy, a carbon powder, and a carbon fiber.
14. The apparatus of claim 1 wherein the analyzing circuit further comprises an analog-to-digital converter to sample the broadened peaks.
15. The apparatus of claim 14 wherein a conventional PC sound card comprises the analog-to-digital converter.
16. The apparatus of claim 4 further comprising a display depicting an output signal of the analyzing circuit when the wire actuator is in the bonding position.
17. The apparatus of claim 16 wherein a digital oscilloscope comprises the display and the analyzing circuit.
18. The apparatus of claim 16 wherein the analyzing circuit includes an analog-to-digital converter to sample the broadened peaks, and wherein a conventional personal computer system comprises the display.
19. The apparatus of claim 1 further comprising a source of ultrasonic wave energy and an ultrasonic wave transmission path from the source of ultrasonic wave energy to the distal end of the ball-forming wire.
20. The apparatus of claim 1 further comprising a target actuator coupled to the device, the target actuator having a bonding position in which the distal end of the ball-forming wire is adjacent the conductive terminal of the device, and a queue position in which the distal end of the ball-forming wire is not adjacent the conductive terminal of the device.