LEAD WIRE BOND ATTEMPT DETECTION
 Inventors: John A. Kurtz, Gorham; Donald E.
Cousens, Saco; Mark D. Dufour,
Portland, all of Me.
 Assignee: Fairchild Camera & Instrument
Corporation, Mountain View, Calif.
 Appl. No.: 470,217
 Filed: Feb. 28, 1983
 Int.Cl.+ H01L 21/90
 U.S. CI 228/104; 219/56.21;
 Field of Search 228/104, 4.5;
 References Cited
U.S. PATENT DOCUMENTS
4,098,447 7/1978 Edson et al 228/4.5
4,213,556 7/1980 Persson et al 228/104
4,419,562 12/1983 Jon et al 228/104 X
4,441,248 4/1984 Sherman et al 228/104 X
Primary Examiner—Kenneth J. Ramsey
Attorney, Agent, or Firm—Kenneth Olsen; Carl L.
Silverman; Daniel H. Kane, Jr.
A method and circuits are described for sensing and detecting bond attempts and weld attempts during bonding and welding of lead wire. The method and
circuitry are particularly applicable for detecting missed ball bonds and missed wedge bonds during bonding of lead wire between the die pad of a microcircuit chip and the lead frame on which the chip is mounted. A sensor (30) or sensing circuit (42) senses the different characteristic electrical condition of the lead wire (11) following a ball bond attempt and following a wedge bond attempt. A bond attempt indicator (45) indicates high resistance in the lead wire following a missed ball bond while weld attempt indicator (46) indicates low resistance in the lead wire (11) following a missed wedge bond. The lead wire (11) is isolated from uncontrolled contacts with ground potential while the lead wire is held in the bonding tool and bonding machine. Switching circuit (38) electrically switches and couples the lead wire to a controlled ground coupling (27), (52) during ball formation or to a ground isolating voltage source (28), (54) for delivering current to the lead wire and establishing a bond sensing and detecting mode following the ball bonding operating mode and wedge bonding operating mode of the bonding machine. The switching circuit (38) is actuated by a control signal (40) from the control signal circuitry of the bonding machine or from independent control circuitry. Time sequence circuitry may also be provided for the control signals.