Bond Wire Lift-off Sensor Circuit for Power Devices Integrated in Gate Driver IC

To achieve low-cost detection of bond wire lift-off for power devices without sensor circuits made of discrete components on PCB, the world’s first fully integrated bond wire lift-off sensor (BWLS) compatible with existing gate driver IC is proposed. When several bond wires in the emitter of an IGBT lift off, the increased parasitic inductance leads to a higher induced voltage, which raises the transient-state turn-on gate-to-emitter voltage (V
GE
). The proposed BWLS detects bond wire lift-off by tracking and holding the variating transient-state turn-on V
GE
. The BWLS is designed to automatically find the optimal capturing timing because the maximum sensitivity is achieved if the V
GE
is held when collector current varies the most. For function verification, a gate driver IC with integrated BWLS is fabricated with 180 nm BCD process. Double pulse test results at 20 A and 80 A show that the proposed circuit successfully detects the reduction in the number of bond wires from the initial value of six to one in an IGBT module and achieves an average sensitivity of 54 mV per wire.