| 摘要 |
<p>1506164 Testing ultrasonic bonding operations MULLARD Ltd 20 May 1975 [9 July 1974] 30383/74 Heading G1G [Also in Division B3] An instrument for use with an ultrasonic bonding apparatus to estimate the bond strength operates on the principle that the strength is related to the change in vibration amplitude of the bonding tool as between when the tool vibrates freely and when the vibrations are modified by loading of the tool during bonding. A large change is indicative of a good bond. In the Fig. 3 embodiment a bonding tool (see Division B3) is vibrated by a pulsed magnetostrictive transducer 2 and the vibrations are sensed by a Piezo-electric transducer 8 fixed to 2. Signals from 8 are monitored at 16, amplified at Al and rectified at D. At the start of a transducer pulse, threshold circuit T triggers a delay circuit 24 which in turn operates sample and hold circuit 23 to sample the vibration amplitude at a selectable instant within the pulse. The gain of amplifier A2 is adjusted so that, with the tool vibrating freely (prior to bonding) the output voltage of A2 matches a reference voltage 25. During a subsequent pulse, when bonding is in progress, the sampled amplitude gives a difference signal output from amplifier A3. This signal is monitored at 26 and if it is less than a limit value set at 28 audible and lamp alarms 30, 31 are actuated by way of comparator A4 and relay 29. The procedure for setting up the limit value at 28 is described.</p> |
