| 摘要 |
The invention, in its most basic form, is a sensor which detects sound generated by a laser ablation process. In a preferred embodiment of the invention, a conveyor system presents leadframe strips, having a fixed number of semiconductor packages which have not yet been singulated, to a laser marking apparatus. A dynamic microphone receives an analog input each time the laser marking apparatus makes a mark on a package. The analog input related to each mark is converted to a digital pulse. The series of pulses corresponding to the marking of packages on the leadframe strip are fed to a counter. The contents of the counter are compared with a preset number that corresponds to an expected number of pulses for the particular type of leadframe in use. The conveyor system is stopped so that the problem can be corrected if the expected number of pulses is not received by the counter, which indicates that one or more parts has not been properly marked. The invention may be applied to any operation requiring the marking of multiple sites on a single workpiece.
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