Wire Bonding Research And Design Of Variable Frequency Ultrasonic Generator

Frequency-modulated ultrasonic generator in chip package field was one kind of ultrasonic generator which was able to find different gold wire bonding transducer's resonant frequency automatically and make PLL intelligently in a large frequency range. The work was listed below:(1) Through the analysis, simulation and experiment of transducer's equivalent electronic model, electronic and resonant characteristic of transducer could be gotten. It offered definite theory basis of signal collected scheme and PLL arithmetic to the frequency-modulated ultrasonic generator.(2) Integrated design and each module's best scheme of frequency-modulated ultrasonic generator based on independent excitation have been discussed, which contained embedded controller, DDS signal generator, filter, power amplifier, signal collected system, signal process feedback system, human machine interface system and power supply.(3) For a ultra fast switch, low distortion, excellent stability and broad frequency spectrum signal source, DDS technique in the communication was introduced. Applying high speed AVR MCU to control DDS, system had the flexible, fast frequency-modulated ability. After DDS, there were anti thermal break down Hi-fi AB class power amplifier and precise designing filter which made the system be able to output excellent sine wave. At the same time, PLL circuit based on real RMS had brought in true power detector in RF field, which was able to transfer transducer's high crest current signal into DC voltage linearly and in linear-in-decibels form to the MCU fast and accurately. Judging the maximum and minimum digital number outputted by ADC, MCU was able to lock transduer's serial and parallel resonant status. Adding the phase detector circuit, the phase lock ability of the system was enhanced. Finally, suitable matrix keyboard, LCD, USB/RS232 computer communication and digital control of signal's amplitude and working time had been added in the product. (4) Experiments showed that frequency-modulated ultrasonic generator had the outstanding ability to drive transducer in a board frequency domain, to lock the resonant frequency in several resonant modes, to make PLL with high speed, and the functions of digital FM, AM, TM(time modulation), even impedance analysis.