| The ultra-sonic gold wire bonding technology is an interconnection technology to realize gold wire bonding for IC inner lead connection, which is achieved in the common role of ultra-sonic energy, temperature and bonding force etc. Bonding force is an important parameter in the bonding process, so the bonding force control becomes one of the key technologies for gold wire bonding. This paper has researched and designed a digital bonding force control system, with the discussion of the principal and methods, also the experiment for system test.The design of the digital bonding force control system includes two main parts:the hardware and the software design. By designing and simulating each modules respectively for both hardware and software, the system can be integtated and validated at last.The hardware design includes:power module, DAC module, driver module, bonding force sensing module, dispaly module and host PC communication module.The software design includes MCU software and PC software design, where MCU software is composed of bonding force control module, bonding time control module, ADC module, serial port communication module and display module; and PC software consists of the serial communication software which is developed based on VC++MFC, to realize the interactive between MCU and PC, such as setting the bonding force and bonding time.As for the control algorithm of the system, this paper adopts the fuzzy PID adaptive control algorithm to achieve bonding force control which simplifies the hardware and gets better performance. Parameter tunning is critical for digital PID algorithm. In this paper, the KP、KI and KD are tuned to the best by experiment after simulation. The mathematics modle is established and simulated with the fuzzy PID adaptive control algorithm to gain the PID input-output and the three parameter response curves.The bonding force control system is aimed to provide stable bonding force. So in the experiment testing part, the bonding force measuring is firstly done with the designed bonding force sensing module. The measured data is then feeded back to MCU to realized closed-loop control. Afterward, from the comparison of the digital input signal and the respondent force output signal, the control performance of the system can be evaluated. Lastly, by measuring the corresponding force under different digital input, and drawing the relationship between them, the further conclusion can be made that the system can drive stable bonding force. |
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