键合力对超声键合换能系统振动影响的时频分析

Time-Frequency Analysis of Effects of Bonding Pressure on Ultrasonic Vibration

在超声引线键合过程中,键合力是影响键合强度的重要因素之一。通过实验研究了键合强度与键合力之间的关系。在不同键合力情况下,通过小波分解的方式对速度信号进行分析,得出在键合力不同的情况下键合机超声速度信号的时频特性。分析发现,只有在键合力适中的情况下,键合强度才能达到最大,速度信号中的不稳定成分主要来自于劈刀与基板的接触表面,随着键合力的升高,速度信号逐渐稳定,阶跃信号即不稳定成分逐渐减小,有效地提高了信号能量的传递比率。

In ultrasonic wire bonding process, the bonding pressure is one of the most important factors to the bonding strength. Thepaper analyzed the relations between the bonding pressure and the bonding strength through the experiments. With different situations of bonding pressure, the velocity was analyzed with the tools of wavelet. The time-frequency characteristics of ultrasonic velocity were obtained under different situations of the bonding pressure. The analysis discovers that, only when the bonding pressure is in a moderate conditions, the largest bonding strength can be reached, the unstable ingredient in velocity signals mainly comes from the laying surface of the capillary and the work-older, as the increase of the bonding pressure, velocity signals become stable gradually, the step signal （the unstable ingredient） gradually reduces, the signal energy transmission ratio is enhanced effectively.