Fracture characterislics at the interface of ultrasonic bonds between Au and AI were characterized by SEM following pull lesting to effccl separation of the bonded joints. Vertical seclions at Ibe bonding point weir produced by ion-sputter thinning, alld were examined by TEM. Results show Ihat the Ibiekness of the Au/AI atomic diffusion intcrfacc was about 5O0mn due to combined effccts of ultrasonic and thennal energy. Ultrasonic vibration activates dislocations in tile crystallinc latliee and increases alomic diffusion. The fracture morphology on the lift off inlerface was dimpled rapture. Tensile fracture occurred during lbe pull test not al the bonded interface but in die base maleftal: the bond strength at the interlace was enbanced by the diffnsion reactions that occu~ed across the intert~cc due to tile combined ultrasonic and thermal energy

This paper presents a recent study by monitoring input power in wire bonding process on its performance. The instantaneous driving voltage and current to the PZT/transducer system were recorded and the input power histories for all tests were analyzed. A stable and satisfied bonding can be obtained at moderate ultrasonic power setting. A laser Doppler vibrometer was used to record the response of the structure. The initial power oscillating may represent the phase locking chaos, and the final attenuation may reflect the remains of kinetic energy in the structure. Strength of wire bonding should be attributed to the input power during the main loading segment.

利用基于关联维数的相位随机化的替代数据算法,对不同键合压力下超声换能系统中换能杆末端轴向振动的实测数据进行正确替代,并用非线性动力学的理论来检验其是否具有非线性。通过实验对所测振动时间序列的关联维数进行计算,结果表明在实际键合过程中,不同键合压力下变幅杆末端轴向振动都具有非线性成分。这有利于更好地认识超声引线键合换能系统,并为进一步利用非线性时间序列分析方法研究引线键合过程中的复杂振动提供了深入分析的科学手段。

The effect of the temperature on bondability and bonding process for wire bonding are investigated. Bondability is characterized by shear bonding strength and bonding process is represented by input and output power of ultrasonic transducer. A laser Doppler vibrometer and Labview software were used to record the velocity, voltage and current of transducer at different temperature settings. A K-type thermocouple sensor was used to measure the bonding temperature. Experimental results show that unsuccessful bonding happens at low temperature, and over bonding appears if the temperature is too high. Only when the temperature is at appropriate settings, can a stable and satisfied bondability be attained. The reason for this experimental observation is analyzed. By using a high resolution transmission electron microscope, the atom diffusion depth of Au-Ag bonding interface was measured and the result is about 200 nm. By using joint time-frequency analysis, the instantaneous characteristics of bonding process were observed completely and clearly. It is found that input and output ultrasonic power vs. time-frequency in a bonding process, including resonance frequency, harmonic components and amplitude of ultrasonic energy, vary along with the change of temperature settings.