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.

Aluminum wire bonding was performed on a lab test-bed with PZT transducer device. Vibration behavior of bonder transducer was monitored, and the correlations between bonding pressure, high frequency tool vibrations, and average bond strength were then demonstrated to determine the statistically significant differences among them. Wavelet decomposing, combined with statistics-based data processing, was utilized to explore the details of bonding process and evade inherent bonding uncertainties. Experimental results show that the method is practical and effective even if the interactions between transducer and its bonding target are very small. The obtained time-frequency plots were depicted for identifying un-modeled wire bonding dynamics.

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.

This study seeks to quantify the screw-fastening effect of the tool/transducer on wire bonding performance. Aluminum wire bonding experiments were performed on a laboratory test bench. Characterizations of bonding process through a wavelet analysis were used to study the relation between screw fastening, vibration behaviors and bond strength. The time-frequency plots were depicted for identifying un-modeled wire bonding dynamics. Finally some statistically time domain features were presented for further analysis.