摘要
The driving voltage and current signals of piezoceramic transducer (PZT) were measured directly by designing circuits from ultrasonic generator and using a data acquisition software system. The input impedance and power of PZT were investigated by using root mean square (RMS) calculation. The vibration driven by high frequency was tested by laser Doppler vibrometer (PSV-400-M2). And the thermosonic bonding features were observed by scanning electron microscope (JSM-6360LV). The results show that the input power of bonding is lower than that of no load. The input impedance of bonding is greater than that of no load. Nonlinear phase, plastic flow and expansion period, and strengthening bonding process are shown in the impedance and power curves. The ultrasonic power is in direct proportion to the vibration displacement driven by the power, and greater displacements driven by high power (>5 W) result in welding failure phenomena, such as crack, break, and peeling off in wedge bonding. For thermosonic flip chip bonding, the high power decreases position precision of bonding or results in slippage and rotation phenomena of bumps. To improve reliability and precision of thermosonic bonding, the low ultrasonic power (about 1-5 W) should be chosen.
The driving voltage and current signals of piezoceramic transducer （PZT） were measured directly by designing circuits from ultrasonic generator and using a data acquisition software system. The input impedance and power of PZT were investigated by using root mean square （RMS） calculation. The vibration driven by high frequency was tested by laser Doppler vibrometer （PSV-400-M2）. And the thermosonic bonding features were observed by scanning electron microscope （JSM-6360LV）. The results show that the input power of bonding is lower than that of no load. The input impedance of bonding is greater than that of no load. Nonlinear phase, plastic flow and expansion period, and strengthening bonding process are shown in the impedance and power curves. The ultrasonic power is in direct proportion to the vibration displacement driven by the power, and greater displacements driven by high power （〉5W） result in welding failure phenomena, such as crack, break, and peeling off in wedge bonding. For thermosonic flip chip bonding, the high power decreases position precision of bonding or results in slippage and rotation phenomena of bumps. To improve reliability and precision of thermosonic bonding, the low ultrasonic power （about 1-5 W） should be chosen.
基金
Project(50675227) supported by the National Natural Science Foundation of China
Project(07JJ3091) supported by Natural Science Foundation of Hunan Province, China
Project(2007001) supported by the State Key Laboratory of Digital Manufacturing Equipment and Technology
Project(2009CB724203) supported by the Major State Basic Research Development Program of China
关键词
超声波能量
阻抗
微电子学
实验研究
ultrasonic power
wedge bonding
thermosonic flip chip
input impedance
failure
