Preload Affect The Regularity Of The Vibration Characteristics Of The Ultrasonic Transducer System

IC Packaging is the development foundation of all main industries, and is the key factor for developing other domains such as economy, safe guard and electronic products in our China. Nowadays, ultrasonic bonding, which including wire bonding and thermosonic flip chip bonding, are the main packaging processes for manufacturing semiconductor products. The transducer system is the key working actuator in bonder, and its characteristics of ultrasonic energy propagation and vibration in bonder, and its characteristics of ultrasonic energy propagation and vibration influence the bonding quality. The whole work is aimed for improving the bonding quality, in which the ultrasonic energy propagation in the system, the dynamic characteristics effected by pre-stress are discussed. This article through managing ANSYS simulation obtain the vibration mode of transducer system, and analyze the effect of transducer when the pre-tighten force is considered or not, and validate the result through finite element analysis with Impedance equipment. The study of this paper mainly bases on:1. The currently development and problem of the ultrasonic transducer. is dissertated in this paper, the nonlinear piezoelectric ceramic PZT-electrical coupling characteristics under compressive stress are described, the conformation changes of characteristic parameters in one-dimensional piezoelectric ceramics is the basis of the finite element analysis。 2. The theoretic model of ultrasonic energy propagation of transducer system is established based on equivalent method. The impedance/admittance model includes all parameters such as materials, size, frequency and load. Based on the model, the frequency and impedance of transducer system are calculated numerically, and the result are verified by experiments.3. The affection of pre-stress for the transducer back slab and mounting style is analyzed. The model analysis effected by the pre-stress between bonding tool and ultrasonic horn is constructed.4. Finite Element Harmonic analysis and Transient analysis are researched by changing the pre-stress between bonding tool and ultrasonic horn.5. Impedance test of transducer system is introduced in this paper, and the analysis result with Impedance equipment testing transducer system is validated. The ultrasonic energy of different directions for transducer system are attained by laser Doppler vibrometer.All above research contexts, methods and conclusions will help to understand, analyze and design the ultrasonic transducer in IC bonding.