Abstract
A direct measuring method for acoustic characteristics of thin-layered ultrasonic bonding materials is proposed. In this method, the knowledge of material constants such as density and velocity is not needed. The principle of the method is to measure the transmission and reflection wave intensity from the equivalent transmission lines composed of thin-layered bonding material which is sandwiched by fused quartz buffers. Then, by exciting one of the buffers with LiNbO_3 or ZnO film ultrasonic transducer, the transmission and reflection wave from bonding layer are measured. For different thicknesses of the bonding material, a series of measured data is obtained and the comparison of the data with theoretical curves determined the acoustic impedance and velocity of the bonding material. The ultrasonic attenuation constant of bonding material as a function of frequency is also determined by measuring the transmission and reflection wave intensity in the same manner as acoustic impedance measurement. The measuring method for rosin and stilben is described as an example and their acoustic characteristics are presented.
