ULTRASONIC SYSTEM FOR DETECTING DEFECTS IN IC PACKAGE USING LEAKY LAMB WAVE DEVICE

An ultrasonic technique is described for delecting defects that have occurred in an IC package, which uses a leaky Lamb wave device operating at a liquid-solid interface. An ultrasonic beam, radiated into water from an interdigital transducer for leaky Lamb waves, is incident on the sample surface in an oblique direction. The incident angle is an important factor for the ultrasonic beam to transmit in the sample. The direction of the sound beam in water is varied considerably by changing the operation frequency because of the very dispersive property of the Lamb wave. The system is demonstrated as one effective means for detecting defects in an IC package, and it can select the proper operation frequency and the radiation angle of the longitudinal wave