ULTRASONIC EVALUATION OF SOLDERED CONNECTIONS BY MEANS OF A LEAKY LAMB WAVE DEVICE

An ultrasonic evaluation system of soldered connections which uses a leaky Lamb wave device operating at a liquid-solid interface is described. The leaky Lamb wave device has two arched interdigital transducers on a thin piezoelectric ceramic plate. The direction of the sound beam into water is varied considerably by changing the operation frequency because of the very dispersive property of the Lamb wave. This characteristic can be used effectively for C-mode imaging. Typical examples obtained by using a reflected wave from the back surface of the IC plate are successfully demonslrated.