Yasuo Hayakawa

Ultrasonic testing for flaw detection in ceramics

Abstract An advanced high frequency ultrasonic imaging system has been developed for detecting fine flaws in ceramics. This system consists of a computer for data and image processing, a high precision xyz-scanner with an immersion transducer, a high frequency (5–150 MHz) pulser, a receiver, and a peak detector. By using the imaging system with high frequency from 50 to 100 MHz, a 10-μm tungsten wire embedded 1·5 mm under the surface in SiC ceramic is detected. Some image processing techniques are used to enhance the ultrasonic image and detect fine flaws with low reflection echo levels.

ULTRASONIC IMAGING AND DATA PROCESSING TECHNIQUES FOR SEMICONDUCTOR AND NEW MATERIALS

Ultrasonic testing is one of the most useful NDT method for detection of fine flaws in the opaque materials. Recently, many applications of the ultrasonic techniques have been extended widely in the new field like electronics and advanced materials. This paper describes newly developed ultrasonic imaging system and its several applications in these areas.

Nondestructive Evaluation of Bonding and Delamination by Ultrasonic Testing.

Delamination in plastic-encapsulated integrated circuit packaging can lead to premature failure and also decrease heat resistivity. Therefore, development of nondestructive inspection of the bondind surface in a plastic package is an important subject for reliability improvement of integrated circuits. In this paper, delamination at the resin-chip interface which is measured using ultrasonic testing is discussed. At the delamination surface, the phase of reflected ultrasonic waves is reversed and at the bonding surface it is not. By using this phenomena, bonding and delamination can be discriminated. Delamination filled with water is also discussed. In this case, characteristic variation with frequency of ultrasound used is available for measurement of the gap thickness.