Development of a Millimeter-Wave Imaging Compact System & Contaceless and Quantitative Evaluation of Delamination and Crack with High Spatial Resolution

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1. Development of a compact imaging systemUsually, network analyzer is used as the equipment for microwave nondestructive testing. However, network analyzer has lager size and its price is high. Hence it becomes difficult to use it in the industrial environment. Therefore, a millimeter-wave compact equipment was developed to overcome these problems. Both the amplitude and the phase measurement can well be carried out by the compact equipment.2. Development of a millimeter-wave reflection focusing sensorA millimeter-wave focusing sensor utilizing two ellipsoidal reflectors woo developed for nondestructive evaluation of materials. By using the focusing sensor, liftoff distance between the sensor and sample woo effectively enlarged, while a higher spatial resolution was also obtained.3. Detection of defects and evaluation of electrical characteristics in electronic devices and thin films with high spatial resolutionThe delamination, which may occur between the chip pad and the encapsulate resin in IC packages, was inspected by millimeter-wave imaging technique. The full and part delamimations were successfully detected. Also a method for contactless measurement of the conductivity of thin conducting films, such us Indium Tin Oxide film, was developed. The measurement was successfully carried out by using the millimeter-wave compact equipment.4. Quantitative evaluation of closed small cracks on the metal surfaceA dual frequency technique was developed to evaluate the depth of small 2-D cracks of which situation regarding crack closure is unknown. On the other hand, a method to evaluate closure stress of cracks was developed. The effect of closure stress on the dual frequency technique was evaluated. In addition, to evaluate 3-D cracks, from the modified dual frequency equation, a new component named interference waveform was introduced, by which the shape and size of small 3-D cracks were successfully evaluated.