Development of a Nondestructive Visualization Technique
Using the Dry-Contact Ultrasound
Needless to say, IC packages are the key components of all modern electronic products, and the nondestructive evaluation of defects in packages is indispensable for ensuring the reliability and the quality of electronic products. The ultrasonic technique has widely been used for visualizing the defects in packages, but the usual ultrasonic technique requires the immersion of the packages in the coupling liquid such as water. To overcome the inherent problems of the usual ultrasonic technique, a new technique for effectively transmitting high frequency ultrasound under a dry-contact condition has been developed. The present technique performs the transduction of ultrasound via a thin solid layer inserted between the coupling liquid and the package, and the atmospheric pressure of about 0.1 MPa is applied to the layer/package interface. Based on the dry-contact technique, we have developed a dry-contact scanning acoustic microscope, and already realized high-resolution acoustic imaging of package without getting it wet (Fig. 2).
Using the Dry-Contact Ultrasound
Fig.2 Visualization of BGA solder joints.
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