2004 Volume 47 Issue 3 Pages 287-293
In this paper, we describe an effective transmission method of high frequency ultrasound into a silicon chip via the polymer layers. The layer is inserted between water and the chip, and the pressure of about 0.1MPa is applied to the contact interface between the layer and the chip. The polyvinylidene chloride and polyvinyl chloride layers of 9µm thick bring the ultrasonic resonance between water and silicon, and the ultrasound in the frequency range of 20 to 80MHz is transmitted into the chip more effectively than the usual water immersion case. In practice, we carry out the acoustic imaging of the flip chip package via the layer, and clearly visualize the defective solder bumps beneath the chip under the dry-contact condition. Besides, the quality of the dry-contact image is equivalent to the water immersion image.