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Previous chapters of this book have discussed the wetting behavior of near-eutectic Sn-Pb solders. These alloys are the most common in electronic applications and are deserving of the greatest attention. However, there are many applications where the properties of these alloys can be improved. A composite solder, or a solder that contains second-phase dispersions of particles, could improve solder joint properties. The area where composite solders could have the greatest impact is in improving the mechanical properties of the joint. However, the wetting behavior of the solder cannot be compromised for the sake of the mechanical properties -good wetting behavior is a necessity. Therefore, for a composite solder to be useful for electronic packaging applications mechanical properties, wetting and manufacturability must be optimized.

In the acousto-ultrasonic technique, a wave is injected onto the surface at one location and the displacement normal to the same surface is measured at another location. Thus, understanding the propagation characteristics of the wave is essential for successful application of the technique. The main objective of the present investigation is to identify through analysis-experiment correlation how the AU wave propagates through composite laminates.