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The typical application of ultrasonic tomography is the determination of process parameters like component flow rates and material fractions in industrial environment. Another promising application is non-invasive health monitoring in medical care. Both acoustic attenuation and acoustic impedance inhomogeneity are the main physical quantities that are used to reconstruct the image. When transmission ultrasonic waves are shadowed by hard tissue because of severe attenuation, the reflection mode can be an effective supplement. This paper provides multi-objects reconstruction images by reflection ultrasonic tomography, demonstrating the multi-objects imaging capability of an immersion circular array system. The circular array consists of 36 ultrasonic transducers with 0.5MHz frequency which are ring arranged and embedded in the container wall to serve as both transmitter and receiver. Each time one transducer is fired and in the meantime other transducers are enabled to receive signals. Ultrasonic transmitting, propagating and receiving of the circular array system are simulated by COMSOL Multiphysics® software, after that a series of image reconstructions of the objects with different numbers are obtained through ellipse algorithm.

Thermo-mechanical failure is the main factor to impact the microelectronic packaging reliability. Under thermal loads, the microelectronic packaging is easy to produce cracks, delamination, voids, and other defects, which can emerge and grow under thermo-mechanical stresse caused by the different coefficients of thermal expansion (CTE). Firstly, a geometric model of Plastic Leaded Chip Carrier (PLCC) packaging was established and the thermo-mechanical property of PLCC packaging was analyzed using finite element analysis (FEA) software ANSYS. Then, the thermal cycling test on a set of PLCC packaging was conducted according to the MIL-STD-883H Microcircuits Test Method Standard with temperature range from-65°C to 150°C, and the crack growth rate of PLCC packaging was studied experimentally using Scanning Acoustic Microscopy (SAM). Finally, the Anand model was adopted to predict thermal fatigue life, which was consistent with the experimental results. With these researches, the thermo-mechanical reliability evaluation of the PLCC packaging was investigated using finite element analysis (FEA) combined with analytical methods.

The non-equilibrium statistical theory was used as a theoretical approach to modeling and predicting void evolution in metal materials. Fokker-Plank equation was introduced as the kinetic equation for the void evolution, from which the probability density distribution function of voids could be obtained. From the micro-mechanism of metal's irradiation damage, void growth rate equation was obtained using spherical Weilv model and control diffusion theory, and then was simplified based on appropriate assumptions. According to the probability density distribution function of void, a series of macro-mechanical characteristics caused by void growth can be calculated, such as: the critical radius of the void nucleation, the average radius of void. Thus the correlation between the void microstructure evolution and the macroscopic properties of metals can be achieved.

Scanning acoustic microscopy (SAM) is a powerful non-destructive testing tool used in electronic, material and medical testing area. Commercial SAM products are generally too expensive to be extended to common users. Therefore, a practical SAM system had been developed using high-frequency ultrasonic focus transducers, a wide-band pulse transmitter/receiver, a high-speed data acquisition card, and a high-precision motion system. The SAM　system's precision and function can meet the requirement of practical test adequately, and the cost is much lower compared to commercial products. Several kinds of imaging method were introduced, and the SAM system has the ability to accomplish full-wave data acquisition.