Papers by Author: Zhi Qiang Zhuang

Abstract: Both Al interconnects and flip-chip solder bumps were sensitive to high current. The failure mechanism of circuits interconnects would be more complicated if the current density in circuits was exceed the critical magnitudes of electromigration in both Al interconnects and solder bumps. The failure of circuit interconnects under different magnitudes of current density was studied and the interaction of electromigration in solder bumps and Al interconnects was discussed. The circuit interconnects of flip chip show three failure phenomena under high current density: voids in Al final metal, inter-diffusion of Al and SnPb, and melting of solder bumps. The voids in Al metal show the directional diffusion of Al atoms was mainly controlled by the electron wind fore. However the inter-diffusion of Al and SnPb demonstrated the electron wind force to Sn and Pb atoms would be ignored in contrast with chemical potential gradient or intrinsic stress. The flow of Sn and Pb atoms under high current density was in opposite direction with electron wind force and uniform with chemical potential gradient.

Abstract: Sb-doped BaPbO3 ceramics were prepared by sol-gel method. The influence of Pb/Ba ratio and Sb concentration on the electrical properties of BaPb1+x-ySbyO3 (x=0.0, 0.1, 0.2 and 0≤y≤0.2) compositions were investigated. Holes and Pb vacancies were the major defects in lightly donor-doped BaPbO3, where the increase of donor concentration resulted in decrease of charge carriers (holes), leading to resistivity increasing. In the highly donor-doped conditions, the microstructure or solid solubility substituted defect structure as the main factor affecting the variety of resistivity. The lowest electrical resistivity of Sb-doped BaPbO3 was 2.69 × 10-4 /·cm when the Sb concentration y=0.12~0.13. Excess of Pb causes the born of barium vacancies. And, the observed PTCR behavior of BaPb1.2O3 involves the Barium vacancies in grain boundaries. 0.5 mol% Sb-doped BaPbO3 showed the best PTCR behavior and its Curie temperature was about 850°C.

Abstract: The influences of the substitution of (Zn1/3Nb2/3) group for Ti as well as addition of Fe2O3 and K2CO3 on d33, kp, εr, and tgδ of the Pb[Zr0.46Ti0.54-x(Zn1/3Nb2/3)x]O3 + y mol%Fe2O3+z mol%K2CO3 (PZNPZT) (0 ≤ x ≤ 0.20, 0 ≤ y ≤ 0.10, 0 ≤ z ≤ 0.20) ceramics were investigated. The experimental results demonstrated that when x increases in Pb[Zr0.46Ti0.54-x(Zn1/3Nb2/3)x]O3+0.3 mol%Fe2O3+0.5mol%K2CO3 ceramics, the d33, kp, εr, and tgδ increase and approach to their maximum values, then eventually decrease. XRD analysis revealed that the perovskite structure of the materials transfers from tetragonal phase to rhombohedral phase. The relative dielectric constant (εr) decreases dramatically in the rhombohedral phase area near the MPB; the d33 and εr decrease with the small amount of added Fe2O3 and K2CO3, which also contributes to densification of the PZN-PZT ceramics. The optimized piezoelectric performances through the experiment were obtained as d33=280 pC/N, kp=0.62, εr=900, tgδ=0.003.