Papers by Keyword: Bump

Abstract: 4H-SiC homo-epitaxial film was grown by adding HCl gas with a high Cl/Si ratio in CVD process, and defect formation and origin of the defect were investigated by confocal differential interference contrast (CDIC) microscope, PL imaging and normal differential interference contrast (DIC) microscope. It was found that a large number of large bumps are formed on the film grown at a high Cl/Si ratio of 30, and a large number of PL defects on bare substrate before the film growth are also observed. Coordinates where the bumps on the film are observed were good agreement with those where the PL defects on the bare substrate are observed. An etch pit sample on reproduced substrate from which epitaxial film was removed was fabricated by etching process using molten KOH+Na₂O₂, and some types of etch pits which might be originated from threading edge dislocations (TEDs), threading screw dislocations (TSDs) and basal plane dislocations (BPDs) in the substrate were observed. The coordinates where the etch pits on the reproduced substrate are observed were also good agreement with those where the bumps on the epitaxial film are observed. Therefore, it was clarified that a large number of the bumps abnormally grown on the epitaxial film are originated from the dislocations in the substrate.

Abstract: The paper studies the behavior of a quarter-car suspension model under periodic road excitation: sinusoidal and bump (trapezoidal shape) for a constant vehicle speed. A theoretical and a finite element model were developed. The theoretical model has two degrees of freedom and a modal and sinusoidal excitation was performed to compare with finite model analysis. The finite element analysis consists of three parts: preload, modal analysis and deterministic external excitation. The study consists of the analysis of forces, displacements and accelerations that are transmitted to the vehicle regarding their variation in time and frequency.

Abstract: Under the background of information age, the computer plays a dominant role, and especially the emergence of the network makes the parallel computing possible. It makes the computer do a lot of image information processing in a short period of time, so as to obtain the best effect of art image design. Based on this principle, we design the model and algorithm of art image design through computer. We use normal bump of texture image processing technology, transforming two-dimensional image to 3D display, so as to achieve a good effect of art show. Finally, based on the construction of city public environmental art and city image, using the public environmental logo design as an example, we study the three-dimensional effect in identification system, so as to get a good image of the city, and provide a theoretical reference for the study of city public art and the image of the city.

Abstract: An experimental analysis of the influence of the bumps on the surface forces in micro gap plates is presented. Because of extremely small sizes of micromechanical structures in MEMS, surface forces between micromechanical components may become significant to influence behaviors of microelectromechanical devices. The bumps are important in micro structures as they change the adhesion condition of the plates, and will influence the surface forces in micro gap plates greatly. To identify relative importance of surface forces with bumps, the experimental instrument which consists of the V-shaped electrothermal microactuator, the suspended plate and the flexible beam is designed. The displacements of the suspended plate with different bumps are measured by experiments, and the surface forces are got by calculation. By analysis, it could be found that the surface force increases with the increasing drive voltage and the increasing normal voltage, and the surface force gets the minimum when the number of the bumps is 9.

Abstract: For flip-chip process of RF system-on-packages(SOP), double bump bonding processes were investigated. Sn-Ag and Sn solder joints were formed by the reflowed double bumping process, and Sn/In/Sn bump joints were fabricated by the non-reflowed double bump bonding process. The height-to-size ratios of 0.78 and 0.65 were obtained for the reflowed double bumping and the non-reflowed bumping, respectively. Average contact resistance of the reflowed Sn-Ag and Sn solder joints was about 13m/ which was much lower than 24~33m/ of the non-reflowed Sn/In/Sn bump joints. The reflowed solder double bumping method is more suitable for flip-chip process of RF-SOP than the non-reflowed double bump bonding.