Abstract: In microelectronic packaging, wire bonding is the preferred method used to form electrical interconnections between integrated circuit chips and a substrate. However, ball lift (i.e., when a ball bond becomes completely detached from the chip) and wire breaking are critical problems that degrade the quality of a wire bond. In this study we considered three parameters of gold-ball bonding—ball bond thickness (7–22μm), gold-wire loop height (180–300μm), and gold-wire loop length (1050–2100μm)—and tried to determine the most suitable bond parameters to realize high-quality gold-ball bonding. For this, we experimented with four different values for each parameter considered. Ball shear and wire pull strength between chip and bond pad were used as parameters to evaluate the quality of the gold-ball bond. Experimental results revealed that the ball shear and wire pull initially increase with an increase in the gold-ball thickness up to 12μm and then starts decreasing gradually with further increases in the gold-ball thickness. Further, ball shear and wire pull between chip and bond pad were found to decrease with increasing gold-wire loop height and loop length. For achieving good-quality gold-ball bonding, a gold-ball thickness of about 12μm, and assuming that the cost of the gold consumed is a major concern, a gold-wire loop height of 180μm and loop length of 1050μm are suggested.
Abstract: A theoretical study of the performance of a CCHP system using natural gas as fuel which consists of gas turbine-steam turbine combined cycle, absorption refrigeration unit and exhaust heat boiler under variable loads was carried out. Two methods to adjust the electric and cooling loads are employed here. One method is to increase the outlet pressure of the steam turbine in the Rankine cycle. Another way is to change the air coefficient of the gas turbine. The calculation results show that the first method can obtain higher energy efficient and is the preferred method. The second way can be employed in case that further more cooling is required.
Abstract: The CCHP system based on energy cascade utilization can get very high energy overall utilization efficiency. When LNG is used as the primary energy of a CCHP system, the higher efficiency can be obtained if the cold energy of LNG is recovered. Three CCHP systems integrated with LNG cold recovery facility are presented which are suitable for different situations. The thermodynamic calculation and analysis of the system consisting of combined cycle generating electricity, the LiBr absorption refrigeration units, the cryogenic Rankine cycle generation system and the cooling medium system were carried out. The results showed that the energy utility efficiency of the electricity generating was 34.78% and the total energy utility efficiency was up to 86.49%. This indicates that this technology have the potential to be employed in the industrial applications.
Abstract: The type of beam-to-column connection in framework structure is determined beforehand in analyzing the frame structure using traditional design method. But it is not comprehensive and exact following that idea. It is difficultly to find the better and more proper design result such as the type of beam-to-column connection and the section of member in many viable design results. Therefore, a new design idea on steel frame -- the active semi-rigid connection design method is advanced in this paper. And some examples on the active semi-rigid connection design and the active semi-rigid connection optimal design are showed. From results, the type of semi-rigid connection makes an important effect on the mechanical behavior of the frame; it will cause the mechanical behavior of the frame to change obviously. And it will be got a better optimal result which considering more comprehensively in the whole frame view based on semi-rigid connection optimal design.
Abstract: UNESCO has put forward explicitly the concept of the eco-city in the "Man and the Biosphere Program (MBA)" for the first time. Over the past 30 years and more, all the countries in the world have established the eco-city as the goal of urban development. In the practice, some regions of China have also put forward the eco-city construction proposals; however, due to divergence of understanding of the eco-city theories and incorrect knowledge of the actual local conditions, there have been some misunderstandings in eco-city construction, resulting in the so-called “pseudo–ecology”. This essay is started from study of the basic theories of the eco-city. Based on analysis of the current conditions and problems, it probes into methods and measures of eco-city construction in China, with a view to promote the Chinese cities’ ecological development and eco-city construction.
Abstract: City roads are playing vital roles in the economic development. And both highway roadbeds take place geological disasters frequently. This article evaluates geological disasters with the method of AHP. The indexes include lithology, geological structure, slope, high slope, slope structure types, groundwater, slope size, rainfall, river erosion, slope back excavation, earthquake, etc. Through the analysis of the formation mechanism and impact factors in landslide, the model of landslide hazard assessment is established. Then landslide risk factors are partitioned into different levels, and seven part of geological disasters area are calculated. At last determine the risk level of landslide areas comparing with the risk classification table.
Abstract: At present, AC, a major gradation type of asphalt mixture, is widely used in highway construction in China. Due to internal large porosity, the water of road surface draining quickly, OGFC pavement is also widely used. However, water is easier flow into OGFC asphalt pavement than ordinary asphalt pavement. So the water stability of OGFC asphalt pavement is particular important. We get the following conclusion by the test of residual water and water stability based on the two gradations asphalt mixture of AC and OGFC. Residual water stays in AC asphalt mixture for about one week.While the residual water stays in OGFC asphalt mixture for more than three months. When the residual water is 50% in AC, the water stability is the worst. When the residual water is 75% in OGFC, the water stability is the worst.
Abstract: Based on numerical platform of large-scale finite element software, this paper investigates the function mechanisms of vertical load, horizontal load, and bending moment load of soft-clay-base bucket foundation. Then the corresponding load bearing characteristics of each load type of soft-clay-base bucket foundation are determined.
Abstract: This article argues the problem of ecological strategies in the landscape design and planning, and the main contents of ecological strategies. It includes the strategy of landscape sustainable development, which is in conflict with rapid economies and historic preservation, ecological conservation. The paper also discusses why people are the major controllable factor in the ecological strategies. In addition to these, the article studies the composition of landscape ecosystem, integrated ecology and design, integrated uses in landscape area, the method of interdisciplinary working. System theory is involved in this paper to discuss relevant questions.
Abstract: The altered rock type gold deposit is the one type gold deposits which can form super-large gold deposit. The super-large altered rock type gold deposit has its specialties among the forming time, forming generation, ore-hosted strata, wall rock alteration, area and structure. The southeast Guizhou Province has wonderful minerogenetic conditions. The area has the similar minerogenetic geological setting as many large, super-large altered rock type gold deposits. The characteristics of the altered rock type gold deposits that are distributed in this area have many similarities with other large, super-large altered rock gold deposits. It indicates that the deep of the southeast of Guizhou Province altered rock type gold metallogenic belt has great prospecting potentiality for looking for such type gold deposits from ore-hosted strata, ore-control structure, mineral paragenesis and ore-forming temperature etc.