Lead-free solders such as SnAg or SnAgCu is widely used for flip chip joining. As a result of higher melting temperature and higher elastic modulus of the lead-free solders compared to eutectic SnPb solder, defect of crack or damage in low-k dielectric layers under bond pad for flip chip joining in the semiconductor chip became a serious issue. The crack or damage is caused by mismatch of coefficient of thermal expansion (CTE) between chip and chip carrier substrate after chip join reflow. Various low melting temperature solders have been investigated and proposed as alternatives to SnAg or SnAgCu solders. Mechanical properties including creep properties are important factors as well as melting temperature for stress relief in micro joints and low-k layers. In this paper, the authors report measurement results of creep properties with fine-diameter-specimens (0.5 mm in diameter) of two low melting temperature solders (Sn-58Bi and In-3Ag) and conventional lead-free solder (Sn-3.0Ag-0.5Cu). The measurement matrix consists of four different strain rates and three different temperatures. The stress component n and the constant A in Norton's creep law were derived for each solder alloy. Then the stress analysis was performed with flip chip plastic ball grid array (FCPBGA) to evaluate stress at low-k dielectric layer under the bond pad using the obtained mechanical properties in this study.
A carbon fiber reinforced plastic [CFRP] is widely used for automobile, aircraft and so on, because of high strength, lightweight and weather resistance. The cutting of CFRP is difficult since it is composed of complex matrix of carbon fiber and epoxy resin. In this paper, CFRP was cut with a nanosecond laser of 1064 nm in wavelength. The ablation plume of CFRP was investigated by a high speed video camera and a spectrometer under the laser irradiation. From the results, it was clarified that the ablation dynamics differed with an increase in the laser shot number. It was confirmed that the ablation rate was 0.028 μg/pulse in good agreement with the calculation value of 0.03 μg/pulse.
A new type of circulating fluidized bed gasifier, which is called a fluidized bed gasifier with triple-beds and dual circulation, was proposed. Main features are the adoption of a triple-beds structure, the separation of circulation paths for tar-absorbing particle and fuel. Pyrolyzer and gasifier each have a two-stage fluidized bed. Tar can be treated in the gasifier. The two circulation systems each have an independent combustor. In this study, the fundamental gasification experiments were carried out using a small twostage fluidized bed gasifier. The amount of H2 formed during pyrolysis was markedly increased by tar cracking on porous alumina. Additionally, under steam gasification condition, H2 was also produced by steam reforming of coke. The heat balance calculations were carried out based on data of fundamental gasification experiments. The cold gas efficiency of our proposed gasifier is about 7% higher than that of typical dual fluidized bed gasifier. The particle circulation experiments were carried out by using a labolatoryscale cold model circulating fluidized beds. The particle circulation rate required for thermal independence operation was acquired. The gasification performance by bed material was evaluated. There is no big difference in the gas yields of porous alumina and limestone.
System is becoming large scale, complication, and diversification. Hence,an optimal product system design reflecting demands of society is required. To this problem, we built the system (named SDSI-Cubic). It creates optimization workflow order of the design process without any feedbacks based on the defined product system by SysML. However, the method of generating an optimization workflow automatically using DSM from SysML is not proposed. So, in this research, we propose the automatic generation method of the task DSM in consideration of optimization: new algorithm 1, by adding the dependency between design variables and objective functions to the conventional task DSM. Furthermore, we also propose the automatic method of generation an optimization workflow: new algorithm 2, by defining conversion rule from the partitioning result of this task DSM to an optimization workflow. And by performing automatic optimization of a cantilever using SDSI-Cubic incorporating these algorithms, we verified that it could optimize by using the algorithm to propose. As the future work, in order to solve a complicated problem efficiently, we need to consider the shortening method of optimization time by dividing an optimization problem.