The purpose of the present study is to supply the design guidelines of the high accuracy bonding process concerning the assembly of the semiconductor packages such as 2.5D, 3D and fan-out wafer level package. In this study, the target of the bonding accuracy of the die-attach process is within 3 μm. The authors fabricated the bonding unit consist of the transparent head and the sideview camera, which can directly recognize the alignment mark chucked on the bonding head. In order to solve the issue that the recognition accuracy becomes worse by the thermal fluctuation, the authors quantified the thermal-fluid behavior by the thermal fluid analysis and the particle image velocimetry, and clarified the correlation between the control factors of the recognition accuracy in the bonding process. Furthermore, the condition to reduce the thermal fluctuation was found, so that the bonding accuracy of ±3 μm was achieved in the die-attach process.

Recently, demand for the fan-out wafer level package is increasing because the market of IoT（Internet of Things）devices is expanding. Especially, higher accuracy and higher productivity are required for the chip-on-wafer bonding process. However, the process has the issue about the recognition accuracy caused by heat haze on the heated wafer. Therefore, the authors examined the quantification of thermal fluctuation behavior which fluctuates due to the temperature of wafer and jet flow by the thermo-fluid analysis. The bonder units such as bonding head, wafer and camera were modeled to clarify the thermal fluctuation behavior in the die bonder. The influence of the heated wafer and jet flow on the velocity and temperature of air was evaluated by the thermo-fluid analysis. Furthermore, the validity of the analysis was verified by the particle image velocimetry（PIV）.

Fusion welding degrades mechanical properties of the base metals such as strength and fracture toughness due to microstructure changes. On the other hand, application of friction stir processing（FSP）has been suggested to improve fatigue strength of several aluminum alloy or steel welds. It is known that FSP is an effective surface modification technique to refine and homogenize microstructure of various metallic materials in a solid state, based on the principle of friction stir welding. The microstructural modification in the welded zone using FSP can be also expected to enhance fracture toughness simultaneously. In this study, to investigate fracture toughness of a stir zone（SZ）produced by FSP at the surface of low-carbon steel welds, Charpy impact tests were carried out. FSP provided equiaxed ferrite grains in the SZ, and further grain refinement and cementite fragment were observed with decreasing FSP heat input. The upper shelf energy obtained in the TIG-welded specimens with FSP was much larger than those of the as-welded specimens. In addition, the SZ produced by low-heat-input FSP still remained ductile at -196℃ possible for significant plastic deformation. Thus, low-heat-input FSP could decrease ductile-brittle transition temperature due to significant grain refinement and cementite fragmentation. The results obtained in this study suggest the encouraging prospect of application of FSP as new post-weld treatment for improvement of fracture toughness as well as fatigue strength of the welded steel joints.

The manufacturing process of Bio-coke(BIC) is similar to that of Refuse Derived Fuel (RDF). The manufacturing processes mainly involve crushing, drying and solidification. Compared with RDF, BIC has higher specific gravity and maximum compressive strength, therefore it is superior in transportation, long-term storage, and safety. Therefore, in order to make BIC as biofuel from household waste RDF was crushed and BIC was constructed under various conditions of moisture and heating temperature. Then, compressive strength tests and combustion experiments were performed mass production of BIC from general waste was studied. As a result, it was found that BIC from general waste can be an alternative fuel for coal coke under the condition of a moisture content of 12% and a heating temperature of 140 ℃. Finally, group combustion velocity by general waste BIC was measured into real shaft furnace.