Papers by Author: Osamu Kamiya

Abstract: The low-cycle fatigue behavior and the relationship between the surface features in the low-cycle fatigue testing and the fatigue life of Sn-3.5Ag and Sn-0.7Cu lead-free solders were investigated at strain rate of 0.1%/s at room temperature, 80 and 120oC. In addition, the fatigue life was estimated by using the surface deformation of the solders, and image processing. And also, it was compared with Coffin-Manson type of fatigue behavior. The fatigue life of Sn-3.5Ag solder was superior to that of Sn-0.7Cu solder at temperatures, 80 and 120oC. The fatigue life determined by surface deformation indicated a close behavior to Coffin-Manson type fatigue behavior in those solders. Therefore the low-cycle fatigue life of solders could be estimated by the surface deformation.

Abstract: The low-cycle fatigue behavior on Sn-0.7Cu lead-free solder as-cast and Sn-Pb eutectic solder as-cast were investigated at a strain rate 0.1%/s under various temperatures of 25, 80 and 120oC. In addition, the relationships between the surface feature in the low-cycle fatigue test and low-cycle fatigue life of those solders at 25oC were investigated by image processing. The low-cycle fatigue life of Sn-0.7Cu decreased when the temperature increased. And the fatigue life of Sn-0.7Cu was better than that of the Sn-Pb eutectic solder at the temperatures of 25 and 80oC. The low-cycle fatigue behavior on the solders investigated followed Coffin-Manson equation. The fatigue ductility coefficient of Sn-0.7Cu was found to be affected by the temperature. The surface deformation as fine meshes in the low-cycle fatigue test of Sn-0.7Cu did not appear until 10% of the fatigue life. Although it was over 10% of the fatigue life, the surface deformation that was caused by micro cracks and coalesces occurred with the increasing number of cycles. The relationships between the surface feature in the low-cycle fatigue test and the low-cycle fatigue life on Sn-0.7Cu and Sn-37Pb solders were discussed.

Abstract: The effect of the surface properties on the microtribological characteristics of AlN-based electrostatic chuck (EC) for silicon plasma etching was investigated using automatic microscratch testing technique in combination with SEM examination of the scratch track. The scratch testing was performed by applying a progressive indenter load. The scratch failure model varied systematically with the surface properties of AlN. The data of the onset of brittle fracture were used as characteristic features of the AlN failure. It was found that the critical load, Lc, the smallest applied normal load leading to unacceptable damage such as chipping and cracking, increases with decreasing the average grain size, density and fracture toughness of AlN and decreases with increasing the surface roughness and area density of pre-existing polishing damages. The resistance to cohesion and adhesion failure of AlN with 0.1 µm Al2O3 oxide layer on top was stronger than that of the AlN bulk material. The fracture initiation and ductile to brittle transition in AlNAl2O3( 0.1µm) was in form of discontinuous chipping. The results infer the potential of the combination of the scratch data with the material properties for the understanding of the effect of the surface topography on the mechanical properties and chucking performance of AlN-based EC.

Abstract: A microtibological study of the effect of the CMP machining surface damages (SD) on the micromechanical properties of AlN electro-static chuck (ESC) for silicon plasma etching is presented. AFM and SEM examinations of the AlN ESC, which were CMP finished to a surface roughness, Ra = 20 nm, have revealed machining geometry errors and chemical mechanical SD caused by the CMP slurry. The elastic modulus (E) and hardness (H) of AlN and those of yttrium (Y) particles were discretely clarified using localized nanoindentation technique. The results showed that the CMP machining SD fatally affected the AlN/Y boundary strength and resulted to errors in the first contact points between the indenter and the sample. In addition to SD, the micro scale viscoelasticity phenomena of AlN in indentation caused peculiarities at peak loads in the load vs. depth plots. Under these circumstances, the values of E and H measured using Oliver and Pharr's method are in fact underestimated; E = 400 GPa and H = 20 GPa for AlN particles, 300 GPa and 17 GPa for Y particles and 500 GPa and 16 GPa for AlN/Y interface, respectively.