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Hakusan, Japan

Mohri M.,Nikko Company | Esashi M.,Tohoku University | Tanaka S.,Tohoku University
IEEJ Transactions on Sensors and Micromachines | Year: 2012

This paper describes a versatile and reliable wafer-level hermetic packaging technology using an anodically-bondable low temperature co-fired ceramic (LTCC) wafer, in which multi-layer electrical feedthroughs can be embedded. The LTCC wafer allows many kinds of micro electro mechanical systems (MEMS) to be more flexibly designed and more easily packaged. The hermeticity of vacuum-sealed cavities was confirmed after 3000 cycles of thermal shock (-40 °C × 30 min/ +125 °C × 30 min) by diaphragm method. To practically apply the LTCC wafer to a variety of MEMS, the electrical connection between MEMS on a Si wafer and feedthroughs in the LTCC should be established by a simple and reliable method. We have developed a new electrical connection methods; The electrical connection is established by porous Au bumps, which are a part of Au vias exposed in wet-etched cavities on the LTCC wafer. 100 % yield of both electrical connection and hermetic sealing was demonstrated. A thermal shock test up to 3000 cycles confirmed the reliability of this packaging technology. © 2012 The Institute of Electrical Engineers of Japan.


Tanaka S.,Tohoku University | Matsuzaki S.,Tohoku University | Mohri M.,Tohoku University | Okada A.,Tohoku University | And 2 more authors.
Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) | Year: 2011

This paper describes a versatile and reliable wafer-level hermetic packaging technology using an anodically-bondable low temperature cofired ceramic (LTCC) wafer, in which electrical feedthroughs and passive components can be embedded. The hermeticity of vacuum-sealed cavities was confirmed after 3000 cycles of heat shock (-40 °C/+150 °C, 30 min/30 min) by diaphragm method. The width of seal rings necessary for hermetic sealing of saw-diced chips is 0.1 mm or less. Electrical connection between MEMS on a Si wafer and feedthroughs in the LTCC wafer was established using Sn-containing met al stack simultaneously with anodic bonding. The developed wafer-level hermetic packaging technology is ready for practical applications.


Takano M.,Industrial Research Institute of Ishikawa | Takimoto M.,Nikko Company | Nakamura K.,Tokyo Institute of Technology
Acoustical Science and Technology | Year: 2011

To improve the controllability of ultrasonic linear motors in the longitudinal-bending mode, we have developed a multilayered transducer with independent electrode sets for the first longitudinal mode and the second bending mode. Since the vibration components are controlled independently by the transducer, it is possible to change only the driving vibration component with the component for friction control kept constant. The optimal shape and area of the electrodes in terms of efficiency were investigated analytically and experimentally. It was confirmed that an electrode shape in accordance with the mode strain contour gave a large output and that an optimum electrode area existed. The transducer with an optimal electrode pattern exhibited an efficiency improvement of approximately 10% and a 30% reduction of the temperature rise during motor operation. © 2011 The Acoustical Society of Japan.


Takano M.,Industrial Research Institute of Ishikawa | Hirosaki K.,Industrial Research Institute of Ishikawa | Takimoto M.,Nikko Company | Ichimura S.,SIGMA KOKI Co. | Nakamura K.,Tokyo Institute of Technology
Japanese Journal of Applied Physics | Year: 2011

Ultrasonic motors are nonlinear in input-output characteristics, which causes problems for precise control. To obtain good controllability and realize low-cost fabrication, we proposed an ultrasonic linear motor using a multilayered transducer with independent electrode sets for the first longitudinal mode and the second bending mode. We can change the shape of the vibration locus at the friction head arbitrarily by independently controlling the amplitude and phase of each vibration component. Controllability in the proposed motor was investigated by changing the shape of the vibration locus. In the proposed motor, the nonlinear part of the input-output characteristics is suppressed to 1/20 of that in conventional ultrasonic motors. As a result, a good positioning resolution of 20 nm and a low-speed drive of 0.1 mm/s were obtained with a simple closed-loop control system. © 2011 The Japan Society of Applied Physics.


Kamei T.,University of Miyazaki | Ahmed A.,Beni Suef University | Horai H.,Nikko Company | Ugai K.,Gunma University
Journal of Material Cycles and Waste Management | Year: 2015

This study investigates the development of solidification technology, based on the formation of ettringite, for fluorine-contaminated bassanite using waste and recycled materials. Recycled bassanite is mixed with coal ash, blast furnace slag and furnace cement type B in varying proportions to obtain the optimal ettringite production, based on the chemical response. Leaching tests are performed on the different admixtures to measure the solubility of fluorine. Scan electron microscope and X-ray diffraction tests are conducted on the samples to explore the formation and intensity of ettringite. The results show that the suggested admixture has a significant effect on the production of ettringite and increasing the cement content in the admixture increases the formation of ettringite. The increase of the ratio of cement in the admixture has a clear effect on the production of ettringite and the reduction of fluorine solubility compared to the case of cement–bassanite mixture. Both size and length of ettringite crystals increase with an increase in the ratio of cement-admixture/bassanite and intensity of ettringite in the material matrix. The solubility of fluorine decreases with the increase of admixture content because of the concomitant increase in the production of ettringite. The dimensions of the ettringite crystals have a significant effect on the reduction of the solubility of fluorine, i.e., an increase in ettringite prisms size decreases the fluorine solubility. The investigated limits of the suggested admixture do not show any adverse effect on the geo-environmental properties in terms of fluorine release. The suggested admixture is recommended as a stabiliser material for soft clay soil because it is environmentally friendly, economical and meets the environmental standards. © 2014, Springer Japan.

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