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We have developed and here propose a novel capacitive micromachined ultrasound transducer (CMUT) cell structure that has a long breakdown lifetime against high DC bias voltage. The structure extends the distance between the top and bottom electrodes by means of an additional insulating layer inserted at the cavity edge. The structure's electric breakdown voltage was increased by 1.2 times so that...
A highly reliable cell structure of capacitive micromachined ultrasound transducer (CMUT) was proposed. This structure equips with spacers (bumps) beneath the membrane and partial openings just above the respective spacers in the top electrode. The spacers prevent the membrane from direct contacting with the bottom surface of the cavity even when the total driving voltage exceeds collapse voltage...
In this paper, the authors propose an algorithm using branch and bound method to search an optimal replacement scheduling of obsolete equipment in aged primary substations. The developed tool can efficiently find an optimal solution from huge combinations of replacement schedules. The objective function to be minimized is the net present value of the sum of operation and maintenance cost, replacement...
A capacitive micromachined ultrasonic transducer (CMUT) was fabricated using a standard 0.25-mum CMOS backend-of-line process. By adopting the planarization of dielectric material between the upper and lower electrodes by chemical mechanical polishing (CMP), we achieved a time-dependent dielectric breakdown (TDDB) lifetime exceeding 10 years at a DC stress voltage of 192 V. In the case of DC and AC...
We successfully embedded this thin film capacitor in a conventional plastic-type build-up PKG substrate. The unique thin film capacitor consists of Perovskite-type ceramics sanded by metal electrodes, using thin film process technology. The total thickness is less than 1 um with extremely high permittivity, more than 1 uF/cm2.; the resulting PKG substrate shows short free including capacitor/electrode...
The progress of aging of transmission equipment is becoming a crucial issue in Japan, and adequate maintenance strategies need to be developed in order to use existing equipment efficiently. In this paper, we propose the concept of a life-cycle risk map (LCRM) which shows the transition of aging risk of equipment from its installation to replacement, under a specific maintenance strategy that consider...
We developed a thermal flying-height control (TFC) slider to control the flying height of magnetic recording heads. The slider basically consists of a small heater fabricated near the read/write element. This study discusses the effect of heater size and heater location on the change in the flying height at the read/write element. We also discuss the resulting temperature rise due to the additional...
The reliability of a stacked ball grid array (stacked BGA) package during the solder reflow process was examined using the finite element method (FEM). The stress intensity factors (SIFs) at an interfacial crack tip in the stacked BGA package were analyzed. Vapor pressure on the surfaces of an initial crack and thermal stress were considered. The vapor pressure during the solder reflow was estimated...
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