This study proposed a noble process to fabricate TSV (Through Silicon Via) structure which has lower cost, shorter production time, and more simple fabrication process than plating method. In order to produce the via holes, the Si wafer was etched by a DRIE (Deep Reactive Ion Etching) process. The via hole was 100 m in diameter and 400 m in depth. A dielectric layer of SiO 2 was formed by thermal oxidation on the front side wafer and via hole side wall. An adhesion layer of Ti and a seed layer of Au were deposited. Soldering process was applied to fill the via holes with solder paste and metal powder. When the solder paste was used as via hole metal line, sintering state and electrical properties were excellent. However, electrical connection was poor due to occurrence of many voids. In the case of metal powder, voids were reduced but sintering state and electrical properties were bad. We tried the via hole filling process by using mixing solder paste and metal powder. As a consequence, it was confirmed that mixing rate of solder paste (4) : metal powder (3) was excellent electrical characteristics. Received : Dec. 7, 2012, Accepted : Mar. 7, 2013 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/licenses/bync/3.0)which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
In this paper, we developed a beam of MEMS probe card using a BeCu sheet. Silicon wafer thickness of 400 m was fabricated by using deep reactive ion etching (RIE) process. After forming through silicon via (TSV), the silicon wafer was bonded with BeCu sheet by soldering process. We made BeCu beam stress-free owing to removing internal stress by using joule heating. BeCu beam was fused by using joule heating caused by high current. The fabricated BeCu beam measured length of 1.75 mm and width of 0.44 mm, and thickness of 15 m. We measured fusing current as a function of the cutting planes. Maximum current was 5.98 A at cutting plane of 150 m 2. The proposed low-cost and simple fabrication process is applicable for producing MEMS probe beam.
This paper described the development of electrostatically driven peristaltic micropump. The proposed micropump consists of a flexible membrane and a single chamber which electrodes are inserted. The single chamber is divided into smaller cells by the electrodes. The fabricated micropump was operated with four electrodes in the membrane and a various phase sequencing actuation. We studied the changes in the flow rate corresponding to the actuating signal applied to the micropump under the zero hydraulic pressure difference between lnlet port and outlet port. The pump was operated from 60 to 130 V. Whereas the maximum flow rate in basic actuating signal is about 83 1/min at 15 Hz, the maximum flow rate in optimized actuating signal is about 114 l/min at 10 Hz.
We have developed a surface texturing process using a polytetrafluoroethylene coating with a pyramidal structure for obtaining superhydrophobic surfaces. In order to investigate the hydrophobic properties of the surface, we measured the contact angle and roughness values. The calculated roughness factor and root mean square roughness ranged from 2.47 to 2.6 and from 0.25 µm to 0.4 µm, respectively. The contact angle of a water droplet on the surface was greater than 150°; moreover, this angle was maintained for over 7 weeks. This observation implies that extremely low wettability is achievable on superhydrophobic surfaces.
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