Eight adducts of Rh2(O2CCH3)4 with axial pyridine derivatives that contain hydrogen-bonding amino and/or steric methyl substituents in the 2- and 6-positions have been prepared and examined by electronic absorption and 1H NMR spectroscopy in solution and by elemental, IR, thermogravimetric, and X-ray diffraction analyses in the solid state. The results indicated that strong hydrogen bonding interactions between Rh2(O2CCH3)4 and axially coordinated pyridine derivatives with a 2- or 6-amino group occur in both solution and the solid state and contribute to the higher thermal stability of the molecular assembly of dirhodium complexes. It was demonstrated that such a combination of coordinate and hydrogen bonds is useful as a building tool in designing and constructing new organic-inorganic hybridized compounds and supramolecular architectures.
Low-temperature microjoining, such as wire (or ribbon) bonding, tape automated bonding (TAB), and flip chip bonding (FCB), is necessary for electronics packaging. Each type of microjoining takes on various aspects but has common bonding mechanisms regarding friction slip, plastic deformation, and friction heating. In the present paper, solid-state microjoining mechanisms in Au wire (ball) bonding, FCB, Al wire bonding (WB), and Al ribbon bonding are discussed to systematically understand the common bonding mechanisms. Ultrasonic vibration enhances friction slip and plastic deformation, making it possible to rapidly obtain dry interconnects. Metallic adhesion at the central area of the bonding interface is mainly produced by the friction slip. On the other hand, the folding of the lateral side surfaces of the Au bump, Au ball, and Al wire is very important for increasing the bonded area. The central and peripheral adhesions are achieved by a slip-and-fold mechanism. The solid-state microjoining mechanisms of WB and FCB are discussed based on experimental results.
This paper reports the results of the miniaturization design of a permanent-magnet synchronous motor, for which an optimal design technique based on thermomagnetic field coupling analysis is used. We derived the optimal solutions for various motor flatness ratios and determined the relationship between the motor size and the flatness ratio. For motors with different flatness ratios, we calculated the speed-torque characteristics by considering the voltage, temperature rise, and demagnetization limits and compared them. Moreover, we manufactured and tested the smallest designed motor. The measured temperature rises demonstrated the high accuracy of the proposed miniaturization design.
The deformation behavior of thick Al wires and the expansion behavior of the bond area during ultrasonic wedge bonding to AlSi, Si and SiO 2 substrates were measured simultaneously in detail with a high-speed measuring system. The deformation of the wire by the application of the bonding force is completed immediately. The deformation restarts by the application of the ultrasonic vibration. The deformation induced by applying the bonding force consists of only elastic component, whereas that by ultrasonic vibration consists of only plastic component. The Al wire is not work-hardened by the plastic deformation during application of ultrasonic vibration. The adhered area expands to the direction perpendicular to the ultrasonic vibration. The evolution of the wire deformation behavior and the expansion of the adhered area show an intimate correlation with each other.
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