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This paper reports fabrication of AuCu alloy microcantilevers by alloy electroplating with a non-cyanide electrolyte and evaluation of the Young's modulus by a resonance frequency method. Length of the microcantilever is ranged from 50 ~ 1000 μm, and the width is from 10 ~ 20 μm. Effects of the applied current density (CD) on the composition, morphology, Vickers hardness, and Young's modulus of the AuCu alloy microcantilever are studied. The copper content increases from 0.8 ~ 10.1 wt% when the CD increased from 0.01 ~0.6 A dm-2. The alloy electroplated at 0.6 A dm-2 shows the highest Vickers hardness at 379 HV. Young's moduli of the AuCu alloy microcantilevers are varied in a range from 70.4 ± 4.2 ~ 80.0 ± 1.9 GPa when the copper content varied from 1.38 ~ 4.03 wt%. [ABSTRACT FROM AUTHOR]

Influences of pulse plating parameters on chemical composition, grain size, morphology and mechanical property of Au-Cu alloy films electrodeposited with an Au-rich sulfite-based electrolyte were investigated. A wide range of Cu concentration (wCu) varied from 3.5 to 26.7 wt% was attained in the Au-Cu films. The galvanic displacement reaction occurred during the off-time period showed great influences on the composition and the grain size. Meanwhile, surface morphology of the Au-Cu films was interrelated with the alloy composition. An increase in the pulsed current density lead to roughening of the surface, and smoothening of the surface was achieved by promoting the displacement reaction. Micro-mechanical properties of the Au-Cu films were evaluated by micro-compression tests for applications as movable micro-components in electronic devices. A pronounced high yield strength at 1.38 GPa was achieved in the Au-Cu film with the smallest grain size at ca. 4.40 nm and the wCu at ca. 15 wt%, which is suggested to be a result of synergetic effects of grain boundary strengthening and solid solution strengthening mechanisms. [ABSTRACT FROM AUTHOR]

This study demonstrated a promising method to integrate flexible silk textiles and conductive Ni-P metal coatings for the increasing interest in wearable devices. Electroless plating with supercritical carbon dioxide (sc-CO2) was utilized to combine the two distinct materials together conformally. Ni-P was chosen for its electrical conductivity and high corrosion resistance while silk was chosen as the substrate for its flexibility. Sc-CO2 was used as a promoter in the catalyzation to enhance the compatibility between the Ni-P with the silk. This technique allows simplification of the electroless plating by excluding the pretreatments while the substrate remains undamaged after the catalyzation step. In addition, the sc-CO2 leads to an environmental friendly process by cutting down the usage of corrosive chemicals in the catalyzation step. This study therefore demonstrates a series of palladium (II) acetylacetonate catalyzation followed by Ni-P deposition on the silk. The lowest electrical resistance at 1.02 Ω was achieved at 4 min of the Ni-P plating time. Corrosion resistance of the Ni-P/silk in a solution simulating the human sweat was evaluated. Reliability of the Ni-P/silk composite material was revealed by comparing the electrical resistances and corrosion resistances before and after an adhesive test. [ABSTRACT FROM AUTHOR]

Au-Cu alloy electroplating is a promising method for fabrication of micro-components used in MEMS devices. Micro-mechanical properties of Au-Cu alloy films fabricated by galvanostatic electroplating are reported in this study. Influences of the current density on surface morphology, crystalline structure, Cu content, and micro-mechanical properties were investigated. An optimum current density at 6 mA/cm#178; was attained for the effects of surface smoothening and grain refinement as the current density was applied in the range of 2-9 mA/cm#178;. Micro-pillars having dimensions of 10 x 10 x 20 µm³ were fabricated from the electroplated Au-Cu alloy films by focus ion beam and used in the uniaxial micro-compression tests. The highest yield stress of 1.15 GPa was achieved from the film electroplated at 6 mA/cm², which the grain size was about 5.3 nm with Cu content of 12.3 wt%. The high yield stress was a synergistic effect of the grain boundary strengthening mechanism with the solid solution strengthening mechanism. [ABSTRACT FROM AUTHOR]

Dense CO2 was applied in electrodeposition of Co films to examine its effects on the morphology, crystal structure, average grain size, and surface roughness. The dense CO2 is referring to CO2 in liquid state (15 MPa and 25°C), subcritical state (15 MPa and 30°C), and supercritical state (15 MPa and 40°C) here. The electrodeposition with dense CO2 was conducted in a high-pressure cell, and the electrolyte was a mixture composed of 20 vol.% of the dense CO2and 80 vol.% of the Co electrolyte. Influences of the temperature and applied current density were also studied. The dense CO2, especially supercritical CO2, was found to be effective in eliminating defects formed in the Co films. Morphology of the Co films changed from ridge-like to hemi-spherical-like and particle-like structures with a decrease in the temperature and an increase in the applied current density. The average grain size was found to decrease with an increase in the current density. The Co films electrodeposited at atmospheric pressure were mainly composed of h.c.p. phase and the crystal structure changed to f.c.c.-rich phase when the dense CO2 was used. [ABSTRACT FROM AUTHOR]

In this paper, a miniaturized concentrator photovoltaic (CPV) system is experimentally demonstrated based on a hot embossing silicone lens array with a size of 2 cm × 2 cm. Owing to the small size of the lens array, the total track of the CPV system can be as small as 4 cm. Consequently, the weight of the CPV system can be much lower than conventional bulky CPV system. For harvesting the diffuse solar radiation, perovskite solar cells are mounted adjacent to a multi-junction solar cell. Theoretically, the short-circuit current of the CPV system can be enhanced from 48.1 to 85.5 mA for γ = 0.7. The enhancement can be much higher for off-normal incident light. This kind of hybrid CPV system will be useful for cloudy weather and also useful for compensating the loss caused by the miss-alignment of the tracking module. [ABSTRACT FROM AUTHOR]