Browsing by Author "Tsai, LN"

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Nanocomposite effects on the coefficient of thermal expansion modification for high performance electro-thermal microactuator
(2005)
Tsai, LN
;
Cheng, YT
;
Hsu, WS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We employ a low-temperature stress-free electroplated nickel (EL) process with the addition of uniformly dispersed nanoparticles of diamond (< 500 nm) or SiO2 (< 80 nm) to investigate "nanocomposite effects" for the first time on the modification of the thermal expansion coefficient (CTE) and other mechanical properties of nickel and its correlation to power and reliability improvement of electro-thermal microactuators. Experimental results show that these material parameters can be either enhanced or deteriorated via the incorporation of different kind of nanopowders. Although the mechanical strength enhancement can be attributed to the intrinsic characteristics of the nanoparticle based on the rule of mixture, the discrepancy of CTE modification can only be explained with distinct composite microstructures which result in the performance improvement of the electro-thermal microactuator. This work has led to a possible research direction in the development of MEMS using the nanocomposites.
Ni-carbon nanotubes nanocomposite for robust microelectromechanical systems fabrication
(2006-01-01)
Tsai, LN
;
Cheng, YT
;
Hsu, WS
;
Fang, WL
;
電子工程學系及電子研究所
This article presents a novel fabrication process to enhance the operational performance and reliability of electrothermal microactuators. Carbon nanotubes (CNTs) (outer diameter: 10-20 nm, innerdiameter: 5-10 nm, length: 0.5-200 mu m) are incorporated in an electrolytic nickel deposition process in which a well-dispersed Ni-CNTs colloidal solution is made by a special acid oxidative method to synthesis a Ni-CNTs nanocomposite for device fabrication. Measurement results show that the microactuator plated with CNTs (0.028 g/L) needs the power requirement less 95% than the pure nickel device at the same output displacement of 3 mu m. The performance improvement of the electrothermal microactuator made of the nanocomposite, including device strength and power efficiency, has shown to be similar to the Ni-diamond composites (L. N. Tsai, G. R. Shen, Y. T. Cheng, and W. S. Hsu, The 54th Electronic Components and Technology Conference, June 2004, pp. 472-476)). In addition, the E/p ratio of the Ni-CNTs composite can be enhanced to 1.47 times higher than that of pure nickel, which is a fascinating result for resonant device fabrication. (c) 2006 American Vacuum Society.
Ni-P-CNTs nanocomposite film for MEMS applications
(2004)
Shen, GR
;
Tsai, LN
;
Chao, TY
;
Cheng, YT
;
Lin, TK
A Ni-P-CNTs (electroless phosphorus nickel-carbon nanotubes) nanocomposite film synthesis and related processes for MEMS device fabrication have been successfully developed and presented in this paper. With a special acid oxidative method, a well-dispersed nickel-CNTs colloidal solution has been produced without any aggregation, very suitable for microstructure fabrication. The nano-indentation measurement indicates that the Young's modulus and hardness of the Ni-P-CNTs nanocomposite film plated in the bath with 0.028g/L CNTs can greatly increase up to 666Pa and 29GPa, respectively, which is four times larger than that of pure nickel: The performance improvement of the electro-thermal microactuator made of the nanocomposite, including device strength and power efficient, have been proved similar to the Ni-diamond composites [1]. With the same power input, the device can provide 4 times elongation longer than that made of pure nickel. The mechanical strength of the actuator can also be enhanced to sustain the input power with two times larger than the pure one.
Performance improvement of an electrothermal microactuator fabricated using Ni-diamond nanocomposite
(2006-02-01)
Tsai, LN
;
Shen, GR
;
Cheng, YT
;
Hsu, W
;
電子工程學系及電子研究所
In this paper, a low-temperature stress-free electrolytic nickel (EL) deposition process with added dispersed diamond nanoparticles (diameter < 0.5 mu m) is developed to synthesize Ni-diamond nanocomposite for fabricating electrothermal microactuators. Device characterization reveals dramatic performance improvements in the electrothermal microactuator that is made of the nanocomposite, including a reduction in the input power requirement and enhanced operation reliability. In comparison with the microactuator made of pure nickel, the nanocomposite one can save about 73% the power for a 3 mu m output displacement and have a longer reversible displacement range, which is prolonged from 1.8 mu m to more than 3 mu m. Furthermore, the nanocomposite device exhibits no performance degradation after more than 100 testing cycles in the reversible regime. The enhancements increase with the incorporation of the nanodiamond in a nickel matrix, so the Ni-diamond nanocomposite has potential for application in MEMS fabrication.
Power and reliability improvement of an electro-thermal microactuator using Ni-diamond nanocomposite
(2004)
Tsai, LN
;
Shen, GR
;
Cheng, YT
;
Hsu, W
;
電子工程學系及電子研究所
Here a low-temperature stress-free electrolytic nickel (EL) deposition process with the addition of uniformly dispersed diamond nanoparticles (diameter < 0.5 mum) is propose to fabricate cantilevers and electro-thermal microactuators to demonstrate the improvement of the device on reducing input power requirement and enhancing operation reliability. The fabrication results show that the nanodiamond particles are successfully dispersed in the electroplating nickel layers. By calibrating the resonant frequencies of nickel cantilevers with different concentrations of diamond nanoparticles, the E/pratio of cantilevers can be enhanced 7.1 times with diamond nanoparticles of 2 g/l in the proposed electrolytic nickel (EL) deposition process. From displacement tests, the electro-thermal microactuator with nanodiamond particles of 2 g/l reduces 73% power requirement of pure nickel device needed at the same output displacement of 3 mum. Also, the reversible displacement range is found to be expanded from 1.8 mum to 3 mum by adding nanodiamond particles of 2 g/l in the nickel electro-thermal microactuators.
Synthesis and characterization of Ni-P-CNT's nanocomposite film for MEMS applications
(2005-09-01)
Shen, GR
;
Cheng, YT
;
Tsai, LN
;
機械工程學系
;
電子工程學系及電子研究所
An electroless phosphorus nickel-carbon nanotube's (Ni-P-CNT) nanocomposite film synthesis and related process for microelectromechanical systems device fabrication have been successfully developed and presented in this paper. With a special acid oxidative method, a well-dispersed nickel-CNT's colloidal solution has been produced without any aggregation, which is very suitable for microstructure fabrication. The nanoindentation measurement indicates that the Young's modulus and hardness of the Ni-P-CNT's nanocomposite film plated in the bath with 0.028-g/L CNTs can greatly increase up to 665.9 and 28.9 GPa, respectively, which are approximately four times larger than that of pure nickel. Moreover, the content of CNTs in the Ni-P-CNT's films is measured by an elemental analyzer. Via the electrical resistivity measurement using a four-point probe, it is found that the electrical property of the nanocomposite film can be well characterized using a Maxwell-Wagner model for a two-phase mixture. The performance improvements of the electrothermal microactuator made of the nanocomposite, including device strength and power efficiency, have been proven similar to the actuator made of the Ni-diamond composites by electrolytic plating by Tsai et al, but with more efficiency and higher strength than the Ni-diamond device does.