Browsing by Author "Hsu, W"

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A low temperature wafer-level hermetic MEMS package using UV curable adhesive
(2004)
Liang, ZH
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Cheng, YT
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Hsu, W
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Lee, YW
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電子工程學系及電子研究所
In order to lower the packaging cost and resolve the process complexity of MEMS fabrications, a new wafer-level post-process hermetic package using UV curable adhesive bonding is introduced for MEMS applications. The UV curable adhesive is cured through UV light exposure without any additional heating, suitable for packaging the devices with temperature sensitive materials or processes. A Pyrex 7740 glass is micromachined and used as a protection cap substrate with microcavities which is spin-coated with the adhesive, aligned, and bonded with a device substrate to form the package after the UV curing. Finally, electrical contact pads expose and die separation are done simultaneously by dicing. Two different monitoring devices, dew point sensor and capacitive accelerometer are built to evaluate the package strength and hermeticity. After dicing operation, no structure damage or stiction phenomenon is found in the packaged capacitive accelerometer. Furthermore, no moisture condensation is observed in the package with 190mum bonding width after 150 minutes boil water immersion. The acceleration test results indicate the package can survive more than 3 weeks at 25degreesC, 100% R.H. (Relative Humidity) working environment.
An electro-thermally driven microactuator with two dimensional motion
(2002-03-01)
Wu, CT
;
Hsu, W
;
機械工程學系
;
Department of Mechanical Engineering
In previous literatures, most of the microactuators were designed to deflect in one dimension only. Here, an electro-thermally driven microactuator with out-of-plane and in-plane two dimensional motion is designed, fabricated and tested. This microactuator comprised of a series of bimorph beams, a moving plate, a lateral driven unit, and contact pads. The out-of-plane motion is produced due to the bimorph effect and residual stress between the layers of Au and polysilicon when they are heated. The in-plane motion is obtained by heating the lateral driven unit which consists of two adjacent beams with different cross sections but the same length, then the asymmetrical thermal expansions in two adjacent beams lead to lateral deflection. The microactuator proposed here is fabricated by surface micromaching technique. A twostep releasing method is used here to free the microactuator successfully. The testing results show that the lateral driven unit can produce 10 mum lateral displacements at input voltages of 5 V, and bimorph structures at the same voltage can produce about 12 mum downward displacement. It is also found that this two dimensional motion can be controlled almost independently.
Characterization of embedded root method in UV-LIGA process
(2003)
Ho, CH
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Hsu, W
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機械工程學系
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Department of Mechanical Engineering
SU-8 photoresist has been popularly used as a mold for electroplating and facilitated low-cost MEMS production in many previous researches. However, the reachable thickness of electroplated structures standing on the substrate were limited to 50 mum below due to the internal stress and deformation of the SU-8 resist in final stripping process. In order to fabricate thicker structures, an embedded root method has been proposed to consolidate the adhesion of the metal structures to the substrate during the SU-8 removal process. In this paper, detailed investigation on this method is conducted to characterize the relationship among the root depth, the line-width and the allowable thickness of the electroplated structures. Some test patterns with embedded roots are designed and tested to generalize the possible extent of various structural scales associated with different niches in depth, which are completely defined through SiO2 masking and KOH etching processes., Based on establishment of the relationship between the root depth and the geometric sizes, a 3-D integrated coil with 200 mum in thickness, 80 mum in width and 4 mum in root depth is successfully released by the SU-8 mold with 400 mum in height, which can not be achieved by the standard SU-8 molding process. The UV-LIGA process presented herein may be applied to the fabrication of other microstructures and microactuators.
Design and fabrication of a three-dimensional long-stretch micro drive by electroplating
(2003)
Wu, CT
;
Tai, WC
;
Hsu, CP
;
Hsu, W
;
機械工程學系
Although lots of works have been devoted to develop the microactuators or microstructures, few researches have been done on three-dimensional microactuators. Here the feasibility investigation on a three-dimensional electrothermally driven long-stretch micro drive (LSMD) is proposed by integrating the LSMD and mechanical hinge mechanism. The LSMD (about 2000 mum x 500 mum) consists of two cascaded compliant structures in parallel. Each cascaded structure is formed by connecting several basic actuation units in series. The mechanical hinge is used to allow the LSMD to be lifted as a three-dimensional structure. One of the important issues in fabricating the three-dimensional microactuator is the conducting circuit to actuate the microactuator. Here the Ni electroplating process is used to fabricate the mechanical hinge structure and the LSMD, then the mechanical hinge itself can act as the conductive circuit easily. From the LSMD simulation results, several design parameters are found to have significant influence on the output displacements. Larger out-stretching displacements are feasible by proper choice of design parameters. Preliminary fabrication results of nickel-made LSMD exhibit output displacement of 190 mum at input voltage of 3 volts. Fabrication results of nickel-made three-dimensional LSMD are also presented.
Experimental study of a variable pressure damper on an automotive valve train
(1998-06-01)
Liou, JJ
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Huang, G
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Hsu, W
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機械工程學系
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Department of Mechanical Engineering
A variable pressure damper (VPD) is proposed here to adjusted the friction force on the valve spring to investigate the relation between the friction force and the valve train. Valve bounce, component separation, spring vibration are observed in the testing. The VPD is shown to have significant improvement in reducing valve bouncing distance and surge vibration under 2985 rpm. Also, experimental results indicate that the component separation becomes more imminent at high speeds with larger damping forces. Here, in certain speed range, a proper frictional force provided by VPD is shown to be able to eliminate bouncing completely without causing component separation.
Fiber-lens-based module for optical recording applications
(2003-07-01)
Tien, CH
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Chou, HL
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Chiu, Y
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Hsu, W
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Milster, TD
An optical fiber-lens-type pickup with numerical aperture (NA) congruent to 0.27 was demonstrated for thermal recording of continuous 1.6-mum-wide lines on MO disks with 50% throughput efficiency. Moreover, a Si-micromachined near-field module integrated with a fiber lens, solid immersion lens (SIL), and submicron aperture was fabricated to improve the mechanical fragility and increase the NA of the optical-fiber-based pickup. The preliminary configuration design and measurement suggest the feasibility of the module as a submicron heat source for high-density optical data storage.
General equations of a helical spring with a cup damper and static verification
(1997-06-01)
Wu, MH
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Ho, JY
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Hsu, W
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機械工程學系
;
Department of Mechanical Engineering
In this study, we derive the general equations of motion for the helical spring with a cup damper by considering the damper's dilation and varying pitch angle of the helical spring. These dynamic equations are simplified to correlate with previous models. The static force-displacement relation is also derived. The extra stiffness due to the damper's dilation considered in the force-displacement relation is the first such modeling in this area. In addition, a method is presented to predict the compressing spring's coil close length and is then verified by experimental data. Moreover, the simulation results of the static force-displacement relation are found to correspond to the experimental data. The maximum error is around 0.6 percent.
General equations of a helical spring with a cup damper and static verification
(1997-06-01)
Wu, MH
;
Ho, JY
;
Hsu, W
;
交大名義發表
;
機械工程學系
In this study, we derive the general equations of motion for the helical spring with a cup damper by considering the damper's dilation and varying pitch angle of the helical spring. These dynamic equations are simplified to correlate with previous models. The static force-displacement relation is also derived. The extra stiffness due to the damper's dilation considered in the force-displacement relation is the first such modeling in this area. In addition, a method is presented to predict the compressing spring's coil close length and is then verified by experimental data. Moreover, the simulation results of the static force-displacement relation are found to correspond to the experimental data. The maximum error is around 0.6 percent.
Integrated near-field optical head for hybrid recording
(2003)
Chiu, Y
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Wu, M
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Shieh, HPD
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Sun, YT
;
Chou, HL
As the recording density of longitudinal magnetic storage increases at a 100% annual growth rate, it will soon approach the superparamagnetic limit where the thermal energy at room temperature starts to induce thermal instability to the grains in the small recorded marks. Thermal magnetic recording schemes, such as those used in magneto-optical recording, help alleviate the problems with the superparamagnetic limit. Recently, a hybrid recording system was proposed where data were recorded thermal magnetically on a magneto-optical disk and read back with a GMR head. In this paper, we propose an integrated planar head that combines an optical fiber lens, a solid immersion lens, a sub wavelength aperture, a micro coil, an air bearing surface, and a GMR head for such a hybrid recording system. Preliminary fabrication and calculation are discussed.
Investigation of torsion springs by considering the friction and the end effect
(1999-12-01)
Wu, MH
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Hsu, W
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機械工程學系
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Department of Mechanical Engineering
In this study, the nonlinearity in moment and angular displacement of torsion springs is studied analytically and experimentally. It is shown that the inclined angles at both ends have direct effects on the nonlinearity of a constant-pitch torsion spring. Also, an algorithm for determining the friction between the spring coils in close-wound torsion springs is proposed. From the comparison to experimental data, it is found that the spring rates are different at forward and backward strokes. The dynamic equations for the close-wound torsion spring is also derived by considering the friction between the spring coils, and two different natural frequencies are found in simulation.
Method on surface roughness modification to alleviate stiction of microstructures
(2003-07-01)
Lee, CC
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Hsu, W
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機械工程學系
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Department of Mechanical Engineering
Modification on surface roughness has been shown to effectively alleviate both release and in-use stiction in the previous literature. However, the modified materials in the previously reported methods were limited to polysilicon or single crystalline silicon with special properties. Here, the proposed modification method not only can apply to silicon without extra property requirements, but also has the potential to modify other materials, such as oxide, nitride, and some metals. The process here combines spin-on photoresist and reactive ion etching. The proposed low temperature process is simple. and no extra mask is needed. Consequently, there is more flexibility to add the roughness modification to the original fabrication process of microdevices. In this study, polysilicon and silicon nitride are demonstrated as the modified materials. Antistiction effects are characterized by calibrating the water contact angles on the modified surfaces and the detachment lengths of released cantilevers. The experimental results show that the detachment length is almost two times longer than the cantilevers without modified substrates, where the interfacial surface energy between solids is reduced about 15 times. (C) 2003 American Vacuum Society.
Modelling of a planar derailleur system on bicycles with experimental verification
(2002)
Lee, B
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Hsu, W
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機械工程學系
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Department of Mechanical Engineering
The major function of the derailleur system is to provide different speed ratios on a multi-speed bicycle. In this study, a mathematical model for the planar derailleur is developed. The planar positions of the guide pulley and the tension pulley at different speed ratios are determined by using geometrical and static analysis. The tension force on the chain in static state is also obtained from the mathematical model. The simulated results are compared to the experimental data at various speed ratios. The maximum error in chain length is about 2.25% between current model and calibrated data. It is found that the effective chain length is the key factor that affects the simulation results. The influence of two torsion spring to the derailleur system is also discussed in this paper. It is found that the value of the tension force is controlled by the spring constants, and two torsion spring's constant ratio affects the positions of the guide pulley and tension pulley directly.
Optimization of an electro-thermally and laterally driven microactuator
(2003-05-01)
Lee, CC
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Hsu, W
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機械工程學系
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Department of Mechanical Engineering
In previous research about thermally and laterally driven microactuators, Guckel et al. proposed a microactuator based on the variable cross sections but the same length of two adjacent beams. Pan and Hsu presented another type of microactuator based on different lengths but the same cross sections of two adjacent beams. Here, a microactuator that combines the traits of those two designs is proposed, optimized, and fabricated. Finite element analysis is performed to obtain the optimal dimensions of the structures when the maximum lateral displacement is achieved. When the air gap is 2 mum, the optimal performance of current design is similar to Guckel's design with optimal dimensions, but it has 65% larger displacement than Pan and Hsu's design at optimal dimensions. For the case of the large air gap beneath the structure (300 mum), the microactuator of current design has more than 25% tip displacement improvement compared to Guckel's or Pan and Hsu's designs. It is also found that the proposed structure is less sensitive to the beam length variations around optimal point no matter in small or large air gap case. Experimental results also verify that the dimension of the air gap affects the thermal boundary condition, so does the performance and optimal architecture of the microactuators.
Performance improvement of an electrothermal microactuator fabricated using Ni-diamond nanocomposite
(2006-02-01)
Tsai, LN
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Shen, GR
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Cheng, YT
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Hsu, W
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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
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Shen, GR
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Cheng, YT
;
Hsu, W
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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.
Revenue management for air cargo space with supply uncertainty
(2005)
Huang, K
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Hsu, W
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運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
This study is aiming to apply the revenue management (RM) concept, a common practice in air passenger operation, to the control of air cargo space. The RM problem of air cargo differs from that of the air passenger in a lot of aspects. The most important one is the uncertainty of air cargo space supply. Meanwhile, the problem of denied boarding caused by supply uncertainty must be dealt with carefully. A single-leg air cargo RM problem is tackled by a dynamic programming (DP) model to derive the optimal control policy and the expected revenue. Numerical experiments based on the actual operational data of a Taiwanese international airline are performed to verify the model. The result shows, to raise revenue by RM, it is critical for the airlines to accurately forecast and control the cargo space supply of a flight.
Sidewall roughness control in advanced silicon etch process
(2003-12-01)
Liu, HC
;
Lin, YH
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Hsu, W
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機械工程學系
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Department of Mechanical Engineering
In ICP-RIE process, there have been many investigations on etching rate. However, only few published reports mentioned the sidewall roughness, which is a critical issue for optical devices. Here, experimental investigations about fabrication parameters in the STS advanced silicon etch (ASE) process for sidewall roughness are performed. In our experiments, several parameters in the ASE process like over time, ramping time, Ar flow rate, platen power, and etching cycle time have been systematically studied. It is found that sidewall mean roughness can be down to 9.11 nm at etching rate of 2.5 mum/min. Comparing with other published works at similar sidewall roughness (around 10 nm), our experimental data have the highest silicon etching rate. For the same STS ICP-RIE systems, our data have smallest sidewall roughness, comparing to previous data published in the litherature.
Tdesign and fabrication of a three-dimensional long-stretch micro drive by electroplating
(2004)
Tai, WC
;
Wu, CT
;
Hsu, CP
;
Hsu, W
;
機械工程學系
Here a three-dimensional micoractuator is proposed by integrating an electro-thermal long stretch micro drive (LSMD) and mechanical hinge mechanism. The mechanical hinge is used to allow the LSMD to be lifted. One of the important issues in fabricating the lifted microactuator is the conducting circuit to actuate the microactuator. Here the electroplating process is used to fabricate the mechanical hinge structure and the LSMD, and then the mechanical hinge itself can act as the conductive circuit easily. The fabrication and testing result show that the three-dimensional LSMD of 2000 mum wide and 500 mum high can stand vertically with output displacement up to 56 mum at input voltage of 2 volts. However, it is found that the output displacement of three-dimensional LSMD is smaller than planar LSMD with substrate beneath due to the lacking of heat conduction at the same input voltage.