shyh-biau jiang - Academia.edu (original) (raw)
Papers by shyh-biau jiang
IEEE Sensors Journal, May 1, 2023
IEEE Access, 2023
In this paper, an innovative control method, namely angle-current dual-loop feedback control, is ... more In this paper, an innovative control method, namely angle-current dual-loop feedback control, is proposed for use with microstepping motors. This method involves adjusting the stator excitation angle and current simultaneously on the basis of the feedback angle of the sensor on the microstepping motor. The proposed method is expected to enhance the positioning accuracy and energy efficiency of stepping motors. The proposed method was tested by implementing it in a microstepping motor control system, which included a core microcontroller unit circuit, dual-H-bridge pulse width modulation drive circuit, current sensing circuit, and angle sensing encoder readback circuit. An algorithm based on the proposed method was developed, and data sampling, storage, and return communication functions, which are convenient for experimental verification, were included in this algorithm. To verify that the proposed method is superior to traditional open-loop control and excitation angle feedback control, a testing platform was used to measure the differences in positioning accuracy and drive power under the three control methods and biased torsion loads. The results indicate that compared with the other two control methods, the proposed control method improves the positioning accuracy and reduces the power consumption of a stepping motor. INDEX TERMS Angle control, current control, dual loop, positioning accuracy, power efficiency, stepping motor.
IEEE Transactions on Instrumentation and Measurement, Mar 1, 2011
This paper proposes an innovative ultrasonic time of flight (TOF) measurement method with narrow-... more This paper proposes an innovative ultrasonic time of flight (TOF) measurement method with narrow-band transducers. By introducing the received ultrasonic wave peak time sequences (PTSs) of two slightly different frequencies, the relative TOF can be accurately identified with a much better resolution than a wave period. The new PTS TOF measurement is achieved in two steps. First, a PTS is built for receiving the ultrasound signal of each frequency according to the arrival time of the wave peaks by calculating the mean value of the adjacent crossover time. Second, the arrival time of the wave front is rebuilt by estimating the common initiation time of the PTSs for the received waves of slightly different frequencies. A mathematical model is derived to describe the signal reception, from which the TOF estimation algorithm was derived. A simulation model describing the characteristics of the ultrasonic transducer and the ultrasonic wave propagation physics was developed to verify the feasibility of the new algorithm. Finally, an experimental system for measuring the relative TOF over the known distance of 550-1450 mm was implemented to confirm feasibility and to demonstrate that a subwavelength resolution of 0.015 times of the wavelength was indeed achievable in measuring distances over meters. Index Terms-Distance measurement, peak time sequence (PTS), time of flight (TOF), ultrasonic wave, ultrasound.
IEEE Transactions on Signal Processing, 1995
An unwindowed (or covariance) multichannel lattice filter for recursive least-squares estimation ... more An unwindowed (or covariance) multichannel lattice filter for recursive least-squares estimation is derived. The channels are orthogonalized to eliminate the need for matrix inversion. The channel-orthogonalization process leads to forwardpropagating and backward-propagating blocks in both the lattice filter and the model-parameter construction algorithm. These blocks are particularly suitable for array processing, as illustrated by arrays presented in the paper.
[1992] Proceedings of the 31st IEEE Conference on Decision and Control
The mixing of two fluids in a plane shear layer can be affected by time-dependent heating of one ... more The mixing of two fluids in a plane shear layer can be affected by time-dependent heating of one side of the flow partition. The authors describe the development of an adaptive linear-quadratic-Gaussian controller for a functional differential equation whose solutions display some of the characteristics of the motion of the Kelvin-Helmholtz layer separating the two streams. The delay differential equation
A new multichannel lattice filter is used to identify a multichannel ARMA model for a large flexi... more A new multichannel lattice filter is used to identify a multichannel ARMA model for a large flexible truss from experimental data. The numerical results demonstrate the fast convergence of the adaptive lattice filter, and illustrate the importance of using multiple measurement channels simultaneously in identifying flexible structures with repeated or nearly repeated frequencies.
IEEE Access
This work was supported by Roboy Venture Capital Company Ltd., which is a venture capital company... more This work was supported by Roboy Venture Capital Company Ltd., which is a venture capital company in Taiwan, it provides funds to help the researchers to realize the research if the researchers have innovative research ideas. The finance support includes the personnel fees of research, materials of research, and publishing fees of paper.
Living Planet Symposium 2016, Aug 1, 2016
Materials Science Forum, 2006
This article releases the details of the equipment development for the micro-anode guided electro... more This article releases the details of the equipment development for the micro-anode guided electroplating MAGE fabrication. The microstepping architecture, electroplating power source, control system architecture, measurement system, man machine interface and the control prodedure will be described. Metallic columns around 100 micrometers in diameter were fabricated up to 2cm long with this equipment to demonstrate its performance. An innovative intermittent MAGE mode is supported by this equipment so that it can produce micro columns of finer surface morphology and better circumferential uniformity than the conventional continuous electroplating.
This article releases the details of the digital imaging enhancement for the micro-anode guided e... more This article releases the details of the digital imaging enhancement for the micro-anode guided electroplating MAGE fabrication equipment. The control system architecture, the micro stepping architecture, the electroplating power source, the measurement system, the man machine interface, the control procedure and the digital imaging subsystem are described. The profile of the electroplating deposit during the initiation phase as monitored in real-time by the new imaging subsystem could verify the simulation prediction.
Advances in Space Research
Abstract We propose an airglow instrument design that can expand the dynamic range of light inten... more Abstract We propose an airglow instrument design that can expand the dynamic range of light intensity and have the effect of glare protection. This innovative airglow instrument employs the photon count detected by a photomultiplier tube (PMT) as feedback to control the high voltage of the PMT to compensate for any change of light intensity and to maintain the photon count fixed. When the photon count is controlled to remain fixed, the high voltage is inversely proportional to the light intensity so that the light intensity can be estimated from the high voltage. A mathematical model can be surface fitted to the experimental data, and by using this model, the light intensity can be obtained from the photon count and the high voltage. Through the light intensity and the preset photon count, the high voltage for feedforward compensation can be calculated, and then the high voltage adjusted. In this way, the feedforward PMT characteristic compensation control is completed. Additionally, the feedback includes a proportional-integral linear control to eliminate the influence of this model error and to make the measured photon count closer to the preset photon count. We conducted laboratory testing to confirm that the innovative instrument can achieve the design goals. The new instrument expands the linear dynamic range while maintaining high sensitivity.
Energies
To improve the reliability and energy efficiency of battery swapping, we constructed a battery po... more To improve the reliability and energy efficiency of battery swapping, we constructed a battery power network system with active redundancies and with multiple battery management controllers (one in each newly developed smart redundant battery pack). Each pack is getting ready to assume the role of the major to coordinate direct safe mounting of the packs onto the power bus for load sharing or charging without the need for a direct current to direct current converter. This fault-tolerant architecture provides multiple backups in both management control and power supply. To verify this design, the mounting, insertion, and removal of the battery packs were executed during charging and discharging. Battery packs can be swapped on and off safely at any time regardless of their charging states. Battery packs can be direct safe mounted onto the power bus by a threshold algorithm. With each mount on event, the equivalent output energy conversion efficiency ranges from 98.3% to 99.2% through...
Energies
With regard to the best electro-chemical efficiency of an active direct methanol fuel cell (DMFC)... more With regard to the best electro-chemical efficiency of an active direct methanol fuel cell (DMFC), the stacks and their balance of plant (BOP) are complex to build and operate. The yield of making the large-scale stacks is difficult to improve. Therefore, a portable power station made of multiple simpler planar type stack modules with only appropriate semi-active BOPs was developed. A planar stack and its miniature BOP components are integrated into a semi-active DMFC stack module for easy production, assembly, and operation. An improved energy management system is designed to control multiple DMFC stack modules in parallel to enhance its power-generation capacity and stability so that the portability, environmental tolerance, and long-term durability become comparable to that of the active systems. A prototype of the power station was tested for 3600 h in an actual outdoor environment through winter and summer. Its performance and maintenance events are analyzed to validate its sta...
Journal of Geophysical Research: Space Physics, 2014
It has been well known that the ionospheric electron density N e is greater in the summer nightti... more It has been well known that the ionospheric electron density N e is greater in the summer nighttime than daytime around the Weddell Sea region, which is named Weddell Sea Anomaly (WSA). This paper for the first time reports unusual increases (decreases) of the daytime (nighttime) electron temperature T e at about 830 km altitude over the WSA latitudes probed by Tatiana-2 during December 2009 to January 2010. Concurrent measurements at 660-830 km altitude observed by Tatiana-2, Detection of ElectroMagnetic Emissions Transmitted from Earthquake Regions (DEMETER), and Formosa Satellite 3/Constellation Observing System for Meteorology, Ionosphere and Climate (F3/C) reveal the anticorrelation between T e and N e along the WSA latitudes in the daytime and nighttime. Based on F3/C N e along the WSA latitudes observed at various local times, the associated T e values are computed. The Tatiana-2 and DEMETER observations as well as the computed results show that T e yield the maximum values over the WSA region during daytime and over the Indian and Atlantic Ocean area during nighttime. The maxima or minima in F3/C N e and the computed T e reveal eastward phase shifts. In this study, we cross compare N e at 700 km altitude by F3/C, T e at 830 km altitude observed by Tatiana-2, and T e /N e at 660 km altitude probed by DEMETER to find the relationship between the two quantities along the WSA latitudes during the period of
Journal of Micromechanics and Microengineering, 2009
ABSTRACT Localized Ni deposition improved by saccharin sodium (SS) in the intermittent microanode... more ABSTRACT Localized Ni deposition improved by saccharin sodium (SS) in the intermittent microanode guided electroplating (intermittent MAGE) process has been investigated. This effect is more complicated than conventional planar electroplating. If there was an insignificant amount of SS in the bath (i.e. less than 1.0 mM), then the radius of the fabricated nodular columns would range from 37.5 to 42.5 µm cyclically along the axis and the surface would be covered with a homogeneous layer of 3–8 µm Ni particles. In the presence of an optimal amount of SS (i.e. around 1.0–3.0 mM), columns with uniform radius (around 42.5 µm) were fabricated and the surface was covered by a homogeneous layer of fine Ni particles (i.e. diameter 1 µm). With higher SS (4.0–6.0 mM in the bath), columns were constructed with uniform radius but the surface was covered by alternating zones of coarse and fine Ni particles. For SS beyond critical concentrations (8.0 mM at 4.0 V and 10.0 mM at 4.5 and 5.0 V), no microcolumn could be constructed and a universal planar Ni deposition on the substrate was formed instead. SS is an absorbent and it leads to cathodic polarization in the electroplating process. The influence of SS on the asymmetrical electric field distributed in the local area and formed by localized electrochemical deposition (LECD) has been studied by the use of the proposed model in this work and commercial finite element software.
Journal of Micromechanics and Microengineering, 2009
Micrometer Ni–Cu alloy columns have been fabricated by the micro-anode-guided electroplating (MAG... more Micrometer Ni–Cu alloy columns have been fabricated by the micro-anode-guided electroplating (MAGE) process in the citrate bath. The surface morphology and chemical composition of the micro-columns were determined by copper concentration in the bath and by the electrical bias of MAGE. When fabricated in a bath of dilute copper (i.e. 4 mM) at lower voltages (e.g. 3.8 and 4.0 V), the alloy micro-columns revealed uniform diameter and smooth appearance. The alloy composition demonstrated an increase in the wt% ratio of Ni/Cu from 75/25, 80/20, 83/17 to 87/13 with increasing electrical bias from 3.8, 4.0, 4.2 to 4.4 V. However, it decreases from 75/25, 57/43 to 47/53 with increasing copper concentration from 4, 8 to 12 mM in the bath. Citrate plays a role in forming complexes with nickel and copper at similar reduction potentials, thus reducing simultaneously to Ni–Cu alloy. The mechanism for fabricating alloy micro-columns could be delineated on the basis of cathodic polarization of the complexes. A couple of micro-columns were fabricated using MAGE in constructing a pure copper micro-column on the top of a Ni/Cu (at 47/53) alloy micro-column. This micro-thermocouple provides a satisfactory measurement with good sensitivity and precision.
Journal of Micromechanics and Microengineering, 2007
ABSTRACT Micrometer nickel columns were fabricated locally on a copper substrate in a Watts bath ... more ABSTRACT Micrometer nickel columns were fabricated locally on a copper substrate in a Watts bath by microanode guided electroplating which is commonly known as localized electrochemical deposition (LECD). A microanode of platinum (125 µm in diameter) served to move up intermittently, thus guiding the growth of Ni deposit from the substrate. The separation between the microanode and top of the microcolumn was initially set at 10 µm before setting out the electroplating. The electroplating current and local potential near the local region after the LECD were monitored and examined in this work. Surface and transverse morphology of the microcolumns were examined through a scanning electron microscope. LECD performed at biases less than 3.56 ± 0.01 V led to columns with smooth surfaces and circular internal transverse fully compacted, whereas when performed at biases higher than 3.56 ± 0.01 V it led to columns with a rough surface and distorted circular internal transverse with porosity in the center. The higher the bias, the worse the surface smoothness. The less circular the transverse, the less compactness in the transverse center. A compromise between the estimated supplying rate and the consumption rate of the nickel ions in the local region after the LECD is discussed to understand the dependence of the morphologies on the biases.
Journal of Micromechanics and Microengineering, 2008
ABSTRACT The localization of localized electrochemical deposition (LECD) was investigated using t... more ABSTRACT The localization of localized electrochemical deposition (LECD) was investigated using the microanode-guided electroplating (MAGE) technique. Two modes (i.e., one-step and intermittent-step) of the MAGE process were employed to explore the circular area around the bottom of the copper microcolumns deposited on a substrate. The diameter was utilized to estimate the localization occupied by the column instead of using the bottom area. For the hillocks deposited by one-step MAGE, the localization diameter increases with increasing the electric biases between the microanode and the substrate. For the copper microcolumns fabricated by intermittent-step MAGE, the localization diameter increases to a critical magnitude and levels off upon increasing the height of the columns. The critical localization diameter was found to be dependent on the electric biases and the initial gap between the microanode and the top of the microcolumn deposited earlier. The less the electric biases and the initial gap in intermittent MAGE, the smaller the localization diameter of the microcolumn. A model is proposed to illustrate the localization defined by one-step MAGE and the critical localization diameter (Dc) obtained from intermittent-step MAGE. A relationship between the ratio of the conical core strength to the conical periphery strength (i.e., Ecore/Ep) and the electric bias has been established for the critical localization diameter of the microcolumns. The strength ratio can be used as a criterion to predict whether a localization diameter increases or not.
IEEE Sensors Journal, May 1, 2023
IEEE Access, 2023
In this paper, an innovative control method, namely angle-current dual-loop feedback control, is ... more In this paper, an innovative control method, namely angle-current dual-loop feedback control, is proposed for use with microstepping motors. This method involves adjusting the stator excitation angle and current simultaneously on the basis of the feedback angle of the sensor on the microstepping motor. The proposed method is expected to enhance the positioning accuracy and energy efficiency of stepping motors. The proposed method was tested by implementing it in a microstepping motor control system, which included a core microcontroller unit circuit, dual-H-bridge pulse width modulation drive circuit, current sensing circuit, and angle sensing encoder readback circuit. An algorithm based on the proposed method was developed, and data sampling, storage, and return communication functions, which are convenient for experimental verification, were included in this algorithm. To verify that the proposed method is superior to traditional open-loop control and excitation angle feedback control, a testing platform was used to measure the differences in positioning accuracy and drive power under the three control methods and biased torsion loads. The results indicate that compared with the other two control methods, the proposed control method improves the positioning accuracy and reduces the power consumption of a stepping motor. INDEX TERMS Angle control, current control, dual loop, positioning accuracy, power efficiency, stepping motor.
IEEE Transactions on Instrumentation and Measurement, Mar 1, 2011
This paper proposes an innovative ultrasonic time of flight (TOF) measurement method with narrow-... more This paper proposes an innovative ultrasonic time of flight (TOF) measurement method with narrow-band transducers. By introducing the received ultrasonic wave peak time sequences (PTSs) of two slightly different frequencies, the relative TOF can be accurately identified with a much better resolution than a wave period. The new PTS TOF measurement is achieved in two steps. First, a PTS is built for receiving the ultrasound signal of each frequency according to the arrival time of the wave peaks by calculating the mean value of the adjacent crossover time. Second, the arrival time of the wave front is rebuilt by estimating the common initiation time of the PTSs for the received waves of slightly different frequencies. A mathematical model is derived to describe the signal reception, from which the TOF estimation algorithm was derived. A simulation model describing the characteristics of the ultrasonic transducer and the ultrasonic wave propagation physics was developed to verify the feasibility of the new algorithm. Finally, an experimental system for measuring the relative TOF over the known distance of 550-1450 mm was implemented to confirm feasibility and to demonstrate that a subwavelength resolution of 0.015 times of the wavelength was indeed achievable in measuring distances over meters. Index Terms-Distance measurement, peak time sequence (PTS), time of flight (TOF), ultrasonic wave, ultrasound.
IEEE Transactions on Signal Processing, 1995
An unwindowed (or covariance) multichannel lattice filter for recursive least-squares estimation ... more An unwindowed (or covariance) multichannel lattice filter for recursive least-squares estimation is derived. The channels are orthogonalized to eliminate the need for matrix inversion. The channel-orthogonalization process leads to forwardpropagating and backward-propagating blocks in both the lattice filter and the model-parameter construction algorithm. These blocks are particularly suitable for array processing, as illustrated by arrays presented in the paper.
[1992] Proceedings of the 31st IEEE Conference on Decision and Control
The mixing of two fluids in a plane shear layer can be affected by time-dependent heating of one ... more The mixing of two fluids in a plane shear layer can be affected by time-dependent heating of one side of the flow partition. The authors describe the development of an adaptive linear-quadratic-Gaussian controller for a functional differential equation whose solutions display some of the characteristics of the motion of the Kelvin-Helmholtz layer separating the two streams. The delay differential equation
A new multichannel lattice filter is used to identify a multichannel ARMA model for a large flexi... more A new multichannel lattice filter is used to identify a multichannel ARMA model for a large flexible truss from experimental data. The numerical results demonstrate the fast convergence of the adaptive lattice filter, and illustrate the importance of using multiple measurement channels simultaneously in identifying flexible structures with repeated or nearly repeated frequencies.
IEEE Access
This work was supported by Roboy Venture Capital Company Ltd., which is a venture capital company... more This work was supported by Roboy Venture Capital Company Ltd., which is a venture capital company in Taiwan, it provides funds to help the researchers to realize the research if the researchers have innovative research ideas. The finance support includes the personnel fees of research, materials of research, and publishing fees of paper.
Living Planet Symposium 2016, Aug 1, 2016
Materials Science Forum, 2006
This article releases the details of the equipment development for the micro-anode guided electro... more This article releases the details of the equipment development for the micro-anode guided electroplating MAGE fabrication. The microstepping architecture, electroplating power source, control system architecture, measurement system, man machine interface and the control prodedure will be described. Metallic columns around 100 micrometers in diameter were fabricated up to 2cm long with this equipment to demonstrate its performance. An innovative intermittent MAGE mode is supported by this equipment so that it can produce micro columns of finer surface morphology and better circumferential uniformity than the conventional continuous electroplating.
This article releases the details of the digital imaging enhancement for the micro-anode guided e... more This article releases the details of the digital imaging enhancement for the micro-anode guided electroplating MAGE fabrication equipment. The control system architecture, the micro stepping architecture, the electroplating power source, the measurement system, the man machine interface, the control procedure and the digital imaging subsystem are described. The profile of the electroplating deposit during the initiation phase as monitored in real-time by the new imaging subsystem could verify the simulation prediction.
Advances in Space Research
Abstract We propose an airglow instrument design that can expand the dynamic range of light inten... more Abstract We propose an airglow instrument design that can expand the dynamic range of light intensity and have the effect of glare protection. This innovative airglow instrument employs the photon count detected by a photomultiplier tube (PMT) as feedback to control the high voltage of the PMT to compensate for any change of light intensity and to maintain the photon count fixed. When the photon count is controlled to remain fixed, the high voltage is inversely proportional to the light intensity so that the light intensity can be estimated from the high voltage. A mathematical model can be surface fitted to the experimental data, and by using this model, the light intensity can be obtained from the photon count and the high voltage. Through the light intensity and the preset photon count, the high voltage for feedforward compensation can be calculated, and then the high voltage adjusted. In this way, the feedforward PMT characteristic compensation control is completed. Additionally, the feedback includes a proportional-integral linear control to eliminate the influence of this model error and to make the measured photon count closer to the preset photon count. We conducted laboratory testing to confirm that the innovative instrument can achieve the design goals. The new instrument expands the linear dynamic range while maintaining high sensitivity.
Energies
To improve the reliability and energy efficiency of battery swapping, we constructed a battery po... more To improve the reliability and energy efficiency of battery swapping, we constructed a battery power network system with active redundancies and with multiple battery management controllers (one in each newly developed smart redundant battery pack). Each pack is getting ready to assume the role of the major to coordinate direct safe mounting of the packs onto the power bus for load sharing or charging without the need for a direct current to direct current converter. This fault-tolerant architecture provides multiple backups in both management control and power supply. To verify this design, the mounting, insertion, and removal of the battery packs were executed during charging and discharging. Battery packs can be swapped on and off safely at any time regardless of their charging states. Battery packs can be direct safe mounted onto the power bus by a threshold algorithm. With each mount on event, the equivalent output energy conversion efficiency ranges from 98.3% to 99.2% through...
Energies
With regard to the best electro-chemical efficiency of an active direct methanol fuel cell (DMFC)... more With regard to the best electro-chemical efficiency of an active direct methanol fuel cell (DMFC), the stacks and their balance of plant (BOP) are complex to build and operate. The yield of making the large-scale stacks is difficult to improve. Therefore, a portable power station made of multiple simpler planar type stack modules with only appropriate semi-active BOPs was developed. A planar stack and its miniature BOP components are integrated into a semi-active DMFC stack module for easy production, assembly, and operation. An improved energy management system is designed to control multiple DMFC stack modules in parallel to enhance its power-generation capacity and stability so that the portability, environmental tolerance, and long-term durability become comparable to that of the active systems. A prototype of the power station was tested for 3600 h in an actual outdoor environment through winter and summer. Its performance and maintenance events are analyzed to validate its sta...
Journal of Geophysical Research: Space Physics, 2014
It has been well known that the ionospheric electron density N e is greater in the summer nightti... more It has been well known that the ionospheric electron density N e is greater in the summer nighttime than daytime around the Weddell Sea region, which is named Weddell Sea Anomaly (WSA). This paper for the first time reports unusual increases (decreases) of the daytime (nighttime) electron temperature T e at about 830 km altitude over the WSA latitudes probed by Tatiana-2 during December 2009 to January 2010. Concurrent measurements at 660-830 km altitude observed by Tatiana-2, Detection of ElectroMagnetic Emissions Transmitted from Earthquake Regions (DEMETER), and Formosa Satellite 3/Constellation Observing System for Meteorology, Ionosphere and Climate (F3/C) reveal the anticorrelation between T e and N e along the WSA latitudes in the daytime and nighttime. Based on F3/C N e along the WSA latitudes observed at various local times, the associated T e values are computed. The Tatiana-2 and DEMETER observations as well as the computed results show that T e yield the maximum values over the WSA region during daytime and over the Indian and Atlantic Ocean area during nighttime. The maxima or minima in F3/C N e and the computed T e reveal eastward phase shifts. In this study, we cross compare N e at 700 km altitude by F3/C, T e at 830 km altitude observed by Tatiana-2, and T e /N e at 660 km altitude probed by DEMETER to find the relationship between the two quantities along the WSA latitudes during the period of
Journal of Micromechanics and Microengineering, 2009
ABSTRACT Localized Ni deposition improved by saccharin sodium (SS) in the intermittent microanode... more ABSTRACT Localized Ni deposition improved by saccharin sodium (SS) in the intermittent microanode guided electroplating (intermittent MAGE) process has been investigated. This effect is more complicated than conventional planar electroplating. If there was an insignificant amount of SS in the bath (i.e. less than 1.0 mM), then the radius of the fabricated nodular columns would range from 37.5 to 42.5 µm cyclically along the axis and the surface would be covered with a homogeneous layer of 3–8 µm Ni particles. In the presence of an optimal amount of SS (i.e. around 1.0–3.0 mM), columns with uniform radius (around 42.5 µm) were fabricated and the surface was covered by a homogeneous layer of fine Ni particles (i.e. diameter 1 µm). With higher SS (4.0–6.0 mM in the bath), columns were constructed with uniform radius but the surface was covered by alternating zones of coarse and fine Ni particles. For SS beyond critical concentrations (8.0 mM at 4.0 V and 10.0 mM at 4.5 and 5.0 V), no microcolumn could be constructed and a universal planar Ni deposition on the substrate was formed instead. SS is an absorbent and it leads to cathodic polarization in the electroplating process. The influence of SS on the asymmetrical electric field distributed in the local area and formed by localized electrochemical deposition (LECD) has been studied by the use of the proposed model in this work and commercial finite element software.
Journal of Micromechanics and Microengineering, 2009
Micrometer Ni–Cu alloy columns have been fabricated by the micro-anode-guided electroplating (MAG... more Micrometer Ni–Cu alloy columns have been fabricated by the micro-anode-guided electroplating (MAGE) process in the citrate bath. The surface morphology and chemical composition of the micro-columns were determined by copper concentration in the bath and by the electrical bias of MAGE. When fabricated in a bath of dilute copper (i.e. 4 mM) at lower voltages (e.g. 3.8 and 4.0 V), the alloy micro-columns revealed uniform diameter and smooth appearance. The alloy composition demonstrated an increase in the wt% ratio of Ni/Cu from 75/25, 80/20, 83/17 to 87/13 with increasing electrical bias from 3.8, 4.0, 4.2 to 4.4 V. However, it decreases from 75/25, 57/43 to 47/53 with increasing copper concentration from 4, 8 to 12 mM in the bath. Citrate plays a role in forming complexes with nickel and copper at similar reduction potentials, thus reducing simultaneously to Ni–Cu alloy. The mechanism for fabricating alloy micro-columns could be delineated on the basis of cathodic polarization of the complexes. A couple of micro-columns were fabricated using MAGE in constructing a pure copper micro-column on the top of a Ni/Cu (at 47/53) alloy micro-column. This micro-thermocouple provides a satisfactory measurement with good sensitivity and precision.
Journal of Micromechanics and Microengineering, 2007
ABSTRACT Micrometer nickel columns were fabricated locally on a copper substrate in a Watts bath ... more ABSTRACT Micrometer nickel columns were fabricated locally on a copper substrate in a Watts bath by microanode guided electroplating which is commonly known as localized electrochemical deposition (LECD). A microanode of platinum (125 µm in diameter) served to move up intermittently, thus guiding the growth of Ni deposit from the substrate. The separation between the microanode and top of the microcolumn was initially set at 10 µm before setting out the electroplating. The electroplating current and local potential near the local region after the LECD were monitored and examined in this work. Surface and transverse morphology of the microcolumns were examined through a scanning electron microscope. LECD performed at biases less than 3.56 ± 0.01 V led to columns with smooth surfaces and circular internal transverse fully compacted, whereas when performed at biases higher than 3.56 ± 0.01 V it led to columns with a rough surface and distorted circular internal transverse with porosity in the center. The higher the bias, the worse the surface smoothness. The less circular the transverse, the less compactness in the transverse center. A compromise between the estimated supplying rate and the consumption rate of the nickel ions in the local region after the LECD is discussed to understand the dependence of the morphologies on the biases.
Journal of Micromechanics and Microengineering, 2008
ABSTRACT The localization of localized electrochemical deposition (LECD) was investigated using t... more ABSTRACT The localization of localized electrochemical deposition (LECD) was investigated using the microanode-guided electroplating (MAGE) technique. Two modes (i.e., one-step and intermittent-step) of the MAGE process were employed to explore the circular area around the bottom of the copper microcolumns deposited on a substrate. The diameter was utilized to estimate the localization occupied by the column instead of using the bottom area. For the hillocks deposited by one-step MAGE, the localization diameter increases with increasing the electric biases between the microanode and the substrate. For the copper microcolumns fabricated by intermittent-step MAGE, the localization diameter increases to a critical magnitude and levels off upon increasing the height of the columns. The critical localization diameter was found to be dependent on the electric biases and the initial gap between the microanode and the top of the microcolumn deposited earlier. The less the electric biases and the initial gap in intermittent MAGE, the smaller the localization diameter of the microcolumn. A model is proposed to illustrate the localization defined by one-step MAGE and the critical localization diameter (Dc) obtained from intermittent-step MAGE. A relationship between the ratio of the conical core strength to the conical periphery strength (i.e., Ecore/Ep) and the electric bias has been established for the critical localization diameter of the microcolumns. The strength ratio can be used as a criterion to predict whether a localization diameter increases or not.