Copper metal is widely electroplated for microelectronic interconnections such as redistribution layers(RDL),pillar bumps,through silicon vias,etc.With advances of multilayered RDL,via-on-via structures have been deve...Copper metal is widely electroplated for microelectronic interconnections such as redistribution layers(RDL),pillar bumps,through silicon vias,etc.With advances of multilayered RDL,via-on-via structures have been developed for ultrahigh-density any-layer interconnection,which expects superconformal filling of interlayer low aspect-ratio vias jointly with coplanar lines and pads.However,it poses a great challenge to electrodeposition,because current via fill mechanisms are stemming from middle to high aspect-ratio(>0.8)vias and lacking applicability in low aspect-ratio(<0.3)RDL-vias,where via geometry related electric-flow fields coupling must be reconsidered.In the present work,a four-additive strategy has been developed for RDL-vias fill and thoroughly investigated from additive electrochemistry,in situ Raman spectroelectrochemistry,and quantum chemistry perspectives.A novel adsorbate configuration controlled(ACC)electrodeposition mechanism is established that at weak-convection bilateral edges and lower corners,the adsorbate displays a weakly-adsorbing configuration to assist accelerator-governed deposition,whereas at strong-convection center,the adsorbate exhibits a mildlyadsorbing configuration to promote leveler-determined inhibition.Deposit profiles can be tailored from dished,flat to domed,depending on predominance of leveler over accelerator.This study should lay theoretical and practical foundations in design and application of copper electroplating additives of multiple adsorbate configurations to cope with complicated interconnect scenarios.展开更多
In order to analyze the effects of forward-swept angle and skin ply-orientation on the static and dynamic aeroelastic characteristics, the aeroelastic modeling and calculation for high-aspect-ratio composite wings wit...In order to analyze the effects of forward-swept angle and skin ply-orientation on the static and dynamic aeroelastic characteristics, the aeroelastic modeling and calculation for high-aspect-ratio composite wings with different forward-swept angles and skin ply-orientation are performed. This paper presents the results of a design study aiming to optimize wings with typical forward-swept angles and skin ply-orientation in an aeroelastic way by using the genetic/sensitivity-based hybrid algorithm. Under the conditions of satiated multiple constraints including strength, displacements, divergence speeds and flutter speeds, the studies are carried out in a bid to minimize the structural weight of a wing with the lay-up thicknesses of wing components as design variabies. In addition, the effects of the power of spanwise variation function of lay-up thicknesses of skins and iugs on the optimized weights are also analyzed.展开更多
A unified structural model for high-aspect-ratio composite wing with arbitrary cross-section is developed. Two types of lay-ups of the composite wing, namely, circumferentially uniform stiffness （CUS） configuration ...A unified structural model for high-aspect-ratio composite wing with arbitrary cross-section is developed. Two types of lay-ups of the composite wing, namely, circumferentially uniform stiffness （CUS） configuration and circumferentially asymmetric stiffness （CAS） configuration, are investigated. The present structural modeling method is validated through ANSYS FEM software for the case of a composite box beam. Then, the case of a single-cell composite wing with NACA0012 airfoil shape is considered. To investigate the aeroelastic problem of high-aspect-ratio composite wings, the linear ONERA aerodynamic model is used to model the unsteady aerodynamic loads under the case of small angle of attack. Finally, flutter speeds of the high-aspect-ratio wing with various composite ply angles are determined by using U-g method.展开更多
The stall flutter characters of high-aspect-ratio composite wing are investigated, and the effects of structure geometric nonlinearity and stiffness couple created by composite anisotropy on them also are discussed. F...The stall flutter characters of high-aspect-ratio composite wing are investigated, and the effects of structure geometric nonlinearity and stiffness couple created by composite anisotropy on them also are discussed. Firstly, the high-aspect-ratio wing is modeled as a composite thin-walled closed section Euler beam whose displacement and rotation both could be of finite value, and the nonlinear dynamic equations is build up on it with all the effects of geometric nonlinearity, aerodynamic nonlinearity and anisotropy of material being considered. Then vibration equations are deduced through perturbing the dynamic equations at wing＇s equilibrium position, and coupled with unsteady stall aerodynamic model and ONERA model, to obtain the nonlinear stall flutter analysis equations of wing. Finally, the flutter stabilities with various wind speeds are determined by the harmonic balance method. With several exampies, the validity of the stall flutter model is proved, and the significant effects of geometric nonlinearity on the stall flutter various characters as wall as the effects of ply angle on the stall flutter speed and frequency also are discussed.展开更多
The two-dimensional equilibrium with flexible boundaries is solved via using a MAT- LAB Equilibrium Code （MEC）, which has applied the finite element method to handle the change- able plasma shape and employed the tr...The two-dimensional equilibrium with flexible boundaries is solved via using a MAT- LAB Equilibrium Code （MEC）, which has applied the finite element method to handle the change- able plasma shape and employed the trust-region dogleg method to solve the nonlinear partial dif- ferential equation. The corresponding driven current profile is also calculated by coupling with the lower-hybrid simulation code （LSC）. The results are applied to optimize the lower hybrid current drive （LHCD） efficiency for the Experimental Advanced Superconductor Tokamak （EAST） and suggested that both elongation and triangularity have a notable effect on the efficiency because of the competition between the increase in the resonant area and in the Shafranov shift. Moreover, large aspect-ratio has a negative effect on the efficiency. These effects are studied numerically, which might be considered carefully for both good plasma confinement and high LHCD efficiency.展开更多
A high-aspect-ratio microchannel heat exchanger based on multi-tool milling process was developed. Several slotting cutters were stacked together for simultaneously machining several high-aspect-ratio microchannels wi...A high-aspect-ratio microchannel heat exchanger based on multi-tool milling process was developed. Several slotting cutters were stacked together for simultaneously machining several high-aspect-ratio microchannels with manifold structures. On the basis of multi-tool milling process, the structural design of the manifold side height, microchannel length, width, number, and interval were analyzed. The heat transfer performances of high-aspect-ratio microchannel heat exchangers with two different manifolds were investigated by experiments, and the influencing factors were analyzed. The results indicate that the magnitude of heat transfer area per unit volume dominates the heat transfer performances of plate-type micro heat exchanger, while the velocity distribution between microchannels has little effects on the heat transfer performances.展开更多
The relationship between stiffness distribution and aeroelastic performance for a beam-frame model and a3-D model is investigated based on aeroelastic optimization of global stiffness design for high-aspect-ratio wing...The relationship between stiffness distribution and aeroelastic performance for a beam-frame model and a3-D model is investigated based on aeroelastic optimization of global stiffness design for high-aspect-ratio wings.The sensitivity information of wing spanwise stiffness distribution with respect to the twist angle at wing tip,the vertical displacement at wing tip,and the flutter speed are obtained using a sensitivity method for both models.Then the relationship between stiffness distribution and aeroelastic performance is summarized to guide the design procedure.By using the genetic/sensitivity-based hybrid algorithm,an optimal solution satisfying the strength,aeroelastic and manufacturing constraints is obtained.It is found that the summarized guidance is well consistent with the optimal solution,thus providing a valuable design advice with efficiency.The study also shows that the aeroelastic-optimization-based global stiffness design procedure can obtain the optimal solution under multiple constraints with high efficiency and precision,thereby having a strong application value in engineering.展开更多
For the strong coupling among the channels of bank-to-turn （BTT） missile with high-aspect-ratio wing, an autopilot is designed with a two loop control structure robust autopilot design methods. By the inner loop des...For the strong coupling among the channels of bank-to-turn （BTT） missile with high-aspect-ratio wing, an autopilot is designed with a two loop control structure robust autopilot design methods. By the inner loop design, the question of pole-zero cancellation is solved, and the stabilization of structured uncertainty is achieved. Through the outer loop of H∞ controller design, the flying performance and robustness can be guaranteed. The nonlinear simulation results show that the autopilot designed has perfect time domain response, and can suppress bad influence of the inertial and kinematics couplings. It can make the missile fly stably in the large flying areas. The control is very effective.展开更多
A high quality of GaAs crystal growth in nanoscale V-shape trenches on Si（O01） substrates is achieved by using the aspect-ratio trapping method. GaAs thin films are deposited via metal-organic chemical vapor deposit...A high quality of GaAs crystal growth in nanoscale V-shape trenches on Si（O01） substrates is achieved by using the aspect-ratio trapping method. GaAs thin films are deposited via metal-organic chemical vapor deposition by using a two-step growth process. Threading disJocations arising from lattice mismatch are trapped by laterally confining sidewalls, and antiphase domains boundaries are completely restricted by V-groove trenches with Si { 111} facets. Material quality is confirmed by scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and high resolution X-ray diffraction. Low temperature photoluminescence （PL） measurement is used to analyze the thermal strain relaxation in GaAs layers. This approach shows great promise for the realization of high mobility devices or optoelectronie integrated circuits on Si substrates.展开更多
Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in ...Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.展开更多
Photocrosslinkable polymers have been exploited to attain impressive advantages in printing freestanding,micrometer-scale,mechanically compliant features.However,a more integrated understanding of both the polymer pho...Photocrosslinkable polymers have been exploited to attain impressive advantages in printing freestanding,micrometer-scale,mechanically compliant features.However,a more integrated understanding of both the polymer photochemistry and the microfabrication processes could enable new strategic design avenues,unlocking far-reaching applications of the light-based modality of additive manufacturing.One promising approach for achieving high-aspect-ratio structures is to leverage the phenomenon of light self-trapping during the photopolymerization process.In this review,we discuss the design of materials that facilitate this optical behavior,the computational modeling and practical processing considerations to achieve high aspect-ratio structures,and the range of applications that can benefit from architectures fabricated using light self-trapping-especially those demanding free-standing structures and materials of stiffnesses relevant in biological applications.Coupled interactions exist among material attributes,including polymer composition,and processing parameters such as light intensity.We identify strong opportunities for predictive design of both the material and the process.Overall,this perspective describes the wide range of existing polymers and additive manufacturing approaches,and highlights various future directions to enable constructs with new complexities and functionalities through the development of next-generation photocrosslinkable materials and micromanufacturing methods.展开更多
基金supported by Key-Area Research and Development Program of Guangdong Province(No.2023B0101040002)National Natural Science Foundation of China(Nos.62304143,52303092 and 62274172)Guangdong Basic and Applied Basic Research Fund(No.2022B1515120037).
文摘Copper metal is widely electroplated for microelectronic interconnections such as redistribution layers(RDL),pillar bumps,through silicon vias,etc.With advances of multilayered RDL,via-on-via structures have been developed for ultrahigh-density any-layer interconnection,which expects superconformal filling of interlayer low aspect-ratio vias jointly with coplanar lines and pads.However,it poses a great challenge to electrodeposition,because current via fill mechanisms are stemming from middle to high aspect-ratio(>0.8)vias and lacking applicability in low aspect-ratio(<0.3)RDL-vias,where via geometry related electric-flow fields coupling must be reconsidered.In the present work,a four-additive strategy has been developed for RDL-vias fill and thoroughly investigated from additive electrochemistry,in situ Raman spectroelectrochemistry,and quantum chemistry perspectives.A novel adsorbate configuration controlled(ACC)electrodeposition mechanism is established that at weak-convection bilateral edges and lower corners,the adsorbate displays a weakly-adsorbing configuration to assist accelerator-governed deposition,whereas at strong-convection center,the adsorbate exhibits a mildlyadsorbing configuration to promote leveler-determined inhibition.Deposit profiles can be tailored from dished,flat to domed,depending on predominance of leveler over accelerator.This study should lay theoretical and practical foundations in design and application of copper electroplating additives of multiple adsorbate configurations to cope with complicated interconnect scenarios.
文摘In order to analyze the effects of forward-swept angle and skin ply-orientation on the static and dynamic aeroelastic characteristics, the aeroelastic modeling and calculation for high-aspect-ratio composite wings with different forward-swept angles and skin ply-orientation are performed. This paper presents the results of a design study aiming to optimize wings with typical forward-swept angles and skin ply-orientation in an aeroelastic way by using the genetic/sensitivity-based hybrid algorithm. Under the conditions of satiated multiple constraints including strength, displacements, divergence speeds and flutter speeds, the studies are carried out in a bid to minimize the structural weight of a wing with the lay-up thicknesses of wing components as design variabies. In addition, the effects of the power of spanwise variation function of lay-up thicknesses of skins and iugs on the optimized weights are also analyzed.
文摘A unified structural model for high-aspect-ratio composite wing with arbitrary cross-section is developed. Two types of lay-ups of the composite wing, namely, circumferentially uniform stiffness （CUS） configuration and circumferentially asymmetric stiffness （CAS） configuration, are investigated. The present structural modeling method is validated through ANSYS FEM software for the case of a composite box beam. Then, the case of a single-cell composite wing with NACA0012 airfoil shape is considered. To investigate the aeroelastic problem of high-aspect-ratio composite wings, the linear ONERA aerodynamic model is used to model the unsteady aerodynamic loads under the case of small angle of attack. Finally, flutter speeds of the high-aspect-ratio wing with various composite ply angles are determined by using U-g method.
文摘The stall flutter characters of high-aspect-ratio composite wing are investigated, and the effects of structure geometric nonlinearity and stiffness couple created by composite anisotropy on them also are discussed. Firstly, the high-aspect-ratio wing is modeled as a composite thin-walled closed section Euler beam whose displacement and rotation both could be of finite value, and the nonlinear dynamic equations is build up on it with all the effects of geometric nonlinearity, aerodynamic nonlinearity and anisotropy of material being considered. Then vibration equations are deduced through perturbing the dynamic equations at wing＇s equilibrium position, and coupled with unsteady stall aerodynamic model and ONERA model, to obtain the nonlinear stall flutter analysis equations of wing. Finally, the flutter stabilities with various wind speeds are determined by the harmonic balance method. With several exampies, the validity of the stall flutter model is proved, and the significant effects of geometric nonlinearity on the stall flutter various characters as wall as the effects of ply angle on the stall flutter speed and frequency also are discussed.
基金supported by National Natural Science Foundation of China (Nos.10975156, 10990214)the fund from Ministry of Science and Technology of China (No.2009GB105002)
文摘The two-dimensional equilibrium with flexible boundaries is solved via using a MAT- LAB Equilibrium Code （MEC）, which has applied the finite element method to handle the change- able plasma shape and employed the trust-region dogleg method to solve the nonlinear partial dif- ferential equation. The corresponding driven current profile is also calculated by coupling with the lower-hybrid simulation code （LSC）. The results are applied to optimize the lower hybrid current drive （LHCD） efficiency for the Experimental Advanced Superconductor Tokamak （EAST） and suggested that both elongation and triangularity have a notable effect on the efficiency because of the competition between the increase in the resonant area and in the Shafranov shift. Moreover, large aspect-ratio has a negative effect on the efficiency. These effects are studied numerically, which might be considered carefully for both good plasma confinement and high LHCD efficiency.
基金Projects(50675070 50805052) supported by the National Nature Science Foundation of China+1 种基金Projects(07118064 8451064101000320) supported by the Natural Science Foundation of Guangdong Province
文摘A high-aspect-ratio microchannel heat exchanger based on multi-tool milling process was developed. Several slotting cutters were stacked together for simultaneously machining several high-aspect-ratio microchannels with manifold structures. On the basis of multi-tool milling process, the structural design of the manifold side height, microchannel length, width, number, and interval were analyzed. The heat transfer performances of high-aspect-ratio microchannel heat exchangers with two different manifolds were investigated by experiments, and the influencing factors were analyzed. The results indicate that the magnitude of heat transfer area per unit volume dominates the heat transfer performances of plate-type micro heat exchanger, while the velocity distribution between microchannels has little effects on the heat transfer performances.
基金supported by the National Natural Science Foundation of China (Nos.11302011,11372023, 11172025)
文摘The relationship between stiffness distribution and aeroelastic performance for a beam-frame model and a3-D model is investigated based on aeroelastic optimization of global stiffness design for high-aspect-ratio wings.The sensitivity information of wing spanwise stiffness distribution with respect to the twist angle at wing tip,the vertical displacement at wing tip,and the flutter speed are obtained using a sensitivity method for both models.Then the relationship between stiffness distribution and aeroelastic performance is summarized to guide the design procedure.By using the genetic/sensitivity-based hybrid algorithm,an optimal solution satisfying the strength,aeroelastic and manufacturing constraints is obtained.It is found that the summarized guidance is well consistent with the optimal solution,thus providing a valuable design advice with efficiency.The study also shows that the aeroelastic-optimization-based global stiffness design procedure can obtain the optimal solution under multiple constraints with high efficiency and precision,thereby having a strong application value in engineering.
文摘For the strong coupling among the channels of bank-to-turn （BTT） missile with high-aspect-ratio wing, an autopilot is designed with a two loop control structure robust autopilot design methods. By the inner loop design, the question of pole-zero cancellation is solved, and the stabilization of structured uncertainty is achieved. Through the outer loop of H∞ controller design, the flying performance and robustness can be guaranteed. The nonlinear simulation results show that the autopilot designed has perfect time domain response, and can suppress bad influence of the inertial and kinematics couplings. It can make the missile fly stably in the large flying areas. The control is very effective.
基金Supported by the National Science and Technology Major Project of China under Grant No 2011ZX02708
文摘A high quality of GaAs crystal growth in nanoscale V-shape trenches on Si（O01） substrates is achieved by using the aspect-ratio trapping method. GaAs thin films are deposited via metal-organic chemical vapor deposition by using a two-step growth process. Threading disJocations arising from lattice mismatch are trapped by laterally confining sidewalls, and antiphase domains boundaries are completely restricted by V-groove trenches with Si { 111} facets. Material quality is confirmed by scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and high resolution X-ray diffraction. Low temperature photoluminescence （PL） measurement is used to analyze the thermal strain relaxation in GaAs layers. This approach shows great promise for the realization of high mobility devices or optoelectronie integrated circuits on Si substrates.
文摘Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.
基金M.Y.acknowledges the Angela Leong Fellowship Fund 2021-2022 from the Massachusetts Institute of Technology.K.K.acknowledges the financial support of the Natural Sciences and Engineering Research Council of Canada(award no.PDF-529703-2019)S.K.acknowledges the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.2019R1A5A8083201 and 2022R1C1C1003966)。
文摘Photocrosslinkable polymers have been exploited to attain impressive advantages in printing freestanding,micrometer-scale,mechanically compliant features.However,a more integrated understanding of both the polymer photochemistry and the microfabrication processes could enable new strategic design avenues,unlocking far-reaching applications of the light-based modality of additive manufacturing.One promising approach for achieving high-aspect-ratio structures is to leverage the phenomenon of light self-trapping during the photopolymerization process.In this review,we discuss the design of materials that facilitate this optical behavior,the computational modeling and practical processing considerations to achieve high aspect-ratio structures,and the range of applications that can benefit from architectures fabricated using light self-trapping-especially those demanding free-standing structures and materials of stiffnesses relevant in biological applications.Coupled interactions exist among material attributes,including polymer composition,and processing parameters such as light intensity.We identify strong opportunities for predictive design of both the material and the process.Overall,this perspective describes the wide range of existing polymers and additive manufacturing approaches,and highlights various future directions to enable constructs with new complexities and functionalities through the development of next-generation photocrosslinkable materials and micromanufacturing methods.
