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In fabricating functional layers, including thin-film transistors and conductive electrodes, using roll-to-roll (R2R) processing on polymer-based PET film, the instability of the slot-die coating meniscus under a high-speed web impedes functional layer formation with the desired thickness and width. The thickness profiles of the functional layers significantly impact the performance of the final products. In this study, we introduce an electrohydrodynamic (EHD)-based voltage application module to a slot-die coater to ensure the uniformity of the cross-machine direction (CMD) thickness profile within the functional layer and enable a stable, high-speed R2R process. The module can effectively control the spreadability of the meniscus by utilizing variations in the surface tension of the ink. The effectiveness of the EHD module was experimentally verified by applying a high voltage to a slot-die coater while keeping other process variables constant. As the applied voltage increases, the CMD thickness deviation reduces by 64.5%, and the production rate significantly increases (up to 300%), owing to the formation of a stable coated layer. The introduction of the EHD-based application module to the slot-die coater effectively controlled the spreadability of the meniscus, producing large-area functional layers. [ABSTRACT FROM AUTHOR]

In order to solve the problem that aluminum coating on bolt surface may be uneven in thickness when aluminum paint was used to coat the bolts, the influence of spraying angle on the uniformity of bolt surface coating is researched in this thesis. Nozzles and bolts of the spraying system were modeled and the computational fluid dynamics simulation software Fluent was used to establish the physical model of the gas-liquid two-phase flow of the atomization flow field. DPM model was used to analyze the interaction between the gas phase and the liquid phase in the flow field. Besides, the spray flow fields at different angles were obtained. The thickness of liquid film deposition on the bolt surface was also predicted and the spraying test system was set up. Results of this research were verified with the simulation results. The simulation and experimental results all show that the bolt surface coating is the most uniform when the spraying angle is 30°. [ABSTRACT FROM AUTHOR]

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thickness nonuniformity is a bottleneck in the micro electroforming process of micro-metal devices. In this paper, a new method of fabricating a layered auxiliary cathode is proposed to improve the thickness uniformity of a micro-electroforming layer. In order to analyze the general applicability of the proposed method, four basic microstructures, namely circular, square, regular triangular, and regular hexagonal were used to study the effect of a layered auxiliary cathode on thickness uniformity through simulation and experimentation. The simulation results showed that with the help of the proposed auxiliary cathode, the thickness nonuniformity of four microstructures should decrease due to the reduced edge effect of the current density. The experimental results showed that the thickness uniformity of four microstructures fabricated via the proposed method was improved by 190.63%, 116.74%, 80.43%, and 164.30% compared to that fabricated via the traditional method, respectively. Meanwhile, the micro-gear was fabricated and the nonuniformity was reduced by 101.15% using the proposed method. [ABSTRACT FROM AUTHOR]

High-speed wafer rotation vertical hot-wall chemical vapor deposition ( CVD) was employed to conduct homeepitaxial growth on n-type 〈1010〉 4° off-angel 4H-SiC wafer. With temperature of 1 650 ℃, pressure of 250 mbar and rotation rate of 600 r/ min, growth rate of over 40. 44 μm/ h was achieved, epi-layer with thickness uniformity of 1. 37% and doping concentration uniformity of 2. 79% was obtained. AFM testing indicates that the surface roughness is 0. 11 nm. Leica microscope indicates that the surface of epilayer is smooth and no macro-step existing, the sharp Raman lines show typical features of 4H-SiC, and defect density is very low. Comprehensive analysis shows that high-quality SiC epilayer is obtained with high growth rate by national high-speed wafer rotation vertical hot-wall CVD equipment. This research provides some guidance for current SiC epitaxial industry development and equipment localization. [ABSTRACT FROM AUTHOR]

In order to improve the thickness uniformity of the electroformed metal layer and components, a new electroforming technique is proposed—wire-anode scanning electroforming (WAS-EF). WAS-EF uses an ultrafine inert anode so that the interelectrode voltage/current is superimposed upon a very narrow ribbon-shaped area at the cathode, thus ensuring better localization of the electric field. The anode of WAS-EF is in constant motion, which reduces the effect of the current edge effect. The stirring paddle of WAS-EF can affect the fluid flow in the microstructure, and improve the mass transfer effect inside the structure. The simulation results show that, when the depth-to-width ratio decreases from 1 to 0.23, the depth of fluid flow in the microstructure can increase from 30% to 100%. Experimental results show that. Compared with the traditional electroforming method, the single metal feature and arrayed metal components prepared by WAS-EF are respectively improved by 15.5% and 11.4%. [ABSTRACT FROM AUTHOR]

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The thickness nonuniformity of an electroformed layer is a bottleneck problem for electroformed micro metal devices. In this paper, a new fabrication method is proposed to improve the thickness uniformity of micro gear, which is the key element of various microdevices. The effect of the thickness of the photoresist on the uniformity was studied by simulation analysis, which showed that as the thickness of the photoresist increased, the thickness nonuniformity of the electroformed gear should decrease due to the reduced edge effect of the current density. Differently from the traditional method performed by one-step front lithography and electroforming, multi-step, self-aligned lithography and electroforming are used to fabricate micro gear structures in proposed method, which intermittently keeps the thickness of photoresist from decreasing during processes of alternate lithography and electroforming. The experimental results show that the thickness uniformity of micro gear fabricated by the proposed method was improved by 45.7% compared with that fabricated by the traditional method. Meanwhile, the roughness of the middle region of the gear structure was reduced by 17.4%. [ABSTRACT FROM AUTHOR]

Uniform wall thickness plays an essential role in avoiding forming failure in incremental sheet forming. However, it is challenging to promote the uniform distribution of wall thickness in single-pass forming of high wall angle and complex three-dimensional thin-walled parts using flexible dieless incremental sheet forming technology. In this article, based on the hydraulic support single-point incremental sheet forming technology, the finite element software is used to simulate and analyze the influence of different support pressure on the wall thickness distribution and the uniform critical angle of single-pass incremental sheet forming truncated pyramid parts. The results show that the hydraulic support can effectively improve the thickness uniformity and critical forming angle. In addition, a single-point increment experiment system of hydraulic support is designed, and the uniform critical angle of wall thickness corresponding to different support pressure is obtained. The experimental results are consistent with the finite element simulation results. Therefore, this article provides guidance for manufacturing high wall angles and complex parts with uniform wall thickness in single-pass incremental sheet forming. [ABSTRACT FROM AUTHOR]

Abstract Background To evaluate the surface quality and thickness uniformity of lamellar donor grafts using an optional surgical technique called reversed manual dissection (RMD) in porcine corneas. Methods Twenty-four paired porcine corneas (48 eyes) were numbered 1 to 24 and divided into 6 groups. All left corneas were assigned to conventional manual dissection (CMD), and all right corneas were assigned to RMD. Each group contained 8 corneas. For Groups I, II, and III, 30, 50, and 70% of the entire corneal thickness was dissected using CMD. For groups IV, V, and VI, 70, 50, and 30% of the entire corneal thickness was dissected using RMD. The residual stromal thickness was examined by anterior segment optical coherence tomography (ASOCT) to assess the thickness uniformity and scanning electron microscopy (SEM) to assess the surface quality. Results The thickness uniformity of the lamellar grafts between each paired group was not significantly different (p > 0.05). The qualitative surface roughness grading (QiSR) evaluated by masked observers through SEM was significantly higher in the RMD groups (p

Thickness nonuniformity is a bottleneck in the micro electroforming process of micro-metal devices. In this paper, a new method of fabricating a layered auxiliary cathode is proposed to improve the thickness uniformity of a micro-electroforming layer. In order to analyze the general applicability of the proposed method, four basic microstructures, namely circular, square, regular triangular, and regular hexagonal were used to study the effect of a layered auxiliary cathode on thickness uniformity through simulation and experimentation. The simulation results showed that with the help of the proposed auxiliary cathode, the thickness nonuniformity of four microstructures should decrease due to the reduced edge effect of the current density. The experimental results showed that the thickness uniformity of four microstructures fabricated via the proposed method was improved by 190.63%, 116.74%, 80.43%, and 164.30% compared to that fabricated via the traditional method, respectively. Meanwhile, the micro-gear was fabricated and the nonuniformity was reduced by 101.15% using the proposed method.

Boron as thin film material is of relevance for use in modern micro- and nano-fabrication technology. In this research boron thin films are realized by a number of physical and chemical deposition methods, including magnetron sputtering, electron-beam evaporation, plasma enhanced chemical vapor deposition (CVD), thermal/non-plasma CVD, remote plasma CVD and atmospheric pressure CVD. Various physical, mechanical and chemical characteristics of these boron thin films are investigated, i.e., deposition rate, uniformity, roughness, stress, composition, defectivity and chemical resistance. Boron films realized by plasma enhanced chemical vapor deposition (PECVD) are found to be inert for conventional wet chemical etchants and have the lowest amount of defects, which makes this the best candidate to be integrated into the micro-fabrication processes. By varying the deposition parameters in the PECVD process, the influences of plasma power, pressure and precursor inflow on the deposition rate and intrinsic stress are further explored. Utilization of PECVD boron films as hard mask for wet etching is demonstrated by means of patterning followed by selective structuring of the silicon substrate, which shows that PECVD boron thin films can be successfully applied for micro-fabrication. [ABSTRACT FROM AUTHOR]

Background: To evaluate the surface quality and thickness uniformity of lamellar donor grafts using an optional surgical technique called reversed manual dissection (RMD) in porcine corneas.Methods: Twenty-four paired porcine corneas (48 eyes) were numbered 1 to 24 and divided into 6 groups. All left corneas were assigned to conventional manual dissection (CMD), and all right corneas were assigned to RMD. Each group contained 8 corneas. For Groups I, II, and III, 30, 50, and 70% of the entire corneal thickness was dissected using CMD. For groups IV, V, and VI, 70, 50, and 30% of the entire corneal thickness was dissected using RMD. The residual stromal thickness was examined by anterior segment optical coherence tomography (ASOCT) to assess the thickness uniformity and scanning electron microscopy (SEM) to assess the surface quality.Results: The thickness uniformity of the lamellar grafts between each paired group was not significantly different (p > 0.05). The qualitative surface roughness grading (QiSR) evaluated by masked observers through SEM was significantly higher in the RMD groups (p < 0.001). The quantitative surface roughness grading (QnSR) acquired from the Mountains software was significantly lower in the RMD groups (p < 0.001).Conclusions: RMD is an optional surgical technique for obtaining porcine lamellar grafts. The thickness uniformity of RMD is comparable to that of CMD, and a smoother surface with fewer ridges and roughness is achieved compared to CMD. [ABSTRACT FROM AUTHOR]

In order to improve the thickness uniformity of the electroformed metal layer and components, a new electroforming technique is proposed—wire-anode scanning electroforming (WAS-EF). WAS-EF uses an ultrafine inert anode so that the interelectrode voltage/current is superimposed upon a very narrow ribbon-shaped area at the cathode, thus ensuring better localization of the electric field. The anode of WAS-EF is in constant motion, which reduces the effect of the current edge effect. The stirring paddle of WAS-EF can affect the fluid flow in the microstructure, and improve the mass transfer effect inside the structure. The simulation results show that, when the depth-to-width ratio decreases from 1 to 0.23, the depth of fluid flow in the microstructure can increase from 30% to 100%. Experimental results show that. Compared with the traditional electroforming method, the single metal feature and arrayed metal components prepared by WAS-EF are respectively improved by 15.5% and 11.4%.

Uniform wall thickness plays an essential role in avoiding forming failure in incremental sheet forming. However, it is challenging to promote the uniform distribution of wall thickness in single-pass forming of high wall angle and complex three-dimensional thin-walled parts using flexible dieless incremental sheet forming technology. In this article, based on the hydraulic support single-point incremental sheet forming technology, the finite element software is used to simulate and analyze the influence of different support pressure on the wall thickness distribution and the uniform critical angle of single-pass incremental sheet forming truncated pyramid parts. The results show that the hydraulic support can effectively improve the thickness uniformity and critical forming angle. In addition, a single-point increment experiment system of hydraulic support is designed, and the uniform critical angle of wall thickness corresponding to different support pressure is obtained. The experimental results are consistent with the finite element simulation results. Therefore, this article provides guidance for manufacturing high wall angles and complex parts with uniform wall thickness in single-pass incremental sheet forming.

The thickness nonuniformity of an electroformed layer is a bottleneck problem for electroformed micro metal devices. In this paper, a new fabrication method is proposed to improve the thickness uniformity of micro gear, which is the key element of various microdevices. The effect of the thickness of the photoresist on the uniformity was studied by simulation analysis, which showed that as the thickness of the photoresist increased, the thickness nonuniformity of the electroformed gear should decrease due to the reduced edge effect of the current density. Differently from the traditional method performed by one-step front lithography and electroforming, multi-step, self-aligned lithography and electroforming are used to fabricate micro gear structures in proposed method, which intermittently keeps the thickness of photoresist from decreasing during processes of alternate lithography and electroforming. The experimental results show that the thickness uniformity of micro gear fabricated by the proposed method was improved by 45.7% compared with that fabricated by the traditional method. Meanwhile, the roughness of the middle region of the gear structure was reduced by 17.4%.

Smooth surface morphology and high thickness uniformity heteroepitaxy of corundum-structured (α-) gallium oxide (Ga 2 O 3) crystalline thin films on 100-mm diameter c -plane sapphire substrates were successfully demonstrated using vertical hot-wall mist chemical vapor deposition (CVD). The growth rate and surface morphology of the epitaxial layers were numerically and experimentally found to be dependent on the diameter of the precursor-diluted microdroplets approaching the substrate surface. Since the microdroplet is gradually evaporated while traveling through the furnace, the growth variables such as temperature, mist-flow velocity, and substrate position were tuned to obtain a suitable diameter of microdroplets approaching the substrate. In this study, the diameter of the approaching microdroplet was ≈2 μm, which was optimal for the smooth surface (root mean square roughness ≈1 nm) of α -Ga 2 O 3 epitaxial layers with a growth rate of ≈230 nm/h. Due to the even flow of mist in the vertical furnace, high thickness uniformity of the α -Ga 2 O 3 epitaxial layer is guaranteed on large-scale substrates, with a standard deviation of thickness as small as 28 nm, paving the way for highly reliable Ga 2 O 3 -based electric and optoelectronic devices. [ABSTRACT FROM AUTHOR]

A new approach to precision electroforming of a wafer scale nickel shim using a rotating cathode with an auxiliary cathode mask is developed to improve thickness uniformity and flatness. The effects of critical process parameters, including cathode rotating speed, cathode mask size, and current density, on the thickness uniformity and flatness of electroformed nickel shim are systematically studied based on experiments and simulations. The results show that the thickness uniformity of the deposits is highly dependent on the current density distribution, where a cathode mask can effectively tune electrical field lines and induce a more uniform current density distribution. The simulations and experimental results consistently agree that a minimum thickness nonuniformity of 8% and below 1% on the wafer with a diameter of 80 mm and 40 mm, respectively, can be achieved using a mask with a 70 mm opening size. However, for flatness, the cathode rotating speed influences the surface warpage due to the intrinsic stress. It is also found that the gradient current density can significantly reduce the intrinsic stress with better flatness. The best flatness is controlled below 47 µm and 32 µm on the wafer with diameters of 80 mm and 40 mm, respectively, under the synergistic effect of optimal cathode rotating speed (30 rpm) and gradient current density. [ABSTRACT FROM AUTHOR]

To improve the thickness uniformity of sheet metal parts in incremental forming method based on a virtual auxiliary body, the effect of relevant parameters on the thickness uniformity was studied from both overall and local perspectives. Finite element (FE) method was used to carry out the single-factor and two-level factorial experiments, in which standard deviation of the thickness of section nodes was used as a response to analyzing the effect of factors on the thickness uniformity. First, the mean effects of each factor were obtained and the factor levels of factorial experiments were determined through a single-factor experiment. Then, the interaction effect between factors was analyzed and the optimal combination of parameters was determined through factorial experiments. From the FE analysis, it was found that the desired forming angle and the gap at the bottom have obvious mean effects and interactional effects on the thickness uniformity. Finally, the initial and optimal parameters were used for forming experiments. In the forming experiments, the overall and local thickness standard deviations of section nodes were reduced from 0.194 to 0.088 mm and from 0.149 to 0.081 mm, respectively, which means that the optimized parameters can effectively improve the thickness uniformity of sheet metal parts. [ABSTRACT FROM AUTHOR]

Featured Application: This paper presents a stretching process of a metal sheet with a variable thickness. It gives products with better performances than that with constant thickness. This work presents a finite element model to analyze the distribution of the strains due to an axisymmetric stretching of a metal sheet. The sheet is characterized by a variable initial thickness. The resulting strain state is compared with that of a sheet with a constant initial thickness. The results of the present study allow asserting that the distribution of strains in the sheet can be controlled by setting opportunely the trend of the sheet initial thickness. In this way, it is possible to see that, starting from a sheet with variable initial thickness, a lighter final product is obtained, whose final thickness distribution is more uniform than that of the product obtained from a classic stretching process that requires a sheet with constant initial thickness. Encouraging results from an experimental activity carried out on an AA6060 aluminum alloy sheet, whose trend of initial thicknesses was prepared by removing material from a commercial sheet with a constant thickness, allow us to note the good agreement with what was theoretically highlighted. [ABSTRACT FROM AUTHOR]

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the CNC incremental forming, the forming quality will be different with the different extrusion direction. The effects of the different extrusion directions on the forming quality in the CNC incremental forming with the multidirectional adjustment of sheet postures were studied by using three extrusion directions: parallel to the Z-axis, perpendicular to sheet surface and perpendicular to the surface to be formed. The algorithm for calculating the inclination angle of the extrusion tool and determining the extrusion direction vector in the multidirectional adjustment environment of sheet postures was presented. The feasibility of the algorithm was verified by an application example. The equivalent plastic strains under the three extrusion directions were analyzed through the numerical simulation. At the same time, the contour accuracy, thickness reduction and thickness distribution were compared and analyzed through the CNC incremental forming experiment with the multidirectional adjustment of sheet postures under the three extrusion directions. [ABSTRACT FROM AUTHOR]

The electrodeposition of copper foil with thorough holes was simulated using Comsol Multiphysics software. The effects of flow rate of electrolyte and current density on the distribution of copper ions, as well as the effects of current density and interelectrode spacing on the thickness uniformity of copper foil were studied. The simulation results showed that the circulation of electrolyte makes copper ions distribute well, which is beneficial to the electrodeposition of copper foil. The thickness uniformity of copper foil could be improved by distributing pores in an annular array or increasing the interelectrode spacing. The simulation results of the model were in a good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

In all animals, the hide mass increases together with live body weight. At the age of 6 months and 3 years, the total weight of yak hide is almost two times higher than in other cattle. At 6 months, the thickness of yak hide in all topographical points exceeds that of cowhide by almost two times. By one and three years, the difference in the reference point disappears. However, the neck and the bellous hides of yak remain 25–40% thicker, and the skin area of other breeds of cattle exceeds that of yak at all ages by 35–40%. For the yaks of the Aininks Region, the optimal hide removal period is from birth to 3–4 years. For the animals over 4 years old, the hide yield by weight becomes relatively low. As far as thickness uniformity is concerned, the best skins for leather processing are those obtained from yaks under 3 years old, since they have the lowest degree of slackness. As for the chemical composition, the moisture of yak hide is 2.0–2.5% higher and the hide substance is 7.0–18.5% lower than in cowhide. This is, probably, connected with a certain reserve of water, or the so-called «depot moisture», in the skin of the animal. For all age periods, the moisture of the bellous yak hides is lower and fat content is by 1.5–2.2% higher than in other topographical areas. Apparently, this is due to the thermal adaptation of animals to the habitat conditions.

To solve the problem of the uneven thickness distribution of a formed part caused by a large difference between the forming angles and the different curvatures of the surfaces in CNC incremental forming, a combinatorial optimization method of multidirectional sheet postures was proposed based on particle swarm optimization. In this method, an infinite number of optional sheet postures at each point in the forming area are taken as the combined object. The optimization goal is to make the forming angles of the entire sheet part be smaller than the forming limit angle and to minimize the difference between them; then find the optimal combination of the multidirectional sheet postures that can be selected at each point in the forming area. Case studies of the algorithm and the actual forming experiment show that not only can the optimized multidirectional sheet metal postures determined by the proposed method realize the non-fracture forming of the sheet metal parts with different forming angles and different curvature of the surface, but also obtain a more uniform thickness distribution of the formed parts. [ABSTRACT FROM AUTHOR]

RGB printing method has been widely regarded as a potential tool for manufacturing high resolution, large size OLED applications, with the help of recent progresses of soluble OLED materials and ink‐jet printing equipment. However, there are still technical hurdles which remain in order for inkjet‐printed OLED displays to move from prototype to mass production scale. In this report, recent R&D trends will be reviewed of device performances, ink‐jet printing equipment, as well as inkjet‐printed OLED products recently demonstrated by display panel makers for various applications. Moreover, key technical issues will be discussed to be overcome in order for mass production, such as an ink formulation, a high resolution ink‐jet printing, inter‐mixing between printed layers, thickness uniformity of printed layers, etc. Lastly, our recent progress will be presented, of a power consumption, color gamut, and lifetime of inkjet‐printed panel with pixel resolution over 200ppi. [ABSTRACT FROM AUTHOR]

The limits of a sheet metal stretching process are mainly two: i) it determines tears in a little formable material; ii) it produces a non-uniform thickness distribution in the formed component. For this reason, this work presents encouraging preliminary experimental results on a stretching process of an aluminium alloy sheet that has a variable thickness. This sheet was machined by removing material from a commercial sheet of constant thickness. The obtained results show how the use of a sheet with a variable thickness allows to increase the material formability and to manufacture a product characterized by a more uniform thickness. [ABSTRACT FROM AUTHOR]

We herein report the effect of the viscosity of a prepolymer solution on the thickness uniformity of silver-nanowire-embedded flexible transparent electrodes. We adopted a model system with all the prepolymer solutions possessing identical physical properties except for the viscosity and then explored the most common prepolymer solutions for silver-nanowire-embedded flexible electrodes. In all experiments, single-step spin coating was conducted to coat the prepolymer solution on silver nanowires. We found that the electrodes were thinner for lower viscosity. However, the thickness ratio between the center and edge was comparable (50–60%) and independent of the prepolymer solution viscosity. This indicates that the viscosity does not determine the thickness uniformity, and that the coating method itself is vital to obtain films with uniform thickness. The flexible electrodes were introduced into organic solar cells. Their device performance was comparable regardless of the position of the electrodes and their thickness. This is because the thickness difference of the flexible electrodes did not affect their transmittance significantly. Thus, we conclude that although different coating approaches are needed to obtain flexible electrodes with high uniformity, the performance of optoelectronic devices on silver-nanowire-embedded flexible electrodes is independent of them. [ABSTRACT FROM AUTHOR]

Serious concentration polarization occurs during the electroplating of metal waveguide cavity due to the extremely small space inside, leading to nonuniform thickness distribution of coating. A flow guiding device was used to accelerate the flow and exchange of solution in metal waveguide cavity during gold electroplating. The gold coating obtained therewith featured uniform thickness distribution above 1 μm. [ABSTRACT FROM AUTHOR]

This work presents a finite element model to analyze the distribution of the strains due to an axisymmetric stretching of a metal sheet. The sheet is characterized by a variable initial thickness. The resulting strain state is compared with that of a sheet with a constant initial thickness. The results of the present study allow asserting that the distribution of strains in the sheet can be controlled by setting opportunely the trend of the sheet initial thickness. In this way, it is possible to see that, starting from a sheet with variable initial thickness, a lighter final product is obtained, whose final thickness distribution is more uniform than that of the product obtained from a classic stretching process that requires a sheet with constant initial thickness. Encouraging results from an experimental activity carried out on an AA6060 aluminum alloy sheet, whose trend of initial thicknesses was prepared by removing material from a commercial sheet with a constant thickness, allow us to note the good agreement with what was theoretically highlighted.

Optical polyimide (PI) films were prepared by spin-coating from nearly non-volatile dimethylacetamide (DMAc) solutions. The uniformity of film thickness met the requirements of diffraction imaging quality. The results show that the final rotating speed ω, dynamic viscosity η, and initial polymer solid concentration c are the main factors affecting the film thickness T, and an empirical relationship which describes the film thickness as a function of the measured parameters was established to be T ∝ c 3.473 , η 0.586 , ω − 0.811. $T \propto {c^{3.473}},{\rm{ }}{\eta ^{0.586}},{\rm{ }}{\omega ^{ - 0.811}}.$ Moreover, the viscosity dependence on concentration is system specific. Unlike traditional photoresist, the thickness uniformity of the PI film is determined by both spinning and precure process, which is intensively discussed in the present work. Uniform, 22-μm thick, PI films with transmitted wavefronts peak to valley (PV) ≤ 1/5 λ and root mean square (RMS) ≤ 1/50 λ were prepared under the optimum process: spin speed 900 rpm, initial fluid viscosity 10,500 cp, final spin time 120 s, precure temperature 70°C, spin process repeated 3 times. The results will find use in the production of optical quality membrane for ultra-lightweight optics or other applications. [ABSTRACT FROM AUTHOR]

Highlights • Effect of substrate surface roughness on thickness uniformity of complex GLC coatings was studied. • Thickness uniformity of GLC coating was improved by the introduction of element Y. • The number of elements Y, Ce and Ta inserts were optimized to obtain uniform thickness distribution. • Vibration attenuation was obtained by depositing uniform complex GLC coating on the gear. Abstract In this paper, the effects of substrate surface roughness and the addition of yttrium, cerium and tantalum on thickness uniformity of graphite-like carbon (GLC) coatings on gears were studied by magnetron sputtering method using mosaic targets. And noise reduction effects of gear pump deposited with complex GLC coatings were evaluated at different rotate speeds. The results showed that target-substrate distance, sputtering angle and surface roughness had influences on thickness uniformity of GLC coatings on gear. The introduction of elements Y, Ce and Ta into GLC coatings could effectively improve their thickness uniformity. The complex GLC coating with optimal thickness uniformity on gear exhibited significantly reduction effect for gear noise and the reduction effect for axial vibration was better than that of radial vibrations. Compared with uncoated gears, the noise for the coated gears was decreased by 10 dB at 2000 rpm. Good high-frequency noise reduction was obtained, which could be decreased by 19 dB in the range of 4000–10,000 Hz. [ABSTRACT FROM AUTHOR]

We herein report the effect of the viscosity of a prepolymer solution on the thickness uniformity of silver-nanowire-embedded flexible transparent electrodes. We adopted a model system with all the prepolymer solutions possessing identical physical properties except for the viscosity and then explored the most common prepolymer solutions for silver-nanowire-embedded flexible electrodes. In all experiments, single-step spin coating was conducted to coat the prepolymer solution on silver nanowires. We found that the electrodes were thinner for lower viscosity. However, the thickness ratio between the center and edge was comparable (50−60%) and independent of the prepolymer solution viscosity. This indicates that the viscosity does not determine the thickness uniformity, and that the coating method itself is vital to obtain films with uniform thickness. The flexible electrodes were introduced into organic solar cells. Their device performance was comparable regardless of the position of the electrodes and their thickness. This is because the thickness difference of the flexible electrodes did not affect their transmittance significantly. Thus, we conclude that although different coating approaches are needed to obtain flexible electrodes with high uniformity, the performance of optoelectronic devices on silver-nanowire-embedded flexible electrodes is independent of them.

The spray painting robots with mounted electrostatic rotating bell (ESRB) atomizers have been widely used to maintain high painting quality for various car models in rapid automotive production. The focus of this study is on developing the optimum coating path pitch while considering automobile painting quality. We define a deposition model optimized for the ESRB atomizer and introduce a method to optimize the path pitch with a cost function for painting thickness uniformity, which plays an important role in painting quality. In addition, experimental results are presented to verify the validity of the optimal path pitch simulation results. By using the results of this study, it is possible to improve the painting quality and thus the productivity of spray painting robots. [ABSTRACT FROM AUTHOR]

An evaluation method for the stretchability of a biaxially oriented film during the stretching process was recently developed using an in situ measurement test machine. Stress, retardation, three-dimensional refractive indexes, light-scattering image, and birefringence distribution of films could be obtained in a short time. This stretching test machine was applied to examine the film stretchability of both semicrystalline polymers, such as polypropylene, and noncrystalline polymers, such as polystyrene, under various preheating times. From the measurements, the stress of semicrystalline polymers increased with increasing preheating times before stretching the film. However, the stress of noncrystalline polymers did not increase with increasing preheating times. This means that semicrystalline polymer is required to set up an optimum stretching condition of the preheating time for a satisfactory biaxially oriented film. Furthermore, the birefringence distribution and thickness uniformity of the stretched film were measured simultaneously. It was found that the stretchability of polypropylene and polystyrene films could be evaluated with a small piece of the sample using the biaxial stretching test machine. [ABSTRACT FROM AUTHOR]

Large-scale graphitic thin film with high thickness uniformity needs to be developed for industrial applications. Graphitic films with thicknesses ranging from 3 to 20 nm have rarely been reported, and achieving the thickness uniformity in that range is a challenging task. In this study, a process for growing 20 nm-thick graphite films on Ni with improved thickness uniformity is demonstrated and compared with the conventional growth process. In the film grown by the process, the surface roughness and coverage were improved and no wrinkles were observed. Observations of the film structure reveal the reasons for the improvements and growth mechanisms. [ABSTRACT FROM AUTHOR]

• The whole process of magnetron sputtering is calculated and simulated. The fractal theory is used to explain the quality of coating film. • Titanium polypropylene film was prepared by magnetron sputtering instrument. • The COMSOL simulation and Matlab calculation are carried out, and the experimental results are combined with the simulation results. • The corresponding relation between target base distance and film thickness is obtained through calculation and experiment. In this work, the whole process of physical vapor deposition, including the generation, migration and deposition of sputtering atoms, has been calculated and simulated. In order to verify the reliability of the simulation, the experiment and simulation are combined. In this paper, titanium was deposited on the surface of polypropylene plate. Raman scanning electron microscopy (SEM) and environmental controlled atomic force microscopy (EAFM) were used to characterize the surface morphology, elemental composition and surface roughness of titanized polypropylene. At the same time, the fractal dimension after wavelet analysis is used to describe the surface morphology and growth state of the film. The simulation results show that the sputtering target base distance, sputtering current and sputtering time have great influence on the film forming quality. The experimental results show that the target base distance is negatively correlated with the film formation thickness, while the sputtering current and sputtering time are positively correlated with the film formation thickness. The modified film has uniform surface thickness and smooth shape. This is consistent with the description of fractal theory after wavelet analysis. [ABSTRACT FROM AUTHOR]

A hot-press tackified preform was used to improve the uniformity of the laminates thickness and the mechanical properties of the obtained laminates were studied using vacuum assisted resin transfer molding (VARTM). Two modified preforms were prepared under 0.1 and 0.6 MPa in an autoclave and then were used to fabricate the laminates via VARTM. Permeability and thickness distribution of the laminates were obtained by using a special device. Moreover, the tensile and compressive strengths of the obtained laminates were studied and compared with the unmodified ones. Results show that the tackified laminates present a maximum and minimum thickness under 0.1 and 0.6 MPa, respectively. The thicknesses and in-plane permeability of the tackified laminates, with better thickness uniformity, are significantly decreased compared with that of the unmodified cases, while the tensile and compressive strengths of the tackified laminates are improved obviously. Results show that the mechanical property of the tackified laminates prepared by hotpressing at 0.1 MPa is better than that processed at 0.6 MPa. [ABSTRACT FROM AUTHOR]

This study examines the solution for one of the most difficult problems of electroforming process “thickness deviation”. As an effective solution, an auxiliary electrode (dummy cathode) is considered. Generally, the thickness of an edge plating area is almost twice the center area or greater. An auxiliary electrode (intentionally attached dummy cathode) has helped to achieve more uniform thickness of the electroformed-nickel layer by preventing excessive electric charge. In addition, computer-aided analysis was performed to determine the optimal condition of electroforming process and to confirm the experimental result.

Here, we present the spectroscopic ellipsometry investigation of synthetically grown wafer-scale two-dimensional (2D) MoS 2 and WSe 2 films to access quality and thickness uniformity. MoS 2 and WSe 2 samples were grown by chemical vapor deposition and atomic layer deposition, respectively. Complex dielectric function ( ε = ε 1 + i ε 2 ) and thickness information of these 2D films were extracted from the measured data using multilayer optical calculations. Broad spectral range (1.2–6 eV) and multiple angles of incidence were used to reduce correlations among fitting parameter. Lineshape of ε of MoS 2 and WSe 2 monolayer films are consistent with literature but shows higher values, suggests better quality of our samples. Eight-inch wafer size MoS 2 monolayer sample shows ∼ 70% uniformity with an average thickness of 0.65 ± 0.2 nm, and three-layer WSe 2 sample of 8 × 1 cm 2 area shows ∼ 80% uniformity with an average thickness of 2.5 ± 0.4 nm. Our results will be helpful to accelerate commercialization process of 2D devices. [ABSTRACT FROM AUTHOR]

A roll-to-roll (R2R) thermal evaporation system was developed to manufacture low-cost flexible OLEDs. A vacuum-compatible bottom-up thermal evaporation method was adopted to ensure the quality and the stability of the thin film. DSMC (Direct Simulation Monte Carlo) simulation was used to predict the CD (Cross Direction) uniformity of the thickness of the deposited thin film. And, a uniformity-compensation method using the Z-map algorithm was developed to realize entire uniformity on a continuous roll-to-roll scan-type substrate. An experimental investigation confirms that these simulations fit the actual test results well. And, a flexible OLED lighting sample could be fabricated using the proposed method and the developed R2R equipment. These results represent a meaningful step towards the production of low-cost flexible OLED applications [ABSTRACT FROM AUTHOR]

Nanotwinned (nt) Cu has received much attention because of its superior mechanical and electrical properties, but only a few production processes can yield nt-Cu parts with uniform thickness and a homogeneous microstructure on the wafer scale. To solve this problem, a new precision electroforming process is proposed that combines auxiliary cathodes with pulse reverse current (PRC) electroforming, which provides a synergistic effect to increase the homogeneity of the thickness and a nanoscale twin structure. As a practical example of the proposed process, 4-inch nt-Cu lamina arrays were fabricated and numerically modeled to probe into the synergistic mechanisms. The intrinsic correlations among the array element spacing, current waveform, and main forms of thickness nonuniformity were determined. In addition, the effects of the processing parameters on the microstructural evolution and microhardness of the nt-Cu arrays were analyzed. The results indicated that such a significant improvement in thickness uniformity and microstructure homogeneity were due to the auxiliary-cathode/PRC combination, which enables maximization of the PRC leveling efficiency by inducing a uniform current distribution; this effectively ensures that the microstructures are uniform across all laminae on the wafer scale. Additionally, thick nt-Cu deposited on the current-crowding regions was preferentially stripped during the application of reverse current. This alleviates the adverse effects of the current redistribution resulting from the auxiliary cathode on the thickness uniformity of the laminae and offers additional possibilities for homogeneous growth of nt-Cu. The new precision electroforming process has significant potential to produce wafer-scale components with uniform thickness and specific microstructures. [Display omitted] • A new precision electroforming process based on the combination of auxiliary cathode and pulse reverse current is proposed. • The process can fabricate wafer-scale array components with uniform thickness and homogeneous microstructures. • Numerical simulation and experimental studies highlighted the synergistic mechanisms controlling the thickness and microstructure. • The process maximizes the leveling efficiency while minimizing the current-redistribution problems caused by the auxiliary cathode. • The relationship between processing parameters, thickness distribution, microstructure, and microhardness were established. [ABSTRACT FROM AUTHOR]