Electroforming Technology Research Articles

Jet Electroforming of High-Aspect-Ratio Microcomponents by Periodically Lifting a Necked-Entrance Through-Mask.

High-aspect-ratio micro- and mesoscale metallic components (HAR-MMMCs) can play some unique roles in quite a few application fields, but their cost-efficient fabrication is significantly difficult to accomplish. To address this issue, this study proposes a necked-entrance through-mask (NTM) periodically lifting electroforming technology with an impinging jet electrolyte supply. The effects of the size of the necked entrance of the through-mask and the jet speed of the electrolyte on electrodeposition behaviors, including the thickness distribution of the growing top surface, deposition defect formation, geometrical accuracy, and electrodeposition rate, are investigated numerically and experimentally. Ensuring an appropriate size of the necked entrance can effectively improve the uniformity of deposition thickness, while higher electrolyte flow velocities help enhance the density of the components under higher current densities, reducing the formation of deposition defects. It was shown that several precision HAR-MMMCs with an AR of 3.65 and a surface roughness (Ra) of down to 36 nm can be achieved simultaneously with a relatively high deposition rate of 3.6 μm/min and thickness variation as low as 1.4%. Due to the high current density and excellent mass transfer effects in the electroforming conditions, the successful electroforming of components with a Vickers microhardness of up to 520.5 HV was achieved. Mesoscale precision columns with circular and Y-shaped cross-sections were fabricated by using this modified through-mask movable electroforming process. The proposed NTM periodic lifting electroforming method is promisingly advantageous in fabricating precision HAR-MMMCs cost-efficiently.

Development of electroforming technology for flexible metal substrates for high-efficiency double-sided electronic devices

In this study, we investigate a novel material that surpasses conventional concepts used for substrate materials in flexible electronic devices. Unlike traditional materials, this novel material can replace polymers with a metallic substance. This substance is capable of supporting electronic devices on both sides. Our development focuses on a metallic substrate material based on Fe-Ni. This material allows for the implementation of secondary batteries on its extremely flat opposite side through the electroforming method. The Fe (Iron)-Ni (Nickel) material produced by electroforming shows superior characteristics in terms of coefficient of thermal expansion (CTE) and mechanical properties. This superiority is due to its finer grain size, compared to Fe-Ni produced by the rolling process. Furthermore, when we use the Fe-Ni material to manufacture secondary batteries, it demonstrates equivalent or superior battery characteristics compared to the conventional aluminum (Al) collector material. During thermal shock tests, the Fe-Ni material also shows superior adhesion compared to the traditional Al collector. This advantage is attributed to Fe-Ni's low CTE. Our approach enables the implementation of secondary batteries for power generation on one side and the manufacture of electronic components for power consumption on the other. This creates a new concept for flexible substrate materials.

An overview of friction stir processing of Cu–SiC composites: Microstructural, mechanical, tribological, and electrical properties

Copper matrix composite reinforced with SiC exhibits high electrical and thermal conductivity, as well as superior mechanical properties, making it a potential candidate for thermal management applications. There has been rapid progress in the understanding of Cu–SiC metal matrix composites during the past decade. To accomplish this, powder metallurgy, casting, selective laser melting, composite electroforming technology, and electrodeposition methods have been employed. The optimum cutting conditions for fabrication of Cu–SiC metal matrix composites are still being explored. In recent years, friction stir processing (FSP) has become increasingly popular in the fabrication of composites. FSP is capable of microstructural engineering in Cu–SiC systems. In light of the fact that the electrical/thermal conductivity and mechanical performance of Cu–SiC composites depend on microstructural characteristics such as SiC distribution, grain size, grain orientation, density of dislocations, and bulk density, it seems important to study the effect of manufacturing conditions on microstructure in detail. In this study, the influence of FSP parameters such as rotational and traversal speeds, the number of FSP passes, and the pin profile as well as the characteristics of SiC powder are discussed in detail with regard to macro- and microstructure, hardness, strength, tribological, and electrical properties of FSPed Cu–SiC composites.

Filter for Cell Trapping by Precision Electroforming Technology

Filter for Cell Trapping by Precision Electroforming Technology

Coexistent improvement of thermal and mechanical performance at Si/Cu joint by thickness-controlled Sn-Ag bond layer

In this study, sound Si-Cu joints with high thermal conductivity and mechanical property were achieved at 260 °C with thickness-controlled Sn-Ag bond layer. The microstructure evolution, thermal and mechanical properties were proposed systematically. The bond layer was fabricated by micro electroforming technology to precisely control the thickness and improve the bond ability. The electroformed Ag layer could protect the sputtered Cu film and restrict the diffusion of Cu elements, which could decrease the residual stress and remove the interface defects. At the joints, the electroformed Sn layer was consumed to form Ag3Sn and Cu6Sn5 intermetallic compounds. The thermal conductivity and shear strength both increased firstly and then decreased with the thickness of bond layer increasing. The highest thermal conductivity of 283.21 W/(m·K) and shear strength of 88.74 MPa were achieved synchronous with 15-μm-thickness Sn-Ag bond layers, which were attributed to the reduction of the interface stress and elimination of interfacial defects. This technology had potential to be applied in the microelectronic heat dissipation at the future.

The implementation of electroforming technology on home industry and souvenir center in Malang

Souvenir industry is the supporting aspect of tourism industry. As the one of creative economy industries, souvenir shows the characteristics of a region or a tourism place. This industry needs expertise and creativity, but there is an issue in the development of product variations with high expenses and the improvement of skills to create a product. The method to conduct this program is by conducting empowerment with participative and bottom-up approach. The participants are given electroforming training for souvenir industry. From the implementation of this program, the souvenir industry is given assistance through the training of electroforming technology to improve their creativity and souvenir production.Souvenir industry is the supporting aspect of tourism industry. As the one of creative economy industries, souvenir shows the characteristics of a region or a tourism place. This industry needs expertise and creativity, but there is an issue in the development of product variations with high expenses and the improvement of skills to create a product. The method to conduct this program is by conducting empowerment with participative and bottom-up approach. The participants are given electroforming training for souvenir industry. From the implementation of this program, the souvenir industry is given assistance through the training of electroforming technology to improve their creativity and souvenir production.

Fabrication of Three-Dimensionally Deformable Metal Structures Using Precision Electroforming.

It is difficult to fabricate three-dimensional structures using semiconductor-process technology, because it is based on two-dimensional layered structure fabrication and the etching of thin films. In this study, we fabricated metal structures that can be dynamically deformed from two-dimensional to three-dimensional shapes by combining patterning using photolithography with electroforming technology. First, a resist structure was formed on a Cu substrate. Then, using a Ni sulfamate electroforming bath, a Ni structure was formed by electroforming the fabricated resist structure. Finally, the resist structure was removed to release the Ni structure fabricated on the substrate, and electroforming was used to Au-plate the entire surface. Scanning-electron microscopy revealed that the structure presented a high aspect ratio (thickness/resist width = 3.5), and metal structures could be fabricated without defects across the entire surface, including a high aspect ratio. The metallic structures had an average film thickness of 12.9 µm with σ = 0.49 µm, hardness of 600 HV, and slit width of 7.9 µm with σ = 0.25 µm. This microfabrication enables the fabrication of metal structures that deform dynamically in response to hydrodynamic forces in liquid and can be applied to fields such as environmental science, agriculture, and medicine.

A novel MEMS inertial switch with frictional electrode

This paper presents a frictional MEMS inertial switch with aiming to solve the problems of short contact time and bounce. According to contact principle in MEMS inertial switch, a new enhanced contact method by friction is proposed and a frictional switch is designed. To compare the frictional switch with common rigid switch and flexible switch, three switches were fabricated by micro electroforming technology and tested by a standard dropping hammer system. The tested results show that the contact time of rigid switch, flexible switch and frictional switch is 13 μs, 85 μs and 620 μs, respectively. Both rigid switch and flexible switch have bounce problem, while frictional switch is closed stably without bounce phenomenon. Frictional MEMS inertial switch has great advantages in enhancing contact.

Electroforming Technology as a Mold for Automobile Interiors

Electroforming Technology as a Mold for Automobile Interiors

Experimental Study on Three-Dimensional Microstructure Copper Electroforming Based on 3D Printing Technology.

In order to fabricate three-dimensional metal microstructures, a combined machining process based on 3D printing technology and electroforming technology is proposed. Firstly, a substrate with microstructures is fabricated by 3D printing technology, and then the microstructures were fabricated by electroforming technology. The influence of process parameters such as current density, distance between electrodes and pulse current duty cycle on the electroformed layer were studied and analyzed. It was determined that the peak current density 6A/dm2, the void ratio 20%, and the distance between electrodes 40 mm were the optimum process conditions of electroforming experiment. The electroforming experiments of different microstructures were carried out with the optimum process parameters.

Multi-material additive manufacturing of polymers and metals using fused filament fabrication and electroforming

This paper proposes an additive manufacturing method that combines fused filament fabrication (FFF) 3D printing and an electroforming technology to fabricate multi-material structures composed of resin and metal. In this method, an FFF 3D printer prints a resin mold that functions as a structural unit in a multi-material structure and as a sacrificial plastic mold for the addition of the metal material. This sacrificial mold is eventually removed. Electroforming the interior of a printed resin mold enables the fabrication of multi-material structures using resin and metal materials. The fabrication conditions for multi-material structures when using the proposed method were investigated and the surfaces of the resulting structures were evaluated. The fabrication conditions for the specified thickness per process and the total thicknesses from all the processes were determined. Furthermore, our results indicated that the shape of the side of the metal portion depended on the forming precision of the FFF 3D printer. We present an example of the fabrication of a gear shape from resin and metal.

Cost-effective near-perfect absorber at visible frequency based on homogenous meta-surface nickel with two-dimension cylinder array.

To date, near-perfect light absorbers at visible frequency are still severely impeded by the complicated architecture design and time-consuming costly fabrication procedures. In this work, we design and fabricate a new cost-effective near-perfect absorber at visible frequency based on homogenous meta-surface nickel (Ni) with a two-dimension cylinder array. The simulated and measured average absorption at normal incidence are beyond 94% and 92% over the entire visible wavelength band from 400 nm to 700 nm, respectively. Additionally, the absorbance property was well retained, and the absorptivity still remained beyond 70% when the incident angles vary from 0° to 60°. Our theoretically and experimentally results indicate that the broadband wide-angular absorption can be ascribed to the Rayleigh-Wood anomaly combined with slot modes induced by excited surface plasmon polaritons. Moreover, the low-cost double-beam interference lithography followed by soft nano-imprinting and electroforming technology, which are directly compatible with the cost-effective and high volume manufacturing requirements, are employed to fabricate the proposed absorber. The proposed approach is simple and inexpensive and the obtained ultrathin homogenous meta-surface nickel absorber can be rolled or folded on the surface of various optoelectronics, such as solar system and radiation thermal devices.

Experimental study on the replication quality of micro–nano cross-shaped structure arrays in injection molding

As the polymer products with micro-structured surface are widely in application, a better understanding of filling behaviors and quality improvement of micro---nano structures by injection molding is strongly demanded. In this paper, a nickel mold insert containing micro---nano cross-shaped structure array has been fabricated by electron beam lithography and electroforming technology subsequently. Filling behaviors of the polymer melt in the micro---nano cross-shaped structure cavities have been investigated under three molding conditions. These conditions are molding without packing, with insufficient and sufficient packing. Without packing, there existed a great difference of filling behaviors of polymer melt along the flow direction and vertical to the flow direction. Effects of the main processing parameters on the replication quality of molded columns have been discussed. The replication quality of micro---nano cross-shaped structure array is found to be improved with the increase of the mold temperature and the cooling time. Under sufficient packing, polymer melt would first flow into the left areas of micro---nano structures. Otherwise the center regions were first filled with insufficient packing. It is shown that the packing pressure and the packing time have the optimum values in the setting ranges.

Characteristic studies of a novel piezoelectric impedance micropump

This study reports the design, fabrication and test of an innovative valveless piezoelectric impedance micropump. The impedance micropump includes two nickel electroforming components, a stainless steel vibration plate, two glass tubes, a piezoelectric actuator and a glass substrate. A prototype of the micropump, with the dimensions of 16 mm × 9 mm × 1.0 mm, is made by precise manufacturing. The two plate nickel components were fabricated by multilevel electroforming technology on a stainless steel substrate. The top structure plate was electroformed by three-level structures, while the channel plate had a one-level structure. The vibration plate was manufactured by stainless steel through the lithography and etching process from MEMS fabrication technology. Holding a planar structure, the impedance micropump can be readily integrated with other microfluidic parts to form a lab-on-a-chip microdevice. The experimental results have demonstrated the liquid flow rate of 0.24 ml/min and the back pressure of 2.35 kPa, when the micropump was driven by the alternating sine-wave voltage of 200 Vpp at 18.4 kHz.

Effects of ultrasonic agitation on adhesion strength of micro electroforming Ni layer on Cu substrate

Micro electroforming is an important technology, which is widely used for fabricating micro metal devices in MEMS. The micro metal devices have the problem of poor adhesion strength, which has dramatically influenced the dimensional accuracy of the devices and seriously limited the development of the micro electroforming technology. In order to improve the adhesion strength, ultrasonic agitation method is applied during the micro electroforming process in this paper. To explore the effect of the ultrasonic agitation, micro electroforming experiments were carried out under ultrasonic and ultrasonic-free conditions. The effects of the ultrasonic agitation on the micro electroforming process were investigated by polarization and alternating current (a.c.) impedance methods. The real surface area of the electroforming layer was measured by cyclic voltammetry method. The compressive stress and the crystallite size of the electroforming layer were measured by X-ray Diffraction (XRD) method. The adhesion strength of the electroforming layer was measured by scratch test. The experimental results show that the imposition of the ultrasonic agitation decreases the polarization overpotential and increases the charge transfer process at the electrode–electrolyte interface during the electroforming process. The ultrasonic agitation increases the crystallite size and the real surface area, and reduces the compressive stress. Then the adhesion strength is improved about 47% by the ultrasonic agitation in average. In addition, mechanisms of the ultrasonic agitation improving the adhesion strength are originally explored in this paper. The mechanisms are that the ultrasonic agitation increases the crystallite size, which reduces the compressive stress. The lower the compressive stress is, the larger the adhesion strength is. Furthermore, the ultrasonic agitation increases the real surface area, enhances the mechanical interlocking strength and consequently increases the adhesion strength. This work contributes to fabricating the electroforming layer with large adhesion strength.

Design and Fabrication of an Array Microejector Driven by a Shear-Mode Piezoelectric Actuator

This paper reports a novel actuating design that uses� the shear deformation of a piezoelectric actuator to deflect a� bulge-diaphragm for driving an array microdroplet ejector. In essence,� we employed a circular-shaped actuator poled radial direction with� remnant polarization normal to the actuating electric field for inducing� the piezoelectric shear effect. The array microdroplet ejector consists� of a shear type piezoelectric actuator, a vibration plate, two chamber� plates, two channel plates and a nozzle plate. The vibration, chamber� and nozzle plate components are fabricated using nickel� electroforming technology, whereas the channel plate is fabricated by� etching of stainless steel. The diaphragm displacement was measured� by the laser two-dimensional scanning vibrometer. The ejected� droplets of the microejector were also observed via an optic� visualization system.

16.2: Invited Paper: Electroforming Technology for Manufacturing Thin Metal Masks with Very Small Apertures for OLED Display Manufacturing

The power of electroforming to faithfully capture and replicate metal features down to the atomic scale has been elegantly exploited to consistently produce OLED deposition masks with high yields. Using a unique combination of photolithography and electroforming, we have produced large area, (10‐15) µm thick nickel masks with apertures as small as 14 µm. This manufacturing technology is targeted to provide OLED masks for future generations of ultra‐high resolution display manufacturing, possibly down to 10 micron aperture sizes.

Study on Internal Stress in Micro-Electroformed Layer

Micro electroforming technology is widely used in fabrication of multilayer or moveable metal micro devices. The fabrication of these devices is usually suffered from high internal stress in micro-electroformed layers which seriously restricts the application and development of micro electroforming technology. Therefore, to control the internal stress is very important for improving the quality and performance of micro-electroformed layer. However, published studies on internal stress in the electroforming layer were mostly based on additive-free solution. According to additive solution, the effect of ultrasonic and current density on compressive stress occurring in the electroforming layer is investigated in this paper. The results indicate that the compressive stress keeps increasing with current density within range from 0.2 to 2 A/dm2. Meanwhile, the compressive stress in ultrasonic solution decreases by 73.4 MPa averagely comparing to that in ultrasonic-free solution, and the compressive stress also keeps decreasing with the ultrasonic power which gets the lowest value at 200W. Moreover, the mechanisms of additive-induced compressive stress and ultrasonic relieving compressive stress are discussed. This research work will complement the ultrasonic-stress reduction theory and may contribute to the development of micro electroforming technology.

Experimental Study on the Relationship between Dislocation Density and Internal Stress in Micro Electroforming Layer

In the micro electroforming process, the existence of electroforming layer defects caused by macro internal stress seriously limits the application and development of the micro electroforming technology. Currently, some studies have shown that ultrasonic can reduce the internal stress. But the formation process of the internal stress and the mechanism of ultrasonic stress relief in micro electroforming layer are still unclear now. In this paper, the relationship between dislocation density and internal stress under ultrasonic was studied. The results show that the ultrasonic can make the dislocation density increase and the compressive stress decrease. When the ultrasonic power is 200W, the dislocation density and the compressive stress culminate 3.8×10-15m-2 and-144.4MPa, respectively. The ultrasonic can excite the movement of dislocation proliferation, pile-up and opening, which leads to a micro plastic deformation in the crystal, and thereby releases the internal stress.

Mould insert fabrication of a single-mode fibre connector alignment structure optimized by justified partial metallization

For mass production of multiscale-optical components, microstructured moulding tools are needed. Metal tools are used for hot embossing or injection moulding of microcomponents made of a thermoplastic polymer. Microstructures with extremely tight specifications, e.g. low side wall roughness and high aspect ratios are generally made by lithographic procedures such as x-ray lithography or deep proton writing. However, these processes are unsuitable for low-cost mass production. An alternative manufacturing method of moulding tools has been developed at the Karlsruhe Institute of Technology (KIT). This article describes a mould insert fabrication and a new replication process for self-centring fibre alignment structures for low loss field installable single-mode fibre connectors, developed and fabricated by the Vrije Universiteit Brussel (VUB) in collaboration with TE Connectivity. These components are to be used in fibre-to-the-home networks and support the deployment and maintenance of fibre optic links. The special feature of this particular fibre connector is a self-centring fibre alignment, achieved by means of a through hole with deflectable cantilevers acting as micro-springs. The particular challenge is the electroforming of through holes with a centre hole diameter smaller than 125 µm. The fibre connector structure is prototyped by deep proton writing in polymethylmethacrylate and used as a sacrificial part. Using joining, physical vapour deposition and electroforming technology, a negative copy of the prototyped connector is transferred into nickel to be used as a moulding tool. The benefits of this replication technique are a rapid and economical fabrication of moulding tools with high-precision microstructures and a long tool life. With these moulding tools low-cost mass production is possible. We present the manufacturing chain we have established. Each individual manufacturing step of the mould insert fabrication will be shown in this report. The process reliability and suitability for mass production was tested by hot embossing.