Fabrication Of Various Electronic Devices Research Articles

Extrusion-based additive manufacturing of aluminium-filled ethylene vinyl acetate for electrically conductive 3D part printing

Addition of carbon-based fillers to enhance electrical conductivity is quite popular but addition of metal fillers is still a challenge due to oxidation and unavailability of metal nano-powders. In this paper, fabrication of flexible electrically conductive parts is proposed using aluminium metal powder as filler material. Aluminium metal powder is mixed with ethylene vinyl acetate (EVA) by chemical mixing process. Cyclohexane is used as a mixing medium in which EVA is dissolved and aluminium powder is added by weight. An in-house developed material extrusion tool mounted on CNC milling machine is used for printing of flexible electrically conductive samples. Pellet-based extrusion process is used for printing flexible parts as conventional filament-based 3D is not suitable due to buckling. Composite with filler loading in 5%, 10%, 20% and 30% were made and samples were printed. Investigations were made on printability of composite and its electrical conductivity. The aluminium fillers presence and dispersion in polymer were ensured. The samples were printed in temperature range of 130–140 °C through 0.4 mm diameter nozzle. It was found that the resistivity drops by around 60% on varying the filler concentration from 20% to 30%; 81.6 kΩ is the lowest resistance observed with 30% filler concentration. A simulation study on thermal behaviour of material extrusion tool has been done and is validated practically. The application of flexible electrically conductive parts lies in fabrication of various electronic devices like antenna, display boards, solar panels, and wearable health monitoring devices.

Radiation‐Tolerant Electronic Devices Using Wide Bandgap Semiconductors

AbstractThe aspiration of electronic technologies that are resistant to high‐energy cosmic radiation is essential for current harsh radiation environment exploration. Integrated circuits mostly require post‐processing after designing, making their structures more complex than the standard systems. Thus, unique designs and strategies are developed to enable the high tolerance of space electronics to radiation in nuclear and avionic applications. The wide bandgap semiconductor (WBG) materials with excellent electronic/optical properties and structural stability are appealing options for radiation‐immune applications. Here, in this article, the development and fabrication of various electronic devices have been reviewed using different wide bandgap materials for radiation‐hardened applications. Detailed investigations are discussed, from the fundamental wide bandgap materials withstanding limited irradiation to the development processes of the electronic devices used in harsh environments. Furthermore, the challenges and future perspectives of the WBG‐based radiation harsh electronic devices are also highlighted in this review with commercial application in space stations and aircraft.

Submicron Cu@glass core-shell powders for the preparation of conductive thick films on ceramic substrates

Coating Cu powders with glasses to form a core-shell structure provides an important route to achieve uniform distribution of glass components in Cu pastes for the fabrication of various electronic devices. In this study, submicron Cu powders are synthesized via a chemical solution method at first, and then coated with Bi-Si-B-Zn-Al glass by a sol-gel method to form submicron Cu@glass core-shell powders which are then prepared into Cu pastes with different glass contents. The Cu@glass pastes are printed on alumina ceramic substrates and sintered at temperatures ranging from 600 to 800 °C to form conductive thick films. Enhanced anti-oxidation properties are observed for the Cu@glass core-shell powders. The Cu pastes can be sintered into conductive films with a good electric conductivity and adhesion strength on alumina substrate at a relatively low temperature of 600 °C. A low resistivity of 3.0 µΩ cm is achieved for the sintered Cu film with a glass content of 6 wt%. The glass shells are observed to transform into uniformly distributed glass phases which provide advantages for the formation of Cu-grain conductive pathway at a low sintering temperature.

Formation of Surface-Wrinkled Metal Nanosheets via Thermally Assisted Nanotransfer Printing

Nanopatterning methods for pattern formation of high-resolution nanostructures are essential for the fabrication of various electronic devices, including wearable displays, high-performance semiconductor devices, and smart biosensor systems. Among advanced nanopatterning methods, nanotransfer printing (nTP) has attracted considerable attention due to its process simplicity, low cost, and great pattern resolution. However, to diversify the pattern geometries for wide device applications, more effective and useful nTP based patterning methods must be developed. Here, we introduce a facile and practical nanofabrication method to obtain various three-dimensional (3D) ultra-thin metallic films via thermally assisted nTP (T-nTP). We show how to generate surface-wrinkled 3D nanostructures, such as angular line, concave-valley, and convex-hill structures. We also demonstrate the principle for effectively forming 3D nanosheets by T-nTP, using Si master molds with a low aspect ratio (A/R ≤ 1). In addition, we explain how to obtain a 3D wavy structure when using a mold with high A/R (≥ 3), based on the isotropic deposition process. We also produced a highly ordered 3D Au nanosheet on flexible PET over a large area (> 15 µm). We expect that this T-nTP approach using various Si mold shapes will be applied for the useful fabrication of various metal/oxide nanostructured devices with high surface area.

Synthesis and characterization of copper ink and direct printing of copper patterns by inkjet printing for electronic devices

Among the conventional metallic inks used in the printing process, silver exhibits high conductivity and thermal stability. Nevertheless, due to the high cost of silver, it cannot be extensively used for the fabrication of inks. As a competitive alternative, copper can be considered as a substitute for silver; however, copper ink oxidizes under certain atmospheric conditions. To meet these shortcomings, a cost effective, highly conductive, and oxidation-free copper-based ink has been synthesized in this study, wherein, oxidation of the copper particles in the copper-based ink was prevented by using copper complexes. The copper ink thus fabricated was printed on chemically treated Si/SiO2 substrates followed by the characterization of the printed copper films. The results of this study confirmed that the synthesized copper ink exhibited properties suitable for its use in the inkjet printing process for fabrication of various electronic devices.

Co-Ni Electroless Composite Plating of Nanometer-Leveled Diamond Particles on Micrometer-Leveled Plastic Balls and the Application of Thus Prepared Devices to Various Electronics Processes

The aim of this paper is to develop a, lightweight and forceful Magnetic abrasive particles (MAP). Magnetic field assisted finishing was performed to examine the fabricated MAPs. A new MAPs based on the nickel-cobalt diamond composite plated plastic ball have been prepared successfully. The finishing results for “Damascene” sample or “Copper Overhang Generated in the Direct Laser Via Process” have suggested the powerful ability of the new MAPs to the field of the fabrication of various electronic devices. In this paper a, lightweight and forceful MAP has been developed. And Magnetic field assisted finishing was performed to examine the fabricated MAPs. A new bound MAP based on the electroless cobalt-nickel boron, 20 nm sized diamond composite plating to plastic balls was prepared. 10 mirometer sized Plastic ball was used as support here for MAPs growth due to its lightweight properties.

Co-Ni Electroless Composite Plating of Nanometer-Leveled Diamond Particles on Micrometer-Leveled Plastic Balls and the Application of Thus Prepared Devices to Various Electronics Processes

The aim of this paper is to develop a, lightweight and forceful Magnetic abrasive particles (MAP). Magnetic field assisted finishing was performed to examine the fabricated MAPs. A new MAPs based on the nickel-cobalt diamond composite plated plastic ball have been prepared successfully. The finishing results for “Damascene” sample or “Copper Overhang Generated in the Direct Laser Via Process” have suggested the powerful ability of the new MAPs to the field of the fabrication of various electronic devices. Magnetic abrasive particles (MAPs) are crucial to ensure finishing quality and accuracy in magnetic abrasive finishing (MAF) processing. Conventional MAPs consist of ferrous particles and abrasive, such as Al2O3, SiC, ZrO2, B4C as well as diamond, cubic boron nitride, MgO, CeO2 or fumed silica. The MAPs can be used as unbound, loosely bound or bound. One of them KMX 80 (trade name) are frequently used as commercial magnetic abrasives.　This abrasive particle consists of dispersed aluminum oxide grains in iron matrix particles with the average diameter of 80 micrometer. Here, ferrous particles, which are mostly conventional used magnetic particle in MAF process, provide force of grinding via magnetic field. But due to the corrosion and softness of ferrous materials, the post-cleaning of the surface finished by the MAPs containing ferrous particles becomes the most time-consuming and critical procedure in some ultra-precision MAF processing, other magnetic particles should be urgent to be developed to replace the conventional ferrous particles. In this paper a, lightweight and forceful MAP has been developed. And Magnetic field assisted finishing was performed to examine the fabricated MAPs. A new bound MAP based on the electroless cobalt-nickel boron, 20 nm sized diamond composite plating to plastic balls was prepared. 10 mirometer sized Plastic ball was used as support here for MAPs growth due to its lightweight properties. “Damascene” sample were supplied by Selete Co. Ltd. The original surface of the sample was covered with over-coated copper layer. Thus supplied sample was used as a workpiece. The AFM images of the surface profiles was captured after finishing by KMX80 (3 mins) followed by the cobalt-nickel diamond composite plated plastic balls for 8 mins. The AFM images for the sample after MAF suggests that nano meter-sized surface smoothing could be attained. The best finishing conditions will be needed to be investigated in future. Another approach of MAP to electronic devices has been tried for removal of copper overhang generated in the direct Laser via process by use of magnetic polishing method. In recent years, via holes has been used for the connection of external wiring and internal wiring of the multilayer substrate. When copper foil of wiring layer was processed by laser, melted copper was adhered, so projections called “overhang” are formed around the opening of via hole. Adhesiveness and flatness of plating will be decreased by the overhang, therefore removal process of them will be indispensable. Therefore magnetic polishing method has been tried as a novel removal technique in this study. In conclusion, the finishing results for “Overhang” sample have suggest the powerful ability of the new MAPs to the field of the fabrication of the FWB(Printed Wiring Board) devices.

The evolution of graphene-based electronic devices

Successful isolation of single-layer graphene, the two-dimensional allotrope of carbon from graphite, has fuelled a lot of interest in exploring the feasibility of using it for fabrication of various electronic devices, particularly because of its exceptional electronic properties. Graphene is poised to save Moore's law by acting as a successor of silicon-based electronics. This article reviews the success story of this allotrope with a focus on the structure, properties and preparation of graphene as well as its various device applications.

A Review of SiC Reactive Ion Etching in Fluorinated Plasmas

Research and development in semiconducting silicon carbide (SiC) technology has produced significant progress in the past five years in many areas: material (bulk and thin film) growth, device fabrication, and applications. A major factor in this rapid growth has been the development of SiC bulk crystals and the availability of crystalline substrates. Current leading applications for SiC devices include high power and high temperature devices and light emitting diodes. Due to the strong bonding between Si and C (Si–C = 1.34×Si–Si), wet chemical etching can only be performed at high temperature. Therefore, plasma-based (“dry”) etching plays the crucial role of patterning SiC for the fabrication of various electronic devices. In the past several years, reactive ion etching (RIE) of SiC polytypes (3C and 6H) has been investigated in fluorinated gases (primarily CHF3, CBrF3, CF4, SF6, and NF3), usually mixed with oxygen and occasionally with other additives or in a mixture of fluorinated gases. In this paper, a review of SiC RIE is presented. The primary emphasis is on etching of the 3C and 6H polytypes, but some results on RIE of the 4H polytype are included. The paper covers the basic etching mechanisms, provides typical etching properties in selected plasma conditions, discusses the effects of changes in various etching parameters, such as plasma pressure, density and power, etching time, etc. The etching of features of sizes varying from sub-μm to tens of μm's is addressed. Finally, optimum etching conditions and trade-offs are considered for various device configurations.