Combination Of Screen Printing Research Articles

Combining Vapor Phase Polymerization and Screen Printing for Printed Electronics on Flexible Substrates

AbstractLarge area manufacturing of printed electronic components on ~A4‐sized substrates is demonstrated by the combination of screen printing and vapor phase polymerization (VPP) into poly(3,4‐ethylenedioxythiophene) (PEDOT). The oxidant layer required for the polymerization process is screen printed, and the resulting conductive polymer patterns are manufactured at high resolution (100 µm). Successful processing of several common oxidant species is demonstrated, and the thickness can be adjusted by altering the polymerization time. By comparing the polymer films of this work to a commercial PEDOT:PSS (PEDOT doped with poly(styrene sulfonate)) screen printing ink shows improved surface roughness (26 vs 69 nm), higher conductivity (500 vs 100 S cm–1) and better resolution (100 vs 200 µm). Organic electrochemical transistors, in which the transistor channel is polymerized into PEDOT through VPP, are also demonstrated to further emphasize on the applicability of this manufacturing approach. The resulting transistor devices are not only functional, they also show remarkable switching behavior with respect to ON current levels (–70 mA at –1 V), ON/OFF ratios (>105), switching times (tens of ms) and transconductance values (>100 mS) in standalone transistor devices, in addition to a high amplification factor (>30) upon integration into a screen printed inverter circuit.

Voltammetry in Two‐Electrode Mode for Rapid Electrochemical Screening Using a Fully Printed and Flexible Multiplexer Sensor

AbstractA multiplexed electrochemical platform has been designed for electrochemical screening applications, such as bacteria detection. It includes 16×16 electrochemical cell array in a two‐electrode mode fabricated by a combination of screen printing, inkjet printing, and flash‐light sintering techniques wherein each cell is addressed sequentially by a portable multiplexer potentiostat. This multiplexer unit is capable of making a total of 256 independent voltametric measurements that were validated by performing cyclic voltammetry in two‐electrode mode using four different redox mediators: [Fe(CN)6]3−/4−, FcMeOH, Ru[(NH3)6]Cl3 and K2[IrCl6]. The smart design and the use of mass production techniques makes the multiplexer device applicable for numerous electrochemical applications including health, food, and environmental monitoring.

Simultaneous formation of fine and large-area electrode patterns using screen-offset printing and its application to the patterning on adhesive materials

Additive-type printing techniques such as gravure-offset printing and screen printing are effective for low-cost and ecofriendly electrode pattern formation. Gravure-offset printing is effective for fine pattern formation with widths on the order of 10–20 µm, whereas screen printing is effective for the formation of large-area patterns. However, it is difficult to simultaneously form fine and large-area patterns using these printing techniques. In this study, we demonstrate that fine (minimum width of 15 µm) and medium- as well as large-area patterns can be formed simultaneously using our developed screen-offset printing technique, which is a combination of screen printing on a silicone blanket and transfer printing from the blanket to a substrate. Furthermore, we demonstrate the application of our method to printing on adhesive materials, which allows electrode formation without applying heat to the film substrate.

Fabrication of electrodes and near-field communication tags based on screen printing of silver seed patterns and copper electroless plating

Highly conductive patterns were studied based on a combination of screen printing and electroless plating using Ag and Cu, respectively. Furthermore, near-field communication (NFC) tags were fabricated to demonstrate the performance of the conductive patterns. Ag and Cu patterns with thicknesses of 2-6 µm and 6 µm, respectively, were obtained. The conductivity of the pattern after the electroplating process was improved to approximately 20-30 times higher than that of the Ag-printed seed pattern, and its performance was 30% of that of a traditional chemical-etched pattern based on the photolithography process. Moreover, the Cu electroless plated pattern reached a level of 50% of the bulk Ag material. In addition, the resonance frequency of the fabricated NFC tag was measured using various numbers of coil turns, and was observed to range from 16 to 25 MHz. All the experimental processes were performed on a mass production platform and approached the commercialization level.

Solid oxide fuel cell with Ni–Al support

Metal-supported solid oxide fuel cells are considered as next generation of fuel cells. In this configuration, the use of metal support allows lowering the cost of fuel cell fabrication and provides enhanced durability. The paper presents the results concerning the manufacture and research of metal-supported solid oxide fuel cells with YSZ (yttria-stabilized zirconia) electrolyte. As a metal support the porous Ni–Al plates manufactured by combustion synthesis were used. The effects of synthesis conditions and composition of the Ni–Al samples on their properties were investigated. Solid oxide fuel cells with the structure of Ni–YSZ anode/YSZ electrolyte/LSCF cathode were fabricated by the combination of screen printing, magnetron sputtering, and electron beam treatment. The cell performance was analyzed by current–voltage measurements during operation at 700, 750, 800 and 850 °C. The obtained results are very promising at such an early stage of research for the future development of this technology.

Fabrication and performances of all solid-state symmetric sodium battery based on NASICON-related compounds

The electrochemical performance of a novel all solid-state sodium-ion symmetrical battery with Na3Zr2Si2PO12 (NASICON) as a solid electrolyte and Na3V2(PO4)3 (NVP) as the active electrode material was examined. The all solid-state cell was fabricated by a combination of screen printing and hot pressing. The electrochemical characterization of the NVP active material in the metallic sodium half-cells at 80°C indicated that this NASICON-related phosphate undergoes reversible sodium extraction/insertion reactions at electrode potentials of 1.6 and 3.4V vs. Na. These insertion properties allowed the NVP to function successfully as the active material for both the positive and negative electrodes in a sodium-ion cell configuration. A charge–discharge cycling test of the fabricated symmetrical all solid-state cell was carried out at room temperature within the voltage range of 0.01 and 1.9V. It was found that the cell can work as a secondary battery and showed first discharge capacities of 68 and 32mAhg−1 at the current densities of 1.2 and 10μAcm−2, respectively. Furthermore, the lack of reactivity between the all-solid-state cell components during long-term cycling was confirmed.

Stability and Efficiency of Screen-Printed Wearable and Washable Antennas

Wearable antennas, integrated into garments, are prone to get dirty. Therefore, for the first time in literature, washable antennas are proposed by covering textile antennas by a breathable thermoplastic polyurethane coating, protecting the antennas against water absorption and corrosion. The washability of coated wearable antennas produced by screen printing conductive ink onto a textile substrate is compared to coated wearable antennas based on an electrotextile, analyzing performance in terms of their reflection coefficient and radiation efficiency before and after washing. The combination of screen printing and coating provides stable antenna performance with sufficiently high radiation efficiency after several washing cycles.

Dielectric, Ferroelectric, Pyroelectric, and Piezoelectric Properties of La‐Modified Lead‐Free Sodium–Potassium Bismuth Titanate Thick Films

La2O3‐doped sodium–potassium bismuth titanate (Na0.82K0.18)0.5Bi0.5TiO3(NKBT) lead‐free thick films have been prepared on Pt‐electroded alumina substrates using a combination of screen printing and subsequent infiltration of the corresponding composite sol. Their densification, microstructure, dielectric, ferroelectric, pyroelectric, and piezoelectric properties were investigated with variation of the La2O3content. The resulting 40 μm‐thick NKBT films doped with 1.0 mol% La2O3show minimum leakage current density of 1.56 × 10−9A/cm2at an applied field of 100 kV/cm, remanent polarization of 21.6 μC/cm2, and coercive field of 58 kV/cm. The high pyroelectric coefficient of 2.0 × 10−4C·(m2·°C)−1, the calculated detectivity figure of merit as high as 0.81 × 10−5Pa−0.5, and the value of remanentd33effof 108 pm/V at room temperature (20°C) were observed in 1.0 mol% La2O3‐doped NKBT thick films, which can be comparable with that of the commonly used lead‐based materials. The enhancement of the pyroelectric and piezoelectric performances is attributed to the reduction of lattice tetragonality, uniform microstructure, and improved densification in La‐modified NKBT thick films.

Effect of repeated composite sol infiltrations on the dielectric and piezoelectric properties of a Bi 0.5(Na 0.82K 0.18) 0.5TiO 3 lead free thick film

Bi 0.5(Na 0.82K 0.18) 0.5TiO 3 lead free thick films have been produced using a combination of screen printing and subsequent infiltration of corresponding composite sol. Their structure, dielectric, ferroelectric and piezoelectric properties were investigated with variation in the number of composite sol infiltrations and the nanopowder loading in composite sol. Dielectric constant, remanent polarization, and piezoelectric coefficient have been shown to increase with increasing numbers of composite sol infiltration. Dielectric and ferroelectric properties of the thick films are found to be strongly dependent on the powder concentration of composite sols. The resulting 40 μm thick films infiltrated with 1.5 g/ml composite sols have maximum relative permittivity of 569 (at 10 kHz), remanent polarization of 21.3 μC/cm 2, coercive field of 80 kV/cm, and longitudinal effective piezoelectric coefficient d 33eff of 109 pm/V. The performance of these lead free piezoelectric thick films is comparable to the corresponding bulk ceramics.

Disposable Gold Electrode Array for Simultaneous Electrochemical Studies

AbstractAn efficient and inexpensive eight gold electrode array has been manufactured by a combination of screen printing and gold electrodeposition techniques. Gold electrodeposition was performed in potentiostatic and galvanostatic conditions. Different treatments, involving temperature and polishing control, led to electrodes with different roughness. The electrochemical behavior of the generated gold surface was studied by cyclic voltammetry showing the characteristic response of polycrystalline gold, in contrast with disposable gold electrodes fabricated by screen printing from gold inks. The electrodes were chemically modified through the adsorption of alkanethiols self‐assembled monolayers and the coupling of a model protein. Both reactions were followed by cyclic voltammetry and Electrochemical Impedance Spectroscopy (EIS). The electrodes have shown high reproducibility in their electrochemical behavior as well as in their modifications.

Rheology and Firing Properties of Phosphor Pastes for CRT Displays

A new method of manufacturing phosphor screens for flat CRT displays is developed by a combination of screen printing and thermal transfer processes. The main issues for high resolution displays are the printability and firing properties of phosphor pastes, and packing density of particles deposited on panels. The most important components which are closely connected with these requirements are the polymeric binders. The polymeric binders which lead to weak flocculation of phosphor particles provide the good rheological properties for reproduction of precise micropatterns. Because of weak adsorption affinity for the particle surfaces, the pastes prepared with such binders are thoroughly fired without ashes on heating at the temperature where the complete decomposition of binder polymers takes place. The glass panels are incorporated with electron gun and the CRT panels are built as model displays. The brightness of newly developed displays will be acceptable for practice applications.

Low-power thick-film gas sensor obtained by a combination of screen printing and micromachining techniques

A novel prototype of low-power thick-film gas sensor deposited by screen-printing onto a micromachined hotplate is presented. The micro-heater is designed to maintain a film temperature of 400°C with less than 30 mW of input power. The fabrication process involves a combination of standard, VLSI-compatible, micromachining procedures and computer-aided screen-printing. A dielectric membrane of Si 3N 4 and SiO 2 has been obtained with an embedded poly-Si resistor acting as a heating element. The bonding pad and contacts have been realised by a Ti/TiN/Cr/Au structure and the sensing film has been deposited by a screen-printing technique. Here follows a characterisation of a device, based on SnO 2 sensing film, at working conditions together with the response curve for CH 4 and NO 2. We will also address some important improvements to the micro-hotplate structure, which leads to an increased flexibility of the device.

Evaluation of Microelectrode Arrays for Amperometric Detection by Scanning Electrochemical Microscopy

Ultramicroelectrode arrays have been manufactured by a combination of screen printing and laser ablation with different sizes of the active electrode areas and different interelectrode spacings. The participation of each array element in the heterogeneous redox reaction can be checked with the help of scanning electrochemical microscopy (SECM). Because the active electrode area is recessed compared to the insulating cover layer of the sensor, a loss in sensitivity is found on such arrays compared to an electrode array of the same geometry which is in plane with its insulating surrounding. Consequences for the application of such electrode arrays as the basis of sensors in hand-held devices for in-field testing are discussed.

Interconnection Technology for Advanced High Density Thick Films

Thick film screen printing technology is able to reach a pitch of 250 μm. In an attempt to achieve lower values, two approaches have been developed so far. Both are based on the combination of screen printing as a deposition technique and photolithography for the patterning. The first approach uses photoimageable conductor and dielectric pastes; the second is based on photoimageable dielectric and etching of the fired conductor. In order to obtain a full characterisation of both processes, a test module was designed and manufactured by using the first process and identical test modules were provided by the supplier using the second technology. The design of the test module is based on a two‐layer interconnection pattern including structures for testing cross‐overs, via interconnections with various resolutions (down to 50 μm via size), in order to investigate the limits of these technologies. This paper gives a comparison of these two approaches based on the results of electrical and mechanical measurements performed on both sets of the test modules. Electrical parameters and resolution data are discussed for both processes. The chip and wire assembly method is evaluated to prequalify the technology as an advanced MCM‐C technology for telecoms applications. Finally, the results of reliability tests (humidity ageing and burn‐in) are presented.