Conventional Screen Printing Research Articles

Enhanced performance of an anode-supported YSZ thin electrolyte fuel cell with a laser-deposited Sm0.2Ce0.8O1.9 interlayer

Abstract A power density of over 1.4 W cm−2 at 0.7 V was achieved at 750 °C for an anode-supported YSZ thin electrolyte fuel cell with a dense Sm0.2Ce0.8O1.9 (SDC) interlayer fabricated by pulsed laser deposition, while the cell with a conventional porous SDC interlayer exhibited only 0.8 W cm−2 at this voltage. The dense SDC interlayer significantly reduced the ohmic resistance of the fuel cell. For example, at 750 °C, the ohmic resistance of the fuel cell with a dense SDC interlayer was 0.08 Ω cm2; while that of the cell with a porous SDC interlayer fabricated by conventional screen-printing was 0.16 Ω cm2. The pronounced reduction in ohmic resistance might be due to the fully dense structure and thus improved electrical conductivity of the SDC interlayer, increased contact area at the interface between the dense SDC interlayer and the YSZ electrolyte, and suppressed Zr migration into the SDC interlayer.

An additive method to fabricate conductive lines and electronic components directly by laser microcladding electronic materials

In this article, a laser direct-write method to fabricate conductive lines and electronic components on insulating boards by using laser microcladding electronic materials is reported. A workstation for implementing this direct-write method was developed, which integrated material deposition (micropen) and laser processing on a single machine. With the computer-aided design/computer-aided manufacturing (CAD/CAM) capability of the workstation, conductive lines, resistors, capacitors, inductors, and thick-film sensors with different patterns were fabricated successfully by this technique in air without mask and with high deposition rates. The minimum widths of the conductive lines and other functional materials were much less than those obtained by the conventional screen printing method. The experimental results demonstrated that passive components and thick-film sensors made by this method have the same properties as those made by conventional thick-film methods, whereas thick films fabricated by this method have much lower widths than those fabricated by the conventional thick-film method. This technique provides a novel method to fabricate the conductive lines and electronic components with high precision and high speed.

Enhanced ASC Performance at 600{degree sign}C by Ceria Barrier Layer Optimisation

Reduction of the SOFC operating temperature to 600{degree sign}C is an effective approach for reducing the costs of applied materials and increasing the lifetime of SOFC systems. The anode-supported cell design (ASC) with thin electrolyte is a promising configuration for operation at this temperature. This paper deals with the ASC performance improvement at 600oC by optimisation of the ceria barrier layer that is placed between the La0.6Sr0.4CoO3-δ cathode and the zirconia electrolyte to prevent the formation of resistive secondary phases. Conventional screen printing has been used for the deposition of the ceria barrier layer. The improved screen printed ceria layer results in an increase in maximum power output of the anode supprted cell from 260 to 580 mW/cm2 at an operating temperature of 600oC. The performance improvement was mainly caused by a significant reduction of ohmic losses.

Printing technologies for the gate and source/drain electrodes of OTFTs

This is a report on the fabrication of a flexible OTFT backplane for electrophoretic display (EPD) using a printing technology. A practical printing technology for a polycarbonate substrate was developed by combining the conventional screen and inkjet printing technologies with the wet etching and oxygen plasma processes. For the gate electrode, the screen printing technology with Ag ink was developed to define the minimum line width of ∼5 μm and the thickness of ∼70 nm with the resistivity of ∼10‐6 ?•cm, which are suitable for displays with SVGA resolution. For the source and drain (S/D) electrodes, PEDOT:PSS, whose conductivity was drastically enhanced to 450 S/cm by adding 10 wt% glycerol, was adopted. In addition, the modified PEDOT:PSS could be neatly confined in the specific S/D electrode area that had been pretreated with oxygen. The OTFTs that made use of the developed printing technology produced a mobility of 0.13 cm2/Vs.ec and an on/off current ratio of 106, which are comparable to those using thermally evaporated Au for the S/D electrode.

Advanced screen printing technique for high definition front side metallization of crystalline silicon solar cells

This work presents a new, readily implementable screen printing technique for the front side metallization of textured mono- and multi-crystalline silicon solar cells. The use of a heated print chuck to increase the substrate temperature during the screen print process enables a significantly reduced printed line width for conventional and fine line screen printing. The influence of substrate temperature on the line definition is optically and electrically analysed. Within this work an efficiency gain of 1% relative as well as continuous printed lines showing a width below 60 μm have been achieved on textured silicon surfaces at high throughput rates.

Electron microscopy analysis of crystalline silicon islands formed on screen-printed aluminum-doped p-type silicon surfaces

The origin of a not yet understood concentration peak, which is generally measured at the surface of aluminum-doped p+ regions produced in a conventional screen-printing process is investigated. Our findings provide clear experimental evidence that the concentration peak is due to the microscopic structures formed at the silicon surface during the firing process. To characterize the microscopic nature of the islands (lateral dimensions of 1–3 μm) and line networks of self-assembled nanostructures (lateral dimension of ≤50 nm), transmission electron microscopy, scanning electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray analysis are combined. Aluminum inclusions are detected 50 nm below the surface of the islands and crystalline aluminum precipitates of ≤7 nm in diameter are found within the bulk of the islands. In addition, aluminum inclusions (lateral dimension of ∼30 nm) are found within the bulk of the self-assembled line networks.

Direct electron transfer of Horseradish peroxidase on porous structure of screen-printed electrode

Disposable hydrogen peroxide biosensor was developed based on the direct electron transfer of horseradish peroxidase (HRP) on porous screen-printed carbon electrodes. Conventional screen-printing process was manually performed to fabricate the planar carbon electrodes, which were endowed with porous surfaces especially after anodizing pretreatment. The cyclic voltammetry experiment indicated a pair of stable and well-defined redox peaks with a formal potential of −0.33 V. And the formal potential was pH-dependent, having a slope of −55.2 mV/pH which indicated one electron transfer. The heterogeneous electron transfer rate constant k s was estimated to be 13.28 ± 4.80 s −1. Additionally, the sensitivity was 143.3 mA M −1 cm −2 and the linear range was from 5.98 to 35.36 μM. In conclusion, the present work achieved the direct electron transfer of HRP on screen-printed electrodes without any promoters. The porous structure of screen-printed carbon electrodes facilitated the direct electron transfer between the active sites of HRP and the electrodes due to large amounts of conductive sites available on the surface for contacting with enzyme molecules. Moreover, the proposed biosensor could be mass-produced at low price, promising for commercial application.

Adaptive screen printing for rapid manufacturing

PurposeTo develop a rapid manufacturing process for high‐volume free from fabrication of parts that is based on the high speed printing method which is screen printing. This technique will also be applied for printing in general.Design/methodology/approachThis method involves continuous change in a layer's pattern (negative image of the layer) according to a very thin slice of the object to be printed. Three adaptive screen printing methods are proposed as an alternative to two dimensional screen printing. A comparative analysis is conducted and the possibility of combining the method is proposed.FindingsEach of the three methods studied required further work as they all had major constraints. However, their combination may be the solution to the development of a rapid manufacturing process.Originality/valueThe originality is in the adaptive screen principle the screen being used will be capable to auto‐change the pattern of the layer to be printed instead of introducing a new stencil for every layer as in conventional screen printing.

Preparation of piezoelectric 0.1Pb(Zn 0.5W 0.5)O 3–0.9Pb(Zr 0.5Ti 0.5)O 3 solid solution and thick films for low temperature firing on a Si-substrate

A newly designed lead zirconate titanate (PZT) solid solution 0.1Pb(Zn 0.5W 0.5)O 3–0.9Pb(Zr 0.5Ti 0.5)O 3 was prepared. It is feasible for a low temperature firing. X-ray diffraction shows that its structure is a single perovskite phase, and its thick films were successfully fabricated on a Pt/TiO 2/SiN x /Si-substrate through the screen printing method. A conventional screen printing thick film and a hybrid thick film (screen printing and PZT sol infiltration) was also compared. According to an SEM study, the prepared thick film showed a much denser microstructure with the sol infiltration method. The electrical properties of the prepared PZT solid solution and its thick film were predominantly realized in a low temperature region. The dielectric constant of a conventional screen printing thick film and the hybrid thick film (sintered at 900 °C), was 703.5 and 911.3, respectively.

Surface Coating of Reactive Layer with Inner Nano-Pores on Lantanium Gallium Based Oxide

A layer consisting of La0.6Sr0.4CoO3-d particles with inner nano-pores is coated on the La0.7Sr0.3Ga0.6Fe0.4O3-d oxide to improve the surface reaction resulting in high oxygen permeability. The La0.6Sr0.4CoO3-d particles with inner nano-pores are synthesized by an ultrasonic spray pyrolysis method. The permeated oxygen contents from air to helium gas were measured using gas chromatography after the synthesized particles were coated on the La0.7Sr0.3Ga0.6Fe0.4O3-d oxide by the conventional screen-printing. The results demonstrated that the reactive free surfaces of the nano-pores are an important factor in determining the oxygen permeation for application such as gas separation membrane and ceramic fuel cell.

Transient response of resistive-type NO 2 sensor on temperature change

The transient resistance response of a SnO 2 sensor after an abrupt temperature change was measured, and consequently peculiar responses of the sensor in NO 2 gas were observed. SnO 2 thick film sensors, with a thickness of approximately 10 μm, were prepared by a conventional screen printing method. The films were printed on interdigitated Pt electrodes deposited on the front side of an Al 2O 3 substrate and a Pt heater was deposited on the backside of the substrate. Gas-sensing measurements were carried out using 20% O 2/N 2 with a few ppm NO 2 gas flow. The temperature of the sensor was changed in steps of 100 °C from 100 to 400 °C, and kept constant for 2 min at each step using an electronic control circuit. A reference sensor fabricated in ZnSb 2O 6 was also prepared and measured by the same method. In addition, the adsorption and desorption characteristics of the gas-sensing material for NO 2 were examined by doing temperature programmed desorption (TPD) measurements. The resistance decreased as the temperature increased, and increased when NO 2 was present. The transient response in NO 2 had a peaked point between 200 and 300 °C. On the other hand, no peak response was observed for the ZnSb 2O 6 sensor. As seen from the TPD measurements, the desorbed NO 2 from SnO 2 was much higher than that from ZnSb 2O 6, therefore, the peak response of the SnO 2 sensor seems to be related to the adsorption and desorption properties of the gas-sensing material.

Diffusion Bonding Assisted by Centrifugal Force

A new joining process assisted by centrifugal acceleration is proposed. The process requires no pressurizing media, and enables diffusion bonding of parts with complex shapes, as demonstrated in this paper. As an additional merit, contamination from media can be basically avoided. These features derive from an unique pressing method that uses high centrifugal force of up to -90km/s2, enhancing the joining strength of interfaces. Trial results indicate a tensile strength for Al2O3/Al/stainless steel joints equivalent to that of conventional diffusion bonded joints and double the adhesion strength of Cu thick film on quartz glass as compared to conventional screen printing.

Spots before the eyes: Can ink jet printers match expectations?†

The mechanism by which the coloured image is formed by digital ink jet printing is very different from that of conventional screen printing methods and success depends on the use of sophisticated software and hardware. Some commercially available systems are listed in this paper and the basic principles of the standardisation of scanners, monitors and jet printers given. Ink jet printing machines at present available for textiles are reviewed and their limitations with regard to dye selection, shade gamuts and reproducibilty are quantified. Repeatability and shade reproducibility tests of digitally printed textiles are reported showing that improvements are required in the transformation of pattern data to the printed output.

Patterning technology of carbon nanotubes for field emission displays

Patterning technology of fine carbon nanotube (CNT) pixels on a hard metal has been developed by using photolithography process for field emission displays (FEDs). The photolithography method produced much sharper and smaller CNT pixels compared with those made by the conventional screen-printing process. The CNTs in the patterned pixels by photolithography were uniformly distributed in a 2 in. diagonal area. The density of CNT bundles in the patterned pixels was about 10/μm2. After patterning and heat treatment process below 300 °C, most of CNT bundles on the cathode were aligned perpendicular to the substrate. The turn-on field of patterned CNTs was less than 4.2 V/μm and the current density was about 2.1 mA/cm2 at 6 V/μm. This process might be applicable to field emitter arrays for high resolution FEDs.

Image Permanence: Commercial Signage/Fleet Graphics

The permanence or durability of outdoor signage and fleet graphics depends on three main factors. These factors are the construction, the application, and the environment in which the graphic is exposed. Fade resistance is but one property that determines the permanence. More printing of outdoor signage is being done more by digital printing and less by screen printing. The fade resistance of graphics printed by piezo ink jet inks is approaching that of graphics printed by conventional screen printing methods. Retained solvents, though, are limiting the permanence of some demanding graphics printed by solvent-based piezo ink jet inks.

Ink‐jet printing of textiles under the microscope

Jet printing of textiles with equipment based on the charged drop, piezo and bubblejet technologies, which were originally developed for paper reprographics, is now fairly common, particularly for making sample prints in a rapid response environment. However, compared with conventional screen printing, these systems impose some limitations in the number and gamut of shades that can be produced and in fabric preparation, productivity and cost. The underlying principles of the formation of the coloured pixels which make up the printed design using a jet printer have been studied both at the microscopic level and colorimetrically. A wider appreciation of the reasons for the present limitations of jet printing systems for textiles should help overcome misunderstandings between designers, specifiers and their customers alike.

Composition studies of [formula omitted] noise in RuO 2-glass films

Relative power spectral density S U U 2 of 1 f noise in RuO 2-glass films versus RuO 2 volume fraction v has been studied. Pastes that are binary mixtures of RuO 2 and glass powders with the mean particle sizes of 10 nm and 550 nm have been used. Films of different RuO 2 concentration v in the range from 0.06 to 0.28 have been produced by conventional screen printing and firing of the pastes deposited on alumina substrates. The firing was carried out at the peak temperature of 850 °C in the air atmosphere belt-type furnace. Noise power spectral density has been measured using cross-correlation technique in a measuring system based on Hewlett Packard Dynamic Signal Analyzer and personal computer to storage and process the noise signal data. Typical 1 f noise behavior with power spectral density inversely proportional to frequency and proportional to the square of the dc voltage U applied to the sample have been observed. The relative power spectral density of 1 f noise at 1Hz versus resistance per square has been analyzed in terms of the percolation power-law. Discussion of the 1 f noise models based on percolation and localization theories has been presented.

Fine‐line Passive Components for Hybrid Microelectronics

A laser ablation technique has been used to fabricate conductor patterns on a 96% alumina substrate to evolve passive fine‐line components and structures. This paper reports the method of fabricating better fine‐line passive components for hybrid microelectronics application. The effect of a laser beam on the conductor and 96% alumina (Al2O3) substrate was studied in detail. Three predominant structures — namely debris, ablation border and irradiated bottom layer — were seen on the patterns. A detailed study of the dendritic growth caused by electrochemical migration on conductor lines fabricated by conventional screen printing and by laser ablation techniques is also reported.

Amperometric glucose biosensor manufactured by a printing technique

A glucose sensor was fabricated using the screen printing technique with a special ink component containing ferrocene-bound glucose oxidase (fc-GOD). Glucose oxidase was modified with ferrocene derivatives as the electron-transfer mediator in order to obtain higher GOD activity. The ferrocene-modified GOD showed an increase in catalytic current. A special ink component compatible with the printing process was prepared with fc-GOD, soluble and insoluble polymer resins and organic solvent. Using the conventional screen printing technique, the ink component was printed on a thin gold film electrode on a plastic film. The output of the printed glucose sensor was observed to be stable for several hours and proportional to the glucose concentration from 0.5 to 2.0 mg ml −1.

Liquid Ink Jet Printing with MOD Inks for Hybrid Microcircuits

Application of the computer-controlled impulse ink jet with liquid metallo-organic decomposition (MOD) inks is demonstrated to be feasible in printing hybrid microcircuits. The advantages of ink jet printing over conventional screen printing are discussed. The hardware and software of the ink jet printing system have been developed. The MOD ink system suitable for the ink jet has been studied. Printing experiments with the ink jet have been conducted during the research. A theoretical model has been derived relating the ink jet flow rate to the primary spray control parameters. The ink jet system with silver neodecanoate MOD ink has been applied to metallize the grid pattern of silicon solar cells.