Direct printing of copper conductive micro-tracks by multi-nozzle electrohydrodynamic inkjet printing process

To overcome the limitation of low production speed of electrohydrodynamic (EHD) inkjet printing technology and to fabricate low cost electronic micro-structures, this paper presents the direct deposition of copper colloidal solution through the multi-nozzle EHD inkjet printing process. Multi-nozzle EHD inkjet printing head, consisting of five nozzles, was used for simultaneous printing of electrically conductive micro-tracks onto the glass substrate. Nozzle-to-nozzle distance and experimental conditions were optimized to prevent the interaction i.e., cross-talk between electrically charged neighboring jets. After sintering in inert (N₂ gas) atmosphere, printed tracks exhibited approximately five times larger resistivity (9.20 μΩ cm) than that of the bulk copper which is a remarkable achievement. These electrically conductive micro-tracks show the feasibility of multi-nozzle EHD inkjet printing technique using the copper nano-colloidal ink for low cost fabrication of microelectronic structures and devices.     

Pre-treatment by dry ice blasting for adhesive bonding

In recent years, the constant development of adhesives and coatings has contributed to the establishment of the adhesive and coating technology in several fields. Based on findings in macro-molecular chemistry, the cohesive strength, e.g. the internal strength of adhesives, has been enhanced continuously. In contrast to the adhesive strength, the mechanical, chemical and physical adhesion, the cohesive strength is relatively strong. As a consequence, adhesion is usually the weakest link of an adhesive bond, thus, most often it is adhesive fracture that can be observed. Pre-treatment and the use of so-called coupling reagents represent an approach to improve the adhesive strength. The paper presents dry ice blasting as a pre-treatment process and a process model with which the reasons for the increased adhesive strength can be clarified. With respect to the relevant blasting parameters, the effects of a pre-treatment with dry ice blasting on roughness, surface topography, specific surface, mechanical activation, surface energy and chemical composition depending on relevant parameters have been determined.     

Desktop inkjet printer as a tool to print conducting polymers

In order to exploit mechanical flexibility of organic-based electronic devices, conducting polymer anodes, such as polyaniline or poly(3,4-ethylenedioxy)-thiophene-poly(styrene sulfonate) (PEDOT-PSS), have been extensively studied. Along with the use of solution based processing techniques, conducting polymers can simplify the device fabrication procedure and yield themselves easily to printing techniques. In this paper, we present the results of utilizing desktop inkjet printer as a tool for direct printing and patterning of conducting polymer. Design of printable patterns and adjustment of printing parameters can be performed using any software such as Power Point. PEDOT-PSS suspension can be loaded into an inkjet cartridge and deposited on a given substrate in any designed pattern. The gray-scale color scheme can be employed to control the layer thickness and sheet resistivity of the inkjet printed layers. These layers are then used as anodes in organic light-emitting devices (OLEDs).     

激光胶接复合点焊工艺特性

分析激光胶接复合点焊工艺的稳定性,研究不同性能胶层的气体排出方式,解决激光胶接点焊工艺的焊接缺陷.结果表明,胶焊工艺的关键在于给胶层分解产生的气体合适的排气方式,胶层粘度越大,板间隙排气越困难,胶焊稳定性越差.对于低粘度的胶层,可以采用缓升激光脉冲工艺实现可靠连接;对于大粘度的胶层,采用尖峰激光脉冲加填丝的工艺才能实现可靠连接.这些焊接工艺能够解决不同粘度胶粘剂的胶焊工艺缺陷,扩大激光胶接复合点焊技术的应用范围.     

高速喷墨数字印刷机恒温恒压供墨系统设计

为了进一步提升喷墨印刷设备的性能,对供墨系统进行了研究。在分析供墨系统功能需求的基础上,提出了供墨系统墨路、液路、气路的设计方案,从硬件和软件角度详细讨论了该恒温恒压、具备清洗、点墨等附加功能的机电气液一体化的供墨系统,并通过实验验证该系统的有效性。目前该系统已经在喷墨数字印刷设备上投入使用,取到了满意的效果。     

Micropatterning of a stretchable conductive polymer using inkjet printing and agarose stamping

A highly conducting stretchable polymer material has been patterned using additive inkjet printing and by subtractive agarose stamping of a deactivation agent (hypochlorite). The material consisted of elastomeric polyurethane combined in an interpenetrating network with a conductive polymer, poly(3,4-ethylenedioxythiophene) (PEDOT). The agarose stamping produced 50 μm wide conducting lines with high spatial fidelity. The deactivation agent was found to cause some degradation of the remaining conducting lines, as revealed by a stronger increase in resistance upon straining compared to the pristine polymer material. Inkjet printing of the material was only possible if a short-chain polyurethane was used as elastomer to overcome strain hardening at the neck of the droplets produced for printing. Reproducible line widths down to 200 μm could be achieved by inkjet printing. Both methods were used to fabricate test patterns that allowed the electrical resistance parallel and perpendicular to the elongation direction to be measured. Electrical resistance increased both parallel and perpendicular to the direction of strain, with a faster increase observed parallel to the straining.     

Fabrication of high-resolution conductive line via inkjet printing of nano-palladium catalyst onto PET substrate

In this paper, a method to fabricate high-resolution conductive metal line on a flexible PET substrate is described. This method involves inkjet printing of a thermo-sensitive St-co-NIPAAm/Pd nanoparticle-based ink on an untreated polymer to create the catalytic site, onto which nickel is subsequently deposited by an electroless plating method, to obtain the desired width and conductivity of the metal line. The Pd nanoparticles reduced and stabilized by styrene-N-isopropylacrylamide co-oligomer showed their well dispersion in the water without surfactant and reductant in the mixture and these nanoparticles adhered well to untreated PET surface. Through a systematic study with a variety of inkjet variables such as firing voltage and droplet spacing, the optimum inkjet parameters were obtained. The adhesion of the deposited Ni-P coating to the substrate was ascertained by the scotch tape test method. The line width and electrical resistivity were examined as function of electroless plating time. The procedure was successfully applied for manufacturing high-resolution conductive metal line.     

不同参数对石膏3D打印模型性能的影响

通过正交试验研究了墨滴体积、层厚、分辨率、粉末目数对工业级石膏3D打印模型的抗拉强度、抗折强度、尺寸精度的影响,确定了石膏3D打印的最佳工艺参数:墨滴体积65 pL,层厚0.15 mm,分辨率0.06 mm,粉末目数150目,铺粉轴速度100 m/s,喷墨频率8000 Hz,负压31 MPa,振动电机频率108 r.按...     

Inkjet Printing of Amphotericin B onto Biodegradable Microneedles Using Piezoelectric Inkjet Printing

The delivery of amphotericin B, a pharmacologic agent with activity against a broad spectrum of fungi as well as against parasitic protozoa, has been complicated by the fact that amphotericin B exhibits poor solubility in aqueous solutions at physiologic pH levels. In this study, piezoelectric inkjet printing was used to modify the surfaces of Gantrez 169 BF microneedles (Ashland, Covington, KY). These amphotericin B-loaded microneedles demonstrated activity against Candida parapsilosis in a radial diffusion assay. The results of this study suggest that a combination of visible light dynamic mask microstereolithography, micromolding, and piezoelectric inkjet printing may be used to prepare amphotericin B-loaded microneedles with antifungal properties. It is envisioned that microneedles containing amphotericin B may be used for transdermal delivery of pharmacologic agents for the treatment of cutaneous fungal infections as well as cutaneous leishmaniasis.     

消失模粘结剂—热熔胶的研制

提出了消失模粘结剂———热熔胶应具备的主要性能；研制出了一种消失模铸造专用热熔胶，并测试了性能。     

Inkjet printed electrochemical organic electronics

A conventional desktop inkjet printer has been used as a combined deposition and patterning tool of electrochemical organic transistors on rough flexible carriers. The functionality of these devices rely upon redox reactions occurring at the interface between a conjugated polymer film and an electrolyte. Both the electrolyte and the conjugated polymer suspension (an aqueous dispersion of poly(3,4-ethylenedioxythiophene):poly(styrene sulphonic acid)) were additively patterned with the inkjet printer, making the electrochemical device all-inkjet printed. Basic implementations of the transistor in simple electrochemical logical circuitry have been produced. The printing technique can be anticipated to be used for the production of small series of devices based on the electrochemical technology discussed.     

Micropatterning of conducting polymer tracks on plasma treated flexible substrate using vapor phase polymerization-mediated inkjet printing

A facile strategy to pattern a conducting polymer on various flexible substrates is reported using vapor phase polymerization-mediated inkjet printing. Complex polypyrrole patterns were obtained via oxidation polymerization of vaporized monomer on the inkjet-printed oxidant patterns. The patterned lines are readily controlled by inkjet printing with the high resolution of micrometer scale. FT-IR attenuated total reflection analysis and X-ray photoelectron spectroscopy were conducted in order to confirm the polymerization of pyrrole monomer. This process provided highly conductive polymer patterns of polypyrrole with the sheet resistance of 2.8 × 10³ Ω/□, the minimum line width of ca. 60 μm and the film thickness of ca. 450 nm. Furthermore, metallic copper pattern was prepared on previously patterned polypyrrole architectures by electroless plating as a practical application.     

Challenges in drop-on-drop deposition of reactive molten nylon materials for additive manufacturing

An inkjet-based additive manufacturing process must overcome a variety of challenges including uniform layer fabrication, especially when the process involves deposition of multiple materials in each layer. Research is being conducted into a novel process to synthesise nylon 6 via inkjet printing of two reactive mixtures consisting of molten caprolactam with an activator and a catalyst. Jettability of the materials has been reported while this paper presents the results of drop-on-drop deposition of the molten materials. Droplet/surface interactions, formation and stability of beads, droplet placement accuracy and drop-on-drop mixing are reported. Results show that although spreading occurred during impingement, the first five droplets produced a bulge at the start of the bead. The bead was then observed to be uniform with further droplet impingement on heated and cold surfaces. However, it did not retain the stability on a heated surface and bulges and ridges developed within a second. Drop-on-drop placement was not accurate when using the catalyst mixture. This was because the undissolved catalyst complex (in form of microcrystals) agglomerated and it was possibly this that disturbed the meniscus at the nozzle and led to a jet trajectory error. Repeated drop-on-drop deposition confirmed that the impingement kinetics provided mixing which is crucial to produce nylon.     

Characteristics on micro-biofabrication by patterning with electrostatically injected droplet

Micro biofabrication technologies have been developing aiming to fabricate 3D artificial organs, 3D scaffolds, and complex tissue structures. We are now developing a new inkjet bio-printing method via electrostatic phenomenon. The merits of the new method are of high resolution, and of ability to eject highly viscous liquid and media. In this paper, we attempted to apply the proposed method for precision printing cells and biomaterials. Living cells and scaffolds have successfully been printed and the biochemical characteristics have been investigated. A 3D cell structure which had a cavity to create blood vessels has also successfully fabricated by this method.     

Use of thin adherends in adhesively bonded joints under different loading modes

Abstract

The adhesive bonding technique is especially suited to the joining of thin materials. An adhesive joint consists of a structural adhesive and an adherend. When designing the joint, focusing on the behaviour of the adhesive is important. However, if the material to be joined is thin, then it becomes much more important to concentrate on the material properties. In the present work, two adhesives with different mechanical behaviour and two thin adherend materials, steel and aluminium, were selected for the production of adhesive joints. The single lap joint configuration was subjected to tests under bending load and also under tensile load. The results show that adherend plasticity plays an important part in the joint failure; specimens under bending load experienced high plastic deformation of adherends, depending on the strength of the adherend material. Overlap increase did not seem to affect the joint strength. When the joints were tested under tensile loading, it was observed that the load bearing capacity of adhesives was an important parameter influencing the joint strength, and that an increase in overlap seemed to contribute to the joint performance. In general, the results obtained imply that it is vital that the adherends used remain in their elastic deformation region to obtain a joint strength that reflects the mechanical behaviour of the adhesive used.     

Printed gold for electronic applications

Molecular and nanoparticulate gold precursors for application in inkjet printing onto flexible substrates are discussed. The choice of stabilising ligands and the size of the nanoparticles influence the solution stability of the ink and their ability to form decorative or conductive functional films.     

基于电机挤出沉积的多喷头生物3D打印系统

3D打印载药组织工程骨支架正朝着多材质方向发展。针对多材质支架打印过程中出现的多喷头切换时产生的喷头干涉碰撞、共点打印以及流涎现象,对电机挤出式打印喷头的切换装置、多材质打印路径及多喷头打印控制进行研究,提出基于电机挤出沉积的多喷头打印系统及多喷头控制方法。使用花瓣形喷头切换机构实现多材质的切换,设计多喷头切换的路径规划方法及上位机控制程序,最后以羟基磷灰石和聚乙烯醇的混合材料在多喷头生物3D打印系统上进行打印测试。研究结果表明：该系统能实现多喷头的协调打印、共点打印,解决了打印过程中喷头切换时产生的干涉碰撞和流涎现象,为仿生载药组织工程骨支架的梯度打印提供了参考。     

Untersuchungen über das Kleben von Blei

Investigations into adhesive lead joints Lead plate thoroughly prepared for adhesive joining can be connected with other materials with the aid of resin-based adhesives. Picked surface yield higher strengths in the adhesive joint than do surface roughened by mechanical action. Hot-curing epoxy-based adhesive on picked surface yield adhesive strengths superior to the cohesive strength of lead as established in the tensile test. Adhesives requiring high compressive loads for curing, or adhesives based on vinyl resins are not suitable for use with lead. Overlapping joints may neutralize just small fractions of the tensile shearing forces. In such cases lead will become detached from the adhesive layer because of its high degree of deformation. At elevated temperatures, however, the adhesive strength of the adhesive on lead is often superior to the shearing strength of the joint; as a consequence thereof, the lead itself will fail. Adhesive joints with lead can bear temperatures up to 70°C for a long time without any loss of strength. Glass fibre roving embedded in the adhesive layer may increase the tensile strength and yield advantages as far as processing technology is concerned. Lead-coated parts may be deformed even after adhesive joining.     

Numerical studies on the stress distribution in weldbonded joints with different adhesives

The Effect of elastic modulus and thickness of the adhesives on the stress distribution in weldbonded joints hasbeen studied with three-dimensional elastoplastic finite element method (FEM). Stress distribution curves have beenobtained at the edges of the spot welds and the lap zones in weldbonded joints, which werem made with adhesives ofdifferent elastic modulus or different thickness. Results show that there exists larger stress concentration at the edge of thespot Welds, though the shear stresses in the adhesive layers are smaller for weldbonded joints with low elastic modulus orthick adhesive layers. the stress concentration decreases and the shear stresses in adhesive layers increase with the increaseof the elastic modulus or the decrease of the adhesive thickness. It is concluded that the thiner adhesive layers with higherelastic modulius are preferable in weldbonded joints to cut down the stress concentration.     

零件表面二维喷码的最佳工艺参数研究

本文主要研究了零件直接标识技术中喷码标印二维条码的工艺参数优化问题,选取铝合金(LD10CZ)板材作为标印材料,将喷码标印的工艺参数(墨水压力值、调制电压、喷头高度、传送带速度)作为优化变量,标印的二维条码质量(对比度、打印增长、高宽比例)作为优化目标,通过均匀试验设计和二次多项式逐步回归方法,研究了各工艺参数及其交互作用对优化目标的影响规律和显著性程度。获得了最佳的工艺参数组合并实验验证,提高了二维喷码的质量,对工程应用有重要意义。