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ICMCTF2008 Session EP: Symposium E Poster Session

Thursday, May 1, 2008 5:00 PM in Room Town & Country

Thursday Afternoon

Time Period ThP Sessions | Topic E Sessions | Time Periods | Topics | ICMCTF2008 Schedule

EP-2 The Analysis of the Adhesive System Used for Bonding Polyimide and Copper Foil in the Flexible Circuit Board M.T. Yeh (Yuan-Ze University, Taiwan) The adhesive properties and durability of the modified epoxy adhesive system used for building polyimide flexible circuit substrate are studied with differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, attenuate total reflection infrared spectroscopy (ATR), and peel strength measurement. It is obtained that the curing condition and the modifier have a significant effect on the curing compositions and the properties of the formulated adhesives. The preferential adsorption of the modifier onto the copper surface is found and affected by the curing condition and the subsequently thermal exposure. Additionally, the degradation of the adhesive resins is accelerated by the copper surfaces in contact. As obtained from the analyses, all formulated flexible adhesive systems have good peel strength and durability on the copper substrate, and have good storage stability for over six months.
EP-3 Nano-Lamination in Amorphous Carbon for Tailored Coating in Micro-Dry Stamping of AISI-304 Stainless Steel Sheets T.A. Aizawa (Osaka Prefecture University, Japan); E.I. Iwamura (Arakawa Chemicals Co. Ltd., Japan); K.I. Itoh (Seki-Corporation Co. Ltd., Japan) With down-sizing of electrical products and goods, huge amount of small-scaled and miniatured electrical parts are fabricated by fast-rate stamping. Since residual lubricating oils and cleansing agents are completely disliked by these tiny parts, this type of micro-stamping must be done in dry or without use of lubricating oils. In industries, half of electrical parts are made from austenitic stainless steel AISI 304 sheets. Hence, both coated tools and dies with sufficient wear-toughness are indispensable to put micro-dry stamping into practice. First candidate is a hard coating by DLC (diamond-like carbon) or amorphous carbon like a-C:H or Si-/W-DLC's. Since this type of coating has insufficient scratching strength, the coated tools and dies often suffer from delamination in the early stage of micro-dry stamping with severe clearance set-up. Nano-lamination is a new way to make full use of multi-layered structure for coating instead of the mono-layered coating system. Different from the conventional nano-lamination method, where two different kinds of material system are deposited in layers, the developed nano-lamination is based on the carbon deposition. Controlling the bias voltage program sequence, amorphous carbon layer by a-C:H is alternatively deposited with graphite-like cluster layer, resulting in a carbon-origin nano-laminated coating. The most preferable feature of this coating lies in the fact that hardness and related mechanical characteristics are controllable by varying the periodicity of this layer and sublayer-ratio in the unit layer for nano-lamination. In this paper, the effect of sublayer-ratio in this tailored coating on the hardness is investigated by nano-indentation technique. Higher hardness can be attained by controlling the sublayer-ratio as well as periodicity. Next, the scratching test of this tailored coating is made to demonstrate that each coated tool has sufficient scratch load above 100 N. Furthermore, a micro-dry stamping test is performed to prove that this nano-laminated coating has sufficient wear-toughness enough to make dry stamping in 10000 times or more in practice. No delaminations nor break-away occurs on the ironed surface of coated tools while severe delamination is observed in the conventional mono-layered coating.
EP-5 Characteristics of Microcrystalline Silicon Thin Films Deposited by Using Internal Linear-Type Inductively Coupled Plasma-CVD H.C. Lee, H.B. Kim, G.Y. Yeom (Sungkyunkwan University, Korea) Nanocrystalline and microcrystalline silicon thin films are widely used in the electronic and optical devices, such as thin film transistors (TFT), solar cell, and image sensors. In addition, due to its higher carrier mobility compared to that of amorphous silicon film, these crystalline silicons have great potentials in the application to active matrix organic light emitting diode (AMOLED). Inductively coupled plasmas (ICP) have been investigated for the processing of various materials as one of the high density (10¹¹~10¹² cm^-3) and low gas pressure plasma sources. Especially, ICP is one of the most attractive source among the various high density plasma sources due to the advantages of simple physics and a simple source structure. In this study, we prepared hydrogenated microcrystalline silicon thin films at various working pressures and gas mixtures deposited by internal linear antenna type plasma enhanced chemical vapor deposition method. The microcrystalline silicon thin films were deposited on glass (corning 1737), silicon dioxide, and single-crystal Si. The film properties were characterized using Raman scattering spectroscopy, scanning electron microscopy (SEM), I-V measurements to evaluate film crystallinity, structural image, and photo-dark conductivity, respectively. Crystalline silicon having the size of ~15nm could be deposited and the volume fraction of the crystalline obtained by the Raman spectroscopy was higher than 35%.
EP-7 The Tribological Properties of Vehicle Power Engines Applied with Composite Zirconium Diamond-Like Carbon Film C. Lin, C. Su, C. Chang (National Taipei University of Technology, Taiwan) The Tribology has for long been the key determinant of efficiency loss on vehicle power engines. This research conducts analysis over the tribological properties of aluminum alloy (AC8A-T6) vehicle engines by depositing composite zirconium diamond-like carbon film (DLC-Zr) on the engines through double magnetron sputtering technology. The result shows that zirconium metal elements can effectively eliminate the stress in the diamond-like carbon (DLC) film and alter the structure to enhance the film rigidity. Based on dynamic analysis, it is found that zirconium diamond-like carbon film can be used to improve the abrasion-resistant performance obviously. The amount of wear of materials used to make aluminum alloy engines is reduced from 33um to less than 1.1um.
EP-8 Development of Zirconium Oxynitride Thin Films on Si(100) by HCD-IP System and Heat Treatment S.-J Wang, J.-H. Huang, G.-P. Yu (National Tsing Hua University, Taiwan) The zirconium oxynitride thin films have good mechanical properties and decorative coloration for the industry. With high enough oxygen content during deposition, the Zr₂ON2 thin films were found after heat treatment. The research tried to obtain the effect of increasing O/N ratio to the structure and properties of zirconium oxynitride thin films to form stable Zr₂ON2 structure after heat treatment. The niridation of ZrO₂ thin films were the firstly deposited on p-type Si(100) substrate by using hollow cathode discharge ion-plating (HCD-IP) system. The oxygen flow rate was the single-variables. The zirconium oxynitride thin films were investigated with as-deposited and heat treatment the samples. The main purpose of the work was focus on investigating the process parameters to form zirconium oxynitride thin films instead of ZrO₂ and ZrN mixture. After deposition, the thickness of the thin films was measured by scanning electron micros ropy (SEM). The preferred orientation was characterized by X-ray diffraction (XRD), and the grain size of the thin films was calculated by the Scherrer equation. The O/N ratio and binding energy were determined by the X-ray photoelectron spectroscopy (XPS). The corrosion resistance of thin films was evaluated by salt spray test and potentiodynamic scan. The hardness of the thin films were obtained by a nanoindentor. The structure of Zr₂ON2 thin films was derived from m-ZrO₂ with nitrogen defects. The hardness decreased substantially with increasing oxygen content. The band gap of Zr₂ON2 was narrower than ZrO₂.The correlation between structure and properties is discussed in this paper.
EP-9 Characterization of Amrophous and Crystalline Metallic Glass Thin Films Deposited by Unbalanced Magnetron Sputtering System C.-C. Tsai (National Tsing Hua University, Taiwan); P.-K. Liaw (The University of Tennessee); J.-H. Huang, G.-P. Yu (National Tsing Hua University, Taiwan) The ZrCuAgAl metallic glass film was deposited on p-type (100) Si substrate and 304 stainless steel by unbalanced magnetron sputtering system (UBM). The Zr₄₃Cu₄₃Ag₇Al₇ material was traditionally used to fabricate the bulk metal glass (BMG). The Zr-based and Cu-based BMGs have exhibited extremely high glass-forming ability and have demonstrated good properties such as high yield strength, hardness, corrosion resistance, wear-resistance, good thermal conductivity and electrical conductivity. Previous reports indicated that the amorphous phase is more resistance to pitting nucleation and the crystalline one is more resistance to pitting propagation due to lower chemical potential. The mechanical properties of the BMGs, such as the elastic modulus and hardness, are the function of the Zr (or Cu) concentration. Much research has focused on BMG, while little work has been reported on metallic glass thin film. In this research, to investigate the influence of the structure of the metallic glass thin film on the mechanical, electrical properties and corrosion behavior, the amorphous and crystalline films were deposited at room temperature and at elevated temperature respectively. The structure of ZrCuAgAl films were determined using X-ray diffraction (XRD). The thickness of thin film was measured by scanning electron microscopy (SEM). The Hardness of the film was measured using nanoindentation (NIP). Atomic force microscopy (AFM) was used to determine the surface morphology and roughness. The composition of the film was obtained by X-ray photoelectron spectroscopy (XPS). Auger electron spectroscopy (AES) are used to obtained the composition depth profile of thin film. The packing factor was calculated by the data from Rutherford backscattering spectroscopy (RBS). The corrosion resistance of ZrCuAgAl films was evaluated by potentiodynamic scan. The color of thin films was silver and the electrical resistivity was quite low. Amorphous metallic glass thin films had good corrosion resistance in aerated 0.5M H₂SO₄ + 0.05 KSCN solution and 5%wt NaCl solution.
EP-10 Determination of Young's Modulus and Poisson's Ratio of Thin Films by Combining Modified sin²ψ X-ray Diffraction and Laser Curvature Methods J.-Y. Chang, J.-H. Huang, G.-P. Yu (National Tsing Hua University, Taiwan) For the traditional sin²ψ X-ray diffraction method, the inaccuracy of the elastic constants E/(1+ν) introduces the largest error in stress measurements and hence Young's modulus and Poisson's ratio should be determined by XRD method to increase the accuracy. Due to the restriction of thin film specimens, it is difficult to determine E and ν using a tensile stage on diffractometer. Most of the other methods require either E or ν is given in order to resolve the other. In this study, we propose a non-destructive technique to simultaneously determine the two constants. The concept is to independently measure strain components by modified sin²ψ XRD method and residual stress by laser curvature method. Then E and ν can be calculated using linear elasticity theory. An asymmetrical geometry with grazing incidence X-ray is adopted in the cos²α sin²ψ method and a specific diffraction peak is measured from a series of tilt-angle ψ and incident-angle γ to determine the lattice spacing such that the six strain components may be solved. The analysis reveals the evaluated strains follow a linear relationship with the parameter cos²α sin²ψ, in the same way as with the parameter sin²ψ in the sin²ψ method. Both sin²ψ and cos²α sin²ψ methods have been applied to thick TiN films and ZrN films for comparison, and then a thin TiN film will be used to validate the cos²α sin²ψ method. This combination of X-ray diffraction and laser curvature methods has proven to be a feasible way for determining the values of E and ν.
EP-11 Influence of Plasma Nitriding Treatment Time on the Load-Carrying Capacity of AISI 4140 Steel in Duplex Plasma Diffusion/PVD-Coating Systems S. Goulart-Santos, C. Godoy, R.D. Mancosu (Universidade Federal de Minas Gerais, Brazil); A. Leyland, A. Matthews (University of Sheffield, United Kingdom) Substrate softening has been identified as one of the most influential factors on the performance of nitrided/coating duplex treatments and was already investigated by varying the plasma nitriding temperature in tool steels, high carbon and low alloy steels. In this work, the influence of the plasma nitriding treatment time on the load carrying capacity was investigated. An AISI 4140 steel was nitrided using two different periods of time, being 2 and 4 hours, at 500°C, in a 60%H₂-40%N₂ atmosphere. The subsequent Cr-Al-N coating deposition was carried out by plasma-assisted PVD. Metallography was used to observe in cross-section the nitrided AISI 4140 steel and the nitrided/coating duplex systems. The systems were also characterised by Rockwell C adhesion tests and X-ray diffraction, the surface roughness was assessed using profilometry. The surface hardness, i.e., the composite hardness of the duplex layer and substrate, at different indentation loads was assessed by ultra-micro Berkovich and micro Vickers indentation. Ultra-micro hardness results indicated that, although there were increases in the near-surface hardness for both nitriding treatments, there was an unexpected decrease in hardness at high loads for AISI 4140 steel nitrided for 4 hours, suggesting substrate softening in the longer plasma nitriding treatment. The hardness in cross-section was also measured. The difference in the nitride layer depth profile for both nitriding periods is discussed. Both treatments were submitted to a cavitation erosion test to investigate how the different load carrying capacity of the nitrided steel could affect the performance of duplex coatings.
EP-14 Control of Magnetron Sputtered MoS₂ Coating Orientation in Mid-Frequency Pulsed Deposition Processes C. Muratore (Air Force Research Laboratory (AFRL/RXBT)/UTC, Inc.); A.A. Voevodin (Air Force Research Laboratory) Molybdenum disulfide was grown under selected mid-frequency bi-polar pulsed dc power conditions to observe the effects of duty factor, frequency and reverse time on the structure and properties of the sputtered material. At high frequencies (=200 kHz) the power supply was incapable of achieving the nominal duty factor, resulting in a reduced deposition rate. High duty factors at frequencies of 75- 85 kHz yielded coatings with the largest (002)/(100) orientation ratios (5). Under these conditions, the kinetic energy of argon ions incident on the substrate was measured with an electrostatic plasma analyzer to be as high as 175 eV over the course of one magnetron pulse, which was at least 50 eV higher than that recorded for the other frequencies and duty factors explored here. The increased ion energy efficiently produced defects on the otherwise inert [002] molybdenum disulfide surface, thereby facilitating the growth of crystals with basal planes oriented parallel to the substrate. For duty factors = 60 percent, growth rates of less than one monolayer per second were observed, which were lower than expected based on the reduction of duty factor alone. Under these conditions, the desorption time of chemisorbed species on the surface was less than the time required to bury the deposited atoms with coating material, thus resulting in an additional mechanism by which the deposition rate was lowered. Coatings grown at low rates did exhibit strong (100) orientation due to comparatively rapid adsorption rates on the reactive crystal edge planes. The effect of coating orientation on tribological performance was demonstrated with sliding wear tests in humid air. Coatings with the highest (002)/(100) ratios demonstrated the lowest friction and wear rates, which varied monotonically with the fraction of crystals with basal planes oriented parallel to the substrate.
EP-15 Tensile Testing Experiments of Photocatalytic TiO₂ Thin Films Deposited on Polymer Substrates C.J. Tavares, S.M. Marques, S. Lanceros-Mendez, V. Sencadas, C.M. Costa (University of Minho, Portugal) Titanium dioxide is a well known photocatalyst for its efficiency in dissociating pollutant organic compounds that are adsorbed on a particular surface. Polymer substrates have found their way in the semiconductor industry as a base layer for electronics and devices in nanotechnology as well as in sensor and actuator applications. The manipulation and use of these systems have the adverse side of dirtiness, hindering for times its correct functioning and also possibly cause the degradation of the polymer. Enhancing the photocatalytic efficiency and the mechanical properties of titania has become a major concern for the authors. TiO₂ thin films have been deposited by unbalanced reactive magnetron sputtering from a high purity Ti target in an Ar/O₂ atmosphere, at room temperature on polymer sheets, such as PVDF, Polycarbonate and TrFE. The photocatalytic behaviour of the titania coatings was determined by combined ultra-violet irradiation and absorption measurements. The observed photo-decomposition of the aqueous solution (organic dye), acting as a pollutant, was measured in the UV/Vis spectrum by the decrease of the maximum absorbance with irradiation time. Analysis of the absorption data allowed us to obtain the decrease in concentration as a function of time to be observed. In order to assess the mechanical behaviour of the as-sputtered films, the film/substrate composite system was loaded unidirectionally using a tensile testing machine. The relation between the measured crack density and the applied strain has been used to characterize the film strength and relate it with the titania photocatalytic efficiency.
EP-17 Surface Texturing by Using Reactive Ion Etching for Adaptive Solid Lubricant P. Basnyat, B. Luster, S. Aouadi (Southern Illinois University Carbondale); C. Muratore (Air Force Research Laboratory (AFRL/RXBT)/UTC, Inc.); A.A. Voevodin (Air Force Research Laboratory); P. Kohli (Southern Illinois University Carbondale) The production of surface micro-patterns that are used as reservoirs for solid lubricants was recently shown to provide improved wear and frictional properties in sliding contact. We report on the fabrication of micrometer-sized dimple patterns of different sizes on TiAlCN and CrN hard coatings produced by unbalanced magnetron sputtering using reactive ion etching. The dimples were subsequently filled with solid lubricants based on MoS₂ and Mo-MoS₂-Ag over the micro-textured surfaces by magnetron sputtering. The tribological properties of the coatings were investigated in dry sliding at 25°C, 350°C, and 600°C against Si₃N₄. The coatings and respective wear tracks were examined using scanning electron microscopy (SEM), optical microscopy, profilometry, energy dispersive x-ray spectroscopy (EDX), and micro-Raman spectroscopy. The frictional and wear properties with solid lubricant films deposited on textured and flat surfaces were compared. A significant decrease in friction and wear coefficients was achieved with the textured architecture. The chemistry and phase analysis of coating contact surfaces showed temperature adaptive behavior with the lubrication being provided primarily by MoS2 and silver at 25°C, 350°C and silver molybdate compounds at 600°C tests.
EP-18 Tribology and Mechanical Behavior of CrN / a - CN Superlattice Thin Films Y.J. Kim, T.J. Byun (Sungkyunkwan University, Korea); H.Y. Lee (Cheorwon Plasma Research Institute, Korea); J.G. Han (Sungkyunkwan University, Korea) PVD hard coatings exhibit combined properties such as high wear and oxidation resistance. In recent years, an industrial interest in hard coatings has been focused on further improvement of their chemical and mechanical properties. Improved coatings can be achieved by understanding the coating structure: the superlattice-structured thin films have been recently developed by many researchers. However the basic understanding of tribological properties of nanoscale multilayered coatings is still not established yet^1,2. In this study, the CrN / a - CN superlattice thin films, which were a superhard coating with lamination of hard transition metal nitride and lubrication material, are synthesized by Closed Field Unbalanced Magnetron Sputtering (CFUBMS). The bilayer period (?) ranging from 3.1 to 37.7 nm is controlled via rotational speed of the substrate holder . The preferred orientation of the CrN / a - CN superlattice thin films is CrN (200). Nano-indentation testing show that the mechanical properties of the coatings ranging from 20 to 32 GPa varied with the bilayer period (?). Especially, the highest hardness is evaluated with the bilayer period of about 6.3 nm. In this case, friction coefficient is also obtained lowest value due to high plastic deformation resistance.

Time Period ThP Sessions | Topic E Sessions | Time Periods | Topics | ICMCTF2008 Schedule