bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solvent Induced Crack-Like Defects in Adhered Polyimide Films
Authors: Yang A. C. M. , Brown H. R. 
Published: March 2011

AbstractWhen thin adhered films of a polyimide (Ciba-Geigy XU-293) on rigid substrates are immersed in xylene, defects, that look like cracks to the naked eye, are formed. These defects are caused by the presence of the combination of the equibiaxial tension in the film and the xylene. The stress comes from the solvent loss and the thermal expansion mismatch between the substrate and the film. The defects are found to be local deformation zones, showing considerable optical anisotropy and a microstructure strongly influenced by the adhesion condition to the substrate. Although they retain a smooth surface on the face in contact with the substrate in the bonded regions, the deformation zones release a significant amount of stress. The stress released is measured by a photoelastic technique and is found to be in excellent agreement with that calculated from the local thickness change assuming simple elasticity. These deformation zones grow at a speed that is independent of their length and initiation time but increase rapidly with film thickness from a threshold at a thickness of about 3 microns. The observed thickness effect can be explained by a fracture mechanics analysis of adhered films where, unlike the case in free films, the energy release rate, G, is independent of crack length but varies with film stress and linearly with film thickness.
Predictive Design of Multicomponent Polymers for Printed Circuit Boards
Authors: Beuhler A. J. , Wrezel J. A. , Maas J. L. , Sundahl R. C. 
Published: March 2011

AbstractThe most common structural and dielectric materials for printed wiring boards are polymer composites such as epoxy/fiberglass and polyimide/fiberglass. The light weight, low cost, processability, and low dielectric constant of these materials make them particularly suited for this application.
Fluorination of Polymeric Films by a Non Equilibrium Plasma at an Atmospheric Pressure
Authors: Rouzbehi F. , Amouroux J. , Goldman M. 
Published: March 2011

AbstractThe polymerization of I-I difluoroethylene has been realized by a non equilibrium plasma at an atmospheric pressure on polymeric substrates such as polypropylene (PP). The graft copolymerizat ion onto the PP film was carried out when activating the polymeric substrate in the presence of argon. The structure of the polymeric film obtained depends on the residual oxygen in the plasma reactor. The role of the radicals which interfere in the grafting mechanisms of monomers onto polypropylene films has been studied.
Laser Photoetching of Polymers
Authors: Cole H. S. , Liu Y. S. , Philipp H. R. , Guida R. 
Published: March 2011

AbstractLaser photoetching of polymers has been shown to be a useful method of producing via holes or patterns and is of potential importance in microelectronics fabrication. The maskless, self-developing nature of the process also offers unique opportunities in the preparation of packaging assemblies. Etching of via holes at any discretionary site for multichip interconnect, for example, provides the circuit designer with additional design flexibility. The photoetching rate is dependent on the absorption coefficient of the polymer (at the laser wavelength) and the irradiating fluence. Further, there appears to be an optimum absorption coefficient to achieve the maximum photoetch rate for a given fluence level. To laser drill holes for interconnects, it is desirable to irradiate at the highest energy (increased rate) possible without damaging underlying metal contact pads.
Metal Atom Reactions with Polymer Films
Authors: Kovac Caroline A. , Jordan Jean L. , Pollak Roger A. 
Published: March 2011

AbstractThe chemical nature of the interface formed when an electropositive metal (chromium) is evaporated on the surface of oxygen-containing polymers has been investigated by synchrotron-radiation excited photoemission spectroscopy and by near-edge X-ray absorption fine stnrcture spectroscopy (NEXAFS). PMDA-ODA polyimide was studied along with two polymers intended to more simply model the complex chemical functionality of polyimide. Core-level spectra were resolved into distinct peaks, which were assigned to specific atoms in the polymer units, and changes in the spectra were monitored as chromium metal atoms were evaporated onto the surface. Similarly, NEXAFS spectra were taken as a function of chromium deposition. Results of these experiments show that chromium initially reacts very rapidly with surface carbonyl groups, but less strongly with ether oxygens or arene rings. In all polymers studied, formation of an electron-rich, carbide-like species was observed.
Interconnection Trends and Impact on Materials
Authors: Knausenberger W. H. , Pinnel M. R. 
Published: March 2011

AbstractRapid technological advances in electronic systems technologies are placing increasingly severe demands on interconnection media. One primary driving force is the evolutionary advance in the scale of integration in silicon with its inherent cost and performance advantages. A second key driving force is the revolutionary development of photonics which is rapidly integrating into most levels of the interconnection heirarchy. The performance of large scale electronic systems will be increasingly dominated and limited by their interconnection environment. To sustain the present rate of growth in the performance of future systems, new technology directions in interconnection will be necessary.This paper will explore the traditional levels of interconnection from IC chip packages to the frame level. It will be shown how the various levels of interconnection interrelate and how all levels must be improved simultaneously to achieve the full performance and cost benefits offered by device advances and photonics. The first major step in this evolution is well underway with the rapid transition to surface mounting of devices. This places new demands on materials and assembly technologies which will be discussed. However, the demands of this first step may eventually appear to be minor compared to those yet to come if current trends continue. Several scenarios for this future will be considered and related to the challenges placed on interconnection technology hardware and materials in terms of performance characteristics such as density, speed and heat dissipation.
Metal-Metal Interactions of Importance to Electronic Packaging
Authors: Chang Chin-An 
Published: March 2011

AbstractMetal-metal interactions have been of vital importance to various technologies, including packaging of electronic materials. Extensive interdiffusion and outdiffusion can lead to undesired alloy formation, and oxide formation on the surface which can hinder subsequent bonding processes. Furthermore, the interactions can be profoundly affected by the ambient gases used, either in the joining process or during subsequent storage and operation. One therefore needs a specially designed metallurgy, a diffusion barrier layer, or a proper ambient to deal with such concerns. The effects of ambient and diffusion barriers on the metal-metal interactions are described. Examples are illustrated where extensive interactions across the diffusion barrier are observed, and their impact on the packaging applications discussed.
Discussion of Wetting Phenomena Under Reducing Atmospheres Using a High Resolution Wetting Balancem
Authors: Jahnke B. , Reiss H. 
Published: March 2011

AbstractIn wetting phenomena surface and interfacial energies play an important part. Due to diffusion, precipitation and adsorption processes these energies are time and temperature dependently changing. The influence on wetting behaviour is investigated using a high resolution wetting balance and metallographic inspection.
Properties of E-Beam Interactive Oxide Films
Authors: Hollenbeck J. L. , Buchanan R. C. 
Published: March 2011

AbstractDeposition of E-beam interactive films by rf sputtering and their behavior under high intensity irradiation was investigated. Both polycrystalline and amorphous films of SiO2, ZrO2, Al2O3, and Y2O3were deposited and their behavior under irradiation found to-be strongTy dependent on film structure. Using a modified STEM the formation of small holes (<10nm diam.) was achieved with exposure times in the millisecond range. Deposition parameters, film characteristics, drilling behavior, and a possible mechanism are discussed.
The Effect of Hydrolysis Conditions on the Characteristics of PbTiO3 Gels and Thin Films
Authors: Budd K. D. , Dey S. K. , Payne D. A. 
Published: March 2011

AbstractSol-gel processing represents a promising method of fabrication for thin films of electronic ceramics which are useful in a number of packaging and device applications. In this study, the influence of acid and base catalysts on the structure of PbTiO3 gels and films (0.1-1.0μm) was investigated, for the purpose of inducing and identifying gel structures which were the most suitable as precursors for thin dielectric layers. Continuous, crack-free films, with dielectric strengths in excess of 106 V/cm were developed. Basic solutions gelled rapidly, phase separated, and were probably more crosslinked than acidic gels. Acidic gels seemed more capable of polymeric rearrangement during drying, yielding denser amorphous structures with microcrystalline regions. High-field dielectric constants (1 MV/m ac) in the range K=30–40, and K=160–170, were determined for amorphous and crystalline films, respectively.
Chemical Processing of BaTiO3 Based ceramics
Authors: Rehspringer J. L. , Bernier J. C. 
Published: March 2011

AbstractFor multilayers capacitors, submicron BaTiO3 powders are synthetised by chemical routes including gels. Three routes are described, oxalate precipitation, alkoxide gels and carboxyalkoxide polymerisations. Powders characteristics, relations between grain sizes, agglomerates, sintering capabilities and dielectric properties are discussed
Multilayer Ceramic Capacitors Based on Pb(Mg1/3Nb2/3)O3
Authors: Bouquin O. , Lejeune M. , Boilot J. P. 
Published: March 2011

AbstractMultilayer capacitors were made from Pb(Mg1/3Nb2/3)O3 compositon by an usual technique: ceramic green sheets formed by slip casting method, printed with an 70% wt Ag- 30% wt Pd internal electrode and sintered at temperature ranging from 950 to 11OO°C. Chip capacitors exhibit large capacitance and temperature characteristics meet Z5U specification. Electrical properties of MLC based on PMN depend on specific parameters such as the average concentration of pyrochlore phase and perovskite phase, and the homogeneity degree of dielectric layers. Load humidity life tests show a degradation of some chips which can be connected with the formation of a surface layer rich in pyrochlore phase.
Small Angle Neutron Scattering Studies on Miscibility of Polystyrene and Tetramethyl-Bisphenol A-Polycarbonate Blends
Authors: Yang Hsinjin , O'Reilly J. N. 
Published: March 2011

AbstractThe miscible blend of polystyrene (PSH) and tetramethyl-bisphenol A-polycarbonate (TMPC) has been previously studied by differential scanning calorimetry (DSC), viscoelasticity, and microscopy. In this study, small-angle neutron scattering (SANS) has been applied to obtain the quantitative interaction parameter (X) of this blend at room temperature. Deuterated polystyrene (PSD) was used for the scattering contrast in the study. The PSD/TMPC blends show a single Tgover the whole range of composition from the DSC measurements, whicg is the same as the Tgof PSH/TMPC blend.The interaction parameter was calculated from the de Gennes scattering intensity function of miscible polymer blends, which is based on the random phase approximation. As expected for a miscible system, all X values are negative over the range of composition. It is also found that the X is composition-dependent. Furthermore, the correlation length of the concentration fluctuation is approximately twice the segment length 21–32 Å of the component polymer (PSD = 6.7 Å and TMPC = 18.3 Å), implying that the mixing of this blend is effectively at segmental level.
Small-Angle X-Ray Scattering Study of Microand Macro-Phase Separations in Blends of Block Copolymer with Homopolymer
Authors: Roe R. J. , Nojima S. 
Published: March 2011

AbstractThe order-disorder phase transition behavior exhibited by blends of a styrene-butadiene diblock copolymer (76% styrene) with a polystyrene of various molecular weight (from 2,200 to 50,000) is studied by means of small-angle X-ray scattering. With a polystyrene of a relatively short chain length the blend, on lowering the temperature, undergoes a microphase separation, and the scattering curve shows a peak at a finite scattering angle. With a polystyrene of relatively long chain length, the scattered intensity curve shows additional low angle component with intensity increasing rapidly as q→0, and this is interpreted in terms of the macrophase separation accompanying the transition from the disordered to ordered phase.
Exafs Analysis of Ionomers
Authors: Ding Y. S. , Pan H. K. , Régister R. A. , Cooper S. L. 
Published: March 2011

AbstractExtended x-ray absorption fine structure (EXAFS) spectroscopy has beensuccessfully applied to the analysis of the ionic domain microstructure inzinc and rubidium neutralized ionomers. In dehydrated zinc neutralizedionomers, the zinc cation was found to be tetrahedrally coordinated to oxygenatoms. For ionomers with hydrocarbon backbones, these oxygen atoms mayoriginate from the sulfonate or carboxylate groups. For ionomers withperfluorinated backbones, some of the oxygen atoms may be ascribed to watercoordination as well. In fully hydrated zinc neutralized ionomers, thezinc cation exists as Zn( H2O)62+. In contrast, the fully hydrated monovalentrubidium neutralized ionomers exhibited a highly disordered environmentabout the cation.
Raman Scattering and Photoluminescence of Pristine and Ion Implanted Langmuir-Blodgett Polydiacetylene Thin Films
Authors: Kaneko F. , Dresselhaus M. S. , Braunstein G. , Kouno T. , Liu Y. , Shibata M. , SAito K. , Kobayashi S. 
Published: March 2011

AbstractFundamental optical properties of Langmuir-Blodgett polydiacetylene (LB PDA) ultra thin films are investigated. The LB films exhibit a strong absorption peak at about 16000 cm-1 and a weak and broad peak at about 17500 cm-1; the color of the film is blue. After annealing at 90°C, a blue shift of the absorption peaks is observed; that is, the color of the LB films changes from blue to red. The phase transition corresponding to the color change is studied using Raman spectroscopy as a function of annealing temperature. For annealing temperatures between 50 and 60°C, the results show significant change in the ratio of Raman line intensities due to C≡C and C=C stretch modes. Such a transition is also observed for laser annealed LB PDA films. Furthermore, the photoluminescence (PL) properties of pristine (blue), annealed (red) and ion implanted (red) LB PDA films are investigated. The photoluminescence of both pristine and annealed LB PDA films show sharp peaks at about 15500 cm-1. The annealed LB PDA films have an additional small peak or shoulder at about 18000 cm-1. The photoluminescence peaks of red films implanted with 200keV As+ ions are observed at about 16000 cm-1 and become broad with increasing ion implantation dose in the range 1012–1015 cm-2.
Studies of Molecular Orientation in Deformed Semicrystalline Polymers by X- Ray Scattering Employing Synchrotron Radiation
Authors: Röber S. , Gehrke R. , Zachmann H. G. 
Published: March 2011

IntroductionThe possibility of using synchrotron radiation as a source of X-rays for scattering experiments has considerably improved the methods of the characterisation of the molecular orientation and molecular order in polymers. In another publication [1], it has been shown that the morphology of ultra highly drawn polyethylene is correlated to the kinetics of isothermal melting, as determined by X- ray scattering employing synchrotron radiation. In this paper we present some results on chain orientation and orientation of crystal lamellae surfaces in uniaxially and biaxially drawn films of polyethyleneterephthalate (PET). These results were obtained by inserting a pole figure goniometer into the synchrotron radiation beam and measuring the wide angle X-ray scattering (WAXS) and small angle X- ray scattering (SAXS) with different angles of incidence of the primary beam onto the sample.
Polymer Chain Deformation in Stretched and Swollen Elastomers
Authors: Ullman Robert 
Published: March 2011

AbstractIn the early theories of rubber elasticity, the retractive force and change in free energy of a stretched specimen were calculated from the deformation of the polymer chains of which the rubber network was formed. The mean chain deformation was presumed to be the same as that of the macroscopic specimen, an assumption which seemed reasonable, but could not be confirmed experimentally. Small angle neutron scattering (SANS) made measurement of chain dimensions possible, and it was soon discovered [1], [2] that the actual relation between dimensional changes of the polymer chain and deformation of the specimen was not at all what had been assumed.SANS studies of carefully prepared elastomeric networks provide the most direct experimental information required for a molecular theory of rubber elasticity, and have stimulated many new developments.
A Deformation-Induced Phase Separation in the Solid State
Authors: Lefebvre J. M. , Porter R. S. , Wignall G. D. 
Published: March 2011

AbstractAmorphous Polymethylmethacrylate/Polyethyleneoxide blends deformed by solid-state coextrusion exhibit anomalous anisotropic Small Angle Neutron scattering patterns in the low q range. It is shown that upon drawing the samples have undergone phase separation to some extent. The resulting structure of the system is characterized by combining scattering techniques with Differential Scanning Calorimetry.
A Double-Tilt Small Angle Neutron Scattering Experiment on Deformed Poly Mer Systems
Authors: Saraf R. F. , Lefebvre J. M. , Porter R. S. , Wignall G. D. 
Published: March 2011

AbstractA double rotation goniometer has been mounted in the neutron beam in order to characterize the molecular deformation in polymers subjected to various strain conditions.The results provide a direct verification of the fiber symmetry in solid state coextruded polymethylmethacrylate (PMMA) and polypropylene (PP) homopolymers.In the case of the shear banding phenomenon, we have been able to test the validity of the simple shear assumption: it also provides a direct estimate of the finite shear strain involved in the process. As a last illustration ofthe method, we also consider the biaxial deformation of PP and PMMA squeezed under various temperature and strain-rate conditions.
Time-Resolved Saxs and Waxs Studies on Ordering Process in Oriented Crystallization of Polymers
Authors: Saijo Kenji , Hashimoto Takeji 
Published: March 2011

AbstractMechanism and dynamics of the ordering process in oriented crystallization of polymers were investigated by time-resolved small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXS). As a model system for the oriented crystallization, a cross-linked polybutadiene rubber with a high cis-1,4-linkage was chosen, and the structure evolution during the isothermal crystallization was investigated under constant elongations by real time and in situ analyses of the microscopic observables such as long spacing, crystallite size, SAXS integrated intensity, WAXS crystallinity and WAXS line width as well as a macroscopic observable such as stress. The isothermal ordering processes were explored in three different crystallization regimes: crystallization from (i) unoriented melts, (ii) weakly-to-moderately oriented melts and (iii) highly oriented melts.
Small Angle X-Ray Scattering Studies of Fatigue in Polystyrene
Authors: Brown H. R. , Kramer E. J. , Bubeck R. A. 
Published: March 2011

AbstractSmall angle scattering has been used to study the mechanical fatigue of crazes in polystyrene. The high radiation intensity obtainable from a synchrotron has permitted the examination of the processes that occur during the fatigue in real time. Both the short term changes that occur within a single cycle and the long term changes that occur over many cycles have been observed.Most of the craze growth, as measured by the scattering invariant obtained at peak deformation, occurred in the first cycle of fatigue. However the craze fibril diameter, obtained by Porod analysis, doubled over 250 cycles. As the volume of craze was not growing during during the fatigue this fibril diameter increase was believed to occur by change, that is coalescence, of the preexisting fibrils.The SAXS patterns obtained at a number of different deformations within a single cycle were compared with calculated patterns obtained assuming that the fibrils bend in a sinusoidal manner. Good qualitative agreement was obtained so it was concluded that the craze fibrils showed considerable deformation as the craze was unloaded and then straightened out again on reloading. When the ratio of minimum to maximum deformation was decreased from 0.9 to 0.5 the fibril deformation (contraction) increased to 10% with the fibrils remaining straight. As the minimum deformation was decreased below this the craze stress tends to zero and fibril buckling was evident. The main changes in fatigue lifetime occurred over the regions where there fibrils were straight, perhaps because buckling involves relatively small deformations.
Optical Interferometry on Crazes in Solvent Vapours at Very Low Pressure in Polymethylmethacrylate.
Authors: Schirrer R. , Galleron G. 
Published: March 2011

AbstractThe fracture toughness and the craze shape of a propagating single crack/craze in polymethylmethacrylate has been measured in a very low pressure toluene gas environment by means of optical interferometry. Below a velocity of 0.01 mm/s the craze size increases up to 4 times the craze size in air, whereas the fracture toughness remains identical to the toughness in air. Above 0.01 mm/s the crack/craze behaves like a crack/craze in air.
The Coupling Model: A Fundamental Mechanism Governing Time Dependent Properties of Relaxations, Structural Recovery and Nonlinear Viscoelasticity
Authors: Rendell R. W. , Ngai K. L. , Yee A. F. 
Published: March 2011

AbstractThe recent renewal of interest in the time dependent response of complex material systems stems both from their increasing importance and from recent advances in theoretical tools and concepts. This paper describes one of these advances, the coupling model of relaxation. The coupling model proposes a view of how relaxation proceeds in time in which a primitive relaxation mode is coupled to its complex surroundings. Examples of the coupling model predictions for terminal relaxations, primary-segmental relaxations including physical aging, and secondary relaxations in polymers are described. It is able to confront and quantitatively explain several long-standing problems and anomalies for which traditional approaches, in their present form, such as distributions of relaxation times, free volume, configuration entropy and reptation are not successful. The coupling model response function is also appropriate for structural nonequilibrium and its predictions for volume recovery are described. The same coupling model response function is used as a timedependent kernal in a constitutive equation to discuss nonlinear viscoelasticity. The model incorporates the strain history dependence and allows for the evolution of material structure. Using information from strain-tickle experiments on polycarbonate and polyetherimide, we show that the coupling model reproduces the essential features observed experimentally for a variety of strain histories.