bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical Behavior of Benzocyclobutene Films on Silicon Substrates
Authors: Townsend P. H. , Stokich T. M. , Huber B. S. 
Published: March 2011

AbstractThe evolution of the stress in coatings derived from divinylsiloxane bisbenzocyclobutene, mixed stereo and positional isomers of 1,3-bis(2-bicyclo[4.2.0]octa-1,3,5-trien-3-ylethenyl)-1,1,3,3-tetramethyl disiloxane (CAS 117732-87-3), has been measured on silicon substrates with an optically levered beam during thermal cycles. The stress at room temperature in gelled coatings varies between ca. 15 MPa and 45 MPa depending on the cure schedule. The progression of the polymer's glass transition temperature is correlated with the evolution of the structural state observed with FTIR. A method is presented for predictably controlling substrate curvature during multilayer processing.
Microhardness of Thin SIO2 Films On Silicon.
Authors: Yost B. , Li Che-Yu , Bergman-Reuter Bette , Sullivan Tim 
Published: March 2011

AbstractHardness properties of CVD SiO2, films deposited on silicon substrates are investigated by microindentation techniques. It is found that the hardness of these films is sensitive to the thermal histories and doping and is less influenced by the residual stress levels.
Preparation of TI-Ba-Ca-Cu Superconducting Oxide Films by Spray Pyrolysis Technique
Authors: Koo H.S. , Kuo T.L. , Kuo D.H. , Lin R.J. , Lee W.H. , Wu P.T. 
Published: March 2011

AbstractSuperconducting TI-Ba-Ca-Cu-O(TBCCO) films with zero resistance temperatures above 100K have been prepared on (001)MgO single-crystal substrates by the combination techniques of spray pyrolysis and Tl-diffusion. The as-sprayed Ba-Ca-Cu-O films and the sintered TBCCO superconducting bulks were wrapped in Au foil and heated in oxygen at temperatures ranging from 890 to 920°C and cooled to room temperature by furnace cooling. Highly c-axis oriented superconducting films were obtained and their average thicknesses were about 5-10 μm. The characteristics of TBCCO films by X-ray diffraction, scanning electron microscopy and electrical property are discussed.
Stress and Resistivity in Reactively Sputtered Amorphous Metallic Ta-Si-N Films
Authors: Kwok C.-K. , Kolawa E. , Nicolet M-A. , Lee Ray C. 
Published: March 2011

AbstractWe have measured the stress and the electrical resistivity of Ta-Si-N films deposited in an rf magnetron system by reactive sputtering of Ta5 Si3 target in an Ar-N2 mixture. The stress was determined by measuring the curvature of thin Si substrates with a stylus instrument. The atomic composition was established from backscattering spectra. The resistivity was derived from four-point probe measurements. The stress, the resistivity, and the atomic composition were studied as a function of various processing parameters (total pressure, gas composition). The stress is always compressive and can be changed from 0.38 - 1.48 GPa by such means. The resistivity is principally a function of the nitrogen composition and rises as the nitrogen amount increases. The results are compared with those reported for other amorphous metallic alloys.
Strains and Relaxations Near metal Alumlnide/Semiconductor Interfaces
Authors: Gerberich W.W. , Angelo J.E. , Keller R.R. , Wowchak A.M. , Cohen P.I. 
Published: March 2011

AbstractMechanisms and phenomena of strain relaxation at bi-material interfaces have been studied for over half a century. The details, however, and limiting kinetics, thermodynamics and mechanics are still being sorted out - particularly for large misfit systems. Three techniques are required to accurately portray strain distributions during and after epitaxial growth: RHEED, TEM and SACP. Reflection high energy electron diffraction (RHEED) is used to measure the lattice parameter during growth. Both transmission electron microscopy (TEM) and selected area electron channeling pattern (SACP) analysis are necessary to identify the defects and the strain distribution. These techniques have been applied to NiAl and FeAl grown by MBE on GaAs with a thin AlAs buffer layer. It is shown that both island and layer by layer growth can occur with the corresponding defects being remarkably similar in character. From a combined Moiré, HREM and computer simulation, the dislocation character is assessed. Both <100> dislocations from half-loops or island edges may occur providing only partial relaxation of the film-substrate systems. The impact of the remaining elastic strain distribution on kinetic measurements of dislocation velocities is discussed.
Spiral Cracking Around a Strained Cylindrical Inclusion in a Brittle Material and Implications for Vias in Integrated Circuits
Authors: Freund L. B. , Kim K. S. 
Published: March 2011

AbstractThe practice of forming electrical conduction paths in an insulating material by filling cylindrical holes with molten metal can result in high residual stresses when the metal cools. Residual stress is greatest near the metal-insulator interface, and stress relaxation by means of de-adhesion is possible. Another failure mode that poses greater practical difficulties is the growth of cracks along paths which spiral away from the interface into the brittle material. Such cracks may occur singly or in pairs, and their lengths can be sufficiently great to provide links with adjacent conduction paths. Such cracks are considered from the fracture mechanics point of view. The residual stress field is relaxed by the growth of spiral cracks which are modeled as continuous distributions of dislocations. It is assumed that these cracks grow so that the stress state on the prospective fracture plane just ahead of the crack tip is purely tensile. The paths are determined by means of an incremental numerical procedure.
Aging and Fracture Behavior of Polymers
Authors: Chudnovsky A. , Bosnyak C.P. 
Published: March 2011

AbstractSignificant changes in polymer materials and their subsequent mechanical performance can occur within an expected engineering service time. These changes can be further exacerbated with environmental effects such as with solvents and mechanical stresses. Examples are given of premature field failures which illustrate the inadequacy of existing understanding and design criteria. A new approach is outlined which is based on the coupling of two fundamental concepts; a geometrical representation of material morphology on various scales and thermodynamics of morphological transformation. These concepts allow one to bridge an existing understanding of aging on molecular and morphological levels with a phenomenological continuum mechanics approach.
Curvature Measurements of Tri-Material Structures Under Thermal Excursion
Authors: Lu Guo-Quan , Mogilevsky Boris , Gupta Tapan K. 
Published: March 2011

AbstractThe bending curvatures of tri-material plates have been measured using in situ laser reflection technique at temperatures ranging from 20°C to 160°C. The tri-material structures are formed by attaching silicon wafers to ceramic substrates with die-attach adhesives from solder-like (elastic modulus ≈ 24 GPa) to gel-like (elastic modulus ≈ 0.003 GPa) characteristics. The temperature dependence of curvature as a result of the thermal expansion mismatch is measured. The structure bonded by the gel-like adhesive has substantially lower, about a factor of ten less, bending than the structures attached by the other two types of adhesives. We found good agreements between the measurements and the theoretical derivations by Suhir[1] for the bending curvature of finite tri-material assembly.
Residual Stress Measurement in Silicon Substrate After Local Thermal Oxidation Using Microscopic Raman Spectroscopy
Authors: Miura Hideo , Sakata Hiroshi , Merl Shinji Sakata 
Published: March 2011

AbstractThe residual stress in silicon substrates after local thermal oxidation is discussed experimentally using microscopic Raman spectroscopy. The stress distribution in the silicon substrate is determined by three main factors: volume expansion of newly grown silicon–dioxide, deflection of the silicon–nitride film used as an oxidation barrier, and mismatch in thermal expansion coefficients between silicon and silicon dioxide.Tensile stress increases with the increase of oxide film thickness near the surface of the silicon substrate under the oxide film without nitride film on it. The tensile stress is sometimes more than 100 MPa. On the other hand, a complicated stress change is observed near the surface of the silicon substrate under the nitride film. The tensile stress increases initially, as it does in the area without nitride film on it. However, it decreases with the increase of oxide film thickness, then the compressive stress increases in the area up to 170 MPa. This stress change is explained by considering the drastic structural change of the oxide film under the nitride film edge during oxidation.
Effects of Plastic Deformation on Charge Transport in Mercuric Iodide Radiation Detectors
Authors: Marschall J. , Milstein F. , Georgeson G. , Gerrish V. 
Published: March 2011

AbstractThe effects of bulk plastic deformation of mercuric iodide (HgI2), upon electronic properties which are relevant to the performance of HgI2 as a radiation detector, were examined experimentally. Hole lifetimes, as well as hole and electron mobilities, were measured at various stages of sample deformation. Hole lifetimes decreased by a factor of 2 under strains of several percent; carrier mobilities did not change significantly, except during creep loading where electron and hole mobilities decreased by about 65% and 25%, respectively. Additionally, dark current measurements were made on specimens with varying degrees of accumulated plastic strain; dark current values did not strongly reflect the extent of plastic damage in deformed specimens.
Creep-Fatigue Behavior of Microelectronic Solder Joints
Authors: Ross R.G. , Wen L.C. , Mon G.R. , Jetter E. , Winslow J. 
Published: March 2011

AbstractEven at room temperature, solder joints exhibit both creep and fatigue behavior that is strongly dependent on solder joint configuration, the thermal environment, and the solder alloy properties. The microstructures of solder joints with up to 25 years of aging have been studied using SEM/EDS and metallographic techniques. Data are presented on grain growth and metallurgical composition versus aging time. A special non-linear finite element creep-fatigue simulation model has been developed, based on measured strain-rate hardness relationships, and used to analytically predict the effects of observed metallurgical changes and the effects of lead stiffness in solder joint creepfatigue interaction. To corroborate the analytical results, a special bi-metallic test fixture has been developed to accelerate the thermo-mechanical loading of solder joints in thermal cycling environments. Measured time-to-failure data for various electronicpackage lead configurations/stiffnesses, including gullwing and J-lead, are presented and shown to be in reasonable agreement with the analytical results.
Finite Element Simulation of Hillock Formation in Aluminum Interconnect
Authors: Burrell L. G. , Kapur S. , Shareef I. 
Published: March 2011

AbstractA non-linear finite element model has been used to simulate hillock formation in an aluminum interconnect structure. The hillock formation is caused by the thermal expansion mismatch between aluminum and the surrounding SiO2 passivation. Using the ABAQUS software [1], a large strain elastic-plastic-creep analysis was done. The results showed there were stresses large enough to cause yield and permanent deformation of the aluminum interconnect.
A Methodology for Reliability Assessment of Non-Ductile Encapsulants
Authors: Wong Boon , Sandkulla David C. 
Published: March 2011

AbstractThis paper presents a probabilistic fracture-mechanics based methodology for the reliability assessment of non-ductile encapsulants. The study used an alumina-epoxy encapsulant as a working example and assessed the reliability in terms of (1) fast fracture and (2) delayed failure behavior of the material.Applying the Weibull probabilistic model to flexural strength data, survival probabilities and strength requirements against fast fracture of the encapsulant under various stress states were quantified. Unifying the probabilistic concept and linear elastic fracture mechanics (LEFM), the probabilistic lifetime of the encapsulant was predicted as a function of stress magnitude, stress state, and material size. Merging the results obtained from this study with the mechanical response results independently acquired from finite element analysis (FEA) one may then establish conservative design margins for the encapsulant used in various electronic assemblies.
Effect Of Moisture On The Physical Properties Of Polyimide Films
Authors: Subramanian Rajeevi , Pottiger Michael T. , Morris Jacqueline H. , Curilla Joseph P. 
Published: March 2011

ABSTRACTMoisture absorption and its effect on electrical properties were measured for several polyimides. A Quartz Crystal Microbalance (QCM) was used to investigate the moisture absorption in BPDA/PPD, PMDA/ODA, and BTDA//ODA/MPD polyimides. The steady-state moisture uptake in polyimides as a function of relative humidity (RH) was determined by exposing film samples to successively higher RH values ranging from 10 to 85% at 25°C. The isothermal moisture absorption as a function of percent RH was found to be nearly linear for all of the polyimides studied. The effect of moisture on the electrical properties of a BPDA/PPD polyimide was also investigated. The relative dielectric constant at 25 °C was found to be a linear function of the moisture absorbed.
Stress measurement Of BPDA/PDA Polyimides From Poly(Amic Acid) And Photosensitive Polyimide Precursors On Silicon
Authors: Nomura Hideshi , Eguchi Masuichi , Niwa Katsuhiro , Asano Masaya 
Published: March 2011

ABSTRACTThe intrazeolite chemistry of the two germylene complexes Cl2(THF)GeM(CO)5(M = Mo, W) was studied with x-ray absorption spectroscopy (Ge, Mo, W edge EXAFS) and in-situ FTIR/TPD-MS techniques. The slightly decarbonylated GeMo complex interacts with the framework of NaY zeolite at room temperature and retains the Ge-Mo bond up to about 100° C. In proton-loaded HY zeolite, framework interactions increase at elevated temperature, and the attached complex retains the Ge-Mo bond up to about 120° C. The Ge-Mo bond is cleaved at higher temperatures. MoC1x and Mo-Mo species are formed in NaY and HY zeolite, respectively, while GeClx fragments are anchored to the zeolite framework.The complex Cl2 (THF)GeW(CO) 5 retains all five CO ligands up to about 100° C in both NaY and the proton form. Detectable anchoring occurs at room temperature in NaY and at about 80° C in the proton form. WC1x species are formed upon cleavage of the Ge-W bond at higher temperatures.
Thermal Expansion And Viscoelastic Properties Of A Semi-Rigid Polyimide
Authors: Smith Thor L. , Kim Churl S. 
Published: March 2011

ABSTRACTStudies were made of the physical properties of the commercially available polyimide Upilex-SGA, which is prepared from biphenyl dianhydride and p-phenylene diamine. Annealing the Upilex-SGA for 2 hr Linder N2 at 400°C gave a film that expanded continuously when heated at a fixed rate, in contrast to the as-received film. The linear expansion showed a change of slope at 84°C and also at 295°C, the later being Tg. The thermal coefficient of linear expansion at all temperatures was very small, even above 295°C it is 27.8 × 10−6. Its stress-strain curve did not exhibit a yield point, even though its ultimate elongation is ˜23%. Similar behavior is shown by the PMDA-ODA polyimide, except its ultimate elongation is ˜70%,. The unusual stress- strain curves exhibited by these polyimides is undoubtedly caused by their liquid-crystalline morphology. The stress-relaxation modulus was measured at 0.5% extension and 12 temperatures from 30 to 330°C. Derived isochrones showed that the 1-s tensile modulus at 20°C is 9.0 GPa, but at 330°C it is 2.0 GPa. Creep curves were also measured at a stress of 30 MPa and at 10 temperatures from 30 to 340° C. Master curves prepared from the relaxation and creep data are discussed briefly and evidence is given which, show that the superposition method is not truly valid for this polyimide, which actually is not surprising.
Polyimide Considerations In Thin-Film Electronic Packaging
Authors: Pawlowski W. P. 
Published: March 2011

ABSTRACTFree-standing polyimide film is used extensively in tape automated bonding (TAB) and flexible printed circuit (Flex) applications because of its excellent chemical, mechanical, and electrical properties. Kapton polyimide film has been the material of choice for many years. Recently, a new polyimide film, Upilex, has been introduced into the marketplace. The primary property differences between Kapton and Upilex result from differences in the chemical composition of each film. A review of property/product performance indicates that Upilex S is preferred with respect to dimensional stability, metal/polyimide and adhesive/polyimide adhesion, chemical inertness and glass transition temperature.
Liquid Crystalline Thermosets As Materials For Microelectronics
Authors: Ober C. K , Barclay G. G. 
Published: March 2011

ABSTRACTNew liquid crystalline thermosets have been prepared from end-functional monomers and oligomers of varying molecular weight. Both triazine and epoxy networks were explored. Of primary interest was the exploitation of the mesophase properties of these networks for developing polymers with high thermal stability and low coefficients of thermal expansion (CTE). Curing was carried out either within the nematic mesophase or the isotropic phase of the prepolymers. Transition temperatures associated with the mesophase were observed to change after curing under these two sets of conditions. The networks with the highest crosslink density were found to exhibit the lowest CTE values. Crosslinking of these thermosets was also carried out in the presence of a 13.5 Tesla magnetic field to determine the effect of orienting fields on the curing of the LC network. Orientation parameters as measured by wide angle x-ray diffraction were as high as 0.6. Values of the coefficient of thermal expansion as low as 15 ppm were achieved in the aligned direction. Of the two resin types, those with the triazine crosslinks had the lowest thermal expansion coefficient. Other thermal properties of these networks will be discussed.
Phase Transitions In Blends Of Liquid Crystalline Polymer/Polyether Imide
Authors: Nam Joonhyun , Fukai Tomohiro , Kyu Thein 
Published: March 2011

ABSTRACTA thermotropic liquid crystalline copolymer consisting of bisphenol E diacetate, isophthalic acid and 2,6-naphthalene dicarboxylic acid was blended with polyether imide by dissolving in a mixed solvent of phenol/1,1,2,2-tetrachloroethane in a ratio of 60/40 w/w and co-precipitating the ternary solution in non-solvent (methanol). Wide-angle x-ray diffraction and differential scanning calorimetry studies revealed that the blends were completely amorphous with a single glass transition temperature. The single phase was probably entrapped during solvent removal, but these mixes were unstable and phase separated upon heating. Mesophase structure developed in the LCP rich region with continued annealing. The evolution of crystalline texture was monitored by time-resolved wide-angle x-ray diffraction following a temperature jump from ambient to 265 °C. The recrystallization process of LCP was found to slow down in the blend state relative to that of the neat LCP.
Surface Properties Of Photoablated Thermostable Polymers
Authors: Hiraoka Hiroyuki , Lazare Sylvain , Cros Alain , Gustiniani R. 
Published: March 2011

ABSTRACTSurface properties of photoablated thermostable polymers are considerably different from those of original, unexposed ones, and of mercury UV lamp exposed surfaces. They also depend on the laser exposure conditions. This paper reports such non-linear phenomena observed on polymer surfaces, caused by excimer laser exposures, like increased hydrophilicity of polymer surfaces, imagewise wetting and metallizations, and new metal compound formations on laser exposed polymer films. Because these features are limited to polymer films with high glass transition temperature, like polyimides and poly(phenylquinoxaline), photo-mechanical effects may be important. In some cases, new interfacial reactions appear between exposed polymer surfaces and deposited metal films. Swelling of polyimide in pre-photoablation irradiation is discussed.
A Calorimetric Evaluation Of The Peel Adhesion Test
Authors: Goldfarb J. L. , Farris R. J. , Chai Z. , Karasz F. E. 
Published: March 2011

ABSTRACTSimultaneous mechanical and calorimetric measurements of the work and the heat of peeling have been made for polyester films bonded to rigid metal substrates with a pressure sensitive adhesive. Most of the work expended in peeling is consumed by plastic deformation and viscous dissipation. 70% to 85% of the peel energy is dissipated as heat. The peeled polyester films were tightly curled. Energy stored in the peeled polyester films was measured using solution calorimetry and a significant fraction of the peel energy not dissipated as heat was found to be stored in the peeled films.
A Novel Photochemical Route For Modifying Surfaces: Prospects And Applications.
Authors: Harmer Mark A. 
Published: March 2011

ABSTRACTPotential applications of a very general route to photochemically modifying a range of surfaces will be described. Surfaces which have been modified vary considerably and include polyimide, polyethylene, fluoropolymers, polyester, glass, tin oxide and aluminum. Photoactivated azides, for example 3-azidopyridine, have been found to be very effective at modifying a range of surfaces. Using this method organic type functional groups, in this case pyridine type groups, can be photografted on to the surface. As a result of photomodification the surface properties change. In the case of polyethylene for example the surface becomes more hyrophilic and shows improved adhesion to metals. These modified surfaces also display acid-base character. In the protonated form anions can be exchanged into the film. This method has been used to modify a metal oxide electrode surface to develop chemically modified electrodes. The process may also be used in lithography.
Control Of Polyimide Surface Property By Changing The Surface Morphology
Authors: Lee Kang-Wook 
Published: March 2011

ABSTRACTThe surface properties of polyimide can be changed without altering the bulk properties. The surface layer (around 200 Å) of fully cured PMDA-ODA polyimide is chemically modified to polyamic acid which is subsequently imidized at 230 °C for 30 min to give an unordered polyimide surface. This unordered layer seems amorphous since it swells well in NMP. The modified surfaces are analyzed by surface sensitive techniques such as contact angle measurement, XPS, ISS, and external reflectance infrared (ERIR) spectroscopy. Adhesion of polyimides and chromium on the amorphous polyimides is greatly enhanced. Interdiffusion and subsequent mechanical interlocking are the major contributions to the polyimide-polyimide adhesion.
Fluorinated Polyimide Block Copolymers
Authors: Labadic J. W. , Sanchcz M. I. , Cheng Y. Y. , Hedrick James L. 
Published: March 2011

ABSTRACTBlock copolymers based on the poly(amic ester) of poly(4,4′-oxydiphenylene-pyromellitide) and perfluoroalkylene aryl ethers were synthesized from preformed amine terminated perfluoroalkylene aryl ether oligomers. Fluoropolymer structure, wt% incorporation, and molecular weight were varied. Reduction in the dielectric constant to 2.8–2.9 and reduced moisture sensitivity were observed for block copolymers with 55 wt.% poly(perfluoroalkylene aryl ether) content without significant compromise of mechanical or thermal properties.