bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of a Decomposed Analysis Procedure for Area-Array Packages
Authors: Thompson Terrace B. , Subbarayan Ganesh
Published: July 2002

The goals of the present paper are to apply the recently developed decomposed analysis procedure using a computer code developed in this study. The decomposed technique enables one to determine the equilibrium configuration of electronic packages with significant computational efficiency at a reasonable accuracy. Further, it allows the independent analysis of the subsystems enabling “reusable” modules in a manner analogous to the object-oriented programming paradigm of modern computer languages. The code described here uses a nonlinear optimization procedure that ensures the approximate satisfaction of the balance of mechanical energy. The developed procedure is demonstrated on a variety of two- and three-dimensional hypothetical and “real-world” electronic packages. It is shown that with the use of the decomposed solution methodology, for a 225 I/O PBGA package, a speedup of nearly seven times is achieved at an accuracy loss in displacements of approximately 5.5 percent. It is also shown that the calculated peak shear displacements agree very well with experimental measurements made using laser moire´ interferometry. Since the analysis procedure is independent of the number of solder interconnects, significantly larger time savings are expected for larger packages.
An Optical Method for Measuring the Two-Dimensional Surface Curvatures of Electronic Packages During Thermal Cycling
Authors: Du Yong , Zhao Jie-Hua , Ho Paul
Published: July 2002

An optical method was developed to measure the two-dimensional (2D) surface curvatures of electronic packages by employing four laser beams. Each laser beam measures the slopes of the surface at the incident point along two perpendicular directions. By combining four pairs of slopes, the 2D surface curvatures of the package can be calculated. The surface warpage of an underfilled flip-chip package during thermal cycling was measured by this method and the result was verified by finite element analysis (FEA). Both experimental and FEA results show that the surface warpage is almost a linear function of temperature between 25°C and 150°C for the measured package.
Incandescence Measurement During CO2 Laser Texturing of Silicate Glass
Authors: Li Lei , Bennett Ted D.
Published: July 2002

Laser zone texture is a new approach to improve tribology performance of high aerial density disks made with glass substrates. In this process, nanotexture is introduced to the surface by discrete laser pulses. The topography change is due to the elevation of fictive temperature in the short time and high temperature scales that occur through the laser energy coupling with glass. To exercise better control over this thermal process, knowing the temperature field induced by the laser pulse and the timescale of the thermal cycle are very important. In this paper, emission measurements are made from a laser-heated surface of approximately 300 μm2 and temporally resolved to 100 ns. Several emission bands are collected in the visible. From emission data, the extensive heat capacity of the heat affected zone is derived, allowing peak surface temperatures to be determined from the pulse energy. Experimental results are compared with a numerical model to determine the validity of earlier calculations and conclusions.
Heat Transfer and Pressure Drop Characteristics During R22 Evaporation in an Oval Microfin Tube
Authors: Kim Man-Hoe , Shin Jeong-Seob , Bullard Clark W.
Published: July 2002

An experimental study on R22 evaporating heat transfer in round and oval microfin tubes has been performed. The oval tube was an elliptic tube of axis ratio 1:1.5, which was fabricated from the round tube with an outer diameter of 9.52 mm and 18 deg helix angle counterclockwise. The test section was a straight horizontal tube of 0.6 m in length and was heated electrically by a tape heater wound on the tube surface. Heat flux of 12 kW/m2 was maintained constant and the range of refrigerant quality was 0.2–0.8. The tests were conducted for evaporation at 15 °C for 30–60 kg/h mass flow rate (mass flux based on the oval tube: 150–300 kg/m2s) and the installation angles of the oval tube were varied between 0 and 135 deg in the circumferential direction. The local and average heat transfer and pressure drop characteristics for the oval tube were compared to those for the baseline round tube. The average two-phase heat transfer coefficients for the oval tube were 2–12 percent higher than that for the round tube and pressure drops for both tubes are similar. The single heat transfer coefficient and friction factor correlations for the round and oval microfin tubes are developed within the rms errors of ±5.6 percent and ±10.0 percent, respectively.
Thermal Deformation of Initially Curved Substrates Coated by Thin Inhomogeneous Layers
Authors: Wikstro¨m A. , Gudmundson P.
Published: July 2002

Thermal curvature changes and membrane strains are analyzed for elastic shallow shell substrates which are coated by thin, generally inelastic, inhomogeneous and anisotropic layers. The analysis is restricted to linear kinematics. It is shown that the deformation is governed by the corresponding solution for a flat substrate and a correction due to the initial curvature. The correction is determined from a shallow shell problem for the bare substrate with a loading expressed by the coefficients of thermal curvature for the substrate/layer system. For constant initial curvatures, certain analytic solutions are presented. For situations when the initial deflection of the substrate is much larger than the substrate thickness, a boundary layer solution is derived. In the particular case of a circular isotropic substrate with a spherical initial curvature and a coating of arbitrary anisotropy, the solution is presented in closed form. For nonflat substrates, measured curvatures can generally not be used to extract layer stresses without a proper compensation for the initial curvature. In the paper, it is explicitly presented how to accurately compensate for a spherical initial curvature. The results are particularly discussed in relation to curvature measurements on Silicon substrates.
Effect of Curved Bar Properties on Bending of Curved Pipes
Authors: Cherniy V. P.
Published: July 2002

A general solution is presented for in-plane bending of a thin-walled short-radius curved pipe. The problem is solved considering the properties of a curved bar—an actual radius of curvature of longitudinal fibers and the neutral line displacement. The theory is developed using minimization of the total energy. The relationships of the theory of elastic thin shells are used. The obtained results for the strains and stresses in curved short-radius pipe bends are compared with published theoretical and experimental data. The properties of a curved bar being taken into account enable to correct seriously the distribution and peak values of the strains which take place in curved pipes of large curvature subjected to bending.
Learning-Based Preference Modeling in Engineering Design Decision-Making
Authors: Wan Jie , Krishnamurty Sundar
Published: July 2002

Focusing on the efforts towards a consistent preference representation in decision based engineering design, this paper presents a learning-based comparison and preference modeling process. Through effective integration of a deductive reasoning-based on designer’s outcome ranking in a lottery questions-based elicitation process, this work offers a reliable framework for formulating utility functions that reflect designer’s priorities accurately and consistently. It is expected that this integrated approach will reduce designer’s cognitive burden, and lead to accurate and consistent preference representation. Salient features of this approach include a linear programming based dynamic preference learning method and a logical analysis of preference inconsistencies. The development of this method and its utilization in engineering design are presented in the context of a mechanism design problem and the results are discussed.
Radiation Heat Transfer Between Fluidizing Particles and a Heat Transfer Surface in a Fluidized Bed
Authors: Yamada Jun , Kurosaki Yasuo , Nagai Takanori
Published: July 2002

We have investigated the radiation heat transfer occurring in a gas-solid fluidized bed between fluidizing particles and a cooled heat transfer surface. Experimental results reveal that cooled fluidizing particles exist near the surface and suppress the radiation heat transfer between the surface and the higher temperature particles in the depth of the bed. The results also clarify the effects of fluidizing velocity, optical characteristics of particles, and particle diameter on the radiation heat transfer. Based on these results, the authors propose a model for predicting the radiation heat transfer between fluidizing particles and a heat transfer surface.
A Special Type of Crank Mechanism With Variable Stroke
Authors: Mimmi Giovanni , Pennacchi Paolo
Published: July 2002

The aim of this paper is a detailed analysis of a particular mechanism with variable piston stroke. This crank mechanism is presently applied to metering pumps, because it allows the piston stroke to be adjusted in length and permits the pump flow to be changed also during the pump functioning. The following analysis shows the different characteristics of piston motions obtainable by changing the ratios among the mechanism rod lengths.
Gear Parameters for Specified Deflections
Authors: Dooner David B. , Santana Roberto A.
Published: July 2002

The geometry of a gear pair depends on the center distance and the included angle between the two axes of rotation along with the axial positions of the toe and heel (face width). During operation, loads can cause the gear system components to deflect such that the relative position and orientation between the gear elements change. This paper illustrates how certain gear body displacements are used to specify a gear pair’s geometric parameters that can improve contact during mesh. An illustrative example involving cylindrical gear elements is presented to demonstrate the procedure.
An Exit Burr Model for Drilling of Metals
Authors: Saunders L. Ken Lauderbaugh , Mauch Craig A.
Published: July 2002

The mechanics of the formation of exit burrs for drilling metals are analyzed. A burr formation model is developed where the material in front of the drill is modeled as an axi-symmetric, circular plate of varying thickness. The drilling thrust forces are distributed as a pressure along the top surface of this plate. The stress state is then calculated. Material removal continues until a failure condition is reached. At the point of failure of the plate the remaining material is bent out to form the burr. The model also includes temperature effects. Experimental verification was conducted on 2024-T351 aluminum and on 7075-T561 aluminum. Two types of drill geometry were considered. The experiments were conducted with feeds from 0.05 to 0.35 mm/rev. The model accurately predicts the experimental data.
On the Calculation of Length Scales for Turbulent Heat Transfer Correlation
Authors: Barrett Michael J. , Hollingsworth D. Keith
Published: July 2002

Turbulence length scale calculation methods were critically reviewed for their usefulness in boundary layer heat transfer correlations. Using the variance of the streamwise velocity and the dissipation spectrum, a rigorous method for calculating an energy-based integral scale was introduced. A principal advantage of the new method is the capability to calculate length scales in a low-Reynolds-number turbulent boundary layer. The method was validated with data from grid-generated, free-shear-layer, and wall-bounded turbulence. Length scales were calculated in turbulent boundary layers with momentum thickness Reynolds numbers from 400 to 2100 and in flows with turbulent Reynolds numbers as low as 90.
Dynamic Behavior of Twin-Piece Vane Machine
Authors: Guoyuan Ma , Qisen Yan , Yongzhang Yu
Published: July 2002

This paper describes a twin-piece vane machine which has freely movable double vanes assembled in each slot machined in the rotor providing double seal lines between the vane tips and the inner surface of the cylinder. Analysis of the motion, forces, friction, wear and stresses in the vanes with a dynamic model demonstrates that the twin-piece vane machine has decreased the binding forces, friction losses and wear on the vane tip, but increased vane stresses. The results also indicate that most of the friction loss occurs at the vane tip with additional friction loss on the vane sides. The viscous loss caused by the oil film between the double vanes is so small that it can be neglected in engineering calculations. The ratio of the upper vane thickness to the lower vane thickness is one of the most important parameters for the twin-piece vane machine. Analysis of the influence of this ratio on the forces, friction, wear and strength of the vanes was used to optimize the thickness ratio for the twin-piece vane machine.
Optimal Sensor Placement Methodology for Identification with Unmeasured Excitation
Authors: Yuen Ka-Veng , Katafygiotis Lambros S. , Papadimitriou Costas , Mickleborough Neil C.
Published: July 2002

A methodology is presented for designing cost-effective optimal sensor configurations for structural model updating and health monitoring purposes. The optimal sensor configuration is selected such that the resulting measured data are most informative about the condition of the structure. This selection is based on an information entropy measure of the uncertainty in the model parameter estimates obtained using a statistical system identification method. The methodology is developed for the uncertain excitation case encountered in practical applications for which data are to be taken either from ambient vibration tests or from other uncertain excitations such as earthquake and wind. Important issues related to robustness of the optimal sensor configuration to uncertainties in the structural model are addressed. The theoretical developments are illustrated by designing the optimal configuration for a simple 8-DOF chain-like model of a structure subjected to an unmeasured base excitation and a 40-DOF truss model subjected to wind/earthquake excitation.
The Process Window for Reference Free Part Encapsulation
Authors: Lee Elmer , Valdivia Paula , Fan Winston , Sarma Sanjay E.
Published: July 2002

Reference Free Part Encapsulation (RFPE) is an automatic, universal workholding process developed by the authors and by researchers at Berkeley. In RFPE, a block of filler material encapsulates the workpiece and provides a fixturing surface, and after each machining operation, the filler block is re-filled with material to restore it to a perfect block. The objective of this research is to compute the process parameter window for RFPE. We examine the effect of process parameters such as the injection temperature, the preheating temperature, the cooling rate and the pressure on the effectiveness of the process. We show that when the temperatures are too low, or if the mold is cooled too much or too rapidly, the newly added material does not weld properly to the original encapsulation. If the temperatures are too great, then the entire encapsulation is likely to melt and lose location. The injection pressure, meanwhile, affects the surface finish of the process, and therefore the accuracy. We develop models to understand the effects of these parameters on process performance and design experiments to verify these predictions. Using these techniques, we determine the acceptable parameter windows for the process.
Using Dynamic Analysis for Compact Gear Design
Authors: Lin Ping-Hsun , Lin Hsiang Hsi , Oswald Fred B. , Townsend Dennis P.
Published: July 2002

This paper presents procedures for designing compact spur gear sets with the objective of minimizing the gear size. The allowable tooth stress and dynamic response are incorporated in the process to obtain a feasible design region. Various dynamic rating factors were investigated and evaluated. The constraints of contact stress limits and involute interference combined with the tooth bending strength provide the main criteria for this investigation. A three-dimensional design space involving the gear size, diametral pitch, and operating speed was developed to illustrate the optimal design of spur gear pairs. The study performed here indicates that as gears operate over a range of speeds, variations in the dynamic response change the required gear size in a trend that parallels the dynamic factor. The dynamic factors are strongly affected by the system natural frequencies. The peak values of the dynamic factor within the operating speed range significantly influence the optimal gear designs. The refined dynamic factor introduced in this study yields more compact designs than AGMA dynamic factors.
Modal Analysis for Beam Bundle in Fluid
Authors: Zhang R. J. , Wang W. Q. , Hou S. H. , Chan C. K.
Published: July 2002

In the present paper, a 3-D homogenized model for beam bundle in fluid is developed and formulated in terms of fluid velocity potential and displacement of beams as fundamental unknowns. It can be seen that the homogenized model is associated with a set of finite element equations in the form of a conservative gyroscopic system. Based on these equations, an algorithm for the modal analysis and the dynamic response analysis of the beam bundle is also given. It is found that both the displacement and the fluid pressure response of the bundle have a similar relation with time, but different amplitudes.
On the Determination of the Angular Orientation of a Vertebra
Authors: Goris B. C. E. , Kuipers M. , De Vries J. , Wever D. J. , Verkerke G. J. , Veldhuizen A. G.
Published: July 2002

In this paper we consider the spatial orientation of vertebrae. We take the view that, in determining their rotation angles from X-rays, the procedure applied by Drerup yields the most reliable empirical results, viz. the three angles through which a vertebra rotates about its own symmetry axes in a specific sequence. With a view to the further use of this information to analyze deformations or the motion of a spine we recommend that the Drerup angles be converted into the well-known Eulerian angles. How this can be done is the subject of this report.
Optimal Boundary Control of an Axially Moving Material System
Authors: Fung Rong-Fong , Chou Jyh-Horng , Kuo Yu-Lung
Published: July 2002

The objective of this paper is to develop an optimal boundary control strategy for the axially moving material system through a mass-damper-spring (MDS) controller at its right-hand-side (RHS) boundary. The partial differential equation (PDE) describing the axially moving material system is combined with an ordinary differential equation (ODE), which describes the MDS. The combination provides the opportunity to suppress the flexible vibration by a control force acting on the MDS. The optimal boundary control laws are designed using the output feedback method and maximum principle theory. The output feedback method only includes the states of displacement and velocity at the RHS boundary, and does not require any model discretization thereby preventing the spillover associated with discrete parameter models. By utilizing the maximum principle theory, the optimal boundary controller is expressed in terms of an adjoint variable, and the determination of the corresponding displacement and velocity is reduced to solving a set of differential equations involving the state variable, as well as the adjoint variable, subject to boundary, initial and terminal conditions. Finally, a finite difference scheme is used to validate the theoretical results.
Fluid Flow Equations for Rotordynamic Flows in Seals and Leakage Paths
Authors: Hsu Y. , Brennen C. E.
Published: July 2002

Fluid-induced rotordynamic forces produced by the fluid in an annular seal or in the leakage passage surrounding the shroud of a pump or turbine, are known to contribute substantially to the potential excitation forces acting on the rotor. The present research explores some of the important features of the equations governing bulk-flow models of these flows. This in turn suggests methods which might be used to solve these bulk-flow equations in circumstances where the linearized solutions may not be accurate. This paper presents a numerical method for these equations and discusses comparison of the computed results with experimental measurements for annular seals and pump leakage paths.
Creep Rupture Due to Material Damage by Cavitation
Authors: Ragab A. R.
Published: July 2002

A phenomenological model to predict creep rupture times, based on material damage due to void growth and coalescence is presented. The model employs the Gurson-Tvergaard yield function together with the Norton-Baily power creep law. Rupture occurs at the end of a tertiary creep stage when the load-carrying capacity of the test-piece vanishes. Formulations for both uniaxial and triaxial conditions are given. Comparisons among the predictions of the present model and experiments for a vast number of data points indicate satisfactory agreement. A relation incorporating steady-state creep rate, rupture strain and rupture time is suggested. Furthermore acceptable correlation of the creep-rupture strength and creep strength to cause a specified creep strain is obtained.
Asymptotic Stress Fields for Stationary Cracks Along the Gradient in Functionally Graded Materials
Authors: Parameswaran V. , Shukla A.
Published: July 2002

Stress field for stationary cracks, aligned along the gradient, in functionally graded materials is obtained through an asymptotic analysis coupled with Westergaard’s stress function approach. The first six terms of the stress field are obtained for both opening mode and shear mode loading. It is observed that the structure of the terms other than r−1/2 and r0 are influenced by the nonhomogeneity. Using this stress field, contours of constant maximum shear stress are generated and the effect of nonhomogeneity on these contours is discussed.
Width-Wise Variation of Magnetic Tape Pack Stresses
Authors: Lee Y. M. , Wickert J. A.
Published: July 2002

A model is developed for predicting the stress and displacement fields within a magnetic tape pack, where those quantities are allowed to vary in both the pack’s radial and transverse (cross-tape) directions. As has been the case in previous analyses based upon one-dimensional wound roll models, the present approach accounts for the anisotropic and nonlinear constitutive properties of the layered tape, and the incremental manner in which the pack is wound. Further, such widthwise variation effects as differential hub compliance and nonuniform winding tension, which can be significant in data cartridge design, are also treated in the model. The pack is analyzed through a two-dimensional axisymmetric finite element model that couples individual representations of the hub/flange and layered tape substructures. The bulk radial elastic modulus of the tape, which depends on the in-pack radial stress, is measured for a variety of media samples, and a reduced-order model is developed to capture the nonlinear modulus-stress correlation. The stiffness matrix of the hub/flange at its interface with the media provides a mixed boundary condition to the tape substructure. In this manner, design-specific hubs can be readily analyzed, and criteria for their optimization explored. Simulations of several cartridge designs are presented, and the roles of hub compliance and wound-in tension gradient in setting the pack’s stress field and cross-tape width change are discussed.
A Novel Injectable Collagen Matrix: In Vitro Characterization and In Vivo Evaluation
Authors: Laude Damien , Odlum Kevin , Rudnicki Stewart , Bachrach Nathaniel
Published: July 2002

We present here a unique engineered collagen formulation that is injectable and compacts into a porous viscoelastic solid after implantation, achieving completely focal application without cross-linking. This implant provides a cohesive continuously porous matrix, as demonstrated by permeability and compression experiments. Those experiments also provide initial mechanical characterization of the material and establish the ability to modify these essential properties by design. Further, the short-term compaction and long-term stability of the implant in vivo in terms of both physical and histological responses are assessed in an animal model to demonstrate the mechanism of action and long-term persistence of this novel material. [S0148-0731(00)00403-9]
Probabilistic Mesomechanics for High Cycle Fatigue Life Prediction
Authors: Tryon Robert G. , Cruse Thomas A.
Published: July 2002

This paper presents an analytical modeling approach to characterize and understand high cycle fatigue life in gas turbine alloys. It is recognized that the design of structures subjected to fatigue cannot be based on average material behavior but that designs must consider −3σ or some other appropriate extreme value (tail of the distribution) loading and/or material properties. Thus, a life prediction capability useful in a design application must address the scatter inherent in material response to fatigue loading. Further, the life prediction capability should identify the key micromechanical variables that are critical in the tail of the materials durability distribution. The proposed method addresses the scatter in fatigue by investigating the microstructural variables responsible for the scatter and developing analytical and semi-analytical models to quantitatively relate the variables to the response. The model is general and considers the entire range of damage accumulation sequences; from crack nucleation of the initially unflawed structure to final fast fracture. [S0094-4289(00)01302-5]
Flutter Limits and Behavior of a Flexible Thin Sheet in High-Speed Flow— II: Experimental Results and Predicted Behaviors for Low Mass Ratios
Authors: Yamaguchi Nobuyuki , Sekiguchi Tooru , Yokota Kazuhiko , Tsujimoto Yoshinobu
Published: July 2002

Flutter phenomena of flexible thin sheets such as paper swept by wind are studied for a wide range of mass ratios by an analytical method developed by the authors. The analytical results explain well the tendencies found in the experimental data. Furthermore, the flutter behaviors for very low mass ratios are predicted to tend to deviate far from those for ordinarily stiff materials, which are attributed to the effects of both the fluid friction and the added mass effect by surrounding fluid in addition to the ordinary governing effects for higher mass ratios, i.e., elasticity, inertia force, and fluid pressure. [S0098-2202(00)01201-3]
An Introduction to Burmester Field Theory
Authors: Mlinar John R. , Erdman Arthur G.
Published: July 2002

This paper introduces the Burmester field for motion-generation dyads with four design positions. The Burmester field is the region swept by a Burmester curve as one or more of the design positions varies. The geometric features of the Burmester field are discussed and shown to be related to the poles. The most significant feature are anchor poles that remain stationary as the design positions are changed. The envelope of the Burmester field found with the variation of a single design parameter is developed. This work demonstrates that the envelope of the Burmester field consists of segments of Burmester curves and segments found using envelope theory. A number of examples are presented and discussed. [S1050-0472(00)00501-8]
Leak-Before-Break: What Does It Really Mean?
Authors: Wilkowski Gery
Published: July 2002

Leak-before-break (LBB) is a term that has been used for decades in reference to a methodology that means that a leak will be discovered prior to a fracture occurring in service. LBB has been applied to missile casings, gas and oil pipelines, pressure vessels, nuclear piping, etc. LBB also has several technical definitions. For instance, LBB can occur for an axial flaw in a pipe where the penetration of the wall thickness will result in a stable axial through-wall crack. This is LBB under load-controlled conditions. LBB could also occur for a circumferential crack in a pipe with high thermal expansion stresses. This might be LBB under compliant displacement-controlled conditions. Finally, LBB might occur when the flaw is stable under normal operating conditions and remains stable when there is a sudden dynamic event (i.e., seismic loading). This might be a time-dependant inertial LBB analysis. These analyses are deterministic, and could be extended to probabilistic evaluations as well. This paper describes some of the technical LBB approaches, applications, and significance of the methodology used in the applications. [S0094-9930(00)01603-6]
AU4 PAN-based Carbon Fiber by Core Level and Valence Band XPS
Authors: Xie Yaoming , Sherwood Peter M. A.
Published: July 2002

Hercules AU4 PAN-based carbon fiber surface was analyzed with both core level and valence band XPS. Compared to Du Pont and Amoco's pitch-based carbon fibers with different modulus, the AU4 fiber had more oxidized components on the surface than the pitch-based carbon fibers. [See Y. Xie and P. M. A. Sherwood, Appl. Spectrosc. 43, 1153 (1989); Chem. Mater. 1, 417 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992).] The AU4 PAN-based fiber had a much less graphitic structure in both the surface and the bulk than the pitch-based fibers as evidenced by both XPS and XRD. It also had a small amount of nitrogen in its structure, but no nitrogen was found on the pitch-based carbon fiber surfaces. Our previously reported work [Y. Xie and P. M. A. Sherwood, Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992)], showed that the XPS valence band spectra were more sensitive to chemical environment on the carbon fiber surface than core level spectra and could be well interpreted by X–α calculations with model compounds. In this work, the valence band spectrum showed that there were nitrogen and at least two different types of oxygen species on the AU4 fiber surface.
Lead Zirconate–Lead Titanate (PbZrO3–PbTiO3) Thin Film Prepared by the Sol-gel Process by AES
Authors: Bozack Michael J.
Published: July 2002

An Auger spectrum of the lead zirconate titanate ferroelectric thin film PbZrO3–PbTiO3 (PZT) is presented. The film was prepared by the sol-gel process on a sputtered Pt substrate. PZT is currently under investigation for use in nonvolatile semiconductor memories. Random access memory based on PZT rests upon the ability of ferroelectric material to possess two distinct polarizations which can remain in either state without an electric power supply.
Polytetrafluoroethylene Characterized by XPS, with Mg Source
Authors: Beard Bruce C. , Brizzolara Robert A.
Published: July 2002

Polytetrafluorethylene (PTFE) is a technologically important material employed for broad applications due to its exceptional properties for lubrication, insulation, and chemical inertness. With regard to surface analysis, PTFE has been found to provide a ready standard source for the x-ray photoelectron F 1s line in a polymeric matrix. A previous submission [M. Ackeret, Surf. Sci. Spectra 1, 100 (1992)] examined the uniformity of the atomic composition over the surface layers by angle dependent XPS analysis of the C 1s and F 1s lines. In this submission we wish to present the photoelectron transitions by Mg Kα radiation.
Characterization of Polystyrenes (5 and 40 kDa) Functionalized with a Perfluorinated Endgroup by TOF-SIMS: Effects of Molecular Weight
Authors: Belu A. M. , Hunt M. O. , DeSimone J. M. , Linton R. W.
Published: July 2002

TOF-SIMS measurements of 5 and 40 kDa polystyrene functionalized with a perfluoroalkyl endgroup are presented. Fragment signals in the low mass range are observed for both 5 and 40 kDa samples, using monolayer sample preparation on a silver substrate. Additionally for the 5 kDa sample, intact oligomer signals in the high mass range and chain cleavage signals in the intermediate mass range are generated. The successful functionalization of the polystyrene with the perfluoroalkyl endgroup can be confirmed by the masses at which the intact oligomer signals arise.
Fe 2p Core-Level Spectra for Pure, Epitaxial α-Fe2O3(0001), γ-Fe2O3(001), and Fe3O4(001)
Authors: Chambers S. A. , Kim Y. J. , Gao Y.
Published: July 2002

We have measured high-energy resolution Fe 2p and O 1s photoemission spectra and high-angular resolution Fe 2p and O 1s photoelectron diffraction angular distribution for the following iron oxide films grown by molecular beam epitaxy: α-Fe2O3/α-Al2O3(0001), γ-Fe2O3/MgO(001), and Fe3O4/MgO(001). The combination of these two techniques allows the crystallinographic quality of the near-surface region to be determined for each phase prior to measurement and interpretation of the core-level spectra. These spectra thus constitute state-of-the-art energy-resolved data on phase-pure, crystallographically well-defined iron oxides.
Analysis of chlorine-containing plasmas applied in III/V semiconductor processing
Authors: Franz Gerhard , Kelp Agnes , Messerer Peter
Published: July 2002

Capacitively coupled discharges of strongly reactive atmospheres containing mixtures of boron trichloride and chlorine are investigated with optical emission spectroscopy and self-excited electron resonance spectroscopy. This analyzes the whole area spanned by these gases and their impact on important plasma parameters like plasma density, electron temperature, and electron collision rate with neutrals. Using these data, roughly calculated cross sections for these gases are obtained in the low-energy region. Molecular chlorine ions, Cl2+, are evidently present to a preponderant amount as a main agent, which are accompanied by chlorine radicals, Cl(I), in mixtures with chlorine. Absolutely no chlorine ions could be found in the plasma which referred to the effective cooling of the Cl-containing species rather than the nonexistence of these species.
Ni3Al, Ni3Ga, Ni3In, and NiGa by XPS
Authors: Hsu L.-S.
Published: July 2002

X-ray photoelectron spectroscopy measurements of the principal core levels for Ni3Al, Ni3Ga, Ni3In, and NiGa polycrystals are presented.
Characteristics of diodes prepared using epitaxial CoSi2 as a boron diffusion source
Authors: Kim Gi Bum , Kwak Joon Seop , Baik Hong Koo , Lee Sung-Man
Published: July 2002

The effect of formation temperature of epitaxial CoSi2 in the Co/Ti/Si system on electrical characteristics of a p+n junction diode has been investigated. When the silicide formation temperature was 800 °C, a very low reverse leakage current density of 11 nA/cm2 at a bias of −5 V was obtained. However, when the temperature was 900 °C, the reverse leakage current was increased by more than three orders of magnitude. This was attributed to the formation of a Ti-rich phase at the surface by the reaction between the Co–Ti–Si phase and CoSi2 at 900 °C. The Ti-rich phase acted as a dopant sink, and suppressed the diffusion of boron to the CoSi2/Si interface. This caused very shallow junction depth with a low boron concentration at the region directly below the Ti-rich phase, followed by generation of a large reverse leakage current.
Emission sensitivity to tip position of Spindt-type field emitters
Authors: Xie Chenggang , Wei Yi , Lucero Rudy , Woodburn Robert
Published: July 2002

The emission characteristics of the Spindt-type field emitter are investigated as a function of the tip position with respect to the gate. The tip position is varied by either changing the hole diameter in the photomask or the dielectric layer thickness. Under low anode field, the measured emission current is sensitive to the tip position and drops quickly as the tip rises above the middle of the gate, which is consistent with the computer simulation result. Under high anode field, the computer simulation result shows that the emission increases for some distance above the gate electrode and then slowly falls off with increasing tip height. There is a “flat” region where emission is less sensitive to the tip position. The array with tall tips shows better emission uniformity. Two different types of emission patterns are observed for short and tall tips. The short tips show large blurry spots and the tall tips small sharp spots.
Sheet resistance nonuniformity for ionized titanium deposition
Authors: Ross Keith A. , Thimm Peter
Published: July 2002

A combination of recipe power and pressure in an ion metal plasma sputter deposition chamber has reduced average within-wafer sheet resistance nonuniformity approximately 40% to a value of 3.1%±0.2%. This result was obtained for a new polished target and nonknurled coil assembly operated over one coil life.
Electroreflectance and photoreflectance studies of surface Fermi level and surface state densities of InP SIN+ structures
Authors: Hwang W. C. , Cheng Y. J. , Wang Y. C. , Hwang J. S.
Published: July 2002

The built-in electric fields, surface Fermi level, and surface state density of a series of InP surface-intrinsic-n+ structures are calculated from the Franz–Keldysh oscillations of the modulation spectra of photoreflectance (PR) and electroreflectance (ER). Those results indicate that for samples with similar doping concentrations in the buffer layer and the substrate, the only built-in electric field across the top layer increases as their top layer thickness decreases. The surface Fermi level, however, remains roughly constant. For samples with a semi-insulated substrate, two built-in electric field exist separately in the top layer and at the interface between the buffer layer and the substrate. In addition, ER spectra are taken with the modulation electric field across the top layer. Although the built-in electric field across the top layer derived from the ER spectra increases as the top layer thickness decreases, the surface Fermi level, again, remains roughly constant. An approach of room temperature photoreflectance, based on the thermionic-emission theory and the current transport theory, is employed to estimate the surface state density. The surface state density of the InP SIN+ structure is found to diminish with an increase in the thickness of the top layer.
Thermal stability in diamond-like carbon coated planar electron field emission arrays
Authors: Lin Chin-Maw , Chang Shoou-Jinn , Yokoyama Meiso , Lin I-Nan
Published: July 2002

Diamond-like carbon (DLC) films fabricated by a pulsed laser deposition process are a very promising base material for a field emitter. An electron field emission array (FEA) with planar structure is necessary to utilize DLC materials as electron emitters. Thus, the behavior of DLC films must be examined during the elevated temperatures of the FEA packaging process. In this work, thermal annealing up to 500 °C is carried out in a nitrogen ambient to investigate the thermal stability of the field emission. Experimental results indicate that the resulting emission current remains stable as compared with the emission characteristic of nonannealed DLC films.
Power requirements of resistance-heated intermetallic evaporation sources
Authors: Parent Edward D.
Published: July 2002

There is a need in the metallizing industry for a rapid method, based on sound theory, for determining the voltage and current requirements for the operation of resistance-heated intermetallic aluminum evaporation boats. This paper shows how these power requirements can be adequately predicted in terms of operating temperature, two partially reduced dimensional parameters and the resistivity of the composite material. A solution of the total heat-flow equation for a model situation with appropriate simplifications and assumptions is presented. Experimental data are fitted to this simplified equation and the resultant calculated data are presented in graphical form suitable for generating computer tabulated data for all possible boat geometries and resistivities of Sylvania Intermetallic Composites ♯17 or ♯18.
Vacuum Stream Degassing of Molten Aluminum
Authors: Hellier S. J. , Bennett G. H. J.
Published: July 2002

The design and operation of a small-scale stream degassing facility for removing solute hydrogen from molten aluminum are described. It is shown that an aluminum melt may be successfully degassed by passing it through a vacuum in the form of a thin continuous cylindrical stream. Solute hydrogen removal is improved by increasing the specific surface area of the stream and also by increasing the height of fall of the stream up to an optimum value. Increasing the height of fall beyond the optimum does not result in a further improvement in hydrogen removal, and can in fact lead to poorer degassing than that obtained using shorter streams. This is associated with fracture of the longest streams during fall. The rate of hydrogen removal increases as the stream temperature is reduced. Using a 1.6- mm-diam orifice and 57-cm height of fall, 2 kg melts of 99.99% pure aluminum at 750°C, containing up to and over 0.5  Ncm3/100 g of hydrogen, were stream degassed in a vacuum of 1 Torr to levels near 0.1 Ncm3/100 g. Hydrogen removal from the unbroken streams appears to follow second-order kinetics.
An Examination of Electrode-Change Practice in Electroslag Melting
Authors: Jackson R. O. , Mitchell A. , Luchok J.
Published: July 2002

An examination of the unsteady-state heat balanced of an ESR furnace during a power interruption has been made. The results of this study show that the ingot heat balance during an electrode change may be characterized by a single term, the volume fraction of liquid solidified during the interruption. The application of this term to ESR and VAR practice is demonstrated. The structure and composition of ingot metal solidified during this change can be related to the local temperature gradients and solidification rate during the change. In turn, this may be related to the steady-state liquidus isotherm and the volume fraction solidified. The role of the local segregation coefficient in determining the maximum tolerable electrode change time is clearly demonstrated by the above parameters. The general relation of the above mechanisms to the electrode-change method is discussed for some practical cases. The engineering and economic problems associated with electrode-change practice are detailed. It is concluded that although there are many instances where a properly engineered electrode-change method may be used with no adverse effects in the ingot, the general applicability of the method is in doubt.
A Discussion of the Paper “The Role of Inclusions on Mechanical Properties in High-Strength Steels”
Authors: Porter L. F.
Published: July 2002

The authors show that at high tensile strength fracture toughness is insensitive to steel cleanliness, and reduction of area is very sensitive to steel cleanliness. These conclusions are generally substantiated by work conducted at U. S. Steel. The U. S. Steel work amplifies that reported in the subject paper by examining the effect of residual elements (cleanliness) on the reduction of area and fracture toughness of 18Ni maraging steels and the effect of prior-austenite grain size and residual-element content on the reduction of area and fracture toughness of high-strength quenched and tempered alloy steels. The U. S. Steel work shows that for the maraging and alloy steels studied, reduction-of-area values are very sensitive to residual-element level but not affected much by tensile-strength levels in the range 230–300 ksi. The fracture toughness of the maraging steels shows a sensitivity to residual-element level that decreases as the strength is raised. The steels appear to reach a point of complete insensitivity to residual-element level at a tensile strength of 310 ksi. At this strength, the fracture toughness approaches a KIc value of 50 ksi( in.)12. The fracture toughness of the alloy steels is insensitive to residual-element level throughout the tensile-strength range 230–320 ksi, but is sensitive to prior-austenite grain size. The grain-size sensitivity decreases as the strength level increases and appears to reach a point of complete insensitivity at a tensile strength of about 310 ksi. Again, the fracture toughness of the steels at a tensile strength of 310 ksi approaches a KIc value of approximately 50 ksi in.12. It is concluded that lowering residual-element levels by vacuum melting should improve the fracture toughness of maraging steels at tensile strengths below 310 ksi but will probably not improve the fracture toughness of quenched and tempered alloy steel at tensile strengths in the range 230 ksi and higher. Lowering residual elements by vacuum melting improves the ductility, as measured by reduction of area, of both maraging and alloy steels over the entire range of strengths studied. Reduction of area is not very sensitive to tensile strength in the range studied.
Improved Melting and Casting Procedures for a Cobalt-Base Magnetic Alloy
Authors: Moak D. P. , Pfeifer W. H. , Hildebrand W. J. , Sewall P. J. , Cianelli D. P. , King G. L.
Published: July 2002

One component of a very intricate central station telephone switching system contains a hard magnetic alloy of the composition cobalt-12 wt% iron-4 wt% gold. Problems were encountered during the final stages of the fabrication of the alloy to final form (0.00050 in.×0.0054 in.  tape) and during subsequent assembly of this product. Extensive failure analyses were performed to identify the nature of the problems, and for the most part, the causative factors were traced to the induction melting and casting practices employed for initial synthesis of the alloy. The major problems addressed during the melting and casting research were inclusions and centerline porosity in the ingots prepared for subsequent fabrication. Since the most likely source of inclusions can be related to melting crucibles, sprues, runners, gates, etc., initial attention was directed toward these areas. Sprues, runners, and gates were eliminated, and high-density, stable crucible was employed. Massive copper molds were used and ceramic hot tops were eliminated. Although several molding variables were investigated, centerline porosity (secondary piping) was eliminated only by very controlled pouring rates to effect directional solidification. In conclusion some final yield data that relate to the improved vacuum melting and casting techniques developed are presented.
Activated Reactive Evaporation Process for High Rate Deposition of Compounds
Authors: Bunshah R. F. , Raghuram A. C.
Published: July 2002

Activated reactive evaporation is a new process developed for the high rate deposition of compounds. It circumvents problems associated with direct evaporation of compounds. Metal vapors from high rate evaporation sources are reacted with a gas in the vapor phase to form and deposit compounds. The vapor phase reaction has to be activated by ionization of the reacting species, i.e., metal vapor and gas in the reaction zone. The steps of compound synthesis and compound deposition are thus separated. Control of deposit stoichiometry, e.g., [C/M] ratio for TiC synthesis is readily achieved by controlling the relative amounts of reactants. Results on the synthesis of carbides, oxides, and nitrides are presented.