David J. Quesnel

Effect of solid-state intermetallic growth on the fracture toughness of Cu/63Sn-37Pb solder joints

The mode I chevron notch fracture toughness of Cu/63Sn-37Pb solder joints was measured as a function of solid state copper-tin intermetallic growth at the solder/copper interface. Soldered chevron notched bend samples were aged in a furnace at 170/spl deg/C to promote the intermetallic growth and the samples were tested at room temperature after 1, 3, 10, 30, and 75 days of growth. The total thickness of the interfacial intermetallic layer and the individual thicknesses of the component Cu/sub 6/Sn/sub 5/ and Cu/sub 3/Sn layers were monitored at each stage. The chevron notch fracture toughness is correlated with the intermetallic layer thickness measurements and the fracture surface morphology. The results show that at a total intermetallic layer thickness below 5 /spl mu/m, failure is dominated by microvoid coalescence in the solder, and intermetallic growth has little effect on the fracture toughness. At a total thickness exceeding 7 /spl mu/m, however, fracture occurs by cleavage of the interfacial intermetallic particles and the fracture toughness decreases steadily as the intermetallic layer thickness increases. With a total intermetallic layer thickness of 19 /spl mu/m, the chevron notch fracture toughness is only 30% of that measured for an as-soldered, nonaged solder joint.

Mode I fracture toughness testing of eutectic Sn-Pb solder joints

The mode I plane strain fracture toughness of Cu/63Sn-37Pb solder joints was measured using a technique based upon the ASTM standard methods for fracture toughness testing. A solder joint compact tension sample geometry was selected for the evaluation and each sample was manufactured using a capillary soldering system that provides excellent control over critical processing parameters. The mode I plane strain fracture toughness based on these tests is 8.36 MPa√m. Failure is dominated by microvoid nucleation in the solder and fracture of the intermetallic particles that are located at the solder/copper interface. The validity of the testing method used and the relevance of the results to solder joint reliability are discussed.

Stress distributions at the abrasive-matrix interface during tool wear in bound abrasive grinding : A finite element analysis

Abstract In bound-abrasive grinding, the abrasive particles are subjected to normal and frictional forces due to their interactions with the workpiece. These forces generate stresses at the abrasive particle-matrix interface (also referred to as “the interface” in the following text). Debonding, or fallout of abrasive particles, will be affected by the stress state at the interface, which is determined by the load on the particle, the wear of matrix material around each individual particle, and the wear of the particle itself. A two-dimensional finite element model is established to calculate the stress distributions at the interface. Given the particle geometry and the load distributed around the abrasive tip, the calculations show that a high stress state occurs at the interface close to the surface of the matrix, i.e. the junction of the matrix surface and the interface. The magnitude of stress at the tension side of the particle increases drastically when the matrix is worn away evenly on both sides of the particle. However, wear of the bond along only the leading or tension side of the interface does not affect the stress distribution significantly. Wear of the abrasive particle itself has only limited influence on the stress distribution.

Molecular Dynamic Modeling of Particle Adhesion

Abstract Molecular dynamic modeling was used to study the interactions between nanometer size two-dimensional particles in proximity to the surface of a two-dimensional crystal composed of the same material. The modeling was conducted by using triangular lattices of atoms that interact through a Lennard-Jones potential. The atoms were configured such that the particle consisted of a circle with 463 atoms. The crystal was in the shape of a rectangle and contained 442 atoms. The system was assumed to have periodic boundary conditions. It was first allowed to equilibrate with an assumed dimensionless kinetic energy per atom of 0.2 e. Subsequently, the particle was made to approach the surface at a velocity of 0.387 [sgrave]/t (corresponding to 6.25 m/s for argon), which is small compared with the speed of sound in the material. The approach was conducted in two modes: (1) centroidal displacement control at constant temperature and (2) free flight at the same intercentroidal velocity of approach. For each cas...

Particle adhesion and removal in electrophotography

Particle adhesion and removal is often controlled by the interplay of electrostatic forces, related to electrical charges on the particles, and electrodynamic forces, such as those arising from van der Waals interactions. In addition, when electrostatically detaching a charged particle from a substrate, the manner in which the electric field is applied can alter the charge on the particle, thus changing both the attractive and detachment forces. The effects are clearly illustrated in the transfer of a toned image from the photoconductor in an electrophotographic engine. This paper reviews present day understanding of the interplay between electrostatic and electrodynamic interactions, as they occur within the electrophotographic process, and presents the results of previous studies in a unified manner.

The adhesion of spherical particles: Contributions of Van Der Waals and electrostatic interactions

The forces needed to detach monodisperse spherical polystyrene particles having radii between approximately 1 μm and 6 μm from a polyester substrate were determined using electrostatic detachment. It was found that the removal force varied linearly with particle radius, as predicted by the JKR theory (K. L. Johnson, K. Kendall, and A. D. Roberts, Proc. R. Soc. London, Ser. A 324 , 301 (1971)). In addition, the work of adhesion, estimated from JKR theory, was found to be approximately 0.01 J/m 2 . This is a reasonable value for a system such as this. These results are, however, inconsistent with the predictions of models that assume that particle adhesion is dominated by electrostatic forces due to either a uniform charge distribution over the surface of the particle or localized charged patches.

Effects of Electrostatic and van der Waals Interactions on the Adhesion of Spherical 7 µm Particles

ABSTRACT The force needed to detach spherical particles having a number average diameter of 7.1 μm from a polymeric, photoconducting substrate was determined by ultracentrifugation. In the absence of any release agents applied to the substrate, it was found that only a small fraction of the particles could be removed from the substrate even at the highest centripetal accelerations (354,000 g). However, when the substrate was coated with a thin layer of a release aid (zinc stearate), the force needed to separate the particles from the substrate was greatly reduced, thereby allowing the detachment force to be determined. Under these conditions, it was found that the release force varied with the square of the particle charge-to-mass ratio. Moreover, it was also found by extrapolation that the detachment force at zero charge, corresponding to the residual van der Waals interactions, was finite. These results suggest that both van der Waals and electrostatic interactions affect the adhesion of particles and, for micrometer-sized particles, electrostatic forces can become dominant under some circumstances. Conversely, the large increase in the adhesion of the particles to the substrate, in the absence of a good release agent, suggests that van der Waals forces would often dominate adhesive interactions of particles in this size range.

Molecular Dynamic Simulation of Adhesional Release of Particles from Surfaces

Abstract The generalized form of the Lennard-Jones soft-sphere pair potential is used to examine the adhesional attachment and release behavior of particles on surfaces for materials of varying “ductility”. Using a two-dimensional simulation, with the repulsive term held constant at m = 12, the attractive term is varied from n = 2 to n = 10 at a constant binding energy to provide a controlled way of changing the effective range of interaction between atoms. Molecular dynamics simulates the placement of particles on a free surface and the subsequent removal of these particles by controlling the displacement of the center of mass. Simulations indicate that the longer-ranged removal forces literally tear out a chunk of the surface by pulling out a tether-like strand connecting the ball and plate. As the forces become shorter range, the size of the region of disturbed material after separation decreases until, at the shortest range, only three atoms are transferred and there is relatively little damage to the...

Synthesis and electrochemical study of sodium ion transport polymer gel electrolytes

This research demonstrates a new, high conductivity sodium ion polymer gel electrolyte (PGE), which is prepared using a solution casting technique. The prepared PGE consists of a plasticized polymer blend of poly(methyl methacrylate) (PMMA) and polycarbonate that serves as a framework to immobilize phase separated interconnected liquid rich regions of ethylene carbonate (EC) and propylene carbonate (PC). Portions of these liquids that remain dissolved in the polymer blend act as plasticizers while interconnected liquid regions provide an all-liquid conductive pathway. A loosely bonded sodium salt, sodium tetrafluoroborate (NaBF4), was added to the PGE to decrease the crystallinity of the polymer blend, thus lowering energy barriers for ion transfer in the blend and providing more charge carriers in the liquid rich phases to enhance the overall ionic conductivity of the PGE. Peak ionic conductivity of 5.67 × 10−4 S cm−1 was observed from electrochemical impedance spectroscopy measurements of a PGE with 25 wt% NaBF4 which is more than two orders of magnitude larger than the same PGE without NaBF4 that demonstrates a conductivity of 1.03 × 10−6 S cm−1. The temperature dependence of ionic conductivity agrees with the Arrhenius equation from 20 °C to 90 °C. The activation energies for PGEs with different concentrations of NaBF4: 5 wt%, 15 wt% and 25 wt% are found to be 0.13, 0.17 and 0.28 eV respectively. Cyclic voltammetry confirmed that the PGEs are electrochemically stable over a wide potential range of −5 V to +5 V. In addition, transference number measurements, whose values varied from 0.83 to 0.93, demonstrate that these PGEs are ionic conductive electrolytes. The findings of this study are consistent with the development of a sodium ion conductive electrolyte films that are promising for use in non-aqueous advanced energy storage applications.

Particle adhesion : applications and advances

Preface Biological Applications of Particle Adhesion Concepts 1. A Particle Adhesion Perspective of Metastasis B.J. Love and J.E. Forsten 2. Adhesion of Cancer Cells to Endothelial Monolayers: A Study of Initial Attachment Versus Firm Adhesion M.A. Moss and K.W. Anderson 3. Cell-Cell Adhesion of Erythrocytes F.R. Attenborough and K. Kendall 4. Particle-Induced Phagocytic Cell Responses are Material Dependent: Foreign Body Giant Cells vs Osteoclasts from a Chick Chorloallantoic Membrane Particle-implantation Model L .C. Carter, J.M. Carter, P.A. Nickerson Elastic and Viscoelastic Contributions to Understanding Particle Adhesion 5. The Bodys Response to Deliberate Implants: Phagocytic Cell Responses to Large Substrata Vs Small Particles R. Baier, E. Axelson, A. Meyer, L. Carter, D. Kaplan, G. Picciolo and S. Jahan 6. The Bodys Response to Inadvertant Implants: Respirable Particles in Lung Tissues R. Baier, A. Meyer, D. Glaves-Rapp, E. Axelson, R. Forsberg, M. Kozak and P. Nickerson 7. Measurement of the Adhesion of a Viscoelastic Sphere to a Flat Non-Compliant Substrate M. Reitsma. V.S.J. Craig and S. Briggs 8. Surface Forces and the Adhesive Contact of Axisymmetric Elastic Bodies A.-S. Huguet and E. Barthel 9. Finite Element Modeling of Particle Adhesion: A Surface Energy Formalism D.J. Quesnal and D.S. Rimai 10. Creep Effects in Nanometer-scale Contacts to Viscoelastic Materials: A Status Report W.N. Unerti Particle Surface Interactions that Influence Adhesion 11. Experiments and Engineering Models of Microparticle Impact and Deposition R.M. Brach, P.F. Dunn, and X. Li 12. The Adhesion of Irregularly-Shaped 8 m Diameter Particles to Substrates: The Contributions of Electrostatic and van der Waals interactions D.S. Riami, D.J. Quesnel and Reifenberger Electrical Conductivity Through Particles 13. Copper-based Conductive Polymers: A New Concept in Conductive Resins D.W. Marshall Exploring Particle Adhesion with Single Particle Experiments 14. Interactions Between Micron-sized Glass Particles and Poly (dimethyl siloxane) in the Absence and Presence of Applied Load G. Tolkka, G.M. Spinks and H.R. Brown 15. Atomic Force Microscope Techniques for Adhesion Measurements D.M. Schaefer and J. Gomez 16. Limitation of the Young-Dupre Equation in the Analysis of Adhesion Forces Involving Surfactant Solutions J. Drellch, E. Beech, A. Gosiewska and J.D. Miller 17. Mechanical Detachment of Nanometer Particles Strongly Adhering to a Substrate: An Application of Corrosive Tribology J.T. Dickinson, R.F. Harladi and S.C. Langford Advances in Controlling the Attachement and Removal of Groups of Particles 18. The Effect of Relative Humidity on Particle Adhesion and Removal A.A. Busnaina and T. Elsawy 19. The Effect of Time and Humidity on Particle Adhesion and Removal J.Tang and A.A. Busnaina