scholarly journals Mechanics Of Interfacial Crack Propagation In Microscratching

1996 ◽  
Vol 436 ◽  
Author(s):  
Maarten P. de Boer ◽  
John C. Nelson ◽  
William W. Gerberich
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Grain Boundary ◽  
Interfacial Crack ◽  
Strain Energy Release ◽  
Linear Elastic ◽  
Interfacial Cracks ◽  
Bending Strain ◽  
Diamond Indenter ◽  
Boundary Fracture

AbstractA new probing technique has been developed to test thin film mechanical properties. In the Microwedge Scratch Test (MWST), a wedge shaped diamond indenter tip is drawn along a fine line, while simultaneously being driven into the line. We compare microwedge scratching of Zone 1 and Zone T thin film specimens of sputtered W on SiO2. Symptomatic of its poor mechanical properties, the Zone 1 film displays three separate crack systems. Because of its superior grain boundary strength, the Zone T film displayed only one of these - an interfacial crack system. Using bimaterial linear elastic fracture mechanics, governing equations are developed for propagating interfacial cracks, including expressions for strain energy release rate, bending strain, and mode mixity. Grain boundary fracture strength information may be deduced from the Zone 1 films, while adhesion may be inferred from the Zone T films.

Thin film scratch testing in two dimensions—Experiments and analysis

1998 ◽  
Vol 13 (4) ◽  
pp. 1002-1014 ◽  
Author(s):  
Maarten P. de Boer ◽  
John C. Nelson ◽  
William W. Gerberich
Keyword(s):  
Thin Film ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Plane Strain ◽  
Interfacial Crack ◽  
Strain Energy Release ◽  
Two Dimensions ◽  
Displacement Curve ◽  
Narrow Strip ◽  
Interfacial Cracks

We have modified the microscratch test to create a near plane strain loading condition. In the Microwedge Scratch Test (MWST), a wedge-shaped diamond indenter tip is drawn along a fine line (i.e., narrow strip of film), while simultaneously being driven into the line. We compare microwedge scratching of zone 1 (voided grain boundaries) and zone T (metallurgical grain boundaries) thin film specimens of sputtered tungsten on thermally grown SiO2. Symptomatic of its weak grain boundaries, the zone 1 film displays three separate crack systems. Because of its superior grain boundary strength, the zone T film displayed only one of these—an interfacial crack system. By correlating fracture phenomena to signature events in the load-displacement curve, we develop governing equations for propagating interfacial cracks, including expressions for strain energy release rate, bending strain, and mode mixity. Grain boundary fracture causes zone 1 films to spall before a stable crack is formed. Zone T films survive the bending strains, and hence adhesions may be inferred from stable crack growth mechanics. We conclude by contrasting and comparing experimental results for plane strain indentation versus plane strain scratching.

Analysis of Interface Cracking in Flip Chip Packages With Viscoplastic Solder Deformation

2003 ◽  
Author(s):  
M. J. Heffes ◽  
H. F. Nied
Keyword(s):  
Flip Chip ◽  
Strain Energy Release ◽  
Solder Material ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
Interfacial Cracks ◽  
Fracture Parameters ◽  
Solder Bumps ◽  
Interface Cracking ◽  
Semiconductor Packages

This paper examines the modeling of viscoplastic solder behavior in the vicinity of interfacial cracking for flip chip semiconductor packages. Of particular interest is the relationship between viscoplastic deformation in the solder bumps and any possible interface cracking between the epoxy underfill layer and the silicon die. A 3-D finite element code, developed specifically for the study of interfacial fracture problems, was modified to study how viscoplastic solder material properties would affect fracture parameters such as strain energy release rate and phase angle for nearby interfacial cracks. Simplified two-layer periodic symmetry models were developed to investigate these interactions. Comparison of flip chip results using different solder material models showed that viscoplastic models yielded lower stress and fracture parameters than time independent elastic-plastic simulations. It was also found that adding second level attachment greatly increases the magnitude of the solder strain and fracture parameters. As expected, the viscoplastic and temperature dependent elastic-plastic results exhibited greater similarity to each other than results based solely on linear elastic properties.

The LEFM Concept for Interfacial Cracks Application to the Problem of Coating Delamination on Cylindrical Substrates

2012 ◽  
Vol 79 (3) ◽  
Author(s):  
Ruzica R. Nikolic ◽  
Jelena M. Djokovic
Keyword(s):  
Fracture Mechanics ◽  
Interfacial Crack ◽  
Axial Direction ◽  
Ceramic Coatings ◽  
Linear Elastic Fracture Mechanics ◽  
Turbine Engine ◽  
Linear Elastic ◽  
Interfacial Cracks ◽  
Coating Delamination ◽  
Elastic Fracture

In this paper the delamination of coating subjected to compressive stress on a cylindrical substrate is considered. This problem is particularly interesting in oxide coatings on wire elements exposed to extreme temperatures and in ceramic coatings on turbine engine blades or other components that operate at high temperatures. Using the results of Hutchinson (Hutchinson, 2001, “Delamination of Compressed Films on Curved Substrates,” J. Mech. Phys. Solids, 49, pp. 1847–1864) the aforementioned problem is discussed from the aspect of application of the linear elastic fracture mechanics (LEFM) concept for an interfacial crack. The energy release rate and mode mixity for the case of the coating delamination in the axial and radial directions are determined. It is shown that the results also depend on whether the substrate is convex or concave. Delamination in the radial direction in the case of the concave substrate is harder, but it is more likely when the substrate is convex. Delamination in the axial direction is equally likely in both cases. The results presented in this paper justify the application of the concept of linear elastic fracture mechanics for an interfacial crack for explaining the influence of the elastic characteristics of the substrate on the buckling delamination of the coating.

Modeling and Simulation of 3-D Interfacial Cracks by XFEM

2017 ◽  
Author(s):  
Himanshu Pathak ◽  
Akhilendra Singh ◽  
Indra Vir Singh ◽  
Sunny Zafar
Keyword(s):  
Mechanical Properties ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Interfacial Crack ◽  
Partition Of Unity ◽  
Integral Approach ◽  
Cylindrical Domain ◽  
Material Interface ◽  
Interfacial Cracks ◽  
Heaviside Enrichment

The structural integrity of multi-layered material depends on the mechanical properties and the fracture behaviour at the interface. The sudden jump in mechanical properties across the interface is the major source of failure in layered materials. An accurate evaluation of mixed-mode SIFs becomes essential for safe design of layered structure components. In this work, extended finite element method (XFEM) has been used to analyze interfacial cracked three-dimensional structures under mechanical loading. In XFEM, partition of unity enrichment concept is used to model a crack e.g. a crack surface is modeled by Heaviside enrichment function whereas a crack front is modeled by branch enrichment functions. Discontinuity due the presence of bi-material interface is modeled by the signed distance function. Modified domain based interaction integral approach has been used to evaluate the individual stress intensity factors. Three-dimensional cylindrical domain having an interfacial crack is taken for the simulations. A comparative analysis has been performed with and without an interface for an embedded penny shape crack. The effect of material interface on the SIFs has been analyzed in detail. Finally, a three-dimensional interfacial crack growth simulation has been performed for arbitrary shape crack.

Analysis of Interfacial Cracking in Flip Chip Packages With Viscoplastic Solder Deformation

2004 ◽  
Vol 126 (1) ◽  
pp. 135-141 ◽  
Author(s):  
M. J. Heffes ◽  
H. F. Nied
Keyword(s):  
Flip Chip ◽  
Strain Energy Release ◽  
Solder Material ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
Interfacial Cracks ◽  
Fracture Parameters ◽  
Solder Bumps ◽  
Interface Cracking ◽  
Semiconductor Packages

This paper examines the modeling of viscoplastic solder behavior in the vicinity of interfacial cracking for flip chip semiconductor packages. Of particular interest is the relationship between viscoplastic deformation in the solder bumps and any possible interface cracking between the epoxy underfill layer and the silicon die. A 3-D finite element code, developed specifically for the study of interfacial fracture problems, was modified to study how viscoplastic solder material properties would affect fracture parameters such as strain energy release rate and phase angle for nearby interfacial cracks. Simplified two-layer periodic symmetry models were developed to investigate these interactions. Comparison of flip chip results using different solder material models showed that viscoplastic models yielded lower stress and fracture parameters than time independent elastic-plastic simulations. It was also found that adding second level attachment greatly increases the magnitude of the solder strain and fracture parameters. As expected, the viscoplastic and temperature dependent elastic-plastic results exhibited greater similarity to each other than results based solely on linear elastic properties.

On the role of tin underlays for the prevention of thermal grooving in thin gold films

1986 ◽  
Vol 44 ◽  
pp. 732-733
Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff
Keyword(s):  
Thin Film ◽  
Free Surface ◽  
Grain Boundary ◽  
Beneficial Effect ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Distinct Advantage ◽  
Gold Films ◽  
Gold Thin Film

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

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