A Scanning-Probe Technique for Mapping the Hardness of Lead-Free Solders

2014 ◽  
Vol 1652 ◽  
Author(s):  
Jennifer L. Hay ◽  
Carlos Morillo ◽  
Julie Silk
Keyword(s):  
Solder Joint ◽  
Three Dimensional ◽  
Local Stress ◽  
Information Storage ◽  
Scanning Probe ◽  
Gold Plating ◽  
Nano Indentation ◽  
Scanned Images ◽  
Lead Free Solders ◽  
Force Displacement

ABSTRACTA rapid nano-indentation measurement technique is employed to produce surface maps of hardness. Each indentation cycle requires less than three seconds, including surface approach, contact detection, force application, withdrawal, and movement to the next indentation site. Traditional nano-indentation analyses are applied to the force-displacement measurements from each indentation, but information storage and presentation owe much to scanning-probe technology. Consequently, this nano-indentation technique produces three-dimensional images of mechanical properties which are stored and manipulated just like scanned images.In the present work, we use this technique to map the hardness of a SAC 305 solder joint with gold plating. After extended isothermal aging, the solder joint comprises three constituents: a tin-rich matrix, a bulk intermetallic AuSn4, and an interfacial intermetallic (Cu, Ni, Au)6Sn5. The softest material is the tin-rich matrix, which has a hardness of 0.51±0.07 GPa. The hardness of the bulk intermetallic is 2.12±0.18 GPa. The interfacial intermetallic has extraordinary hardness— greater than 8 GPa. Under uniform plastic strain, the mismatch in hardness between the interfacial intermetallic and surrounding material may increase the local stress intensity factor which drives interfacial fracture.

Finite Element Modeling for Steel Cord Analysis in Radial Tires

2013 ◽  
Vol 41 (1) ◽  
pp. 60-79 ◽  
Author(s):  
Wei Yintao ◽  
Luo Yiwen ◽  
Miao Yiming ◽  
Chai Delong ◽  
Feng Xijin
Keyword(s):  
Finite Element ◽  
High Efficiency ◽  
Force Measurement ◽  
Three Dimensional ◽  
Local Stress ◽  
Tension Force ◽  
Center Line ◽  
Element Analysis ◽  
Design Variables ◽  
Steel Cord

ABSTRACT: This article focuses on steel cord deformation and force investigation within heavy-duty radial tires. Typical bending deformation and tension force distributions of steel reinforcement within a truck bus radial (TBR) tire have been obtained, and they provide useful input for the local scale modeling of the steel cord. The three-dimensional carpet plots of the cord force distribution within a TBR tire are presented. The carcass-bending curvature is derived from the deformation of the carcass center line. A high-efficiency modeling approach for layered multistrand cord structures has been developed that uses cord design variables such as lay angle, lay length, and radius of the strand center line as input. Several types of steel cord have been modeled using the developed method as an example. The pure tension for two cords and the combined tension bending under various loading conditions relevant to tire deformation have been simulated by a finite element analysis (FEA). Good agreement has been found between experimental and FEA-determined tension force-displacement curves, and the characteristic structural and plastic deformation phases have been revealed by the FE simulation. Furthermore, some interesting local stress and deformation patterns under combined tension and bending are found that have not been previously reported. In addition, an experimental cord force measurement approach is included in this article.

scholarly journals Fabrication of Eutectic Ga-In Nanowire Arrays Based on Plateau–Rayleigh Instability

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4616
Author(s):  
Takashi Ikuno ◽  
Zen Somei
Keyword(s):  
Integrated Circuits ◽  
Substrate Surface ◽  
Three Dimensional ◽  
Average Diameter ◽  
Nanowire Arrays ◽  
Scanning Probe ◽  
Rayleigh Instability ◽  
Simple Method ◽  
Flat Substrate ◽  
Metal Nanowire

We have developed a simple method of fabricating liquid metal nanowire (NW) arrays of eutectic GaIn (EGaIn). When an EGaIn droplet anchored on a flat substrate is pulled perpendicular to the substrate surface at room temperature, an hourglass shaped EGaIn is formed. At the neck of the shape, based on the Plateau–Rayleigh instability, the EGaIn bridge with periodically varying thicknesses is formed. Finally, the bridge is broken down by additional pulling. Then, EGaIn NW is formed at the surface of the breakpoint. In addition, EGaIn NW arrays are found to be fabricated by pulling multiple EGaIn droplets on a substrate simultaneously. The average diameter of the obtained NW was approximately 0.6 μm and the length of the NW depended on the amount of droplet anchored on the substrate. The EGaIn NWs fabricated in this study may be used for three-dimensional wiring for integrated circuits, the tips of scanning probe microscopes, and field electron emission arrays.

Finite Element Analysis of Stress Singularities in Attached Flip Chip Packages

2000 ◽  
Vol 122 (4) ◽  
pp. 301-305 ◽  
Author(s):  
A. Q. Xu ◽  
H. F. Nied
Keyword(s):  
Contact Angle ◽  
Finite Element ◽  
Glass Fiber ◽  
Flip Chip ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Local Stress ◽  
Stress Singularities ◽  
Element Analysis ◽  
Three Dimensional Finite Element

Cracking and delamination at the interfaces of different materials in plastic IC packages is a well-known failure mechanism. The investigation of local stress behavior, including characterization of stress singularities, is an important problem in predicting and preventing crack initiation and propagation. In this study, a three-dimensional finite element procedure is used to compute the strength of stress singularities at various three-dimensional corners in a typical Flip-Chip assembled Chip-on-Board (FCOB) package. It is found that the stress singularities at the three-dimensional corners are always more severe than those at the corresponding two-dimensional edges, which suggests that they are more likely to be the potential delamination sites. Furthermore, it is demonstrated that the stress singularity at the upper silicon die/epoxy fillet edge can be completely eliminated by an appropriate choice in geometry. A weak stress singularity at the FR4 board/epoxy edge is shown to exist, with a stronger singularity located at the internal die/epoxy corner. The influence of the epoxy contact angle and the FR4 glass fiber orientation on stress state is also investigated. A general result is that the strength of the stress singularity increases with increased epoxy contact angle. In addition, it is shown that the stress singularity effect can be minimized by choosing an appropriate orientation between the glass fiber in the FR4 board and the silicon die. Based on these results, several guidelines for minimizing edge stresses in IC packages are presented. [S1043-7398(00)00904-X]

scholarly journals COMPARATIVE ANALYSIS OF THREE-DIMENSIONAL NANOSTRUCTURE OF POROUS BIOCOMPATIBLE SCAFFOLDS MADE OF RECOMBINANT SPIDROIN AND SILK FIBROIN FOR REGENERATIVE MEDICINE

2015 ◽  
Vol 17 (2) ◽  
pp. 37-44 ◽  
Author(s):  
O. I. Agapova ◽  
A. E. Efimov ◽  
M. M. Moisenovich ◽  
V. G. Bogush ◽  
I. I. Agapov
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Scanning Probe ◽  
Porous Scaffolds ◽  
Volume Porosity ◽  
Integral Density ◽  
Regenerative Activity ◽  
Calculated Volume ◽  
Recombinant Spidroin

Aim.To perform a comparison of three-dimensional nanostructure of porous biocompatible scaffolds made of fibroinBombix moriand recombinant spidroin rS1/9.Materials and methods.Three-dimensional porous scaffolds were produced by salt leaching technique. The comparison of biological characteristics of the scaffolds shows that adhesion and proliferation of mouse fibroblastsin vitroon these two types of scaffolds do not differ significantly. Comparative experimentsin vivoshow that regeneration of bone tissue of rats is faster with implantation of recombinant spidroin scaffolds. Three-dimensional nanostructure of scaffolds and interconnectivity of nanopores were studied with scanning probe nanotomography (SPNT) to explain higher regenerative activity of spidroin-based scaffolds.Results.Significant differences were detected in the integral density and volume of pores: the integral density of nanopores detected on 2D AFM images is 46 μm–2    and calculated volume porosity is 24% in rS1/9-based scaffolds; in fibroin-based three-dimensional structures density of nanopores and calculated volume porosity were 2.4 μm–2  and 0.5%, respectively. Three-dimensional reconstruction system of nanopores and clusters of interconnected nanopores in rS1/9-based scaffolds showed that volume fraction of pores interconnected in percolation clusters is 35.3% of the total pore volume or 8.4% of the total scaffold volume.Conclusion.Scanning probe nanotomography method allows obtaining unique information about topology of micro – and nanopore systems of artificial biostructures. High regenerative activity of rS1/9-based scaffolds can be explained by higher nanoporosity of the scaffolds.

Solder Joint Reliability of Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys Solidified on Copper Substrates with Different Surface Roughnesses

2015 ◽  
Vol 830-831 ◽  
pp. 265-269
Author(s):  
Satyanarayan ◽  
K.N. Prabhu
Keyword(s):  
Solder Joint ◽  
Solder Matrix ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Cu Substrate ◽  
Cu Substrates ◽  
Free Solder ◽  
Substrate Surfaces ◽  
Lead Free Solders

In the present work, the bond strength of Sn-0.7Cu, Sn-0.3Ag-0.7Cu, Sn-2.5Ag-0.5Cu and Sn-3Ag-0.5Cu lead free solders solidified on Cu substrates was experimentally determined. The bond shear test was used to assess the integrity of Sn–Cu and Sn–Ag–Cu lead-free solder alloy drops solidified on smooth and rough Cu substrate surfaces. The increase in the surface roughness of Cu substrates improved the wettability of solders. The wettability was not affected by the Ag content of solders. Solder bonds on smooth surfaces yielded higher shear strength compared to rough surfaces. Fractured surfaces revealed the occurrence of ductile mode of failure on smooth Cu surfaces and a transition ridge on rough Cu surfaces. Though rough Cu substrate improved the wettability of solder alloys, solder bonds were sheared at a lower force leading to decreased shear energy density compared to the smooth Cu surface. A smooth surface finish and the presence of minor amounts of Ag in the alloy improved the integrity of the solder joint. Smoother surface is preferable as it favors failure in the solder matrix.

Influence Of Solder Joint Shape On The Thermo-Mechanical Reliability Of CSP's

2004 ◽  
Vol 1 (2) ◽  
pp. 53-63 ◽  
Author(s):  
Co van Veen ◽  
Bart Vandevelde ◽  
Eric Beyne
Keyword(s):  
Solder Joint ◽  
Force Constant ◽  
Local Stress ◽  
Simulation Software ◽  
Temperature Cycling ◽  
Circuit Board ◽  
Surface Evolver ◽  
Joint Shape ◽  
Profile Estimation ◽  
Analytical Expressions

Not only the stand-off height but also the shape of a solder joint has a strong influence on the joint reliability under temperature cycling. The shape determines the size of the local stress and strain concentrations. It is therefore very important to know well the joint shape after reflow. In a previous paper closed analytical expressions were derived for liquid bump shapes, as a function of pad size and bump height [1]. The bump deformation as a function of the chip weight could be derived from the force constant. In the present paper closed analytical expressions are derived for the force constant for liquid bumps having unequal spherical pad sizes. It turns out that the force constant for compression can be optimized as a function of the ratio of those pad sizes. The shape of the bump and especially the contact angle is of interest for modeling activities where geometrical effects do play a role. Furthermore from the variation in bumps heights on a chip an estimate can be made of the tilt of the chip after assembly. The solder profile estimation by the analytical expressions is validated by experimental results. Also a comparison with the solder profile estimation by the simulation software Surface Evolver is done. Both comparisons showed that the analytical estimation of the standoff height is very good as long as the gravitation energy contributed by the chip weight is less than 10% of the total energy. Finally, an example is shown where the analytical model and Surface Evolver are the geometrical input for a finite element model. The example considers a CSP assembled at both sides of the printed circuit board.

Numerical Optimization of Silicon Stacked Module for 3-D Packaging Applications

2008 ◽  
Vol 5 (2) ◽  
pp. 68-76
Author(s):  
Akella G.K. Viswanath ◽  
Xiaowu Zhang ◽  
Y.Y. Wang ◽  
S.W. Yoon ◽  
Navas Khan ◽  
...  
Keyword(s):  
Solder Joint ◽  
Functional Integration ◽  
Three Dimensional ◽  
Interfacial Stress ◽  
Electrical Performance ◽  
Thickness Variation ◽  
Element Analysis ◽  
Variation Of Parameters ◽  
Optimization Study ◽  
Electroplated Copper

Three-dimensional package format has gained more popularity for various applications because of the trend toward higher functional integration, miniaturization, and better electrical performance. This paper presents a design optimization study of a 3-D package using a silicon interposer. The package consists of three stacks with five dies. Electrical connections through the silicon interposers are done by through-silicone vias (TSVs) filled with electroplated copper. Initially, structural optimization of the package is conducted by a 2-D finite element analysis and later, statistical analysis is performed to estimate the coupled effects of parameters considered for the design. Carrier thickness variation is found to be the most significant effect on the package warpage. Interfacial stress between the copper plug and the silicon via hole has been investigated and reported. A 3-D model is constructed for the solder joint reliability study with SnAgCu material properties. Solder joint life with variation of parameters (i.e., board level underfill, higher standoff solder interconnect, and low CTE board) is studied, and all results are reported accordingly.

scholarly journals Influence of an Immersion Gold Plating Layer on Reliability of a Lead-Free Solder Joint

2005 ◽  
Vol 46 (12) ◽  
pp. 2725-2729 ◽  
Author(s):  
Ikuo Shohji ◽  
Hiroki Goto ◽  
Kiyotomo Nakamura ◽  
Toshikazu Ookubo
Keyword(s):  
Solder Joint ◽  
Lead Free ◽  
Lead Free Solder ◽  
Gold Plating ◽  
Free Solder ◽  
Plating Layer

scholarly journals A three-dimensional elastoplastic analysis of mixed-mode KI/KII around the crack front

2019 ◽  
Vol 300 ◽  
pp. 11002
Author(s):  
Luiz Fernando Nazaré Marques ◽  
Jaime Tupiassú Pinho de Castro ◽  
Luiz Fernando Martha ◽  
Marco Antonio Meggiolaro
Keyword(s):  
Crack Front ◽  
Mixed Mode ◽  
Three Dimensional ◽  
Local Stress ◽  
Mode I ◽  
Pure Mode ◽  
Mode Effects ◽  
Fatigue And Fracture ◽  
Edge Tension ◽  
Combined Mode

Engineering problems that involve fatigue crack growth and fracture frequently can be studied by taking into account only mode-I features. However, many important problems that involve combined mode I and II loadings cannot be properly analyzed by a pure mode-I approach, which in particular may not be sufficient to estimate fracture toughness for practical purposes in such cases. Such mixed-mode problems involve crack orientation and/or load conditions that lead to combined local Stress Intensity Factors (SIFs) KI/KII around the crack front. Using multiaxial crack tip condition characterized by the crack inclination angle βin a mixed-mode KI/KII modified single edge tension SE(T) specimen, such mixed-mode effects on plastic zone shapes, volumes and plastic work UPL are taken into account to evaluate problems that involve fatigue and fracture.

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