Evaluation of Strength in Joints of Silicon and Sapphire Coating Silicon

2013 ◽  
Author(s):  
Hideo Koguchi ◽  
Naoki Kimura
Keyword(s):  
Thermal Stresses ◽  
Electronic Device ◽  
Silicon Film ◽  
Sio2 Film ◽  
Nominal Stress ◽  
Slow Cooling ◽  
Environment Temperature ◽  
Bonding Area ◽  
Sapphire Plate ◽  
Silicon Resin

Recent electronic device packaging, for instance, Chip size package (CSP) has a bonded structure of IC chip and polymers, and delamination occurs frequently at the interface between IC and a resin. Furthermore, thermal stresses which are caused by a temperature variation in the bonding process of CSP and heat cycles for environment temperature will influence on the strength of interface. In the present paper, the delamination test for specimens with different bonding areas and geometries is carried out to investigate the strength of multi-layered joints. In particular, a silicon wafer is joined with a silicon-on-sapphire (SOS) plate by a resin. The SOS is composed of silicon film, SiO2 film and sapphire plate. The thicknesses of silicon film, SiO2 film and sapphire plate are 0.45μm, 0.2μm, 600μm, respectively. The joining strength in silicon, resin and SOS joints with triangular and rectangular bonding area is investigated. The triangular and rectangular shape bonding areas are 3mm2 and 12mm2, respectively. The bonded specimens are prepared under different cooling rate. Load is applied to the specimen so as to delaminate at the interfaces of SiO2 film and sapphire. From the delamination test, it is found that residual thermal stress and the geometry of bonding area affect the strength of interface. In the case of the triangular area specimen, delamination occurs at the interface between SiO2 film and sapphire plate in the silicon-resin-SOS specimen. The nominal stress for delamination is about 1.99MPa. In the case of rectangular bonding area specimen, delamination occurs at the interface between SiO2 film and sapphire plate in the silicon-resin-SOS specimen. Nominal stress for delamination is about 2.23MPa. From a comparison of the strength of joint for rapid and slow cooling conditions, it is found that the residual stress reduces the strength of joint.

Evaluation of the Strength of Interface for Multi-Layered Materials in Photonic Devices

2015 ◽  
Author(s):  
Hideo Koguchi ◽  
Naoki Kimura
Keyword(s):  
Numerical Analysis ◽  
Thermal Stresses ◽  
Electronic Device ◽  
Silicon Film ◽  
Unit Load ◽  
Slow Cooling ◽  
Element Analysis ◽  
Environment Temperature ◽  
Sapphire Plate ◽  
Critical Intensity

Recent electronic device packaging, for instance, CSP has a bonded structure of IC chip and polymers, and delamination occurs frequently at the interface between IC and a resin. Furthermore, thermal stresses which are caused by a temperature variation in the bonding process of CSP and heat cycles for environment temperature will influence on the strength of interface. In the present paper, the delamination test for specimens with different thicknesses of an interlayer is carried out to investigate the strength of multi-layered joints, and the critical value for the intensity of singularity at delamination of interface is determined through a numerical analysis using a boundary element analysis. In experiment, a silicon wafer is joined with a silicon-on-sapphire (SOS) plate by a resin. The SOS is composed of silicon film and sapphire plate. The joining strength in silicon, resin and SOS joints with a rectangular bonding area is investigated. The bonded specimens are prepared under different cooling rate. Load is applied to the specimen so as to delaminate at the interfaces of silicon film and sapphire. Delamination occurs at the interface between silicon film and sapphire plate in the specimen. Nominal stress for delamination is about 2.23–3.59 MPa. From a comparison of the strength of joint for rapid and slow cooling conditions, it is found that the residual stress reduces the strength of joint. In the numerical analysis, the intensity of singularity at the corner of interface for a unit load is determined. The intensity of singularity at the corner of the interface is related to the intensities of singularity in the radial direction and on the angle from the side free surface. The critical intensity of singularity for delamination of the interface is obtained by multiplying the force at delamination. Then, the critical intensity of singularity is determined as 168 MPa•mm0.18 regardless of the thickness of silicon film.

Evaluation of the Bonding Strength at the Three-Dimensional Vertex in Silicon-Resin Joints

2009 ◽  
Author(s):  
Hideo Koguchi ◽  
Masato Nakajima
Keyword(s):  
Stress Distribution ◽  
Stress Field ◽  
Boundary Element ◽  
External Force ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Singular Stress ◽  
Singular Stress Field ◽  
Element Method ◽  
Silicon Resin

Portable electric devices such as mobile phone and portable music player become compact and also their performance improves. High density packaging technology such as CSP (Chip Size Package) and Stacked-CSP is needed to realize advanced functions. CSP is a bonded structure composed of materials with different properties. A mismatch of material properties may cause stress singularity at the edge of interface, which lead to the failure of bonding part in structures. Singular stress field in residual thermal stresses occurs in a cooling process after bonding the joints at a high temperature. In the present paper, the strength of interface in CSP consisted of silicon and resin is investigated. Boundary element method and an eigen value analysis based on finite element method are used for evaluating the intensity of singularity of residual thermal stresses at a vertex in a three-dimensional joint. Three-dimensional boundary element program based on the fundamental solution for two-phase isotropic body is used for calculating the stress distribution in the three-dimensional joint. Angular function in the singular stress field at the vertex in the three-dimensional joint is calculated using eigen vector determined from eigen analysis. The strength of bonding at the interface in several silicon-resin specimens with different thickness of resin is investigated analytically and experimentally. Stress singular analysis applying an external force for the joints is firstly carried out. After that, singular stress field for the residual thermal stresses varying material property of resin with temperature is calculated. Combining singular stress fields for the external force and the residual thermal stress yields a final stress distribution for evaluating the strength of interface. A relationship between the external force for delamination in joints and the thickness of resin is derived. Finally, a critical intensity of singularity for delamination between silicon and resin is determined.

Finite Element Simulation of Steel Quench Distortion- Parametric Analysis of Processing Variables

2012 ◽  
Vol 1485 ◽  
pp. 29-34 ◽  
Author(s):  
F. A. García-Pastor ◽  
R.D. López-García ◽  
E. Alfaro-López ◽  
M. J. Castro-Román
Keyword(s):  
Finite Element ◽  
Martensitic Transformation ◽  
Internal Stress ◽  
Thermal Stresses ◽  
Stress Fields ◽  
Leaf Spring ◽  
Internal Stresses ◽  
Processing Temperature ◽  
Fe Model ◽  
Slow Cooling

ABSTRACTSteel quenching from the austenite region is a widely used industrial process to increase strength and hardness through the martensitic transformation. It is well known, however, that it is very likely that macroscopic distortion occurs during the quenching process. This distortion is caused by the rapidly varying internal stress fields, which may change sign between tension and compression several times during quenching. If the maximum internal stress is greater than the yield stress at given processing temperature, plastic deformation will occur and, depending on its magnitude, macroscopic distortion may become apparent.The complex interaction between thermal contraction and the expansion resulting from the martensitic transformation is behind the sign changes in the internal stress fields. Variations in the steel composition and cooling rate will result in a number of different paths, which the internal stresses will follow during processing. Depending on the route followed, the martensitic transformation may hinder the thermal stresses evolution to the point where the stress fields throughout the component may actually be reverted. A different path may support the thermal stresses evolution further increasing their magnitude. The cross-sectional area also affects the internal stresses magnitude, since smaller areas will have further trouble to accommodate stress, thus increasing the distortion. Additionally, the bainitic transformation occurring during relatively slow cooling rates may have an important effect in the final stress field state.A finite-element (FE) model of steel quenching has been developed in the DEFORM 3D simulation environment. This model has taken into account the kinetics of both austenite-bainite and austenite-martensite transformations in a simplified leaf spring geometry. The results are discussed in terms of the optimal processing parameters obtained by the simulation against the limitations in current industrial practice.

Thermal Stress Development in Low Dimensional Silicon Film: An Analytical Approach

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Bekir Sami Yilbas ◽  
R. S. M. Alassar ◽  
Ahmad Y. Al-Dweik
Keyword(s):  
Thermal Stress ◽  
Transport Equation ◽  
Analytical Approach ◽  
Maximum Stress ◽  
Thermal Stresses ◽  
Silicon Film ◽  
Integral Form ◽  
Dimensionless Temperature ◽  
Thermal Excitation ◽  
Low Dimensional

Abstract Thermal excitation of the low dimensional silicon film is introduced and an analytical approach is adopted for the solution of the transport equation. In the analysis, the phonon radiative transport equation is converted into an integral form of the Fredholm equation of the second kind. The analytical approach is extended to include the formulation of thermal stresses for the following cases: (i) stress-free at the edges and (ii) one edge is constrained to have maximum stress while the other edge is set to be stress-free. The analytical and numerical results are evaluated for comparisons. The findings demonstrate that both results are in good agreement. The dimensionless temperature rise at the film mid-thickness becomes sharp for small thickness film. The peak value of thermal stress at the film mid-thickness becomes larger as the film thickness is reduced further. Stress waves generated initially are compressive at the film mid-thickness and they become tensile at both ends of the stress-free film, which becomes more apparent as time increases. Two consecutive compressive and tensile stresses are generated at the mid-thickness of the film as the stress boundary condition is changed to the maximum stress at one edge of the film.

72 COMPARISON OF CRYOPRESERVATION METHODS: SLOW COOLING VERSUS RAPID COOLING BASED ON SPERM VIABILITY OF SPERMATOZOA OBTAINED FROM THE CAUDA EPIDIDYMIS OF ALPACA (VICUGNA PACOS)

2015 ◽  
Vol 27 (1) ◽  
pp. 129
Author(s):  
E. Mellisho ◽  
M. Moina
Keyword(s):  
Vital Staining ◽  
Freezing Process ◽  
Sperm Viability ◽  
Solid Carbon Dioxide ◽  
Slow Cooling ◽  
Rapid Cooling ◽  
Significance Level ◽  
Progressive Motility ◽  
Environment Temperature ◽  
Hypoosmotic Swelling Test

In alpacas, the male has a low reproductive performance due to the small size of the testes, extended period of ejaculation, and low quality of semen. This work had an objective to evaluate 2 methods of cryopreservation on sperm viability of spermatozoa obtained from the cauda epididymis of male alpacas. Testes from 19 male alpacas (>3 years old) were obtained from the slaughterhouse of Huancavelica and transported to the laboratory in isothermal conditions within 3 h of slaughter. The spermatozoa were obtained by slicing the head of the epididymis, diluting in tris-yolk-glycerol at environment temperature, and then refrigerating for 2.5 h at 5°C. The freezing process was carried out by 2 methods, slow cooling and rapid cooling, the results for percentage of progressive motility, vital staining (eosin nigrosin staining), and hypoosmotic swelling test for each method were evaluated. Cryopreservation of spermatozoa by slow cooling was using 0.25-mL straws immediately after the addition of the extenders and sealed with polyvinyl alcohol. The freezing procedure consisted of placing a metallic rack in a polystyrene foam box of 25 × 20 × 15 cm (length × width × height) and pouring LN (–196°C) within the box, keeping the level of LN below the surface of the metallic rack by 6 cm. The straws were placed onto the metallic rack exposing them to the vapors of the LN and closing the box hermetically by 10 min to freeze and then store by immersion in LN. The cryopreservation of spermatozoa by rapid cooling was carried out in pellets of 0.25 mL immediately finishing the addition of the extenders a final concentration of 60 × 106 sperm mL–1. The freezing process consisted of placing the suspension of spermatozoa in holes made on the surface of a block of solid carbon dioxide (dry ice, –79°C) with a micropipette placing aliquots of 0.25 cc quickly and successively, trying to not let the time between the first pellet formed and the last exceed a minute, and then stored by immersion in LN. Semen was thawed at 37°C in hot bath for 1 to 2 min for pellets and 30 s for straws. Percentage of progressive motility, vital staining, and hypoosmotic swelling test were analysed statistically using ANOVA at a significance level of P < 0.05 using the statistical program SAS® 8.0 (Statistic Analysis System, SAS Institute Inc., Cary, NC, USA). There were statistical differences between the 2 methods slow cooling and rapid cooling for percentage of progressive motility (21.7%a v. 36.2%b), vital staining (30.4%a v. 39.7%b), and hypoosmotic swelling test (21.6a v. 19.0a) for the epididymis spermatozoa. We conclude according to the viability parameters for frozen-thawed spermatozoa that the method of rapid cooling (pellets) is a good alternative for cryopreserved spermatozoa from male alpaca epididymis.

Numerical Study of von Mises Stress During Continuous Casting of Multicrystalline Silicon With Large-Size Grains

2013 ◽  
Author(s):  
H. S. Fang ◽  
C. F. Li ◽  
L. L. Zheng ◽  
C. J. Zhao ◽  
Y. S. Xie
Keyword(s):  
Stress Distribution ◽  
Continuous Casting ◽  
Thermal Stresses ◽  
Growth Parameters ◽  
Numerical Study ◽  
Multicrystalline Silicon ◽  
Von Mises Stress ◽  
Casting Technique ◽  
Environment Temperature ◽  
Von Mises

Continuous casting is a promising technique for massive production of multicrystalline silicon (mc-Si). A theoretically advanced study is performed here to investigate the growth of mc-Si with large grain size, which has much higher photoelectric efficiency than normal mc-Si. However, the casting technique results in high thermal stresses due to its inherent features, and limits the photovoltaic applications of mc-Si because of the stress-induced dislocations. For the analysis and optimization of dislocation formation, a computer-aided method has been applied to investigate thermal stress distribution in the growing ingot of continuous casting. The regions of dislocation multiplication are evaluated by comparing von Mises stress to the critical resolved shear stress. It is found that the stress levels are especially high in the regions close to the solid and liquid (S/L) interface, and that the mold wall has a significant effect on the von Mises stress distribution if the billet were attached on the wall. The triple point is better to keep below the mould bottom to avoid its effect during the growth by certain techniques during the industrial production. Parametric studies were further performed to discuss the effects of growth conditions, such as sheath height, environment temperature, and pulling rate on the distribution of the maximum von Mises stress in the billet. The results imply theoretically that multicrystalline silicon with low stress-induced dislocation could be produced by continuous casting with strictly controlled growth parameters.

Electronic Cone Illumination with the Conventional Transmission Electron Microscope

1977 ◽  
Vol 35 ◽  
pp. 72-73
Author(s):  
William Krakow
Keyword(s):  
Electronic Device ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Hollow Cone ◽  
Transmission Electron ◽  
Lissajous Figures ◽  
High Resolution Images ◽  
Imaging Mode ◽  
Diffraction Patterns ◽  
Transmission Microscope

An electronic device has been constructed which manipulates the primary beam in the conventional transmission microscope to illuminate a specimen under a variety of virtual condenser aperture conditions. The device uses the existing tilt coils of the microscope, and modulates the D.C. signals to both x and y tilt directions simultaneously with various waveforms to produce Lissajous figures in the back-focal plane of the objective lens. Electron diffraction patterns can be recorded which reflect the manner in which the direct beam is tilted during exposure of a micrograph. The device has been utilized mainly for the hollow cone imaging mode where the device provides a microscope transfer function without zeros in all spatial directions and has produced high resolution images which are also free from the effect of chromatic aberration. A standard second condenser aperture is employed and the width of the cone annulus is readily controlled by defocusing the second condenser lens.

Resistance Monitor and Control for Vacuum Evaporation of Metals and Carbon

1976 ◽  
Vol 34 ◽  
pp. 572-573
Author(s):  
Russell L. Steere ◽  
Eric F. Erbe ◽  
J. Michael Moseley
Keyword(s):  
Electronic Device ◽  
Point Sources ◽  
High Contrast ◽  
Variable Resistor ◽  
Quality Of Results ◽  
Low Contrast ◽  
Evaporation Source ◽  
And Control ◽  
At Will

We have designed and built an electronic device which compares the resistance of a defined area of vacuum evaporated material with a variable resistor. When the two resistances are matched, the device automatically disconnects the primary side of the substrate transformer and stops further evaporation.This approach to controlled evaporation in conjunction with the modified guns and evaporation source permits reliably reproducible multiple Pt shadow films from a single Pt wrapped carbon point source. The reproducibility from consecutive C point sources is also reliable. Furthermore, the device we have developed permits us to select a predetermined resistance so that low contrast high-resolution shadows, heavy high contrast shadows, or any grade in between can be selected at will. The reproducibility and quality of results are demonstrated in Figures 1-4 which represent evaporations at various settings of the variable resistor.

Digital image processing methods applied to the study of annealing time on semiconductor-metal eutectic composites

1988 ◽  
Vol 46 ◽  
pp. 848-849
Author(s):  
J. Hefter
Keyword(s):  
Image Processing ◽  
Digital Image Processing ◽  
Digital Image ◽  
Electronic Device ◽  
Processing System ◽  
Average Diameter ◽  
Eutectic Solidification ◽  
Metal Silicide ◽  
The Matrix ◽  
Microscopic Studies

Semiconductor-metal composites, formed by the eutectic solidification of silicon and a metal silicide have been under investigation for some time for a number of electronic device applications. This composite system is comprised of a silicon matrix containing extended metal-silicide rod-shaped structures aligned in parallel throughout the material. The average diameter of such a rod in a typical system is about 1 μm. Thus, characterization of the rod morphology by electron microscope methods is necessitated.The types of morphometric information that may be obtained from such microscopic studies coupled with image processing are (i) the area fraction of rods in the matrix, (ii) the average rod diameter, (iii) an average circularity (roundness), and (iv) the number density (Nd;rods/cm2). To acquire electron images of these materials, a digital image processing system (Tracor Northern 5500/5600) attached to a JEOL JXA-840 analytical SEM has been used.

Deformation at interfaces of Ti-6Al-4V/SiC fiber composites

1992 ◽  
Vol 50 (1) ◽  
pp. 158-159
Author(s):  
Warren J. Moberly ◽  
Daniel B. Miracle ◽  
S. Krishnamurthy
Keyword(s):  
Thermal Stresses ◽  
Load Transfer ◽  
Coefficient Of Thermal Expansion ◽  
Hot Isostatic Pressing ◽  
Matrix Composites ◽  
Ongoing Research ◽  
Aerospace Applications ◽  
Sic Fiber ◽  
The Matrix ◽  
Intermetallic Matrix Composites

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.

Sign in / Sign up

Export Citation Format

Share Document