Minimization of the Local Residual Stress in 3D Flip Chip Structures by Optimizing the Mechanical Properties of Electroplated Materials and the Alignment Structure of TSVs and Fine Bumps

2011 ◽  
Author(s):  
Kohta Nakahira ◽  
Hironori Tago ◽  
Fumiaki Endo ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Thermal Deformation ◽  
Flip Chip ◽  
Flexural Rigidity ◽  
Three Dimensional ◽  
Strain Gauges ◽  
Copper Interconnection ◽  
Induced Stress ◽  
Alignment Structure

Since the thickness of the stacked silicon chips in 3D integration has been thinned to less than 100 μm, the local thermal deformation of the chips has increased drastically because of the decrease of the flexural rigidity of the thinned chips. The clear periodic thermal deformation and thus, the thermal residual stress distribution appears in the stacked chips due to the periodic alignment of metallic bumps, and they deteriorate the reliability of products. In this paper, the dominant structural factors of the local residual stress in a silicon chip are discussed quantitatively based on the results of a three-dimensional finite element analysis and the measurement of the local residual stress in a chip using stress sensor chips. The piezoresistive strain gauges were embedded in the sensor chips. The length of each gauge was 2 μm, and an unit cell consisted of 4 gauges with different crystallographic directions. This alignment of strain gauges enables to measure the tensor component of three-dimensional stress fields separately. Test flip chip substrates were made by silicon chip on which the area-arrayed tin/copper bumps were electroplated. The width of a bump was fixed at 200 μm, and the bump pitch was varied from 400 μm to 1000 μm. The thickness of the copper layer was about 40 μm and that of tin layer was about 10 μm. This tin layer was used for the rigid joint formation by alloying with copper interconnection formed on a stress sensing chip. The measured amplitude of the residual stress increased from about 30 MPa to 250 MPa depending on the combination of materials such as bump, underfill, and interconnections. It was confirmed that both the material constant of underfill and the alignment structure of fine bumps are the dominant factors of the local deformation and stress of a silicon chip mounted on area-arrayed metallic bumps. It was also confirmed experimentally that both the hound’s-tooth alignment between a TSV (Through Silicon Via) and a bump and control of mechanical properties of electroplated copper thin films used for the TSV and bump is indispensable in order to minimize the packaging-induced stress in the three-dimensionally mounted chips. This test chip is very effective for evaluating the packaging-process induced stress in 3D stacked chips quantitatively.

Minimization of the Local Residual Stress in 3D Flip Chip Structures by Optimizing the Mechanical Properties of Electroplated Materials and the Alignment Structure of TSVs and Fine Bumps

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Kota Nakahira ◽  
Hironori Tago ◽  
Fumiaki Endo ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Thermal Deformation ◽  
Flip Chip ◽  
Flexural Rigidity ◽  
Three Dimensional ◽  
Strain Gauges ◽  
Copper Interconnection ◽  
Induced Stress ◽  
Alignment Structure

Since the thickness of stacked silicon chips in 3D integration has been thinned to less than 100 μm, the local thermal deformation of the chips has increased drastically because of the decrease of the flexural rigidity of the thinned chips. The clear periodic thermal deformation and thus, the local distribution of thermal residual stress appears in the stacked chips due to the periodic alignment of metallic bumps, and they sometimes deteriorate mechanical and electrical reliability of electronic products. In this paper, the dominant structural factors of the local residual stress in a silicon chip are investigated quantitatively based on the results of a three-dimensional finite element analysis and the measurement of the local residual stress in a chip using stress sensor chips. The piezoresistive strain gauges were embedded in the sensor chips. The length of each gauge was 2 μm, and an unit cell consisted of four gauges with different crystallographic directions. This alignment of the strain gauges enables us to measure the tensor component of three-dimensional stress fields separately. Test flip chip substrates were made of silicon chip on which the area-arrayed tin/copper bumps were electroplated. The width of a bump was fixed at 200 μm, and the bump pitch was varied from 400 μm to 1000 μm. The thickness of the copper bump was about 40 μm and that of tin layer was about 10 μm. This tin layer was used for the formation of rigid joint by alloying it with copper interconnection formed on a stress sensing chip. The measured amplitude of the residual stress increased from about 30 MPa to 250 MPa depending on the combination of materials such as bump, underfill, and interconnections. It was confirmed that both the material constant of underfill and the alignment structure of fine bumps are the dominant factors of the local deformation and stress of a silicon chip mounted on area-arrayed metallic bumps. It was also confirmed that not only the control of mechanical properties of electroplated copper thin films, but also the hound’s-tooth alignment of a through silicon via and a bump are indispensable for minimizing the packaging-induced stress in the three-dimensionally mounted chips. This test chip is very effective for evaluating the packaging-process-induced stress in 3D stacked chips quantitatively.

scholarly journals The visceral pericardium: macromolecular structure and contribution to passive mechanical properties of the left ventricle

2007 ◽  
Vol 293 (6) ◽  
pp. H3379-H3387 ◽  
Author(s):  
Paul D. Jöbsis ◽  
Hiroshi Ashikaga ◽  
Han Wen ◽  
Emily C. Rothstein ◽  
Keith A. Horvath ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Ex Vivo ◽  
Second Harmonic ◽  
Three Dimensional ◽  
Left Ventricular ◽  
Opening Angle ◽  
Passive Stiffness ◽  
Photon Excitation ◽  
Before And After

Much attention has been focused on the passive mechanical properties of the myocardium, which determines left ventricular (LV) diastolic mechanics, but the significance of the visceral pericardium (VP) has not been extensively studied. A unique en face three-dimensional volumetric view of the porcine VP was obtained using two-photon excitation fluorescence to detect elastin and backscattered second harmonic generation to detect collagen, in addition to standard light microscopy with histological staining. Below a layer of mesothelial cells, collagen and elastin fibers, extending several millimeters, form several distinct layers. The configuration of the collagen and elastin layers as well as the location of the VP at the epicardium providing a geometric advantage led to the hypothesis that VP mechanical properties play a role in the residual stress and passive stiffness of the heart. The removal of the VP by blunt dissection from porcine LV slices changed the opening angle from 53.3 ± 10.3 to 27.3 ± 5.7° (means ± SD, P < 0.05, n = 4). In four porcine hearts where the VP was surgically disrupted, a significant decrease in opening angle was found (35.5 ± 4.0°) as well as a rightward shift in the ex vivo pressure-volume relationship before and after disruption and a decrease in LV passive stiffness at lower LV volumes ( P < 0.05). These data demonstrate the significant and previously unreported role that the VP plays in the residual stress and passive stiffness of the heart. Alterations in this layer may occur in various disease states that effect diastolic function.

Three-Dimensional Numerical Simulation of Temperature Field and Force Field of T-Type Turbe during Welding

2013 ◽  
Vol 690-693 ◽  
pp. 2659-2663
Author(s):  
Jian Ping Zhou ◽  
Xiang Feng Zhang ◽  
Hong Sheng Liu ◽  
Jun Yi Gao ◽  
Yan Xu
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Temperature Field ◽  
Three Dimensional ◽  
Welding Process ◽  
Three Dimension ◽  
Analysis Software ◽  
Element Analysis ◽  
Cool Process ◽  
Type Tube

Residual stress affect the lifetime of weldments directly. Temperature Generated from the welding process is the major reason that influences the microstructure and mechanical properties of the metal weldments. Therefore it is necessary to simulate the temperature field for optimizing the structure of weldments. In this work the three-dimension finite element analysis software SYSWELS was used to simulate T-type tube, and carried on a detailed analysis of temperature field and residual stress in cool process of weld.

Three-Dimensional Stress Singularity Analysis Around the Solder Joints in Electronic Packaging Using Eigen Analysis

2003 ◽  
Author(s):  
Monchai Prukvilailert ◽  
Hideo Koguchi
Keyword(s):  
Mechanical Properties ◽  
Electronic Packaging ◽  
Flip Chip ◽  
Solder Bump ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Dissimilar Materials ◽  
Singularity Analysis ◽  
Contact Angles ◽  
Eigen Analysis

Electronic packaging has several kinds of joint structures of metal, ceramic and polymer. It is well known that the stress singularity occurs at the vertex of joint where the dissimilar materials are bonded together. In this paper, the model in the first analysis is an electronic package using surface mount technology (SMT), the order of stress singularity is investigated, when the mechanical properties of solder, adhesive and resin vary for several values of contact angles between the solder with the chip and with a Cu land. Furthermore, the model in the second analysis is a Flip-Chip-on-Board packaging (FCOB), in which the order of stress singularity at the solder bump is investigated varying the mechanical properties of solder, underfill and the contact angle between the solder bump with a Cu track. After that, the displacement and stress fields for several values of the order of stress singularity are calculated by solving an eigen equation.

Mechanical Stress Monitoring Sensor for 3-D Module During Manufacturing and Operation

2017 ◽  
Author(s):  
Koki Isobe ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Crystalline Silicon ◽  
Three Dimensional ◽  
Stress Monitoring ◽  
Impact Stress ◽  
Total Structure ◽  
Periodic Stress ◽  
The Impact ◽  
Packaging Module

In three-dimensional packaging module which have been used in electronic equipment, the size of partial interconnections and total structure have been continuously miniaturized for improving the performance of the products. Due to the fluctuation of the mechanical properties of the component materials and the drop impact towards the fragile modules during manufacturing and operation, the final residual stress varies easily in a chip of the 3-D structure. Both the static and dynamic changes of the stress distribution induce the variation of the performance of electronic devices and the degradation of their long-term reliability. It is, therefore, important to control and optimize the residual stress quantitatively. In this study, a stress sensor which can monitor the change of the local residual stress in 3-D module was developed by applying the piezoresistance effect of single-crystalline silicon. The sensor was embedded in a silicon chip, and it can measure the periodic stress in a silicon chip assembled by area-arrayed bump structure. The impact stress during the manufacturing process was successfully monitored by using this sensor. It was also confirmed that the effective amplitude of the impact stress varies drastically depending on the mechanical properties of the stacked thin films.

A Study on the Thermal Deformation and the Mechanical Properties due to Curing Process of the Encapsulation Resin

2011 ◽  
Author(s):  
Hiroyuki Sato ◽  
Qiang Yu ◽  
Ryusuke Sone
Keyword(s):  
Mechanical Properties ◽  
Thermal Deformation ◽  
Flexural Rigidity ◽  
Correlation Method ◽  
Practical Method ◽  
Curing Temperature ◽  
Image Correlation ◽  
Bending Test ◽  
Curing Process ◽  
Curing Shrinkage

Since the flexural rigidity of thin semiconductor package becomes much lower than normal components, the warpage of the component becomes a much more important issue to evaluate the reliability. In this study the author propose a new practical method to measure the real time curing deformation and the elastic modulus of the resin during the whole curing process. The thermal deformation of the resin under curing was measured by using the optical digital image correlation method. Next, to examine the mechanical properties of the resin, the liquid resin was poured into an aluminum frame with thin sole, and the bending rigid of the aluminum frame was measured by the three points bending test every minutes at the curing temperature of the resin. Based upon the experimented result, the warpage of a package caused of curing shrinkage was simulated.

scholarly journals Three-Dimensional Finite Element Study on Lithium Diffusion and Intercalation-Induced Stress in Polycrystalline LiCoO2 Using Anisotropic Material Properties

2018 ◽  
Vol 16 (2) ◽  
Author(s):  
Linmin Wu ◽  
Jing Zhang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Phase Field ◽  
Three Dimensional ◽  
Stress Generation ◽  
Diffusion Pathway ◽  
Finite Element Study ◽  
Induced Stress ◽  
Anisotropic Mechanical Properties ◽  
Element Study

In this study, lithium (Li) intercalation-induced stress of LiCoO2 with anisotropic properties using three-dimensional (3D) microstructures has been studied systematically. Phase field method was employed to generate LiCoO2 polycrystals with varying grain sizes. Li diffusion and stresses inside the polycrystalline microstructure with different grain size, grain orientation, and grain boundary diffusivity were investigated using finite element method. The results show that the anisotropic mechanical properties and Li concentration-dependent volume expansion coefficient have a very small influence on the Li chemical diffusion coefficients. The low partial molar volume of LiCoO2 leads to this phenomenon. The anisotropic mechanical properties have a large influence on the magnitude of stress generation. Since the Young's modulus of LiCoO2 along the diffusion pathway (a–b axis) is higher than that along c–axis, the Li concentration gradient is larger along the diffusion pathway. Thus, for the same intercalation-induced strain, the stress generation will be higher (∼40%) than that with isotropic mechanical properties as discussed in our previous study (Wu, L., Zhang, Y., Jung, Y.-G., and Zhang, J., 2015, “Three-Dimensional Phase Field Based Finite Element Study on Li Intercalation-Induced Stress in Polycrystalline LiCoO2,” J. Power Sources, 299, pp. 57–65). This work demonstrates the importance to include anisotropic property in the model.

scholarly journals STUDY ON ADJUSTABLE CONNECTOR OF RECIPROCAL FRAME

2021 ◽  
Vol 30 (2) ◽  
Author(s):  
Lin Qi ◽  
Zifei Li ◽  
Hui Pan ◽  
Lingtong Li ◽  
Xin Huang
Keyword(s):  
Mechanical Properties ◽  
Flexural Rigidity ◽  
Plastic Hinge ◽  
Three Dimensional ◽  
High Strength ◽  
Test Model ◽  
Hollow Section ◽  
Reciprocal Frames ◽  
Scale Test ◽  
Circular Hollow Section

In this paper, we design an adjustable connector of reciprocal frame, and a three-dimensional solid model of this connector with Circular Hollow Section has been created in the FEM software Abaqus CAE to study its mechanical properties. When the plastic hinge is formed at the end of the Circular Hollow Section, the connector is still in an elastic state. It is concluded that the adjustable connector of reciprocal frame has high strength and rigidity, realizing the goal for designing higher connector strength over Circular Hollow Section strength. Then parametric analysis is used to analyse the influence of the connector about each part on the mechanical properties, and the flexural rigidity of the connector has been derived. A three-dimensional wire model of reciprocal frames has been created in the FEM software Abaqus CAE, and a full-scale test model of the structure is designed. The numerical simulation results agree well with the test results. It is verified that the reliability of the modeling method and the accuracy of the connector mechanical model.

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