Evaluation of Interface Strength at the 3D-Corner in Si-Resin Joint Considering Residual Thermal Stresses

Author(s):  
Hideo Koguchi ◽  
Takashi Taniguchi

A mismatch of different material properties in joints may cause stress singularities, which lead to the failure of the bonding part. It is very important to reveal a stress singularity field for evaluating the strength of interface in three-dimensional joints. Furthermore, thermal residual stresses occur in a cooling process after bonding the joints, and the stress singularity for thermal stress also occurs. In the present study, a boundary element method and an eigen value analysis based on finite element method are used for evaluating the intensity of stress singularity. Three-dimensional boundary element program based on the fundamental solution for two-phase isotropic body is used. The strength of interface in two kinds of Si-resin specimen with different bonding area is investigated analytically and experimentally. Stress singularity analysis applying an external force for debonding the joints is firstly carried out. After that, stress singularity field for the residual stresses varying material property in resin with temperature is determined. Combining the stress singularity fields for the mechanical force and the residual thermal stress yields a final stress distribution for evaluating the strength of interface. Finally, a relationship of force for delamination in joints with different bonding areas is derived.

1990 ◽  
Vol 25 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Y Ochiai ◽  
R Ishida ◽  
T Sekiya

A numerical method to analyse unsteady thermal stresses in three-dimensional problems is proposed. It is shown that three-dimensional unsteady thermal stress problems can be easily solved without the volume integral by means of the thermoelastic displacement potential and the boundary element method. It is also shown that the time integral can be easily carried out analytically. In order to investigate the accuracy of this method, unsteady thermal stress distributions for a sphere and a circular cylinder are obtained. As a numerical example for which it is difficult to obtain the analytical solution, thermal displacements and surface stress distributions for a torus are obtained.


Author(s):  
Hideo Koguchi ◽  
Kazuhisa Hoshi

Portable electric devices such as mobile phone and portable music player become compact and improve their performance. High-density packaging technology such as CSP (Chip Size Package) and Stacked-CSP is used for improving the performance of devices. CSP has a bonded structure composed of materials with different properties. A mismatch of material properties may cause stress singularity, which lead to the failure of bonding part in structures. In the present paper, stress analysis using boundary element method and an eigenvalue analysis using finite element method are used for evaluating the intensity of singularity at a vertex in three-dimensional joints. Three-dimensional boundary element program based on the fundamental solution for two-phase isotropic materials is used for calculating the stress distribution in a 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 the eigenvalue analysis. The joining strength of interface in several kinds of sillicon-resin specimen with different triangular bonding areas is investigated analytically and experimentally. Experiment for debonding the interface in the joints is firstly carried out. Stress singularity analysis for the three-dimensional joints subjected to an external force for debonding the joints is secondly conducted. Combining results of the experiment and the analysis yields a final stress distribution for evaluating the strength of interface. Finally, a relationship of force for delamination in joints with different bonding areas is derived, and a critical value of the 3D intensity of singularity is determined.


2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Hideo Koguchi ◽  
Kazuhisa Hoshi

Portable electric devices such as mobile phones and portable music players have become compact and improved their performance. High-density packaging technology such as chip size package (CSP) and stacked-CSP is used for improving the performance of devices. CSP has a bonded structure composed of materials with different properties. A mismatch of material properties may cause a stress singularity, which leads to the failure of the bonding part in structures. In the present paper, stress analysis using the boundary element method and an eigenvalue analysis using the finite element method are used for evaluating the intensity of a singularity at a vertex in three-dimensional joints. A three-dimensional boundary element program based on the fundamental solution for two-phase isotropic materials is used for calculating the stress distribution in a three-dimensional joint. Angular function in the singular stress field at the vertex in the three-dimensional joint is calculated using an eigenvector determined from the eigenvalue analysis. The joining strength of interface in several kinds of sillicon-resin specimen with different triangular bonding areas is investigated analytically and experimentally. An experiment for debonding the interface in the joints is firstly carried out. Stress singularity analysis for the three-dimensional joints subjected to an external force for debonding the joints is secondly conducted. Combining results of the experiment and the analysis yields a final stress distribution for evaluating the strength of interface. Finally, a relationship of force for delamination in joints with different bonding areas is derived, and a critical value of the 3D intensity of the singularity is determined.


Author(s):  
Hideo Koguchi ◽  
Masato Nakajima

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.


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