Viscoelastic Warpage Analysis of Surface Mount Package

2001 ◽  
Vol 123 (2) ◽  
pp. 101-104 ◽  
Author(s):  
Kiyoshi Miyake ◽  
Tsukasa Yoshida ◽  
Hyung Gil Baik ◽  
Sang Wook Park
Keyword(s):  
Finite Element ◽  
Solder Joint ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Shell Element ◽  
Critical Issue ◽  
Thickness Ratio ◽  
Surface Mount ◽  
Joint Connection ◽  
Saddle Shape

The reduction of the warpage of LSI package is a critical issue to ensure good solder joint connection in surface mount. In this study, different combinations of finite element and calculating methods were used to investigate the best method for predicting the thin small outline packages (TSOP) warpage. The results indicate that viscoelastic-GK calculation with relaxation of shear modulus and of bulk modulus using the multilayer shell element is the most appropriate method for predicting the warpage. All calculations confirm that a compound thickness ratio of 1.2 results in minimal warpage for a large chip TSOP. In this case, the warpage is reduced to near zero and the compound properties have little influence on warpage. However, for a small chip TSOP, a compound thickness ratio of 2.0–2.9 reduces the warpage. The warpage of small chip TSOP shows a severe saddle shape. The ratio and the magnitude of warpage depend on the compound properties. Also, the elastic method may result in a false simulation.

Stress Analysis of Surface-Mount Interconnections Due to Vibrational Loading

1997 ◽  
Vol 119 (3) ◽  
pp. 183-188 ◽  
Author(s):  
K. Darbha ◽  
S. Ling ◽  
A. Dasgupta
Keyword(s):  
Finite Element ◽  
Solder Joint ◽  
Stress Analysis ◽  
Solder Joints ◽  
Test Time ◽  
Clear Understanding ◽  
Local Curvature ◽  
Surface Mount ◽  
Quantitative Models ◽  
Vibrational Loading

Recently, accelerated testing of surface mount interconnects under combined temperature and vibration environments has been recognized to be a necessary activity to ensure enhanced test-time compression. Successful use of vibration stresses requires a clear understanding of the correlation between vibrational damage and thermomechanical damage in surface mount solder joints. Hence, fatigue due to vibrational loading is important and accurate quantitative models are required to model effects due to vibrational fatigue. The proposed analysis in this paper contributes towards development of such quantitative models. This paper presents an approximate method to analyze stresses in surface mount solder joints subjected to vibration loading, using a generalized multidomain Rayleigh-Ritz approach (Ling and Dasgupta, 1995). The advantage of this approach is in its computational efficiency, compared to general-purpose finite element methods. Ling developed this approach in the context of thermomechanical stress analysis of solder joints. In this paper, the technique is modified and adapted for analyzing stresses caused by out-of-plane flexural dynamic modes of the printed wiring boards (PWBs). The analysis uses a two-step procedure where the local PWB curvatures are first estimated and the resulting deformations in the solder interconnect are then determined. The input boundary conditions for the first step are the bending moments in the PWB due to random vibrations. The stiffness of the interconnect assembly is then predicted using an energy method and curved-beam analysis. The bending moment and the computed stiffness of the interconnect assembly are then used to predict the local curvature of the PWB under any given surface-mount component by using an eigenfunction technique developed by Suhir (Suhir, 1988). In the second step of the analysis, the local curvature of the PWB is used as a boundary condition to predict the state of deformations, stresses, and strains in the solder joint using a modified version of the multidomain Rayleigh-Ritz approach. The overall method is applied to a specific example (J-lead solder joint) for illustrative purposes, and compared to finite element predictions for validation.

Estimating the Vibration Fatigue Life of Quad Leaded Surface Mount Components

1993 ◽  
Vol 115 (2) ◽  
pp. 195-200 ◽  
Author(s):  
D. B. Barker ◽  
Y. S. Chen ◽  
A. Dasgupta
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Solder Joint ◽  
Finite Element Modeling ◽  
Stress Analysis ◽  
Empirical Equation ◽  
Solder Joint Reliability ◽  
Surface Mount ◽  
Joint Reliability ◽  
Vibration Fatigue

This paper discusses the assumptions and details of the fatigue life calculations required to predict the fatigue life of quad leaded surface mount components operating in a vibration environment. A simple approximate stress analysis is presented that does not require complex finite element modeling, nor does it reduce the problem to a simple empirical equation or rule of thumb. The goal of the new method is to make PWB vibration solder joint reliability information available to the designer as early as possible and in an easily understood and implemented manner.

Improved Analytical and Semi-Analytical Durability Models (Constrained Models) for Various Surface-Mount Configurations

2002 ◽  
Author(s):  
Pradeep Sharma ◽  
James Loman
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Deformation Process ◽  
Analytical Models ◽  
Surface Mount ◽  
Constrained Models ◽  
Constraint Approach ◽  
Finite Element Calibration

Several analytical and semi-analytical models to predict solder joint durability under thermal cycling loadings have been proposed. In general, these models are overtly conservative often requiring extensive experimental and/or finite element calibration. We present, based on the physics of the deformation process, a direct approach to improve these classes of model by resolving one of the major causes of conservatism. Our contribution is applicable to virtually all known surface mount configurations. The improved models (henceforth termed as constraint models) retain the simplicity of use of the existing ones. The efficacy of constraint approach is demonstrated on leadless resistors and comparisons are made with existing models and experimental data.

Effect of SMC Lead Dimensional Variabilities on Lead Compliance and Solder Joint Fatigue Life

1992 ◽  
Vol 114 (2) ◽  
pp. 177-184 ◽  
Author(s):  
D. B. Barker ◽  
I. Sharif ◽  
A. Dasgupta ◽  
M. G. Pecht
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Solder Joint ◽  
Three Dimensional ◽  
Finite Element Analyses ◽  
Surface Mount ◽  
Stiffness Matrices ◽  
Solder Joint Fatigue ◽  
Parametric Analyses ◽  
Three Dimensional Finite Element

Lead compliance is a critical parameter in optimal design and interconnection reliability of surface mount leaded components. The cyclic force transmitted to the solder joint in surface mount leaded components is controlled in part by the lead compliance. In this paper a methodology is presented for the computation of lead stiffness and the prediction of fatigue life of the leaded surface mount components. Three-dimensional finite element analyses have been performed to obtain the 12 × 12 stiffness matrices for both the PQFP gullwing and PLCC J leads and solder joints. These stiffnesses are then used in predictive fatigue life equations to estimate the fatigue life. The stiffness matrices and diagonal lead stiffnesses form the basis for identifying more failure resistant packages. Variabilities in lead and package dimensions provided by different vendors, manufacturing to JEDEC standards, are identified and their adverse effects on solder joint fatigue life are studied with the help of finite element parametric analyses. Eighty different finite element analyses are performed to study the effect of change in lead length, height, width and thickness on the lead stiffness and solder joint fatigue life for both the PQFP and PLCC attachments. Finally recommendations are made in order to obtain a better control on component fatigue life.

scholarly journals Generalization of intrinsic ductile-to-brittle criteria by Pugh and Pettifor for materials with a cubic crystal structure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
O. N. Senkov ◽  
D. B. Miracle
Keyword(s):  
Crystal Structure ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Single Crystal ◽  
Elastic Constants ◽  
Mechanical Analysis ◽  
Quantum Mechanical ◽  
Modulus Ratio ◽  
Cubic Crystal ◽  
The Difference

AbstractTwo classical criteria, by Pugh and Pettifor, have been widely used by metallurgists to predict whether a material will be brittle or ductile. A phenomenological correlation by Pugh between metal brittleness and its shear modulus to bulk modulus ratio was established more than 60 years ago. Nearly four decades later Pettifor conducted a quantum mechanical analysis of bond hybridization in a series of intermetallics and derived a separate ductility criterion based on the difference between two single-crystal elastic constants, C12–C44. In this paper, we discover the link between these two criteria and show that they are identical for materials with cubic crystal structures.

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