scholarly journals Research on Reliability of Nano Silver Tin Pulp in Flip Chip Solder Joint

2020 ◽  
Author(s):  
Hui Yang ◽  
Jihui Wu
Keyword(s):  
Fatigue Life ◽  
Solder Joint ◽  
Flip Chip ◽  
Equivalent Plastic Strain ◽  
Inelastic Strain ◽  
Second Phase ◽  
Strengthening Effect ◽  
Silver Paste ◽  
Nano Silver ◽  
Life Model

Abstract In order to improve the interconnect properties of nano-silver solders, we have developed a new tin-doped nano-silver paste (referred to as silver tin paste). The hard brittle phase Ag3Sn formed by the soldering of the silver tin paste acts as a second phase strengthening effect, which significantly improves the shear strength of the solder joint and has the potential to be widely used in the power electronics packaging industry. In this paper, the viscoplastic and elastic composite model is used to simulate the inelastic deformation behavior of flip chip nano silver tin solder joint under uniaxial shear load. The simulated stress-strain response curve agrees well with the experimentally measured data. The finite element method is used to simulate the interconnection state of flip chip solder joints under thermal cycling conditions. It can be seen that the inelastic strain of the silver tin solder joint has increased, and it can be inferred that as this strain increases further, the chip connection will be broken. The fatigue life of silver tin paste is predicted by the creep fatigue life model. Compared with the pure nano silver paste, the equivalent plastic strain of the silver tin paste is reduced and the fatigue life is significantly improved. It is indicated that the solder joint reliability of nano silver paste can be improved by tin doping. The analysis results provide reference data for the development of new nano solder.

Precision Evaluation for Thermal Fatigue Life of Power Module Using Coupled Electrical-Thermal-Structural Analysis

2011 ◽  
Author(s):  
Tomohiro Takahashi ◽  
Qiang Yu ◽  
Masahiro Kobayashi
Keyword(s):  
Fatigue Life ◽  
Temperature Distribution ◽  
Solder Joint ◽  
Thermal Fatigue ◽  
Thermal Structure ◽  
Inelastic Strain ◽  
Power Module ◽  
Thermal Fatigue Life ◽  
Power Cycling ◽  
Precision Evaluation

For power module, the reliability evaluation of thermal fatigue life by power cycling has been prioritized as an important concern. Since in power cycling produces there exists non-uniform temperature distribution in the power module, coupled thermal-structure analysis is required to evaluate thermal fatigue mechanism. The thermal expansion difference between a Si chip and a substrate causes thermal fatigue. In this study, thermal fatigue life of solder joints on power module was evaluated. The finite element method (FEM) was used to evaluate temperature distribution induced by joule heating. Higher temperature appears below the Al wire because the electric current flows through the bonding Al wire. Coupled thermal-structure analysis is also required to evaluate the inelastic strain distribution. The damage of each part of solder joint can be calculated from equivalent inelastic strain range and crack propagation was simulated by deleting damaged elements step by step. The initial cracks were caused below the bonding Al wire and propagated concentrically under power cycling. There is the difference from environmental thermal cycling where the crack initiated at the edge of solder layer. In addition, in order to accurately evaluate the thermal fatigue life, the factors affecting the thermal fatigue life of solder joint where verified using coupled electrical-thermal-structural analysis. Then, the relation between the thermal fatigue life of solder joint and each factor is clarified. The precision evaluation for the thermal fatigue life of power module is improved.

scholarly journals Prediction of mechanical properties and fatigue life of nano silver paste in chip interconnection

2020 ◽  
Author(s):  
Hui YANG ◽  
Jihui Wu
Keyword(s):  
Fatigue Life ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Solder Joints ◽  
Stress And Strain ◽  
Nano Silver ◽  
Finite Element Software ◽  
Flip Chips ◽  
Empirical Correction ◽  
Prediction Of Mechanical Properties

Abstract The simulation of nano-silver solder joints in flip-chips is performed by the finite element software ANSYS, and the stress-strain distribution results of the solder joints are displayed. In this simulation, the solder joints use Anand viscoplastic constitutive model, which can reasonably simulate the stress and strain of solder joints under thermal cycling load. At the same time this model has been embedded in ANSYS software, so it is more convenient to use. The final simulation results show that the areas where the maximum stresses and strains occur at the solder joints are mostly distributed in the contact areas between the solder joints and the copper pillars and at the solder joints. During the entire thermal cycling load process, the area where the maximum change in stress and strain occurs is always at the solder joint, and when the temperature changes, the temperature at the solder joint changes significantly. Based on comprehensive analysis, the relevant empirical correction calculation equation is used to calculate and predict the thermal fatigue life of nano-silver solder joints. The analysis results provide a reference for the application of nano-silver solder in the electronic packaging industry.

A new creep–fatigue life model of lead-free solder joint

2015 ◽  
Vol 55 (7) ◽  
pp. 1097-1100 ◽  
Author(s):  
Yongxin Zhu ◽  
Xiaoyan Li ◽  
Chao Wang ◽  
Ruiting Gao
Keyword(s):  
Fatigue Life ◽  
Solder Joint ◽  
Lead Free ◽  
Lead Free Solder ◽  
Creep Fatigue ◽  
Life Model ◽  
Free Solder

Fatigue life model of solder joint under multi-physics conditions based on transfer entropy

2017 ◽  
Vol 47 (5) ◽  
pp. 484-494
Author(s):  
Wei TANG ◽  
Bo JING ◽  
ZengJin SHENG ◽  
JiaXing HU
Keyword(s):  
Fatigue Life ◽  
Solder Joint ◽  
Transfer Entropy ◽  
Life Model

Effect of Board-Level Reflow on Adhesion Between Lead-Free Solder and Underfill in Flip-Chip BGA Packages

2007 ◽  
Author(s):  
Zhenming Tang ◽  
Seungbae Park ◽  
H. C. John Lee ◽  
Soonwan Chung
Keyword(s):  
Fatigue Life ◽  
Flip Chip ◽  
Structural Integrity ◽  
Fea Model ◽  
Bga Packages ◽  
Life Model ◽  
Strong Adhesion ◽  
The Difference ◽  
Free Solder ◽  
Perfect Adhesion

The change in solder/underfill adhesion and its effect on fatigue life were investigated for Pb-free solder joints for which, during the reflow process, the solder has melted and resolidified inside the underfill cavities. The change in interfacial adhesion was simulated and its strength compared using button shear test. Surprisingly, the difference was found to be only about 11%. Suspecting the validity of the result, the study was extended to further investigate the adhesion effect on fatigue life under thermal cycles. The effect was assessed analytically using FEA model. Energy-based Darveaux’s fatigue life model [1] is used to calculate solder fatigue life under two extreme conditions: perfect adhesion (without delamination or void between underfill and solder) and non adhesion. The failure parameter, accumulated plastic work per cycle for non adhesion was significantly less than that for perfect adhesion case suggesting adverse effect of strong adhesion to the enhancement of structural integrity. In this simulation, the room temperature was taken as the stress free state.

Deterministic and Statistical Reliability of Surface Mount Components

2002 ◽  
Author(s):  
Zhengfang Qian ◽  
Xiaohua Wu ◽  
Joe Tomase
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Solder Joint ◽  
Crack Propagation ◽  
Temperature Profile ◽  
Failure Rate ◽  
Inelastic Strain ◽  
Reliability Prediction ◽  
Joint Geometry ◽  
Statistical Reliability

This paper is to investigate both deterministic and statistical aspects of thermal reliability of solder joints of surface mount leadless components (SMLCs). The emphasis is on bridging deterministic with statistical reliability prediction. A reliable methodology has been established to predict the failure rate at accelerated life tests (ALTs) and field failed rate in terms of key statistical parameters of design, environmental condition, and material selection due to the uncertainty from the component manufacturing/assembly, temperature profile of ALTs and field environmental conditions, and material property. Analytical equations and solutions of inelastic strain range and fatigue life for simplified joint geometry have been developed from deterministic approach. They are furthermore utilized to obtain the failure functions of thermal fatigue caused by both crack initiation and crack propagation from multivariable distributions. First Order Reliability Model (FORM) has been extended by combining Taylor series in technique with central limit theorem (CLT). An important outcome is that the statistical fatigue life is a lognormal distribution in which its parameters can be analytically evaluated by the approximate method with satisfactory accuracy for small COVs (COV=mean/deviation) of random variables (RVs). Specifically, SMLCs have been investigated on inelastic strain distribution, fatigue life distribution, failure and reliability functions, and failure rate prediction based on the statistical distributions of the solder joint height, solder paste size, temperature profile, and the experimental property of the eutectic solder alloy. Moreover, the component failure under two failure modes, i.e., both crack initiation and crack propagation, has been performed to illustrate the significance of failure criteria selection and address the data collection in field. Additionally, the simulation of realistic solder joint geometry and damage-based failure processes will be also presented. The developed methodology can be directly used for the board-level reliability prediction of advanced electronic packages such as BGAs, CSPs, QFPs, and Flip-chips.

Interconnect Design and Thermal Stress/Strain Analysis of Flip Chip Packaging

2006 ◽  
Vol 326-328 ◽  
pp. 521-524
Author(s):  
Chang Ming Liu ◽  
Chang Chun Lee ◽  
Hsiao Tung Ku ◽  
Chien Chia Chiu ◽  
Kuo Ning Chiang
Keyword(s):  
Solder Joint ◽  
Electronic Packaging ◽  
Flip Chip ◽  
Thermal Loading ◽  
Equivalent Plastic Strain ◽  
Engineering Application ◽  
Stress Strain ◽  
Element Analysis ◽  
Design Guideline ◽  
Solder Balls

As the interconnection density of electronic packaging continues to increase, the fatigueinduced solder joint failure of surface mounted electronic devices become one of the most critical reliability issues in electronic packaging industry. Especially, prediction of the shape of solder joint is a major event in the development of electronic packaging for its practical engineering application. In conventional electronic packages, the geometrical dimensions of solder balls and solder pads of the package are the same. In this research, a hybrid method combined with analytical and energybased methods is utilized to predict force-balanced heights and geometry profiles of solder balls under various solder volume and pad dimensions as well as their relative location during the reflow process. Next, a non-linear finite element analysis is adopted to investigate the stress/strain behavior of solder balls in flip chip package. The results reveal that as the flip chip package contains larger solder balls located at the corner area underneath the chip, the maximum equivalent plastic strain/stress is evidently reduced and the reliability cycles under thermal loading are enhanced. Furthermore, the results presented in this research can be used as a design guideline for area array interconnections.

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