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.

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 Analysis of Solder Joints in Flip Chip Bonding

1999 ◽  
Vol 122 (3) ◽  
pp. 207-213 ◽  
Author(s):  
Yutaka Tsukada ◽  
Hideo Nishimura ◽  
Masao Sakane ◽  
Masateru Ohnami
Keyword(s):  
Fatigue Life ◽  
Flip Chip ◽  
Printed Circuit Board ◽  
Electrical Potential ◽  
Potential Drop ◽  
Life Assessment ◽  
Circuit Board ◽  
Ratchet Effect ◽  
The Difference ◽  
Fatigue Life Analysis

This paper describes the life assessment of flip chip joints. Flip chip joints of 63Sn-37Pb and 5Sn-95Pb solders on a printed circuit board were stressed thermally for fatigue. Fatigue lives of the joints were determined by an electrical potential drop method and the effect of encapsulation on fatigue life was discussed. The encapsulation had a significant effect of prolonging the fatigue life of the joints. Thermo-mechanical finite element analyses proved that the encapsulation lowered the strain amplitude of the joints by distributing the strain over a whole package and bending effect. Cracking location was also discussed in relation with the strain concentration in the joints. Fatigue lives of the flip chip joints were compared with those of bulk round bar specimens and the difference in fatigue life between two types of specimens was discussed from the specimen dimensions and ratchet effect. [S1043-7398(00)00203-6]

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.

Visco-Elastic Effect of Underfill Material in Reliability Analysis of Flip-Chip Package

2009 ◽  
Author(s):  
Yoshihiko Kanda ◽  
Kunihiro Zama ◽  
Yoshiharu Kariya ◽  
Takao Mikami ◽  
Takaya Kobayashi ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Reliability Analysis ◽  
Flip Chip ◽  
Cooling Process ◽  
Thermal Cycling Condition ◽  
Solder Bumps ◽  
The Difference ◽  
Analytical Result ◽  
Underfill Material ◽  
Cycling Condition

The effect of viscoelasticity of underfill on the reliability analysis of flip-chip package by using FEA has been investigated in this study. The analytical result on thermal warpage of a package is different depending on whether the underfill is assumed to be elastic or viscoelastic. The difference is prominent in materials with low Tg, specifically during the cooling process. The viscoelastic effect of the underfill on the fatigue life of the solder bumps is also appears in materials with low Tg, and the predicted fatigue life of a package is about twice as short if the underfill is assumed to be elastic instead of viscoelastic. Thus, the differences in the assumption regarding the viscoelastic properties of the underfill affect the reliability analysis of the packages under thermal cycling condition using FEA.

scholarly journals Fiber Bragg Grating Sensors For Failure Detection Of Fip Chip BGA In Four-Point Bending Test

2021 ◽  
Author(s):  
Rasha Hussain
Keyword(s):  
Fiber Bragg Grating ◽  
Flip Chip ◽  
Structural Integrity ◽  
Failure Detection ◽  
New Method ◽  
Bending Test ◽  
Bragg Grating ◽  
Test Configuration ◽  
Mechanical Bending ◽  
Free Solder

Maintaining structural integrity is an important issue for advanced flip chip ball grid array (FC-BFA) packages especially due to the use of Pb-free solder replacing the Pb-contained solders and the large package size induced mechanical vulnerability. For such packages, the mechanical bending causes fracture in the interconnecting plastic PWB. To determine the critical load becomes a challenge to assembly manufacturers since the conventional testing methods based on monitoring electric continuity of the daisy chained solder joints fail to detect the PWB de-bonding near the interconnect. This thesis researches a new method that uses the Fiber Bragg Grating sensor to detect the interconnect fracture failure of 55 mm lead-free FC-BGA under four-point bend test. Experimental setups and procedures are studied, a proper test configuration is determined and a series of testing performed. The validity of the new method in monitoring the solder joint de-bonding is proved through analyzing the test results, which shows that the FBG sensors are sensitive to capture the onset of the fracture in different cases.

scholarly journals Environment-assisted fatigue of steel bridges: A conceptual framework for life assessment

2021 ◽  
Vol 1201 (1) ◽  
pp. 012045
Author(s):  
J S S Sandviknes ◽  
N D Adasooriya ◽  
D Pavlou ◽  
T Hemmingsen
Keyword(s):  
Fatigue Life ◽  
Structural Integrity ◽  
Steel Bridges ◽  
Life Assessment ◽  
Steel Bridge ◽  
Corrosive Environment ◽  
Railway Bridge ◽  
Strength Curve ◽  
The Difference

Abstract This paper presents a framework based on a recently proposed fatigue strength curve of corroded steel to assess the life of an existing steel bridge exposed to environment-assisted fatigue. Environment-assisted cracking (EAC) and how it affects the structural integrity of steel bridges are introduced by the framework. Determination of both corroded and uncorroded details in a corrosive environment are also included in this framework. To conform the applicability and significance, a fatigue life of a railway bridge was assessed by methods given in the framework. The obtained fatigue lives were compared. The difference of the estimated fatigue lives emphasizes the importance of having this framework to consider the interaction of corrosion and fatigue mechanisms.

Application of Finite Element Method in Optimal Design of Flip-Chip Package

2011 ◽  
Vol 264-265 ◽  
pp. 1660-1665
Author(s):  
Yong Cheng Lin ◽  
Yu Chi Xia
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Solder Joint ◽  
Thermal Fatigue ◽  
Flip Chip ◽  
Solder Joints ◽  
Temperature Cycling ◽  
Lead Free ◽  
Lead Free Solder ◽  
Free Solder

More and more solder joints in circuit boards and electronic products are changing to lead free solder, placing an emphasis on lead free solder joint reliability. Solder joint fatigue failure is a serious reliability concern in area array technologies. In this study, the effects of substrate materials on the solder joint thermal fatigue life were investigated by finite element model. Accelerated temperature cycling loading was imposed to evaluate the reliability of solder joints. The thermal strain/stress in solder joints of flip chip assemblies with different substrates was compared, and the fatigue life of solder joints were evaluated by Darveaux’s crack initiation and growth model. The results show the mechanisms of substrate flexibility on improving solder joint thermal fatigue.

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