A Comprehensive Study of Electromigration in Lead-free Solder Joint

Xu, Jiefeng; Cai, Chongyang; Pham, V.D.; Pan, Ke; Wang, Huayan; Park, Seungbae

doi:10.1109/ectc32862.2020.00054

Cited by 18 publications

(3 citation statements)

References 12 publications

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“…As the current development of electronic products favors miniaturization and integration, the scale of micro-solder joints is becoming smaller, resulting in an increase in the current density carried by the solder joints [10][11][12]. At high current densities, solder joints generate not only electromigration [13,14] but also a large amount of Joule heat [15,16], which seriously affects the reliability of solder joints and has become one of the most important areas in current research [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Properties of Electromigration of Sn58Bi/Cu Solder Joints with Different Joule Thermal Properties

Gao

Zhang

et al. 2023

Metals

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Electromigration is one of the most important research issues affecting the reliability of solder joints. Current-induced Joule heating affects the electromigration behavior of solder joints. Solder joints with different cross-sectional areas were designed to obtain different Joule heating properties. The effects of the interfacial intermetallic compound (IMC) and mechanical properties of Sn58Bi/Cu solder joints were studied for different Joule heating properties. The results showed that as the cross-sectional area of the Sn58Bi/Cu solder joints increased, the Joule heating of the joint increased. The anode IMC thickness of the joint thickened and transformed into a planar shape. The Bi migrated to the anode region to form a Bi-rich layer and gradually increased in thickness. The cathode IMC thickness first increased, then decreased, and gradually dissolved. The Sn-rich layer formed near the solder side and gradually increased in thickness, with microcracks occurring when the cross-sectional area of the joint increased to 0.75 mm2. The joint shear fracture path moved from the soldering zone near the cathode IMC layer to the interfacial IMC layer. The fracture mechanism of the joint changed from a mixed brittle/tough fracture, dominated by deconstruction and secondary cracking, to a brittle fracture dominated by deconstruction. The joint shear strength was reduced by 60.9% compared to that in the absence of electromigration.

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Section: Introductionmentioning

confidence: 99%

Microstructure and Properties of Electromigration of Sn58Bi/Cu Solder Joints with Different Joule Thermal Properties

Gao

Zhang

et al. 2023

Metals

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“…The process aims to form robust solder joints as the mechanical and electrical connections between the components and the PCB (Pan et al , 2019). Properly developed the reflow profile can achieve defect-free solder joints by eliminating skewing, bridging, voiding, insufficient wetting, solder balling, tombstoning, dewetting, intermetallic compound excessiveness and other issues (Wang et al , 2010; Xu et al , 2020). However, the temperature profiles of solder joints under the components are hard to measure directly.…”

Section: Introductionmentioning

confidence: 99%

An intelligent system for reflow oven temperature settings based on hybrid physics-machine learning model

Lai

Pan

Cen

et al. 2022

SSMT

Self Cite

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Purpose This paper aims to provide the proper preset temperatures of the convection reflow oven when reflowing a printed circuit board (PCB) assembly with varied sizes of components simultaneously. Design/methodology/approach In this study, computational fluid dynamics modeling is used to simulate the reflow soldering process. The training data provided to the machine learning (ML) model is generated from a programmed system based on the physics model. Support vector regression and an artificial neural network are used to validate the accuracy of ML models. Findings Integrated physical and ML models synergistically can accurately predict reflow profiles of solder joints and alleviate the expense of repeated trials. Using this system, the reflow oven temperature settings to achieve the desired reflow profile can be obtained at substantially reduced computation cost. Practical implications The prediction of the reflow profile subjected to varied temperature settings of the reflow oven is beneficial to process engineers when reflowing bulky components. The study of reflowing a new PCB assembly can be started at the early stage of board design with no need for a physical profiling board prototype. Originality/value This study provides a smart solution to determine the optimal preset temperatures of the reflow oven, which is usually relied on experience. The hybrid physics–ML model providing accurate prediction with the significantly reduced expense is used in this application for the first time.

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“…Some researchers have tried to optimize Black’s formula. Xu used an n value of 2 for ball grid array (BGA) solder joints (Xu et al , 2020). Tu’s group conducted a series of tests on solder joints and the calculated value of n was 15 (Choi et al , 2003).…”

Section: Introductionmentioning

confidence: 99%

A study on the effects of electrical and thermal stresses on void formation and migration lifetime of Sn3.0Ag0.5Cu solder joints

Wan

et al. 2021

SSMT

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Purpose The purpose of this study is to investigate the effect of electrical and thermal stresses on the void formation of the Sn3.0Ag0.5Cu (SAC305) lead-free ball grid array (BGA) solder joints and to propose a modified mean-time-to-failure (MTTF) equation when joints are subjected to coupling stress. Design/methodology/approach The samples of the BGA package were subjected to a migration test at different currents and temperatures. Voltage variation was recorded for analysis. Scanning electron microscope and electron back-scattered diffraction were applied to achieve the micromorphological observations. Additionally, the experimental and simulation results were combined to fit the modified model parameters. Findings Voids appeared at the corner of the cathode. The resistance of the daisy chain increased. Two stages of resistance variation were confirmed. The crystal lattice orientation rotated and became consistent and ordered. Electrical and thermal stresses had an impact on the void formation. As the current density and temperature increased, the void increased. The lifetime of the solder joint decreased as the electrical and thermal stresses increased. A modified MTTF model was proposed and its parameters were confirmed by theoretical derivation and test data fitting. Originality/value This study focuses on the effects of coupling stress on the void formation of the SAC305 BGA solder joint. The microstructure and macroscopic performance were studied to identify the effects of different stresses with the use of a variety of analytical methods. The modified MTTF model was constructed for application to SAC305 BGA solder joints. It was found suitable for larger current densities and larger influences of Joule heating and for the welding ball structure with current crowding.

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A Comprehensive Study of Electromigration in Lead-free Solder Joint

Cited by 18 publications

References 12 publications

Microstructure and Properties of Electromigration of Sn58Bi/Cu Solder Joints with Different Joule Thermal Properties

Microstructure and Properties of Electromigration of Sn58Bi/Cu Solder Joints with Different Joule Thermal Properties

An intelligent system for reflow oven temperature settings based on hybrid physics-machine learning model

A study on the effects of electrical and thermal stresses on void formation and migration lifetime of Sn3.0Ag0.5Cu solder joints

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