Analysis of Stress Distribution in SnAgCu Solder Joint

SnAgCu solder is a promising lead-free material for interconnections in electronic packages. However, its melting temperature (490°K) is considerably higher than that of the traditional SnPb solder (456°K). At the same time, SnAgCu has much better creep resistance at high temperature. These properties may cause large residual stresses during manufacturing processes due to the mismatch of thermal properties of electronic components that can influence the reliability of solder joints in electronic packages. This paper studies the residual stresses in solder joints in a flip chip package under different cooling conditions and their influence on the subsequent cyclic test by means of a finite element approach. The results show that the initial temperature of 453°K is high enough to induce residual stresses due to manufacturing procedures. Simulations, based on traditional creep-fatigue models, demonstrate that the residual stresses affect the mechanical behaviour of solder joints in several initial thermal cycles but have little effect on their reliability.

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Creep–fatigue lifetime estimation of SnAgCu solder joints using an artificial neural network approach

Mechanics of Advanced Materials and Structures ◽

10.1080/15376494.2021.1951405 ◽

2021 ◽

pp. 1-7

Author(s):

Tzu-Chia Chen ◽

Wang-Wang Zhu ◽

Zi-Kun Jiao ◽

Aleksandr Mikhailovich Petrov

Keyword(s):

Neural Network ◽

Artificial Neural Network ◽

Solder Joints ◽

Network Approach ◽

Lifetime Estimation ◽

Neural Network Approach ◽

Fatigue Lifetime ◽

Snagcu Solder ◽

Creep Fatigue ◽

Artificial Neural Network Approach

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Experiment and Numerical Analysis of the Residual Stresses in Underfill Resins for Flip Chip Package Applications

Journal of Electronic Packaging ◽

10.1115/1.1849232 ◽

2005 ◽

Vol 127 (1) ◽

pp. 47-51 ◽

Cited By ~ 7

Author(s):

Man-Lung Sham ◽

Jang-Kyo Kim

Keyword(s):

Numerical Analysis ◽

Residual Stresses ◽

Integrated Circuit ◽

Flip Chip ◽

Coefficient Of Thermal Expansion ◽

Flexural Modulus ◽

Curing Temperature ◽

Electronic Packages ◽

Element Analysis ◽

Plastic Package

Polymeric encapsulant is widely used to protect the integrated circuit chips and thus to enhance the reliability of electronic packages. Residual stresses are introduced in the plastic package when the polymer is cooled from the curing temperature to ambient, from which many reliability issues arise, including warpage of the package, premature interfacial failure, and degraded interconnections. Bimaterial strip bending experiment has been employed successfully to monitor the evolution of the residual stresses in underfrill resins for flip chip applications. A numerical analysis is developed to predict the residual stresses, which agree well with the experimental measurements. The changes of material properties, such as flexural modulus and coefficient of thermal expansion, of the resins with temperature are taken into account in the finite element analysis.

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Measurement of impact toughness of eutectic SnPb and SnAgCu solder joints in ball grid array by mini-impact tester

Journal of Materials Research ◽

10.1557/jmr.2008.0186 ◽

2008 ◽

Vol 23 (5) ◽

pp. 1482-1487 ◽

Cited By ~ 9

Author(s):

Yuhuan Xu ◽

Shengquan Ou ◽

K.N. Tu ◽

Kejun Zeng ◽

Rajiv Dunne

Keyword(s):

Impact Toughness ◽

High Speed ◽

Solder Joints ◽

Ball Grid Array ◽

Snagcu Solder ◽

Snpb Solder ◽

Impact Tester ◽

Pull Tests ◽

The Impact ◽

Eutectic Snpb

The most frequent cause of failure for wireless, handheld, and portable consumer electronic products is an accidental drop to the ground. The impact may cause interfacial fracture of ball-grid-array solder joints. Existing metrology, such as ball shear and ball pull tests, cannot characterize the impact-induced high speed fracture failure. In this study, a mini-impact tester was utilized to measure the impact toughness and to characterize the impact reliability of both eutectic SnPb and SnAgCu solder joints. The annealing effect at 150 °C on the impact toughness was investigated, and the fractured surfaces were examined. The impact toughness of SnAgCu solder joints with the plating of electroless Ni/immersion Au (ENIG) became worse after annealing, decreasing from 10 or 11 mJ to 7 mJ. On the other hand, an improvement of the impact toughness of eutectic SnPb solder joints with ENIG was recorded after annealing, increasing from 6 or 10 to 15 mJ. Annealing has softened the bulk SnPb solder so that more plastic deformation can occur to absorb the impact energy.

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J0103-2-3 Evaluation of Thermal Fatigue Reliability of Solder Joints in Flip Chip Package using the Digital Image Correlation Method

The proceedings of the JSME annual meeting ◽

10.1299/jsmemecjo.2009.6.0_57 ◽

2009 ◽

Vol 2009.6 (0) ◽

pp. 57-58

Author(s):

Toshifumi KANNO ◽

Nobuyuki SHISHIDO ◽

Toru IKEDA ◽

Noriyuki MIYAZAKI ◽

Hiroyuki TANAKA ◽

...

Keyword(s):

Digital Image Correlation ◽

Thermal Fatigue ◽

Digital Image ◽

Flip Chip ◽

Solder Joints ◽

Correlation Method ◽

Image Correlation ◽

Fatigue Reliability ◽

Digital Image Correlation Method ◽

Reliability Of Solder Joints

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Importance of Creep Fatigue Interaction in Reliability of Solder Joints

2018 7th Electronic System-Integration Technology Conference (ESTC) ◽

10.1109/estc.2018.8546485 ◽

2018 ◽

Author(s):

Stephane Zanella ◽

Aurelien Lecavelier des Etangs-Levallois ◽

Eric Charkaluk ◽

Wilson Carlos Maia Filho ◽

Andrei Constantinescu

Keyword(s):

Solder Joints ◽

Creep Fatigue ◽

Reliability Of Solder Joints

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Ag3Sn Compounds Coarsening Behaviors in Micro-Joints

Materials ◽

10.3390/ma11122509 ◽

2018 ◽

Vol 11 (12) ◽

pp. 2509 ◽

Cited By ~ 3

Author(s):

Ye Tian ◽

Ning Ren ◽

Zhihua Zhao ◽

Fengshun Wu ◽

Suresh Sitaraman

Keyword(s):

Kinetic Model ◽

Thermal Shock ◽

Thermal Aging ◽

Experimental Validation ◽

Flip Chip ◽

Ostwald Ripening ◽

Solder Joints ◽

Critical Role ◽

Growth Exponent ◽

Reliability Of Solder Joints

As solder joints are being scaled down, intermetallic compounds (IMCs) are playing an increasingly critical role in the reliability of solder joints, and thereby an in-depth understanding of IMCs microstructure evolutions in micro-joints is of great significance. This study focused on coarsening behaviors of Ag3Sn compounds in Sn-3.0Ag-0.5Cu (SAC305) micro-joints of flip chip assemblies using thermal shock (TS) tests. The results showed that the Ag3Sn compounds grew and rapidly coarsened into larger ones as TS cycles increased. Compared with such coarsening behaviors during thermal aging, TS exhibited a significantly accelerating influence. This predominant contribution is quantitatively determined to be induced by strain-enhanced aging. Moreover, based on observations for Ag3Sn microstructure evolutions during TS cycling, one particular finding showed that there are two types of coarsening modes (i.e., Ostwald ripening and Necking coalescence) co-existing in the Ag3Sn coarsening process. The corresponding evolutions mechanism was elucidated in a combination of simulative analysis and experimental validation. Furthermore, a kinetic model of the Ag3Sn coarsening was established incorporating static aging and strain-enhanced aging constant, the growth exponent (n) was calculated to be 1.70, and the predominant coarsening mode was confirmed to be the necking coalescence.

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