Fatigue life models for SnAgCu and SnPb solder joints evaluated by experiments and simulation

Schubert, Andreas; Dudek, R.; Auerswald, Ellen; Gollbardt, A.; Michel, B.; Reichl, H.

doi:10.1109/ectc.2003.1216343

Cited by 310 publications

(146 citation statements)

References 8 publications

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“…Their study identified two types of creep mechanisms for steady-state deformation linked to the climb-controlled (at low stresses) and combined glide/climb (at high stresses) dislocation behaviour. Similar studies were carried out by Schubert et al [14] and Zhang et al [15], and both identified two regimes of the stress-strain rate behaviour.…”

Section: Materials Propertiessupporting

confidence: 65%

“…The hyperbolic sine creep model is adequate for most lead and lead-free solder materials, and it is used in the present study to simulate the viscous behaviour of the solder joint due to its high operating temperatures. The creep parameters, obtained by Schubert et al for Sn3.8Ag0.7Cu solder material, are used in the creep analysis [14,16].…”

Section: Materials Propertiesmentioning

confidence: 99%

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3D Study of Thermal Stresses in Lead-Free Surface Mount Devices

Hegde

Whalley

Silberschmidt

2008

Journal of Thermal Stresses

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Abstract:The paper presents the study of non-uniform temperature distributions in a flip chip electronic assembly, and the use of these temperature distributions to analyse the thermal stresses in lead-free solder joints in surface mount devices. The thermal stresses in the solder joints are mainly due to the mismatch in the coefficients of thermal expansions between the component and substrate materials, and temperature gradient in the electronic assembly. The thermo-elasto-visco-plastic finite element analysis is carried out to investigate the extent of thermal stresses induced in solder joints between a surface mount component and a FR4 circuit board (substrate) under conditions of thermal cycling with the chip resistor operating at its full power condition. Three different cases of spatial temperature distributions are considered including one with an experimentally obtained non-uniform temperature distribution. A comparative study of thermal stresses is performed using a near-eutectic SnAgCu solder material for three different thermal cases.

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Section: Materials Propertiessupporting

confidence: 65%

Section: Materials Propertiesmentioning

confidence: 99%

3D Study of Thermal Stresses in Lead-Free Surface Mount Devices

Hegde

Whalley

Silberschmidt

2008

Journal of Thermal Stresses

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“…A failure of one of the joints is recognized as an instantaneously increasing resistance. Schubert et al [48] determined the lifetime of plastic ball grid array (PBGA) assemblies this way using temperature cycles from −40 to +150 degrees Celsius. Che and Pang [49] presented experimentally determined lifetimes of PBGA packages subjected to thermal cycles with a profile ranging from −40 to +125 degrees Celsius.…”

Section: Standard Methods For Predicting the Lifetime Of Solder Jointsmentioning

confidence: 99%

“…In that case the Young's modulus of SAC405 may be set to 41 GPa and the Poisson's ratio to 0.3 [44]. A reasonable coefficent of thermal expansion for such a model would be 20 ppm/K [48]. An appropriate creep law of the following form was determined by Wiese et al [44]:ǫ used to determine the displacement rates are similar to the experimental conditions for which the creep law was determined.…”

Section: Determination Of Materials Parametersmentioning

confidence: 99%

A robust preconditioning technique for the extended finite element method

Menk

Bordas

2010

Numerical Meth Engineering

140

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In electronic devices solder joints form a mechanical as well as an electrical connection between the circuit board and the component (e.g. a chip or a resistor). Temperature variations occurring during field use cause crack initiation and crack growth inside the joints. Accurate prediction of the lifetime requires a method to simulate the damage process based on microstructural properties.Numerical simulation of developing cracks and microstructural entities such as grain boundaries and grain junctions gives rise to several problems. The solution contains strong and weak discontinuities as well as weak singularities. To obtain reasonable solutions with the finite element method (FEM) the element edges have to align with the cracks and the grain boundaries, which imposes geometrical restrictions on the mesh choice. Additionally, a large number of elements has to be used in the vicinity of the singularities which increases the computational effort. Both problems can be circumvented with the extended finite element method (X-FEM) by using appropriate enrichment functions.In this thesis the X-FEM will be developed for the simulation of complex microstructural geometries. Due to the anisotropy of the different grains forming a joint and the variety of different microstructural configurations it is not always possible to write the enrichment functions in a closed form. A procedure to determine enrichment functions numerically is explained and tested. As a result, a very simple meshing scheme, which will be introduced here, can be used to simulate developing cracks in solder joint microstructures. Due to the simplicity of the meshing algorithm the simulation can be automated completely. A large number of enrichment functions must be used to realize this. Well-conditioned equation systems, however, cannot be guaranteed for such an approach. To improve the condition number of the X-FEM stiffness matrix and thus the robustness of the solution process a preconditioning technique is derived and applied.This approach makes it possible to develop a new and fully automated procedure for addressing the reliability of solder joints numerically. The procedure relies on the random generation of microstructures. Performing crack growth calculations for a series of these structures makes it possible to address the influence of varying microstructures on the damage process. Material parameters describing the microstructure are determined in an inverse procedure. It will be shown that the numerical results correspond well with experimental observations.

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“…), versus time and temperature in cycling. [15][16][17][18][19] The results are combined with a damage function to predict the ongoing evolution of damage and failure. Our overall work is focused on this kind of approach.…”

Section: Introductionmentioning

confidence: 99%

A Mechanistic Thermal Fatigue Model for SnAgCu Solder Joints

Børgesen

Wentlent

Hamasha

et al. 2018

Journal of Elec Materi

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The present work offers both a complete, quantitative model and a conservative acceleration factor expression for the life span of SnAgCu solder joints in thermal cycling. A broad range of thermal cycling experiments, conducted over many years, has revealed a series of systematic trends that are not compatible with common damage functions or constitutive relations. Complementary mechanical testing and systematic studies of the evolution of the microstructure and damage have led to a fundamental understanding of the progression of thermal fatigue and failure. A special experiment was developed to allow the effective deconstruction of conventional thermal cycling experiments and the finalization of our model. According to this model, the evolution of damage and failure in thermal cycling is controlled by a continuous recrystallization process which is dominated by the coalescence and rotation of dislocation cell structures continuously added to during the hightemperature dwell. The dominance of this dynamic recrystallization contribution is not consistent with the common assumption of a correlation between the number of cycles to failure and the total work done on the solder joint in question in each cycle. It is, however, consistent with an apparent dependence on the work done during the high-temperature dwell. Importantly, the onset of this recrystallization is delayed by pinning on the Ag 3 Sn precipitates until these have coarsened sufficiently, leading to a model with two terms where one tends to dominate in service and the other in accelerated thermal cycling tests. Accumulation of damage under realistic service conditions with varying dwell temperatures and times is also addressed.

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Fatigue life models for SnAgCu and SnPb solder joints evaluated by experiments and simulation

Cited by 310 publications

References 8 publications

3D Study of Thermal Stresses in Lead-Free Surface Mount Devices

3D Study of Thermal Stresses in Lead-Free Surface Mount Devices

A robust preconditioning technique for the extended finite element method

A Mechanistic Thermal Fatigue Model for SnAgCu Solder Joints

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