Creep Damage of BGA Solder Interconnects Subjected to Thermal Cycling and Isothermal Ageing

Depiver, Joshua Adeniyi; Mallik, Sabuj; Harmanto, Dani; Amalu, Emeka H.

doi:10.1109/eptc47984.2019.9026710

Cited by 9 publications

(3 citation statements)

References 31 publications

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“…The BGA package includes solder ball, Silicon (Si), die substrate, Copper (Cu) pad and epoxy-resin (FR-4). The parameters and package dimensions of the lead-free solder BGA are shown in the author's other publications Depiver et al [62], [63]. The necessity to use a quarter of the full model is to reduce simulation solve time and processes since the aim of the research is to investigate BGA solder joint in the package for thermo-mechanical reliability.…”

Section: A3 Geometrical and Mesh Modelsmentioning

confidence: 99%

Comparing and Benchmarking Fatigue Behaviours of Various SAC Solders under Thermo-Mechanical Loading

Depiver

Mallik

Amalu

2020

2020 IEEE 8th Electronics System-Integration Technology Conference (ESTC)

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While the fatigue behaviours (including fatigue life predictions) of lead-free solder joints have been extensively researched in the last 15 years, these are not adequately compared and benchmarked for different lead-free solders that are being used. As more and more fatigue properties of lead-free solders are becoming available, it is also critical to know how fatigue behaviours differ under different mathematical models. This paper addresses the challenges and presents a comparative study of fatigue behaviours of various mainstream lead-free SnAg -Cu (SAC) solders and benchmarked those with lead-based eutectic solder. Creep-induced fatigue and fatigue life of leadbased eutectic Sn63Pb37 and four lead-free SAC solder alloys: SAC305, SAC387, SAC396 and SAC405 are analysed through simulation studies. The Anand model is used to simulate the inelastic deformation behaviour of the solder joints under accelerated thermal cycling (ATC). It unifies the creep and rateindependent plastic behaviour and it is used to predict the complex stress-strain relationship of solders under different temperatures and strain rates, which are required in the prediction of fatigue life using the fatigue life models such as Engelmaier, Coffin-Mason and Solomon as the basis of our comparison. The ATC was carried out using temperature range from − ℃ ℃. The fatigue damage propagation is determined with finite element (FE) simulation, which allows virtual prototyping in the design process of electronics devices. The simulation was carried out on a BGA (36 balls, × matrix) mounted onto Cu padded substrate. Results are analysed for plastic strain, Von mises stress, strain energy density, and stress-strain hysteresis loop. The simulation results show that the fatigue behaviours of lead-based eutectic Sn63Pb37 solder is comparable to those of lead-free SAC solders. Among the four SAC solders, SAC387 consistently produced higher plastic strain, strain energy and stress than the other solders. The fatigue life's estimation of the solder joint was investigated using Engelmaier, Coffin-Manson, and Solomon models. Results obtained show that SAC405 has the highest fatigue life (25.7, 21.1 and 19.2 years) followed by SAC396 (18.7, 20.3 and 17.9 years) and SAC305 (15.2, 13.6 and 16.2 years) solder alloys respectively. Predicting the fatigue life of these solder joints averts problems in electronics design for reliability and quality, which if not taken care of, may result in lost revenue. Predictive fatigue analysis can also considerably reduce premature failure, and modern analysis technique such as one used in this research is progressively helping to provide comprehensive product life expectancy data.

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Section: A3 Geometrical and Mesh Modelsmentioning

confidence: 99%

Comparing and Benchmarking Fatigue Behaviours of Various SAC Solders under Thermo-Mechanical Loading

Depiver

Mallik

Amalu

2020

2020 IEEE 8th Electronics System-Integration Technology Conference (ESTC)

Self Cite

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“…The reliability of lead-free solder joints, especially under variable operational conditions such as thermal fluctuations and mechanical stress, is of paramount interest. These conditions precipitate thermomechanical fatigue and creep deformation, manifesting in microstructural changes consequential for joint integrity [9]- [16]. This investigation advances a thorough Finite Element Analysis (FEA) to appraise the effects of thermomechanical fatigue and creep deformation on the microstructural evolution and reliability of lead-free Sn-Ag-Cu (SAC) solder joints.…”

Section: Introductionmentioning

confidence: 97%

Comparative Analysis of SAC Solder Alloys for Enhanced Reliability in Electronic Assemblies: A Finite Element Approach

Depiver,

Mallik,

Amalu

2024

Preprint

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In an era where environmental sustainability and electronic reliability are paramount, this study provides a critical quantitative analysis of lead-free Sn-Ag-Cu (SAC) solder joints, employing Finite Element Analysis (FEA) to scrutinise their thermomechanical fatigue and creep deformation characteristics. The investigation juxtaposes four SAC solder alloys (SAC305, SAC387, SAC396, and SAC405) against traditional lead-based Sn63Pb37 solder to elucidate their microstructural evolution and ensure long-term reliability. FEA simulations disclose that SAC387 alloy exhibits the highest yield stress at 58 MPa, whereas SAC405 shows remarkable resilience with the lowest stress accumulation, characterised by σ = 1.543T – 34.983. Isothermal ageing studies demonstrate SAC387’s accelerated creep response, indicating a higher susceptibility to failure. Conversely, SAC405's steadfast nature under isothermal ageing is marked by the least strain and deformation rates, enhancing its reliability. Strain distribution analyses further reveal that SAC405 alloys endure the lowest strain levels, contrasting with SAC387, which experiences substantial deformation and leads to strain energy density—a key longevity indicator. Thus, SAC405 and Sn63Pb37 record the lowest strain energy densities, highlighting their robustness. These findings provide a comprehensive assessment of SAC solder alloys, focusing on their stress, strain, energy density, and strain rates. The reliance on FEA for predictive analysis indicates the potential for pre-empting failure, offering a valuable framework for electronic manufacturers in selecting and optimising solder materials. This study illuminates the intricate dynamics of SAC solder joints under thermomechanical stress, serving as an indispensable resource for designing robust and sustainable electronics that align with the industry’s environmental responsibilities.

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“…Discontinuous recrystallisation can also take place because of the presence of grain boundaries and second-phase particles (IMCs), which act as obstacles to dislocation movement and cause localised dislocation pileup. 30,31,[33][34][35][36] While there is important ongoing work on the macroscopic creep response of solders, [37][38][39][40] there is also a need for studies that account for crystallographic orientations and the microstructure at both the b-Sn dendrite scale and the Ag 3 Sn and Cu 6 Sn 5 particle scale. The studies above did not include information on crystallographic orientation and microstructural evolution during creep deformation, which may play a significant role.…”

Section: Introductionmentioning

confidence: 99%

The Role of Lengthscale in the Creep of Sn-3Ag-0.5Cu Solder Microstructures

Gourlay

Britton

2021

Journal of Elec Materi

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Creep of directionally solidified Sn-3Ag-0.5Cu wt.% (SAC305) samples with near-<110> orientation along the loading direction and different microstructural lengthscale is investigated under constant load tensile testing and at a range of temperatures. The creep performance improves by refining the microstructure, i.e. the decrease in secondary dendrite arm spacing (λ2), eutectic intermetallic spacing (λe) and intermetallic compound (IMC) size, indicating a longer creep lifetime, lower creep strain rate, change in activation energy (Q) and increase in ductility and homogeneity in macro- and micro-structural deformation of the samples. The dominating creep mechanism is obstacle-controlled dislocation creep at room temperature and transits to lattice-associated vacancy diffusion creep at elevated temperature ($$ \frac{T}{{T_{M} }} $$ T T M > 0.7 to 0.75). The deformation mechanisms are investigated using electron backscatter diffraction and strain heterogeneity is identified between β-Sn in dendrites and β-Sn in eutectic regions containing Ag3Sn and Cu6Sn5 particles. The size of the recrystallised grains is modulated by the dendritic and eutectic spacings; however, the recrystalised grains in the eutectic regions for coarse-scaled samples (largest λ2 and λe) is only localised next to IMCs without growth in size.

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Creep Damage of BGA Solder Interconnects Subjected to Thermal Cycling and Isothermal Ageing

Cited by 9 publications

References 31 publications

Comparing and Benchmarking Fatigue Behaviours of Various SAC Solders under Thermo-Mechanical Loading

Comparing and Benchmarking Fatigue Behaviours of Various SAC Solders under Thermo-Mechanical Loading

Comparative Analysis of SAC Solder Alloys for Enhanced Reliability in Electronic Assemblies: A Finite Element Approach

The Role of Lengthscale in the Creep of Sn-3Ag-0.5Cu Solder Microstructures

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