Effective Solder for Improved Thermo-Mechanical Reliability of Solder Joints in a Ball Grid Array (BGA) Soldered on Printed Circuit Board (PCB)

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

doi:10.1007/s11664-020-08525-9

Cited by 41 publications

(31 citation statements)

References 74 publications

(71 reference statements)

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“…In electronics, the steady-state creep deformations of solder joints generally dominate the deformation kinetics due to their relatively low melting temperatures. Therefore, the inelastic response of the solder interconnections is commonly and reasonably treated as steady-state or secondary creep (Depiver et al , 2021a; Depiver et al , 2021b; Holden and Wallach, 1999; Wang et al , 1998). For this reason, Garofalo’s creep law is characteristically accepted for simulating the creep deformations of solder joints.…”

Section: Methodsmentioning

confidence: 99%

Numerical evaluation of the mechanical response of Sn-Ag-Cu lead-free solders of various silver contents

Gharaibeh,

Al-Oqla

2023

SSMT

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Purpose There are several lead-free solder alloys available in the industry. Over the years, the most favorable solder composition of tin-silver-copper (Sn-Ag-Cu [SAC]) has been vastly used and accepted for joining the electronic components. It is strongly believed that the silver (Ag) content has a significant impact on the solder mechanical behavior and thus solder thermal reliability performance. This paper aims to assess the mechanical response, i.e. creep response, of the SAC solder alloys with various Ag contents. Design/methodology/approach A three-dimensional nonlinear finite element simulation is used to investigate the thermal cyclic behavior of several SAC solder alloys with various silver percentages, including 1%, 2%, 3% and 4%. The mechanical properties of the unleaded interconnects with various Ag amounts are collected from reliable literature resources and used in the analysis accordingly. Furthermore, the solder creep behavior is examined using the two famous creep laws, namely, Garofalo’s and Anand’s models. Findings The nonlinear computational analysis results showed that the silver content has a great influence on the solder behavior as well as on thermal fatigue life expectancy. Specifically, solders with relatively high Ag content are expected to have lower plastic deformations and strains and thus better fatigue performance due to their higher strengths and failure resistance characteristics. However, such solders would have contrary fatigue performance in drop and shock environments and the low-Ag content solders are presumed to perform significantly better because of their higher ductility. Originality/value Generally, this research recommends the use of SAC solder interconnects of high silver contents, e.g. 3% and 4%, for designing electronic assemblies continuously exposed to thermal loadings and solders with relatively low Ag-content, i.e. 1% and 2%, for electronic packages under impact and shock loadings.

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Section: Methodsmentioning

confidence: 99%

Numerical evaluation of the mechanical response of Sn-Ag-Cu lead-free solders of various silver contents

Gharaibeh,

Al-Oqla

2023

SSMT

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“…In fact, Anand and Garofalo laws are widely accepted and used in electronics research studies. [36][37][38] Garofalo's creep law Garofalo's hyperbolic sine creep model 24 is commonly expressed by Garofalo-Arrhenius formula and often used to describe the temperature-initiated steady state creep response of the solder joint. Mathematically:…”

Section: Creep Laws For Lead-free Solder Jointsmentioning

confidence: 99%

Nonlinear finite element simulations on the mechanical response of the isothermally aged lead-free solders

Gharaibeh

2023

Proceedings of the Institution of Mechanical Engineers, Part L:

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The mechanical response, material properties, and mechanical failures of the lead-free solder interconnects continuously evolves and changes due to the isothermal ageing process and during thermal cycling. Therefore, it is very important to include such evolution behavior in the finite element-based evaluations of the solder thermal fatigue life analysis. The current article aims to investigate the effect of the pre-isothermal ageing on the mechanical response of the thermally cycled SAC305 lead-free interconnects utilizing finite element analysis and literature-based material parameters. Additionally, this article explores the solder creep response using two common constitutive laws, Anand and Garofalo models. The simulation results showed that the solder mechanical behavior due to thermal cycling is strongly driven by the ageing process especially for shorter time of ageing. Nonetheless, this effect becomes less effective for prolonged ageing periods. Moreover, the numerical computations proved that the solder response becomes mainly dominated by secondary creep rather than viscoplasticity when the solders are exposed to longer ageing durations. Finally, a detailed discussion on the effect of the pre-ageing process on solder plastic strains and inelastic strain energy density and hence the thermal fatigue life is presented.

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“…Both the SiC chip and AlN ceramic substrate were considered isotropic linear elastic materials. Usually, the solder is described by a unified viscoplastic model or creep model [27,28]. However, the results calculated using these constitutive models are after creep and do not reflect the state of the material before and during creep.…”

Section: Materials Propertiesmentioning

confidence: 99%

Study of Thermal Stress Fluctuations at the Die-Attach Solder Interface Using the Finite Element Method

et al. 2021

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Solder joints in electronic packages are frequently exposed to thermal cycling in both real-life applications and accelerated thermal cycling tests. Cyclic temperature leads the solder joints to be subjected to cyclic mechanical loading and often accelerates the cracking failure of the solder joints. The cause of stress generated in thermal cycling is usually attributed to the coefficients of thermal expansion (CTE) mismatch of the assembly materials. In a die-attach structure consisting of multiple layers of materials, the effect of their CTE mismatch on the thermal stress at a critical location can be very complex. In this study, we investigated the influence of different materials in a die-attach structure on the stress at the chip–solder interface with the finite element method. The die-attach structure included a SiC chip, a SAC solder layer and a DBC substrate. Three models covering different modeling scopes (i.e., model I, chip–solder layer; model II, chip–solder layer and copper layer; and model III, chip–solder layer and DBC substrate) were developed. The 25–150 °C cyclic temperature loading was applied to the die-attach structure, and the change of stress at the chip–solder interface was calculated. The results of model I showed that the chip–solder CTE mismatch, as the only stress source, led to a periodic and monotonic stress change in the temperature cycling. Compared to the stress curve of model I, an extra stress recovery peak appeared in both model II and model III during the ramp-up of temperature. It was demonstrated that the CTE mismatch between the solder and copper layer (or DBC substrate) not only affected the maximum stress at the chip–solder interface, but also caused the stress recovery peak. Thus, the combined effect of assembly materials in the die-attach structure should be considered when exploring the joint thermal stresses.

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Effective Solder for Improved Thermo-Mechanical Reliability of Solder Joints in a Ball Grid Array (BGA) Soldered on Printed Circuit Board (PCB)

Cited by 41 publications

References 74 publications

Numerical evaluation of the mechanical response of Sn-Ag-Cu lead-free solders of various silver contents

Numerical evaluation of the mechanical response of Sn-Ag-Cu lead-free solders of various silver contents

Nonlinear finite element simulations on the mechanical response of the isothermally aged lead-free solders

Study of Thermal Stress Fluctuations at the Die-Attach Solder Interface Using the Finite Element Method

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