Prediction of damage and fatigue life of high-temperature flip chip assembly interconnections at operations

Amalu, Emeka H.; Ekere, N.N.

doi:10.1016/j.microrel.2012.04.004

Cited by 15 publications

(3 citation statements)

References 41 publications

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“…Formation of complete hysteresis loop up to the sixth thermal cycles supports earlier finding reported by Amalu and Ekere [28] and thus the authors emphasise the use of at least six temperature cycles in thermo-mechanical investigation of solder joints in not only electronic assemblies but also in photovoltaic modules. The results of the computation of fatigue life of the solder joints using the two relations demonstrates that the employment of creep strain energy and the model based on it give a better result than creep strain and its model.…”

Section: Discussionsupporting

confidence: 86%

Evaluation of thermo-mechanical damage and fatigue life of solar cell solder interconnections

Zarmai

Ekere

Oduoza

et al. 2017

Robotics and Computer-Integrated Manufacturing

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The soldering process of interconnecting crystalline silicon solar cells to form photovoltaic (PV) module is a key manufacturing process. However, during the soldering process, stress is induced in the solar cell solder joints and remains in the joint as residual stress after soldering. Furthermore, during the module service life time, thermo-mechanical degradation of the solder joints occurs due to thermal cycling of the joints which induce stress, creep strain and strain energy. The resultant effect of damage on the solder joint is premature failure, hence shortened fatigue life. This study seeks to determine accumulated thermo-mechanical damage and fatigue life of solder interconnection in solar cell assembly under thermo-mechanical cycling conditions. In this investigation, finite element modelling (FEM) and simulations are carried out in order to determine nonlinear degradation of SnAgCu solder joints. The degradation of the solder material is simulated using Garofalo-Arrhenius creep model. A three dimensional (3D) geometric model is subjected to six accelerated thermal cycles (ATCs) utilising IEC 61215 standard for photovoltaic panels. The results demonstrate that induced stress, strain and strain energy impacts the solder joints during operations. Furthermore, the larger the accumulated creep strain and creep strain energy in the joints, the shorter the fatigue life. This indicates that creep strain and creep strain energy in the solder joints significantly impacts the thermo-mechanical reliability of the assembly joints. Regions of solder joint with critical stress, strain and strain energy values including their distribution are determined. Analysis of results demonstrates that creep energy density is a better parameter than creep strain in predicting interconnection fatigue life. The use of six ATCs yields significant data which enable better understanding of the response of the solder joints to the induced loads. Moreover, information obtained from this study can be used for improved design and better-quality fabrication of solder interconnections in solar cell assembly for enhanced thermo-mechanical reliability

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Section: Discussionsupporting

confidence: 86%

Evaluation of thermo-mechanical damage and fatigue life of solar cell solder interconnections

Zarmai

Ekere

Oduoza

et al. 2017

Robotics and Computer-Integrated Manufacturing

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“…Several researches have investigated the effect of intermetallic compound (IMC) layer on solder joint reliability (Amalu et al, 2011;Ekere, 2012a, 2012b;George, 2010;Nadimpalli and Spelt, 2011;Xiao et al, 2013). Amalu and Ekere, (2012a), in their prediction of damage and fatigue life of high-temperature flip chip assembly interconnections at operations, utillised 3D flip chip models simulated in ANSYS 13 to investgate the damage of bonded materials. They ascertained the IMC layer between solder and copper die as most vulnerable to crack initiation and propagation.…”

Section: Effect Of Cycle Number On Determination Of Accurate Degradatmentioning

confidence: 99%

Effect of operating temperature on degradation of solder joints in crystalline silicon photovoltaic modules for improved reliability in hot climates

et al. 2018

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Accelerated degradation of solder joint interconnections in crystalline silicon photovoltaic (c-Si PV) modules drives the high failure rate of the system operating in elevated temperatures. The phenomenon challenges the thermo-mechanical reliability of the system for hot climatic operations. This study investigates the degradation of solder interconnections in c-Si PV modules for cell temperature rise from 25°C STC in steps of 1°C to 120°C. The degradation is measured using accumulated creep strain energy density (). Generated magnitudes are utilised to predict the fatigue life of the module for ambient temperatures ranging from European to hot climates. The ANSYS mechanical package coupled with the IEC 61215 standard accelerated thermal cycle (ATC) profile is employed in the simulation. The Garofalo creep model is used to model the degradation response of solder while other module component materials are simulated with appropriate material models. Solder degradation is found to increase with every 1°C cell temperature rise from the STC. Three distinct degradation rates in Pa/°C are observed. Region 1, 25 to 42°C, is characterised by degradation rate increasing quadratically from 1.53 to 10.03 Pa/°C. The degradation rate in region 2 ,43 to 63 °C, is critical with highest constant magnitude of 12.06 Pa/°C. Region 3, 64 to 120°C, demonstrates lowest degradation rate of logarithmic nature with magnitude 5.47 at the beginning of the region and 2.25 Pa/°C at the end of the region. The module fatigue life, L (in years) is found to decay according to the power function = 721.48 −1.343. The model predicts module life in London and hot climate to be 18.5 and 9 years, respectively. The findings inform on the degradation of c-Si PV module solder interconnections in different operating ambient temperatures and advise on its operational reliability for improved thermo-mechanical design for hot climatic operations.

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“…Therefore, in the finite element modelling, the thickness of the silicon die is reduced to 33 µm, and the processing time of the solution in our PC (Intel i7 cpu and 16 gb memory) is about 100 hours. The solder joints are particularly vulnerable to crack initiations at the die-solder interconnect [8], resulting in great interest of the reliability of this region. The silicon die thickness of 33 µm was determined by calibrating the focal point of the virtual transducer into the middle of the UBM structure to achieve an optimal focus at the UBM structure.…”

Section: Finite Element Modellingmentioning

confidence: 99%

Development of C-Line plot technique for the characterization of edge effects in acoustic imaging: A case study using flip chip package geometry

Lee

Zhang

Harvey

et al. 2015

Microelectronics Reliability

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Edge effect is a common phenomenon observed in Acoustic micro imaging of microelectronic packages. In this paper, using flip chip package geometry as a test vehicle, finite element modelling is carried out to study the fundamental mechanism of the edge effect phenomenon. C-line plot technique is developed for characterisation of edge effects in acoustic C-scan images, in particular solder joint C-scan images. Simulated results are compared to experimental results. Results reveal that edge effect generation is mainly attributed to the under-bump-metallisation structure. In addition, through analysis of the CLine profile of edge effects, the impact of the transducer focal point and the spot size on the edge effect is investigated. Results show that slight off-focus can reduce the severity of the edge effect in which image sharpness is a trade-off.

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Prediction of damage and fatigue life of high-temperature flip chip assembly interconnections at operations

Cited by 15 publications

References 41 publications

Evaluation of thermo-mechanical damage and fatigue life of solar cell solder interconnections

Evaluation of thermo-mechanical damage and fatigue life of solar cell solder interconnections

Effect of operating temperature on degradation of solder joints in crystalline silicon photovoltaic modules for improved reliability in hot climates

Development of C-Line plot technique for the characterization of edge effects in acoustic imaging: A case study using flip chip package geometry

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