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1 – 10 of 24Mohammad A. Gharaibeh and James M. Pitarresi
Because of growing demand for slim, thin and cheap handheld devices, reduced-volume solder interconnects like land grid array (LGA) are becoming attractive and popular choices…
Abstract
Purpose
Because of growing demand for slim, thin and cheap handheld devices, reduced-volume solder interconnects like land grid array (LGA) are becoming attractive and popular choices over the traditional ball grid array (BGA) packages. This study aims to investigate the mechanical shock and impact reliability of various solder alloys and BGA/LGA interconnect configurations.
Design/methodology/approach
Therefore, this paper uses drop testing experiments and numerical finite element simulations to evaluate and compare the reliability performance of both LGA and BGA components when exposed to drop and impact loadings. Additionally, three common solder alloys, including 63Sn37Pb, SAC305 and Innolot, are discussed.
Findings
The results of this study showed that electronic packages’ drop and impact reliability is strongly driven by the solder configuration and the alloy type. Particularly, the combination of stiff solder alloy and shorter joint, LGA’s assembled with SAC305, results in highly improved drop reliability. Moreover, the BGA packages’ performance can be considerably enhanced by using ductile and compliant solder alloys, that is, 63Sn37Pb. Finally, this paper discussed the failure mode of the various solder configurations and used simulation results to explain the crack and failure situations.
Originality/value
In literature, there is a lack of published work on the drop and impact reliability evaluation and comparison of LGA and BGA solders. This paper provides quantitative analysis on the reliability of lead-based and lead-free solders when assembled with LGA and BGA interconnects.
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This study aims to discuss the determination of the unknown in-plane mechanical material properties of printed circuit boards (PCBs) by correlating the results from dynamic…
Abstract
Purpose
This study aims to discuss the determination of the unknown in-plane mechanical material properties of printed circuit boards (PCBs) by correlating the results from dynamic testing and finite element (FE) models using the response surface method (RSM).
Design/methodology/approach
The first 10 resonant frequencies and vibratory mode shapes are measured using modal analysis with hammer testing experiment, and hence, systematically compared with finite element analysis (FEA) results. The RSM is consequently used to minimize the cumulative error between dynamic testing and FEA results by continuously modifying the FE model, to acquire material properties of PCBs.
Findings
Great agreement is shown when comparing FEA to measurements, the optimum in-plane material properties were identified, and hence, verified.
Originality/value
This paper used FEA and RSMs along with modal measurements to obtain in-plane material properties of PCBs. The methodology presented here can be easily generalized and repeated for different board designs and configurations.
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Mohammad A. Gharaibeh and Faris M. Al-Oqla
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…
Abstract
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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Mohammad Gharaibeh, Aaron J. Stewart, Quang T. Su and James M. Pitarresi
This paper aims to investigate and compare the reliability performance of land grid array (LGA) and ball grid array (BGA) solders, as well as the SAC105 and 63Sn37Pb solder…
Abstract
Purpose
This paper aims to investigate and compare the reliability performance of land grid array (LGA) and ball grid array (BGA) solders, as well as the SAC105 and 63Sn37Pb solder alloys, in vibration loading conditions.
Design/methodology/approach
Reliability tests were conducted using a sine dwell with resonance tracking vibration experiment. Finite element simulations were performed to help in understanding the observed failure trends.
Findings
Reliability results showed that the tin-lead solders out-perform lead-free solders in vibrations loading. Additionally, the LGA solder type could provide a better vibration reliability performance than BGA solders. Failure analysis results showed that in LGAs, the crack is initiated at the printed circuit board side and at the component side in BGAs. In both types, the crack is propagated throughout in the intermetallic compound layer.
Originality/value
In literature, there is a lack of published data in the comparison between LGA and BGA reliability performance in vibration loadings. This paper provides useful insights in the vibration reliability behavior of the two common solder joint types.
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This paper aims to investigate the fatigue life performance of SAC305 ball grid array solders under combined temperature and harmonic vibration loading conditions.
Abstract
Purpose
This paper aims to investigate the fatigue life performance of SAC305 ball grid array solders under combined temperature and harmonic vibration loading conditions.
Design/methodology/approach
Fatigue tests were performed using a sine dwell with resonance tracking vibration and temperature loading experiment. Finite element stress analysis was also performed to help in understanding the observed failure trends.
Findings
Fatigue test results showed that the lead-free solders tend to fail quickly in higher temperatures and higher vibration loading test conditions. The failure analysis results revealed that in low temperatures, the solder cracks are initiated and propagated at the package side. However, in high temperatures, the cracks are observed at the board side of the interconnect. In all conditions, the cracks are propagated throughout the intermetallic compound layer.
Originality/value
In the published literature, there is a lack of data in the area of fatigue assessment of lead-free solders under combined temperature and vibration loadings. This paper provides useful insights into combined thermal/vibration fatigue, i.e. reliability behavior of lead-free solder joint types.
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This paper aims to present a reliability performance assessment of electronic packages subjected to harmonic vibration loadings by using a statistical factorial analysis…
Abstract
Purpose
This paper aims to present a reliability performance assessment of electronic packages subjected to harmonic vibration loadings by using a statistical factorial analysis technique. The effects of various geometric parameters, the size and thickness of the printed circuit board and component and solder interconnect dimensions on the fundamental resonant frequency of the assembly and the axial strain of the most critical solder joint were thoroughly investigated.
Design/methodology/approach
A previously published analytical solution for the problem of electronic assembly vibration was adopted. This solution was modified and used to generate the natural frequency and solder axial strains data for various package geometries. Statistical factorial analysis was used to analyze these data.
Findings
The results of the present study showed that the reliability of electronic packages under vibration could be significantly enhanced by selecting larger and thicker printed circuit boards and thinner and smaller electrical components. Additionally, taller and thinner solders might also produce better reliability behavior.
Originality/value
The results of this investigation can be very useful in the design process of electronic products in mechanical vibration environments.
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One difficultly in building an effective finite element (FE) model of a board-level package is because of complex structure of the printed circuit board (PCB), as it contains…
Abstract
Purpose
One difficultly in building an effective finite element (FE) model of a board-level package is because of complex structure of the printed circuit board (PCB), as it contains copper layers, woven fabrics, plated-through holes and so forth. Therefore, it is often acceptable to obtain equivalent orthotropic material properties and use them in the simulation. This paper aims to provide a research methodology to produce equivalent FE models for board-level electronic packages.
Design/methodology/approach
In this methodology, the FE models’ data were correlated with experimental modal analysis results in terms of natural frequencies and mode shapes. Statistical factorial analysis was used to examine the electronic assembly material properties effect on the structure’s resonant frequencies. The equivalent material properties of the PCB were adjusted using the optimization tool available in ANSYS software for free boundary conditions. The equivalent FE model was then validated for the fixed boundary conditions.
Findings
The resultant FE models were in great match with the measured data in terms of resonant frequencies and mode shapes. The so-developed models can be further used in the analysis of the dynamic response of the electronic packages and solder interconnects.
Originality/value
The current approach provides a sophisticated research methodology to provide high-accuracy FE models of electronic assemblies subjected to vibration. The main value of this approach is to first test the effect of each material property on the package dynamic characteristics before starting the correlation process, then to automate the correlation algorithm using the built-in FE model updating feature available in ANSYS software.
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Mohammad A Gharaibeh, Markus Feisst and Jürgen Wilde
This paper aims to present two Anand’s model parameter sets for the multilayer silver–tin (AgSn) transient liquid phase (TLP) foils.
Abstract
Purpose
This paper aims to present two Anand’s model parameter sets for the multilayer silver–tin (AgSn) transient liquid phase (TLP) foils.
Design/methodology/approach
The AgSn TLP test samples are manufactured using pre-defined optimized TLP bonding process parameters. Consequently, tensile and creep tests are conducted at various loading temperatures to generate stress–strain and creep data to accurately determine the elastic properties and two sets of Anand model creep coefficients. The resultant tensile- and creep-based constitutive models are subsequently used in extensive finite element simulations to precisely survey the mechanical response of the AgSn TLP bonds in power electronics due to different thermal loads.
Findings
The response of both models is thoroughly addressed in terms of stress–strain relationships, inelastic strain energy densities and equivalent plastic strains. The simulation results revealed that the testing conditions and parameters can significantly influence the values of the fitted Anand coefficients and consequently affect the resultant FEA-computed mechanical response of the TLP bonds. Therefore, this paper suggests that extreme care has to be taken when planning experiments for the estimation of creep parameters of the AgSn TLP joints.
Originality/value
In literature, there is no constitutive modeling data on the AgSn TLP bonds.
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Mohannad Jreissat and Mohammad A. Gharaibeh
The purpose of this paper is to investigate the strain concentration factor in a central countersunk hole riveted in rectangular plates under uniaxial tension using finite element…
Abstract
Purpose
The purpose of this paper is to investigate the strain concentration factor in a central countersunk hole riveted in rectangular plates under uniaxial tension using finite element and response surface methods.
Design/methodology/approach
In this work, ANSYS software was elected to create the finite element model of the present structure, execute the analysis and generate strain concentration factor (,) data. Response surface method was implemented to formulate a second order equation to precisely compute (,) based on the geometric and material parameters of the present problem.
Findings
The computations of this formula are accurate and in a great agreement with finite element analysis (FEA) data. This equation was further used for obtaining optimum hole and plate designs.
Originality/value
An optimum design of the countersunk hole and the plate that minimizes the (,) value was achieved and hence validated with FEA findings.
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This paper aims to examine the thermal cycling fatigue life performance of two-common solder array configurations, full and peripheral, using three-dimensional nonlinear finite…
Abstract
Purpose
This paper aims to examine the thermal cycling fatigue life performance of two-common solder array configurations, full and peripheral, using three-dimensional nonlinear finite element analysis.
Design/methodology/approach
The finite element simulations were used to identify the location of the critical solder interconnect, and using Darveaux's model, solder thermal fatigue life was computed.
Findings
The results showed that the solder array type does not significantly influence thermal fatigue life of the interconnect. However, smaller size packages result in improved life by almost 45% compared to larger package designs. Additionally, this paper provided an engineered study on the effect of the number of rows available in a perimeter array component on solder thermal fatigue performance.
Originality/value
General design recommendations for reliable electronic assemblies under thermal cycling loaded were offered in this research.
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