Reliability modeling and assessment of solder joints of electronic assemblies under mixed exposure to mechanical loads

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Supriyono ◽  
Tzu-Chia Chen ◽  
Lis M. Yapanto ◽  
Zagir Azgarovich Latipov ◽  
Angelina Olegovna Zekiy ◽  
...  
Keyword(s):  
Solder Joint ◽  
Failure Process ◽  
Estimation Model ◽  
Lifetime Estimation ◽  
Simultaneous Exposure ◽  
Electronic Assembly ◽  
Mechanical Loads ◽  
Content Type ◽  
Electronic Assemblies ◽  
Mixed Exposure

Purpose In this paper, a lifetime estimation model for the solder joint is proposed which is capable of considering both severe and running mechanical shocks which is the real case in electric converters in the automotive and aerospace applications. This paper aims to asses the reliability of the solder joint under mixed exposure of mechanical loads. Design/methodology/approach Mechanical failure process may put at risk the perfect performance of any kinds of electronic systems regardless of the applications they are prepared for. Observation of solder joint health in an electronic assembly under simultaneous exposure of severe and running shocks is an open problem. Three commonly used soldering compositions are considered while the electronic assembly is exposed to three well-known driving cycles. Findings The results show that the best performance is achieved using SAC405 soldering alloy in comparison with Sn63Pb37 and SAC387 solder alloy. Consideration of mixed exposure to the mechanical loads leads to much more accurate lifetime estimation of the solder joint in the electronic assemblies. Originality/value The originality of the paper is confirmed.

Accurate composition dependent thermo mechanical lifetime estimation of hour glass type solder joint in electronic assemblies

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Leonid Anatolevich Olenev ◽  
Rafina Rafkatovna Zakieva ◽  
Nina Nikolaevna Smirnova ◽  
Rustem Adamovich Shichiyakh ◽  
Kirill Aleksandrovich Ershov ◽  
...  
Keyword(s):  
Finite Element ◽  
Chemical Composition ◽  
Solder Joint ◽  
Design Methodology ◽  
Lifetime Estimation ◽  
Creep Tests ◽  
Content Type ◽  
Element Simulation ◽  
Glass Type ◽  
Electronic Assemblies

Purpose This study aims to present a more accurate lifetime prediction model considering solder chemical composition. Design/methodology/approach Thermal cycling and standard creep tests as well as finite element simulation were used. Findings The study found lower error in the solder joint lifetime evaluation. The higher the Ag content is, the higher the lifetime is achieved. Originality/value It is confirmed.

Profitability of the Northern Sea Route for liquid bulk shipping under post 2020 sulphur regulations

2020 ◽  
Vol 31 (2) ◽  
pp. 313-332
Author(s):  
Tuomo Keltto ◽  
Su-Han Woo
Keyword(s):  
Spot Market ◽  
The Arctic ◽  
Future Research ◽  
Estimation Model ◽  
Content Type ◽  
Freight Rates ◽  
Northern Sea Route ◽  
Financial Perspective ◽  
The Baltic ◽  
Regulation Compliance

PurposeThe purpose of this study is to evaluate the profitability of the Northern Sea Route (NSR) as a shipping lane from the financial perspective of shipping companies under post 2020 sulphur regulations.Design/methodology/approachThis study develops profit estimation model, and the profitability of the NSR is assessed for a Handymax Medium Range (MR) tanker vessel using scenarios in combination with spot market earning levels, the regulation compliance method and destination ports. The required freight rates are calculated to justify the decision of shipowners to transit a tanker from the Baltic spot market to the NSR navigation.FindingsResults suggest that the required freight rates from the Arctic trade to justify the transit to the NSR are higher than the actual agreed rates in the past, which implies low viability of the NSR as a regular shipping lane. It was also found that the required freight rates are affected by the spot market earning levels, compliance method and duration of the voyage.Research limitations/implicationsThis study takes a new approach on assessing the NSR viability by comprehensively assessing the annual profitability and including the spot market trade as an opportunity cost for the NSR shipping. Despite various scenarios used in this study, a sensitivity analysis would be useful for future research.Practical implicationsThis study suggests how much freight rates a shipping company would need to charge if it were to offer tanker shipping services to four major Asian ports while simultaneously operating at the Baltic Sea during the remainder of the year.Originality/valueThis study adopts a market-oriented approach by incorporating both earnings and costs (including opportunity costs) in the profitability model rather than merely analyzing the total cost of shipping via the NSR. This study also analyzes impact of IMO 2020 Sulphur regulation on the NSR profitability.

Effects of doping trace Ni element on interfacial behavior of Sn/Ni (polycrystal/single-crystal) joints

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jianing Wang ◽  
Jieshi Chen ◽  
Zhiyuan Zhang ◽  
Peilei Zhang ◽  
Zhishui Yu ◽  
...  
Keyword(s):  
Solder Joint ◽  
Single Crystal ◽  
Microstructure Evolution ◽  
Thermal Aging ◽  
Interfacial Layer ◽  
Aging Treatment ◽  
Growth Behavior ◽  
Reflow Process ◽  
Content Type ◽  
Ni Substrate

Purpose The purpose of this article is the effect of doping minor Ni on the microstructure evolution of a Sn-xNi (x = 0, 0.05 and 0.1 wt.%)/Ni (Poly-crystal/Single-crystal abbreviated as PC Ni/SC Ni) solder joint during reflow and aging treatment. Results showed that the intermetallic compounds (IMCs) of the interfacial layer of Sn-xNi/PC Ni joints were Ni3Sn4 phase, while the IMCs of Sn-xNi/SC Ni joints were NiSn4 phase. After the reflow process and thermal aging of different joints, the growth behavior of interfacial layer was different due to the different mechanism of element diffusion of the two substrates. The PC Ni substrate mainly provided Ni atoms through grain boundary diffusion. The Ni3Sn4 phase of the Sn0.05Ni/PC Ni joint was finer, and the diffusion flux of Sn and Ni elements increased, so the Ni3Sn4 layer of this joint was the thickest. The SC Ni substrate mainly provided Ni atoms through the lattice diffusion. The Sn0.1Ni/SC Ni joint increases the number of Ni atoms at the interface due to the doping of 0.1Ni (wt.%) elements, so the joint had the thickest NiSn4 layer. Design/methodology/approach The effects of doping minor Ni on the microstructure evolution of an Sn-xNi (x = 0, 0.05 and 0.1 Wt.%)/Ni (Poly-crystal/Single-crystal abbreviated as PC Ni/SC Ni) solder joint during reflow and aging treatment was investigated in this study. Findings Results showed that the intermetallic compounds (IMCs) of the interfacial layer of Sn-xNi/PC Ni joints were Ni3Sn4 phase, while the IMCs of Sn-xNi/SC Ni joints were NiSn4 phase. After the reflow process and thermal aging of different joints, the growth behavior of the interfacial layer was different due to the different mechanisms of element diffusion of the two substrates. Originality/value In this study, the effect of doping Ni on the growth and formation mechanism of IMCs of the Sn-xNi/Ni (single-crystal) solder joints (x = 0, 0.05 and 0.1 Wt.%) was investigated.

Modeling multi-state system reliability analysis in a power station under fatal and nonfatal shocks: a simulation approach

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammad Reza Pourhassan ◽  
Sadigh Raissi ◽  
Arash Apornak
Keyword(s):  
Reliability Analysis ◽  
System Reliability ◽  
System Performance ◽  
Failure Process ◽  
State System ◽  
Failure Behavior ◽  
Simulation Approach ◽  
Critical System ◽  
Content Type ◽  
System Reliability Analysis

PurposeIn some environments, the failure rate of a system depends not only on time but also on the system condition, such as vibrational level, efficiency and the number of random shocks, each of which causes failure. In this situation, systems can keep working, though they fail gradually. So, the purpose of this paper is modeling multi-state system reliability analysis in capacitor bank under fatal and nonfatal shocks by a simulation approach.Design/methodology/approachIn some situations, there may be several levels of failure where the system performance diminishes gradually. However, if the level of failure is beyond a certain threshold, the system may stop working. Transition from one faulty stage to the next can lead the system to more rapid degradation. Thus, in failure analysis, the authors need to consider the transition rate from these stages in order to model the failure process.FindingsThis study aims to perform multi-state system reliability analysis in energy storage facilities of SAIPA Corporation. This is performed to extract a predictive model for failure behavior as well as to analyze the effect of shocks on deterioration. The results indicate that the reliability of the system improved by 6%.Originality/valueThe results of this study can provide more confidence for critical system designers who are engaged on the proper system performance beyond economic design.

Effect of intermetallic compound layer thickness on the shear strength of 1206 chip resistor solder joint

2015 ◽  
Vol 27 (1) ◽  
pp. 52-58 ◽  
Author(s):  
Peter K. Bernasko ◽  
Sabuj Mallik ◽  
G. Takyi
Keyword(s):  
Shear Strength ◽  
Intermetallic Compound ◽  
Solder Joint ◽  
Layer Thickness ◽  
Solder Joints ◽  
Ageing Time ◽  
Circuit Board ◽  
Intermetallic Compound Layer ◽  
Content Type ◽  
Surface Mount

Purpose – The purpose of this paper is to study the effect of intermetallic compound (IMC) layer thickness on the shear strength of surface-mount component 1206 chip resistor solder joints. Design/methodology/approach – To evaluate the shear strength and IMC thickness of the 1206 chip resistor solder joints, the test vehicles were conventionally reflowed for 480 seconds at a peak temperature of 240°C at different isothermal ageing times of 100, 200 and 300 hours. A cross-sectional study was conducted on the reflowed and aged 1206 chip resistor solder joints. The shear strength of the solder joints aged at 100, 200 and 300 hours was measured using a shear tester (Dage-4000PXY bond tester). Findings – It was found that the growth of IMC layer thickness increases as the ageing time increases at a constant temperature of 175°C, which resulted in a reduction of solder joint strength due to its brittle nature. It was also found that the shear strength of the reflowed 1206 chip resistor solder joint was higher than the aged joints. Moreover, it was revealed that the shear strength of the 1206 resistor solder joints aged at 100, 200 and 300 hours was influenced by the ageing reaction times. The results also indicate that an increase in ageing time and temperature does not have much influence on the formation and growth of Kirkendall voids. Research limitations/implications – A proper correlation between shear strength and fracture mode is required. Practical implications – The IMC thickness can be used to predict the shear strength of the component/printed circuit board pad solder joint. Originality/value – The shear strength of the 1206 chip resistor solder joint is a function of ageing time and temperature (°C). Therefore, it is vital to consider the shear strength of the surface-mount chip component in high-temperature electronics.

scholarly journals Revenue diversification and financial sustainability of microfinance institutions

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Peter Nderitu Githaiga
Keyword(s):  
Generalized Method Of Moments ◽  
Financial Sustainability ◽  
Microfinance Institutions ◽  
Revenue Diversification ◽  
Estimation Model ◽  
Data Set ◽  
Content Type ◽  
Method Of Moments Estimation ◽  
The Impact ◽  
Positive Effect

PurposeThis paper aims to investigate whether revenue diversification affects the financial sustainability of microfinance institutions (MFIs).Design/methodology/approachThe study uses a worldwide panel data set of 443 MFIs in 108 countries for the period 2013–2018 and two-step system Generalized Method of Moments estimation model.FindingsThe study finds that revenue diversification has a significant and positive effect on the financial sustainability of MFIs.Practical implicationsThe findings of this study actually offer important managerial and policy lessons on MFIs’ financial sustainability. Microfinance managers and policymakers should consider revenue diversification as a strategy through which MFIs can attain financial sustainability instead of overreliance on donations and government subsidiesOriginality/valueUnlike previous studies that examined revenue diversification in the context of banking firms, this study contributes to literature by examining the impact of revenue diversification of the financial sustainability of MFIs.

Firm-specific internal determinants of profitability performance: an exploratory study of selected life insurance firms in Asia

2018 ◽  
Vol 12 (4) ◽  
pp. 533-550 ◽  
Author(s):  
Rozaimah Zainudin ◽  
Nurul Shahnaz Ahmad Mahdzan ◽  
Ee Shan Leong
Keyword(s):  
Financial Reporting ◽  
Life Insurance ◽  
Exploratory Study ◽  
Panel Study ◽  
Random Effect ◽  
Random Effect Model ◽  
Estimation Model ◽  
Content Type ◽  
Market Expansion ◽  
Insurance Firms

Purpose This study is an exploratory study investigating firm-specific internal factors that influence the profitability performance of selected life insurance firms in eight Asian countries (China, Hong Kong, Taiwan, Singapore, Japan, South Korea, Thailand and Malaysia) from 2008-2014. This paper aims to focus on internal rather than external factors based on the resource-based view suggesting that the internal resources of a firm are key to gaining competitive advantage. Design/methodology/approach The authors used panel data estimation model to test our six hypotheses on these eight selected countries for the period between 2008 and 2014. Findings A random effect model reveals that size, volume of capital and underwriting risk are significantly related to the profitability of Asian life insurance firm, measured as return on assets. Premium growth, asset tangibility and liquidity are insignificant predictors of the profitability performance of these life insurance firms. Practical implications Three implications of this study are that life insurance firms need to proactively tap new business opportunities by attracting younger generation customers via e-marketing technologies; secure larger capital base to finance their market expansion strategies; and focus on intangible resources such as goodwill, brand equity and reputation. Originality/value This study contributes to the literature by conducting an exploratory regional-based panel study of Asian life insurance firms to find common factors that contribute towards profitability. The study is conducted on a collective sample of Asian life insurance firms based on the premise that the firms included in the sample engage in cross-border activities and share the same international financial reporting standards. These commonalities allow us to treat the firms jointly in a somewhat similar Asian macroeconomic environment.

A study on the effects of electrical and thermal stresses on void formation and migration lifetime of Sn3.0Ag0.5Cu solder joints

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yanruoyue Li ◽  
Guicui Fu ◽  
Bo Wan ◽  
Zhaoxi Wu ◽  
Xiaojun Yan ◽  
...  
Keyword(s):  
Solder Joint ◽  
Thermal Stresses ◽  
Solder Joints ◽  
Void Formation ◽  
Model Parameters ◽  
Time To Failure ◽  
Current Crowding ◽  
Theoretical Derivation ◽  
Content Type ◽  
And Migration

Purpose The purpose of this study is to investigate the effect of electrical and thermal stresses on the void formation of the Sn3.0Ag0.5Cu (SAC305) lead-free ball grid array (BGA) solder joints and to propose a modified mean-time-to-failure (MTTF) equation when joints are subjected to coupling stress. Design/methodology/approach The samples of the BGA package were subjected to a migration test at different currents and temperatures. Voltage variation was recorded for analysis. Scanning electron microscope and electron back-scattered diffraction were applied to achieve the micromorphological observations. Additionally, the experimental and simulation results were combined to fit the modified model parameters. Findings Voids appeared at the corner of the cathode. The resistance of the daisy chain increased. Two stages of resistance variation were confirmed. The crystal lattice orientation rotated and became consistent and ordered. Electrical and thermal stresses had an impact on the void formation. As the current density and temperature increased, the void increased. The lifetime of the solder joint decreased as the electrical and thermal stresses increased. A modified MTTF model was proposed and its parameters were confirmed by theoretical derivation and test data fitting. Originality/value This study focuses on the effects of coupling stress on the void formation of the SAC305 BGA solder joint. The microstructure and macroscopic performance were studied to identify the effects of different stresses with the use of a variety of analytical methods. The modified MTTF model was constructed for application to SAC305 BGA solder joints. It was found suitable for larger current densities and larger influences of Joule heating and for the welding ball structure with current crowding.

Pay-performance sensitivity and corporate governance mechanisms: evidence from Tunisia

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Meriem Ghrab ◽  
Marjène Gana ◽  
Mejda Dakhlaoui
Keyword(s):  
Corporate Governance ◽  
Firm Performance ◽  
Pay For Performance ◽  
Simultaneous Equation ◽  
Executive Pay ◽  
Estimation Model ◽  
Content Type ◽  
Explanatory Variables ◽  
Performance Sensitivity ◽  
Ceo Pay

Purpose The purpose of this study is to analyze the CEO compensation sensitivity to firm performance, termed as the pay-for-performance sensitivity (PPS) in the Tunisian context and to test the robustness of this relationship when corporate governance (CG) mechanisms are considered. Design/methodology/approach The consideration of past executive pay as one of the explanatory variables makes this estimation model a dynamic one. Furthermore, to avoid the problem of endogeneity, this study uses the system-GMM estimator developed by Blundell and Bond (1998). For robustness check, this study aims to use a simultaneous equation approach (three-stage least squares [3SLS]) to estimate the link between performance and CEO pay with a set of CG mechanisms to control for possible simultaneous interdependencies. Findings Using a sample of 336 firm-years from Tunisia over the 2009–2015 periods, this study finds strong evidence that the pay-performance relationship is insignificant and negative, and it becomes more negative or remains insignificant after introducing CG mechanisms consistently with the managerial power approach. The findings are robust to the use of alternative performance measures. This study provides new empirical evidence that CEOs of Tunisian firms abuse extracting rents independently of firm performance. Originality/value This study contributes to the unexamined research on PPS in a frontier market. This study also shows the ineffectiveness of the Tunisian CG structure and thus recommends for the legislator to impose a mandatory CG guide.

Surface temperature of electronic assemblies equipped with tilted and low-powered QFN64 subjected to free convection

2017 ◽  
Vol 27 (6) ◽  
pp. 1304-1310 ◽  
Author(s):  
Abderrahmane Baïri ◽  
Clara Ortega Hermoso ◽  
David San Martén Ortega ◽  
Iken Baïri ◽  
Zsolt Peter
Keyword(s):  
Surface Temperature ◽  
Inclination Angle ◽  
Printed Circuit Board ◽  
Electronic Device ◽  
Thermal Design ◽  
Circuit Board ◽  
Content Type ◽  
Printed Circuit ◽  
Volume Method ◽  
Electronic Assemblies

Purpose This work deals with the case of the quad flat non-lead 64 (QFN64) electronic package generating a low power range ranging from 0.01 to 0.1W. It is installed on one side of a printed circuit board (PCB) that can be inclined relative to the horizontal plane with an angle varying between 0° and 90° (horizontal and vertical positions, respectively). The surface temperature of the electronic assembly is subjected to air natural convection. Design/methodology/approach Calculations are done by means of the finite volume method for many configurations obtained by varying the generated power and the inclination angle. Findings The distribution of the surface temperature is determined on all the assembly areas (QFN and PCB). The study shows that the thermal behaviour of the electronic device is influenced by the generated power and the inclination angle. The 3D numerical survey leads to correlations allowing calculation of the average surface temperature in any part of the assembly, according to the power generated by the QFN64 and the inclination angle. Originality/value The proposed accurate correlations are original and unpublished. They optimize the thermal design of the electronic QFN64 package, which is increasingly used in many engineering fields.

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