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Microelectronics International, vol. 40 no. 2
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 23 September 2021

Jianing Wang, Jieshi Chen, Zhiyuan Zhang, Peilei Zhang, Zhishui Yu and Shuye Zhang

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…

476

Abstract

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.

Details

Soldering & Surface Mount Technology, vol. 34 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 12 September 2023

Yuzhu Han, Jieshi Chen, Shuye Zhang and Zhishui Yu

This paper aims to investigate the effect of solder composition and roughness on early wetting behavior and interfacial reaction under atmospheric conditions.

106

Abstract

Purpose

This paper aims to investigate the effect of solder composition and roughness on early wetting behavior and interfacial reaction under atmospheric conditions.

Design/methodology/approach

High-speed photography is used to observe the early wetting and spreading process of the solder on the substrate in real time. The morphology of intermetallic compounds (IMCs) was observed by scanning electron microscopy, and the composition of IMCs micro bumps was determined by energy dispersive spectroscopy.

Findings

With a roughness range of 0.320–0.539 µm, the solder is distributed in an elliptical trilinear pattern along the grinding direction. With a roughness range of 0.029–0.031 µm, the solder spreads in the direction of grinding and perpendicular, forming a perfect circle (except in the case of Sn63Pb37 solder). The effect of three types of solder on early wettability is Sn63Pb37 > Sn96.5Ag3Cu0.5 > Sn. The wetting behavior is consistent with the Rn∼t model. The rapid spreading stage (Stage I) is controlled by the interfacial reaction with n1 values between 2.4 and 4. The slow spreading stage (stage II) is controlled by diffusion with n2 values between 4 and 6.7. The size of Cu6Sn5 formed on a rough substrate is greater than that produced on a smooth substrate.

Originality/value

Investigating the effect of solder composition and roughness on early wettability. This will provide a powerful guide in the field of soft brazing.

Details

Soldering & Surface Mount Technology, vol. 35 no. 5
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 8 August 2024

Yan Pan, Shuye Zhang, Pengli Zhu and Kyung W. Paik

The study aims to ascertain the influence of solder conductive particle types and substrate widths on the current carrying capability of flex-on-board (FOB) assemblies. By…

32

Abstract

Purpose

The study aims to ascertain the influence of solder conductive particle types and substrate widths on the current carrying capability of flex-on-board (FOB) assemblies. By comparing Sn58Bi and SAC305 particles and varying substrate widths, the research sought to provide insights into the stability and performance of solder joints under different scenarios, particularly in high-power applications.

Design/methodology/approach

The study used a comprehensive design/methodology, encompassing the investigation of solder conductive particle types (Sn58Bi and SAC305) and substrate widths on the current carrying capability of FOB assembly. Stable solder joints were obtained by manipulating the curing speed of anisotropic conductive films for both particle types. Various tests were conducted, including current carrying capability assessments under differing conditions.

Findings

The study revealed that larger substrate widths yielded higher current carrying capability due to increased contact area and reduced contact resistance. Notably, solder joints remained stable beyond the solder melting temperature due to encapsulation by cured epoxy resin. SAC305 solder joints exhibited superior current carrying capability over Sn58Bi in continuous high-voltage conditions. The results emphasized the stability of SAC305 solder joints and their suitability for robust interconnections in high-power FOB assemblies.

Originality/value

This study contributes by offering a comprehensive assessment of the impact of solder particle types and substrate widths on solder joint performance in FOB assemblies. The finding that SAC305 joints outperform Sn58Bi under continuous high-voltage conditions adds significant value. Moreover, the observation of stable solder joints beyond solder melting temperature due to resin encapsulation introduces a novel aspect to solder joint reliability. These insights provide valuable guidance for designing robust and high-performance interconnections in demanding applications.

Details

Soldering & Surface Mount Technology, vol. 36 no. 5
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 4 December 2023

Yang Liu, Xin Xu, Shiqing Lv, Xuewei Zhao, Yuxiong Xue, Shuye Zhang, Xingji Li and Chaoyang Xing

Due to the miniaturization of electronic devices, the increased current density through solder joints leads to the occurrence of electromigration failure, thereby reducing the…

145

Abstract

Purpose

Due to the miniaturization of electronic devices, the increased current density through solder joints leads to the occurrence of electromigration failure, thereby reducing the reliability of electronic devices. The purpose of this study is to propose a finite element-artificial neural network method for the prediction of temperature and current density of solder joints, and thus provide reference information for the reliability evaluation of solder joints.

Design/methodology/approach

The temperature distribution and current density distribution of the interconnect structure of electronic devices were investigated through finite element simulations. During the experimental process, the actual temperature of the solder joints was measured and was used to optimize the finite element model. A large amount of simulation data was obtained to analyze the neural network by varying the height of solder joints, the diameter of solder pads and the magnitude of current loads. The constructed neural network was trained, tested and optimized using this data.

Findings

Based on the finite element simulation results, the current is more concentrated in the corners of the solder joints, generating a significant amount of Joule heating, which leads to localized temperature rise. The constructed neural network is trained, tested and optimized using the simulation results. The ANN 1, used for predicting solder joint temperature, achieves a prediction accuracy of 96.9%, while the ANN 2, used for predicting solder joint current density, achieves a prediction accuracy of 93.4%.

Originality/value

The proposed method can effectively improve the estimation efficiency of temperature and current density in the packaging structure. This method prevails in the field of packaging, and other factors that affect the thermal, mechanical and electrical properties of the packaging structure can be introduced into the model.

Details

Soldering & Surface Mount Technology, vol. 36 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 17 February 2023

Xionghui Cai, Aixia Zhai, Chenglong Zhou and Kyung-Wook Paik

The purpose of this study is to investigate the reliability of flex-on-board (FOB) interconnection connected with an anisotropic conductive paste (ACP), which is prepared by…

103

Abstract

Purpose

The purpose of this study is to investigate the reliability of flex-on-board (FOB) interconnection connected with an anisotropic conductive paste (ACP), which is prepared by dispersing nickel balls in the epoxy-curing system.

Design/methodology/approach

Differential scanning calorimetry was used to evaluate the curing characteristics of the paste. And the contact resistances of bonding joints and 90º peel adhesion were tested before and after high temperature and high humidity test (85°C, 85% humidity), thermal cycling (−45°C∼125°C, 30min/cycle) and pressure cooker test (PCT, 121°C, 100% humidity 2 atm) to evaluate the flex on board (FOB) interconnection reliability.

Findings

It is found that FOB test vehicles have been successfully bonded by using ACP for the first time. And the ACP bonding joint of FOB has good reliability and can meet the requirements of FOB interconnection. Compared with conventional anisotropic conductive film (ACF), this ACP interconnection provides higher adhesion strength, higher joint current carrying capability and higher reliability performance and lower cost for FOB interconnection.

Originality/value

ACP is applied in the interconnection of FOB. It has the higher reliability performance and lower cost for than the conventional ACF.

Details

Microelectronics International, vol. 40 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Available. Open Access. Open Access
Article
Publication date: 4 July 2024

Songtao Qu, Qingyu Shi, Gong Zhang, Xinhua Dong and Xiaohua Xu

This study aims to address the problem of low-temperature wave soldering in industry production with Sn-9Zn-2.5 Bi-1.5In alloys and develop qualified process parameters. Sn–Zn…

445

Abstract

Purpose

This study aims to address the problem of low-temperature wave soldering in industry production with Sn-9Zn-2.5 Bi-1.5In alloys and develop qualified process parameters. Sn–Zn eutectic alloys are lead-free solders applied in consumer electronics due to their low melting point, high strength, and low cost. In the electronic assembly industry, Sn–Zn eutectic alloys have great potential for use.

Design/methodology/approach

This paper explored developing and implementing process parameters for low-temperature wave soldering of Sn–Zn alloys (SN-9ZN-2.5BI-1.5 In). A two-factor, three-level design of the experiments experiment was designed to simulate various conditions parameters encountered in Sn–Zn soldering, developed the nitrogen protection device of waving soldering and proposed the optimal process parameters to realize mass production of low-temperature wave soldering on Sn–Zn alloys.

Findings

The Sn-9Zn-2.5 Bi-1.5In alloy can overcome the Zn oxidation problem, achieve low-temperature wave soldering and meet IPC standards, but requires the development of nitrogen protection devices and the optimization of a series of process parameters. The design experiment reveals that preheating temperature, soldering temperature and flux affect failure phenomena. Finally, combined with the process test results, an effective method to support mass production.

Research limitations/implications

In term of overcome Zn’s oxidation characteristics, anti-oxidation wave welding device needs to be studied. Various process parameters need to be developed to achieve a welding process with lower temperature than that of lead solder(Sn–Pb) and lead-free SAC(Sn-0.3Ag-0.7Cu). The process window of Sn–Zn series alloy (Sn-9Zn-2.5 Bi-1.5In alloy) is narrow. A more stringent quality control chart is required to make mass production.

Practical implications

In this research, the soldering temperature of Sn-9Zn-2.5 Bi-1.5In is 5 °C and 25 °C lower than Sn–Pb and Sn-0.3Ag-0.7Cu(SAC0307). To the best of the authors’ knowledge, this work was the first time to apply Sn–Zn solder alloy under actual production conditions on wave soldering, which was of great significance for the study of wave soldering of the same kind of solder alloy.

Social implications

Low-temperature wave soldering can supported green manufacturing widely, offering a new path to achieve carbon emissions for many factories and also combat to international climate change.

Originality/value

There are many research papers on Sn–Zn alloys, but methods of achieving low-temperature wave soldering to meet IPC standards are infrequent. Especially the process control method that can be mass-produced is more challenging. In addition, the metal storage is very high and the cost is relatively low, which is of great help to provide enterprise competitiveness and can also support the development of green manufacturing, which has a good role in promoting the broader development of the Sn–Zn series.

Details

Soldering & Surface Mount Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 15 November 2024

Ji Huang, Monica Jurin, On Kit Tam, Hassan F. Gholipour and Chao Ren

This study evaluates the evolution from traditional to nontraditional financial intermediation (NTFI) in Chinese commercial banks from 2006 to 2021, analysing its impact on bank…

29

Abstract

Purpose

This study evaluates the evolution from traditional to nontraditional financial intermediation (NTFI) in Chinese commercial banks from 2006 to 2021, analysing its impact on bank performance and risk.

Design/methodology/approach

Accounting measures are used to construct granular activity data, and factor analysis is employed to develop a financial intermediation evolution (FIE) index. The fully modified OLS (FMOLs) estimator is used for nonstationary data analysis, and difference-in-differences (DID) analysis is used for robustness check.

Findings

Chinese banks exhibit unique evolution in financial intermediation compared to developed economies, with greater inter-bank variations over time than intra-bank differences. From 2006 to 2017, three paths were identified: Investment, Fee and Repo models, with a fourth path (the Investment2 model) emerging post-2017. Only the Repo model enhances bank returns (ROA & ROE), while shifts towards NTFI increase liquidity and leverage risks across all models. The evolution of bank business models and their consequent implications on performance and risks are influenced by regulatory objectives and banks’ endeavours in regulatory arbitrage.

Practical implications

Major stakeholders in the banking sector can gain a better understanding of financial intermediation and associated market behaviour, performance and risks, with significant implications for banking regulations and crisis management.

Originality/value

This study provides the first comprehensive overview of the evolution of Chinese commercial banks’ financial intermediation activities over an extended period, uncovering the unique characteristics distinct from the developed economies.

Details

Journal of Accounting Literature, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0737-4607

Keywords

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Article
Publication date: 8 November 2022

Ernesto Tavoletti and Vas Taras

This study aims to offer a bibliometric analysis of the already substantial and growing literature on global virtual teams (GVTs).

651

Abstract

Purpose

This study aims to offer a bibliometric analysis of the already substantial and growing literature on global virtual teams (GVTs).

Design/methodology/approach

Using a systematic literature review approach, it identifies all articles in the Web of Science from 1999 to 2021 that include the term GVTs (in the title, the abstract or keywords) and finds 175 articles. The VOSviewer software was applied to analyze the bibliometric data.

Findings

The analysis revealed three dialogizing research clusters in the GVTs literature: a pioneering management information systems and organizational cluster, a general management cluster and a growing international management and behavioural studies cluster. Furthermore, it highlights the most cited articles, authors, journals and nations, and the network of strong and weak links regarding co-authorships and co-citations. Additionally, this study shows a change in research patterns regarding topics, journals and disciplinary approaches from 1999 to 2021. Finally, the analysis illustrates the position and centrality in the network of the most relevant actors.

Practical implications

The findings can guide management practitioners, educators and researchers to the most meaningful clusters of publications on GVTs, and help navigate and make sense of the vast body of the available literature. The importance of GVTs has been growing in the past two decades, and Covid-19 has accelerated the trend.

Originality/value

This study provides an updated and comprehensive systematic literature review on GVTs. To the best of the authors’ knowledge, it is also the first systematic literature review and bibliometry on GVTs. It concludes by suggesting future research paths.

Details

Management Research Review, vol. 46 no. 8
Type: Research Article
ISSN: 2040-8269

Keywords

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