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Article
Publication date: 4 October 2021

Zhen Pan and Fenglian Sun

The purpose of this paper is to design a novel die-attach composite joint for high-temperature die-attach applications based on transient liquid phase bonding. Moreover, the…

128

Abstract

Purpose

The purpose of this paper is to design a novel die-attach composite joint for high-temperature die-attach applications based on transient liquid phase bonding. Moreover, the microstructure, shear strength, electrical property, thermal conductivity and aging property of the composite joint were investigated.

Design/methodology/approach

The composite joint was made of microporous copper and Cu3Sn. Microporous copper was immersed into liquid Sn to achieve Sn-microporous copper composite structure for die attachment. By the thermo-compression bonding, the Cu3Sn-microporous copper composite joint with a thickness of 100 µm was successfully obtained after bonding at 350 °C for 5 min under a low pressure of 0.6 MPa.

Findings

After thermo-compression bonding, the resulting interconnection could withstand a high temperature of at most 676 °C, with the entire Sn transforming into Cu3Sn with high remelting temperatures. A large shear strength could be achieved with the Cu3Sn-microporous copper in the interconnections. The formed bondlines demonstrated a good electrical and thermal conductivity owing to the large existing amount of copper in the interconnections. Furthermore, the interconnection also exhibited excellent reliability under high temperature aging at 300 °C.

Originality/value

This die-attach composite joint was suitable for power devices operating under high temperatures or other harsh environments.

Details

Soldering & Surface Mount Technology, vol. 34 no. 3
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 27 November 2023

Meng Jiang, Yang Liu, Ke Li, Zhen Pan, Quan Sun, Yongzhe Xu and Yuan Tao

The purpose of this paper is to study the reliability of sintered nano-silver joints on bare copper substrates during high-temperature storage (HTS).

136

Abstract

Purpose

The purpose of this paper is to study the reliability of sintered nano-silver joints on bare copper substrates during high-temperature storage (HTS).

Design/methodology/approach

In this study, HTS at 250 °C was carried out to investigate the reliability of nano-silver sintered joints. Combining the evolution of the microstructure and shear strength of the joints, the degradation mechanisms of joints performance were characterized.

Findings

The results indicated that the degradation of the shear properties of sintered nano-silver joints on copper substrates was attributed to copper oxidation at the silver/copper interface and interdiffusion of interfacial elements. The joints decreased by approximately 57.4% compared to the original joints after aging for 500 h. In addition, severe coarsening of the silver structure was also an important cause for joints failure during HTS.

Originality/value

This paper provides a comparison of quantitative and mechanistic evaluation of sintered silver joints on bare copper substrates during HTS, which is of great importance in promoting the development of sintered silver technology.

Details

Soldering & Surface Mount Technology, vol. 36 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 14 August 2021

Risheng Long, Chao Zhao, Zhihao Jin, Yimin Zhang, Zhen Pan, Shaoni Sun and Weihua Gao

The purpose of this paper is to reveal the friction and wear performance of grooves textured cylindrical roller thrust bearings with different groove dimensions under starved…

211

Abstract

Purpose

The purpose of this paper is to reveal the friction and wear performance of grooves textured cylindrical roller thrust bearings with different groove dimensions under starved lubrication.

Design/methodology/approach

The groove dimensions include: width of grooves (WOG, 50 µm, 100 µm and 150 µm), depth of grooves (DPOG, 7 µm, 11 µm and 15 µm) as well as groove deflection angle (GDA, 45°). A fiber laser marking system was used to prepare groove patterns on the raceways of shaft washers. The friction and wear properties of grooves textured bearings were researched through a vertical universal wear test rig using a customized roller bearing tribo-pair under starved lubrication. Static finite element analyses were conducted to reveal their surface stresses. Through the comprehensive comparison and analyses, the influence mechanism of grooves on the tribological behavior of cylindrical roller thrust bearings was proposed and discussed.

Findings

When grooves textured bearings run under starved lubrication, their average coefficients of friction (COFs) and wear losses are all significantly reduced and much lower than those of smooth group. The influence of DPOG on the COF curves is significant, while the influence of WOG on the COF curves is a little weak. The influence of groove dimensions on the surface stresses of grooves textured bearings is weak, whether the WOG or DPOG. In this work, when the WOG is 100 µm and the DPOG is 15 µm, its average COF and wear loss are both the lowest, 0.0066 and 0.61 mg, respectively. Compared with the data of smooth group, its friction coefficient is reduced by 75.3% and its mass loss is reduced by 95.8%, showing a significant improvement in this condition.

Originality/value

This work can provide a valuable reference for the raceway design and reliability optimization of rolling element bearings.

Details

Industrial Lubrication and Tribology, vol. 73 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 14 April 2022

Meng Xu, Fenglian Sun, Zhen Pan and Yang Liu

The purpose of this paper is to study the temperature cycling reliability of Sn-5Sb-0.5Cu-0.1Ni-0.5Ag/Cu micro solder joints compared with Sn-5Sb/Cu and SAC305/Cu micro solder…

129

Abstract

Purpose

The purpose of this paper is to study the temperature cycling reliability of Sn-5Sb-0.5Cu-0.1Ni-0.5Ag/Cu micro solder joints compared with Sn-5Sb/Cu and SAC305/Cu micro solder joints, which has important engineering and theoretical significance for the research of micro solder joint reliability. This paper also aims to provide guidance for the selection of solder for third-generation semiconductor power device packaging.

Design/methodology/approach

The shear strength, plasticity, bulk solder hardness and creep performance of three kinds of micro solder joints before and after temperature cycling were studied by nanoindentation and micro shear experiments. Scanning electron microscopy and energy dispersive spectrometry were used to analyze the fracture mode, fracture position and compound composition of the solder joints.

Findings

The bulk solder hardnesses and shear strengths of Sn-5Sb-0.5Cu-0.1Ni-0.5Ag/Cu solder joints were higher than those of Sn-5Sb/Cu and SAC305/Cu solder joints before and after temperature cycling. The indentation depth, creep displacement and creep rate of bulk solders of Sn-5Sb-0.5Cu-0.1Ni-0.5Ag/Cu solder joints were the smallest compared with those of Sn-5Sb/Cu and SAC305/Cu solder joints after the same number of cycles. In addition, the fracture mode and fracture position of the micro solder joints changed before and after temperature cycling.

Originality/value

A new type of solder was developed with excellent temperature cycling performance.

Details

Soldering & Surface Mount Technology, vol. 35 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 14 May 2021

F Sun, Zhen Pan, Yang Liu, Xiang Li, Haoyu Liu and Wenpeng Li

The purpose of this paper is to quickly manufacture full Cu3Sn-microporous copper composite joints for high-temperature power electronics applications and study the microstructure…

227

Abstract

Purpose

The purpose of this paper is to quickly manufacture full Cu3Sn-microporous copper composite joints for high-temperature power electronics applications and study the microstructure evolution and the shear strength of Cu3Sn at different bonding times.

Design/methodology/approach

In this paper, a novel structure of Cu/composite solder sheet/Cu was designed. The composite solder sheet was made of microporous copper filled with Sn. The composite joint was bonded by thermo-compression bonding under pressure of 0.6 MPa at 300°C. The microstructure evolution and the growth behavior of Cu3Sn at different bonding times were observed by electron microscope and metallographic microscope. The shear strength of the joint was measured by shear machine.

Findings

At initial bonding stage the copper atoms in the substrate and the copper atoms in the microporous copper dissolved into the liquid Sn. Then the scallop-liked Cu6Sn5 phases formed at the interface of liquid Sn/microporous copper and liquid Sn/Cu substrates. During the liquid Sn changing to Cu6Sn5 phases, Cu3Sn phases formed and grew at the interface of Cu6Sn5/Cu substrates and Cu6Sn5/microporous copper. After that the Cu3Sn phases continued to grow and the Cu3Sn-microporous copper composite joint with a thickness of 100 µm was successfully obtained. The growth rule of Cu3Sn was parabolic growth. The shear strength of the composite joints was about 155 MPa.

Originality/value

This paper presents a novel full Cu3Sn-microporous copper composite joint with high shear strength for high-temperature applications based on transient liquid phase bonding. The microstructure evolution and the growth behavior of Cu3Sn in the composite joints were studied. The shear strength and the fracture mechanism of the composite joints were studied.

Details

Soldering & Surface Mount Technology, vol. 33 no. 5
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 6 March 2017

Xiuchen Wang, Yaping Li, Ying Su, Zhen Pan and Zhe Liu

The three-dimensional arrangement structure of the conductive fiber is an important factor of the shielding effectiveness of the electromagnetic shielding fabric (EMSF). However…

265

Abstract

Purpose

The three-dimensional arrangement structure of the conductive fiber is an important factor of the shielding effectiveness of the electromagnetic shielding fabric (EMSF). However, until now, the three-dimensional arrangement structure has not been described because of the complex structure, which leads to many difficulties for the subsequent analysis of the electromagnetic characteristics. Therefore, the purpose of this paper is to propose a feature extraction method to describe the arrangement structure of the conductive fiber based on the three-dimensional calibration and image processing technology, providing a new idea for the above problem.

Design/methodology/approach

First, the three-dimensional positions of the conductive fibers in the EMSF are calibrated using the VHX-600 3D digital microscope and the MATLAB7.5 software. The arrangement characteristics of the conductive fibers are analyzed, and equivalent twist, cross-sectional content, and average angle of a single fiber are proposed to describe the arrangement characteristic of the conductive fiber. Then, a digital description model of the conductive fiber is constructed according to the feature parameters and its three-dimensional structures are reproduced using CATIA. Finally, the reliability of the model is verified by an FDTD example, and the significance and application of the model are given.

Findings

The proposed method can provide the feature extraction and description for the complex spatial three-dimensional arrangement structure of conductive fibers. The feature parameters can reflect different micro arrangement features of the conductive fiber. The proposed idea and method can provide a solid foundation for subsequent studies of the electromagnetic properties of the EMSF.

Originality/value

The study in this paper is of great significance and academic value. This paper provides a new three-dimensional calibration method and constructs multiple feature parameters to describe the complex three-dimensional arrangement structure, providing a new effective method to overcome the problem of the conductive fiber description. The proposed method provides an important basis for the shielding mechanism, transmission characteristics, electromagnetic calculation and product design, and woven technology of the EMSF.

Details

International Journal of Clothing Science and Technology, vol. 29 no. 1
Type: Research Article
ISSN: 0955-6222

Keywords

Available. Open Access. Open Access
Article
Publication date: 18 July 2024

Bo Zhang, Shengjun Wang and Ruixue Zhou

This paper examines the impact of corporate digital transformation on employee satisfaction. Therefore, this study extends our understanding of the economic consequences of…

992

Abstract

Purpose

This paper examines the impact of corporate digital transformation on employee satisfaction. Therefore, this study extends our understanding of the economic consequences of corporate digital transformation from employees’ perspectives.

Design/methodology/approach

The data used to construct our main proxy of employee satisfaction are collected from Kanzhun.com, which provides reviews by rank-and-file employees on their employers. This study uses a large sample of Chinese firms and adopts various empirical methods to examine the impact of digital transformation on employee satisfaction.

Findings

We find a significant positive relationship between corporate digital transformation and employee satisfaction. Moreover, we document that the relationship between corporate digital transformation and employee satisfaction is more pronounced in firms with higher labor intensity and in state-owned enterprises (SOE).

Research limitations/implications

One significant limitation is that corporate digital transformation is constructed based on word frequency analysis. This approach may be influenced by variations in corporate disclosure practices and might not accurately capture the true extent of corporate digital transformation. This limitation is not only present in our research but is also pervasive in many other studies that utilize similar methodologies. Therefore, our results should be interpreted with this caveat in mind.

Practical implications

Our study suggests that corporate digital transformation enhances employee satisfaction, providing direct evidence for managers and regulators to promote corporate digital transformation. Through digital transformation, companies can not only improve operational efficiency but also foster employee satisfaction. This dual benefit underscores the importance of investing in corporate digital transformation for long-term success.

Social implications

Our study suggests that corporate digital transformation enhances employee satisfaction, providing direct evidence for managers and regulators to promote corporate digital transformation. Through digital transformation, companies can not only improve operational efficiency but also foster employee satisfaction. This dual benefit underscores the importance of investing in corporate digital transformation for long-term success.

Originality/value

Our study contributes to the literature on the economic consequences of corporate digital transformation and extends existing research on the determinants of employee satisfaction. Additionally, it provides a novel measurement of employee satisfaction for a large sample of Chinese firms.

Details

China Accounting and Finance Review, vol. 26 no. 4
Type: Research Article
ISSN: 1029-807X

Keywords

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Article
Publication date: 10 May 2019

Ruoxuan Liu, Sean Mcginty, Fangsen Cui, Xiaoyu Luo and Zishun Liu

The purpose of this paper is to demonstrate the feasibility of using shape memory polymer (SMP) for developing vascular stent. In particular, the expansion performance is analyzed…

514

Abstract

Purpose

The purpose of this paper is to demonstrate the feasibility of using shape memory polymer (SMP) for developing vascular stent. In particular, the expansion performance is analyzed through extensive modeling and simulation.

Design/methodology/approach

Firstly, the authors construct the model geometry and propose a constitutive model to describe the deformation of the stent due to the expansion process. The authors then simulate the expansion process under varying conditions, including different heating rates and recovery temperatures. Finally, the authors analyze the radial strength of the SMP stent.

Findings

A less invasive and stable expansion performance of the SMP stent is confirmed by the simulation method. A fitting function of the expansion process is proposed based on the characteristics of the SMP.

Research limitations/implications

The effects of dynamic blood flow on the SMP stent is ignored. A fluid-structure interaction analysis may need to be considered to give a more accurate description of the behaviour of the SMP stent.

Practical implications

The findings will provide guidance for the rational design and application of SMP stents.

Social implications

The work will provide guidance for the new generation stent design.

Originality/value

This is the first time that the expansion performance of a SMP stent has been analyzed both qualitatively and quantitatively through modelling and simulation.

Details

Engineering Computations, vol. 36 no. 8
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 3 May 2022

Zhen Chen, Yaqi Zhao, Xia Zhou, Shengyue Hao and Jin Li

Human–robot collaboration (HRC) is an emerging research field for the construction industry along with construction robot adoption, but its implementation remains limited in…

905

Abstract

Purpose

Human–robot collaboration (HRC) is an emerging research field for the construction industry along with construction robot adoption, but its implementation remains limited in construction sites. This paper aims to identify critical risk factors and their interactions of HRC implementation during engineering project construction.

Design/methodology/approach

Literature research, expert interviews, a questionnaire survey and a social network analysis (SNA) method were used. First, literature research and expert interviews were employed to identify risk factors of HRC implementation and preliminarily understand factor interactions. Second, a questionnaire survey was conducted to determine the degree of interactions between risk factors. Third, based on the data collected from the questionnaire survey, SNA metrics were used to find critical risk factors and critical interactions.

Findings

The critical risk factors consist of robot technology reliability, robot-perceived level, conflict between designers and users of construction robots, organisational culture, organisational strength, project cost requirements, changeability of project construction, project quality requirements and project safety requirements. The interactions between risk factors are strong and complex. Robot technology risk factors were relatively fundamental risk factors, and project risk factors had a direct influence on the risk of HRC implementation. The implementation cost of HRC was not identified as a critical risk factor. Individual risk factors could be mitigated by improving technical and organisational factors.

Originality/value

This paper contributes to the body of knowledge in the field of both HRC behaviours and its risk management in construction project management. Identifying the critical risk factors and their interactions of HRC implementation in the construction industry and introducing social network theory to the research on critical risk factors are the innovations of this paper. The findings and proposed suggestions could help construction professionals to better understand the HRC risk factors and to manage the risk of HRC implementation more effectively.

Details

Engineering, Construction and Architectural Management, vol. 30 no. 7
Type: Research Article
ISSN: 0969-9988

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Article
Publication date: 6 February 2024

Jing Song

This study aims to examine why women transition from wage work to self-employed entrepreneurship, the seemingly insecure and unruly economic sector compared with the stable iron…

122

Abstract

Purpose

This study aims to examine why women transition from wage work to self-employed entrepreneurship, the seemingly insecure and unruly economic sector compared with the stable iron rice bowl and the fancy spring rice jobs.

Design/methodology/approach

Based on in-depth interviews in Zhejiang, the entrepreneurial hotbed in coastal China, this study examines the experiences of self-employed female entrepreneurs who used to work in the iron rice bowl and the spring rice jobs and explores their nonconventional career transition and its gendered implications.

Findings

This study finds that these women quit their previous jobs to escape from gendered suppression in wage work where their femininity was stereotyped, devalued or disciplined. By working for themselves, these women embrace a rubber rice bowl that allows them to improvise different forms of femininity that are better rewarded and recognized.

Originality/value

The study contributes to studies on gender and work by framing femininity as a fluid rather than a fixed set of qualities and fills the research gap by illustrating women’s agency in reacting to gender expectations in certain workplaces. The study develops a new concept of rubber rice bowl to describe how entrepreneurship, a seemingly women-unfriendly sphere, attracts women by allowing them to comply with, resist, or improvise normative gender expectations.

Details

Gender in Management: An International Journal, vol. 39 no. 7
Type: Research Article
ISSN: 1754-2413

Keywords

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