Abstract
Purpose
This paper aims to assess precise correlations between intermetallic compounds (IMCs) microstructure evolutions and the reliability of micro-joints with a Cu/SAC305solder/Ni structure using thermal shock (TS) tests.
Design/methodology/approach
This paper uses 200-µm pitch silicon flip chips with nickel (Ni) pads and stand-off height of approximately 60 µm, assembled on substrates with copper (Cu) pads. After assembly, the samples were subjected to air-to-air thermal shock testing from 55 to 125 per cent. The transfer time was less than 5 s, and the dwell time at each temperature extreme was 15 min. To investigate the microstructure evolution and crack growth, two samples were removed from the thermal shock chamber at 0, 400, 1,200, 2,000, 5,800 and 7,000 cycles.
Findings
The results showed that one (Cu, Ni)6Sn5/(Ni, Cu)3Sn4 dual-layer structure formed at the Ni pad interface of chip side dominates the micro-joints failure. This is because substantial (Ni, Cu)3Sn4 grain boundaries provide a preferential pathway for the catastrophic crack growth. Other IMCs microstructure evolutions that cause the prevalent joints failure as previously reported, i.e. thickened interfacial (Cu, Ni)6Sn5 and Ni3P layer, and coarsened IMCs inside the solder matrix, only contributed to the occurrence of fine cracks. Moreover, the typical interfacial IMCs spalling triggered by thermally induced stress did not take place in this study, showing a positive impact in the micro-joint reliability.
Originality/value
As sustained trends toward multi-functionality and miniaturization of microelectronic devices, the joints size is required to be constantly scaled down in advanced packages. This arises a fact that the reliability of small-size joints is more sensitive to the IMCs because of their high volume proportion and greatly complicated microstructure evolutions. This paper evaluated precise correlations between IMCs microstructure evolutions and the reliability of micro-joints with a Cu/SAC305solder/Ni structure using TS tests. It found that one (Cu, Ni)6Sn5/(Ni, Cu)3Sn4 dual-layer structure formed at the Ni pad interface dominate the micro-joints failure, whereas other IMCs microstructure evolutions that cause the prevalent joints failure exhibited nearly negligible effects.
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Yixuan Li, Yanfeng Chen, Bo Zhang, Dongyuan Qiu, Fan Xie and Chao Cheng
The purpose of this paper is to find a simpler model for the reactance components in the high-frequency range on the premise of ensuring the accuracy.
Abstract
Purpose
The purpose of this paper is to find a simpler model for the reactance components in the high-frequency range on the premise of ensuring the accuracy.
Design/methodology/approach
In this paper, based on the fractional calculus theory and the traditional integer-order model, a reactance model suitable for high frequency is constructed, and the mutation cross differential evolution algorithm is used to identify the parameters in the model.
Findings
By comparing the integer-order model, high-frequency fractional-order model and the actual impedance characteristic curve of inductance and capacitance, it is verified that the proposed model can more accurately reflect the high-frequency characteristics of inductance and capacitance. The simulation and experimental results show that the oscillator constructed based on the proposed model can analyze the frequency and output waveform of the oscillator more accurately.
Originality/value
The model proposed in this paper has a simple structure and contains only two parameters to be identified. At the same time, the model has high precision. The fitting errors of impedance curve and phase-frequency characteristic curve are less than 5%. Therefore, the proposed model is helpful to improve the simplicity and accuracy of circuit system analysis and design.
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Wang Zhizhong, Han Chao, Guosheng Huang, Han Bin and Han Bin
The deposition of particles onto a substrate during the cold spraying (CS) process relies on severe plastic deformation, so there are various micro-defects induced by insufficient…
Abstract
Purpose
The deposition of particles onto a substrate during the cold spraying (CS) process relies on severe plastic deformation, so there are various micro-defects induced by insufficient deformation and severe crushing. To solve the problems, many post-treat techniques have been used to improving the quality by eliminating the micro-defects. This paper aims to help scholars and engineers in this field a better and systematic understand of CS technology by summarizing the post-treatment technologies that have been investigated recently years.
Design/methodology/approach
This review summarizes the types of micro-defects and introduces the effect of micro-defects on the properties of CS coating/additive manufactured, illustrates the post-treatment technologies and its effect on the microstructure and performances, and finally outlooks the future development trends of post-treatments for CS.
Findings
There are significant discoveries in post-treatment technology to change the performance of cold spray deposits. There are also many limitations for post-treatment methods, including improved performance and limitations of use. Thus, there is still a strong requirement for further improvement. Hybrid post-treatment may be a more ideal method, as it can eliminate more defects than a single method. The proposed ultrasonic impact treatment could be an alternative method, as it can densify and flatten the CS deposits.
Originality/value
It is the first time to reveal the influence factors on the performances of CS deposits from the perspective of microdefects, and proposed corresponding well targeted post-treatment methods, which is more instructive for improving the performances of CS deposits.
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The purpose of this paper is to provide the historical background of genealogical records and analyze the value of Chinese genealogical research through the study of names and…
Abstract
Purpose
The purpose of this paper is to provide the historical background of genealogical records and analyze the value of Chinese genealogical research through the study of names and genealogical resources.
Design/methodology/approach
The paper examines the historical evolution and value of Chinese genealogical records, with the focus on researching the Islamic Chinese names used by the people living in Guilin. The highlight of this paper includes the analysis and evolution of the Islamic Chinese names commonly adopted by the local people in Guilin. It concludes with the recommendations on emphasizing and making the best use of genealogical records to enhance the research value of Chinese overseas studies.
Findings
The paper covers the history of Islam and describes how the religion was introduced into China, as well as Muslims' ethnicity and identity. It also places focus on the importance of building a research collection in Asian history and Chinese genealogy.
Research limitations/implications
This research study has a strong subject focus on Chinese genealogy, Asian history, and Islamic Chinese surnames. It is a narrow field that few researchers have delved into.
Practical implications
The results of this study will assist students, researchers, and the general public in tracing the origin of their surnames and developing their interest in the social and historical value of Chinese local history and genealogies.
Social implications
The study of Chinese surnames is, by itself, a particular field for researching the social and political implications of contemporary Chinese society during the time the family members lived.
Originality/value
Very little research has been done in the area of Chinese local history and genealogy. The paper would be of value to researchers such as historians, sociologists, ethnologists and archaeologists, as well as students and anyone interested in researching a surname origin, its history and evolution.
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Lawrence Hoc Nang Fong, Hongwei He, Melody Manchi Chao, Galli Leandro and David King
The purpose of this study is to understand Chinese consumers’ responses to ethnically tailored hotel services from the theoretical perspective of cultural essentialism.
Abstract
Purpose
The purpose of this study is to understand Chinese consumers’ responses to ethnically tailored hotel services from the theoretical perspective of cultural essentialism.
Design/methodology/approach
Data collection was conducted through an online survey with Chinese respondents. Hierarchical moderated regression was performed to analyze the data.
Findings
The results show a positive relationship between cultural essentialism and consumer responses to hotel services that are tailored to their culture. Furthermore, the findings show that prior service satisfaction does not only positively influence the consumer responses, but also amplifies the link between cultural essentialism and the consumer responses.
Practical implications
Hoteliers are recommended to consider the cultural essentialism of Chinese consumers when adaptive services are introduced. Hotel services that are tailored to Chinese culture is a viable strategy if most Chinese customers are cultural essentialists.
Originality/value
This study adds knowledge to the hospitality scholarship by introducing cultural essentialism and demonstrating its role in influencing consumer preferences for familiarity as opposed to exotic hotel services. Furthermore, the moderating role of service satisfaction extends the consumer behavior literature.
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Shengyang Sun, Chao Zhang and Ruifa Hu
The negative externalities of pesticide overuse increasingly concern the public. However, little empirical evidence has been provided for pesticide overuse and the relationship…
Abstract
Purpose
The negative externalities of pesticide overuse increasingly concern the public. However, little empirical evidence has been provided for pesticide overuse and the relationship between the governmental agricultural extension system reforms and pesticide use in grain production from a nationwide perspective. The purpose of this paper is to estimate the productive effect and overuse of pesticides, and it also investigates the effect of the governmental agricultural extension system reforms on pesticide expenditure in rice, maize and wheat production in China.
Design/methodology/approach
A two-equation system model consisting of an exponential-specific damage-control production function and a pesticide use function is applied to the provincial-level data during the period 1985–2016.
Findings
While pesticide expenditure significantly increases grain productivity, the actual pesticide expenditure exceeds the economically optimal level. The commercialization reform of the governmental agricultural extension system contributed to the increase in pesticide expenditure. Moreover, the de-commercialization reform of the governmental agricultural extension system plays a limited role in pesticide reduction. Price fluctuations for grain and pesticide also impose significant effects on pesticide expenditure.
Originality/value
This study has two important policy implications for pesticide reduction in China. It is urgent to specify the functions of the governmental agricultural extension system, and encourage the development of the socialized agricultural technology service. More efforts should also be made to remove the bureaucratic intervention on the pricing mechanism of grain product and pesticide.
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Kaiying Kang, Jialiang Xie, Xiaohui Liu and Jianxiang Qiu
Experts may adjust their assessments through communication and mutual influence, and this dynamic evolution relies on the spread of internal trust relationships. Due to…
Abstract
Purpose
Experts may adjust their assessments through communication and mutual influence, and this dynamic evolution relies on the spread of internal trust relationships. Due to differences in educational backgrounds and knowledge experiences, trust relationships among experts are often incomplete. To address such issues and reduce decision biases, this paper proposes a probabilistic linguistic multi-attribute group decision consensus model based on an incomplete social trust network (InSTN).
Design/methodology/approach
In this paper, we first define the new trust propagation operators based on the operations of Probability Language Term Set (PLTS) with algebraic t-conorm and t-norm, which are combined with trust aggregation operators to estimate InSTN. The adjustment coefficients are then determined through trust relations to quantify their impact on expert evaluation. Finally, the particle swarm algorithm (PSO) is used to optimize the expert evaluation to meet the consensus threshold.
Findings
This study demonstrates the feasibility of the method through the selection of treatment plans for complex cases. The proposed consensus model exhibits greater robustness and effectiveness compared to traditional methods, mainly due to the effective regulation of trust relations in the decision-making process, which reduces decision bias and inconsistencies.
Originality/value
This paper introduces a novel probabilistic linguistic multi-attribute swarm decision consensus model based on an InSTN. It proposes a redefined trust propagation and aggregation approach to estimate the InSTN. Moreover, the computational efficiency and decision consensus accuracy of the proposed model are enhanced by using PSO optimization.
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Sadrudin A. Ahmed, Alain d’Astous and Christian Champagne
This article presents the results of a survey of 202 male Taiwanese consumers. In this study, consumer judgements of two technological products varying in their level of…
Abstract
This article presents the results of a survey of 202 male Taiwanese consumers. In this study, consumer judgements of two technological products varying in their level of complexity made in highly, moderately, and newly industrialised countries were obtained in a multi‐attribute context. The results show that the country‐of‐origin image of moderately and newly industrialised countries was less negative for technologically simpler products (i.e. a television) than they were for technologically complex products (i.e. a computer). It appears that the negative image of moderately and newly industrialised countries can be attenuated by making Taiwanese consumers more familiar with products made in these countries and/or by providing them with other product‐related information such as brand name and warranty. Newly industrialised countries were perceived more negatively as countries of design than as countries of assembly, especially in the context of making technologically complex products. The image of foreign countries as producers of consumer goods was positively correlated with education. The more familiar consumers were with the products of a country, the more favourable was their evaluation of that country. Consumer involvement with purchasing a technologically complex product such as a computer was positively associated with the appreciation of products made in moderately industrialised countries. Managerial and research implications are derived from these results.