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The purpose of this paper is to investigate oxidation and the Au‐Sn reaction of laser reflowed (LR) micro‐solder joints when different protective atmospheres were applied.

A N2 atmosphere at room temperature, 60°C, 100°C and 130°C, or an air atmosphere at room temperature were utilized in this study. The solder balls were composed of Sn‐2.0Ag‐0.75Cu‐3.0Bi, and 120 μm in diameter. The surface finish of one pad of the joints was 4.0 μm Au/0.1 μm NiFe/0.01 μm Ta, another pad was made of Cu plated with 3.0 μm Au. The laser reflow process time was controlled to within 10 ms. Auger Electron Spectroscopy (AES) was used to identify the oxidation condition of LR solder joints with or without protection from a N2 atmosphere at room temperature. The appearance and cross‐sections of the joints protected by a N2 atmosphere at different temperatures were evaluated using SEM analysis.

Oxidation of LR solder joints from an air atmosphere was extremely severe, and the surfaces of solder were rough as compared with joints protected by a N2 atmosphere. Au‐rich phases and needle‐like AuSn4 intermetallic compounds (IMCs) formed at the interfaces of the solder and the pads. As the temperature of the N2 atmosphere was increased above 100°C, almost all of the Au‐rich phases disappeared. More needle‐like AuSn4 IMCs formed at the interfaces, as compared with that in joints protected by a N2 atmosphere at room temperature and 60°C. In addition, the orientation of the IMCs had clearly changed.

The results may provide a guide for controlling oxidation and the Au‐Sn reaction of micro‐solder joints during the LR process, and improving the properties of joints between solder and pads with Au surface finishes, by regulating the protective atmosphere.

In this paper, the interaction kinetics between eutectic PbSn solder and Au/Ni/Cu metallisation of plastic ball grid array packages during laser reflow bumping were investigated. The effects of processing variables, including laser reflow power and time, on the morphology of the intermetallic compounds formed at the solder/pad interface were studied by scanning electron microscopy and energy dispersive X‐ray spectrometry. Furthermore, dissolution and diffusion of Au and Sn inside the solder bump within the duration of the laser heating was analysed by Auger electron spectroscopy (AES). The results reveal that the morphology of the intermetallic compounds was strongly influenced by the laser input energy. The AES results showed that Au atoms dissolved rapidly into the solder after the solder was melted.

The purpose of this paper is to investigate the effect of typical morphologies of Au-Sn IMCs (intermetallic compounds) at the interfaces of solder and pads on shear properties of laser reflowed micro-solder joints.

Sn-2.0Ag-0.75Cu-3.0Bi (SnAgCuBi) solder balls (120 μm in diameter), pads with 0.1, 0.5, 0.9 or 4.0 μm thickness of Au surface finish, and different laser input energies were utilized to fabricate micro-solder joints with Au-Sn IMCs having different typical morphologies. The joints were performed by a shear test through a DAGE bond test system. Fracture surfaces of the joints were analyzed by scanning electron microscopy and energy-dispersive X-ray spectrometry to identify fracture modes and locations.

Morphologies of Au-Sn IMCs would affect shear properties of the joints remarkably. When needle-like AuSn4 IMCs formed at the interfaces of solder and pads, almost entire surfaces presented the manner of ductile fracture. Moreover, shear forces of this kind of solder joints were higher than those of joints without Au-Sn IMCs or with a nearly continuous/continuous Au-Sn IMCs layer. The reason was that the shear performance of the solder joints with needle-like AuSn4 IMCs was enhanced by an interlocking effect between solder and needle-like AuSn4 IMCs. As a nearly continuous or continuous Au-Sn IMCs layer formed, the fracture surfaces presented more character of brittle than ductile fracture. However, if an Au layer still remained under Au-Sn IMCs, the shear performance of the joints would be enhanced.

The results in this study can be used to optimize microstructures and shear properties of laser reflowed micro-solder joints.

Online retailers have become gradually popular to offer consumers installment payment services in the past few years. This paper aims to study how to determine the duration and rate of installment payment services, as well as the price of products to increase online retailers’ profits.

By modeling the utility functions, the behavior of consumers for strategic choosing the payment method and payment timing is analyzed. Thus, the market segments are obtained through the comparison of the consumer’s utilities. Combined with the given assumptions, the installment payment strategies for online retailers is investigated. This paper focuses on the impact of installment payment services on consumers’ purchasing behavior and online retailers’ profits by modeling and comparative analysis. No installment payment service as a benchmark, it is demonstrated whether online retailers can obtain more profits by offering installment payment services or what are the applicable conditions for installment payments.

If the installment payment service is offered, online retailers can gain more profits and need to adopt appropriate strategies based on different market conditions. During the depression or the peak shopping season, online retailers should take the strategy of free installment rate, and moderately increasing the product price of no installment service. When market demand is stable or during non-peak season, online retailers need to set a higher installment rate and maintain the product price without installment service. Finally, online retailers should determine the maximum duration of installments they can afford based on own risk control cost and allow consumers to freely choose the length of the installment within the duration limit.

First, the authors deeply analyze consumers’ payment and purchase behavior when the online retailer offers the installment payment service. Then, it is theoretically proved why many online retailers have offered installment payment services to consumers from a profit perspective. Finally, this paper proposes the optimal duration of installments, installment rate and product price in different market environments for online retailers, to provide theoretical basis and managerial insights for the development of installment payment service in online shopping.

The purpose of this paper is to provide a feasible scheme for local governments to regulate corporate environmental data fraud and to discuss whether the influence of the construction of online information disclosure platform on the environmental behavior of enterprises is better than the offline spot check.

Under the background of changing environmental fees into taxes in China, this paper conducts evolutionary game analysis between local governments and enterprises in view of the existing problem of environmental data fraud. Furthermore, through the introduction of government information disclosure platform, this paper discusses the impact of the integration of direct government regulation and indirect public concern regulation on the evolution of environmental behavior of both sides. Finally, the evolutionary game is simulated by adopting system dynamics to analyses the implementation effect of different cases on the game process and game equilibrium.

The results showed that the introduction of information disclosure platform mechanism can effectively suppress the fluctuations existing in the game play and stabilize the game. Moreover, it is worth noting that the regulatory effect of local governments investing part of the monitoring cost in the construction of online information platform is proved to be better than that of putting all the monitoring cost into offline investigation. While optimizing the monitoring cost allocation, the local government still needs to attach great importance to organically combine the attention of the public and media with the governmental official platform.

The obtained results confirm that the proposed model can assist local government in refining the effects of their environmental regulatory decisions, especially in the case of corporate data fraud under environmental tax enforcement.

Previous literature only suggested that local governments should reduce the cost of supervision to change the corporate behavior to a better direction, but no further in-depth study. Thus, this study fills the gap by discussing the positive transformation effect of local government cost allocation scheme on corporate environmental behavior.

The goal is to explore the role of international education in a developing country's nation building in a mostly indigenous process.

This study reviews China's history of international education set in the larger context of different nation building tasks in the past two centuries.

The unique case of China with dramatic ups and downs in national fortunes in the past two hundred years serves to show that an open attitude to and an active engagement in international education are contributing factors for national prosperity. The case of China also serves to show that a self-determined agenda is of paramount importance in international education as a tool for nation building.

Few studies so far have paid attention to the specific relationship between the internationalization of higher education and nation building, so the topic of the paper is an important one and a necessary addition to the existing literature. What has been the role of international education in China's national transformation? What contributions has international education made to China's achievement of nation building goals at different stages of this transformation process? What implications can other developing nations draw from China's case with regard to the role of international education in nation building? These are the questions the researchers hope to answer in this study.

This paper aims to explore the direct effects of open innovation (OI) on firms’ innovative performance, and to examine the moderating effects of knowledge attributes, including knowledge distance, knowledge embeddedness and partner opportunism on this relationship.

Survey data of 247 samples from China were used to test the proposed model through hierarchical regression analysis.

The findings indicate that the dimensions of OI are positively related to innovative performance. The results also reveal that knowledge distance positively moderates the relationship between inbound OI and innovative performance, whereas knowledge embeddedness negatively affects that relationship. Knowledge embeddedness negatively affects the relationship between inbound OI and innovative performance, whereas knowledge distance positively moderates that relationship. Thus, a new finding is proposed that knowledge attributes could align effectively with specific OI type to achieve superior innovation outcomes. In addition, the empirical results suggest that partner opportunism plays a negative moderating role on the relationship between outbound OI and innovative performance.

The proposed view that a firm’s innovation outputs will be superior when its knowledge attributes effectively align with OI enriches studies of the OI context and expands the literature of both the resource-based view and the knowledge-based view. Furthermore, this study provides insights into how OI benefits can be influenced by external contexts from the perspective of partners’ opportunistic behaviour.

The purpose of this study is to improve the dispersion of nanoserpentine modified with OA, KH550 and KH550/oleic acid in lubricating oil. The main aims are to analyze the influence of the dispersion and stability of nanoserpentine modified by different modifiers on the friction properties of lubricating oil.

The nanoserpentine particles obtained by ball-milling were modified by silane coupling agent KH550, OA and KH550/OA, respectively. The dispersity and stability of nanoserpentine in base lubricating oil were characterized by the absorbance value method, centrifuge precipitation rate method and static observation method. The MMU-5G screen display friction and wear tester was used to evaluate the tribological properties of C45E4/C45E4 friction pairs in corresponding lubricating oils. The surface morphology of the friction pairs was observed by scanning electron microscopy and energy dispersive spectroscopy.

The results showed that the dispersity and stability of nanoserpentine particles in lubricating oil were best modified by OA, followed by the KH550/OA and finally, the KH550. Nanoserpentine particles modified with oleic acid showed optimum tribological properties as lubricant additives.

This study can improve the dispersion stability of nanoserpentine particles in lubricating oil, increasing the antiwear and antifriction performance of lubricating oil, which has great significance in economic and military aspects.

As an advanced manufacturing method, additive manufacturing (AM) technology provides new possibilities for efficient production and design of parts. However, with the continuous expansion of the application of AM materials, subtractive processing has become one of the necessary steps to improve the accuracy and performance of parts. In this paper, the processing process of AM materials is discussed in depth, and the surface integrity problem caused by it is discussed.

Firstly, we listed and analyzed the characterization parameters of metal surface integrity and its influence on the performance of parts and then introduced the application of integrated processing of metal adding and subtracting materials and the influence of different processing forms on the surface integrity of parts. The surface of the trial-cut material is detected and analyzed, and the surface of the integrated processing of adding and subtracting materials is compared with that of the pure processing of reducing materials, so that the corresponding conclusions are obtained.

In this process, we also found some surface integrity problems, such as knife marks, residual stress and thermal effects. These problems may have a potential negative impact on the performance of the final parts. In processing, we can try to use other integrated processing technologies of adding and subtracting materials, try to combine various integrated processing technologies of adding and subtracting materials, or consider exploring more efficient AM technology to improve processing efficiency. We can also consider adopting production process optimization measures to reduce the processing cost of adding and subtracting materials.

With the gradual improvement of the requirements for the surface quality of parts in the production process and the in-depth implementation of sustainable manufacturing, the demand for integrated processing of metal addition and subtraction materials is likely to continue to grow in the future. By deeply understanding and studying the problems of material reduction and surface integrity of AM materials, we can better meet the challenges in the manufacturing process and improve the quality and performance of parts. This research is very important for promoting the development of manufacturing technology and achieving success in practical application.