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In general, lighting application, white light emitting diode (LED) usually exposed to an extreme operating temperature of above 90°C. It is well-known that luminous efficacy and spectral characteristic of white LED are dependent on the temperature, causing thermal effects on luminous efficacy and color shift of white LED become a critical application checkpoint to be addressed by white LED manufactures. Thus, the purpose of this paper is to minimize the thermal stability issue affecting white LED luminescence during operation by introducing phosphor sedimentation process.

The LED samples were assembled and sent for centrifugation with 0, 5 and 10 revolutions per second (rps), respectively, during phosphor sedimentation process. Luminescence properties of these LED samples were then characterized at a varying temperature to investigate the effect of phosphor sedimentation on the luminescence stability of LED samples. The LED samples were also cross-sectioned and analyzed to understand the phosphor sedimentation mechanism. Computational fluid dynamics (CFD) was applied to study the temperature distribution of the non-phosphor sediment (NPS) and phosphor sediment (PS) LED during operation to validate the hypotheses based on experimental data.

Experimental results show that the luminous intensity of PS LED samples degrades less significant at high temperature. The experimental results also show that the color coordinate for PS LED samples is more stable and is less blue-shifted than NPS LED samples as the temperature increased. These are because the heat generated by phosphor particles during operation can be dissipated effectively throughout a high thermal conductivity substrate after phosphor sedimentation. Thus, the phosphor temperature of PS LED is lower than NPS LED during operation as validated with the thermal simulation.

The study of this paper is applicable as a reference for industries who intend to resolve the thermal stability of white LED during operation. The luminescence properties changes as a function of the temperature study in this paper can be used to predict the application performances of white LED accurately. Apart from that, the analysis method of temperature distribution using CFD simulations can be extended by other CFD users in the future.

Implementation of phosphor sedimentation to reduce thermal instability issue of white LED has yet to be reported on previous studies. Most literature just studied the thermal instability issue of either assembled LED or raw material, without suggesting any solution to tackle the issue.

The purpose of this paper is to investigate the reliability of wire bonds with three varying ball bond diameters, which are ball bonded with three different sizes of gold wires in light-emitting diode (LED) package under high-temperature environment. In automotive applications, “lifted ball bond” issue is a potential critical point for LED device reliability, as the wire bonds are usually stressed under high operating temperature during their lifetime. Moreover, the reliability of wire bonds in recent LED production has fallen under scrutiny due to the practice of reducing wire diameters to cut down production costs.

Three gold wires with sizes of 2, 1.5 and 1 mm were ball bonded on the LED chip bond pad via thermosonic wire bonding method to produce three different ball bond diameters, that is, 140, 120 and 100 μm, respectively. The reliability of these wire bond samples was then studied by performing isothermal aging at 200°C for the time interval of 30, 100 and 500 hours. To validate hypotheses based on the experimental data, COMSOL Multiphysics simulation was also applied to study the thermal stress distribution of wire bond under an elevated temperature.

Experimental results show that the interfacial adhesion of wire bond degrades significantly after aging at 200°C for 500 hours, and the rate of interfacial degradation was found to be more rapid in the wire bond with smaller ball bond diameter. Experimental results also show that ball bonds randomly elongate along an axis and deforms into elliptical shapes after isothermal aging, and ball bonds with smaller diameters develop more obvious elongations. This observation has not been reported in any previous studies. Simulation results show that higher thermal stress is induced in the wire bond with the decrease of ball bond diameter.

The reliability study of this paper provides measurements and explanation on the effects of wire diameter downsizing in wire bonds for automotive application. This is applicable as a reliability reference for industries who intend to reduce their production costs. Other than that, the analysis method of thermal stresses using COMSOL Multiphysics simulations can be extended by other COMSOL Multiphysics users in the future.

To resolve “lifted ball bond” issue, optimization of the bond pad surface quality and the wire bond parameter has been studied and reported in many studies, but the influence of ball bond diameter on wire bond reliability is rarely focused. Moreover, the observation of ball bonds randomly elongate and deform more into elliptical shape, and ball bond with smaller diameter has the highest elongation after isothermal aging also still has not been reported in any previous studies.

The purpose of this paper is to investigate the efficiencies of argon (Ar), oxygen (O₂) and O₂ followed by Ar (O₂→Ar) plasma treatments in terms of contaminant removal and wire bond interfacial adhesion improvement. The aim of this study is to resolve the “lifted ball bond” issue, which is one of the critical reliability checkpoints for light emitting diodes (LEDs) in automotive applications.

Ar, O₂ and O₂→Ar plasma treatments were applied to LED chip bond pad prior to wire bonding process with different treatment durations. Various surface characterization methods and contact angle measurement were then used to characterize the surface properties of these chip bond pads. To validate the improvements of Ar, O₂ and O₂→Ar plasma treatments to the wire bond interfacial adhesion, the chip bond pads were wire bonded and examined with a ball shear test. Moreover, the contact resistance of the wire bond interfaces was also measured by using four-point probe electrical measurements to complement the interfacial adhesion validation.

Surface characterization results show that O₂→Ar plasma treatment was able to remove the contaminant while maintaining relatively low oxygen impurity content on the bond pad surface after the treatment and was more effective as compared with the O₂ and Ar plasma treatments. However, O₂→Ar plasma treatment also simultaneously reduced high-polarity bonds on the chip bond pad, leading to a lower surface free energy than that with the O₂ plasma treatment. Ball shear test and contact resistance results showed that wire bond interfacial adhesion improvement after the O₂→Ar plasma treatment is lower than that with the O₂ plasma treatment, although it has the highest efficiency in surface contaminant removal.

To resolve “lifted ball bond” issue, optimization of plasma gas composition ratios and parameters for respective Ar and O₂ plasma treatments has been widely reported in many literatures; however, the O₂→Ar plasma treatment is still rarely focused. Moreover, the observation that wire bond interfacial adhesion improvement after O₂→Ar plasma treatment is lower than that with the O₂ plasma treatment although it has the highest efficiency in surface contaminant removal also has not been reported on similar studies elsewhere.

This study aims to understand the factors and problems that relate to Indonesian port competitiveness and the problems that need to be addressed by major actors such as the government and port corporations.

It combines quantitative analysis from 59 survey respondents and qualitative analysis from focus-group discussions and in-depth interviews with port experts, financial bodies, port corporations and government officials on the condition of Indonesian port planning, development and financing.

An Indonesian port competitiveness model was developed, comprising government support, business support and operational performance. The authors found a gap between policy expectation and realization of port facilitation, caused by inefficient government bureaucracy, customs clearance and strategic decision-making. The government's consistency and commitment need work to encourage investor interest. Road connectivity, intermodal transportation, and energy infrastructure should be enhanced to increase operational performance. These problems are caused by a lack of feasibility analysis, consideration of local economic developments, and late adoption of standard technology. The maritime-sector workforce should be trained to be more professional with foreign players, more innovative and more open towards foreign assistance.

Port competitiveness includes government-related variables. The government’s initiatives are welcomed but are not enough. Adequate attention to both micro and macro port is necessary to increase port competitiveness. Future research should develop more comprehensive solutions to increase port competitiveness in Indonesia using problems and factors outlined here.

The study investigated the unique factors and problems that relate to Indonesian port competitiveness. It uses a national scope and rich expert data involved in Indonesia's port industry.

This study aims to examine the relationship between contextual factors and career exploration. Career adaptability mediates the relationship between social support, sense of belonging and career exploration.

This quantitative study involved 291 undergraduates recruited from two universities in China. Data were analyzed using structural equation modeling.

The results indicated that social support and sense of belonging were positively related to career adaptability. Career adaptability was found to be a mediator between relational predictors and career exploration. Contrary to our hypothesis, the direct path from sense of belonging to career exploration was insignificant.

This study highlights the importance of career adaptability in connecting contextual indicators and career exploration in the Chinese context.

This paper aims to analyse how both Lin’s birthplace identity and his Christian identity contributed to his fruitful public career and to ascertain which identity became the most significant.

Archival research is the main method used in this paper. The most important archives drawn from are the Daniel Tse Collection in the Special Collection and Archives of the Hong Kong Baptist University Library. Oral history has also been used in this paper to uncover more material that has not yet been discussed in existing scholarly works.

This paper argues that although Lin’s birthplace identity and social networks helped him to start his business career in Nam Pak Hong and develop into a leader in the local Chaozhou communities, these factors were insufficient to his becoming a respectable member of the Chinese elite in post-war Hong Kong. He became well known not because of his leading position in local Chaozhou communities or any great achievement he had obtained in business but because of his contribution to the development of Christian education. These achievements earned him a reputation as a “Christian educator”. Thus Lin’s Christian identity became more important than his birthplace identity in contributing to his successful public career.

This paper has value in showing how Christian influences interacted with various cultural factors in early Hong Kong. It also offers insights into Lin’s life and motivations as well as the history of the institutions he contributed to/founded. It not only furthers our understanding of the Chinese Christian business elite in early Hong Kong but also provides us with insights when further studying this group of people in other British colonies in Asia.

This paper aims to collect and compile the historical data of Guanfu Salt Farm, officially built by the Song Dynasty (960–1279) within modern Hong Kong territories, to reconstruct its history for the reflection of Hong Kong society of the time.

This paper is largely based on identification and analysis of historical documents, including keyword search on electronic databases and verification with the original sources, with reference to archaeological findings when necessary.

This paper reconstructs the history of Guanfu Salt Farm based on documentary sources with reference to archaeological findings. English translation of Chinese sources is also provided when necessary.

There has been an absence of systematic compilation of historical data of Hong Kong during the Song Dynasty, which are limited in quantity and scattered across different sources. This paper seeks to fill the vacuum of knowledge about pre-colonial Hong Kong, with a more comprehensive reconstruction of the history of Guanfu Salt Farm.

This paper aims to give a brief review on behavioral economics and behavioral finance and discusses some of the previous research on agents' utility functions, applicable risk measures, diversification strategies and portfolio optimization.

The authors also cover related disciplines such as trading rules, contagion and various econometric aspects.

While scholars could first develop theoretical models in behavioral economics and behavioral finance, they subsequently may develop corresponding statistical and econometric models, this finally includes simulation studies to examine whether the estimators or statistics have good power and size. This all helps us to better understand financial and economic decision-making from a descriptive standpoint.

The research paper is original.