Search results

The purpose of this paper is to fabricate a new Cu-Sn-Ni-Cu interconnection microstructure for electromigration studies in 3D integration.

The Cu-Sn-Ni-Cu interconnection microstructure is fabricated by a three-mask photolithography process with different electroplating processes. This microstructure consists of pads and conductive lines as the bottom layer, Cu-Sn-Ni-Cu pillars with the diameter of 10-40 μm as the middle layer and Cu conductive lines as the top layer. A lift-off process is adopted for the bottom layer. The Cu-Sn-Ni-Cu pillars are fabricated by photolithography with sequential electroplating processes. To fabricate the top layer, a sputtered Cu layer is introduced to prevent the middle-layer photoresist from being developed. With the final Cu electroplating processes, the Cu-Sn-Ni-Cu interconnection microstructure is successfully achieved.

The surface morphology of Cu-Sn pillars consists of densely packed clusters which are formed by an ordered arrangement of tetragonal Sn grains. The diffusion of Cu atoms into the Sn phases is observed at the Cu/Sn interface. Furthermore, the obtained Cu-Sn-Ni-Cu pillars have a flat surface with an average roughness of 13.9 nm. In addition, the introduction of Ni layer between the Sn and the top Cu layers in the Cu-Sn-Ni-Cu pillars can mitigate the diffusion of Cu atoms into Sn phases. The process is verified by checking the electrical performance using four-point probe measurements.

The method described in this paper which combined a three-mask photolithography process with sequential Cu, Sn, Ni and Cu electroplating processes provides a new way to fabricate the interconnection microstructure for future electromigration studies.

The purpose of this paper is to study the microstructure and mechanical behaviour of smaller microbumps for high density solder interconnects.

The microstructure was analyzed by scanning electron microscopy and electron backscatter diffraction tests to determine the Sn grain number of the resultant microbumps. The nanomechanical properties of Sn microbumps were investigated by the nanoindentation and shearing tests to understand the failure mechanism and assess the reliability of ultra-high density solder interconnects with numbered grains.

Only one Sn grain is observed in the interconnect matrix when the microbumps are miniaturized to 40 μm or less. Because of the body-centred tetragonal lattice of ß-Sn unit cell, the mechanical properties of the one-grain Sn microbumps are remarkably anisotropic, which are proved by the difference of the elastic modulus and the stiffness in the different orientations. The shearing tests show that the one-grain Sn microbump has a typical brittle sliding fracture of monocrystal at different shearing speeds.

The paper provides a comparable study for the performance of the bigger solder joints and also makes preliminary research on the microstructure and mechanical behaviour of Sn microbumps with the diameter of 40 μm.

The findings in this paper provide methods of microstructure study by combination of EBSD test and metallographic analysis, mechanical study by combination of nanoindentation test and shearing test, which can provide good guidelines for other smaller microbumps. The strain rate sensitivity exponent of the one-grain Sn microbumps is consistent with the Pb-free bulk solder. This implies that the one-grain Sn microbump has a comparable flow stress to Sn37Pb solder, which is beneficial for Pb-free replacement in higher density microelectronic packaging.

This paper aims to investigate the microstructural evolution rules of the intermetallic compound (IMC) layers in high‐density solder interconnects with reduced stand‐off heights (SOH).

Cu/Sn/Cu solder joints with 100, 50, 20 and 10 μm SOH were prepared by the same reflow process and isothermally aged at 150°C. The IMC microstructural evolution was observed using scanning electron microscopy.

The whole IMC layer (Cu₃Sn + Cu₆Sn₅) grew faster in the solder joints with lower SOH because of the thinner IMC layer before aging. Also, the IMC proportion increased more rapidly in solder joints with the lower SOH. In all solder joints with different SOH, the growth rates of the Cu₃Sn (ϵ) layers were similar, and slowed down with increasing aging time. The Cu₆Sn₅ (η) was consumed by the Cu₃Sn (ϵ) growth at the beginning of the aging stage; while it turned to thickening after a period of aging. Finally, the Cu₆Sn₅ thickness was similar in all the solder joints. It is inferred that the thickness ratio of Cu₃Sn to Cu₆Sn₅ would maintain a dynamic balance in the subsequent aging. Based on the diffusion flux ratio of Cu to Sn at the ϵ/η interface, a model has been established to explain the microstructural evolution of IMC layers in high‐density solder interconnects with reduced SOH. In the model, interfacial reactions are mainly supposed to occur at the ϵ/η interface.

The findings provide electronic packaging reliability engineers with an insight into IMC microstructural evolution in high‐density solder interconnects with reduced SOH.

The purpose of this paper is to study the thermal warpage of a plastic ball grid array (PBGA) mounted on a printed circuit board (PCB) during the reflow process.

A thermal-mechanical coupling method that used finite-element method software (ANSYS 13.1) was performed. Meanwhile, a shadow moiré apparatus (TherMoiré PS200) combined with a heating platform was used for the experimental measurement of the warpage of PBGA according to the JEDEC Standard.

The authors found that the temperature profiles taken from the simulated results and experimental measurement are consistent with each other, only with a little and acceptable difference in the maximum temperatures. Furthermore, the maximum warpage measurements during the reflow process are 0.157 mm and 0.149 mm for simulation and experimental measurements, respectively, with a small 5.37 per cent difference. The experimental measurement and simulated results are well correlated. Based on the validated finite element model, two factors, namely, the thickness and dimension of PCB, are explored about their effect on the thermal warpage of PBGA mounted on PCB during the reflow process.

The paper provides a thorough parametrical study of the thermal warpage of PBGA mounted on PCB during the reflow process.

The findings in this paper illustrate methods of warpage study by combination of thermal-mechanical finite element simulation and experimental measurement, which can provide good guidelines of the PCB design in the perspective of thermal warpage during the reflow process.

The current study investigated the relationship between nostalgia, conspicuous consumption, and impulse buying and compared gender differences in the effects of nostalgia on conspicuous consumption and impulse buying.

A total of 307 college students in western Singapore were recruited. Confirmatory factor analysis and structural equation modeling were conducted to assess the psychometric properties of the scales and estimate model path coefficients. A multi-group analysis was conducted to test if the path coefficients in the research model varied across genders.

This study found that nostalgia had a positive influence on consumers’ conspicuous consumption, which in turn had a positive impact on their impulse buying of sport products. The results of the multi-group analysis also revealed significant differences across gender groups in that the impacts of nostalgia on conspicuous consumption and impulse buying were stronger for male consumers.

This study forges new ground by investigating the intricate dynamics among nostalgia, conspicuous consumption, and impulse buying in the context of sport. By delving into the relationships between them and exploring gender disparities in their effects, this study enhances our understanding of the pivotal role nostalgia plays in shaping consumer behavior in sport. In addition, the identification of gender-specific patterns underscores the significance of tailored marketing approaches for effectively engaging both male and female consumers. Overall, this study presents fresh perspectives that can inform the development of targeted marketing strategies for sport marketers and retailers aiming to optimize their offerings and promotional endeavors.

Thie purpose of this paper is to present the critical success factors (CSFs) for engaging in the building maintenance business in Hong Kong where maintenance is a major market sector.

In this study, CSFs are identified for the business of building maintenance based on data collected from a questionnaire survey and interviews.

A total of 12 CSFs are identified, such as client's satisfaction, certification of company, reliability of service, quality of service, and company reputation, and most are related to two principal factors, namely maintenance service and organization, and project management.

This paper provides a review of building maintenance in Hong Kong and identifies a list of success factors for the business of building maintenance. The identified CSFs and principal factors provide useful reference for maintenance contractors to have a clear understanding of the expectations of the building maintenance market in Hong Kong.

Design-Build (D-B) is a project delivery method in which the owner procures both design and construction services in the same contract from a single legal entity. There is limited research on how communication among parties influences the success of D-B projects. The purpose of this paper is to examine D-B communication issues and provides effective practices on communication to improve D-B procurement processes in the USA.

The research methodology for this study includes a comprehensive review of literature, survey questionnaire, and structured interviews. A questionnaire was developed to collect data from professionals with an average of 23 years of experience related to D-B procurement. Eight structured interviews were conducted to verify and validate the survey questionnaire results.

The results showed that the communication issues vary along with each phase of the D-B process. The primary communication practices influencing the success of D-B projects are: establishing clear points of contact; providing clear and understandable information among stakeholders during the D-B process; and the timely sharing of information to all stakeholders.

The chief limitation of this research is that the primary data were mostly opinions from experts although several empirical data were collected for cross-validation. This research did not consider the relationship of relevant contract clauses and communication issues.

The findings from this paper will help professionals better understand the D-B procurement process.

This is one of the first attempts to discuss D-B communication issues in each different phase of a D-B project.

Traditional procurement approaches are no longer sufficient amidst dire environmental challenges caused by the construction sector. Yet, it is unclear from existing studies what factors could encourage alternatives such as circular procurement (CP). Thus, this study aims to investigate the determinants of CP adoption in the global construction industry.

The study employs a mixed-method approach involving focus group interviews with circular experts and engaging 194 international construction professionals using a questionnaire survey. Multiple statistical techniques, including exploratory factor analysis and fuzzy synthetic modelling, were employed to analyze the data.

The study identified fourteen key benefits that drive the adoption of CP practices in construction, with “Waste management throughout the construction lifecycle,” “Integration of supply chains” and “Opportunities from new business models” as the three most significant. However, a deeper analysis of the interconnections between these drivers revealed four clusters of principal benefit drivers (PBDs). The four principal groups were “lifecycle cost optimization,” “climate impact mitigation,” “circular capability and waste reduction” and “supply chain collaboration.” Through fuzzy synthetic modeling, it was predicted that three out of four PBDs exerted high levels of influence and should be prioritized for developed economies, while all four PBDs had significant levels of influence in developing regions.

The findings provide a useful reference point for policymakers, practitioners and researchers in formulating strategies to accelerate the adoption and implementation of CP practices in different construction industries.

The study provides a novel perspective on CP adoption through understanding and promotion of its benefits. This offers a valuable framework for decision-making in two regional contexts.

This study aims to identify and examine the critical resultant impacts of the coronavirus (COVID-19) pandemic on quality assurance (QA) of cross-border construction logistics and supply chain (CB-CLSC).

This is achieved via embedded mixed-method design pragmatically involving desk literature review, survey and interviews from related experts within the Hong Kong Special Administrative Region (SAR)–Mainland China links. The design is further integrated with descriptive analysis, criticality test, rank agreement analysis, spearman correlation test and sentiment analysis.

The study revealed 10 critical resultant impacts of the COVID-19 pandemic on the QA of CB-CLSC, with the top three including “increased use of digital technologies (M10)”, “worker absence, labour shortage and decrease in work rate (M3)” and “changes to how construction sites operate (M9)”. Three underlying dimensions were discovered among all the critical resultant impacts: “cost-time-worker (CTW)-related impacts”, “work contract and operation (WCO)-related impacts” and “work process (WP)-related impacts”. The critical resultant impacts are reflected in the time, cost, raw materials and work processes, and this could manifest as negative as well as an opportunity to position the QA system to be adequate during the pandemic and post-pandemic era.

The study contributes to the knowledge body as it identifies and examines the critical resultant impacts of the COVID-19 pandemic on the QA of CB-CLSC. This is original research with invaluable primary data collected in the form of surveys and interviews from construction quality experts within the Hong Kong (SAR)–Mainland China links, known as the world’s factory.

Defining and measuring competitiveness has been a major focus in the business and competition literature over the past decades. The paper aims to use data-driven principal component analysis (PCA) to measure firm competitiveness.

A “3Ps” (performance, potential, and process) firm competitiveness indicator system is structured for indicator selection. Data-driven PCA is proposed to measure competitiveness by reducing the dimensionality of indicators and assigning weights according to the endogenous structure of a dataset. To illustrate and validate the method, a case study applying to Chinese international construction companies (CICCs) was conducted.

In the case study, 4 principal components were derived from 11 indicators through PCA. The principal components were labeled as “performance” and “capability” under the two respective super-components of “profitability” and “solvency” of a company. Weights of 11 indicators were then generated and competitiveness of CICCs was finally calculated by composite indexes.

This study offers a systematic indicator framework for firm competitiveness. The study also provides an alternative approach to better solve the problem of firm competitiveness measurement that has long plagued researchers.

The data-driven PCA approach alleviates the difficulties of dimensionality and subjectivity in measuring firm competitiveness and offers an alternative choice for companies and researchers to evaluate business success in future studies.