Search results

Flip chip on board (FCOB) solder joint reliability under thermal shock stress was investigated. With underfill materials, the solder joint lifetime was increased from 37 to 1,300/2,480 cycles depending on the particular underfill material used. Through the use of CSAM, SEM, dye penetration tests and cross sectioning, the reliability of a FCOB assembly under thermal shock stress was evaluated. Both dye penetration and SEM fracture analysis can be used to measure quantitatively the extent of crack propagation for assemblies without underfill. A new failure mechanism, PCB cracking was also observed and discussed.

In this study, we propose and develop an opensource groupware system called NetIsle. NetIsle is a general purpose groupware system for uniform open groups that integrate a number of tools for online collaboration to ensure fast information exchange and sharing, increase the productivity of working groups, and reduce maintenance and administration costs. The main technologies used for the construction of the system are peer‐to‐peer (P2P) and push, which are best fitted to those principles and beliefs we build our system upon.

Flip chip solder joint reliability under thermal shock stress was investigated both experimentally and by 2D finite element simulation. The results indicate that solder fatigue is the dominant failure mode and that delamination has obvious adverse effects on the solder joint lifetime. Different material/process combinations (underfill, flux, reflow atmospheres) were designed in order to understand the role of material/process factors on the solder joint lifetime and the results are discussed.

The lifetime of flip chip solder joints can be greatly increased by applying underfill encapsulation. This paper presents a case study where the thermal cycle lifetime was increased by more than 20 times, that is from ∼100 cycles to more than 2,000 cycles for a chip size of 5.6mm × 6.3mm. By combining electrical, acoustic and metallographic investigation, the degradation of the solder joints was monitored, some important factors relevant to solder joint reliability were analysed and discussed. Delamination was found not to be the dominant failure mode.

Legislative hearings are a relatively new way of encouraging citizen participation in administrative law making within China. The first such hearing in Liaoning Province (Dalian City) was held in April 2005. The purpose of this paper is to examine the detail of the hearing process and attempts to assess its effectiveness as a mechanism for engagement between citizen and the state.

The authors consider both the practicalities of running a public hearing and its influence on the legal regulations under scrutiny. More generally, and within the limits of one case study, we consider whether hearings have the potential to shift the balance of power away from the state and its officials towards a more inclusive form of decision‐making.

Legislative public hearings appear to offer the opportunity for public engagement. The out‐workings of these in practice, if the Dalian case study and secondary evidence from five other Chinese cities is typical, suggests practical limitations, some of which are bound up with the cultural origins of a paternalistic public sector in China and deference to authority.

This paper examines whether citizen participation has been influenced by the wider global reform process of new public management and modernisation, synonymous with developed countries and offers insight into a more inclusive form of decision making for other public services.

To construct a scientific and reasonable indicator system, it is necessary to design a set of standardized indicator primary selection and optimization inspection process. The purpose of this paper is to provide theoretical guidance and reference standards for the indicator system design process, laying a solid foundation for the application of the indicator system, by systematically exploring the expert evaluation method to optimize the index system to enhance its credibility and reliability, to improve its resolution and accuracy and reduce its objectivity and randomness.

The paper is based on system theory and statistics, and it designs the main line of “relevant theoretical analysis – identification of indicators – expert assignment and quality inspection” to achieve the design and optimization of the indicator system. First, the theoretical basis analysis, relevant factor analysis and physical process description are used to clarify the comprehensive evaluation problem and the correlation mechanism. Second, the system structure analysis, hierarchical decomposition and indicator set identification are used to complete the initial establishment of the indicator system. Third, based on expert assignment method, such as Delphi assignments, statistical analysis, t-test and non-parametric test are used to complete the expert assignment quality diagnosis of a single index, the reliability and validity test is used to perform single-index assignment correction and consistency test is used for KENDALL coordination coefficient and F-test multi-indicator expert assignment quality diagnosis.

Compared with the traditional index system construction method, the optimization process used in the study standardizes the process of index establishment, reduces subjectivity and randomness, and enhances objectivity and scientificity.

The innovation point and value of the paper are embodied in three aspects. First, the system design process of the combined indicator system, the multi-dimensional index screening and system optimization are carried out to ensure that the index system is scientific, reasonable and comprehensive. Second, the experts’ background is comprehensively evaluated. The objectivity and reliability of experts’ assignment are analyzed and improved on the basis of traditional methods. Third, aim at the quality of expert assignment, conduct t-test, non-parametric test of single index, and multi-optimal test of coordination and importance of multiple indicators, enhance experts the practicality of assignment and ensures the quality of expert assignment.

Following the hierarchy-of-effects model, this study aims to propose a two-step process framework to investigate social media post efficacy via attraction and likes.

The study analyzes 113,785 social media posts from 126 WeChat official accounts to explore how external (headline features and account type) and internal (content features and media type) features impact social media post attractions and likes, respectively.

The antecedents of post attraction differ from those of post likes. First, headline features (punctuation, length, sentiment and lexical density) and account type significantly influence social media post attraction. Second, content features (depth, tone, domain specificity, lexical density and readability) and media type affect social media post likes.

First, this study considers online user engagement as a two-step process regarding social media posts and explores different influencing factors. Second, the study constructs new variables (account type and domain specificity) in each stage of the two-step process model.

Despite the literature on subordinates' destructive responses to abusive leadership, an emerging body of literature proposes that subordinates may react constructively to abusive supervision under certain conditions. The authors contribute to this line of research by proposing and testing the moderating effects of performance-approach and -avoidance goal orientation on the relationship between abusive supervision and task performance, and by testing work effort as a mechanism underlying this moderating effect.

The study hypotheses were tested in two studies. In Study 1 (field survey, N = 230), the moderation hypotheses were tested. Study 2 (experiment, N = 116) extended Study 1 and examined the mediated moderation model.

The study empirical evidence from the two studies showed that (1) abusive supervision was more positively related to an employee's task performance when that employee's performance-approach goal orientation was high (vs low), (2) abusive supervision was not more positively related to task performance when performance-avoidance goal orientation was high (vs low) and (3) the employee's work effort mediated the moderating effect of performance-approach goal orientation.

This research suggests that organizations and subordinates should be aware of the positive contextual role of performance-approach goal orientation, which may shape subordinates' subsequent work behavior in response to supervisors' hostility, and should invest more time and effort in reinforcing subordinates' performance-approach goal orientation.

This study has identified a new condition and offers new evidence of the potential functional effect of abusive supervision. Specifically, the study finding of the positive moderating role of performance-approach goal orientation adds to the literature examining when abused subordinates respond constructively to abusive supervision. The study analysis of the mediating effect of work effort further reveals the mechanism of this effect.

The purpose of this paper is to maraging 18Ni-300 steel fabricate by powder bed based selective laser melting (SLM) process. Microstructure and mechanical properties of the maraging steel part before and after heat treatment at a slow cooling rate were investigated.

The microstructure of the printed part was observed by optical microscopy and scanning electron microscopy. The phases were determined by X-ray diffraction. The surface roughness of the part was recorded by a profilometer. The tensile properties and microhardness of the parts before and after heat treatment were characterized by an electronic universal tensile testing machine and a Vickers hardness tester, respectively.

Maraging 18Ni-300 steel part comprised of the martensitic phase and a small fraction of austenite phase. After heat treatment, the volume fraction of austenite slightly increased. The surface roughness of the part was about 96 µm. The printed part was dense, but irregular pores were present. The yield strength, ultimate tensile strength (UTS), elongation and Young’s modulus of as-fabricated parts were 554.7 MPa, 1173.1 MPa, 10.9% and 128.9 GPa, respectively. The yield strength, UTS, elongation and Young’s modulus of as-treated parts were 2065 MPa, 2225 MPa, 4.2% and 142.5 GPa, respectively. The microhardness values of surface and cross-section of the as-fabricated part were 407.1 HV and 443.0 HV, respectively. After short-time heat treatment, the microhardness values of the surface and cross-section of the part were 542.7 HV and 567.3 HV, respectively. After long-time heat treatment, the microhardness values of the surface and cross-section of the part were 524.4 HV and 454.8 HV, respectively. The microhardness and tensile strength increased significantly with decreasing elongation due to the changes in phases and microstructure of the parts after heat treatment.

This work studied the effect of heat treatment at 550°C combined with a subsequent slow cooling rate on microstructure and mechanical properties of maraging 18Ni-300 steel obtained by the powder bed based SLM process.

The vulnerability of multinational corporation (MNC) knowledge network is one of the major causes for the failure and even the death of MNCs in the fierce global market competition. Employee turnover and knowledge loss are the triggers for the MNC knowledge network vulnerability and a matter of serious concern in the evolution and development of MNC knowledge network. The purpose of this work is to propose a valid and quantitative measurement method to investigate the influence of employee loss and knowledge loss on the vulnerability of MNC knowledge network.

MNC knowledge network is inherently a heterogeneous network where there are mainly two types of units: employees and their knowledge. Therefore, this paper establishes a weighted super-network model for MNC knowledge network to depict its heterogeneous composition. On the basis of the weighted MNC knowledge super-network, the static and dynamic vulnerability measurement methods are further proposed to investigate and evaluate MNC knowledge network vulnerability.

A real case is given to illustrate the applicability of the proposed weighted MNC knowledge super-network model and the network vulnerability measurement methods. The results show the super-network model proposed in this paper can effectively embody the complex features of MNC knowledge network, and the vulnerability measurement methods can effectively investigate the influence of employee loss and knowledge loss on network vulnerability.

From the perspective of super-network, researchers and practitioners can get a more systematic and deeper understanding of the MNC knowledge network and its human and knowledge resource constitute which are vital for the evolution and development of MNC. Moreover, the MNC knowledge network vulnerability measurement methods can effectively measure and analyze the influence of resource loss on network vulnerability, which can provide a helpful decision support for monitoring and managing of MNC knowledge network vulnerability to reduce its adverse effects.