Search results

A product's design influences its manufacturing process and the associated costs. Consequently, design engineers need to review their designs from a manufacturing perspective. While ‘Design For Manufacturing’ (DFM) tools often identify the manufacturing problems associated with a design, they would be more effective if these problems could be represented to the designer in terms of a cost value. This research developed a cost estimation tool for the designer in the surface mount printed circuit board (PCB) domain by integrating computer aided design, computer aided process planning (CAPP) and cost estimation techniques using a knowledge based framework. The cost estimation can be done in two design stages. First, an initial approximation of the manufacturing cost can be obtained using information such as the component mix, type of substrate and the size of board. After the detailed design of the PCB has been developed, a more accurate PCB assembly cost can be obtained using computer aided design (CAD) data. Both cost determination strategies would require the generation of a macro‐process plan. The cost advisor considers tangible and intangible factors. This cost advisor and the DFM environment have been developed using C ++ and object oriented programming constructs under the MS Windows operating system.

The purpose of the present study was to review the thermo-mechanical challenges of reflowed lead-free solder joints in surface mount components (SMCs). The topics of the review include challenges in modelling of the reflow soldering process, optimization and the future challenges in the reflow soldering process. Besides, the numerical approach of lead-free solder reliability is also discussed.

Lead-free reflow soldering is one of the most significant processes in the development of surface mount technology, especially toward the miniaturization of the advanced SMCs package. The challenges lead to more complex thermal responses when the PCB assembly passes through the reflow oven. The virtual modelling tools facilitate the modelling and simulation of the lead-free reflow process, which provide more data and clear visualization on the particular process.

With the growing trend of computer power and software capability, the multidisciplinary simulation, such as the temperature and thermal stress of lead-free SMCs, under the influenced of a specific process atmosphere can be provided. A simulation modelling technique for the thermal response and flow field prediction of a reflow process is cost-effective and has greatly helped the engineer to eliminate guesswork. Besides, simulated-based optimization methods of the reflow process have gained popularity because of them being economical and have reduced time-consumption, and these provide more information compared to the experimental hardware. The advantages and disadvantages of the simulation modelling in the reflow soldering process are also briefly discussed.

This literature review provides the engineers and researchers with a profound understanding of the thermo-mechanical challenges of reflowed lead-free solder joints in SMCs and the challenges of simulation modelling in the reflow process.

The unique challenges in solder joint reliability, and direction of future research in reflow process were identified to clarify the solutions to solve lead-free reliability issues in the electronics manufacturing industry.

Farm labor contractors operate as intermediaries between farmworkers and agricultural employers by recruiting and supplying labor to US farms. In a political economy where there are employer sanctions for hiring workers without proper documentation, contractors share risk alongside final employers. Furthermore, contractors may facilitate quick employment matches during time sensitive agricultural tasks such as harvesting. For undocumented workers, using a contractor may decrease uncertainty associated with a foreign labor market and ease language barriers. The purpose of this paper is to examine the current role of labor contractors in delivering immigrant agricultural workers, particularly undocumented workers, to farms.

Determinants of labor contractor use and relationships to final worker outcomes are examined using econometric methods and a large nationally‐representative worker survey that is distinctive in that it distinguishes legal status.

Undocumented farmworkers are shown to be more likely to use contractors than are documented workers, though statistical significance is sensitive to the inclusion of crop and task indicators, and wages and fringe compensation to workers who use contractors are lower, even after controlling for legal status.

The paper contributes to limited recent academic work on the role of labor contractors in US agriculture. Future work may examine ongoing changes to this role in the context of mutable immigration policy and public opinion.

It is argued that the decline in labor contracting increases the need for employer‐level bilingual communication skills and compliance with labor regulations.

Understanding current dynamics of the agricultural labor market should be of value to scholars of rural economies, farm owners and agricultural policymakers.

To design a flexible integrated robotic assembly and rework (remanufacturing) cell for assembly, selective assembly and rework of advanced surface mount components (SMCs) using the generic methodology developed in this paper.

Manual rework procedures are investigated for all advanced SMCs. General and specific component‐related rework considerations are obtained and necessary tooling candidates for automation are determined. This is followed by determination of the specific automated rework procedure and selection of suitable tooling for automated robotic rework and generation and evaluation of design concepts.

The developed methodology, which considers the reflow tool at the centre of the development process, has worked well in designing a flexible integrated robotic assembly and rework cell.

This study identified the rework requirements for advanced SMCs, the essential features for rework reflow tools, criteria for comparing reflow tools, and a generic procedure for design and concept selection.

It provides valuable knowledge for designers of flexible integrated robotic assembly and rework cells for assembly, selective assembly and rework of advanced SMCs.

A neural‐network‐based predictive model is proposed to model the second‐side thermal profile reflow process in surface mount assembly with a view to facilitating the oven set‐up procedure and improving production yield.

This study performs a 3⁸⁻⁴ fractional factorial experimental twice to collect the thermal‐profile data from a second‐side board. The first experiment has components on the second side only, while the second experiment also has additional components on the primary side. A back‐propagation neural network (BPN) is then used to model the relationship between control variables and thermal‐profile measures.

Empirical results illustrate the efficiency and effectiveness of the proposed BPN in solving the second‐side thermal‐profile prediction and control problem.

There is no study dedicated to the investigation of the second‐side thermal‐profile variance with and without the presence of primary‐side components. The study suggests that a variant oven‐setting strategy for the second‐side reflow process is important to ensure reflow‐soldering quality.

This paper studies test of hypotheses for the slope parameter in a linear time trend panel data model with serially correlated error component disturbances. We propose a test statistic that uses a bias corrected estimator of the serial correlation parameter. The proposed test statistic which is based on the corresponding fixed effects feasible generalized least squares (FE-FGLS) estimator of the slope parameter has the standard normal limiting distribution which is valid whether the remainder error is I(0) or I(1). This performs well in Monte Carlo experiments and is recommended.

Purpose – To introduce autoethnography as an innovative research approach within sport and physical culture, and consider its key tenets, strengths and weaknesses. For illustrative purposes, the chapter draws upon two specific autoethnographic research projects on distance running – one collaborative and one solo.

Design/methodology/approach – The design of the two projects is delineated, including methods of data collection and analysis: tape-recorded field and ‘head’ notes, personal and analytic logs, phenomenological, thematic and narrative data analysis. Issues of representation are addressed and the chapter explores salient, but often-overlooked, ethical considerations in undertaking autoethnographic research.

Findings – Key findings of two research projects are presented, cohering around issues of identity construction and identity work, together with lived body and sensory experiences of distance running.

Research limitations/implications – The limitations of using an autoethnographic approach are discussed, including in relation to fulfilling traditional, positivistic judgment criteria such as validity, reliability and generalisability; more appropriate criteria are proposed, particularly in relation to evocative autoethnographies. Novel forms of the genre: collaborative autoethnography and autophenomenography, are suggested as future directions for autoethnographic research in SPC.

Originality/value – The chapter provides a succinct introduction to the use of autoethnography in sport and physical culture, for those unfamiliar with the genre. The author also suggests an innovative variation – autophenomenography.

This chapter combines quantitative studies of the connections between stressors and performance in accounting settings and identifies the mediators and moderators of stressors–performance relationships. Using meta-analyses and path analyses, this research compiles 72 studies to investigate the relationships of stressors with accountant and auditor performance. As hypothesized, bivariate meta-analyses results indicate that work-related stressors negatively affect performance, and burnout and stress are negatively related to performance, whereas motivation is positively related to performance. Moreover, a meta-analytical structural equation modeling indicates that role stressors have significant direct and indirect effects (through burnout and stress) on job performance. Accumulation of multiple samples through meta-analysis bolsters statistical power compared to single-sample studies and thus reveals the sign of residual direct effects of role stressors on job performance in accounting settings.

The field of Human Resource Management (HRM) has long recognized the importance of interpersonal influence for employee and organizational effectiveness. HRM research and practice have focused primarily on individuals’ characteristics and behaviors as a means to understand “who” is influential in organizations, with substantially less attention paid to social networks. To reinvigorate a focus on network structures to explain interpersonal influence, the authors present a comprehensive account of how network structures enable and constrain influence within organizations. The authors begin by describing how power and status, two key determinants of individual influence in organizations, operate through different mechanisms, and delineate a range of network positions that yield power, reflect status, and/or capture realized influence. Then, the authors extend initial structural views of influence beyond the positions of individuals to consider how network structures within and between groups – capturing group social capital and/or shared leadership – enable and constrain groups’ ability to influence group members, other groups, and the broader organizational system. The authors also discuss how HRM may leverage these insights to facilitate interpersonal influence in ways that support individual, group, and organizational effectiveness.