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A computational model was established in this study to simulate cavity‐down plastic ball grid array (PBGA) assemblies. Stress analysis was performed to investigate the solder joint reliability of a PBGA‐PCB (printed circuit board) assembly. The packages under investigation had two different body sizes and two kinds of ball population. The diagonal cross‐section of the assembly was modeled by plane‐strain elements and was subjected to a uniform thermal loading. The solder joints were stressed due to the mismatch of the assembly’s coefficient of thermal expansion (CTE). The accumulated effective plastic strain was evaluated as an index for the reliability of solder joints. Effects on solder joint reliability such as package size and ball population were identified. Furthermore, it was found that, unlike conventional PBGA assemblies, the outermost solder ball has the highest plastic strain for all cases in the present study. This peculiar phenomenon was further discussed with the consideration of package deformation.

A computational parametric study on the solder joint reliability of a plastic ball grid array (PBGA) with solder bumped flip chip (FC) is presented. The basic configuration of the PBGA is 27mm package‐size and 1.27mm ball‐pitch. There were three kinds of ball population: four‐row perimeter grid array with/without thermal balls, and full grid array. A total number of 24 cases, involving various chip sizes, chip thicknesses and substrate thicknesses, were studied. The diagonal cross‐section of the PBGA‐printed circuit board (PCB) assembly was modeled by plane‐strain elements and was subjected to uniform thermal loading. Through mismatch of coefficient of thermal expansion (CTE), and lack of structural compliance, the solder joints were stressed to produce inelastic deformation. The accumulated effective plastic strain was evaluated as an index for the reliability of solder joints. The present study revealed the effects of aforementioned design parameters on the solder joint reliability of FC‐PBGA assemblies. Some peculiar phenomena were identified.

The London Interbank Offered Rate (LIBOR) is considered to be the most important interest rate in finance upon which trillions in financial contracts are decided. In 2008, it was revealed that the LIBOR traders were rigging the interest rates. Yet, there is an unresolved question that regulators and banking officials did not address in their quest to seek answers to the fraud: Were the banks under financial strain when they underreported their LIBOR rates? To answer this question, the article posits that the pressure to meet market expectations led the banks to experience financial strain. Data were gathered from 2004 to 2008 on the banks that were involved in the fraud (fraud banks) and matched with a control group of non-fraud banks. The results from a logistic regression model found sufficient statistical evidence to support the claim that fraud will be greater in banks characterized by a higher level of organizational complexity. Variables such as percent of outside directors, board members on the audit committee, and number of employees were all found to be statistically significant. These variables may offer key insights into detecting and preventing frauds in banks.

This major review of organisational stress and its consequences provides a background to assess the policies and principles that need to be developed to counter the problems emerging.

NOTWITHSTANDING the fact that there exists a considerable amount of literature published in various forms on the subject of brittle lacquers and their applications to a multitude of diverse problems a brief resume of some of the general principles involved would seem not to be out of place.

Evidence is mounting to suggest that stress not only influences an individual's well‐being, but can also have an impact on the quality of work they perform. This paper starts with a consideration of some important issues relating to stress in staff who work with people who have learning disabilities, particularly those who work in community group homes. Current research indicates a number of common themes. A model is presented that attempts to summarise some of these. However, it is also clear that there is considerable variability between organisations. This variability must be assessed when considering the needs of individuals and groups of staff. Some groups of staff seem to Report higher levels of stress and can benefit from stress management interventions. For stress management to be effective, assessments that take into account individual and organisational issues are necessary. An example of a successful intervention package is provided. This is based on the assessment of staff teams and implemented within a problem‐solving framework.

The purpose of this paper is to examine how job engagement affects the experience of workplace aggression and the related outcomes. Job engagement is introduced as a context variable for the stressor-strain model to explain differences for targets of workplace aggression.

A survey was conducted with a sample of 492 North American working adults from a large variety of industries and jobs.

Consistent with the hypotheses, fear and anger mediate the relationship between workplace aggression and strain. Job engagement moderated the relationship between workplace aggression and anger, such that aggression related to anger only for those employees who were engaged in their job. These data are consistent with the suggestion that engagement may create vulnerability for employees.

In this study, the authors highlight the need to include contextual factors that may explain differences in impact of workplace aggression and employee wellness.

While practitioners may seek to increase job engagement, there appears to be a greater cost should there be workplace aggression. Thus, the key implication for practitioners is the importance of prevention of workplace aggression.

With this study, the authors illustrate how job engagement may have a “dark side” for individuals. While previous research has shown that job engagement helps protect employee wellness, others show engagement decreases after incidents of workplace aggression. The authors suggest those who are engaged and targeted will experience worse outcomes. Also, the authors examine the role of anger for targets of workplace aggression as it relates to fear and strain in this study.

The solder‐joint reliability of solder‐bumped wafer level chip scale package (WLCSP) on microvia build‐up printed circuit board (PCB) subjected to thermal cycling conditions is investigated in this study. The 62Sn36Pb2Ag solder joints are assumed to be: an elastic material; an elastic‐plastic material; and a creep material which obey the Garofalo‐Arrhenius steady‐state creep constitutive law. The stress and strain in the corner solder joint of the WLCSP assembly are presented and compared for these three material models. Also, the results presented herein will be compared with that from creep analysis of the WLCSP on PCB without microvia build‐up layer.

There has been interest recently in analysing soil, ceramic powders and other materials on the microscopic level so that macroscopic phenomena, such as failure, can be related to microscopic properties. The discrete element method provides a numerical tool for conducting such analyses. Here the basic theory behind the method is reviewed and various formulations derived from a finite element basis. The automatic detection of contact surfaces between bodies is a major problem in analysing the interaction of numerous bodies, common to both finite elements and discrete elements. Various approaches to geometric contact detection and the need for efficient algorithms and data structures utilizing recent developments in the field of computer graphics and solid modelling are discussed. Examples are given of the collapse of a soil embankment, penetration of a projectile into a soil and the large deformation of a space structure.