Exploiting virtual prototyping for reliability assessment

Products manufactured by the electronics sector are having a major impact in telecommunications, transportation space applications, biomedical applications, consumer products, intelligent hand held devices, and of course,the computer. Demands from end-users in terms of greater product functionality, adoption of environmentally friendly materials, and further miniaturization continually pose several challenges to electronics companies. In the context of electronic product design and manufacture, virtual prototying software tools are allowing companies to dramatically reduce the number of phsysical prototypes and design iterations required in product development and hence reduce costs and time to market. This paper details of the trends in these technolgies and provides an example of their use for flip-chip assembly technology.

Flexible self-adjustment of task deployment in dynamic environments

This paper presents an investigation into dynamic self-adjustment of task deployment and other aspects of self-management, through the embedding of multiple policies. Non-dedicated loosely-coupled computing environments, such as clusters and grids are increasingly popular platforms for parallel processing. These abundant systems are highly dynamic environments in which many sources of variability affect the run-time efficiency of tasks. The dynamism is exacerbated by the incorporation of mobile devices and wireless communication. This paper proposes an adaptive strategy for the flexible run-time deployment of tasks; to continuously maintain efficiency despite the environmental variability. The strategy centres on policy-based scheduling which is informed by contextual and environmental inputs such as variance in the round-trip communication time between a client and its workers and the effective processing performance of each worker. A self-management framework has been implemented for evaluation purposes. The framework integrates several policy-controlled, adaptive services with the application code, enabling the run-time behaviour to be adapted to contextual and environmental conditions. Using this framework, an exemplar self-managing parallel application is implemented and used to investigate the extent of the benefits of the strategy

Predicting the behaviour of micro-electronic displays using computational mechanics

Micro-electronic displays are indispensible devices used in high performance applications such as aerospace, medical, marine and industrial sectors.These devices provide an interface to real time mission critical devices and therefore require good optical visual performance and high reliability, all this within varied and challenging environments.

Thermo-mechanical analysis of the packaging process for micro-electronic displays

Micro-electronic displays are sensitive devices and its performance is easily affected by external environmental factors. To enable the display to perform in extreme conditions, the device must be structurally strengthened, the effects of this packaging process was investigated. A thermo-mechanical finite element analysis was used to discover potential problems in the packaging process and to improve the overall design of the device. The main concern from the analysis predicted that displacement of the borosilicate glass and the Y stress of the adhesive are important. Using this information a design which reduced the variation of displacement and kept the stress to a minimum was suggested

Emergent self-organisation of wireless sensor networks

This paper describes a protocol for dynamically configuring wireless sensor nodes into logical clusters. The concept is to be able to inject an overlay configuration into an ad-hoc network of sensor nodes or similar devices, and have the network configure itself organically. The devices are arbitrarily deployed and have initially have no information whatsoever concerning physical location, topology, density or neighbourhood. The Emergent Cluster Overlay (ECO) protocol is totally self-configuring and has several novel features, including nodes self-determining their mobility based on patterns of neighbour discovery, and that the target cluster size is specified externally (by the sensor network application) and is not directly coupled to radio communication range or node packing density. Cluster head nodes are automatically assigned as part of the cluster configuration process, at no additional cost. ECO is ideally suited to applications of wireless sensor networks in which localized groups of sensors act cooperatively to provide a service. This includes situations where service dilution is used (dynamically identifying redundant nodes to conserve their resources).

Computer modelling analysis of the globtop's effects on aluminium wirebond reliability

In power electronics modules, heavy aluminium wires, i.e. wire diameters greater than 100 microns, are bonded to the active semiconductor devices and conductor metallization to form electric circuits of the power electronic module. Due to the high currents that may flow through these wires, a single connection usually contains several wires and thus, a large number of wires are used in a power electronics module. Under normal operation or test condition, a significant amount of stresses and strains induced in the wire and bonding interfaces, resulting in failure over time. In this paper, computer modelling techniques are used to analyse the effect of globtop design on the reliability of aluminium wirebonds under cyclic thermal-mechanical loading conditions. The results will show the sensitivity of the reliability of the wirebonds to the changes in the geometry and the material properties of the wirebond globtop.

On variable frequency microwave processing of heterogeneous chip-on-board assemblies

Variable Frequency Microwave (VFM) processing of heterogeneous chip-on-board assemblies is assessed using a multiphysics modelling approach. The Frequency Agile Microwave Oven Bonding System (FAMOBS) is capable of rapidly processing individual packages on a Chip-On-Board (COB) assembly. This enables each package to be processed in an optimal manner, with temperature ramp rate, maximum temperature and process duration tailored to the specific package, a significant benefit in assemblies containing disparate package types. Such heterogeneous assemblies may contain components such as large power modules alongside smaller modules containing low thermal budget materials with highly disparate processing requirements. The analysis of two disparate packages has been assessed numerically to determine the applicability of the dual section microwave system to curing heterogeneous devices and to determine the influence of differing processing requirements of optimal process parameters.