Cost-Optimised Reliability Theme
The mission of this theme is to refine test strategies and field-monitoring of telecommunications systems in order to optimise the value-related balance between test effort and field reliability, given the design/architecture of the systems, the intrinsic reliability of their components, and the operational and environmental conditions during usage.
Our objective is to create tools and test techniques to improve the management of system reliability, and this will be achieved through the development of cause-effect models for failures, test optimisation methodologies, performance monitoring systems, and sensors for acquiring environmental conditions. The theme also features the development of solutions for the thermal management of electronic and photonic devices – not only for the removal of high heat fluxes, but also for temperature regulation.
The theme comprises the following tasks:
4.3 Embedded systems for performance / Reliability Monitoring
4.4 Reliability prediction modelling
2.5 Smart Sensors for Environmental Monitoring
Task 4.1: Reliability Physics
The theme of this task is the Design For Reliability (DfR) process for product hardware. The objective of the research is to develop analytical, simulation and experimental approaches to the modelling and monitoring of physical failure mechanisms in telecommunications hardware. Four projects comprise the task:
• Corrosion: the objective of this project is to determine an accelerated test regime suitable for screening out marginal electronic parts susceptible to corrosion-related failures – mechanisms which are known to occur in telecommunications equipment deployed in developing markets. The project will also consider the corrosion performance of new interconnection materials compliant with the European Union's Restriction of Hazardous Substances (RoHS) directive.
• RoHS Reliability: the objective of this project is to examine the reliability of different Sn-Ag-Cu solder alloys with varying Ag content; SAC105, 205, 305 and 405. Accelerated temperature cycling (ATC) and drop testing will be performed. In addition, the effects of nitrogen reflow, cooling rate and isothermal preconditioning will also be investigated.
• Degradation Analysis: the objective of this project is to investigate the exploitation of pre-failure data from critical reliability indicators in order to evaluate measures which describe the anticipated life of a device or system: characteristic life, for example, or Mean-Time-To-Failure. A range of environmental stimuli – temperature and power cycling, for example, and cyclic temperature-humidity exposure – will also be assessed in order to assist in optimising Environmental Stress Test (EST) procedures for specific applications.
• Velocity Amplification: the objective of this project is to develop a machine capable of producing very high mechanical shock and accelerations levels (typically 50,000g+) for applications including MEMS reliability testing and energy harvesting.
Close cooperation with our industrial partners has been established on the task. In addition, the task team has been awarded an Enterprise Ireland Commercialisation Fund Technology Development (CFTD) project on RoHS-Compliant interconnection technologies for telecommunications and power applications.
Task 4.3: Embedded systems for Reliability & Performance Monitoring
The theme of this research is to develop a new real-time approach to continuously monitor performance, in an embedded system based product. This focuses on the monitoring of software execution in the hardware environment, with emphasis on the monitoring of safety properties and timing properties. The research activity is based on a new type of non-invasive at-speed hardware/software embedded monitor architecture, which relates to the formal requirements specifications. It is suggested that a significant number of field faults (and failures) are due to the improper behaviour of ‘correct' software in the hardware execution environment. This project attempts to provide a solution to such problems.
The monitoring approach under investigation is intended to play a part in the development of a more structured DfT approach to testing. The use of standardised interfaces is therefore important. Some specific novel interfaces, to support the monitoring of real-time concurrent activity, are being investigated under the funding of an Enterprise Ireland Proof-of-Concept grant.
Task 4.4: Reliability Prediction
The theme of this task is the development of statistical models for reliability prediction of telecommunication systems and their use in optimising test, production and other processes. The objective of the project is to provide useful analyses and reliability predictions from data on faults and failures in telecommunication products, and to apply these predictions to better decision making in the value chain, from design to test to production. The main outcomes of the project will be as follows: development of Bayesian methods for reliability prediction; development of the belief network approach to modelling the occurrence of failure in telecommunications systems; an understanding of the feasibility of using such models in an industrial setting; their application to the value chain, initially in p rob lems of test optimisation and monitoring of field reliability; statistical models for the behaviour of reconfigurable systems. Cooperation is taking place with the Reconfigurability theme of CTVR, where statistical models for the interference temperature of a network of mobile devices is being modelled, with a view to determining: optimal protocols for mobile devices in such a network and the amount of information required by devices on the network to implement the protocol. The task also features deep collaboration with one of our industrial partners on the optimisation of environmental stress tests (ESTs). It is planned to extend optimisation to other cost-based decisions based on reliability prediction, such as warranty analysis, spare parts strategies and verification.
Task 2.3: Thermal Management
The objective of this task is to develop solutions for the thermal management of electronic and photonic devices – not only for the removal of high heat fluxes, but also for temperature regulation. Current activities aim to create a range of technologies: nanograss surfaced microchannels; micro-jet coolers; variable conductance heat pipes for temperature regulation; and medium temperature heat pipes. A key feature of these technologies is aggressive thermal performance with minimum consumption of energy. Close cooperation with one of our industrial partners has been established on the task
Task 2.5: Smart Sensors for Environmental Monitoring
The objective of this task is to develop a smart sensor ‘plug & play' chip which contains a family of sensors to monitor events which occur in a network. In the context of this theme, the sensor will be used to record environmental data – primarily temperature, relative humidity, vibration & shock, and concentration of corrosive gases – in systems such as optical packages or base stations. Environmental data for a system in field conditions can be used to support the definition of design specifications and test procedures, the estimation of life, failure analysis, and warranty calculation.
The system specifications are based on requirements for high-value telecommunications equipment. Prototypes have been fabricated and are currently being characterised in advance of a second design iteration in mid-2007. An application has been made to Enterprise Ireland 's CFTD Programme to obtain funding to expand and strengthen this work.