Non-destructive evaluation of solder joint reliability

A through life non-destructive evaluation technique is presented in which a key solder joint feature, nucleating at the bump to silicon interface and propagating across a laminar crack plane is captured and tracked using acoustic microscopy imaging (AMI). The feasibility of this concept was successfully demonstrated by employing the measurement technique in combination with Finite Element Analysis (FEA) to study the impact of component floor plan layout on the reliability of electronics systems subjected to thermal cycling. A comprehensive review of current and emerging packaging and interconnect technologies has shown increasingly a move from conventional 2D to 3D packaging. These present new challenges for reliability and Non Destructive Evaluation (NDE) due to solder joints being hidden beneath the packaging, and not ordinarily visible or accessible for inspection. Solutions are developed using non-destructive testing (NDT) techniques that have the potential to detect and locate defects in microelectronic devices. This thesis reports on X-ray and Acoustic Micro Imaging (AMI) which have complementary image discriminating features. Gap type defects are hard to find using X-ray alone due to low contrast and spot size resolution, whereas AMI having better axial resolution has allowed cracks and delamination at closely spaced interfaces to be investigated. The application of AMI to the study of through life solder joint behaviour has been achieved for the first time. Finite Element Analysis and AMI performance were compared to measure solder joint reliability for several realistic test cases. AMI images were taken at regular intervals to monitor through- life behaviour. Image processing techniques were used to extract a diameter measurement for a laminar crack plane, within a solder joint damage region occurring at the bump to silicon interface. FEA solder joint reliability simulations for flip-chip and micro-BGA (mBGA) packages placed on FR4 PCB's were compared to the AMI measurement performance, with a reasonable level of correlation observed. Both techniques clearly showed significant reliability degradation of the critical solder joints located furthest from the neutral axis of the package, typically residing at the package corners. The technique also confirmed that circuit board thickness can affect interconnect reliability, as can floor plan. Improved correlation to the real world environment was achieved when simulation models considered the entire floor plan layout and constraints imposed on the circuit board assembly. This thesis established a novel through life solder joint evaluation method crucial to the development of better physics of failure models and the advancement of model based prognostics in electronics systems

Prediction of Electricity Consumption of a HVAC System in a Multi-Complex Building Using Back Propagation and Radial Basis Function Neural Networks

This study examined approaches to predict electricity consumption of a Heating, Ventilation and Air- Conditioning (HVAC) system in a multi-complex building using two neural network models: Back Propagation (BP) and Radial Basis Function (RBF) with input nodes, e.g., temperature, humidity ratio, and wind speed. Predicting HVAC energy consumption of buildings is a crucial part of energy management systems. We used two main neural network models, BP and RBF, to evaluate the prediction performance of electricity consumption of HVAC systems. The BP neural network method exhibited good performance, but it exhibited relatively large fluctuations and slow convergence in the training process. In contrast, RBF exhibited relatively fast learning and reduced computing costs. The HVAC energy consumption rate of working days was higher than that of non-working days. The results indicate that the prediction of HVAC energy consumption using neural networks can effectively control the relationship between the HVAC system and environment conditions.publishedVersio

1996 Laboratory directed research and development annual report

This report summarizes progress from the Laboratory Directed Research and Development (LDRD) program during fiscal year 1996. In addition to a programmatic and financial overview, the report includes progress reports from 259 individual R&D projects in seventeen categories. The general areas of research include: engineered processes and materials; computational and information sciences; microelectronics and photonics; engineering sciences; pulsed power; advanced manufacturing technologies; biomedical engineering; energy and environmental science and technology; advanced information technologies; counterproliferation; advanced transportation; national security technology; electronics technologies; idea exploration and exploitation; production; and science at the interfaces - engineering with atoms

Microscopy Conference 2021 (MC 2021) - Proceedings

Das Dokument enthält die Kurzfassungen der Beiträge aller Teilnehmer an der Mikroskopiekonferenz "MC 2021"

Microfluidics and Nanofluidics Handbook

The Microfluidics and Nanofluidics Handbook: Two-Volume Set comprehensively captures the cross-disciplinary breadth of the fields of micro- and nanofluidics, which encompass the biological sciences, chemistry, physics and engineering applications. To fill the knowledge gap between engineering and the basic sciences, the editors pulled together key individuals, well known in their respective areas, to author chapters that help graduate students, scientists, and practicing engineers understand the overall area of microfluidics and nanofluidics. Topics covered include Finite Volume Method for Numerical Simulation Lattice Boltzmann Method and Its Applications in Microfluidics Microparticle and Nanoparticle Manipulation Methane Solubility Enhancement in Water Confined to Nanoscale Pores Volume Two: Fabrication, Implementation, and Applications focuses on topics related to experimental and numerical methods. It also covers fabrication and applications in a variety of areas, from aerospace to biological systems. Reflecting the inherent nature of microfluidics and nanofluidics, the book includes as much interdisciplinary knowledge as possible. It provides the fundamental science background for newcomers and advanced techniques and concepts for experienced researchers and professionals

EUROSENSORS XVII : book of abstracts

Fundação Calouste Gulbenkien (FCG).Fundação para a Ciência e a Tecnologia (FCT)