The majority of printed circuit boards are copper clad laminates composed of fiberglass cloth impregnated with FR4 epoxy. An important factor affecting the reliability of these assemblies is the integrity of the epoxy/glass fiber interface. The goal of this work is to investigate mechanisms for the loss of adhesive strength between E-glass and FR4 epoxy upon humidity and temperature conditioning. In this paper the authors discuss the distribution of moisture between the interface region and the bulk epoxy examined by neutron reflection, and the relationship of this data to adhesive strength.
The microcomputer revolution in electronics is spreading so rapidly that it is difficult to educate enough people quickly and thoroughly in the new technology. Lawrence Livermore Laboratory's MST-80B was developed as a way to speed learning in in-house training courses, and it is now being widely used outside LLL. The MST-80B trainer is a complete, self-contained, microcomputer system housed in a briefcase. The trainer uses the Intel 8080A 8-Bit Microprocessor (CPU), and it has its own solid-state memory, a built-in keyboard, input and output ports, and a display for visual output. The trainer is furnished with a permanent Monitor Program (in Read-Only Memory) that allows users to enter, debug, modify, and run programs of their own easily. 8 figures, 3 tables.
The transient descriptors of a class of linear third-order systems are presented in graphical form. An example is given with a discussion on the analysis of lag compensation and second-order approximations.
Distributed generation (DG) is becoming an increasingly attractive multi-faceted paradigm in the field of power distribution as economic and environmental factors drive new technologies to be more efficient and less polluting than their earlier counterparts. An attempt is made to examine and compare three types of DG: diesel generators, microturbines, and small wind turbines within the structure of a distribution system. The DG types are compared in both steady-state and transient operation to determine which type is suitable for a particular application. Steady-state operation is examined under heavy loading conditions and each DG type is compared on the basis of the voltage profile improvement and power loss reduction. Transient operation is examined during islanding conditions. The results indicate improvement in the steady-state conditions of a system from DG, but also indicate some significant problems during relatively minor transient events.
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