An Analytical and Experimental Investigation of Filament Formation in Glass/Epoxy Composites

The drive to increase circuit density with smaller PWB geometries and higher layer counts in multi-layer boards along with the increasing use of electronics in harsh environments for high reliability and safety critical applications (automotive, avionics, medical, military) have made short circuiting of PWBs due to growth of conductive filaments between biased conductors a major concern. In addition, the impending implementation of lead-free soldering processing, which may affect laminate stability and materials choices, can increase the potential for conductive filament formation (CFF) failures. To mitigate these catastrophic failures, it is necessary to understand the roles and synergistic effects of environmental conditions, material properties and manufacturing quality in accelerating or deterring CFF. In this dissertation, four laminate types (including a halogen free) and three conductor spacings are tested at different voltages in accordance with IPC TM-650, allowing a ranking of these laminate types based on resistance to CFF. Demonstrated is the use of an innovative technique, the superconducting quantum interference device (SQUID), to verify and locate the internal short circuits due to CFF. The SQUID which detects magnetic fields generated by the current paths, displays images of the current density enabling identification of the shorted locations. With this technique, a new variant of filament formation in glass/epoxy composites: vertical filament formation (VFF) was identified. The conductive filaments found at the failure sites were observed during cross-sectioning techniques, verifying that the failures were due to CFF. A test standard to identify and quantify hollow glass fibers, potential paths for filament formation in laminated PWBs, was created. It was observed that board types, which show the longest time to failure due to CFF in PTH-PTH configuration, might not offer the best protection for PTH-plane geometry. Based on insulation resistance measurements, it was seen that the IPC-TM-650 test specification of monitoring every 24 hours could allow intermittent failures to go undetected. It was demonstrated that PTH-PTH dielectric breakdown voltage values followed the same trend as the time to failure observed for the PTH-PTH CFF failure data, suggesting that dielectric breakdown voltage can be an indicator of CFF susceptibility, saving considerable time and cost

Voyager spacecraft. Volume III - Voyager program plan Study report, phase IA

Voyager spacecraft implementation pla

Modeling EMI Resulting from a Signal Via Transition Through Power/Ground Layers

Signal transitioning through layers on vias are very common in multi-layer printed circuit board (PCB) design. For a signal via transitioning through the internal power and ground planes, the return current must switch from one reference plane to another reference plane. The discontinuity of the return current at the via excites the power and ground planes, and results in noise on the power bus that can lead to signal integrity, as well as EMI problems. Numerical methods, such as the finite-difference time-domain (FDTD), Moment of Methods (MoM), and partial element equivalent circuit (PEEC) method, were employed herein to study this problem. The modeled results are supported by measurements. In addition, a common EMI mitigation approach of adding a decoupling capacitor was investigated with the FDTD method

Computer Science Research Institute 2004 annual report of activities.

This report summarizes the activities of the Computer Science Research Institute (CSRI) at Sandia National Laboratories during the period January 1, 2004 to December 31, 2004. During this period the CSRI hosted 166 visitors representing 81 universities, companies and laboratories. Of these 65 were summer students or faculty. The CSRI partially sponsored 2 workshops and also organized and was the primary host for 4 workshops. These 4 CSRI sponsored workshops had 140 participants--74 from universities, companies and laboratories, and 66 from Sandia. Finally, the CSRI sponsored 14 long-term collaborative research projects and 5 Sabbaticals

Technology 2002: the Third National Technology Transfer Conference and Exposition, Volume 1

The proceedings from the conference are presented. The topics covered include the following: computer technology, advanced manufacturing, materials science, biotechnology, and electronics

Research and technology

Summaries are presented of the research in the development of the space shuttle. Propulsion, materials, spacecraft and thermal control, payloads, instrumentation, data systems, and mission planning are included

Bibliography of Lewis Research Center Technical Publications announced in 1991

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific engineering work performed and managed by the Lewis Research Center in 1991. All the publications were announced in the 1991 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses