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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Peripheral end face attachment of exposed copper layers of a first printed circuit board to the surface of a second printed circuit board by surface mount assembly

A printed circuit board (PCB) structure and mounting assembly for joining two PCBs. A first PCB has a top and bottom surface faces and a peripheral end face separating the top and bottom surface. The first PCB has one or more conductive wire ends exposed at a surface of the peripheral end face; the exposed conductive wire ends forming multiple separate electrical contacts across the thickness and length of the PEF surface. A second PCB has a top surface face and one or more conductive pads exposed at the top surface at locations corresponding to locations of the multiple electrical contacts. A surface mount solder material is disposed on one or more exposed conductive pads for electrically connecting with corresponding the multiple electrical contacts. The disposed solder material stably joins the PEF surface of the first PCB to the top surface of the second PCB in a relative perpendicular orientation.

Takken, Todd E.↗
DOE OSTI2021

Peripheral end face attachment of exposed copper layers of a first printed circuit board to the surface of a second printed circuit board by surface mount assembly

A printed circuit board (PCB) structure and mounting assembly for joining two PCBs. A first PCB has a top and bottom surface faces and a peripheral end face separating the top and bottom surface. The first PCB has one or more conductive wire ends exposed at a surface of the peripheral end face; the exposed conductive wire ends forming multiple separate electrical contacts across the thickness and length of the PEF surface. A second PCB has a top surface face and one or more conductive pads exposed at the top surface at locations corresponding to locations of the multiple electrical contacts. A surface mount solder material is disposed on one or more exposed conductive pads for electrically connecting with corresponding the multiple electrical contacts. The disposed solder material stably joins the PEF surface of the first PCB to the top surface of the second PCB in a relative perpendicular orientation.

Takken, Todd E.↗
DOE OSTI2018

Leaching Studies for Copper and Solder Alloy Recovery from Shredded Particles of Waste Printed Circuit Boards

Printed circuit boards (PCBs) comprise various metals such as Cu, Sn, and Pb, as well as platinum group metals. The recovery of metals from PCBs is important not only due to the waste treatment but also for recycling of valuable metals. In the present work, the leaching process of Cu, Sn, and Pb from PCBs was studied using fluoroboric acid and hydrogen peroxide as the leaching agent and oxidant, respectively. Pertinent factors including concentration of acid, temperature, liquid-solid ratio, and concentration of oxidizing agent were evaluated. The results showed 99 pct of copper and 90 pct solder alloy were dissolved at a temperature of 298 K (25 °C) for 180 minutes using 0.6 M HBF{sub 4} for the particle size range of 0.15 to 0.4 mm. Moreover, solid/liquid ratio had insignificant effect on the recovery of metals. Kinetics analysis revealed that the chemical control regime governs the process with activation energy 41.25 and 38.9 kJ/mol for copper and lead leaching reactions, respectively.

36 MATERIALS SCIENCE↗
NASA NTRS1970

A new low-expansion nonflammable printed circuit board

Printed circuit board has a thermal coefficient of expansion similar to that of the electronic component leads. High-expansion composite materials are sandwiched between the outer layers of copper and woven fiber glass.

Kennedy, B. W.↗
NASA NTRS1982

Flexible composite film for printed circuit board

A flexible printed circuit for a printed circuit board in which layers of reaction product composed of a combination of phenoxy resin - polyisocyanate - brominated epoxy resin, and in which the equivalent ratio of those functional groups is hydroxyl group: isocyanate group: epoxy group - 1 : 0.2 to 2 : 0.5 to 3 are laminated on at least one side of saturated polyester film is discussed.

Yabe, K.↗
NASA NTRS1975

Packaging printed circuit boards: A production application of interactive graphics

The structure and use of an Interactive Graphics Packaging Program (IGPP), conceived to apply computer graphics to the design of packaging electronic circuits onto printed circuit boards (PCB), were described. The intent was to combine the data storage and manipulative power of the computer with the imaginative, intuitive power of a human designer. The hardware includes a CDC 6400 computer and two CDC 777 terminals with CRT screens, light pens, and keyboards. The program is written in FORTRAN 4 extended with the exception of a few functions coded in COMPASS (assembly language). The IGPP performs four major functions for the designer: (1) data input and display, (2) component placement (automatic or manual), (3) conductor path routing (automatic or manual), and (4) data output. The most complex PCB packaged to date measured 16.5 cm by 19 cm and contained 380 components, two layers of ground planes and four layers of conductors mixed with ground planes.

Perrill, W. A.↗
DOE OSTI2019

Solder assembly of pins to the peripheral end face of a printed circuit board

A printed circuit board (PCB) and PCB assembly. The PCB is formed of a laminate substrate of at least two layers of a non-conductive material forming at least one peripheral end face (PEF) surface separating top and bottom PCB surfaces. Embedded conductive wiring at one or more multiple layers carry energy to or from PCB surface mounted devices. The conductive wiring provides multiple conductive wire ends exposed at multiple locations along the PEF. A conductive contact structure is formed at the PEF surface to connect with one or more of the exposed conductive wire ends. One or more conductive pins are attached to the conductive contact at the PEF and are configured to mount the PCB on, and in a vertical and perpendicular orientation or a coplanar orientation relative to, a surface of a second PCB surface. The conductive pins provide one or more of: an electrical, thermal and/or mechanical contact.

Takken, Todd E.↗
DOE OSTI2018

Design and dynamic modeling of printed circuit heat exchangers for supercritical carbon dioxide Brayton power cycles

Due to the unique geometries and hydraulics of printed circuit heat exchangers and rapidly changing properties of supercritical carbon dioxide, the effective design and rating of printed circuit heat exchangers is an essential requirement for their use in supercritical carbon dioxide power cycles. In this study, one-dimensional design and dynamic models have been developed in Aspen Custom Modeler for printed circuit heat exchangers utilized in printed circuit heat exchangers Brayton power cycles. The design model is used to determine the optimal geometry parameters by minimizing the metal mass. The dynamic model is used to predict transient behavior and can be easily implemented into system-level models developed in Aspen Plus Dynamics for cycle performance evaluations. In these models, the heat transfer coefficient and friction factor are calculated using data reported by Heatric, a prominent printed circuit heat exchanger manufacturer. Both models are validated by comparing with the data from a small-scale exchanger used in the 100 kWe facility operated by the Naval Nuclear Laboratory, and then applied to design and simulate low- and high-temperature recuperators for a 10 MWe supercritical carbon dioxide indirect recompression closed Brayton cycle, which is of interest to the U.S. Department of Energy. The designs and dynamic responses of the printed circuit heat exchangers are compared with conventional shell-and-tube exchangers and microtube shell-and-tube exchangers for the same applications. Here, the simulation results indicate that the proposed printed circuit heat exchangers have fast dynamic responses due to their small metal masses and high heat transfer coefficients compared with the conventional shell-and-tube exchangers. Even though the metal masses of the designed PCHEs are slightly higher than those of the microtube shell-and-tube exchangers, the printed circuit heat exchangers are still promising candidates for heat recuperation because of their mature manufacturing procedures and abundant laboratory and industrial operating experience.

42 ENGINEERING↗
NASA NTRS2018

Printed Circuit Board Inspection and Quality Control - PCB Failure Causes and Cures

This two day workshop will discuss a range of topics, including root cause analysis, physics-of-failure principles and failure mechanisms in printed circuit boards. Printed circuit boards (PCBs) are the baseline for electronics manufacturing upon which electronic components are mounted and formed into electronic systems. PCBs are used in a variety of electronic circuits from simple one-transistor amplifiers to large super computers. A PCB serves three main functions: 1) it provides the necessary mechanical support for the components in the circuit 2) it provides the necessary electrical interconnections, and 3) it bears some form of legend which identifies the components it carries. The failure modes on the PCBs can be categorized in a hierarchical structure, in which the mechanisms and causes are site or location dependant. Specimen preparation techniques, non-destructive and destructive analysis, and materials characterization will also be discussed. The first day of the workshop will present methodologies for identifying potential failure mechanisms in electronics based on the failure history and, systematic approaches to root cause analysis. The second day will cover failure analysis techniques geared towards various failure mechanisms, along with numerous component and PCB assembly failure analysis case studies that illustrate the techniques and analysis. Failure analysis case studies will be used to illustrate the techniques and analysis principles to arrive at the root cause(s) of field failures on printed circuit boards, active components, and assemblies.

Printed circuit boards↗
NASA NTRS1973

Welded printed circuit (pc) stick

Printed-circuit stick module has reduced comb technique to six steps, cutting process time by approximately 50%. Method incorporates all type of components into one assembly. It reduces design and fabrication time for 14-lead flat pack to less than four hours and for the 22-lead flat pack to four hours. Average weight of each flat pack is also reduced to 2 g.

Kreis, F.↗
NASA NTRS1993

Low impedance printed circuit radiating element

A printed circuit radiating element comprises a geometrically symmetric planar area of a conducting material separated from a ground plane by a dielectric medium. The driving point of the radiating element is at the base of a notch in one side thereof so that the driving impedance is reduced from that obtained when the element is driven at its edge. Symmetrically disposed on opposite sides of an axis of symmetry of the element along which the driving point lies are two notches which restore the electrical symmetry of the radiating element thereby to suppress higher order modes. The suppression of these higher order modes results in a radiation pattern with minimal cross-polarized energy in the principal planes and high port-to-port isolation which could not be achieved with an asymmetrical element. Two driving points may be employed with the radiating element to produce a dual linearly polarized antenna and a reactive combiner or hybrid may be employed to obtain circularly-polarized radiations. The shape of the radiating element may be square, rectangular or circular, for example, in accordance with the desired characteristics. A plurality of radiating elements may be interconnected via appropriate transmission paths to form an antenna array.

Rahm, James K.↗
NASA NTRS2009

Improving Heat Transfer Performance of Printed Circuit Boards

This paper will explore the ability of printed circuit boards laminated with a Carbon Core Laminate to transfer heat vs. standard printed circuit boards that use only thick layers of copper. The paper will compare the differences in heat transfer performance of printed circuit boards with and without CCL.

Schatzel, Donald V.↗
DOE OSTI2020

Measured Energy-Dependent Neutron Attenuation Through the Stacked Printed Circuit Boards

Engineers often stack printed circuit boards (PCBs), populated with semiconductor devices, one behind the other in neutron beams to improve the error statistics in radiation-effects tests. As the neutron beam traverses through the boards, the neutron flux is both attenuated and the energy spectrum changes, which may have a significant impact on the results of such tests. In this work, we have developed a technique to measure the energy-dependent neutron attenuation due to the PCBs and to determine the energy-dependent effective cross section of neutron interactions with a single PCB. With this effective cross section, engineers can calculate the change in the neutron energy spectrum and the total neutron attenuation after any number of identical PCBs in the stack. This information will allow test engineers to partially correct inaccuracies in soft error tests.

42 ENGINEERING↗