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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

High temperature solder device for flat cables

A high temperature solder device for flat cables includes a microwelder, an anvil which acts as a heat sink and supports a flexible flat ribbon cable that is to be connected to a multiple pin connector. The microwelder is made from a modified commercially available resistance welding machine such as the Split Tip Electrode microwelder by Weltek, which consists of two separate electrode halves with a removable dielectric spacer in between. The microwelder is not used to weld the items together, but to provide a controlled compressive force on, and energy pulse to, a solder preform placed between a pin of the connector and a conductor of the flexible flat ribbon cable. When the microwelder is operated, an electric pulse will flow down one electrode, through the solder preform and back up the other electrode. This pulse of electrical energy will cause the solder preform to heat up and melt, joining the pin and conductor.

Haehner, Carl L.↗
NASA NTRS2004

The In-Space Soldering Investigation: Research Conducted on the International Space Station in Support of NASA's Exploration Initiative

Soldering is a well established joining and repair process that is of particular importance in the electronics industry. Still. internal solder joint defects such as porosity are prevalent and compromise desired properties such as electrical/thermal conductivity and fatigue strength. Soldering equipment resides aboard the International Space Station (ISS) and will likely accompany Exploration Missions during transit to, as well as on, the moon and Mars. Unfortunately, detrimental porosity appears to be enhanced in lower gravity environments. To this end, the In-Space Soldering Investigation (ISSI) is being conducted in the Microgravity Workbench Area (MWA) aboard the ISS as "Saturday Science" with the goal of promoting our understanding of joining techniques, shape equilibrium, wetting phenomena, and microstructural development in a microgravity environment. The work presented here will focus on direct observation of melting dynamics and shape determination in comparison to ground-based samples, with implications made to processing in other low-gravity environments. Unexpected convection effects, masked on Earth, will also be shown as well as the value of the ISS as a research platform in support of Exploration Missions.

Grugel, R. N.↗
NASA NTRS2006

Experimental Investigation of Solder Joint Defect Formation and Mitigation in Reduced-Gravity Environments

This paper documents a research effort on reduced gravity soldering of plated through hole joints which was conducted jointly by the National Center for Space Exploration Research, NASA Glenn Research Center, and NASA Johnson Space Center. Significant increases in joint porosity and changes in external geometry were observed in joints produced in reduced gravity as compared to normal gravity. Multiple techniques for mitigating the observed increase in porosity were tried, including several combinations of flux and solder application techniques, and demoisturizing the circuit board prior to soldering. Results were consistent with the hypothesis that the source of the porosity is a combination of both trapped moisture in the circuit board itself, as well as vaporized flux that is trapped in the molten solder. Other topics investigated include correlation of visual inspection results with joint porosity, pore size measurements, limited pressure effects (0.08 MPa - 0.1 MPa) on the size and number of pores, and joint cooling rate.

Watson, J. Kevin↗
NASA NTRS2006

The In-Space Soldering Investigation: To Date Analysis of Experiments Conducted on the International Space Station

Soldering is a well established joining and repair process that is of particular importance in the electronics industry. Still, internal solder joint defects such as porosity are prevalent and compromise desired properties such as electrical/thermal conductivity and fatigue strength. Soldering equipment resides aboard the International Space Station (ISS) and will likely accompany Exploration Missions during transit to, as well as on, the moon and Mars. Unfortunately, detrimental porosity appears to be enhanced in lower gravity environments. To this end, the In-Space Soldering Investigation (ISSI) is being conducted in the Microgravity Workbench Area (MWA) aboard the ISS as "Saturday Science" with the goal of promoting our understanding of joining techniques, shape equilibrium, wetting phenomena, and microstructural development in a microgravity environment. The work presented here will focus on direct observation of melting dynamics and shape determination in comparison to ground-based samples, with implications made to processing in other low-gravity environments. Unexpected convection effects, masked on Earth, will also be shown as well as the value of the ISS as a research platform in support of Exploration Missions.

Grugel, Richard N.↗
NASA NTRS2008

Long-Term Effects of Soldering By-Products on Nickel-Coated Copper Wire

An analysis of thirty-year-old, down graded flight cables was conducted to determine the makeup of a green material on the surface of the shielded wire near soldered areas and to ascertain if the green material had corroded the nickel-coated copper wire. Two likely candidates were possible due to the handling and environments to which these cables were exposed. The flux used to solder the cables is known to contain abietic acid, a carboxylic acid found in many pine rosins used for the soldering process. The resulting material copper abietate is green in color and is formed during the application of heat during soldering operations. Copper (II) chloride, which is also green in color is known to contaminate flight parts and is corrosive. Data is presented that shows the material is copper abietate, not copper (II) chloride, and more importantly that the abietate does not aggressively attack nickel-plated copper wire.

Rolin, T. D.↗
NASA NTRS2011

Capacitor Test, Evaluation. and Modeling Within NASA Electronic Parts and Packaging (NEPP) Program. "Why Ceramic Capacitors Fracture During Manual Soldering and How to Avoid Failures"

Presentation discusses: (1) Why Multi-Layer Ceramic Capacitors(MLCCs) crack during manual soldering? Workmanship and parts issues. (2) Do existing qualification requirements assure crack-free soldering? MIL-spec Thermal Shock (TS) testing. MIL-spec Resistance to Soldering Heat (RSH) test. (3) What test can assure reliable soldering? Mechanical characteristics of ceramics. Comparison of three TS techniques: LND, TSD, and IWT. (4) Simulation of TS conditions.

Teverovsky, Alexander↗
NASA NTRS2014

NASA-DoD Lower Process Temperature Lead-Free Solder Project Overview

This project is a follow-on effort to the Joint Council on Aging AircraftJoint Group on Pollution Prevention (JCAAJG-PP) Pb-free Solder Project and NASA-DoD Lead-Free Electronics Project which were the first projects to test the reliability of Pb-free solder joints against the requirements of the aerospace and military community. This effort would continue to build on the results from the JCAAJG-PP Lead-Free Solder Project and NASA-DoD Lead-Free Electronics Project while focusing on a particular failure mechanism currently plaguing Pb-free assemblies, pad cratering.The NASA-DoD Lead-Free Electronics Project confirmed that pad cratering is one of the dominant failure modes that occur in various board level reliability tests, especially under dynamic loading. Pad Cratering is a latent defect that may occur during assembly, rework, and post assembly handling and testing.

electronics↗
NASA NTRS2017

Development of Stable, Low Resistance Solder Joints for a Space-Flight HTS Lead Assemblies

The solder joints in spaceflight high temperature superconductor (HTS) lead assemblies for certain astrophysics missions have strict constraints on size and power dissipation. In addition, the joints must tolerate years of storage at room temperature, many thermal cycles, and several vibration tests between their manufacture and their final operation on orbit. As reported previously, solder joints between REBCO coated conductors and normal metal traces for the Astro-H mission showed low temperature joint resistance that grew approximately as log time over the course of months. Although the assemblies worked without issue in orbit, for the upcoming X-ray Astrophysics Recovery Mission we are attempting to improve our solder process to give lower, more stable, and more consistent joint resistance. We produce numerous sample joints and measure time- and thermal cycle-dependent resistance, and characterize the joints using x-ray and other analysis tools. For a subset of the joints, we use SEMEDS to try to understand the physical and chemical processes that effect joint behavior.

high temperature superconductivity↗
DOE OSTI2025

Superconducting properties of commercially available solders for low-field applications

Solders with superconducting transitions around 4K are useful in low magnetic field environments for AC current leads or in electrical and mechanical bonds. Accurate knowledge of these solders’ superconducting properties is essential for improving high precision experiments. We have measured the electrical resistance of five commercially-available eutectic or near-eutectic solders: 50%Sn-50%Pb, 60%Sn-40%Pb, 60%Sn-40%Pb-0.3%Sb, 52%In-48%Sn, and 96.5%Sn-3.5%Ag, down to 2.3K and in applied magnetic fields from 0 to 0.1 T . We report critical temperatures T c (B), 90%–10% transition widths ΔT c , and zero-temperature critical fields B c,0 . Our best candidate for low-loss AC current wiring in low fields is 50%Sn-50%Pb, which has a zero-field T c,0 = 7.1K (with ΔT c = 0.6 K), and remained high at T c (0.1 T) = 6.9K (ΔT c = 0.6K ). We also report, for the first time, T c and B c of 60%Sn-40%Pb-0.3%Sb and B c,0 of 96.5%Sn-3.5%Ag. Our T c,0 - 3.31K (ΔT c = 0.08K) for 96.5%Sn-3.5%Ag disagrees with a widely adopted value.

Hickman, C. [North Carolina State University, Rale↗
NASA NTRS1968

Thermal resistances of solder-boss/potting compound combinations

Formulas, which can be used as a design tool, are derived to calculate the thermal resistance of solder-boss/potting compound combinations, for different depths of a solder boss, in electronic cordwood modules. Since the solder boss is the heat source, its shape and position will affect the thermal resistance of the surrounding potting compound.

Veilleux, E. D.↗
NASA NTRS1968

Inspection criteria ensure quality control of parallel gap soldering

Investigation of parallel gap soldering of electrical leads resulted in recommendation on material preparation, equipment, process control, and visual inspection criteria to ensure reliable solder joints. The recommendations will minimize problems in heat-dwell time, amount of solder, bridging conductors, and damage of circuitry.

Burka, J. A.↗
NASA NTRS1968

Fixture facilitates soldering operations

Soldering fixture, designed for printed circuit cards, is a basic bench-mounted, self-contained integral unit combining all soldering needs into a compact, readily available work station. All tools, materials, and accessories are available to provide an ideal station to perform critical soldering.

White, C. M.↗
NASA NTRS1975

Testing of printed circuit board solder joints by optical correlation

An optical correlation technique for the nondestructive evaluation of printed circuit board solder joints was evaluated. Reliable indications of induced stress levels in solder joint lead wires are achievable. Definite relations between the inherent strength of a solder joint, with its associated ability to survive stress, are demonstrable.

Espy, P. N.↗
NASA NTRS1980

Low-temperature solder for joining large cryogenic structures

Three joining methods were considered for use in fabricating cooling coils for the National Transonic Facility. After analysis and preliminary testing, soldering was chosen as the cooling coil joining technique over mechanical force fit and brazing techniques. Charpy V-Notch tests, cyclic thermal tests (ambient to 77.8 K) and tensile tests at cryogenic temperatures were performed on solder joints to evaluate their structural integrity. It was determined that low temperature solder can be used to ensure good fin-to-tube contact for cooling-coil applications.

Buckley, J. D.↗
NASA NTRS1982

Heat Lamps Solder Solar Array Quickly

Interconnection tabs in a nine-solar-cell array have been soldered simultaneously with radiant heat. Cells and tabs are held in position for soldering by sandwiching them between compliant silicone-rubber vacuum platen and transparent polyimide sealing membrane. Heat lamps warm cells, producing smooth, flat solder joints of high quality.

Coyle, P. J.↗
NASA NTRS1981

A cause of the non-solderability of ceramic capacitor terminations

The results of an analysis into the cause of the non-solderability of multiple defective part lots from two capacitor manufacturers are described. This analysis consisted of visual, scanning electron microscopic, surface, and metalographic examinations and analyses. The results indicated that non-solderability results from areas of excess porosity in the termination which are caused by segregation of ink constituents during manufacturing. This segregation can be minimized by proper monitoring and control of process variables; where excess porosity does occur, solderability can be improved by proper precleaning of parts.

Cozzolino, M. J.↗
NASA NTRS1983

Preparing Solar Cells for Soldering

Solder paste and contact ribbon dispensed in synchronism. Solder-paste dispenser operates on one cell at a time. Ribbon fed up ramps and into positioned while solder paste is applied. When ramps are moved out of way, ribbon lies down onto cell.

Hagerty, J. J.↗
NASA NTRS1985

Investigation of Low-temperature Solders for Cryogenic Wind Tunnel Models

The advent of high Reynolds number cryogenic wind tunnels has forced alteration of manufacturing and assembly techniques and eliminated usage of many materials associated with conventional wind tunnel models. One of the techniques affected is soldering. Solder alloys commonly used for wind tunnel models are susceptible to low-temperature embrittlement and phase transformation. The low-temperature performance of several solder alloys is being examined during research and development activities being conducted in support of design and fabrication of cryogenic wind tunnel models. Among the properties examined during these tests are shear strength, surface quality, joint stability, and durability when subjected to dynamic loading. Results of these tests and experiences with recent models are summarized.

Firth, G. C.↗