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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
NASA NTRS2004

Joint Lead-Free Solder Test Program for High Reliability Military and Space Applications

Current and future space and defense systems face potential risks from the continued use of tin-lead solder, including: compliance with current environmental regulations, concerns about potential environmental legislation banning lead-containing products, reduced mission readiness, and component obsolescence with lead surface finishes. For example, the United States Environmental Protection Agency (USEPA) has lowered the Toxic Chemical Release reporting threshold for lead to 100 pounds. Overseas, the Waste Electrical and Electronic Equipment (WEEE) and the Restriction on Hazardous Substances (RoHS) Dicctives in Europe and similar mandates in Japan have instilled concern that a legislative body will prohibit the use of lead in aerospace/military electronics soldering. Any potential banning of lead compounds could reduce the supplier base and adversely affect the readiness of missions led by the National Aeronautics and Space Administration (NASA) and the U.S. Department of Defense (DoD). Before considering lead-free electronics for system upgrades or future designs, however, it is important for the DoD and NASA to know whether lead-free solders can meet their systems' requirements. No single lead-free solder is likely to qualify for all defense and space applications. Therefore, it is important to validate alternative solders for discrete applications. As a result of the need for comprehensive test data on the reliability of lead-free solders, a partnership was formed between the DoD, NASA, and several original equipment manufactures (OEMs) to conduct solder-joint reliability (laboratory) testing of three lead-free solder alloys on newly manufactured and reworked circuit cards to generate performance data for high-reliability (IPC Class 3) applications.

Brown, Christina↗
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 NTRS2010

Facilitating NASA's Use of GEIA-STD-0005-1, Performance Standard for Aerospace and High Performance Electronic Systems Containing Lead-Free Solder

GEIA-STD-0005-1 defines the objectives of, and requirements for, documenting processes that assure customers and regulatory agencies that AHP electronic systems containing lead-free solder, piece parts, and boards will satisfy the applicable requirements for performance, reliability, airworthiness, safety, and certify-ability throughout the specified life of performance. It communicates requirements for a Lead-Free Control Plan (LFCP) to assist suppliers in the development of their own Plans. The Plan documents the Plan Owner's (supplier's) processes, that assure their customer, and all other stakeholders that the Plan owner's products will continue to meet their requirements. The presentation reviews quality assurance requirements traceability and LFCP template instructions.

Plante, Jeannete↗
NASA NTRS2003

Lead-free solders: issues of toxicity, availability and impacts of extraction

This project set out to evaluate the critical issues of toxicity and public health effects, material availability, and the environmental impacts of raw material extraction and metal finishing, with the goal of using environmental impact as a factor in selecting feasible lead-free alloys.

toxicity lead-free solder packaging↗
NASA NTRS2005

Mechanical Properties and Microstructure Investigation of Lead Free Solder

While the electronics industry appears to be focusing on Sn-Ag-Cu as the alloy of choice for lead free electronics assembly, ,the exact composition varies by geographic region, supplier and user. Add to that dissolved copper and silver from the printed circuit board traces and surface finish, and there can be significant variation in the final solder joint composition. A systematic study of the mechanical and microstructural properties of Sn-Ag-Cu alloys with Ag varying from 2wt% to 4wt% and Cu varying from 0.5wt% to lSwt%, was undertaken in this research study. Different sample preparation techniques (water quenched, oil quenched and water quenched followed by reflow) were explored and the resulting microstructure compared to that of a typical reflowed lead free chip scale package (CSP) solder joint. Tensile properties (modulus, 0.2% yield strength and the ultimate tensile strength) and creep behavior of selected alloy compositions (Sn-4Ag-1 X u , Sn-4Ag-OSCu, Sn- 2Ag-1 X u , Sn-2Ag-OSCu, Sn-3.5Ag-O.SCu) were determined for three conditions: as- cast; aged for 100 hours at 125OC; and aged for 250 hours at 125OC. There was no significant difference in Young's Modulus as a function of alloy composition. After an initial decrease in modulus after 100 hours at 125"C, there was an insignificant change with further aging. The distribution of 0.2% strain yield stress and ultimate tensile strength as a function of alloy composition was more significant and decreased with aging time and temperature. The microstructures of these alloys were examined using light and scanning electron microscopy (LM and SEM) respectively and SEM based energy dispersive x-ray spectroscopy (EDS). Fracture surface and cross-section analysis were performed on the specimens after creep testing. The creep testing results and the effect of high temperature aging on mechanical properties is presented for the oil quenched samples. In general the microstructure of oil quenched specimen exhibited a eutectic region of Sn with moderately dispersed Ag3Sn intermetallic, surrounded by a dendritic Sn-rich phase. The SEM images of the fracture surface indicated the presence of a tough shear surface at the initial cavity break area and a break line in the middle of specimen along the failure direction. A hyperbolic-sine creep model was adopted and used to fit the creep experiment data. The effect on the mechanical properties by adding the quaternary element bismuth to the Sn-3.5Ag-0.8Cu alloy was measured and compared with the mechanical properties of the ternary alloys. The results of this research study provide necessary data for the modeling of solder joint reliability for a range of Sn-Ag-Cu compositions and a baseline for evaluating the effects of subsequent quaternary additions.

Wang, Qing↗
NASA NTRS2010

Working with Consortia - Advanced Packaging Reliability

Description: Support the responsible NASA official for lead-free solder evaluation. Serve as the NASA technical liaison to the NASA/DoD Pb-free Project. Assure NASA areas of interest are included in JG-PP follow-on work. Support NASA/DoD telcons and face-to-face meetings. Update MSFC lead-free solder lessons learned report. FY10 plans: - Reliability data on lead-free solder applications for various part lead finishes and board finishes. - Update lead-free solder risks and risk mitigation strategies for NASA. - Evaluate lead-free alloy/lead-free finish reliability in design application. - Status CAVE project on Pb-free solder aging effects. - Compile the LTESE flight and bench data.

Blanche, Jim↗
NASA NTRS2011

Reliability of Sn/Pb and Lead-Free (SnAgCu) Solders of Surface Mounted Miniaturized Passive Components for Extreme Temperature (-185 C to +125 C) Space Missions

Surface mount electronic package test boards have been assembled using tin/lead (Sn/Pb) and lead-free (Pb-free or SnAgCu or SAC305) solders. The soldered surface mount packages include ball grid arrays (BGA), flat packs, various sizes of passive chip components, etc. They have been optically inspected after assembly and subsequently subjected to extreme temperature thermal cycling to assess their reliability or future deep space, long-term, extreme temperature environmental missions. In this study, the employed temperature range (-185oC to +125oC) covers military specifications (-55oC to +100oC), extreme old Martian (-120oC to +115oC), asteroid Nereus (-180oC to +25oC) and JUNO (-150oC to +120oC) environments. The boards were inspected at room temperature and at various intervals as a function of extreme temperature thermal cycling and bake duration. Electrical resistance measurements made at room temperature are reported and the tests to date have shown some change in resistance as a function of extreme temperature thermal cycling and some showed increase in resistance. However, the change in interconnect resistance becomes more noticeable with increasing number of thermal cycles. Further research work will be carried out to understand the reliability of packages under extreme temperature applications (-185oC to +125oC) via continuously monitoring the daisy chain resistance for BGA, Flat-packs, lead less chip packages, etc. This paper will describe the experimental reliability results of miniaturized passive components (01005, 0201, 0402, 0603, 0805, and 1206) assembled using surface mounting processes with tin-lead and lead-free solder alloys under extreme temperature environments.

extreme temperatures,↗
NASA NTRS2010

NASA-DoD Lead-Free Electronics Project

This slide presentation reviews the current state of the lead-free electronics project. It characterizes the test articles, which were built with lead-free solder and lead-free component finishes. The tests performed and reported on are: thermal cycling, combine environments testing, mechanical shock testing, vibration testing and drop testing.

Kessel, Kurt↗
NASA NTRS2005

Lead-Free vs Tin-Lead Reliability of Advanced Electronic Assemblies

This presentation will provide the technical background and specific information published in literature related to reliability test, analyses, modeling, and associated issues for lead-free solder package assemblies in comparison to their tin-lead solder alloys. It also presents current understanding of lead-free thermal cycle test performance in support.

assembly reliability↗
NASA NTRS2016

NASA Collaborative Approach Mitigates Environmentally-Driven Obsolescence

National Aeronautics and Space Administration (NASA) missions, like Department of Defense (DoD) organizations, require the rigorous testing and qualification of critical materials. Obsolescence supply risks created by environmental requirements can affect the cost, schedule and performance of NASA missions and the resilience of critical infrastructure. The NASA Technology Evaluation for Environmental Risk Mitigation (TEERM) Principal Center helps to identify obsolescence supply risks driven by environmental requirements and works proactively with NASA Centers and Programs, the DoD, the European Space Agency (ESA) and other agencies and partners to identify and evaluate environmentally friendly alternatives. TEERM tracks environmental regulations, identifies the potential loss of material availability and works with NASA programs and Centers to evaluate potential impacts through a risk assessment approach. TEERM collaborative projects identify, demonstrate and evaluate commercially viable alternative technologies and materials. A major focus during the Space Shuttle Program was the need to replace ozone depleting substances that were used in spray foam and cleaning applications. The potential obsolescence of coatings containing hexavalent chromium and the risks associated with lead free solder were also of concern for the Space Shuttle and present ongoing risks to new programs such as the Space Launch System. One current project teams NASA and ESA in the evaluation and testing of individual coatings and coating systems as replacements for hexavalent chromium coatings in aerospace applications. The proactive, collaborative approach used by TEERM helps reduce the cost burden on any one team partner, reduces duplication of effort, and enhances the technical quality and overall applicability of the testing and analysis.

environmentall-driven obsolescence↗
NASA NTRS2010

NASA-DoD Lead-Free Electronics Project: Vibration Test

Vibration testing was conducted by Boeing Research and Technology (Seattle) for the NASA-DoD Lead-Free Electronics Solder Project. This project is a follow-on to the Joint Council on Aging Aircraft/Joint Group on Pollution Prevention (JCAA/JG-PP) Lead-Free Solder Project which was the first group to test the reliability of lead-free solder joints against the requirements of the aerospace/miLItary community. Twenty seven test vehicles were subjected to the vibration test conditions (in two batches). The random vibration Power Spectral Density (PSD) input was increased during the test every 60 minutes in an effort to fail as many components as possible within the time allotted for the test. The solder joints on the components were electrically monitored using event detectors and any solder joint failures were recorded on a Labview-based data collection system. The number of test minutes required to fail a given component attached with SnPb solder was then compared to the number of test minutes required to fail the same component attached with lead-free solder. A complete modal analysis was conducted on one test vehicle using a laser vibrometer system which measured velocities, accelerations, and displacements at one . hundred points. The laser vibrometer data was used to determine the frequencies of the major modes of the test vehicle and the shapes of the modes. In addition, laser vibrometer data collected during the vibration test was used to calculate the strains generated by the first mode (using custom software). After completion of the testing, all of the test vehicles were visually inspected and cross sections were made. Broken component leads and other unwanted failure modes were documented.

Woodrow, Thomas A.↗
NASA NTRS2008

Reliability of PWB Microvias for High Density Package Assembly

High density PWB (printed wiring board) with microvia technology is required for implementation of high density and high I/O area array packages (AAP). COTS (commercial off-the-shelf) AAP packaging technologies in high reliability versions with 1.27 mm pitch are now being considered for use in a number of NASA systems including Space Shuttle and Mars Rovers. NASA functional system designs are requiring more and more dense AAP packages and board space, which makes board microvia technology very attractive for effectively routing a large number of package inputs/outputs. However, the reliability of the fine feature microvias including via in pads is unknown for space applications. Understanding process and QA (quality assurance) indicators for reliability are important for low risk insertion of these newly available packages and PWBs. This paper presents literature search as well as test results for a high density board subjected to various thermal cycle and reflow profiles representative of tin-lead and lead-free solder reflow. Microvias sizes ranged from two to six mil with and without filling. Daisy chain microvias monitored during the test and PWBs were cross-sectioned to determine failure and locations. Optical and SEM photographs as well as resistance changes during cycling and Tg/Td (glass transition/decomposition temperature) characterisations are presented.

fill via↗
NASA NTRS2003

Integrated Electrode Arrays for Neuro-Prosthetic Implants

Arrays of electrodes integrated with chip-scale packages and silicon-based integrated circuits have been proposed for use as medical electronic implants, including neuro-prosthetic devices that might be implanted in brains of patients who suffer from strokes, spinal-cord injuries, or amyotrophic lateral sclerosis. The electrodes of such a device would pick up signals from neurons in the cerebral cortex, and the integrated circuit would perform acquisition and preprocessing of signal data. The output of the integrated circuit could be used to generate, for example, commands for a robotic arm. Electrode arrays capable of acquiring electrical signals from neurons already exist, but heretofore, there has been no convenient means to integrate these arrays with integrated-circuit chips. Such integration is needed in order to eliminate the need for the extensive cabling now used to pass neural signals to data-acquisition and -processing equipment outside the body. The proposed integration would enable progress toward neuro-prostheses that would be less restrictive of patients mobility. An array of electrodes would comprise a set of thin wires of suitable length and composition protruding from and supported by a fine-pitch micro-ball grid array or chip-scale package (see figure). The associated integrated circuit would be mounted on the package face opposite the probe face, using the solder bumps (the balls of the ball grid array) to make the electrical connections between the probes and the input terminals of the integrated circuit. The key innovation is the insertion of probe wires of the appropriate length and material into the solder bumps through a reflow process, thereby fixing the probes in place and electrically connecting them with the integrated circuit. The probes could be tailored to any distribution of lengths and made of any suitable metal that could be drawn into fine wires. Furthermore, the wires could be coated with an insulating layer using anodization or other processes, to achieve the correct electrical impedance. The probe wires and the packaging materials must be biocompatible using such materials as lead-free solders. For protection, the chip and package can be coated with parylene.

Brandon, Erik↗
DOE OSTI2024

Rapid Predictions of Part Lifetimes in Corrosive Environments, Corrosion

Corrosion challenges persist throughout SNL’s mission areas. The primary difficulty lies in the fact that corrosion typically manifests as isolated, rare events, making preemptive identification exceedingly difficult. Our current strategy for addressing corrosion issues, such as anomalies and SFIs, is similarly isolated and reactive. This method is costly, time-consuming, heavily dependent on a limited number of experts, and offers minimal understanding of the overall damage distribution within the stockpile. This technical challenge is not unique to corrosion but is also prevalent in other material aging phenomena, such as tin-whisker growth in lead-free solder and fatigue failure of springs.

36 MATERIALS SCIENCE↗