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NASA NTRS2018

Achieving Improved Reliability with Failure Analysis

Reliability is the ability of a product to properly function, within specified performance limits, for a specified period of time, under the life cycle application conditions. Failure analysis is a vital tool in the effort to ensure reliability of electronic products and systems throughout their product lifecycle. Today, organizations involved in activities within the electronics supply chain are facing new challenges, not just from complex assembly styles, harsher lifecycle environments, and sophisticated supply chains, but also from customers who are demanding a quicker turn-around. Unfortunately, root cause failure analysis is often performed incompletely, leading to a poor understanding of failure mechanisms and causes and, customer dissatisfaction due to recurring failures. The PDC starts with an introduction to reliability concepts, physics of failure and an overview of failure mechanisms that affect PCBs, PCBAs and components. The PDC then dives into root cause hypothesizing techniques (Pareto, FMEA, fishbone, FTA), non-destructive and destructive analysis and, materials characterization will be discussed. Numerous 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. What Will You Learn: Topics include: Overview of Reliability Concepts Failure mechanisms of electronic products Root cause analysis Failure analysis techniques -Non-destructive techniques (optical, CSAM etc.) -Destructive analysis (DPA, Decap, FIB etc.) -Materials characterization (XRF, EDS, TMA/DSC etc.) Who Will Benefit: Reliability engineers, failure analysis engineers, engineering managers, design engineers, component engineers, quality assurance functions and, personnel involved with reliability activities within their company.

non-destructive techniques↗

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 NTRS2019

Achieving Improved Reliability with Failure Analysis

Reliability is the ability of a product to properly function, within specified performance limits, for a specified period of time, under the life cycle application conditions. Failure analysis is a vital tool in the effort to ensure reliability of electronic products and systems throughout their product lifecycle. Today, organizations involved in activities within the electronics supply chain are facing new challenges, not just from complex assembly styles, harsher lifecycle environments, and sophisticated supply chains, but also from customers who are demanding a quicker turn-around. Unfortunately, root cause failure analysis is often performed incompletely, leading to a poor understanding of failure mechanisms and causes and, customer dissatisfaction due to recurring failures. The PDC (Professional Development Course) starts with an introduction to reliability concepts, physics of failure and an overview of failure mechanisms that affect PCBs (Printed Circuit Boards), PCBAs (Printed Circuit Board Assembly) and components. The PDC then dives into root cause hypothesizing techniques (Pareto, FMEA (Failure Modes and Effects Analysis), fishbone (Cause-And-Effect Diagram), FTA (Fault Tree Analysis)), non-destructive and destructive analysis and, materials characterization will be discussed. Numerous 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. What Attendees will Learn: Topics include: Overview of Reliability Concepts Failure mechanisms of electronic products Root cause analysis Failure analysis techniques -Non-destructive techniques (optical, CSAM (Confocal Scanning Electron Microscopy) etc.) -Destructive analysis (DPA (Destructive Physical Analysis), Decap (Decapsulation), FIB (Focused Ion Beam) etc.) -Materials characterization (XRF (X-Ray Fluorescence) , EDS (Error Detection Sequential), TMA/DSC (Thermal Mechanical Analysis/Differential Scanning Calorimetry) etc.)

PCB quality↗

NASA NTRS1996

JPL/NASA/IEEE Test Effectiveness Workshop

(none given)From OBJECTIVES: Specific objectives of the working group are to support the innovation, development, evaluation and implementation of test methods, metrics and tools based on failure engineering/physics and/or root cause evaluations. Data sources systems and tools shall be developed and implemented that: 1) provide improved preventions, controls, analyses and tests (PACT) & field failure data collection, 2) facilities data analysis, archiving, retrieval, failure physics and/or root cause evaluations and 3) enable new and existing technology suitability evaluations to be performed.

effectiveness concurrent engineering metrics test ↗

DOE OSTI2025

Investigation of the Effect of Gate Oxide Screening with Adjustment Pulse on Commercial SiC Power MOSFETs

This paper presents a method to recover the negative threshold voltage shift during high field gate oxide screening of 1.2 kV 4H-SiC MOSFETs with an additional adjustment gate voltage pulse. To reduce field failure rates of the MOSFETs in operation, manufacturers perform a screening treatment to remove devices with extrinsic defects in the oxide. Current gate oxide screening procedures are limited to oxide fields at or below ~9 MV/cm for short durations (<1 s), which is not enough to remove all the devices with extrinsic defects. The results show that by implementing a lower field gate pulse, the threshold voltage shift can be partially recovered, and therefore the maximum screening field and time can be increased. However, both the initial screening pulse and the adjustment pulse require careful calibration to prevent significant degradation of the device threshold voltage, on-resistance, interface state density, or intrinsic lifetime. With a well calibrated set of pulses, higher screening fields can be utilized without significantly damaging the devices. This leads to an improvement in the overall screening efficiency of the process, reducing the number of devices with extrinsic oxide defects entering the field, and improving the reliability of the SiC MOSFETs in operation.

42 ENGINEERING↗

DOE OSTI2012

Impact of Consolidation Radiation Therapy in Stage III-IV Diffuse Large B-cell Lymphoma With Negative Post-Chemotherapy Radiologic Imaging

Purpose: While consolidation radiation therapy (i.e., RT administered after chemotherapy) is routine treatment for patients with early-stage diffuse large B-cell lymphoma (DLBCL), the role of consolidation RT in stage III-IV DLBCL is controversial. Methods and Materials: Cases of patients with stage III-IV DLBCL treated from 1991 to 2009 at Duke University, who achieved a complete response to chemotherapy were reviewed. Clinical outcomes were calculated using the Kaplan-Meier method and were compared between patients who did and did not receive RT, using the log-rank test. A multivariate analysis was performed using Cox proportional hazards model. Results: Seventy-nine patients were identified. Chemotherapy (median, 6 cycles) consisted of anti-CD20 antibody rituximab combined with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP; 65%); cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP; 22%); or other (13%). Post-chemotherapy imaging consisted of positron emission tomography (PET)/computed tomography (CT) (73%); gallium with CT (14%); or CT only (13%). Consolidation RT (median, 25 Gy) was given to involved sites of disease in 38 (48%) patients. Receipt of consolidation RT was associated with improved in-field control (92% vs. 69%, respectively, p = 0.028) and event-free survival (85% vs. 65%, respectively, p = 0.014) but no difference in overall survival (85% vs. 78%, respectively, p = 0.15) when compared to patients who did not receive consolidation RT. On multivariate analysis, no RT was predictive of increased risk of in-field failure (hazard ratio [HR], 8.01, p = 0.014) and worse event-free survival (HR, 4.3, p = 0.014). Conclusions: Patients with stage III-IV DLBCL who achieve negative post-chemotherapy imaging have improved in-field control and event-free survival with low-dose consolidation RT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

DOE OSTI2015

A practical approach to reconciling availability, performance, and capacity in provisioning extreme-scale storage systems

The increasing data demands from high-performance computing applications significantly accelerate the capacity, capability and reliability requirements of storage systems. As systems scale, component failures and repair times increase, significantly impacting data availability. A wide array of decision points must be balanced in designing such systems. We propose a systematic approach that balances and optimizes both initial and continuous spare provisioning based on a detailed investigation of the anatomy and field failure data analysis of extreme-scale storage systems. We consider the component failure characteristics and its cost and impact at the system level simultaneously. We build a tool to evaluate different provisioning schemes, and the results demonstrate that our optimized provisioning can reduce the duration of data unavailability by as much as 52% under a fixed budget. We also observe that non-disk components have much higher failure rates than disks, and warrant careful considerations in the overall provisioning process.

Computer Science↗

DOE OSTI2015

Combustion Safety Simplified Test Protocol Field Study

Combustions safety is an important step in the process of upgrading homes for energy efficiency. There are several approaches used by field practitioners, but researchers have indicated that the test procedures in use are complex to implement and provide too many false positives. Field failures often mean that the house is not upgraded until after remediation or not at all, if not include in the program. In this report the PARR and NorthernSTAR DOE Building America Teams provide a simplified test procedure that is easier to implement and should produce fewer false positives. A survey of state weatherization agencies on combustion safety issues, details of a field data collection instrumentation package, summary of data collected over seven months, data analysis and results are included. The project team collected field data on 11 houses in 2015.

Building America↗

DOE OSTI2022

A study of degradation mechanisms in PVDF-based photovoltaic backsheets

Abstract Commercial backsheets based on polyvinylidene fluoride (PVDF) can experience premature field failures in the form of outer layer cracking. This work seeks to provide a better understanding of the changes in material properties that lead to crack formation and find appropriate accelerated tests to replicate them. The PVDF-based backsheet outer layer can have a different structure and composition, and is often blended with a poly(methyl methacrylate) (PMMA) polymer. We observed depletion of PMMA upon aging with sequential (MAST) and combined (C-AST) accelerated stress testing. In field-aged samples from Arizona and India, where PVDF crystallizes in its predominant α-phase, the degree of crystallinity greatly increased. MAST and C-AST protocols were, to some extent, able to replicate the increase in crystallinity seen in PVDF after ~ 7 years in the field, but no single-stress test condition (UV, damp heat, thermal cycling) resulted in significant changes in the material properties. The MAST regimen used here was too extreme to produce realistic degradation, but the test was useful in discovering weaknesses of the particular PVDF-based outer layer structure studied. No excessive β-phase formation was observed after aging with any test condition; however, the presence of β-phase was identified locally by Fourier transform infrared spectroscopy (FTIR). We conclude that both MAST and C-AST are relevant tests for screening outdoor failure mechanisms in PVDF backsheets, as they were successful in producing material degradation that led to cracking.

14 SOLAR ENERGY↗

DOE OSTI2015

NREL/NASA Internal Short-Circuit Instigator in Lithium Ion Cells

NREL has developed a device to test one of the most challenging failure mechanisms of lithium-ion (Li-ion) batteries -- a battery internal short circuit. Many members of the technical community believe that this type of failure is caused by a latent flaw that results in a short circuit between electrodes during use. As electric car manufacturers turn to Li-ion batteries for energy storage, solving the short circuit problem becomes more important. To date, no reliable and practical method exists to create on-demand internal shorts in Li-ion cells that produce a response that is relevant to the ones produced by field failures. NREL and NASA have worked to establish an improved ISC cell-level test method that simulates an emergent internal short circuit, is capable of triggering the four types of cell internal shorts, and produces consistent and reproducible results. Internal short circuit device design is small, low-profile and implantable into Li-ion cells, preferably during assembly. The key component is an electrolyte-compatible phase change material (PCM). The ISC is triggered by heating the cell above PCM melting temperature (presently 40 degrees C -- 60 degrees C). In laboratory testing, the activated device can handle currents in excess of 300 A to simulate hard shorts (< 2 mohms). Phase change from non-conducting to conducting has been 100 percent successful during trigger tests.

25 ENERGY STORAGE↗

DOE OSTI2015

Technology Solutions Case Study: Combustion Safety Simplified Test Protocol

Building America↗

DOE OSTI2017

Tracking Internal Temperature and Structural Dynamics during Nail Penetration of Lithium-Ion Cells

Mechanical abuse of lithium-ion batteries is widely used during testing to induce thermal runaway, characterize associated risks, and expose cell and module vulnerabilities. But, the repeatability of puncture or 'nail penetration' tests is a key issue as there is often a high degree of variability in the resulting thermal runaway process. Here, the failure mechanisms of 18650 cells punctured at different locations and orientations are characterized with respect to their internal structural degradation, and both their internal and surface temperature, all of which are monitored in real time. The initiation and propagation of thermal runaway is visualized via high-speed synchrotron X-ray radiography at 2000 frames per second, and the surface and internal temperatures are recorded via infrared imaging and a thermocouple embedded in the tip of the penetrating nail, respectively. The influence of the nail, as well as how and where it penetrates the cell, on the initiation and propagation of thermal runaway is described and the suitability of this test method for representing in-field failures is discussed.

25 ENERGY STORAGE↗

DOE OSTI2026

Towards Commercialization of Low-Cost, Crack-Tolerant, Screen-Printable Metallization by Full-Size Module Testing and Field Characterization

This project is motivated by the need to develop a materials engineering solution to reduce solar module degradation caused by cell cracks. The cell-crack-induced power loss is a long-term degradation mechanism and one of the main causes of solar panel field failures. Cell cracks can occur during module fabrication, transportation, installation, and long-term operation due to thermomechanical stressors. Our team’s internal estimation – based on the national weather pattern, frequency of severe weather, and 39- GW asset survey by Heliolytics – reveals that the cell-crack-induced module degradation translates to lost revenues >$17B over an average 5-year period for solar farm owners and to reduced reliability (<25 years panel lifetime) for solar energy consumers. In response to this challenge, the prime recipient offers a metal matrix composite (MMC) silver paste that is tailor-engineered for screen-printing gridlines and busbars, which serve as the electrical contacts on solar cells. We formulate our MMC paste by adding low-cost (∼0.02¢/WDC for research grade), surface-engineered carbon nanotubes to commercially available silver paste. The MMC paste offers a drop-in, cost-effective solution to cell cracks for solar cell and module manufacturers. The main goal of this project was to conduct field-relevant, module-level analysis and qualification of MMC metallization.

14 SOLAR ENERGY↗

DOE OSTI2019

Decoupling of heat generated from ejected and non-ejected contents of 18650-format lithium-ion cells using statistical methods

Effective thermal management systems, designed to handle the impacts of thermal runaway (TR) and to prevent cell-to-cell propagation, are key to safe operation of lithium-ion (Li-ion) battery assemblies. Critical factors for optimizing these systems include the total energy released during a single cell TR event and the fraction of the total energy that is released through the cell casing versus through the ejecta material. A unique fractional thermal runaway calorimeter (FTRC), designed to characterize said critical factors, was utilized to examine the TR behavior of 18650-format Li-ion cells representing a variety of manufacturers, chemistries, capacities, and safety features. Primarily, the impacts of bottom vent (BV) safety features, varied cell casing thickness, and Dreamweaver cellulose based separators were assessed for select cell types. A subset of cells also had an imbedded internal short circuiting (ISC) device to allow examination of TR behavior initiated at lower temperatures (i.e. closer to field failure conditions). The impact of bottom rupture on TR behavior was also examined for experiments that resulted in this non-standard failure mechanism. Statistical analysis of the results for each cell configuration reveals that a lognormal distribution effectively characterizes the variation of total TR energy release. Typically 20%-30% of the total energy yield is released through the cell casing with the remainder through the ejecta material. Higher energy cells tend to exhibit more violent ejections and less predictable TR events. Inclusion of a BV feature reduces the overall severity of the TR event and can increase the predictability. Results also suggest that the magnitude of the TR event may not be directly proportional to the stored electrical energy, but rather has additional dependence on other design and failure mode factors.

25 ENERGY STORAGE↗

DOE OSTI2021

Evaluating Non-Fluoropolymer-Based Co-Extruded Backsheets Using Combined-Accelerated Stress Testing and Materials Forensics

Co-extruded, non-fluoropolymer backsheet films for photovoltaic (PV) modules have gained popularity in recent years based on their cost competitiveness. However, their viability has been thrown into question as a result of widespread, early-life field-failures of some materials, particularly the polyamide (PA)-based “AAA” backsheet product. Failure to detect weaknesses in those earlier products could be due, in part, to insufficient quality testing practices. New testing protocols have recently been developed to better evaluate such materials. Here we show the testing results for a non-fluoropolymer, co-extruded PA-based backsheet film, which demonstrates greater durability than AAA and some commercial fluoropolymers. Using material characterization techniques including Fourier-transform infrared spectroscopy (FTIR), wide-angle x-ray scattering (WAXS), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), elongation-to-break (ETB), and optical microscopy we perform a comprehensive failure analysis to better understand the materials weaknesses. This analysis can ultimately inform how best to improve the material and extend its lifetime. This work serves as a demonstration that some materials should not be discounted due to a single poorly designed product and that more appropriate qualification testing with subsequent materials analysis can be used to develop better materials.

41 EE - Solar Energy Technologies Office (EE-4S)↗

DOE OSTI2020

Understanding Li-Ion Cell Internal Short Circuit and Thermal Runaway through Small, Slow and In Situ Sensing Nail Penetration

Here we report a small, slow and in situ sensing (3S) nail penetration test method to understand Li-ion cell internal short circuit (ISC) and thermal runaway. The method not only keeps conventional nail penetration's advantage of simple implementation, but also enhances its relevance to field failures and enables detailed in situ diagnosis. It was applied to 3-Ah pouch cells and revealed insights that could not be captured by conventional methods. Most interestingly, multiple in situ temperature peaks were observed during a period of over 100 s before thermal runaway. These initial peaks exceeded safety limit but the temperature rapidly decreased after each peak instead of causing immediate thermal runaway. Further investigation suggested that the initial temperature peaks occurred when nail tip reached aluminum foil current collector to form a low resistance ISC between anode and aluminum foil. The rapid temperature decrease after each peak can be attributed to sudden drop of ISC current, which can be further attributed to rupture of aluminum foil and increase of contact resistance. The findings show that 3S nail penetration test can separate processes of ISC from thermal runaway and provide details of ISC at the level of individual electrode and current collector.

25 ENERGY STORAGE↗

DOE OSTI2019

Vertical Axis Wind Turbine (VAWT) with Thermoplastic Composite Blades

Rising concerns about global climate change, planet pollution and increasing use of energy have accelerated wider utilization of renewable energy sources. A recent trend in energy system development is decentralization of power generation systems. The opportunity for individuals or organizations to generate electricity locally decreases losses and part of the electricity price caused by the long-distance power transmission. Vertical axis wind turbines (VAWTs) cannot compete with traditional horizontal axis wind turbines (HAWTs) on the basis of aerodynamic performance or maximum power output generated for a given footprint. However, their ability to perform at a wide range of wind speeds, indifference to wind direction, simplicity of fabrication, transportability and maintainability make them ideal candidates for decentralized installations in urban and residential areas. The project team including Steelhead Composites (SHC), Colorado State University (CSU), National Renewable Energy Laboratory (NREL) and Arkema Inc. designed and fabricated a VAWT rotor assembly with thermoplastic composite blades using novel infusion and fabrication techniques. This full-scale VAWT rotor assembly was designed for a rated power output of 0.5-1 kW, as estimated through analytical computational fluid dynamics (CFD) methods. Those CFD simulations were combined with structural finite element analysis (FEA) to optimize the shape and composite layup of the wind blades. Much of the emphasis of this program was to characterize the recyclable thermoplastic material and composite structural design, in order to take full advantage of the material properties of such composites. Additionally, this project examined the potential of thermoplastic resin systems to transform the way VAWT rotor assemblies are joined both in the factory in in the field, by utilizing thermally welded joints to minimize field failure. The infused composite blades manufactured during this program are an excellent example of these benefits made possible by the Arkema thermoplastic resin system. This prototype blade manufacturing also provided the groundwork to inform decisions for larger scale manufacturing techniques applicable to a commercialization strategy. There is specific commercial interest for small scale VAWT’s that are competitively priced, perform to expectations, and have environmentally conscious end-of-life characteristics. Economic analysis was also conducted to compare designs and material usage, providing an estimated levelized cost of energy (LCOE) for the VAWT. The next steps for commercialization would include testing of the rotor assembly to verify predicted performance, specification of the balance of plant components (generator, inverter, etc.), and identification of a manufacturing partner with capability to scale-up production. This program has showed the potential for a commercially viable product through detailed analysis, material characterization and prototype fabrication.

17 WIND ENERGY↗

DOE OSTI2020

bifiPV2020 Bifacial Workshop: A Technology Overview

The virtual bifiPV Workshop was held in July 2020 to provide the solar industry with a forum for sharing and discussing research into bifacial photovoltaic (PV) technology. This report outlines major insights from the workshop to give the reader an overview of the latest developments in bifacial PV technology worldwide, from the lab to the field. Citations are drawn from this workshop unless otherwise noted, with all proceedings available online at bifipvworkshop. com. Presentations for the bifiPV2020 Workshop focused on the following areas: bifacial power plant modeling and simulation, albedo improvements, the development of encapsulants, the durability and reliability of current bifacial technologies, performance comparisons between glass-glass and glass-transparent backsheet configurations, the future of passivated emitter and rear contact (PERC) solar cells, and the growing adoption of n-type solar cells. With 650 GW total PV installed worldwide and 1 TW to come very soon, PERC is now the standard PV cell type produced en masse. However, it is already reaching 23% efficiency, the upper limit for this type of technology. PV modules breaking the 0.5-kW barrier are starting to appear, and the costs of standard PERC technology are already below 0.2 USD/Wp. In 2019, five GW of bifacial PV were installed worldwide. In 2020, the majority of bifacial installations are expected to be located in the United States, China, and Middle East and North Africa (MENA) states. N-type bifacial technologies are becoming increasingly viable and have huge potential to dominate the market in the coming years. With bifacial technology mounted on horizontal single-axis trackers (HSAT), bids below 10 USD/MWh will soon be observed in the MENA region, and later in Chile and the United States. Factory audits and reliability testing can reduce field failures by helping buyers to select producers that follow rigorous quality assurance and quality control processes.

14 SOLAR ENERGY↗