bluuebunny/crossref_metadata_2025 huggingface dataset:
A Method for Cross Calibrating Particle Counters
Authors: Dahneke Barton , Johnson Bradley
Published: November 2020

A system for generating participate air contamination standards of known size distribution and concentration was developed and used to determine the accuracy of several optical particle counters (OPCs) for the measurement of paniculate air contamination. Of particular concern was the substantial instrument-to-instrument variability of up to a factor of six or more sometimes observed when measuring the same sample with two similar instruments. We found that while the agreement between two instruments calibrated from the manufacturer's calibration data was sometimes poor, the same instruments calibrated by our methods agreed within 10% in their measured results. We therefore recommend use of these new calibration methods when precise air contamination measurements or interchangeability of instruments are needed.
Shock Simulation and Testing in Weapons Development
Authors: Jones M.
Published: November 2020

A large number and variety of shock/transient acceleration loading cases are encountered in the service lives of weapon systems. The realistic, cost effective simulation of cases ranging from handling through launch to terminal impact presents many problems, but is essential to guarantee performance, safety and reliability of individual systems and components. This paper shows how relatively simple air gun techniques used in conjunction with a safe test cell can significantly enhance the realism, scope and scale of simulation. Developments in the techniques have resulted particularly from the use of modular construction methods, and the application of modern microcomputer and instrumentation methods.

In practice, the techniques described have evolved over many years at the author's company, driven by requirements from a wide range of weapons projects. Typical examples of applications from direct experience are given, including rocket motor launch simulation, flight retarder load simulation, pyrotechnic separation shock simulation, multiple ejection and angled impact.
Reliability Testing—Challenges and Trends
Authors: Chenoweth Halsey
Published: November 2020

Recent advances in reliability testing during the last two decades have started the process of changing the perspective of the reliability community toward this form of testing. This paper briefly examines the range of reliability testing concepts with a concentration of reliability growth testing. These concepts offer a challenge to the product reliability community with relation to the sequence and types of reliability testing currently in use by the community.
Construction and Activation of Rockwell International's Acoustic Test Chamber
Authors: Kamei Lawrence
Published: November 2020

Rockwell International's Satellite Systems Division in Seal Beach recently completed a plant modernization program to support the mass production of 28 satellites. The modernization program consisted of multiple satellite integration and test stations and environmental test facilities, which included a high intensity acoustic test chamber, contained within a 4,645 m2 (50,000 ft2) cleanroom. This paper discusses the design philosophy, construction, integration, and activation of the high intensity acoustic test chamber for production acceptance testing of satellites.

The 906m3 (32,000 ft3) acoustic test cell consists of a steel reinforced concrete chamber with six electropneumatic noise generators. One of the innovative features of the chamber is a unique quarter hom assembly that acoustically couples the noise generators to the chamber. Design concepts, model testing, and evaluation results are presented in the paper. Considerations such as nitrogen versus compressed air source, digital closed loop spectrum control versus manual equalizers, and microprocessor based interlock systems are included in the discussion. Construction difficulties, anomalies encountered, and their resolution are also discussed. Results of the readiness demonstration testing are highlighted, and the paper concludes with illustrations and discussion of the first series of tests performed in the test cell.
The Liege Vacuum Optical Bench ‘Focal 5’
Authors: Macau-Hercot D. , Cucchiaro A. , Macau J. , Jamar J. , Jamar C.
Published: November 2020

Focal is a facility designed to perform optical tests on payloads in a thermal vacuum space environment. The vacuum chamber is a vessel of horizontal cylindrical shape having 5 m (16.4 ft) diameter and 6 m (19.7 ft) length. The vacuum limit is about 1 nbar. Inside the vessel an optical table ensures a stability better than 10 μg. A thermal environment is simulated by shrouds specific to each experiment. The thermal facilities allow the feeding and control of 10 independent shrouds at 10 different temperatures between 170K (-153°F) and 370K (206°F) with a stability of 0.1 K (0.18°F). This facility has been used for the thermal vacuum and thermal balance tests of the ESA Hipparcos astrometry payload.
Analytical Approach for Managing Wastewater Treatment Facility Influent
Authors: Huang D. , Jagodzinski Norbert
Published: November 2020

The objective of this study is to develop methods for efficiently monitoring and effectively controlling wastewater treatment facility influent characteristics. Extreme Value Statistics are used to identify the upper rejectable process level of wastewater parameters, and subsequently in constructing an acceptance control chart with selected risks for managing loads to the industrial wastewater treatment facility.
An Environmental Engineering Management Program for Military Hardware Acquisition
Authors: Sasson Pnina , Elmalah Eli
Published: November 2020

This paper presents an Environmental Engineering Management Program (EEMP) based on the requirements of Section 4 of MIL-STD-810D, as implemented at ADA, ISRAEL. The aims of the EEMP are to:

a. Provide project management with an overall view of the environmental engineering effort; testing costs, manpower and test equipment requirements

b. Assure efficient involvement of the environmental engineering activity in project plans

c. Assure an efficient test plan that considers budget, schedule and other limitations, and

d. Enable systematic collection of important data during the course of the testing.
Vibration Testing Using Spectra with 20 to 50 Breakpoints
Authors: Edelstein Arthur , DeWinter Ray
Published: November 2020

This paper discusses the approach used by engineers at National Technical Systems to perform vibration testing on three Space Shuttle components in 1982 and 1983. All three programs involved sinusoidal, random, and combined sinusoidal/random vibration, with the random vibration in some cases involving high numbers of break-points and some programs requiring applied temperature and/or pressure in addition to the applied vibration. Each test program is briefly summarized in terms of specific requirements, after which the technical difficulties and technical solutions are discussed. Equipment schematics and sample test data in the form of x-y plots are also presented.
SRS—Spreadsheet Response Spectrum
Authors: Pardoen Gerard
Published: November 2020

LOTUS 1-2-3, one of the most popular microcomputer programs, is an integrated spreadsheet, database, and graphics program for organizing and analyzing data in many useful ways. Whereas many 1-2-3 applications tend to be business oriented, a substantial base of engineering software utilizes 1-2-3. The spreadsheet demonstrates how this ubiquitous microcomputer program can be used to perform response spectrum calculations.
Evaluation of Critical Gas-Line Filters
Authors: Jensen David , Goldsmith Susan
Published: November 2020

Gas-line filters are in widespread use in critical semiconductor manufacturing equipment and process lines. In this study, we developed accurate test methods for evaluation of these filters for particulate cleanliness during both steady flow and mechanical shock. Each test method and apparatus is described, and choice of testing conditions are discussed. Filters from four major manufacturers were evaluated and the data are shown and compared.
Spacecraft Internal Vibration Response Accelerations System Level Versus Component Level
Authors: Judkins N. , Ranaudo Susan
Published: November 2020

The purpose of this study was to compare vibration damage potential with damage potential during the spacecraft level acoustic exposure. A spacecraft simulator and the instrumented component were exposed to a typical spacecraft level acoustic environment. The panel response data were then enveloped to define a random vibration environment, which was subsequently applied to the same component, hard-mounted to an electrodynamic shaker. A comparison of the internal responses obtained during the acoustic test with those of the vibration test determined that the vibration test generally had accelerations approximately five times those of the acoustic test.
Characteristics of Ultra-High Efficiency Membrane Filters in Gas Applications
Authors: Rubow Kenneth , Liu Benjamin , Grant Donald
Published: November 2020

The particle collection characteristics of ultra-high efficiency polyvinylidene fluoride (PVDF) membrane filter media has been evaluated. This media is typical of PVDF and polytetrafluoroethylene (PTFE) media used for process gas filtration in the semiconductor industry. Testing was performed using specially prepared ultra-thin membrane samples since the penetration through the standard production media is less than current detection limits. The data obtained were used to predict the performance of the standard membrane. The calculated aerosol penetration through the standard media ranges between 6 × 10-32 and 4 × 10-23 for face velocities of 5 to 50 cm/sec. The most penetrating particle size was found in the 0.035 to 0.045 μm size range. The effect of particle loading on particle penetration was also studied. The penetration was found to decrease as the filter media was loaded with either liquid or solid particles.
Ice Is Ice?
Authors: Toliver Richard
Published: November 2020

MIL-STD-810D, Method 521.0, "Icing/Freezing Rain," contains guidance for testing equipment exposed to freezing rain. This method was developed around a narrow set of meteorological conditions resulting in the buildup of clear glaze ice. The icing procedures described in Method 521.0 can be applied to a wide range of equipment and will help to predict equipment operations during natural freezing rain. However, the procedures do not give any indication of the operation of equipment during exposure to rime ice. The physical properties of rime and glaze ice differ significantly, as do their effects on equipment. Until MIL-STD-810D is modified to include rime icing, program managers and environmental test engineers will find no guidance or procedures in MIL-STD-810D for half of the icing (rime vs. glaze) that equipment can be exposed to in nature.
A Production Approach to Environmental Acceptance Testing of Space Vehicle Subsystems
Authors: Jackola Arthur , Allen John
Published: November 2020

Rockwell International's Multi-Environment Test System (METS) is an environmental simulation facility for thermal cycle and thermal vacuum testing of space vehicle subsystems. The use of a central cryopump and eight radially mounted, independently controlled, test chambers provide test efficiencies not possible in single chamber test systems. Thermal cycle and thermal vacuum testing can be performed in each chamber and thereby further increase the efficiency of the test system.

This article describes the Multi-Environment Test System and its configuration and control system and summarizes its use to support black-box environmental test programs.
Optimization of Membranes in High Purity Water Systems for Semiconductor Manufacturing
Authors: Hango Roy
Published: November 2020

Large volumes of ultrapure water are required for semiconductor manufacturing at IBM's Essex Junction, Vermont facility. To produce this water, numerous stages of treatment are required.

Cost savings have been realized by improving the membrane units at several stages. This presentation outlines the experiences and quality for the optimum system and the test methods to verify the performance.
Particles in High Pressure Cylinder Gases: Gas to Particle Conversion During Expansion
Authors: Periasamy Ravindran , Chen Fu-Lin , Ensor David , Donovan Robert , Denyszyn Robert
Published: November 2020

The formation of ultrafine particles by gas to particle conversion is hypothesized to explain the large concentration of ultrafine particles measured downstream of pressure reducing devices on cylinder gases of helium, nitrogen, and argon. These high concentrations of ultrafine particles can be reduced by the insertion of an appropriate purifying stage upstream of the pressure reducing device.
The Behavior of Outgassed Materials in Thermal Vacuums
Authors: Mahone William , Kays Randy
Published: November 2020

Scientists at the NASA White Sands Test Facility (WSTF) are investigating the relationship between outgassing and condensation for aerospace materials in space-like environments. The WSTF throughput test method was validated by previous testing at WSTF using palmitic acid. Data from these tests were compared with data from other preliminary tests by using adipic and behenic acids. The comparison indicates that surface forces between outgassed molecules and the condensing surfaces cause the condensation flux to be different from the incident flux. These forces can also cause the evaporative flux to be different from the expected value. These discrepancies are discussed in terms of both potential and dynamic interactions of outgassed molecules with surfaces. Although these surface forces are noticeable, their overall effect on the test is minimal.
Validation of LACE Spacecraft Vibroacoustic Prediction Model
Authors: Salzberg Aaron
Published: November 2020

The purpose of this article is threefold:

• To verify that the VibroAcoustic Payload Environment Prediction System (VAPEPS), as developed by the Lockheed Missile and Space Company and monitored by the Jet Propulsion Laboratory (JPL), is a viable means of predicting spacecraft component responses to an acoustic environment.

• To address the determination of important parameters in the creation of a Statistical Energy Model in order to achieve accurate results using VAPEPS.

• To present a technique for deriving component random vibration test levels from these results.
Effects of Airborne Pollutants on Deterioration and Aging Behavior of Materials
Authors: Ziegahn Karl-Friedrich , Krause Horst , Schmitt Diether
Published: November 2020

Among natural atmospheric influences, gaseous pollutants effect the deterioration of working materials and technical products. Recent calculations estimate the total cost of material damage caused by pollutants to be several billion dollars (US) annually in the Federal Republic of Germany. More precise calculations are not available because there is a lack of information about the contribution of airborne pollutants.

In combination with humidity, temperature and solar radiation pollutants like sulfur dioxide (SO2), nitric oxide (NOx) and ozone (O3) act onto surfaces of materials exposed to the atmosphere, especially stone, glass, paint coatings, and modern polymeric materials.

This article deals with the results of a study sponsored by the German, Federal Agency for the Environment (Umweltbundesamt). The experimental weathering of some polymers under laboratory conditions will be described in detail. The test items are exposed in pollution chambers to changes in temperature, humidity, solar radiation with and without single and mixed pollutants. The concentrations used (5000 μg/m3 SO2, 5000 μg/m3 NOx, and 2500 μg/m3 O3), were one order of magnitude higher than those measured in industrial areas. The duration of exposure was more than 2 yrs. A projected network of free weathered test sites at different places in Germany served as a reference.
Towards Federal Standard 209E: Partial Versus Complete Inspection of Clean Air Zones
Authors: Cooper Douglas
Published: November 2020

Federal Standard 209D (FED-STD-209D) for certifying the cleanliness of air in cleanrooms requires sampling at a minimum number of locations as determined by the Class Limit and the area of the flow. Gas sampling particle counters are used to sample only part of the area through which gas is flowing. When used in this way, they are carrying out a partial inspection sample, rather than a complete inspection. It is difficult to determine the area of flow to be associated with this point sample. Given the partial, rather than complete nature of the sample, the statistics of partial inspection sampling should be used. This approach can reduce the number of samples needed to ensure adequate gas cleanliness, especially when used to supplement more complete inspection.
Ultra High Bypass Aircraft Sonic Fatigue
Authors: Lorch Daniel
Published: November 2020

The development of the Ultra High Bypass (UHB) engine for transport aircraft introduces sonic fatigue as a major structural design challenge. UHB engines generate high intensity acoustic tones associated with the harmonics of the propeller blades. Current analysis methods and structural design approaches to prevent sonic fatigue cracks are based on techniques developed in the 1960s for broadband random jet-noise excitation.

The high intensity noise testing and analysis completed to develop a sonic fatigue treatment design for the UHB Demonstrator aircraft are discussed. The evaluation included progressive wave tube (PWT) and shaker table testing conducted on representative aircraft components in the laboratory.

Also discussed are the sonic fatigue treatment designs developed and flight tested on the UHB Demonstrator aircraft by Douglas Aircraft Company. The tests proved that lightweight and inexpensive treatments can be developed that will provide protection against sonic fatigue.
Class 100 Large Spacecraft Facility
Authors: Maruya Keith , Ryan Lorraine , Fritz Donald
Published: November 2020

To enhance its competitive edge in producing highly contamination-sensitive space systems, TRW has recently designed and constructed a large spacecraft assembly and test facility that is fully cleanroom compatible. Features of this facility include a large assembly and test area and a smaller support room that have HEPA-filtered vertical flow, dedicated staging areas for garment application, storage, and equipment preparation, and an automated cleanroom monitoring system (CRMS). A description of the design, construction, and certification process is given. Operational data from the CRMS and lessons learned are also presented.
Materials Selection for Long Life in Low Earth Orbit: A Critical Evaluation of Atomic Oxygen Testing with Thermal Atom Systems
Authors: Koontz S. , Albyn K. , Leger L.
Published: November 2020

The use of thermal atom test methods as a materials selection and screening technique for low-earth orbit (LEO) spacecraft is critically evaluated. The chemistry and physics of thermal atom environments are compared with the LEO environment. The relative reactivities of a number of materials determined in thermal atom environments are compared with those observed in LEO and in high-quality LEO simulations. Reaction efficiencies (cm3 atom-1) measured in a new type of thermal atom apparatus are one-thousandth to one ten-thousandth those observed in LEO, and many materials showing nearly identical reactivities in LEO show relative reactivities differing by as much as a factor of eight in thermal atom systems. A simple phenomenological kinetic model for the reaction of oxygen atoms with organic materials can be used to explain the differences in reactivity in different environments. Certain specific thermal atom test environments can be used as reliable materials screening tools.
Air Toxic Risk Assessment
Authors: Gratt Lawrence
Published: November 2020

The release of toxins occurs from a multitude of sources both with and without air pollution control. These sources have become of more concern. The value of pollution control for toxicants can be addressed from a risk benefit methodology. The risks can be estimated from the Air Emission Risk Assessment Model (AERAM), a computerized methodology developed by EPRI for the electric utility industry, used to assess cost-benefit trade-offs for various control techologies. This methodology considers particle-size class emissions, dispersion, and health impacts, and has been used to evaluate trade-offs for fuel switching at a coal-fueled electric-power generating station in the Northeastern United States.
Selecting Nearly Optimal Sampling Locations Throughout an Area: Application to Cleanrooms and Federal Standard 209
Authors: Cooper Douglas , Grotzinger Stephen , Nackman Lee , Srinivasan Vijay
Published: November 2020

Various types of environmental assessment are done by taking an array of samples throughout an area. In sampling an area by taking point samples, the choice of sampling locations becomes important. It is assumed here that the task is to take no less than N* samples in a fairly uniform array throughout an area that is a fairly simple shape, such as a rectangle or a combination of a small number of rectangles. Different formulations of the problem are explored. Except in rare instances, a strictly optimum solution would be difficult to compute. "Nearly optimal" solutions to the problem have the minimum or nearly the minimum number of samples required and produce square or nearly square subregions associated with the samples. Approaches for obtaining sampling grids that are nearly optimal are discussed, and one example is presented in detail.
Air-to-Air Missile Airframe Captive Flight Vibro-Acoustic Environment
Authors: Poynor Stanley
Published: November 2020

Ground simulation and captive flight tests were conducted on an air-to-air missile airframe. Both internal carriage, at subsonic and transonic speeds (0.7 <M≪1.0), and conformal carriage, at supersonic speeds (M≪1.8), were tested for the missile/FB-111 combination. Twenty-three vibro-acoustic and 27 strain measurements were made at six locations on the test article. The tests were performed to demonstrate flight worthiness of the airframe technology and compatibility of the missile with the aircraft. Comparison of responses measured in flight with predicted captive environments showed close agreement.
Cleanroom Wipers: Particle Generation
Authors: Kong Kwok Wo , Summers James
Published: November 2020

Cleanroom wipers are essential in precision cleaning processes. Particles are to be removed by these wipers, and testing and quality control are extremely important. This presentation offers results obtained by various methods used to test particle generation from commercially available wipers. This study explores possible mechanisms of particle generation and attempts to identify a realistic testing method that simulates conditions of wiper use.
CFC Regulations on Refrigeration Compressors Used in Environmental Test Chambers
Authors: Hearn Brian
Published: November 2020

The earlier discovery of the Antarctic ozone "hole" and current scientific evidence indicate that CFC emissions into the atmosphere deplete the ozone layer and present a long-term threat to the quality of human life. The items of most concern, from an ozone protection standpoint, are the long-lived, fully halogenated compounds—halons, CFCs, and chlorocarbons. Scientific information indicates that most, if not all, of the chlorine or bromine content of these compounds is transported to the stratosphere, where it has the potential to destroy ozone. Furthermore, these compounds remain in the atmosphere for an extended number of years, providing a significant background chlorine concentration. According to DuPont.2 an 85 percent reduction in global CFC emissions from 1986 levels is necessary just to maintain current atmospheric levels of chlorine from these compounds. The refrigerants used within environmental test chambers have been included among those identified as ozone depleting. Specifically, these are CFC-12 and CFC-502.

The 1987 Montreal Protocol was revised in June of 1990. Further regulations on CFC products are contained within the Clean Air Bill that is being debated in the Fall of 1990. Restrictions pertaining to CFC-13 are being proposed.
Design Consideration of Expander Heads for Vibration Systems: Part I: Natural Frequency Equations for Square, Constant Thickness Expander Heads
Authors: Lipp Louie
Published: November 2020

Vibration testing, particularly when performed in reliability test chambers, is very costly. Design considerations for vibration expander heads that will accept several test specimens for simultaneous testing are discussed in this report. Well-designed expander heads will provide more meaningful results and reduce test time and costs through maximum utilization of test hardware.

This article, the first of a three-part series, discusses natural frequency equations for square, constant thickness expander heads. Parts II and III will cover damping equations for square, constant thickness expander heads and the inverted truncated pyramid expander head. Complete derivations accompany each expander head equation.
Development of a Reliability Test Profile for an ECM Pod Based on Measured Flight Conditions
Authors: Schmidt Robert
Published: November 2020

A test profile was developed to evaluate the reliability of an electronic countermeasures (ECM) pod. The profile combines air and liquid temperature cycling and various vibroacoustic levels to duplicate measured inflight thermal and vibratory response of the ALQ-184 ECM pod.

An ALQ-184 ECM pod was equipped with an environmental data collection system that included 25 thermal sensors, 18 vibration sensors, and a telemetry system to allow real-time monitoring of response levels during captive flight. The pod was flown on F-4, F-16, and A-10 aircraft at Eglin Air Force Base (AFB) under typical operation mission conditions.

Thermal and vibration response date were analyzed, and a reliability test profile was developed that simulates operational mission conditions for the F-4, F-16, and A-10 aircraft. The test profile is expressed in terms of pod response and is based on using temperature-conditioned air to provide the thermal response of printed wiring assemblies, temperature-conditioned liquid to provide the thermal response for coldplates, and 16 different vibroacoustic levels to provide the pod vibratory response. Each vibroacoustic level used the spectral data from five critical accelerometer locations on the pod structure to defin the required pod response.

The 6 hr reliability test profile simulates the thermal and vibratory response for 29 sequential flight conditions for the three aircraft. During the profile, the pod electrical status is cycled between standby, transmit, and off modes. The reliability test profile was used to perform reliability growth testing on early production pods and is being used for reliability qualification and production reliability acceptance testing during production.
The Delta Star Thermmal Vacuum Test: A Unique Approach to Space Thermal Simulation
Authors: Durant Dick , Fuld Christopher
Published: November 2020

Several techniques were developed to perform the thermal vacuum test of the Delta Star Spacecraft. Test design and fabrication was completed in only four months, producing a 21-zone, computer-modeled reflectorless lamp array system. Array zone control was based on discreet absorbed flux measurements provided by adiabatic coupons that were conceived to eliminate the need for conventional radiometers. Test requirements, methodology, anomalies, test data correlation, and flight data correlation are presented.
The Deposition of Contaminants from Deionized Water onto Hydrophobic Silicon Wafers
Authors: Riley Deborah , Carbonell Ruben
Published: November 2020

The liquid-based deposition of particles onto hydrophobic silicon surfaces was investigated by exposing hydrophobic silicon wafers to sample contaminants in a stirred deionized water bath. Wafers were rendered hydrophobic by exposure to dilute hydrofluoric acid, and a goniometer was employed to monitor wafer contact angles. As has been observed in the past for hydrophilic wafers, the zeta potential recorded for the test particle had a significant impact on the deposition resulting on the hydrophobic silicon surfaces. This suggests that, despite treatment with HF and an overall hydrophobic surface behavior, regions remain on the wafer surface which are ionizable in aqueous solutions.

The behavior of the silicon test wafers used in these studies is consistent with the presence of a negative zeta potential at the hydrophobic silicon surface. In contrast to the deposition seen on hydrophilic wafers, however, deposition onto hydrophobic silicon is frequently nonuniform.

Additionally, Auger analysis indicates that hydrophobic surfaces show a marked tendency to attract hydrocarbon contaminants from the deionized (DI) water. The rinsing technique employed when rendering wafers hydrophobic was found to have a significant effect on baseline particulate levels, and test results indicate that contamination differences between hydrophobic and hydrophilic wafers may be more strongly related to exposure to gas/liquid interfaces than to differences in the rates of particle deposition in bulk solution.
Tailoring Shipboard Environmental Specifications: Part I. Introduction, Temperature, Humidity, and Shock
Authors: Chalmers Richard
Published: November 2020

This article, the first of a three-part series, was extracted from Technical Document (TD 2071) published by the Naval Occan Systems Center in April 1991. Titled "Tailoring Shipboard Environmental Specifications, A Guide "for Navy Program Managers," the document presents a compilation of shipboard environmental data measured over the years. The applicability of the data to the fleet of today is discussed. Methods of tailoring systems specifications and tests for the environments existing at given locations on a variety of Naval ships are also discussed.

This article contains the Introduction, Temperature and Humidity, and Shock sections of TD 2071. Part II of this series will cover part of the TD 2071 treatment of Vibration, Part III will conclude Vibration and include Discussions and Conclusions. It also will present a tailored vibration requirement that a program manager might include in a procurement package for new shipboard systems.
Mechanisms of the HF/H2O Vapor Phase Etching of SiO2
Authors: Helms C. , Deal B.
Published: November 2020

In this paper we report on studies of the mechanisms responsible for HF/H2O etching and cleaning of Si surfaces. From these studies we have clearly established that the role of water is to provide a condensed solvent medium for the HF on the surface. Our results, as well as those in the literature, show that if the partial pressures of HF and H2O are too low (or sample temperature too high), condensation does not occur and little or no etching is observed. Based on these ideas, and pressure data from the literature, we have developed a detailed model that provides for the calculation of the onset of condensation as a function of wafer temperature and reactant partial pressures. In addition, the model allows determination of the HF concentration in the condensed H2O film. Comparison of etch rates obtained for aqueous etching as a function of HF concentration, and vapor phase etching as a function of calculated HF concentration, show good agreement. The vapor phase etch rate data, as a function of wafer temperature, total HF + H2O pressure, and partial pressure ratios, will be presented in detail along with information on the model.
Fractal-Based Characterization of Surface Texture
Authors: Grosser Ken , Chesters Stephen , Wang Hwa-Chi , Kasper Gerhard
Published: November 2020

The surface roughness of high purity gas system distribution materials is a matter of concern for many critical manufacturing processes. Control of this roughness is thus much in demand and requires a sensitive measurement method. A refined fractal-based characterization is presented as a possible solution. Test data that use this method to compare various surface finishes and correlate roughness with surface cleanability are offered with explanations. This could become an effective quality assurance tool in those applications where surface roughness is important.
Methodology of Developing a Combined Environmental Stress Schedule for Reliability Growth Testing: Part II. The Tracked Vehicle Vibration Environment
Authors: Lipp Louie
Published: November 2020

This three-part series describes how to develop an environmental test schedule for military ground-mobile equipment installed on a tracked vehicle based on the user's mission profile. The test schedules combine both operational and storage environmental stresses. Part I describes the equipment to be tested, provides a general overview of its mission profiles, and identifies appropriate climatic conditions. Part II discusses the complexities of the tracked-vehicle vibration environment, including research conducted in the Arizona desert and the Alaskan aretic. Part III compares test profiles based on excluding benign environmental phases with profiles that include benign stress conditions.
Tailoring Shipboard Environmental Specifications: Part III. Random Vibration
Authors: Chalmers Richard
Published: November 2020

This article, the third in a three-part series, is extracted from Technical Document (TD 2071) published by the Naval Ocean Systems Center in April, 1991. Titled "Tailoring Shipboard Environmental Specifications, A Guide for Navy Program Managers," the document presents a compilation of shipboard environmental data measured over the years. The applicability of the data to the fleet of today is discussed. Methods of tailoring systems specifications and tests for the environment existing at given locations on a variety of naval ships are also included.

The first article in the series (Journal of the IES, p. 25, March/April, 1992) included the Introduction, Temperature and Humidity, and Shock sections of TD 2071. The second article in the series (Journal of the IES, p. 27, May/June, 1992) covered the first part of the TD 2071 discussion of vibration. This article finishes the discussion of vibration and includes a "tailored" vibration requirement that a program manager might include in a procurement package for new shipboard systems.
Implementation of the TOMS Contamination Control Requirements in the Former USSR
Authors: Abrams Eve
Published: November 2020

The American Total Ozone Mapping Spectrometer (TOMS) was integrated with the Russian Meteor-3 spacecraft and launched on August 15, 1991. Although the TOMS instrument was sensitive to both particulate and molecular contamination, the program for Metcor-3 had not formerly addressed contamination control in ground operations. In order to accommodate the TOMS cleanliness requirements, a contamination control program was successfully established from inception at both the Meteor-3 spacecraft plant near Moscow and at the launch site in Plesetsk.
A Comparison of Manual and Automated Access to Microenvironments
Authors: Mitchell Kimberley , Briner Donald
Published: November 2020

Floor space in a Class 1 or better cleanroom costs approximately $2000 to $3000 per square foot to construct. Operating costs for these rooms are equally expensive. It is also true that even the best cleanroom facility may be subverted by sources of contamination within the cleanroom itself.

Due to these factors, many new semiconductor fabs are built with provisions to isolate wafer processing areas from the rest of the factory by means of various enclosures, which may be grouped into the category of wafer isolation technologies. These include cluster tools, clean-tool units mounted directly on equipment (microenvironments), and equipment surrounding clean air enclosures (minienvironments).

For each configuration, critical considerations include wafer transport and loading. Wafer transport mechanisms must keep wafers stringently clean and protect wafers from breakage. Typical methods of wafer cassette transport include standard mechanical interface (SMIF) pods, run boxes, and open cassettes.

This paper examines the relative cleanliness of various modes of accessing microenvironment enclosures at varying cleanliness levels of ambient air surrounding the microenvironment. Ambient air cleanliness tested ranges from Class 10 to Class 10,000.

Wafer cleanliness is measured through the use of a wafer surface scanner to measure particles per wafer pass (PWP). Access methods tested include a swinging door, SMIF robot arm, flexible curtain, and Manual Access Port (MAP). (Manual Access Port and MAP are registered trademarks of Briner/Yeaman Engineering, Inc.)
Temperature and Vibration Results from Captive-Store Flight Tests Provide a Reliability Improvement Tool
Authors: Calatayud Richard , Szymkowiak Edward
Published: November 2020

The ALQ-131 electronic countermeasure (ECM) system has provided the United States Air Force with proven self protection for many of its tactical fighter aircraft. The reliability and maintainability improvements of the ALQ-131 Block II has produced a system with a mean time between failures (MTBF) of 120 to 180 hours and greater than 95 percent availability for the 390 systems in theater during the Persian Gulf war. None of the aircraft carrying the ALQ-131 Block II was shot down, and at least 60 percent of the ALQ-131 Block IIs never needed maintenance and stayed on the aircraft throughout the air campaign. Due to classic reliability and maintainability approaches, the ALQ-131 has reached this high standard, but improved understanding of the environment experienced by the system will provide the next steps in reliability improvements. The capture of measured response data, as detailed in this paper, will provide a basis for developing life cycle and customer warranty tests which will guarantee to the customer that the ALQ-131 system will continue to perform reliably from takeoff to landing, and from mission to mission through the life of the system.
Methodology for Developing a Combined Environmental Stress Schedule for Reliability Growth Testing: Part III. Designing a Reliability Test Schedule with Combined Environmental Schedules
Authors: Lipp Louie
Published: November 2020

This article, the third of a three-part series, discusses how to develop an integrated environmental test schedule for military ground mobile equipment. Part 1 described the equipment to be tested, provided a general overview of mission profiles, and identified appropriate climatic conditions. Part II discussed the complexitics of the tracked-vchicle vibration environment, including research conducted in the Arizona desert and the Alaskan Arctic. Part III combines the information discussed in Parts I and II into combined environmental stress schedules. The first test schedule is "real-time" in that mean-time-between-failures (MTBF) could be approximated from the results, and the second test schedule attempts to find system weaknesses by deleting benign environments.
Optical System for Measurement of Pyrotechnic Test Accelerations
Authors: Lieberman Paul , Czajkowski John , Rchard John
Published: November 2020

This effort was directed at comparing the response of several different accelerometcr and amplifier combinations to the pyrotechnic pulse simulating the ordnance separation of stages of multistage missiles. These pyrotechnic events can contain peak accelerations in excess of 100,000 G and a frequency content exceeding 100,000 Hz. The main thrust of this work was to compare the several accelerometer systems with each other and with a very accurate laser Doppler displacement meter in order to establish the frequency bands and acceleration amplitudes where the accelerometer systems are in error. The comparisons were made in simple sinc-wave and low-acceleration amplitude environments, as well as in very severe pyroshock environments. An optical laser Doppler displacement meter (LDDM) was used to obtain the displacement velocity and acceleration histories, as well as the corresponding shock spectrum.
Environmental Engineering Within the Automotive Component Development Process
Authors: Aldridge Dustin
Published: November 2020

This paper discusses a test engineering philosophy and the development of knowledge-based tests for automotive components. To ensure success in the product delivery process, accurate measures of total product quality comprised of quality, reliability, durability, performance (QRDP) must be provided to the product development team. Accuracy in environmental testing for automotive components involves the integration of customer-usage, geographic, and application data into the test specifications. Discussion of the inputs required for knowledge-based tests are provided for the automotive vibration, thermal, corrosion, and dust environments.
Size Distributions of Particles Extracted from Disk Drive Parts: Comparison with the MIL-STD-1246 Distribution
Authors: Nagarajan R. , Welker R.
Published: November 2020

MIL-STD-1246B states that naturally occurring particulate contamination on surfaces follows a lognormal distribution with a geometric mean of 1 micron. Thus, when the logarithm of cumulative particle count is plotted against the square of the logarithm of particle size, an approximate straight line should result. However, deviations from this "natural" behavior have been observed in many manufacturing environments involving specialized machining or cleaning. Complex disk drive components, such as machined castings or ground surfaces, must be inspected by first extracting contaminants into a fluid by some means (e.g., ultrasonically, or with a pressurized spray), and then monitoring the particle population in the fluid. The cleaning method and the extraction method, in particular, can cause a significant departure from the lognormal approximation. The substrate material also influences the extent of this departure, as does its cleanliness level. These aspects are brought out by the plotting of actual particle size distributions obtained by extracting particles from substrates that are cleaned using a variety of methods. These are compared against the MIL-STD-1246 distribution. Conclusions are drawn regarding the effects of the cleaning process and the measurement procedure on the applicability of the MIL-STD distribution for various substrates. Implications of these conclusions for the derivation of particulate cleanliness specifications and for modifying MIL-STD-1246B are pointed out.
Reliability Testing of Semiconductor Devices in a Humid Environment
Authors: Bâzu Marius , Tazlauanu Mihai
Published: November 2020

The influence of humidity on semiconductor device reliability is investigated with two main purposes: to emphasize the role of humidity in the failure process as a stress factor and to model the reliability-humidity relationship. Experiments were performed on two types of plastic encapsulated semiconductor devices (optoelectronic and ICs). Reliability data obtained from functioning at humidity and temperature are compared with those obtained from functioning at the same temperature but at a lower humidity level. The role of humidity as a stress factor becomes obvious when the specific failure mechanisms induced are identified. The experimental data are also used to validate an original model, a generalized Arrhenius relation. The model allows the design of accelerated tests with humidity as one of the stress factors. The model is compared with previous models.
Recovery and Recycle of HCFCs by Activated Carbon Adsorption
Authors: Logsdon P. , Basu R.
Published: November 2020

Various chemicals, such as chlorofluorocarbons (CFCs) methyl chloroform, carbon tetrachloride, and halons will be phased out globally by 1995 because of their potential contribution to stratospheric ozone depletion. Hydrochloroflurocarbons (HCFCs) are considered as replacements for the CFCs in certain applications (e.g., solvents and foam expansion agents). In a number of applications, CFCs are recovered using adsorption on activated carbon and reused. In this paper, we have described how to use activated carbon to adsorb 1,1-dichloro-1-fluoroethane (HCFC-141b) from an airstream and later recover and recycle using steam desorption. The capacity of commercially available carbons to adsorb HCFC-141b and conditions to be used in the process are described.
Summary of Cassini Acoustic Criteria Development Using Titan IV Flight Data
Authors: Himelblau H. , Kern D. , Davis G.
Published: November 2020

The Cassini spacecraft is being developed by the Jet Propulsion Laboratory (JPL) for the National Aeronautics and Space Administration (NASA) to orbit and explore the planet Saturn, its rings, and satellites. Cassini will be launched on a Titan IV and boosted out of Earth orbit by a Centaur. This paper discusses the development of Cassini acoustic criteria using Titan IV flight data. Factors affecting the development of Cassini acoustic criteria using corrected Titan IV flight data1 include the statistical methods used to account for spatial and flight-to-flight variations, the use of maximax spectra, data corrections for acoustic pressure increases near the payload fairing surfaces, and corrections for payload fill factor effects. Separate acoustic criteria were developed for the two launch sites.
Improvements in Avionics-Durability Analyses
Authors: Followell David , Fields Scott , Liguore Salvatore , Perez Rigoberto
Published: November 2020

Predicting the reliability of electronics is as much of an art as an exact science. There are too many factors, both controllable and uncontrollable, which can not be readily identified, quantified, or combined into an all-inclusive and deterministic equation. However, progress has been made to simplify the prediction process. McDonnell Aircraft Company (MCAIR) has developed a software tool (E-Life) which will predict the fatigue life of solder joints, component leads, and plates through holes. E-Life is also capable of identifying the critical components that require analysis, greatly simplifying life predictions. The results of complex finite element analyses of printed circuit assemblies (PCA) are an integral part of the software, but are transparent to the user. Thus, the time to perform an analysis is reduced and the probability of error is decreased.

Experimental tests have been used to improve the accuracy of E-Life. Thermal, mechanical, and dynamic test results were used to obtain material properties previously unavailable. Test results were also used to validate the analytical models. When combined, E-Life and existing prediction techniques provide a more comprehensive reliability prediction process than was available in the past.
Accelerated Reliability Growth Models
Authors: Feinberg Alec
Published: November 2020

Extending reliability growth so that it can be applied in the area of accelerated testing will enable one to apply all the reliability growth tools and their planning advantages. This paper describes linking these two areas together into what is termed accelerated reliability growth testing (ARGT). Mathematical equations of ARGT for both iso-stress and step-stress accelerated testing are modelled.
Use of Residual Gas Analysis in Low-Pressure Semiconductor Process Reactors
Authors: Reath Mark , Brannen James , Bakeman Paul , Lebel Richard
Published: November 2020

Residual gas analysis (RGA) was used for troubleshooting tetra (ethoxyorthosilicate) (TEOS) and tungsten silicide chemical vapor deposition processes. In each process, RGA identified reactor impurity sources later proven to be the root cause of film defects and foreign material deposition. RGA verified the effectiveness of modified reactor hardware and operating procedures. This paper describes two case studies that represent RGA contributions to the 0.5-μ process development at the IBM semiconductor manufacturing facility in Essex Junction, Vermont.