Commercial Off-the-shelf Parts Research Articles

Method and software platform for electronic COTS parts reliability estimation in space applications

Adoption of electronic Commercial-Off-The-Shelf (COTS) parts in various industrial products is rapidly increasing due to the accessibility and appealing lower cost of these commodities. Depending on the type of application, having an accurate understanding of the COTS failure information can be crucial to ensure the reliability and safety of the final products. On the other hand, frequent large-scale testing is often cost prohibitive and time consuming for emerging technologies, especially in the consumer electronics sector where minimizing time-to-market and cost is critical. This paper presents a comprehensive Bayesian approach and software platform (named COTS Reliability Expert System), that integrates multiple pieces of heterogeneous information about the failure rate of COTS parts. The ultimate goal is to reduce dependency on testing for reliability analysis and yet to obtain a more accurate “order of magnitude” estimate of the failure rate through an efficient process. The method provides a foundation for incorporating manufacturers reliability data, estimates based on underlying physics-of-failure mechanisms and circuit simulations, partially relevant life test data of similar (but not necessarily identical) parts, and expert opinions on the manufacturing process of the COTS part of interest. The developed expert system uses Bayesian estimation to integrate all these types of evidence. The methodology is demonstrated in estimating the failure rate of a static random-access memory (SRAM) part.

Reliable flight computer for sounding rocket with dual redundancy: design and implementation based on COTS parts

Sounding rockets provide a useful platform for the aerospace research activities. One of the main and substantial parts of the sounding rockets is the flight computer which is responsible for the management of the other subsystems, running the flight scenario, and data acquisition from the experimental payload. Due to the crucial role of the flight computer in the success of the devoted mission, high reliability is one of the main requirements of the flight computer. Technical, systematical, and operational requirements alongside the procurement problems of the special-purpose space-grade components, force this research to take a dual redundant architecture based on the commercial off-the-shelf (COTS) components. Although the theoretical aspect of the reliable flight computer has been investigated extensively, design and implementation of a dual-redundant reliable flight computer are presented in this paper, which has very rarely been published. The processing unit, data bus unit, and the sensors/actuators are designed to be dual redundant. The supervisor monitors the operational units and if it detects any failures, replaces them with the spare ones while trying to make the repair through restarting. If it succeeds in recovering the failed unit, the system continues its operation as a dual-redundant system; otherwise, it becomes a single system. Our analytical assessments show that the reliability of a dual-redundant computer with the COTS components is comparable with the reliability of a single computer being composed of the special purpose components with tens of times lower failure rates. The evaluations show that the reliability requirement of the system is covered while saving the cost considerably.

The Reliability Impact of Reballing COTS Pb-Free BGAs to Sn/Pb for Military Applications

The electronics assembly market has experienced a material shift from lead (Pb) based solders to Pb-free solders. This is a result of the widespread adoption of Reduction of Hazardous Substances (RoHS) legislation and practices in commercial industry. As a result, it is becoming increasingly difficult to procure commercial off-the-shelf (COTS) components with tin-lead (SnPb) solder balls or finish. There are essentially three responses to the scarcity of acceptable SnPb parts: custom order, post process or adapt. Custom ordering parts with SnPb finishes negates the benefits of COTS based acquisition; however, has a reduced reliability risk because the material and processes are known. Reprocessing parts once in house saves money because the parts are COTS, but expends money and resources by performing post processing on them. Also, the additional touch labor and handling increases the risk of damaging the part. Finally, adapting to Pb-free finishes is the preferred long term approach because it preserves the cost benefits of using COTS parts and does not require post processing. It is the riskiest approach due to the lack of historical data in the DoD environment. This paper presents results regarding reballing 208 I/O Ball Grid Array (BGA) parts from tin-silver-copper (SAC305) solder to SnPb eutectic solder. It is important to understand the reliability risks associated with the reballing procedure, particularly as it relates to thermal cycling, shock and vibration environments. Three major efforts will be presented to answer these concerns. First, a survey of reballing vendors was performed to better understand the processes and variables associated with that industry. The results of that survey were used to down-select to five vendors that were used for the physical testing portion of the effort. Finally, physical testing consisting of thermal cycling, shock, and vibration was performed. The physical testing was performed on parts from the five different reballing vendors as well as native SnPb parts and native SAC305 parts. The results of these activities will be presented.

Spacecraft Attitude and Body Rate Estimation with Four Star Sensor Heads: Concepts and Ground and On-Orbit Verification Results

AbstractWe have developed a star sensor system with four heads as a prototype of a future small and low-priced satellite attitude controller. To reduce size and cost of the controller, we integrate attitude sensors into star sensors with medium resolution and medium sensitivity and adopt Commercial Off-The-Shelf (COTS) electrical parts for key parts such as CPU and CCD. Newly developed computer architecture is introduced for high reliability with COTS parts under the harsh space environment. In this paper, we will focus on the new star identification algorithm dedicated for the proposed four-head star sensor system and evaluate it with ground test and on-orbit check-out data.

OWLS: a ten-year history in optical wireless links for intra-satellite communications

The application of Optical Wireless Links to intra- Spacecraft communications (OWLS) is presented here. This work summarizes ten years of developments, ranging from basic optoelectronic parts and front-end electronics, to different inorbit demonstrations. Several wireless applications were carried out in representative environments at ground level, and on in-flight experiments. A completely wireless satellite will be launched at the beginning of 2010. The benefits of replacing standard data wires and connectors with wireless systems are: mass reduction, flexibility, and simplification of the Assembly, Integration and Tests phases (AIT). However, the Aerospace and Defense fields need high reliability solutions. The use of COTS (Commercial-Off-The- Shelf) parts in these fields require extensive analyses in order to attain full product assurance. The current commercial optical wireless technology needs a deep transformation in order to be fully applicable in the aforementioned fields. Finally, major breakthroughs for the implementation of optical wireless links in Space will not be possible until dedicated circuits such as mixed analog/digital ASICs are developed. Once these products become available, it will also be possible to extend optical wireless links to other applications, such as Unmanned Air and Underwater Vehicles (UAV and UUV). The steps taken by INTA to introduce Optical Wireless Links in the Space environment are presented in this paper.

スターセンサを用いた衛星姿勢および角速度の推定とその軌道上実証

We have developed Satellite controller Integrated with Star sensors (SIS) as a prototype of a future small and low-priced satellite controller. To reduce size and cost of the controller, SIS integrates attitude sensors into star sensors with medium resolution and medium sensitivity, adopts Commercial Off-The-Shelf (COTS) electrical parts for key parts such as CPU and CCD, and integrates several electronics for star identification, attitude determination, attitude control, and data handling into a single processing unit. Newly developed computer architecture is introduced for high reliability with COTS parts under the harsh space environment. In this paper, we will focus on the new star identification algorithm dedicated for star sensors with medium resolution and medium sensitivity and evaluate it with in-orbit experiment data of SIS.

Suitability analysis of commercial off-the-shelf components for space application

With the rapid development of microelectronics technology and the increasing requirement of high performance in space missions, existing space-level radiation-hardened components and technology cannot meet the design of high-performance spacecraft. More and more commercial off-the-shelf (COTS) components are widely used in some space missions to achieve high performance. However, COTS components are designed working in terrestrial operating conditions, and the electronic components used in spacecraft usually have a much higher reliability and suitability requirement because of the nature of space missions. Therefore, the successful use of COTS components in space applications is closely related to reliability and suitability issues, which have to be considered before using COTS parts in the harsh environment in space. This article summarizes the state-of-the-art COTS components suitable for space applications, discusses the problems and risks of using COTS components in space, and presents a suitability analysis approach for COTS components in Chinese space projects. The approach consists of analysis, tests, and evaluation of thermal environment, vibration and shock environment, radiation environment, and vacuum environment. In order to illustrate the usage of the approach, two examples have been selected as case studies. One is the Chinese SZ-4 spaceship with a COTS part AD595 and the other is a joint space project between the Europe Space Agency and the Chinese National Space Administration, which is called the Double-Star Project, with a COTS part MAX471.

우주방사능 효과를 고려한 저가 COTS 소형위성의 신뢰성 분석

The reliability and failure mode effect analysis are effective means to achieve efficient and cost-reduction design for satellite development. The failure rate of COTS (Commercial-Off-The-Shelf) parts required for reliability analysis is not usually provided from the manufacturer. Space environment factors based on empirical data obtained from MIL-HDBK-217F can be applicable to the reliability calculation. As a radiation environment factor, the occurrence rate of SEL (Single Event Latch-up) is additionally incorporated for the failure rate prediction. In this paper, the statistical reliability analysis method for low-cost small satellite using COTS parts is suggested. This statistical reliability analysis was applied to HAUSAT-2 small satellite whose electronic boxes are consisted of many COTS parts to calculate the system reliability at the end of design mission life.