Use of high temperature operating life data to mitigate risks in long-duration space applications that deploy commercial-grade plastic encapsulated semiconductor devices
Abstract Commercial-grade plastic encapsulated semiconductor devices are now widely used in space and military equipment for their cost-per-performance and availability advantages over military type ceramic parts. However, many equipment manufacturers still perceive risks in their deployment, and conduct expensive and time-consuming screening and qualification programs to mitigate the potential risks associated with their use. This paper discusses the limitations of the screening and qualification approach currently employed by space equipment manufacturers to assess the long-term reliability of commercially-available plastic encapsulated semiconductor devices (PEDs) in deep space missions. In addition, the paper presents the value of the high temperature operating life (HTOL) data published by manufacturers of PEDs for mitigating the risks associated with the use of such devices in long-duration space applications, where steady-state temperature is the significant stress parameter.
Reliability assessment of electronic components exposed to long-term non-operating conditions
The decreased availability of MIL-SPEC components is forcing designers of low volume complex electronic systems, such as avionics and defense electronics, to consider the use of commercial off-the-shelf plastic encapsulated microcircuits (COTS PEMs). Traditionally, designers of these long-life, high reliability systems have been reluctant to use COTS PEMs because of concerns related to their capability to survive in harsh environments over long periods of continuous or intermittent operation. Many commercial insertion studies in the last several years have now conclusively demonstrated that PEMs made using best commercial materials, processes, and quality techniques will permit devices to perform reliably in the most severe environments. However, only recently have studies focused on the reliability of PEMs in that subset of applications requiring short time operation after long periods of unpowered storage (10 to 20 yrs). This paper presents the results of five critical commercial insertion studies focusing on long term storage reliability. These studies include analysis of PEMs, hermetic microcircuits, and assemblies stored for up to 28 yrs in various storage locations around the world. Regardless of the storage conditions, commercial grade PEMs, without screening or incoming inspection, survived assembly and extended storage, even though, in some cases, degradation was observed on the boards.
A new approach to reliability of commercial and military aerospace products: Beyond military quality/reliability standards
Recent changes in the commercial and military aerospace industries have caused us to question the traditional ways of measuring, predicting and assuring product reliability. These industries have been unique in that both quality and reliability have been almost completely controlled by government standards, a condition that will not survive the current upheaval in these markets. Traditional reliability prediction methods for military and commercial aerospace products use a probabilistic approach, such as that of MIL-HDBK-217, and Reliability Assurance relies on fixed quality levels in design and manufacture. These approaches almost uniformly assume that predicted equipment reliability is the sum of the predicted reliabilities of the electronic and electromechanical parts in the equipment and that once designed, reliability is a fixed attribute of the hardware. This paper describes a comprehensive approach to avionics reliability assurance which addresses all potential causes of unreliability. It is applicable to both commercial and military products. The approaches described here may be viewed as the next logical step beyond the traditional approach to quality and reliability found in current Military Standards. 
 
 
 
This paper is a call to change the way we think about reliability assurance in the military and aerospace markets. Six new approaches are suggested: (1) Adopt a continuous improvement, zero-defects mentality in the design of military and aerospace products; (2) develop a design-to-world-class cost and schedule mentality; (3) adapt world-class process control methods to low-volume, high-reliability manufacturing; (4) accept ownership for quality and reliability of all components and materials; (5) adapt world-class design practices to military and aerospace products; and (6) recognize that quality and reliability of parts, materials, and systems are the responsibility of those who manufacture them. 
 
 
 
Although ELDEC Corporation is installing a system with the above features, the implementation of these approaches will be unique to each user. The system described in this paper involves the use of many currently popular TQM methods, such as statistical process control, design of experiments and concurrent engineering. It also involves interaction of many functions within the manufacturing organization, as well as with suppliers and customers. Our listing of methods is not intended to be comprehensive, just illustrative.