Passive Component Failures

The only SM components with obvious fatigue failures after more than 6700 cycles of 0-100°C, or 5000 cycles of —55 to + 125°C were LCCCs and 1206 chip resistors. No leaded SM devices exhibited failures. There were no unexpectedly early or catastrophic chip carrier or passive component failures. Those failures that occurred followed the same component order as observed for eutectic Sn-Pb. The ranking of alloys relative to eutectic Sn-Pb varied with thermal cycle and component type. Each solder alloy is able to withstand different amounts, types, and rates of loading, which are dependent upon the different coefficients of thermal expansion (CTE) and mechanical properties of the board, components, and alloys, and upon solder joint configurations. 

This ordering by singles, doubles and triples takes added meaning when the failure rates of the active and passive components (Table 1.4.3-1) are included. A doublet has a failure frequency that is the product of the two failure rates a triplet is the product of three... 

The model outlined is particularly suited for treating the failure of passive components. Such components fiilfil their function by their mere presence, for example vessels, pipes and walls. Contrary to this active components have to move in order to fulfil their function. Examples are control valves and pumps. Yet, active components usually have a passive ancillary function. Thus, the pump casing serves as well to contain the transported medium. 

Depending on whether we deal with a risk-based or a detailed risk study the scope of the failure mechanisms represented by the failure rates must differ. For risk-based analyses the failure rates should represent besides spontaneous failure failures caused by impermissible loads on structural materials following malfunctions or operator errors. Since the latter are explicitly modelled in a detailed risk analysis the failure rates for passive components used there should only represent the spontaneous part. The scope of the failure mechanisms covered is usually not described in suflhcient detail and can practically not be determined a posteriori [5]. 

A single failure of any active component (assuming passive components function properly) nor... 

A single failure of a passive component (assuming active components function properly). 

Single failures of passive components in electric systems should be assumed in designing against a single failure, A single failure of a passive component in other systems and structures should be considered as required,... 

A single failure of a passive component (assuming active components function properly), results in a loss of the capability of the system to perform its safety functions. 

In the single failure analysis, the failure may not need to be assumed of a passive component designed, manufactured, installed, inspected and maintained in service to a high quality level. However, when it is assumed that a passive component does not fail, such an approach shall be justified, taking into account the total period of time that the component is required after the initiating event. 

Consideration of the need to design against single failures of passive components in fluid systems important to safety. (See Definition of Single Failure.)... 

SCB The SCB is a passive confinement, fabricated principally of stainless steel. Sealed glass windows and other sealed penetrations exist as part of the SCB boundary. A failure rate of 0.001 is assumed for this passive component. Since the operator continually monitors the SCB pressure differential, this may be a conservative estimate, i.e. suspect SCBs would be taken out of service. (Mahn et al. 1995, Table 5)... 

Reliability of electronic devices is caused predominantly by failures which result from the latent defects created during the manufacture processes or during the operating life of the devices. A search for new nondestructive methods to characterise quality and predict reliability of vast ensembles became a trend in the last four decades (Saveli etal. 1984), (Hartler et al. 1992), (Vandamme 1994), (Hashiguchi et al. 1998). The most promising methods to provide a non-destructive evaluation are an analysis of the electron transport parameters. Experiments are based on the measurements of device VA characteristics, nonlinearity using the non-linearity index (NLl), electronic noise spectroscopy, electro-ultrasonic spectroscopy and acoustic emission. These ones apply to both active and passive components, i.e., bipolar devices and MOS structures, on one hand, and resistors and capacitors on the other. 

Passive barriers (such as heat exchanger tubes). For heat exchanger tubes with the possibility of experiencing shock loads under accident conditions or when tube failures are assumed as the single failure of a passive component, the adequacy of these tubes as the sole barrier should be determined and additional measures should be taken if necessary. 

A biologic surface that develops an endothelial cell surface is referred to as a neointima. If it is covered with blood components such as fibrin, it is called a pseudointima. In both cases, the surfaces are passive with respect to the blood to which they come into contact. A pseudointima, however, is typically unstable and subject to further ihrombic response. If the surface is damaged, as during surgical implantation, a catastrophic failure can result. This coupled with the difficulty of developing a complete endothelial layer caused one researcher to describe a device as physiologically tolerable rather than biocompatible or hemocompatible. 

The commonest cause of impredicted corrosion problems is the failure to define, accurately, the chemistry of process streams, including startup, shutdown, and transient conditions, or to anticipate changes in chemistry at specific locations in equipment. The corrosivity of a process stream is often determined by its minor components, e.g., the presence of lOs-lOOsppm chlorides can promote localized corrosion of stainless steels and other passive alloys. It is important that minor components are defined, quantified, and evaluated at the design stage, including their possible local concentration such as in distillation and separation equipment. 

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