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Guidelines for Temperature-Tolerant Design and use of Microelectronic Devices
Published in Pradeep Lall, Michael G. Pecht, Edward B. Hakim, Influence of Tempemture on Microelectronics and System Reliability, 2020
Pradeep Lall, Michael G. Pecht, Edward B. Hakim
Derating is a technique through which either the stresses acting on a part are reduced, or the strength of the part is increased, in correspondence with allocated or rated strength-stress factors. When the equipment designer decides to select an alternative component with higher rated junction temperature or make a design change that maintains the temperature, consistently below the rated level, the component is said to have been derated for thermal stress. Thermal derating is one of the most common derating methodologies. The reliability of electronic systems is believed to be very sensitive to component derating and exactly how the derating is applied. Guidelines for derating of devices have emphasized lowering the steady state operating temperature [Brummet, 1982; Eskin, 1984; Naval Air Systems Command AS-4613, 1976; Westinghouse, 1986]. Some examples are presented in Table 1.
Hardware Development Methods and Tools
Published in Paul H. King, Richard C. Fries, Arthur T. Johnson, Design of Biomedical Devices and Systems, 2018
Paul H. King, Richard C. Fries, Arthur T. Johnson
Derating is the practice of limiting the stresses, which may be applied to a component, to levels below the specified maximum. Derating enhances reliability by Reducing the likelihood that marginal components will fail during the life of the system.Reducing the effects of parameter variations.Reducing the long-term drift in parameter values.Providing allowance for uncertainty in stress calculations.Providing some protection against transient stresses, such as voltage spikes.
Electronic Hardware Reliability
Published in Jerry C. Whitaker, Electronic Systems Maintenance Handbook, 2017
Michael Pecht, Iuliana Bordelon
Derating is a technique by which either the operational stresses acting on a device or structure are reduced relative to rated strength or the strength is increased relative to allocated operating stress levels. Reducing the stress is achieved by specifying upper limits on the operating loads below the rated capacity of the hardware. For example, manufacturers of electronic hardware often specify limits for supply voltage, output current, power dissipation, junction temperature, and frequency. The equipment designer may decide to select an alternative component or make a design change that ensures that the operational condition for a particular parameter, such as temperature, is always below the rated level. The component is then said to have been derated for thermal stress.
Assurance of electronic parts for aerospace system reliability: Past, present, and future
Published in Quality Engineering, 2021
Derating is when a component is designed to operate at limits that are below the normal limits for that component. Typically, derating reduces the degradation rate of the component. The role of derating to reliability is illustrated in Figure 2. Passive parts such as capacitors can especially benefit from derating. We can illustrate how derating can affect reliability based on testing performed with tantalum capacitors. While it is a bit of a misnomer to define a “rating” for Tantalum capacitors that are installed in a reverse configuration, it is useful in a situation in which the capacitors are installed and being used operationally and where they would be extremely costly and risky to replace. In this case, the capacitors are installed in ExPRESS Logistics Carriers on the International Space Station, in reverse polarity due to the use of an old drawing without polarity markings (Leitner et al. 2018). Here we consider a 25volt (V) rated tantalum capacitor operated at −5.1 V. Then we assess the temperature effect on one of the most common failure modes – a shorting condition indicated by increasing leakage current. While it is beyond the scope of this paper to discuss the full range of experiments, suffice it to say that at this voltage level, most such caps would fail within hours or days, but when operating in vacuum or otherwise without the presence of even traces of moisture, the caps behave nominally except with an elevated, but stable, leakage current on the order of mA, within a reasonable temperature range. We can monitor the stability of the leakage currents to determine whether the parts are on a path to failure or continue on for the foreseeable future.