Harsh environment electronics

The main factor that distinguishes harsh environment electronics from commercial electronics is the environment in which they perform. Harsh-environment microelectronics operate at temperatures well above the traditional maximum allowable operating temperatures of 70°C for consumer electronics, as in Table 1. 

Overview of thermal management for harsh environment electronics... 

The authors qualitative ranking of the potential applicability of various thermal management technologies for harsh environment electronics is shown in Figure 14. The potential applicability of these techniques in terms of criteria such as cost, ease of use, thermal performance, and reliability is compared. 

Future thermal management technology for harsh environment electronics will be focused on the following areas. 

Different types of SiC Field Effect Transistors, Metal Oxide Semiconductor Transistors (MOSFETs), Metal Semiconductor Field Effect Transistors (MESFETs), and Junction Field Effect Transistors (JFETs) compete for future applications in high temperature and harsh environment electronics. This Datareview details these various types of FETs, the structures used and the performances obtained. Interesting recent developments and potential applications, such as FET integrated circuits, a hybrid operational amplifier and an inverter circuit are also outlined. 

Sohd tantalum capacitors have a high volumetric capacitance which makes them attractive for use in miniaturized electronic systems like cellular telephones, hand-held video cameras, and personal computers. The insensitivity of their capacitance to temperature and their abiUty to operate at temperature extremes explains why these devices are used in such harsh environments as automobile engine compartments. Sohd tantalum capacitors are extremely rehable and, therefore, are often the capacitor of choice in critical appHcations like spacecraft electronics, pacemakers, and safety equipment. 

Following its rapid rise to dominance in the consumer cell market intended for portable electronics, lithium ion technology was actively considered for special applications such as those in military and space missions. However, the poor performance of the state-of-the-art lithium ion cells at temperatures below —20 °C remained a major obstacle to enabling the normal operations in harsh environments that are frequently encountered in those missions. For example, according to a comprehensive... 

Passive cooling is prevailing in current harsh-environment application because it is simple and reliable. However, as discussed in next section, passive cooling may not be sufficient to satisfy future generation high flux electronic cooling. 

Werner, M.R. Fahmer, W.R., 2001, Review on Materials, Microsensors, Systems and Devices for High-temperature and Harsh-environment Applications, IEEE Transactions on Industrial Electronics, Vol. 48, No.2, pp.249-257... 

On the other hand, chemical electronics (chemical sensing chip) production was probably less than 10,000 yearly (10 4 per capita) with a cost of 5 per chip. The yield is no better than 60 percent, and the metalization is platinum or gold. The feature size in the XY direction is typically on the micron scale, but it is 100 microns in the Z direction. The top layer is very high quality defect-free silicone nitrate, which is much higher quality than silicone dioxide. The lack of defects, as well as the gold or platinum metalization, allows the chemical electronics chip to function in harsh environments. 

The most widespread polymer currently in use for high-speed dynamic sealing applications in automotives is polyetheretherketone. These thermoplastic aromatic polymers are used in the aerospace, electronics, and nuclear industries [9], These materials have excellent mechanical- and chemical-resistance properties, which permit polyethere-therketones to be used in many engineering applications—often in harsh environments [10], These polyetheretherketones are the product of the reaction of 1,4-dihydroxyben-zene and 4,4 -di II non then /ophenonc [8]. Figure 6.5 shows this reaction. 

In modem cars, microsensors play an essential and increasingly important role as the interface between the vehicle, with its complex functions of motor management, chassis systems, safety, as well as comfort and convenience on the one hand, and the respective electronic control units on the other hand. Microsensors need to function in a harsh environment over the entire lifetime of an automobile. Therefore reliability aspects have come more and more into the focus of engineering and research activities in microsystem technology. 

It has already been mentioned that this band gap predestines SiC for electronic devices at high temperatures, but also for high power and high frequency operations and devices operating in harsh environments [197]. Therefore, it may be of interest to tailor this band gap for special applications. That is feasible by the formation of so-called superlattices, i.e., by forming exactly defined sequences of monolayers of different polytypes. 

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