Housing of electronics

In view of its application in the field of electronics there is particular interest in the coating of polypropylene mouldings against radio-frequency and electromagnetic interference the successful development of aqueous processes for polycarbonate provides a viable alternative to other methods for shielding the housings of electronic products—such as by paints containing nickel. 

FRs are chemicals that can inhibit ignition and/or reduce the burning rate of a product. These are often used by manufacturers to help them meet fire safety standards set down by law for products such as electrical equipment, furnishings, and vehicles. These compounds are added to polymers, paint, textiles, and other materials to improve their fireproof properties. The main applications are in plastic housings of electronic products such as TV sets and computers, car parts, circuit boards, electric components, and cables. There are currently over 100 different substances used as FRs and these can be classihed in four categories (Figure 31.1) ... 

The electrically conductive polymers have their greatest use in EMI-shielded casings and protective housings of electronic and telecommunications equipment, where they have rapidly substituted metal because of their low weight and easy workability. Steel fiber is mostly used in filled conductive polymers intended for EMI-shielding applications, which will be discussed below. 

Fesit Science Product Design Technology Center. Theory of neural networks and Matlab7 application. Beijing Publishing House of Electronics Industry, 2005. 

Antimony is used a synergist for flame retardants in circuit boards and plastic housings of electronics, but little is known about exposure in consumers or electronic waste workers. 

Antimony has been detected in electronic waste (e-waste) from different uses. This includes use in semi-conductor components as a flame retardant, or as a synergist with other flame retardants in circuit boards (Bi et al. 2011 Lincoln et al. 2007), and in plastic housings of electronic equipment (Santos et al. 2010). Antimony trioxide is used as a flame retardant in hard polymer plastics including acrylonitrile-butadiene-styrene plastic (ABS) commonly used for TV and computer housings (Tostar et al. 2013). Waste electric and electronic equipment (WEEE) exposure to antimony is of concern in Asia where most of the global WEEE is recycled, land-fiUed, or incinerated (Santos et al. 2010). 

Fig. 3. Replica electron micrograph showing "house-of-cards" microstmcture in a machinable fluormica glass-ceramic (white bar = 10 fiva).

Electronic-Grade MMCs. Metal-matrix composites can be tailored to have optimal thermal and physical properties to meet requirements of electronic packaging systems, eg, cotes, substrates, carriers, and housings. A controUed thermal expansion space tmss, ie, one having a high precision dimensional tolerance in space environment, was developed from a carbon fiber (pitch-based)/Al composite. Continuous boron fiber-reinforced aluminum composites made by diffusion bonding have been used as heat sinks in chip carrier multilayer boards. 

The main reasons for this lie in feasibility. Conducting fillers are rather expensive and their use increases the cost of an article. Besides, filled polymers have worse physical-mechanical properties, especially impact strength and flexural modulus. The use of fillers is also detrimental to the articles appearance and calls for additional treatment. The continuous development of electronics has also contributed to a loss of interest to conducting composites as screening materials the improvement of components and circuits of devices made it possible to reduce currents consumed and, thereby, noise level a so called can method is practised on a wide scale in order to cover the most sensitive or noisy sections of a circuit with metal housings [14]. 

GAO (2008) Report to the Chairman, Committee on Foreign Affairs, House of Representatives. ELECTRONIC WASTE EPA Needs to Better Control Harmful U.S. Exports through Stronger Enforcement and More Comprehensive Regulation. United States Government Accountability Office, Washington, DC... 

In the production mode the rotation rate of the P-CAC can be varied between 0°/h and 5000°/h. By comparison, the drivers used in the CAC units throughout the ORNL studies were only able to rotate the column between 2°/h and 1000°/h. The housing of the drive is made of stainless steel coated with polyethylene and protects the drive as well as the electronic parts against environmental influences. 

Structural foams are made of a cellular core with a dense skin. The technique is used for industrial and aesthetic goods for the automotive, electronics, household appliance and aeronautics sectors, such as housings of machines, TV cabinets, computer housings, roofs for caravans or ships, hard tops of 4WD (Jeep), luggage boxes, parts for washing machines. Structural foams are processed by thermoplastic injection moulding using ... 

For components or devices supplied hy outside manufacturers, usually the downward progression is stopped at the component level, unless the device is normally opened, repaired, calibrated, adjusted, or inspected hy in-house personnel. Electronic hlack boxes (similar to those under the hood of our automobiles) are good examples. We as owners may have occasion to manipulate the connection points (wires, attachment, and securing brackets), but we do not open nor usually attempt to diagnose an internal malfunction of these devices. For work on our automobile electronics black boxes, we turn to specially trained experts who use special equipment. 

William T. Coffey, Department of Electronic and Electrical Engineering, Printing House, Trinity College, Dublin, Ireland... 

Hren B. Ralph, in Third European Reg. Conf. Electron Microscopy, Prague, 1964,191, Publishing House of Czech. Acad. Sci. S. Ranganathan, ibid., 265. 

---