The Electrical and Electronics Industry

This facet of industry might appear to be free from corrosion. On the contrary, there are problems such as the corrosion of aluminum used for tracks on most devices. There is the high probability of strong galvanic interaction with gold used for connectors. Many critical systems must function in severe environments such as a temperature range below zero to 40 °C, 100% humidity, airborne particulate matter and insects. This is certainly a challenging problem. 

About 75 years ago, the main material for cable sheathing was lead, protected from corrosion by asphalt-impregnated jute coating. Even then corrosion problems prevailed. Later on, extruded or drawn aluminum sheaths were in use, soon to compete with polythene. A large number of failures in the 1960s caused by water in the cable led to the development of sophisticated methods of sheathing involving coated aluminum and clad metals of copper adjacent to a number of steels (45). 

In spite of many advances made in materials (47) and coatings technology, civilian merchant fleets have suffered badly from poor maintenance by owners leading to major disasters, most of which is attributable to corrosion and poor maintenance at every level. The loss of the 170,000 ton Derbyshire in 1980 with all 44 crew members is speculated to be because of poor design, accentuated by corrosion. 

In the 1990-1991 time span, more than 30 bulk carriers were lost or damaged and more than 300 crew members died. A surveyor found corrosion from original 12 mm thickness down to 3-5 mm of steel during 10-15 years of life. For a long time, the owners cut their ship maintenance costs, which led to extensive corrosion and loss of lives. 

In 1993, the oil tanker Braer went aground, discharging about a 100,000 ton cargo onto the ecosystem of Shetland Islands to the north of Scotland. The accident resulted from the failure of a marine propulsion system after seawater was ingested in the storm. The blame for this rests on the cost-cutting practices endemic in the industry. 

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Electrical. Glasses are used in the electrical and electronic industries as insulators, lamp envelopes, cathode ray tubes, and encapsulators and protectors for microcircuit components, etc. Besides their abiUty to seal to metals and other glasses and to hold a vacuum and resist chemical attack, their electrical properties can be tailored to meet a wide range of needs. Generally, a glass has a high electrical resistivity, a high resistance to dielectric breakdown, and a low power factor and dielectric loss. 

Polysulfones also offer desirable properties for cookware appHcations, eg, microwave transparency and environmental resistance to most common detergents. Resistance to various sterilizing media (eg, steam, disinfectants, and gamma radiation) makes polysulfones the resin family of choice for many medical devices. Uses in the electrical and electronic industry include printed circuit boards, circuit breaker components, connectors, sockets, and business machine parts, to mention a few. The good clarity of PSF makes it attractive for food service and food processing uses. Examples of appHcations in this area include coffee decanters and automated dairy processing components. 

Synthetic polymers are best known for their insulating dielectric properties which have been exploited for numerous applications in both the electrical and electronic industries. It was found recently that some polymers can also be rendered conductive by an appropriate treatment, thus opening the way to a new field of applications of these materials (2, 3). Usually, electrical conductivity is obtained by doping a neutral polymer, rich in unsaturation, with donor or acceptor molecules. These polymers are rather difficult to synthesize, which makes them very expensive besides they are often sensitive to environmental agents, like oxygen or humidity, thus restricting their practical use to oxygen-free systems. 

Uses The electrical and electronics industries are the largest users. It is used also in blender housings, kitchen utensils and babies milk bottles. The physical properties are improved by stretching to form crystalline polymers like "Lexan". 

In many high temperature applications in the electrical and electronics industry, the refractory metals arc protected by a vacuum or an inert gas, so that oxidation is not a problem. However, for most other high temperature applications, poor oxidation resistance has limited use. The oxides ol [he refractory metals, rather than existing as tight, protective barriers, stiller from porosity at moderately elevated temperatures, volatility at higher temperature, and spalling of ihe oxide scales away from the substrate, especially al corners and edges. 

Sheet Mica. Good quality sheet mica is widely used for many industrial applications, particularly in the electrical and electronic- industries, because of its high dielectric strength, uniform dielectric constant, low power loss (high power factor), high electrical resistivity, and low temperature coefficient Mica also resists temperatures of 600-lX)0JC. and can be easily machined into strong parts of different sizes and shapes,... 

Electrical and Electronic. There are many industries where adhesives must perform several special functions in addition to their primary function of bonding or joining. These industries often have test methods, specifications, and nomenclature that are unique and somewhat foreign to adhesive formulators. One such industry is the electrical and electronic industry. 

The electrical and electronic industries are generally lumped into one since it is difficult to place boundaries between the two, and they often have similar, if not identical, requirements. The electrical industry is comprised of manufacturers of motors, transformers, meters, etc. It is a large, stable industry with demands for many types of adhesive products. 

Adhesives are used in the electrical and electronic industries in a variety of different ways, from holding microcomponents in place on a circuit board to bonding coils in large power transformers. Reliability is always a concern, since bond failure could lead to component failure, which in turn leads to equipment failure and then possibly to a massive system failure. A system in this industry could be a commercial aircraft s electrical system or the power distribution system in an urban city. 

TABLE 1.5 Representative Adhesive Applications for the Electrical and Electronic Industries... 

In hot mixing or elevated-temperature curing of an epoxy system, vapor pressure could also be of concern relative to the quality of the adhesive bond. If the components in an epoxy system become too hot, boiling can occur, resulting in gas bubbles. If gas bubbles become trapped in the cured adhesive film, they can lead to reduction of cohesive strength and stress risers. For many adhesive applications, particularly those in the electrical and electronic industries (due to possible ionization of air voids), complete removal of any gas bubbles from the epoxy is essential. 

In certain applications, such as in the electrical and electronic industries, adhesive systems must have a degree of electrical and/or thermal conductivity. Electrical conductivity is, of course, important in adhesives that must make electrical interconnection between components and in adhesives that must provide electromagnetic or radio-frequency interference (EMI and RFI) functions. 

The active chlorine is capable, under certain conditions, of blocking reactions with Lewis base catalysts. The main effect of high chlorine content is to reduce system reactivity and crosslink density. Chlorine may also cause corrosion of delicate substrates. Chlorine content is a common test for epoxy resins in the electrical and electronic industries. 

More Mo is consumed annually than any other refractory metal. The major use for Mo is as an alloying element in alloy steels, tool steels, stainless steels, Ni-based and Co-based superalloys. In these materials, it increases the hardenability, toughness, high-temperature strength, and corrosion resistance. Molybdenum is important in the missile industry, where it is used for high-temperature structural parts, such as nozzles, leading edges of control surfaces, support vanes, struts, reentry cones, radiation shields and heat sinks. In the electrical and electronic industries. Mo is... 

Casting. Molding Compounds, and Tooling. Epoxy resins maintain a dominant position in the electrical and electronic industry for casting resins, molding compounds, and potting resins. Their... 

In some applications in the electrical and electronics industries PES is being used because its properties are necessary in the manufacture of the component rather than its in-service requirement. For example, in one established application PES is used for the coil formers of a line output transformer that is used in a oolour TV set to produce the 2 Kv for operation of the electron beam During normal use, temperatures above 173 F are rarely reaohed and therefore on tMs ba s alone several materials were contenders, with PES an expensive option PES was selected eventually because the former must withstand the 340-360°F baking temperature required to shrink the stretched polycarbonate interleaving film on the windings, and because if offered satisfactory electrical performance during use. The non-biu ning characteristics of PES are an added bonus for this type of application ... 

Plastics, A Material of Choice for the Electrical and Electronic Industry—Plastics Consumption and Recovery in Western Europe, Association of Plastics Manufacturers of Europe, Brussels, 1995. 

Bismaleimide resins are extensively used in multilayer printed circuit boards. They can also be used in insulation fibres for protective clothing. Due to their ability to adhere and retain adhesive strength at high temperature, bismaleimides are widely used as a base material for flexible printed circuit boards in the electrical and electronics industries. Bismaleimides are often linked with rubber chains for use as flexible linking molecules to reinforce the rubber compound for tyre applications. The double bond of bismaleimides readily reacts with all hydroxy or thiol groups found on the matrix to form a stable carbon-sulfur, carbon-nitrogen or carbon-carbon bond. 

More than half of all sales of brominated FRs by volume were targeted at the electrical and electronics industries by the beginning of the present decade, with second place taken by building and construction at just over 30%, according to the Bromine Science and Environmental Forum, an organisation of brominated FR manufacturers. 

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