Portable electronic products

Crystalline chemical and electrochemical manganese dioxides are employed in billions of cells of Leclanche type which remain today probably the most popular and inexpensive power sources for wrist watches, cameras, flashlights, portable electronic products, etc. Worldwide annual output of power sources is estimated at 40 bln. pieces more than 70% of them are those operating with Mn02 chemistry as a cathode active material or a... 

Heat dissipation is a performance limiting parameter in many portable electronic products. 

Portable electronic products are exposed to more severe conditions than ever before. As a result, they need higher reliability for the circuits as listed in Table 61.3. In the case of portable telephones, they are often carried in the owner s pocket, where they may be exposed to a variety of conditions, including continuous vibration, mechanical shock, temperature, humidity, pocket Unt, and even perspiration. Other portable electronic products, such as digital cameras, PDAs, and notebook computers, could be exposed to similar conditions. 

A design for the equipment housing is made according to the final product concept. (This should sometimes be done independently in the case of consumer applications, especially for portable electronic products.)... 

It is common for a flexible circuit to be coimected to other circuit boards. However, more traces and a higher density of the connections are then required. The basic design of the end products automatically determines the placement of specialty components such as keyboards, switches, antennas, actuators, printer heads, sensors, microphones, speakers, and buzzers in small electronic applications. Although these components do not require numerous wires, they do need high-density connections due to the extreme miniaturization of portable electronic products. 

The aggressive and growing market for portable electronic products, as well as the environmental necessity for zero-emission vehicles, i.e., electric vehicles, has motivated researchers to develop electrochemical power sources characterized by high energy density, long life-cycle, reliability, and safety. A recent breakthrough in the field was the commercialization of rechargeable lithium batteries, the lithium-ion batteries, which are now produced at a rate of about a million units per month. 

For prachcal applicahons, different electrodes and different applications need different types of electrolytes. In the case of Shinestar products, there are over 10,000 electrolytes targeted for different purposes. Consequently, Shinestar electrolytes are widely used in lithium-ion batteries for mobile phones, laptop computers, power tools, model aircraft, and other portable electronic products. Since 2010, Shinestar electrolytes have also been used widely in power lithium-ion batteries based on positive electrodes such as LiFeP04, LiMn204, and Li[Ni,.COyMni , y]02. Electric buses using these electrolytes in their batteries were successfully operated during Shanghai World Expo in 2010. 

Success in the battery market depends largely on four factors, noted in Figure 10. The market for batteries in Table 1 is directly related to the applications they serve, such as automobiles, cellular phones, notebook computers, and other portable electronic devices. The growth in any particular segment follows closely the introduction of new devices powered by batteries. The introduction of new materials with higher performance parameters gives the various designers freedom to incorporate new functionality in present products or to create new products to... 

Apart from hydrocarbons and gasoline, other possible fuels include hydrazine, ammonia, and methanol, to mention just a few. Fuel cells powered by direct conversion of liquid methanol have promise as a possible alternative to batteries for portable electronic devices (cf. below). These considerations already indicate that fuel cells are not stand-alone devices, but need many supporting accessories, which consume current produced by the cell and thus lower the overall electrical efficiencies. The schematic of the major components of a so-called fuel cell system is shown in Figure 22. Fuel cell systems require sophisticated control systems to provide accurate metering of the fuel and air and to exhaust the reaction products. Important operational factors include stoichiometry of the reactants, pressure balance across the separator membrane, and freedom from impurities that shorten life (i.e., poison the catalysts). Depending on the application, a power-conditioning unit may be added to convert the direct current from the fuel cell into alternating current. 

Recovery of metals such as copper, the operation of batteries (cells) in portable electronic equipment, the reprocessing of fission products in the nuclear power industry and a very wide range of gas-phase processes catalysed by condensed phase materials are applied chemical processes, other than PTC, in which chemical reactions are coupled to mass transport within phases, or across phase boundaries. Their mechanistic investigation requires special techniques, instrumentation and skills covered here in Chapter 5, but not usually encountered in undergraduate chemistry degrees. Electrochemistry generally involves reactions at phase boundaries, so there are connections here between Chapter 5 (Reaction kinetics in multiphase systems) and Chapter 6 (Electrochemical methods of investigating reaction mechanisms). 

Cadmium is widely used in industry for metal coating, pigments and paints, batteries, and in solder alloys. Its principal use is in the production of nickel-cadmium batteries required for portable electronic and electrical equipments. According to the U.S. Geological Survey, the total world refinery production in 1997 rose to 19,500 tons from 18,900 tons a year. 

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