Corrosive electronic devices

Uses. In spite of unique properties, there are few commercial appUcations for monolithic shapes of borides. They are used for resistance-heated boats (with boron nitride), for aluminum evaporation, and for sliding electrical contacts. There are a number of potential uses ia the control and handling of molten metals and slags where corrosion and erosion resistance are important. Titanium diboride and zirconium diboride are potential cathodes for the aluminum Hall cells (see Aluminum and aluminum alloys). Lanthanum hexaboride and cerium hexaboride are particularly useful as cathodes ia electronic devices because of their high thermal emissivities, low work functions, and resistance to poisoning. 

Although less widely reported than the effects of vapours, contact corrosion has been a serious problem in packaging and in electronicsAs miniaturisation and sophistication of electronic devices has increased, the hazard presented by corrosion is often the limiting factor inhibiting the attainment of expected levels of reliability. 

SACHEM Inc., located in Cleburne, Texas, is a producer of high-purity bulk chemicals for companies that have high-purity requirements in their chemical processing. As stated in Workplace Scene 1.2, one of their products is tetramethylammonium hydroxide (TMAH), which is sold to semiconductor industries. The analysis of TMAH for trace anions such as chloride, nitrate, nitrite, and carbonate is critical for SACHEM s quality control laboratory. If these ions are present on the integrated circuit boards manufactured by one of their semiconductor customers, they may cause corrosion severe enough to affect the functionality and performance of the electronic devices in which the circuit boards are used. In SACHEM s quality control laboratory, ion chromatography procedures have been developed to measure the anion concentrations in TMAH. Because the concentration levels are trace levels, a clean room environment, like that described in Workplace Scene 1.2, is used. A special procedure for carbonate analysis is required so that the absorption of carbon dioxide from the atmosphere can be minimized. 

The protection of microelectronics from the effects of humidity and corrosive environments presents especially demanding requirements on protective coatings and encapsulants. Silicone polymers, epoxies, and imide resins are among the materials that have been used for the encapsulation of microelectronics. The physiological environment to which implanted medical electronic devices are exposed poses an especially challenging protection problem. In this volume, Troyk et al. outline the demands placed on such systems in medical applications, and discuss the properties of a variety of silicone-based encapsulants. 

Hard, brittle metal prevents corrosion in steel by a process known as galvanization used also to make dry-cell batteries and electronic devices. 

Another example of an industrially relevant CVD process is the production of tungsten (W) films on various substrates for (a) wear and corrosion protection and (b) diffusion barriers in electronic devices. One CVD method for depositing tungsten is through the reduction of WFs with hydrogen, which follows the overall reaction ... 

Corrosivity of combustion gases can be detrimental to electronic devices as well as communication equipment. Acidity tests are used to measure the corrosivity of combustion gases. The acidity tests are specified in the IEC 60754-1,30 EN 50267-1,31 and BS 6425-132 standards. These tests are conducted on the cable insulation or jacketing materials instead of finished cables and are useful to distinguish between halogen and halogen-free materials. In these tests, the sample is heated to 800°C for 20 min and the amount of halogen acid gas (except hydrofluoric acid) is measured with an upper allowed limit of 0.5 wt %. Alternatively, IEC-60754-2,33 EN 50267-2,34 and... 

All books, reviews, and entries on CPs describe the potential applications. Chandrasekhar and others ° have reviewed in comprehensive fashion the applications of CPs, including batteries sensors electro-optic and optical devices microwave- and conductivity-based technologies electrochromic devices electrochemomechanical and chemomechanical devices corrosion protection semiconductor, lithography, and electrically related applications— photovoltaics, heterojunction, and photoelectrochemical cells capacitors electrolytic and electroless metal plating CP-based molecular electronic devices catalysis and delivery of drugs and chemicals membranes and LEDs. 

Typical transfer molding compositions for encapsulation of electronic devices are mixtures of an epoxy novolac resin, a phenolic resin hardener, a catalyst, large amounts of inorganic filler (e.g., Si02) flame-retardant ingredients, internal lubricants, carbon black, and sometimes other additives such as getters to trap ionic impurities (34,35), corrosion-protection materials, and stress-relief ingredients. 

Gold is file most well known of all precious metals, forming the basis of many currencies and also used for decorative jewellery. Gold has historically been viewed as a very chemically inert material chlorine is one of only a few substances that react with it. This property, coupled with its high electrical conductivity, makes it an ideal material for corrosion resistant wires and contacts in electronic device applications. Therefore, it came as some surprise when it was found that Au in NP form... 

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