Advantages over organic resists

Sihcones (qv) have an advantage over organic resias ia their superior thermal stabiUty and low dielectric constants. Polyurethanes, when cured, are tough and possess outstanding abrasion and thermal shock resistance. They also have favorable electrical properties and good adhesion to most surfaces. However, polyurethanes are extremely sensitive to and can degrade after prolonged contact with moisture as a result, they are not as commonly used as epoxies and sihcones (see Urethane polymers). 

On account of their higher electrical conductivity, silicate esters have clear advantages over organic polymers as binders. The resistivity of a one-pack silicate ester zinc dust paint is ca. 1 x 10 O cm, i.e., two to three orders of magnitude lower than that of commercially available purely organic systems with a comparable zinc content. 

Poly(alkoxyfluorophosphazene)s have advantages over organic elastomers or silicone rubber, because of their low transition temperatures and unusual resistance to oils, fuel, hydraulic fluids, and so on. Thus, for example. Firestone Tire and Rubber Company supplied different products from them, for example, O-rings, gaskets, hydrocarbon fuel hoses, and fire-resistant foam rubber devices. " ... 

Recently, nonionic acid precursors based on nitrobenzyl ester photochemistry have been developed for chemically amplified resist processes (78-80). These ester based materials (Figure 8) exhibit a number of advantages over the onium salt systems. Specifically, the esters are easily synthesized, are soluble in a variety organic solvents, are nonionic in character, and contain no potential device contaminants such as arsenic or antimony. In addition, their absorption characteristics are well suited for deep-UV exposure. 

These Deloxan beads have an inert siloxane matrix which is advantageous over other adsorbents such as activated carbon or organic polymer-based resins and fibers because (1) valuable API product is not adsorbed and lost as is the case when activated carbons are used and (2) they are chemically resistant to most solvents and stable over a wide pH range (0-12). 

What does the future hold A number of new antipseudomonas /3-lactam antibiotics are being developed at the present time (see Table 7.1). Whether these compounds will hold significant advantages over carbenicillin is yet to be shown. The /3-lactam antibiotics hold great promise because of their low toxicity however, a good anti-pseudomonas compound requires MICs below 10 fig/ml and good pharmacokinetic properties. The compound should also be stable to /3-lactamase enzymes and show resistance to organism habituation. 

Another demountable cell is pictured in Fig. 4. The plates are thin wafers of silver chloride, which is transparent to infrared radiation. This cell has advantages over the salt cell in that the silver chloride disks are more resistant to breakage than NaCl plates, they are less expensive, and they are not affected by water. Because silver chloride is photosensitive the wafers must be stored in the dark to prevent them from turning black. Because one side of each wafer is recessed, the thickness of the sample can be varied according to the manner in which the cell is assembled. The disks are cleaned by rinsing them with an organic solvent such as acetone or ethanol and wiping dry with an absorbent paper towel. 

Silanisation has many advantages over the use of organic polymers due to its high mechanical strength, resistant to solvents, stability, ease of handhng and the fact that the structure is more or less constant at varying pH and temperature. 

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