Adhesives, electrically conductive prevention

The two metallizations most commonly used to fabricate transducers on AW devices are gold-on-chromium and aluminum. Au is often chosen for chemical detection applications because of its inertness and resistance to corrosion a layer 100-200 nm diick is necessary to provide adequate electrical conductivity. Unfortunately, the inertness of Au also prevents its adhesion to quartz and other oxides utilized for AW device substrates. Therefore, an underlayer of Cr (2-10 nm thick) is utilized to promote the adhesion of Au to the substrate the electropositive (reactive) nature of Cr allows it to form strcxig bonds with oxide surfaces, while alloying between the Cr and Au chemically binds the two metal layers... 

A fourth generation of electrically conductive adhesives based on cyanate esters and modified cyclo-olefin thermoset (MCOT) resins was introduced in the 1990s. These resins were specially formulated for low moisture absorption, high thermal stability, and low stress to be compatible with solder-reflow conditions. They were developed to prevent or reduce the so-called popcorn effect, a failure mode attributed... 

In the past 20 years bendable and disposable medical electrodes evolved. Instead of a rigid metal plate serving as electrode, a metal mesh, foil or carbon impregnated rubber or vinyl, ensuring more flexibility in the electrode structure, are used. A conductive adhesive layer, usually in the form of a gel, is disposed on the conductive side of the material to provide a good electrical conductive contact between the conductive material and the patient s skin. Connection between the conductive material and an electrical stimulation device is provided by means of an electrical wire. Instead of wires, pressure buttons on top of the conductive material may alternatively be used. The outside face of the conductive material is covered with a nonconductive material to prevent electrical contact. 

Free radicd polymerization of 2-acrylamido-2-methyl propane sulfonic add (Lubtizol s AMPs monomer) or its soluble salt also yields sheet form, ionically conductive adhesive for use in biomedical electrodes (13). This mat ial exhibits uniform conductivity preventing the hot spots associate with localized current Additionally, the AMPs -based materials are inheroitly electrically conductive, not requiring the use of additional additives (e.g., salts). 

Inorganic (non-polymer) basecoats can provide layers to aid in adhesion (adhesion layer or glue layer) of a film to a surface. For example, in the Ti-Au metallization of oxides, the titanium adhesion layer reacts with the oxide to form a good chemical bond and the gold alloys with the titanium. The layers may also be used to prevent interdiffusion (diffusion barrier) between subsequent layers and the substrate. For example, the electrically conductive compound TiN is used as a barrier layer between the aluminum metallization and the silicon in semiconductor device manufacturing. 

Preventing degradation of the electrical or thermal conductivity of the filler or the filled cured adhesive. 

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