Conformal coatings materials

Typical conformal coating materials offer protection against some environmental hazards, but no single fluid offers protection against all of them. 

In any event it is important to choose the right encapsulant to protect components from contamination, humidity and shock. Cyanoacrylates and epoxies are coimnonly used as encapsulating and conformal coating materials. 

TABLE 41.1 Conformal Coating Materials and Their Characteristics ... 

Insulation resistance is the integrated effect of both volume and surface resistivity according to the ASTM definition (Ref 8). The measured bulk resistance will depend upon the nature of the laminate, solder mask or conformal coating material under investigation, and the degree of cure. It will also be affected by soldering flux/paste... 

Ion plating is used to deposit hard coatings of compound materials, adherent metal coatings, optical coatings having high densities, and conformal coatings on complex surfaces. 

Mewtonian andMon-Mewtonian Materials. A Newtonian material s viscosity is shear-independent, whereas non-Newtonian materials are shear-dependent (Eig. 7). Eor most potting materials, a Newtonian material is preferred because the material is required to flow under all electronic components, but not be susceptible to shear. However, when flowable material is used for conformal coating appHcations, a non-Newtonian material with thixotropy agent added is desired since the material should flow on the electronic substrate but stop at the edge without creeping or mnover at the circuitry. 

Microemulsions. Systems comprising microwater droplets suspended in an scCO T oil phase can be achieved with the use of appropriate surfactants, of which the best appear to be fluorinated. Microemulsions in supercritical hydrofluoro carbons are also possible. Potential may also exist for speciality coatings via low concentration solutions of fluorinated products in supercritical fluid for, e.g., thin-fitm deposition, conformal coatings, and release coatings. Supercritical CO2 will dissolve in formulated systems to improve flow and plasticize melt-processable materials to improve melt-flow characteristics and lower the glass transition temperature. 

Conformal coatings -for electronic packaging [PACKAGING - ELECTRONIC MATERIALS] (Vol 17) -in electronic packaging [EMBEDDING] (Vol 9)... 

Two types of coating materials are used in electrical and electronic equipments. One is conformal coating, the other is junction coating resin. These coating materials also occupy an important place in the electrical and electronic fields. 

The nanowires themselves can be used as templates to generate the nanowires of other materials. The template may be coated onto the nanowire (physically) forming coaxial nanocables [316a], or it may react with the nanowires forming a new material [317a,b]. In the physical (solution or sol-gel coating) approach, the surfaces of the nanowires could be directly coated with conformal sheaths made of a different material to form coaxial nanocables. Subsequent dissolution of the original nanowires could lead to nanotubes of the coated material. The sol-gel... 

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