Dielectric
“A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material, as in a conductor, but only slightly shift from their average equilibrium positions causing dielectric polarization. Because of dielectric polarization, positive charges are displaced toward the field and negative charges shift in the opposite direction. This creates an internal electric field that partly compensates the external field inside the dielectric. If a dielectric is composed of weakly bonded molecules, those molecules not only become polarized, but also reorient so that their symmetry axis aligns to the field. “
“Although the term "insulator" implies low electrical conduction, "dielectric" is typically used to describe materials with a high polarizability. The latter is expressed by a number called the dielectric constant. A common, yet notable example of a dielectric is the electrically insulating material between the metallic plates of a capacitor. The polarization of the dielectric by the applied electric field increases the capacitor's surface charge.”
“The electric susceptibility χeof a dielectric material is a measure of how easily it polarizes in response to an electric field. This, in turn, determines the electric permittivity of the material and thus influences many other phenomena in that medium, from the capacitance of capacitors to the speed of light.”
Recent US Patents
10/5/2010
7,807,066
Method of Manufacturing a Porous Resin Substrate having Perforations and Method of Making a Porous Resin Substrate including Perforations having Electrically Conductive Wall Faces
Higher frequencies and higher speeds in electronics require materials with lower dielectric constants. Porous resin materials have lower dielectric constants than nonporous resin. Thus foams are logical candidates for low dielectric materials. In some applications the material is perforated and filled with a conductive material to conduct electrons through the material. Perforating foams usually results in a solid surface with damaged and conductive material. Uenoyama et al have developed a method of manufacturing a perforated porous resin substrate with a constant low dielectric constant by perforating a porous fluoropolymer material and etching the perforation with a sodium/naphthalene etchant solution. This results in a degenerated surface which is removed by hydrogen peroxide oxidation. The result is a clean, porous surface which can hold a catalyst for electroless plating and forming a conductive surface through the material.