Adhesives, electrically conductive categories

Figure 42 Main categories of anisotropically conductive adhesives (a) materials anisotropic before processing (b) adhesives containing metallic spheres with controlled diameter (c) mixture of collapsible conductive filler and lower size non-conductive spacers (d) the reverse situation with spacers larger than the electrically conductive...

When two dissimilar materials are brought into contact, as is the case in an adhesive bond, the resulting electronic attraction can be caused by any combination of the interactions listed above. The attractive forces across the interface have been classified into two broad categories dispersion and polar. These forces have been discussed by Atkins [86] and Wake [87]. The polar component results from electric dipoles associated with specific atom pairs or functional groups on the materials surface. The dispersion component results from loosely bound electrons such as those in the conduction band of metals or simply from electrons in the atoms or molecules in the material. 

Similar to the Types la and lb fibers, the Type Ic fibers consist of a thin, conductive metal layer electrodeposited upon a carbon base fiber (see Figure 5). Their manufacture is described by Morin(27) and by HaU and Ando(25). The paper by Hall and Ando provides a good overview of their properties and characteristics. Nickel plated exPAN carbon fiber are typical of the Type Ic fibers that are readily commercially available. General uses for Type Ic fibers are in ESI shielding, conductive adhesives and paints, conductive fabrics, and high performance electric contacts(2P). They are included in the Type 1 category because their conductivity is characteristically metallic. Thus, by this convention they appear in the Type 1 classification while the various other carbon fibers fall into the Type 2 category. 

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