Electrical Conductivity and Fillers

Electrically conductive adhesives may be isotropic (conduction equally in all directions) or anisotropic (conduction in the z-direction only). Both types are widely used in the assembly and packaging of electronics. 

Optimum euring conditions are also important in attaining the highest conductivity. The improvements in eleetrieal eonductivity resulting from increased time and temperature cure conditions foracommercial silver-filled epoxy adhesive are found in Table 2.3.1 1 This low temperature-curing adhesive is used in assemblies having temperature-sensitive components. 

Electrical conductivities of fully cured, silver-filled epoxies are quite stable, decreasing only slightly when measured at elevated temperatures (Fig. 2.13, Table 2.4). Extended cures and aging at 150°C for 1,000 hours have even improved their conductivities. 

Anisotropic conduction. Electrical conductivity in anisotropic adhesives occurs by a different mechanism than for isotropic adhesives. Although metal fillers are also used, they are used in mueh lower amoimts (0.5% to 

Data Provided by Thermoset, Lord Chemical Products. 

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