Spatial distribution of metal fillers in isotropically conductive adhesives

The de electric conductance of isotropically conductive adhesive (ICA) was studied. Assuming completely random distribution of the metal fillers in the ICA, it was demonstrated that the percolation volume percentage of the metal fillers can be significantly reduced by adding nano-size fillers (nanofillers) into the system originally containing only micro-size fillers (microfillers), However experiments show that, due to the surface tensions, nanofillers tend to gather around microfillers as well as to form clusters themselves so the resistivity of the ICA increases following the increase of the nanofillers' volume percentage. In the present work, these cluster effects are investigated by simulating the detailed random walks of the nanofillers and microfillers in the system. It is concluded that the cluster effects of the nanofillers deteriorate the electric conductivity of the ICA because the microfillers separate from each other so that it is more difficult to form the electrical conduction path in the ICA.