Effect of Ag particle size on electrical conductivity of isotropically conductive adhesives

The present work is to introduce nanoparticles in micro-sized metal particles to study particle distribution in polymer matrix. Previous examinations of the silver-filled particles reveal that the micro-sized particle fillers appears as full density silver flakes, while nanoparticle fillers appear as highly porous agglomerates, similar to open-cell foams. Actually little work has been carried out to study the cross-sectional area of a particle-particle-contact in isotropically conductive adhesives (ICA). In this study, transmission electron microscope is chosen as a main measure to analyze the distribution of different-sized particles. The percentage of the nanoparticles varies from 20 wt% and 50 wt% to full percentage within micro-sized particles, and the total metal content in epoxy resin is 70 wt%. So the change of contact area and contact behavior with various volume ratio of nano-sized and micro-sized particles was investigated. At the same time, the electrical resistivity was measured, which is compared with the different level of the filler loading.