Mechanism of electrical conduction through anisotropically conductive adhesive films

Anisotropically conductive adhesive films (ACFs) which had different amount of electrically conductive particle contents and insulating particle contents were offered for measurement of electrical resistance between electrically conductive glass substrates and flexible printed circuits (FPCs) connected by using these ACFs. As a result, the electrical resistance for samples using ACFs containing electrically conductive particles was proved to he low, and also that for samples using ACFs containing insulating particles or no particles was proved to be considerably lower than we had expected. On the other hand, after high temperature and high humidity treatment or temperature cycle treatment, the electrical resistance for samples using ACFs containing electrically conductive particles did not change so much, but that for samples using ACFs containing insulating particles or no particles changed significantly, that is, it increased remarkably. From these facts, we presumed that there were two kinds of electric current passing through ACFs: one passing through electrically conductive particles and the other not passing through them; the current passing through electrically conductive particles did not change so much even after high temperature and high humidity treatment or temperature cycle treatment, but the current not passing through electrically conductive particles significantly reduced after the treatment mentioned above. On the basis of the above result, the role of conductive particles in ACFs was considered.