Simultaneously Improving Electrical Properties and Stabilizing Contact Resistance of Electrically Conductive Adhesives by Using Aminoaldehydes

In order to simultaneously improve the conductivity and stabilize the contact resistance of electrically conductive adhesives (ECAs) containing silver flakes, different types of aminoaldehydes as multifunctional additives, N, N-dimethyl-4-aminobenzaldehyde (DABA), benzaldehyde (BA) as a comparison, and formamide (FA), were introduced into ECAs formulations. The results showed that when the optimal levels of FA, BA, and DABA were individually added into ECAs, the decrease in the resistivities of the ECAs were 34.8%, 67.2%, and 41.7%, respectively, compared to the control sample. This is because, during the curing process, the aldehyde acts as a reducing agent and reduces the oxidized silver flakes. Furthermore, the ECAs with FA or DABA had better contact resistance stability than that of the control sample under the condition of 85 degrees C/85% relative humidity, but ECAs with BA could not stabilize the contact resistance on tin finish, The results indicate that FA and DABA can be adsorbed onto the tin surface and inhibit the occurrence of the galvanic corrosion on the interface between ECA and tin finish. The rheological results showed the processability of ECAs with FA, BA, and DABA were better than that of the control sample. However, the shear strength of ECAs with BA and DABA slightly declined.