Investigation of properties and curing process of silver paste electrically conductive adhesives (ECAs)

Silver paste electrically conductive adhesives (ECAs) are adhesives containing silver particles and resin matrix, forming by specific technology. The conductive adhesive has better printing performance than the sold er paste, which can meet the requirements of higher precision. However, the relationship between curing process and properties of conductive adhesive has not been developed completely and it is time to explore a kind of conductive adhesive which is suitable for fast curing. The effects of curing time and temperature of conductive adhesives on electrical and mechanical properties are studied in this paper. Several analysis methods are used to test scanning electron microscope photograph, electrical and mechanical properties and so on. Besides, the TG and DSC curves are studied to seek the appropriate curing temperatures of three conductive adhesives with different volume percentages. The curing process has intluence on the electrical and mechanical properties of the conductive adhesive after curing. When the curing temperature is lower than the temperature of the crosslinking reaction, the curing process is not complete, and the resistivity shows large. The shear strength of the conductive adhesive increases with the increase of curing time. The conductive adhesive can be cured completely when the curing temperature reaches the temperature of crosslinking reaction and the resistivity decreases with the increase of the curing temperature. The shear strength increases with the increase of curing time in the initial stage of curing process and the conductivity and shear strength begin to decrease when the curing time reaches a certain range. Curing temperature over 140 degrees C can be difficult to get good conductivity and shear strength.