The use of copper powders recycled from printed wire boards to manufacture a conductive epoxy adhesive

The feasibility of using copper powders recovered from printed wire boards (PWB) to produce the electrically conductive adhesive was studied with the conductivity measurement, the differential scanning calorimetry (DSC), and the lap shear strength measurement. It was shown that the simple rinsing and etching procedure could effectively remove the impurity and the surface copper oxide, and greatly improve the conductivity of the recycled copper flakes. From the addition of a small amount of nickel powders, as much as 270 parts recycled Cu (per hundred parts adhesive resin as the reference) could be used to form a good conductive adhesive. The formulated adhesive had a strong lap shear strength and a good conductivity after thermal exposure. In addition, the results of DSC analyses indicated that the presence of copper powders increased the curing exotherm and affected the curing characteristics of the adhesive resin.