CORROSION AND PROTECTION OF A CONDUCTIVE SILVER PASTE

One of the possible uses for a conductive paste is as an adhesive in i nterconnect technology that could replace PbSn solder. The interconnec tions are expected to perform under a variety of environmental conditi ons, and with an applied voltage. Thus knowledge of their corrosion an d dissolution resistance is of utmost importance. This is a study of t he dissolution and protection of polymer/metal composite films, prepar ed with a high loading of silver or gold particles. Electrochemical te sts were conducted in a droplet of triple-distilled water with or with out benzotriazole (BTA) and BTA derivatives. Results indicate that, in spite of some protection obtained by the polymer, silver paste dissol ution at high anodic potentials is rapid, reaching values of 10(-1) A/ cm(2), which corresponds to a catastrophic silver removal rate of at l east 35.6 nm/s. With a reservoir of azole in the corrosive environment , this rate can be reduced by up to five orders of magnitude. This azo le effect greatly reduces the probability of electrolytic silver migra tion, but the Ag dissolution rate is still higher than the anodic acti vity shown by Au paste under the same conditions.