Silver-Palladium Surfaces
This surface finish is frequently being used with ceramic SMT capacitors. It possesses very good wetting characteristics, but it also dissolves, when in contact with liquid solder, very quickly into the bath. That is the reason why components with this surface should have, below their AgPd surface, a nickel barrier layer. If this should not be the case, the danger is present that, with prolonged wetting times, the AgPd layer will completely dissolve into the solder, and a substance-to-substance bond between component and pad may not come to be.