Definition

Electroless plating deposits metal through an autocatalytic chemical reduction reaction, without external electrical current. The process provides uniform thickness regardless of geometry (unlike electroplating which varies with current density). Electroless copper is used to make drilled holes conductive before electroplating. Electroless nickel (in ENIG) provides a barrier layer with phosphorus content affecting properties. Electroless processes require precise chemistry control but enable plating on non-conductive substrates and complex geometries.