Deposition Mechanism of Electroless Pd Plating Using Formic Acid as a Reducing Agent

Gold plating is used for many surface treatment cases of contact and joints within electronic components to increase the contact performance and the corrosion resistance. However as a result of mutual dispersion of gold and the base metal, or reduction in joint strength due to ductility of intermetallic compound of gold-zinc, these problems have lead the researchers to look into electroless palladium plating has been under investigation. When for the reduction agent the sialic acid and phosphorous acid are used a skin coating is precipitated within which phosphorous is eutectogenic. Along with increase in the amount of this eutectogenic phosphorous the coating hardness and electrical resistance are increased leading to poor solder ability. In this paper the electroless palladium plating is discussed in which the ethylene diamine and formic acid act as the reducing agent. Through their study the precipitation mechanism with measurement of the consumption of formic acid HCOOH with Pd deposition are reviewed. Effects of bath components and plating conditions on deposition rate are plotted.