Electroless Deposition: History, Status and Future Directions

Electroless deposition of metals, oxides, salts and other compounds is very important for many industrial and technological applications.  These sophisticated processes have been used in different applications throughout many centuries, even though they were not recognized as such.

Based on the archeological discoveries some of the electroless deposition processes e.g. gold and silver were used in the early Mediterranean civilizations. Reduction of Ni(II) ions to the elemental nickel with hypophosphite was first discovered by Wurtz in 1846 [1].  Liebig discovered the reduction of Ag(I) to Ag^o, using the formaldehyde as a reducing agent [2]. In 1948, Brenner was the first who described proper conditions for the electroless deposition of nickel using hypophosphite as a reducing agent [3].  Significant developments in this area occurred in the second half of the 20^th century and until now [4,5].  Metals of interest include of all the metals and alloys which can be electrodeposited from the aqueous solution i.e. Ni, Cu, Ag, Au, Pd etc, with particular attention given to nickel, copper, gold and silver.

Although many electroless depositions of nickel, cobalt, copper, silver, gold or similar are used in different industrial processes, there are many aspects of these processes that are not yet fully understood.  It is well established that these processes are electrochemical by the nature, however, the mechanisms of the reactions governing the electroless deposition are not yet generally accepted by the researchers.

In this presentation a historical overview of the electroless processes used throughout centuries until present days will be given.  Then, a classification of different electroless processes i.e., galvanic deposition, autocatalytic deposition and contact deposition will precisely be defined. Mechanisms of the electroless deposition and future directions for the electronic, biomedical, energy device, automotive and aero-space applications will be discussed.

Refernces:

1. A. Wurtz, C.R. Acad. Sci. Paris, 18 702 (1884); 21 149 (1845).
2. B. Liebeg, Ann. Chim et Phar. 14 140 (1835).
3.  A.Brenner, G.E.Riddell, Proc.Am.Electropl.Soc., 33 16 (1946).
4. G.O. Malloy, J.B. Hajdu, Electroless Plating: Fundamentals and Applications, AESFS, Orlando, Florida, 1990.
5. S.S. Djokić, Electroless deposition of metals and alloys, Modern Aspects of Electrochemistry, No. 35, Ed. B. E. Conway, R.White and J.O’M Bockris,. pp.51-120, Kluwer Academic/Plenum Publishers, N.Y 2002.