Electrical contacts on nickel plated aluminium: the state of the art

A direct nickel plating procedure for aluminum is described. It is shown that the main disadvantage of aluminum as far as electrical applications are concerned, namely its unstable contact properties, can be cured by direct nickel plating. This economical solution meets all standards, including the highly demanding standards of the airplane industries. Untreated aluminum surfaces and coated aluminium are considered. Instead of the several steps imposed by the standard procedures, the procedure requires only two basic steps: surface activation and electroplating. The electrolytes are selected so as to warrant pure nickel layers free of residual internal stresses. The method (developed for wires) through liquid contacts allows high current densities, thereby a rapid plating (typically 1 mu m/s) and a high yield. The nickel layer obtained with this procedure is globular, with nodules about 0.5 mu m in diameter, which favors better electrical contacts. The improved properties brought by recent developments of this technology are discussed, and the severe certification tests performed for use on airplanes are reported. In particular, the test conditions were: 500 heat cycles, tang current densities in the vicinity of 150 A/cm/sup 2/, (up to 250 A/cm/sup 2/), connector lug temperature up to 165 degrees C, and cable temperature near 210 degrees C.<<ETX>>

[1]  M. Braunovic.  Effect of fretting on the contact resistance of copper, aluminum and nickel-coated aluminum wire connections☆ , 1986 .

[2]  M. Braunovic,et al.  Effect of Contact Aid Compounds on the Performance of Bolted Aluminum-to-Aluminum Joints Under Current Cycling Conditions , 1986 .

[3]  R. S. Timsit,et al.  Interdiffusion at Bimetallic Electrical Interfaces , 1986 .

[4]  M. Braunovic,et al.  Evalutation of Different Types of Contact Aid Components for Aluminum-to-Aluminum Connectors and Conductors , 1985 .

[5]  D. Newbury.  What is causing failures of aluminum wire connections in residential circuits , 1982 .

[6]  M. Braunovic,et al.  Effect of Current Cycling on Contact Resistance, Force, and Temperature of Bolted Aluminium-to-Aluminium Connectors of High Ampacity , 1981 .

[7]  D. Newbury,et al.  Observations on the Mechanisms of High Resistance Junction Formation in Aluminum Wire Connections. , 1980, Journal of research of the National Bureau of Standards.

[8]  R. Timsit,et al.  Some Fundamental Properties of Aluminum-Aluminum Electrical Contacts , 1980 .

[9]  M. Braunovic,et al.  Effect of Fretting on the Contact Resistance of Aluminium with Different Contact Materials , 1979 .

[10]  M. Braunovic,et al.  The Effect of Surface Segregation of Mg on the Contact Resistance of Al-0.5-Percent Mg , 1977 .

[11]  Norman T. Bond,et al.  Nickel Plating for Improved Electrical Contact to Aluminum , 1973 .

[12]  S. Roques,et al.  Développement de l’utilisation de l’aluminium dans les câbles à usage aéronautique , 1988 .

[13]  J. Plewes,et al.  Properties of electroplated nickel alloy films for contacts , 1987 .

[14]  R. Timsit.  Intermetallics growth at Alα-brass interfaces , 1985 .

[15]  J. Lefèbvre.  Le nickelage. Un nouveau traitement de surfaces pour les applications électriques de l’aluminium , 1982 .