Contact lubricants have been used in electric contacts such as connectors. Contact failures for down size of connector contacts with low contact force and cost down of gold plated are a serious problem to be solved. One solution is the application of lubricants to the contacts. Particularly these contacts are exposed to elevated temperature under reflow treatment in assembling processes. It is an important subject should be clarified that the deterioration phenomenon of increases in contact resistance properties under the reflow. This degradation should be induced by two causes. Namely, one is a surface contamination due to oxidation of diffused small amount of additives through gold plated layer. The other is decomposition of the coated lubricants. In this study, first of all, degradation of contact resistance properties were measured, and change of images of STM for exposure time of high temperature were observed. To clarify more in detail this degradation of the contact resistance, for both clean gold plated surface and heated clean surface were examined by using XPS and AES analysis. As results, contact resistance properties of clean surface were found to degrade for exposure at the elevated temperature. This degradation was found due to oxidation of base metal nickel and cobalt additive to gold plated surface. However, influence of the contact lubrication on the degradation of contact resistance was not recognized. The change of composition of an olefin lubricant was discussed by using STM images. Moreover, growth of oxide film on the clean surface was found as cubic law by using an ellipsometry.

At the present time, as downsizing of connectors causes thin gold plated layer and low contact load, serious problem of degradation of contact resistance property is induced. For these contacts, corrosion of the contacts surface under environment and high temperature as soldering and reflow process should be existed. Oxidation of base metal atoms which are diffused from under layer and additives occurs. Contact resistance increases for both surface contamination and low contact load. In order to resolve these problems and wear of surface, application of contact lubricants is useful and effective. However, degradation of the lubricants under such reflow process as high temperature possibly occurs. Therefore, in this study, from view point of change of lubricant quality as viscosity, weight loss, polymerization, oxidation and molecular orientation were clarified. For increase in contact resistance, orientation of lubricant molecular acts as important factor was found. The other factors of the lubricant hardly does not effect on contact resistance.

The electrical lubricants have been accepted to reduce friction of contacts and to prevent degradation of contact resistance. However, as the lubricant has an electrical insulation property it seems that application to contact surface is unsuitable for contact resistance. These mechanisms in contact interfaces have not fully understood. In this paper, relationships between contact resistance and contact load were examined with both clean and lubricated surfaces. Orientation of the lubricant molecules was observed by high magnification images of STM and AFM. There was no difference in contact resistance characteristics for both clean and lubricated surfaces in spite of lubricants thickness. The molecules were orientated perpendicular to the surface. This fact turns over an established theory of adsorption of non-polar lubricant to surface.