Properties of Contact Lubricant under Elevated Temperature for Thin Gold Plated Surface

Terutaka TAMAI  Masahiro YAMAKAWA  Ichiro TAKANO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E100-C   No.2   pp.211-220
Publication Date: 2017/02/01
Online ISSN: 1745-1353
Type of Manuscript: PAPER
Category: Electromechanical Devices and Components
Keyword: 
contact lubricant,  olefin,  connector,  electrical contact,  reflow,  

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Summary: 
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.