New developments in PFPE lubrication: application to tinned electrical contacts

Electrical contacts performances and reliability can be improved by the use of a well-suited lubricant. Much work has been done and is still performed in this field. Different types of lubricants having different compositions and properties have been described. Perfluorinated polyethers (PFPE) are the lubricant class of choice when seeking high thermal and chemical stability, wide operating temperature ranges, and ultimately long lifetime and reliability. It has been shown in previous studies that linear and branched PFPE performed differently according to the contact surface finishes and that depending on the type of wear occurring in the contact different viscosities were beneficial. Indeed a universal lubricant improving the properties of all the various metallic finishes is still something to look forward to. In this paper, we show the first results on the friction and electrical properties of tinned electrical contacts lubricated with a new type of PFPE lubricant, Fomblin® HV25. This new PFPE oil has inherent high-viscosity, ca. 32000cSt (at 20°C), without any thickening agent (e.g. PTFE powder). Reciprocating friction tests were performed with a dedicated instrumented device. Improvements in friction reduction and in electrical behavior as compared PFPE oils with standard viscosities are described.