CONTACT RESISTANCE AND SEPARATION FORCE AT LOW TEMPERATURE OF POLYPHENYL ETHERS ON LUBRICATED CONNECTORS

摘要

Contact lubricants have been used to lower Insertion-withdrawal forces and wear, to reduce the galvanic corrosion and tarnishing of contact finishes, and most recently to prevent fretting corrosion of base metal contacts such as tin and tin-lead platings. Among the most widely used and successful lubricants are the 5-and 6-ring polyphenyl ethers, OS-124* and OS-138*. In some applications, such as in automobiles, connectors may experience low ambient temperatures. It is, therefore, of interest to determine whether such service can be deleterious to connectors that are lubricated with polyphenyl ethers which have relatively high pour points(+5 to +15℃). A study was conducted with typical automotive connectors having gold and tin plated contacts. Mated connectors were cooled and their contact resistances and separation forces determined at 0, -20, and -40℃. It was found that there was (1) no significant change of contact resistance and (2) a lowering of separation force of gold plated contacts that were lubricated with OS-138 at all temperatures compared to control samples at room temperature. On the other hand, tin-lead plated contacts experienced up to a two-fold increase of average contact resistance at -40℃. This change, however, is considered to be acceptable for most applications. The separation force of the tin-lead plated contacts increased by a factor of 2 to 6 compared to the unlubricated or lubricated values at room temperature. This increase is advantageous because it could reduce the tendency to fretting, a deleterious process that is especially serious with contacts having base metal finishes. Overall, polyphenyl ethers are desirable contact lubricants and should be considered for cases where connector function and reliability can be benefitted by them.