Connector contact lubricant can reduce mating force and contact wear, the only lubricant can do this. But the real goal is to get more than just friction/wear reduction from the lubricant.
For many of us, the first thing that comes to mind when the word "lubricant" comes up is "smooth things", motor oil, WD40 or silicone grease, none of them are suitable for connectors.
Basic contact completion type
You will recall the two basic contact treatment types used in connectors: precious metals, represented by gold/nickel coatings; non-precious metals, represented by tin coatings, either by plating or by controlled exposure to liquid metal sources (such as Hot air leveling tin (HALT)) to apply. It can be expected that for precious metal and non-precious metal applications, the requirements for lubricants and the benefits obtained from lubricants and therefore lubricant formulations are different.
Gold-plated surfaces are usually used in connectors for more demanding applications, such as connectors that require high performance/reliability or high pin count. High performance/reliability requires low and stable contact resistance, while the high pin count requires low and controlled mating force. In this case, the contact lubricant must provide corrosion protection to improve resistance stability and reduce friction to reduce the mating force of the connector. As the "foundation" of information, the friction coefficients of the gold and tin coatings are in the range of 0.3 and 0.7, respectively. The lubricated connector can be in the range of 0.1, which is the reason for the significant reduction, which is the source of the reduced mating force and reduced wear rate.
In terms of corrosion, the corrosion source of gold-plated or nickel-plated connectors is copper alloy spring materials, which are susceptible to various corrosion mechanisms. The contact lubricant can provide a protective layer on the plating layer near the contact area and the holes in the exposed copper alloy. The small defects in the hole decrease with the increase of the thickness of the plating layer and the small defects in the plating layer may expose the copper at its bottom. Some connectors are pre-plated, which means that the gold on the nickel is applied to the contacts of the plug and socket before the final stamping operation. This will result in a bare copper alloy edge near the mating contact area.
The information is provided by the RF coaxial connector factory.