Micro Asperity Contact Mechanics in Millimeter Wave Test Socket Interfaces
Mechanical preload across socket micro asperities defines insertion loss stability and constriction resistance in millimeter wave automated device testing.
Wipe Displacement
Meaning
Lateral sliding motion that occurs between a connector pin and its mating pad during the insertion process. Wipe displacement is designed to mechanically scrape away surface oxides and contaminants from the contact area. This action ensures a clean metal to metal interface for low resistance electrical flow.
Cleaning Mechanism
Friction from the movement breaks through the brittle layers that form on metals like tin or nickel. The leading edge of the pin pushes the debris aside and reveals fresh metal underneath. This action is especially important for connectors that sit idle for long periods in corrosive environments.
Plating Wear
Repeated sliding removes a small amount of the surface finish with every cycle. If the wipe displacement is too long or the force is too high, the protective plating can be completely worn through. Engineers must balance the need for cleaning against the requirement for a high number of mating cycles.
Tests are conducted to find the maximum displacement that maintains the plating integrity.
Contact Geometry
Shape of the pin tip determines how effectively it can scrape the surface. A sharp or pointed tip provides high local pressure for better cleaning but increases the rate of wear. Rounded tips are gentler on the plating but may require more force to achieve the same level of oxide penetration.