US Patent 7284991 Flexible scrub ring contact

Multiple small conductive and flexible hollow rings, each of which is made from a pliable material, provide a flexible connection medium for use between a substrate and a microelectronic device package. Each ring is formed to have at least one protuberance on the a ring's exterior surface. The protuberance has an apex or point, which when placed against a surface, will scrub or scrape the surface as the ring is compressed by a force acting on the ring radially. By scrubbing a contact surface with the apex, surface contaminants and layered material that might interfere with electrical signals can be removed.