Impact of Aging on PIM and DC Resistance of Fabric-over-Foam Metallic Contacts

In this paper the impact of aging on the level of passive intermodulation (PIM) and DC resistance of fabric-over-foam metallic contacts is presented. These contacts are widely used to maintain metallic connections between modules and chassis in electronic devices. The PIM caused by the loose metallic contact of these materials mainly affects a receiver’s RF sensitivity in mobile devices. This aging test under elevated temperature and relative humidity conditions offers an experiment-based approach with respect to various metallic contact cases. Energy dispersive spectroscopy and scanning electron microscopy are used to characterize the change in material composition and the contact surface throughout the aging. The experimental environmental effects showed the aging on the generated PIM level to have little to no impact from weakened adhesive contact and an increase in lowest PIM floor. Also, an increase in DC resistance level of these metallic contact materials was observed due to an oxide growth on the fabric-over-foam surface.