Pressure electrical contact improved by carbon black paste

Pressure and pressureless electrical contacts were evaluated by measuring the contact electrical resistivity between copper mating surfaces. Pressure electrical contacts with a contact resistivity of 2×10−5 Ω·cm2 have been attained using a carbon black paste of a thickness of less than 25 μm as the interface material. In contrast, a pressureless contact with silver paint as the interface material exhibits a higher resistivity of 3×10−5 Ω·cm2 or above. A pressureless contact with colloidal graphite as the interface material exhibits the same high contact resistivity (1×10−4 Ω·cm2) as a pressure contact without any interface material. On the other hand, pressureless contacts involving solder and silver epoxy exhibit lower contact resistivity than carbon black pressure contacts.