Stress Relaxation Measurements of Aluminium Conductors in Insulation Displacement Connectors (IDC´S) and Related Effects on Contact Resistance

Aluminum cables have been in use for some years in the United Kingdom (UK) telephone network. The successful jointing of these cables has necessitated the continuous development of connection systems primarily because of the higher stress relaxation rate of aluminum in comparison to copper. The measurement of stress relaxation of aluminum in two types of insulation displacement connector (IDC) is described: one type with a tin-plated connecting element and the other with an indiumplated one. Experimental methods are described for measuring small amounts of stress relaxation in situ and relationships are discussed for the stress analysis of the joint. In summary the results show that although the stress relaxation rates for the two designs are similar, indium plating enrares a low contact resistance to much lower values of contact stress.