US Patent 9142333 Differential signal transmission cable and method of making same

A differential signal transmission cable includes two core wires, and a foamed insulation that collectively covers the two core wires by foaming extrusion molding. The foamed insulation is not more than 5% in a dispersion of foaming degree defined below in a cut surface when the cable is cut orthogonally to a longitudinal direction of the cable. In the cut surface, five regions are determined according to a predetermined procedures and a foaming degree (%) of the respective regions is measured. The dispersion of the foaming degree is defined by a difference between a foaming degree (%) in the region with a maximum foaming degree and a foaming degree (%) in the region with a minimum foaming degree.