Differential transmission cable and method of manufacturing the same

摘要

A differential transmission cable includes at least one pair of inner conductors arranged in parallel and extending parallel to each other, and a foamed insulating material formed on the inner conductors by a collective extrusion coating and molding of a resin material by using a chemical foaming method and have a variation of foaming degree of not more than 1%. The variation of foaming degree is defined as a difference between a maximum value and a minimum value among foaming degrees (%) of the foamed insulating material at 20 positions at intervals of 50 cm in a longitudinal direction in an arbitrary part of 10 m cut out from the differential transmission cable.

主权项

1. A method of manufacturing a differential transmission cable, the method comprising:
providing at least one pair of inner conductors arranged side by side and extending parallel to each other; accumulating or circulating a temperature gradient alleviating liquid of 95 degrees C. to 130 degrees C. in or through a screw of a single screw extruder so as to planarize a temperature gradient of a resin material to which a chemical foaming agent is added; and extrusion-coating and molding the foamed resin material around the inner conductors together, to thereby arrange a foamed insulating material around the inner conductors, wherein a variation of a degree of foaming of the foamed insulating material is within 1%.