a copper - clad aluminum composite wire has a core that is made of an al - mg alloy and circumferentially clad with copper or a copper alloy . the aluminum alloy is composed of 1 . 5 to 10 . 0 percent by weight of mg , additives such as cr and mn , ordinary impurities , and aluminum whose content is such as to form the rest of the alloy composition . the copper or the copper alloy forms 20 to 40 % of the cross - sectional area of the copper - clad aluminum composite wire . such core material is drawn to reduce the cross - sectional area by 20 % or more using a die whose half angle α is from 15 to 30 degrees to obtain an cladding wire ; the cladding wire is further drawn to reduce the cross - sectional area by 70 % or more using a drawing die whose half angle α is from 4 to 15 degrees at least once ; and the thus drawn wire is subjected to annealing at temperatures from 200 ° to 400 ° c . for from one minute to 24 hours .