Patent ID: 6197433
Filing Date: 2001-03-06
Classification: B21B,C22C,C22F,H05K,Y10S,Y10T

Abstract:
A rolled copper foil for flexible printed circuits characterized in that it contains not more than 10 parts per million by weight of oxygen and has a softening-temperature rise index T defined as T=0.60[Bi]+0.55[Pb]+0.60[Sb]+0.64[Se]+1.36[S]+0.32[As]+0.09[Fe]+0. 02[Ni]+0.76[Te]+0.48[Sn]0.16[Ag]+1.24[P] (each symbol in the brackets representing the concentration in ppm by weight of the element) in the range of 4 to 34, the concentrations of the elements being in the ranges of [Bi]<5, [Pb]<10, [Sb]<5, [Se]<5, [S]<15, [As]<5, [Fe]<20, [Ni]<20, [Te]<[Ag]<50, and [P]<15 (each symbol in the brackets representing the concentration in ppm by weight of the element), and the foil has a thickness in the range of 5 to 50 .mu.m and a half-softening temperature of 120 to 150.degree. C., is capable of continuously retaining a tensile strength of at least 300 N/mm.sup.2 at 30.degree. C., and possesses excellent flex property and adequate softening property.