Rolled copper foil, copper-clad laminate, method for manufacturing copper-clad laminate, method for manufacturing flexible printed wiring board, and method for manufacturing electronic component

Abstract

Provided is a rolled copper foil having a higher flexibility than in the past when made into an FPC. This rolled copper foil contains 99.9 mass% or more of Cu, with the remainder made up by unavoidable impurities, and in the rolled copper foil, the arithmetic mean value of the grain boundary density measured at a total of three points comprising an arbitrary one point and two points equally set away from the one point by 5 mm in the directions perpendicular to the rolling direction, when heat-treated for a heating retention time of 30 minutes at a dryer internal temperature of 260°C is 38.40 mm-1 or less.