| 摘要 |
PURPOSE:To obtain a rolled copper foil having diluted density of grain boundary and to obtain a circuit excellent in electrical characteristics by growing the crystal grains of an oxygen-free copper material into huge ones and rolling the copper material successively. CONSTITUTION:An oxygen-free copper material containing <=50ppm oxygen is maintained in an atmosphere of inert gas such as argon at >=800 deg.C, to grow its crystal grains into huge ones. Further, the copper material of huge crystal is rolled; then the crystal is oriented in the rolling direction in proportion to the rolling reduction into a linear crystal, to dilute more the density of grain boundary, thereby reducing remarkably the dielectric effect of the grain boundary. |
