| 摘要 |
PURPOSE:To prevent the generation of cracks in a polyimide insulating layer, and the generation of exfoliation between a metal substrate and the polyimide insulating layer due to thermal distortion, by constituting a circuit substrate by interposing a mediation layer containing copper fine-grain component between the metal substrate and the polyimide insulating layer. CONSTITUTION:On a metal substrate 1, an interfacial layer 6 in which copper fine-grain is contained in polyimide is uniformly printed and hardened with a size larger than or equal to the pattern of an insulating layer 2'. Thereon, a multilayer printed interconnection composed of a polyimide insulating layer 2', a conductor layer 3' and via holes 4' is formed. As a result, the polyimide insulating layer 2' is bonded to the mediation layer 6 via the same polyimide. Thermal distortion due to the difference of expansion is reduced by the effect of expansion of copper fine-grain abundant in expandability. By the network effect of dispersed copper fine-grain as inter-resinous substance, stress concentration is reduced, and cracks and exfoliation of the polyimide insulating layer 2' can be prevented. |
