Multi-layer circuit board and method of manufacturing same

摘要

An inner layer circuit board with a convex inner layer circuit pattern having a predetermined thickness, a prepreg sheet having conductive material disposed in a plurality of through-holes and metallic foil are laminated to a substrate, and the laminated board is heated under pressures. After that, a laminated circuit pattern is formed by machining the metallic foil. In such multi-layer circuit board, a smoothing layer is disposed on a concave portion where no inner layer circuit pattern of the inner layer circuit board is formed. In this way, the conductive materials disposed in a plurality of through-holes are uniformly compressed. As a result, the connection resistance between the inner circuit pattern and the laminated circuit pattern becomes stabilized.