Process for producing circuit board

A process for producing a circuit board, comprising the steps of:

• detachably stacking three-layer metal laminates on the front surface and the back surface of a supporting substrate such that a first metal layer of each of the three-layer metal laminate is in contact with the corresponding surface of the supporting substrate, the three-layer metal laminates each including the first metal layer, a second metal layer that is not etched by an etching solution for the first metal layer, and a third metal layer composed of the same metal material as that of the first metal layer laminated in that order;
• etching the third metal layers of the three-layer metal laminates by photolithography into predetermined interconnection patterns;
• forming laminates on the interconnection patterns by a buildup method, the laminate including interconnection patterns with insulating layers provided therebetween, the interconnection patterns being electrically connected to each other;
• separating the first metal layers from the supporting substrate to detach the laminates;
• removing the first metal layers of the three-layer metal laminates by etching using the second metal layers as barrier layers;
• and
• removing the exposed second metal layers by etching.