<p>A conductor path is formed by providing an insulating substrate having a surface region which is formed of an insulating composition. The insulating composition contains an organic polymeric material and at least one metal source. The metal source is a metallic powder and/or an organic compound chemically combining a metal or metals. The surface region of the substrate is selectively heated along a predetermined pattern, thereby decomposing and evaporating the organic polymeric material at the heated portion and welding the metal in the heated portion so as to form a conductor path formed of the metal.</p>
