Abstract: A modular multilayer interwiring structure comprising a plurality of relatively small parts which are produced separately as `sub-units` (1). Each individual layer of the final structure is formed by joining a respective set of unit parts in one plane. The whole multilayer structure is then built by stacking these layers, preferably so that the units of one layer are not vertically aligned with the units of an adjacent layer. Each unit part includes at least one layer of conductive material (8, 9) on its front and/or rearside. These conductive layers may be individually patterned into diverse interconnection lines (5). Throughconnections (6) extending from the frontside to the backside of the units are provided using a desired set or a standardized array of via holes or openings filled with conductive material. By connecting desired throughconnections to the respective conduction lines, each unit may form an individual part of a more complex multilayer interwiring structure.