Interconnection substrate and method of manufacturing such a substrate

A method of manufacturing an interconnection substrate, comprising:

• providing a thermomechanical support formed by a fiber reinforced organic material crossed by at least one electric interconnection hole;
• forming at least one level of a first interconnection network on a first surface of the thermomechanical support, wherein the first interconnection network is electrically coupled to a first end of the at least one interconnection hole;
• forming at least one level of a second interconnection network on a second surface of the thermomechanical support, wherein the second interconnection network is electrically coupled to a second end of the at least one electric interconnection hole;
• wherein forming each level of the interconnection network comprises:
• forming at least one metal track by plating, forming at least one metal via by pillar plating from said at least one metal track, and then coating said at least one metal track and said at least one metal via in a molding insulating resin layer, said coating being configured to make the at least one metal via flush with a surface of said molding insulating resin layer most distant from the thermomechanical support;
• and
• forming at least one protruding metal track which protrudes from the molding insulating resin layer of a last level of each interconnection network,
• wherein the metal vias are configured to electrically couple together two adjacent levels and/or the last level with the at least one protruding metal track.