Abstract: To be capable of arbitrarily designing an interconnection shape of a surface layer to thereby promote reliability of connection in laminating layers and making destruction of a semiconductor element difficult to cause in a semiconductor apparatus having interconnections for connecting laminated layers on a surface and a back of a substrate and capable of laminating layers in multiple stages, a semiconductor apparatus is fabricated by a step of mounting a semiconductor element in a recess portion shallower than a thickness of a semiconductor element formed in a surface of a substrate having interconnection patterns connected by a through hole on two of the surface and a back in which a thickness of an interconnection on the surface is made thicker than a thickness of an interconnection on the back with a front thereof disposed on the lower side, a step of sealing the semiconductor element in the recess portion by synthetic resin and a step of grinding the substrate and the semiconductor element up to the inter

Abstract: In an electronic circuit device having such a structure that a plurality of circuit boards are stacked, when the circuit boards are stacked, one ends of metal pieces serving as spacers are joined to one circuit board by solder while the other ends of the metal pieces are joined to the other circuit by conductive adhesive agent, whereby the circuit boards can be easily separated from each other at the connection portion and a rework of the parts sandwiched between the circuit boards can be easily performed.