Abstract: A printed wiring board having an interlayer insulation layer and conductive circuits formed on the interlayer insulation layer. The conductive circuits include a first conductive circuit and a second conductive circuit positioned adjacent to each other, and the first and second conductive circuits satisfy a formula, 0.10 T?|W1?W2|?0.73 T, where W1 represents an upper conductive circuit space between the first and second conductive circuits, W2 represents a lower conductive circuit space between the first and second conductive circuits, and T represents a thickness of the first and second conductive circuits.

Abstract: A semiconductor mounting board 80 is prepared by electrically joining an IC chip 70 via an interposer 60 of high rigidity to external pads 41 and internal pads 43, which are formed on the uppermost surface of a build-up layer 30. When the IC chip 70 generates heat, since pads 41 are positioned away from the center, a large shearing stress is applied to the portions at which pads 41 are joined to the interposer 60 in comparison to the portions at which pads 43 are joined to the interposer 60. Here, pads 41 are formed at substantially flat wiring portions and thus when joined to the interposer 60 by means of solder bumps 51, voids and angled portions, at which stress tends to concentrate, are not formed in the interiors of solder bumps 51. The joining reliability is thus high.

Abstract: Each via hole of a printed wiring board is filled with a metal conductor. A distal end of each metal conductor is covered with a diffusing metal layer. The distal end of the metal conductor is pressed against a conductor circuit of another substrate, and the printed wiring boards are bonded together by thermocompression bonding. The metal of the distal end of each metal conductor is diffused into the metal of the conductor circuit so that an alloy layer is formed in an interface. As a result, reliability in the interlayer electrical connection can be improved.

Abstract: Printed circuit board having excellent peel strength and conductance resistance is provided with a substrate, a resin insulating layer formed thereon and roughened at its surface, and a conductor formed thereon, in which at least a portion of the conductor is composed of an eutectic metal layer.

Abstract: A superconductive ceramic wire material composed of rare earth elements, alkali earth metals, copper, and oxygen, which is obtained by mixing a powder containing oxides of the component elements of the superconductive ceramic with a solution containing organic compounds of the component elements, forming the mixture into a wire, and firing the wire in a temperature range from 850.degree. to 949.degree. C. in an oxygen-containing atmosphere.