Abstract: Provided are a wiring base plate and the like including an insulating substrate including a first surface portion including an aluminum oxide-based sintered body and a mullite-based sintered body; and a metallization layer including a second surface portion, the second surface portion containing at least one of a manganese compound and a molybdenum compound and being in contact with the first surface portion of the insulating substrate; wherein the second surface portion of the metallization layer and the first surface portion of the insulating substrate contain at least one of a manganese silicate phase and a magnesium silicate phase.

Abstract: Provided are a wiring base plate and the like including an insulating substrate including a first surface portion including an aluminum oxide-based sintered body and a mullite-based sintered body; and a metallization layer including a second surface portion, the second surface portion containing at least one of a manganese compound and a molybdenum compound and being in contact with the first surface portion of the insulating substrate; wherein the second surface portion of the metallization layer and the first surface portion of the insulating substrate contain at least one of a manganese silicate phase and a magnesium silicate phase.

Abstract: There is provided a ceramic substrate including: a silicon nitride crystal phase containing a plurality of silicon nitride crystals, and grain boundaries between the silicon nitride crystals; and a silicate phase containing magnesium silicate crystals and rare earth silicate crystals, respective maximum particle sizes of the magnesium silicate crystals and the rare earth silicate crystals being smaller than that of the silicon nitride crystals, the silicate phase being positioned in the grain boundaries.

Abstract: There is provided a ceramic substrate including: a silicon nitride crystal phase containing a plurality of silicon nitride crystals, and grain boundaries between the silicon nitride crystals; and a silicate phase containing magnesium silicate crystals and rare earth silicate crystals, respective maximum particle sizes of the magnesium silicate crystals and the rare earth silicate crystals being smaller than that of the silicon nitride crystals, the silicate phase being positioned in the grain boundaries.

Abstract: The invention relates to a circuit board having high density circuit and excellent connection reliability and lamination reliability. A resin fabric cloth (4) is provided by arranging single fibers (4a) or fiber bundles composed of a plurality of single fibers, which single fiber has a linear thermal expansion coefficient smaller than that of silicon, at least in two directions and alternately weaving them. In the board, the resin fabric cloth is covered with a resin portion (5) made of a resin material having a linear thermal expansion coefficient larger than that of silicon.

Abstract: The invention relates to a circuit board having high density circuit and excellent connection reliability and lamination reliability. A resin fabric cloth (4) is provided by arranging single fibers (4a) or fiber bundles composed of a plurality of single fibers, which single fiber has a linear thermal expansion coefficient smaller than that of silicon, at least in two directions and alternately weaving them. In the board, the resin fabric cloth is covered with a resin portion (5) made of a resin material having a linear thermal expansion coefficient larger than that of silicon.

Abstract: Elastomeric block copolymers comprising polyether chains as soft segment in combination with aromatic polyamide chains as hard segment are disclosed, the soft and hard segments being introduced under a sequence control so as to develop excellent physical and mechanical properties. Processes for producing the elastomeric block copolymers are also disclosed.

Abstract: An ester-amide block copolymer of the formula (1): ##STR1## wherein R is an aromatic hydrocarbon group with 6-20 carbon atoms and G is a residue of an aliphatic polyester, an aliphatic polycarbonate, an aliphatic polyethercarbonate or a polyorganosiloxane, and having a weight average molecular weight of 30,000-1,000,000. This copolymer is advantageously prepared by polycondensing an activated acyl lactam-terminated aromatic amide of the formula (2) with a diol of the formula (3) by bulk polymerization in a molten state: ##STR2## wherein R and G are the same as defined above.