Abstract: A multi-layer circuit board is disclosed which includes a plurality of AlN ceramic layers stocked and combined as an integrated form and wiring layers interposed at different levels between the AlN ceramic layers. The wiring layers are made of a mixture of tungsten and AlN ceramic particles, the content of the AlN ceramic particles being 0.5 to 2.0 wt. %. A plurality of through-holes are formed in the AlN ceramic layers to interconnect the wiring layers formed at different levels.

Abstract: Between insulative layers (31-37, 41-44), a multilayer substrate comprises at least one dielectric layer (26-29). It is possible to form capacitors (58), resistors (46), and wiring conductors (61, 62) in the substrate. The at least one dielectric layer should be of at least one dielectric composition which has a perovskite structure. Preferably, each insulative layer is of an insulating material which consists essentially of aluminum oxide and lead borosilicate glass. The substrate is convenient in manufacturing a crystal oscillator by mounting a crystal vibrator (71) and a transistor (72) on the principal surface(s). Examples of the dielectric composition are:Pb[(Fe.sub.2/3.W.sub.1/3).sub.0.33 (Fe.sub.1/2.Nb.sub.1/2).sub.0.67 ]O.sub.3,Pb[(Mn.sub.1/3.Nb.sub.2/3).sub.0.01 (Mg.sub.1/2.W.sub.1/2).sub.0.30 (Ni.sub.1/3.Nb.sub.2/3).sub.0.49 Ti.sub.0.20 ]O.sub.3,andPb[(Mg.sub.1/2.W.sub.1/2).sub.0.66 Ti.sub.0.34 ]O.sub.3.

Abstract: A multilayer ceramic substrate with an interlayered capacitor has a large electrostatic capacity and a high flexural strength, such as 1,500 Kg/cm.sup.2 or more, and yet is manufactured at a relatively low firing or sintering temperature. A first ceramic body includes a plurality of laminated first ceramic sheets with a high dielectric constant and with a plurality of internal electrodes sandwiching the respective first ceramic sheets to form capacitors therebetween. A second ceramic body is laminated over one side of the first ceramic body and has a plurality of laminated second ceramic sheets with a low dielectric constant. A plurality of first wiring layers are sandwiched between the second ceramic sheets. A third ceramic body is laminated over the other side of the first ceramic body and has a plurality of laminated third ceramic sheets formed of the same ceramic material that is used to make the second ceramic sheets. The second and third ceramic bodies are thicker than the first ceramic body.

Abstract: A multilayer glass-ceramic substrate comprises insulator layers of a composition consisting essentially of, when components are expressed as oxides in percent by weight, 40-60 percent of aluminum oxide, 1-40 percent of lead oxide, 1-30 percent of boron oxide, 2-40 percent of silicon dioxide, 0.01-25 percent of at least one oxide of chemical element(s) of Group II of the periodic table, and 0.01-10 percent of at least one oxide of Group IV element(s) except carbon, silicon, and lead. Each insulator layer may be only from 190 microns down to 10 microns thick. The substrate has a flexural strength of 2,100 kg/cm.sup.2 or more. Preferably, the Group II element(s) is magnesium, calcium, strontium, barium, and/or zinc. The Group IV element(s) is zirconium, titanium, germanium, and/or tin. When the percentages are 40-60 for aluminum oxide, 4.1-16.6 for lead oxide, 1.0-10.0 for boron oxide, 14.0-39.1 for silicon dioxide, 0.1-4.8 for magnesium oxide, 2.0-10.0 for calcium oxide, 0.05-3.0 for barium oxide, 0.01-3.