Production of a sintered ceramic dielectric formed from a green sheet having a uniform microporous structure providing uniform dielectric properties and compressibility for lamination of stacked green sheets into a unitary laminate which may be provided with an internal pattern of electrical conductors extending therein. The structure is obtained by blending the ceramic particulate in a solution of a binder resin miscible in a solvent mixture which is formed from a volatile solvent for the binder resin and a less volatile solvent in which the resin is at most only slightly soluble.
This application is a continuation of abandoned copending application Ser. No. 902,618 filed May 4, 1978, which in turn is a division of its copending application Ser. No. 776,815 filed Mar. 11, 1977, now U.S. Pat. No. 4,104,345 granted Aug. 1, 1978, which in turn is a division of its copending application Ser. No. 589,305 filed June 23, 1975, now U.S. Pat. No. 4,080,414 granted Mar. 21, 1978, which in turn is a continuation-in-part of abandoned application Ser. No. 158,387 filed June 30, 1971.
A ceramic wiring board comprising a silica board having pores of several ten to several hundred .ANG. in diameter amounting to 5 to 20 vol % of the insulating layer, and a process for producing the same, which comprises heat-treating a silicon alkoxide to form a fine silica powder and sintering the fine powder. This board has good mechanical characteristics and a high signal propagation speed.
Ceramic green sheets of controlled microporosity and method of making same have been provided. Controlled microporosity is achieved by including certain ionic species in the ceramic composition, particularly boron, phosphorus and copper oxide.
A multi-layer ceramic wiring board consisting of alternately laminated ceramic insulating substrates and wiring conductor layers in which the inner-layer ceramic insulating substrates contacting the inside layers of signal wiring conductor are made of a ceramic insulator having a relative dielectric constant of 6.0 or below and a relatively low density and the ceramic insulating substrates of other layers are made of a ceramic insulator having a tensile strength of 4 kgf/mm.sup.2 or above and a relatively high density. In preparation of the board, each of the inner-layer ceramic insulating substrates is preferably formed from a green sheet obtained by drying a thin layer of a slurry containing 70 to 90 parts of ceramic filler particles having a particle size of 5 .mu.m or greater and 30 to 10 parts of glass powder while each of other ceramic insulating substrates is preferably formed from a green sheet obtained by drying a thin layer of a slurry containing 70 to 90 parts of ceramic filler particles having a particle size of less than 5 .mu.m and 30 to 10 parts of glass powder.
A wiring body, used for manufacturing a substrate, includes a columnar body, having an axis, made of fired porous inorganic insulator impregnated with an organic insulator; and a large number of metallic fine wires embedded in the columnar body in parallel with the axis while the metallic fine wires are arranged at intervals, wherein a ratio of the inorganic insulator in the columnar body is 50 to 80 volume %, preferably 50 to 60 volume %. A method for manufacturing a wiring body includes the steps of charging a dispersed solution, in which inorganic insulating powder is dispersed, into a container in which a number of metallic fine wires are arranged in parallel with the axis, drying the dispersed solution, and firing inorganic insulating powder so that the porosity of the fired body can be in a range from 20 to 50 volume % so as to form a columnar body; and the steps of impregnating the obtained porous columnar body with uncured organic insulating material, and curing the organic insulating material.
The multi-layer ceramic substrate of this invention includes conductor layers and insulating layers disposed between the conductor layers. The insulating layers include the layers of a sintered body principally composed of mullite and the layers of a sintered body principally composed of alumina. This multi-layer ceramic substrate is produced by laminating the green sheets and sintering the laminate. The green sheets principally composed of mullite and the green sheet principally composed of alumina are prepared, and they are laminated and sintered.
