Sumitomo Metal Ceramics Inc.

Murata Manufacturing Co., Ltd.

Sumitomo Metal (smi) Electronics Devices, Inc.

Sumitomo Metal Electronics Devices Inc.

Sumitomo Metal Industries, Inc.

Sumotomo Metal Electronics Devices, Inc.

Junzo Fukuta

Masashi Fukaya

Hideaki Araki

Satoru Adachi

Satoshi Nakano

Katsuhiko Naka

Katsuya Kawakami

Yoshio Mizuno

Toshihiro Nakai

Yoshiaki Yamade

Nozomi Tanifuji

Masaya Hashimoto

Koji Shibata

Hidenori Kataura

Seigo Ooiwa

A method of fabricating a multilayer ceramic substrate includes stacking one or a plurality of unfired ceramic greensheets on one or both sides of a previously fired ceramic substrate, thereby forming a stack, each unfired ceramic greensheet having a firing temperature substantially equal to or lower than a firing temperature of the previously fired ceramic substrate, stacking a restricting greensheet on the unfired ceramic greensheet composing an outermost layer of the stack, the restricting greensheet having a higher firing temperature than each unfired ceramic greensheet, firing the stack at the firing temperature of the unfired ceramic green sheets with or without pressure applied via the restricting greensheet while the stack is under restriction by the restricting greensheet, thereby integrating the stack, and eliminating remainders of the restricting greensheet after the firing step.

Method of fabricating multilayer ceramic substrate

After a resistor and/or a capacitor are simultaneously fired on a fired ceramic core substrate to be fired, the fired resistor and/or the fired capacitor is trimmed so that the resistance and the capacitance are adjusted. Thereafter, an after-lamination green sheet is laminated onto the ceramic core substrate and the produced after-lamination substrate is fired at a temperature which is lower than the sintering temperature of the resistor and the dielectric. Thus, the sintered resistor and dielectric can be prevented from being softened and melted when the after-lamination substrate is fired. Moreover, the resistance and the capacitance accurately adjusted by trimming before the after-lamination substrate is fired are not changed by the firing.

Method of producing ceramic multilayer substrate

A method of fabricating a ceramic multilayer substrate includes steps of laminating a plurality of green sheets including an inside green sheet formed with a conductor pattern and pressing a laminate of green sheets under a predetermined pressure together with sheet restricting members applied to opposite surfaces of the laminate respectively, thereby bonding the laminate and sheet restricting members together, each sheet restricting member having a smaller percent change in thickness than the green sheets during the bonding and a higher firing temperature than the green sheets, firing a bonded assemblage of the green sheets and sheet restricting members at a firing temperature of the green sheets, and removing the sheet restricting members from the opposite surfaces of a fired body.

Method of fabricating ceramic multilayer substrate

A low-temperature fired ceramic circuit substrate fired at a temperature ranging between 800.degree. and 1,000.degree. C. includes a plurality of insulating layers each formed of a low-temperature fired ceramic, an Ag conductor layer formed internally of the substrate, an Au conductor layer formed on a surface of the substrate, and an Ag-Pd layer formed between the Ag and the Au conductor layers, the Ag-Pd layer being composed of 100 parts metal composition consisting of 70 to 95 parts Ag and 5 to 30 part Pd by weight, and 2 to 10 parts lead borosilicate glass by weight. As the result of the above composition of the ceramic circuit substrate, its fabrication process can be simplified, and a defect rate in a connection between the Ag and Au layers after repeated firing is rendered approximately zero, which ensures high reliability for the connection.

Low-temperature fired ceramic circuit substrate and thick-film paste for

A low-temperature fired ceramic circuit substrate includes a plurality of laminated insulating layers each formed of a low-temperature fired ceramic fired at a temperature ranging between 800 and 1,000.degree. C., an inside layer wiring conductor formed of a conductive material of Ag system which is mainly composed of Ag, the inside layer wiring conductor being disposed in the inside insulating layer, a surface layer wiring conductor formed of a conductive material of Au system which is mainly composed of Au, the surface layer wiring conductor being disposed on the surface insulating layer, and an intermediate metal layer formed of a thick film paste of a conductive material of Au/Ag system which is mainly composed of Au/Ag, the intermediate metal layer being interposed between the inside layer wiring conductor and the surface layer wiring conductor.

Low-temperature fired ceramic circuit substrate with improved Ag-Au

In a method of manufacturing a multilayered ceramic substrate, a capacitor layer is formed on a green sheet of a low temperature co-firable ceramic by means of printing. The green sheet with the capacitor layer and a plurality of other green sheets are laminated together into a substrate laminate. Two release green sheets of alumina system each unsintered below 1,000.degree. C. are further laminated to the top and the bottom of the substrate laminate respectively. The obtained laminate is fired at a temperature ranging between 800.degree. and 1,000.degree. C. under pressure ranging between 2 and 20 kgf/cm.sup.2. The release green sheets adherent to the side surfaces of the substrate are removed after the firing. Subsequently, a wiring pattern is printed on the substrate, which is then fired at a temperature ranging between 800.degree. and 1,000.degree. C.

Method of manufacturing multilayered ceramic substrate

A silver-based electrically conductive paste used for printing on green sheets of a low-temperature firable ceramic comprising a CaO--Al.sub.2 O.sub.3 --SiO.sub.2 --B.sub.2 O.sub.3 --system glass and Al.sub.2 O.sub.3, wherein a silver-based powder in the conductive paste has a specific surface area in the range of 0.1 to 0.5 m.sup.2 /g and the formation of a scratch begins when the value measured with a grind gage for the paste containing an organic resin and an organic solvent is in the range of 30 to 10 .mu.m. The silver-based conductive paste makes it possible to co-fire with a low-temperature firable ceramic substrate without causing the warping of the substrate and, therefore, is very useful for the formation of wiring conductors of internal layers of a multilayer circuit substrate of the low-temperature firable ceramic.

Silver-based conductive paste and multilayer ceramic circuit substrate

A conductive paste for filling through holes for the interlayer electrical connection in a low-temperature firable ceramic circuit substrate to be fired at 800.degree. to 1,000.degree. C., which comprises a) 100 parts by weight of flaky and/or spherical silver-based powder particles; b) 0.1 to 2.0 parts by weight of b.sub.1) Sb.sub.2 O.sub.3 or a substance which is converted into Sb.sub.2 O.sub.3 by the firing and the amount of which is given in terms of Sb.sub.2 O.sub.3 and/or b.sub.2) Rh powder; and c) at least 3 parts by weight of 2-tetradecanol. The conductive paste has excellent printing properties and homogeneity because the viscosity change thereof is only small when it is printed into through holes of a ceramic circuit substrate and the crack formation after the firing is slight. Thus, the conductive paste is effective for efficient production of a ceramic circuit substrate of a high density wiring. The conductive paste may contain at least one organic resin selected from the group consisting of ethylcellulose, hydroxyethylcellulose and an acrylic resin.

Conductive paste containing 2-tetradecanol and ceramic circuit substrate

A low-temperature fired ceramic circuit substrate fired at a temperature ranging between 800.degree. and 1,000.degree. C. includes a plurality of insulating layers each formed of a low-temperature fired ceramic, an Ag conductor layer formed internally of the substrate, an Au conductor layer formed on a surface of the substrate, and an Ag--Pd layer formed between the Ag and the Au conductor layers, the Ag--Pd layer being composed of 100 parts metal composition consisting of 70 to 95 parts Ag and 5 to 30 part Pd by weight, and 2 to 10 parts lead borosilicate glass by weight. As the result of the above composition of the ceramic circuit substrate, its fabrication process can be simplified, and a defect rate in a connection between the Ag and Au layers after repeated firing is rendered approximately zero, which ensures high reliability for the connection.

A ceramic circuit board comprises a ceramic substrate having a glaze film formed thereon, the glaze film being overlaid with a functional thin film such as a ferromagnetic film serving as a magnetic sensor, for example. The ceramic substrate is made of a low-firing ceramic material such as a glass ceramic material which can be sintered at a temperature below 1000.degree. C. by co-firing with the glaze film. Preferably, the ceramic substrate has a recess on its top surface, and the glaze film is embedded in the recess such that the difference in level between the ceramic substrate and the glaze film is 20 .mu.m or less. The ceramic circuit board can be produced by preparing a plurality of ceramic green sheets from a low-firing ceramic material, laminating the ceramic green sheets after a through-hole or indentation is formed in the uppermost sheet, thereby forming a multilayer ceramic green substrate having a recess on its top surface, filling the recess with a glaze-forming glass material to such a height that the difference in level between the ceramic substrate and the glaze film formed after firing is 20 .mu.m or less, and co-firing the ceramic green substrate and the glaze-forming glass material at a temperature below 1000.degree. C.

Ceramic circuit board and process for producing same

A process for producing circuit substrate is prepared by preparing at least one ceramic greensheet containing glass and sinterable at a low temperature for forming the circuit substrate, and at least one unsintered transfer sheet unsinterable at a sintering temperature of the ceramic greensheet, printing a wiring pattern on the unsintered transfer sheet, stacking the unsintered transfer sheet on the ceramic greensheet to form a laminated body and thermocompressing the laminated body to form a compressed body, firing the compressed body at a sintering temperature of the ceramic greensheet to form a ceramic substrate, thereby preparing a fired body by transferring the wiring pattern on the unsintered transfer sheet to the ceramic substrate, and removing the unsintered transfer sheet from the fired body to prepare a circuit substrate.

Process for producing a circuit substrate

A ceramic circuit substrate is fabricated by preparing ceramic greensheets for the fabrication of the ceramic circuit substrate, and unsintered ceramic sheets unsinterable at a sintering temperature of said ceramic greensheets, forming via holes in said ceramic greensheets and filling the via holes with via hole conductor paste, printing conductive patterns on the ceramic greensheets, stacking and laminating the ceramic greensheets to prepare a laminated body, placing said unsintered ceramic sheets on the uppermost layer and-on the lowermost layer of the laminated body, bonding the sheets together by thermocompression to prepare a compressed body, firing the compressed body at the sintering temperature of ceramic greensheets, and removing the unsintered ceramic greensheets, wherein said via hole conductors are only in connection with the conductive patterns at the upper and/or lower ends of each via hole conductor.

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Nagoya, Japan

Junzo Fukuta