Sumitomo Metal (smi) Electronics Devices, Inc.

Sumitomo Metal Ceramics Inc.

Narumi China Corporation

Masashi Fukaya

Hideaki Araki

Junzo Fukuta

Susumu Nishigaki

Junzo Fukuda

Shinsuke Yano

Yoshinobu Watanabe

Chiaki Higuchi

Koji Shibata

Osamu Nakagawa

Hiroshi Kawabe

Tomoko Matsuo

A thick-film resistor contains RuO and an SiO &mdash;B O &mdash;K O glass having a composition of 60 wt %&lE;SiO &lE;85 wt %, 15 wt %&lE;B O &lE;40 wt %, 0.1 wt %&lE;K O&lE;10 wt %, and impurity &lE;3 wt %. A ceramic circuit board includes a thick-film resistor printed on it, the thick-film resistor containing RuO and an SiO &mdash;B O &mdash;K O glass having the above composition.

Thick-film resistor and ceramic circuit board

A thick-film resistor paste consists of a first glass powder, a second glass powder, a conductive material powder, and an organic vehicle. A quantity of the first glass powder mixed is larger than a quantity of the second glass powder mixed. The first glass powder contains, in total, 95 percentage by weight or above of CaO of 20 to 26 percentage by weight, SiO.sub.2 of 37 to 59 percentage by weight, Al.sub.2 O.sub.3 of 5 to 13 percentage by weight and B.sub.2 O.sub.3 of 8 to 28 percentage by weight. The second glass powder contains, in total, 85 percentage by weight or above of SiO.sub.2 of 53 to 72 percentage by weight, B.sub.2 O.sub.3 of 20 to 30 percentage by weight and Na.sub.2 O of 1 to 7 percentage by weight. The thermal expansion coefficient of the first glass powder is larger by 0.5.times.10.sup.-6 /deg or above than the thermal expansion coefficient of the second glass powder. A glass transition point of the first glass powder is higher by 30 degrees Celsius or above than a glass transition point of the second glass powder.

Thick-film resistor paste

A ceramic circuit element comprising a ceramic substrate having co-fired resistor and glass overcoat thereon in which the resistor is formed from a resistor paste consisting essentially of RuO.sub.2 powder, glass powder and a vehicle comprising an organic polymer and a solvent, the RuO.sub.2 powder and the glass powder having specific surface areas of 10 to 20 m.sup.2 /g and 4 to 14 m.sup.2 /g, respectively; the glass overcoat is formed from a glass overcoat paste consisting essentially of a glass composition and a vehicle comprising an organic polymer and a solvent, the glass composition having a specific surface area of 2 to 6 m.sup.2 /g; and the ceramic circuit substrate comprises a CaO--Al.sub.2 O.sub.3 --SiO.sub.2 --B.sub.2 O.sub.3 system or MgO--Al.sub.2 O.sub.3 --SiO.sub.2 --B.sub.2 O.sub.3 system glass and alumina. The use of the foregoing resistor and glass overcoat pastes minimizes the bubbles remaining in the resistor and realizes the exertion of resistance performance ensuring excellent weather resistance and stability, even after the resistor is subjected to trimming.

Thick-film paste and ceramic circuit substrate using the same

A ceramic circuit substrate having a resistor deposited on a surface thereof, said ceramic substrate having a coefficient of thermal expansion ranging from 5.0.times.10.sup.-6 /.degree. C. to 7.0.times.10.sup.-6 /.degree. C., the resistor being coated with a glass overcoat and made of 15 to 50% of RuO.sub.2 and 85 to 50% of a CaO--Al.sub.2 O.sub.3 --SiO.sub.2 --B.sub.2 O.sub.3 -system glass, the glass overcoat being made of 60 to 100% of a CaO--Al.sub.2 O.sub.3 --SiO.sub.2 --B.sub.2 O.sub.3 -system glass and up to 40% of alumina, wherein the resistor has a coefficient of thermal expansion greater than that of the glass overcoat. Due to the above specific relationship between the coefficient of thermal expansion of the resistor and that of the overcoat, the resistor is not subject to cracking at the time of trimming and thereafter, and realizes the exertion of resistance performance ensuring excellent weather resistance and stability.

RuO.sub.2 resistor paste, substrate and overcoat system

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 ceramic circuit substrate providing a circuit pattern with a fine line as well as high accuracy for positioning the circuit pattern and a method of producing the ceramic circuit substrate. An alumina layer that is green containing an alumina that is not sintered at a temperature ranging from 800.degree. to 1000.degree. C. is applied on a surface of a ceramic green sheet containing glass and then fired at a temperature ranging from 800.degree. to 1000.degree. C. The ceramic green sheet is sintered into a sintered ceramic substrate. A porous alumina layer is formed on a surface of the sintered ceramic substrate. The glass contained in the sintered ceramic substrate is caused to flow to the inside of the porous alumina layer so that the part of the porous alumina layer filled with the glass is bonded to the sintered ceramic substrate. The part of the porous alumina layer not filled with the glass is removed, wherein the porous alumina layer remaining on the sintered ceramic substrate after the removing has a thickness of 10 .mu.m or less. A paste for forming the circuit pattern is printed on a surface of the part of the porous alumina layer that has been bonded to the sintered ceramic substrate for heating.

Method of producing a 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.

Method of fabricating ceramic circuit substrate

In a multilayer ceramic circuit board comprising a substrate, an insulating layer on the substrate, and a conductive pattern on the insulating layer, an additive of Cr.sub.2 O.sub.3 or MnO.sub.2 is added to the insulating layer to reinforce adhesion between the insulating layer and the conductive pattern. Each of the substrate and the insulating layer is manufactured by firing at a temperature between 800.degree. C. and 1000.degree. C., alumina particles and a glass composition comprising an alumina component. When a total amount of alumina in the substrate is equal to or greater than that in the insulating layer, an amount of Cr.sub.2 O.sub.3 or MnO.sub.2 is restricted to a range between 0.1% and 10.0% by weight, with a difference between the total amounts of alumina falling within a range between 0% and 30% by weight. When the total amount of alumina in the substrate is smaller than that in the insulating layer, the amounts of Cr.sub.2 O.sub.3 and MnO.sub.2 may be between 0.1% and 10.0% by weight and between 0.1% and 15% by weight, respectively. The difference between the total amounts of alumina may be between 0% and 20% by weight.

Multilayer ceramic circuit board fired at a low temperature

Low temperature fired ceramics are produced by a highly improved method, using a specially designed apparatus and the obtained ceramic products are very useful in various applications, such as electronic components, heat resistant articles, tablewares, kitchen utensils or decorative articles because of a combination of superior properties, particularly high heat resistance, high mechanical strength, low thermal expansion and low dielectric constant. In practicing the method, a low firable ceramic material is shaped into a green sheet and then converted to a dense fired ceramic product by rapid firing in an adequate air. In the firing step, the air feed ratio (the ratio of the quantity of feed of air to the theoretical quantity of air required for combustion) is controlled so as to be at least 1.5 thereby the aimed fired products can be obtained in a greatly reduced firing time, without causing deformation or warpage of the ceramics or ignition of the decomposition gases of a binder.

Method for manufacturing low temperature fired ceramics

In an article comprising a ceramic body fired at a comparatively low temperature and a circuit pattern attached to the body, the ceramic body is produced from a preselected composition comprising first powder of alumina and second powder of a vitreous material which comprises any one of MgO-Al.sub.2 O.sub.3 -SiO.sub.2, CaO-MgO-Al.sub.2 O.sub.3 -SiO.sub.2, CaO-Al.sub.2 O.sub.3 -SiO.sub.2 glass, CaO-Al.sub.2 O.sub.3 -SiO.sub.2 -B.sub.2 O.sub.3 glass, MgO-Al.sub.2 O.sub.3 -SiO.sub.2 -B.sub.2 O.sub.3 glass, and CaO-MgO-Al.sub.2 O.sub.3 SiO.sub.2 -B.sub.2 O.sub.3 glass. The ceramic body comprises coexistence of an alumina part, a noncrystallized part, and a crystallized part and exhibits an excellent moisture proof. The circuit pattern comprises an internal conductive pattern of Ag and an external conductive pattern of an alloy of Ag-Pd. A chromium component may be included in the internal and the external conductive patterns. External and internal resistor patterns are placed on and within the ceramic body with a high and a low precision. The internal resistor pattern can be adjusted by the use of a laser beam through a thin film included in the ceramic body.

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Kuwana, Japan

Masashi Fukaya