JP2018006774A - Ceramic circuit board, ceramic circuit board with radiator, and method of manufacturing ceramic circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact ceramic circuit board high in insulation reliability by solving such a problem that a reduced size of a ceramic circuit board is difficult since it is necessary to ensure a sufficient creepage distance for insulation between circuit wiring applied with a high voltage.SOLUTION: A ceramic circuit board 1 of the present invention includes a ceramic substrate 2 having a plurality of wiring arrangement portions 9a, 9b, and a plurality of metal wiring 3a, 3b disposed to the ceramic substrate 2 and connecting an electronic component. The ceramic substrate 2 includes an insulating part 8a with a step, between the two metal wiring 3a, 3b adjacent to each other. The insulating part 8a has a first side face 11a, a first top face 13a, a second side face 11b, a bottom face 12a, a third side face 11c, a second top face 13b, and a fourth side face 11d. The creepage distance between the two metal wiring 3a, 3b adjacent to each other through the insulating part 8a is equal to or more than a creepage distance required for insulation.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a ceramic circuit board having a metal circuit pattern for mounting electronic components.

  In recent years, a semiconductor element called a power device is used in a control unit that controls an electric vehicle, a train, wind power generation, solar power generation, a machine tool, and the like. A plurality of semiconductor elements mounted on a circuit board into a single package, or a plurality of semiconductor elements and additional circuits such as a protection circuit and a control circuit are mounted on a circuit board into a single package. This is called a power module. Because power modules handle high voltages up to thousands of volts and large currents up to thousands of amperes, and the amount of heat generated by the elements is large, circuit boards are required to have high withstand voltage, high heat resistance, and high thermal conductivity. The Therefore, ceramics is used as the material for the circuit board.

  Thus, the semiconductor element which handles a high voltage and a large current is mounted on a ceramic circuit board with a heat sink described in Patent Document 1, for example. The ceramic circuit board with a heat sink disclosed in Patent Document 1 includes a ceramic substrate, a heat sink formed of an AlSiC-based composite material, and first and second layers formed of an AlSiC-based composite material laminated and bonded to both surfaces of the ceramic substrate. An aluminum plate. In this ceramic circuit board, the circuit pattern is formed by etching the second aluminum plate. A semiconductor chip, which is a chip-like semiconductor element, is mounted on the circuit pattern, and heat generated from the semiconductor chip or the like is dissipated from the surface of the heat sink fin of the heat sink via the ceramic substrate and the first aluminum plate. It is like that.

JP-A-10-65075 (0004 stage, 0009 stage, FIG. 1)

  In the ceramic circuit board with a heat sink shown in Patent Document 1, an aluminum plate is bonded to the ceramic substrate with solder, and the aluminum plate is etched to form a circuit pattern. In the circuit pattern structure formed in this way, it is necessary to secure a sufficient creepage distance for insulation between circuit wirings to which a high voltage is applied, and it is difficult to reduce the size of the ceramic circuit board. In addition, the ceramic circuit board with a heat sink shown in Patent Document 1 may lead to dielectric breakdown of a semiconductor element mounted on a circuit pattern if the removal of aluminum scrap after etching is insufficient.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a ceramic circuit board that is small and has high insulation reliability.

  The ceramic circuit board of the present invention includes a ceramic substrate having a plurality of wiring arrangement portions, and a plurality of metal wirings arranged on the ceramic substrate and connecting electronic components, and the ceramic substrate includes two adjacent metal wirings. An insulating part having a step is provided between them. The insulating portion includes a bottom surface, a first top surface located on one metal wiring side of two adjacent metal wirings, and a second top surface located on the other metal wiring side among the two adjacent metal wirings. , A first side surface located between the wiring arrangement portion provided with one metal wiring and the first upper surface, a second side surface located between the first upper surface and the bottom surface, a bottom surface and the first A third side surface located between the two upper surfaces, and a fourth side surface located between the wiring arrangement portion provided with the other metal wiring and the second upper surface, and adjacent two Each height of the wiring arrangement portion where the metal wiring is arranged is higher than the height of the bottom surface and lower than the height of the first upper surface and the second upper surface, and from one metal wiring to the first side surface. Distance and width of first top surface, bottom surface, and front second top surface, and first side surface, second side surface, third side surface And the height of the fourth aspect, as well as the sum of the distances from the other metal wire to the fourth aspect is creeping distance than is necessary for the insulation between the two adjacent metal wires.

  According to the ceramic circuit board of the present invention, an insulating portion having a step is provided between two adjacent metal wirings, and the insulating portion is a first side surface, a first top surface, a second side surface, a bottom surface, a third surface. A creeping distance between two adjacent metal wirings through an insulating portion is required for insulation between the two metal wirings. Therefore, the creepage distance between the circuit wirings can be increased without increasing the overall distance, and a ceramic circuit board with high insulation reliability can be obtained.

It is a cross-sectional schematic diagram of the ceramic circuit board with a heat radiator by Embodiment 1 of this invention. It is a cross-sectional schematic diagram of the ceramic substrate of FIG. It is a cross-sectional schematic diagram of the ceramic circuit board by Embodiment 1 of this invention. It is a cross-sectional schematic diagram of the ceramic circuit board by Embodiment 2 of this invention. It is a cross-sectional schematic diagram of the 1st ceramic circuit board by Embodiment 3 of this invention. It is a cross-sectional schematic diagram of the 2nd ceramic circuit board by Embodiment 3 of this invention. It is a cross-sectional schematic diagram of the 3rd ceramic circuit board by Embodiment 3 of this invention. It is a figure which shows the manufacturing process of the ceramic circuit board by Embodiment 4 of this invention. It is a figure which shows the principal part of the ceramic circuit board by Embodiment 4 of this invention.

Embodiment 1 FIG.
FIG. 1 is a schematic cross-sectional view of a ceramic circuit board with a radiator according to Embodiment 1 of the present invention, and FIG. 2 is a schematic cross-sectional view of the ceramic substrate of FIG. FIG. 3 is a schematic cross-sectional view of the ceramic circuit board according to Embodiment 1 of the present invention. The radiator-equipped ceramic circuit board 20 includes the ceramic circuit board 1, the metal base plate 5, and the heat sink 16. The ceramic circuit board 1 includes metal wirings 3a, 3b, 3c, and 3d that constitute a circuit pattern that connects the ceramic substrate 2 and an electronic component (not shown) such as a semiconductor chip. The ceramic substrate 2 is provided with wiring arrangement portions 9a, 9b, 9c, and 9d for arranging metal wirings 3a, 3b, 3c, and 3d on the surface side on which electronic components are mounted. The metal wirings 3a, 3b, 3c, and 3d are joined to the wiring arrangement portions 9a, 9b, 9c, and 9d. A metal base plate 5 is bonded to the back side of the ceramic substrate 2. A heat sink 16 is attached to the other surface of the metal base plate 5, that is, the surface opposite to the surface bonded to the ceramic substrate 2. The reference numeral of the metal wiring is 3 as a whole, and 3a to 3d are used in the case of distinction. The reference numeral 9 of the wiring arrangement portion is generally used, and 9a to 9d are used in the case of distinguishing the description.

  The ceramic substrate 2 of the present invention is characterized in that an insulating portion 4 having a step for insulating between adjacent metal wirings 3 is formed on the surface side on which electronic components are mounted. Many shapes can be considered for the insulating part 4 having a step. In the first embodiment, an example in which the insulating portion 4 has a convex shape (a kind of protrusion shape) will be described. The ceramic substrate 2 shown in FIGS. 1 and 2 is an example provided with three insulating portions 4a, 4b and 4c and two outer peripheral portions 10a and 10b. The reference numerals of the convex insulating portions are 4 as a whole, and 4a to 4c are used when they are distinguished from each other. As shown in FIG. 3, the convex insulating portion 4 includes two side surfaces 11 a and 11 b and an upper surface 13. The insulating part 4 is provided between the adjacent wiring arrangement part 9a and the wiring arrangement part 9b, and the height from the wiring arrangement part 9a, 9b to the upper surface 13 of the insulating part 4, that is, the height of the side surfaces 11a, 11b. There is a corresponding step. The insulating portion 4 can increase the creeping distance between the adjacent metal wiring 3a and the metal wiring 3b. The ceramic circuit board 1 of the present invention can increase the creeping distance between the metal wirings 3 which are adjacent circuit wirings without increasing the whole size by the insulating part 4 of the ceramic substrate 2 and increase the insulation reliability. be able to.

  The total height of the two side surfaces 11a and 11b in the insulating portion 4 is an increased creepage distance from the adjacent metal wiring 3a to the metal wiring 3b. The creepage distance when there is no insulating portion 4 is the sum of the distance from the metal wiring 3a to the side surface 11a, the width of the upper surface 13 in the direction sandwiched between adjacent metal wirings, and the distance from the metal wiring 3b to the side surface 11b. It is. The creeping distance when the insulating part 4 is present is added to the creeping distance when the insulating part 4 is not present. In order to increase the creeping distance between adjacent wirings without increasing the size of the ceramic substrate 2, the height of the insulating portion 4, that is, the step of the insulating portion 4 may be increased.

  As shown in FIG. 2, the insulating portion 4a includes two side surfaces 11a and 11b and an upper surface 13a. The insulating portion 4b includes two side surfaces 11c and 11d and an upper surface 13b, and the insulating portion 4c includes two side surfaces 11e and 11f and an upper surface 13c. The heights of the three insulating portions 4a, 4b, and 4c are all the distance d2. The thickness of the ceramic substrate 2 is a distance d1, and the four wiring placement portions 9a, 9b, 9c, 9d are formed at a depth of a distance d2 from the surface of the ceramic substrate 2. The reference numeral of the outer peripheral portion is 10 as a whole, and 10a and 10b are used in the case of distinction. 11 is generally used as the reference numeral of the side surface, and 11a to 11j are used in the case of distinction. The reference numeral 13 is generally used for the upper surface, and 13a to 13c are used in the case of distinction.

  In a structure in which the height of the surface of the wiring placement portion 9 on which the metal wiring 3 is placed is lower than the height of the insulating portion 4 located around the wiring placement portion 9 with respect to the back surface of the ceramic substrate 2, the metal wiring 3 When adhering by brazing, the side surface 11 of the insulating portion 4 formed on the ceramic substrate 2 serves as a wall, and leakage of the brazing material (not shown) can be prevented.

  As a method for forming the ceramic structure which is the basis of the ceramic substrate 2, a raw material granule made by a spray dryer is compacted by a mechanical press, and the raw material granule is filled in an elastic mold such as rubber. CIP molding that is molded under hydrostatic pressure in water, cast molding in which the raw material is slurried and cast into a mold made of water-absorbing porous material such as gypsum, and the raw material is dispersed and heated in a thermoplastic resin, etc. Injection molding to be poured into a mold, extrusion molding in which raw materials are dispersed in a plastic resin and vacuum-kneaded in a clay form is extruded in a uniaxial direction via a die member, and the raw material is made into a doctor blade by slurrying. And tape molding which is applied to a carrier sheet and solidified by drying. Injection molding is suitable as a molding method in which a large number of ceramic structures having insulating portions 4 can be manufactured relatively easily. In the first embodiment, a method for manufacturing a ceramic substrate 2 using injection molding will be described.

  As the material of the ceramic substrate 2, a ceramic material having high insulation resistance, high thermal conductivity, high strength, high heat resistance, and low thermal expansion is used. This material desirably contains at least one ceramic material of aluminum nitride, silicon nitride, aluminum oxide, zirconium oxide, silicon oxide, and silicon carbide. For aluminum nitride, it is desirable to use yttrium oxide as a sintering aid, and calcium oxide and magnesium oxide may be used. Thermoplastic resins, waxes, lubricants, plasticizers and the like are used for the organic binder used in the injection molding.

  Thermoplastic resins for organic binders include polystyrene, polybutyl methacrylate, polyoxymethylene, polypropylene, styrene / acrylic copolymer, amorphous polyolefin, ethylene / vinyl acetate copolymer, ethylene / methyl acrylate copolymer, ethylene ethyl acrylate A polymer compound consisting of at least one selected from a copolymer, an ethylene / butyl acrylate copolymer, and an ethylene glycidyl methacrylate copolymer is used. The organic binder wax, lubricant, and plasticizer are one type selected from fatty acid ester, fatty acid amide, higher fatty acid, phthalic acid ester, adipic acid ester, paraffin wax, microcrystalline wax, urethanized wax, and maleic anhydride modified wax. The organic compound consisting of the above is used. Particularly for thermoplastic resins, polystyrene, butyl methacrylate, ethylene / vinyl acetate copolymer or ethylene / butyl acrylate copolymer are desirable, and for wax, plasticizer and lubricant, paraffin wax, fatty acid amide or phthalic acid ester is desirable.

  The addition amount of the organic binder is suitably 35 to 60 vol% with respect to the ceramic material. It is desirable that the ceramic material and the thermoplastic resin, wax, lubricant, and plasticizer are kneaded with a kneader to pelletize the material to a particle size of about 5 mm in advance.

  The ceramic substrate 2 is, for example, 60 mm, 55 mm, and 2 mm in length, width, and thickness, respectively. The gate in the injection mold was a fin gate, and was arranged so that the material was injected from the lateral direction of the ceramic substrate 2. The height of the insulating part 4 was 0.5 mm, and the width of the upper surface 13 of the insulating part 4 was 1 mm. In order to form the insulating portion 4, a nest was placed in the injection mold. Since the insert can be exchanged and rearranged according to the shape of the insulating portion 4, a plurality of insulating portions 4 and various shapes of insulating portions 4 can be formed with one mold. When the shape of the insulating portion 4 is changed, it is not necessary to newly manufacture a mold, and therefore the mold cost can be reduced.

  The ceramic substrate injection molding process is performed as follows. As the injection molding machine, a 50t molding machine was used. The pelletized raw material is melted in a heating cylinder, injected from a nozzle into a heated injection mold, and then cooled and solidified. The heating temperature of the cylinder was 150 ° C., and the mold temperature during molding was 35-40 ° C. The injection speed of the material into the injection mold was 20 to 180 mm / s, and the holding pressure was 20 to 40 MPa.

  In the ceramic substrate degreasing step, the ceramic substrate 2 formed by injection molding is degreased. Degreasing is a process of desorbing an organic binder contained in a material by thermal decomposition or oxidation. It is desirable that the temperature in the furnace is 500 ° C. or higher in air or in a nitrogen atmosphere. During degreasing, the molded body shrinks, so that cracking may occur due to rapid heating and rapid cooling. In this example, the heating rate was 10 ° C./hr. Cooling was naturally cooled in the furnace.

  In the ceramic substrate firing step, the ceramic substrate 2 is fired in a gas atmosphere such as air, nitrogen, argon or the like according to the ceramic material to be used, and the firing temperature is adjusted so that no continuous pores remain inside. If continuous pores remain in the interior, the thermal conductivity of the ceramic substrate deteriorates and a sufficient cooling effect cannot be obtained.

  In the circuit pattern forming step, a circuit pattern having a plurality of metal wirings 3 is formed according to the insulating portion 4 of the ceramic substrate 2. The circuit pattern is formed by brazing the metal wiring 3 previously processed into a predetermined plate shape by machining or the like to the ceramic substrate 2. An Al—Si brazing material (not shown) is printed on the ceramic substrate 2 in a predetermined pattern shape using a screen printer. After drying at 80 ° C., the metal wiring 3 processed into a predetermined pattern shape is placed thereon and heated at 600 to 630 ° C. in a vacuum furnace, whereby the metal wiring 3 is placed on the wiring placement portion 9 of the ceramic substrate 2. Join. As a material of the metal wiring 3, it is desirable to use aluminum, an aluminum alloy, copper, or a copper alloy.

  As described above, the ceramic circuit board 1 is manufactured by executing the ceramic substrate injection molding process, the ceramic substrate degreasing process, the ceramic substrate firing process, and the circuit pattern forming process. The radiator-equipped ceramic circuit board 20 is manufactured by performing a metal base plate bonding process and a radiator mounting process on the ceramic circuit board 1. In the metal base plate bonding step, the metal base plate 5 is bonded to the back surface of the ceramic substrate 2 in the ceramic circuit substrate 1. The metal base plate 5 is formed of aluminum or an aluminum alloy. In order to bond the ceramic substrate 2 and the metal base plate 5, for example, in a state where an Al—Si brazing material (not shown) and the ceramic substrate 2 are stacked on the metal base plate 5, a vacuum furnace is used. It joins by heating at 630 degreeC.

  In the radiator mounting step, the metal base plate 5 and the heat sink 16 that is a radiator are joined by screws (not shown). The heat sink 16 is made of aluminum or an aluminum alloy, melts in a vacuum or an inert gas to obtain a melt, and then casts the melt into a mold having a predetermined shape in a vacuum or an inert gas to be cooled and solidified. Can be obtained. The heat sink 16 may be formed by sheet metal processing. Since a large current flows through the electronic components and circuits when the power module is in operation and heat is generated, the ceramic circuit board 1 can be cooled by circulating a refrigerant such as air or water around the heat sink 16.

  In addition, manufacture of the ceramic circuit board 20 with a radiator may perform a metal base board adhesion process after a ceramic substrate baking process, and may perform a circuit pattern formation process and a radiator attachment process after that.

  As described above, according to the ceramic circuit board 1 of the first embodiment, the ceramic circuit board 2 includes the ceramic board 2 and the plurality of metal wirings 3 (3a, 3b) arranged on the ceramic board 2 and connecting the electronic components. Since the substrate 2 includes the insulating portion 4 having a step between two adjacent metal wires 3a and 3b, the substrate 2 is an adjacent circuit wire without being enlarged by the insulating portion 4 of the ceramic substrate 2. The creepage distance between the metal wirings 3 can be increased, and the insulation reliability can be increased.

  According to the ceramic circuit board 20 with the radiator of the first embodiment, the ceramic circuit board 1 on which the electronic components are mounted and the back surface of the ceramic circuit board 1 that is opposite to the surface on which the electronic components are mounted are bonded. A metal base plate 5 and a heat sink 16 attached to the back surface of the metal base plate 5 opposite to the surface to which the ceramic circuit substrate 1 is bonded are provided. The ceramic circuit substrate 1 includes a ceramic substrate 2 and a ceramic substrate. 2 and a plurality of metal wirings 3 (3a, 3b) for connecting electronic components, and the ceramic substrate 2 includes an insulating portion 4 having a step between two adjacent metal wirings 3a, 3b. Because the insulation portion 4 of the ceramic substrate 2 is provided, the creeping distance between the metal wirings 3 which are adjacent circuit wirings is increased without increasing the whole size. Can, it is possible to improve the insulation reliability, the entire apparatus can be made compact.

  According to the method for manufacturing a ceramic circuit board of the first embodiment, a ceramic substrate injection molding process for forming a ceramic body having the shape of the ceramic circuit board 1 by injecting a ceramic material into a mold, and degreasing the ceramic body A ceramic substrate degreasing step, a ceramic substrate firing step for firing the ceramic body after the ceramic substrate degreasing step, and a circuit pattern for forming metal wiring on the ceramic body after the ceramic substrate firing step is performed The ceramic circuit board 1 includes a ceramic substrate 2 and a plurality of metal wirings 3 (3a, 3b) disposed on the ceramic substrate 2 and connecting electronic components. The ceramic substrate 2 includes: Since the insulating portion 4 having a step is provided between the two adjacent metal wirings 3a and 3b, the insulation of the ceramic substrate 2 is performed. By 4, without increasing the overall, it is possible to lengthen the creepage distance between the metal wires 3 is adjacent circuit wiring, it is possible to improve the insulation reliability.

Embodiment 2. FIG.
In the second embodiment, a ceramic substrate 2 formed by tape molding will be described. FIG. 4 is a schematic cross-sectional view of a ceramic circuit board according to Embodiment 2 of the present invention. The ceramic substrate 2 of Embodiment 2 is created using a plurality of green sheets. In FIG. 4, the ceramic substrate 2 produced using the two green sheets 17 and 18 is shown. From the green sheet 18, three insulating portions 4a, 4b, and 4c and upper portions of the outer peripheral portions 10a and 10b are formed. First, tape forming will be described.

  Tape forming is a method for producing a green sheet having a certain thickness from a mixture of ceramic raw material powder, a dispersion medium, a binder and the like. The green sheet is an unfired ceramic body formed into a thin plate shape. The green sheet is prepared by adjusting the slurry of the mixture, applying a doctor blade to the carrier sheet to a certain thickness, and drying. The green sheet has a thickness of several μm to several mm, and can be processed into a predetermined shape after being peeled off from the support (carrier sheet). In order to produce a molded body having the insulating portion 4, it can be efficiently produced by laminating and pressing two or more green sheets processed into a predetermined shape.

  Hereinafter, a method for manufacturing the ceramic substrate 2 by tape molding will be described. The ceramic substrate 2 by tape molding is executed in a ceramic substrate molding process. As the material of the green sheet, a ceramic material having high thermal conductivity, high strength, and extremely small thermal deformation is used. This material desirably contains at least one ceramic material of aluminum nitride, silicon nitride, aluminum oxide, zirconium oxide, silicon oxide, and silicon carbide. For aluminum nitride, it is desirable to use yttrium oxide as a sintering aid, and calcium oxide and magnesium oxide may be used.

  As the dispersion medium, a solvent composed of one or more selected from water, butanol, ethanol, propanol, methyl isobutyl ketone, toluene, and xylene is used according to the ceramic material to be used. As the binder, an organic binder composed of one or more selected from acrylic, cellulose, polyvinyl alcohol, polyvinyl acetal, polyvinyl butyral, urethane, and vinyl acetate is used. As the plasticizer, one or more organic compounds selected from phthalate esters, fatty acid esters, and glycol derivatives are used.

  The amount of the organic binder is suitably 8 to 14% based on the weight of the ceramic material. The tape molding is performed by a general method. The green sheets 17 and 18 are desirably formed to 0.5 to 1 mm. The green sheet 18 is punched into a predetermined shape by punching or machining center processing. The processed green sheet 17 and the flat green sheet 17 are laminated and bonded by pressing or hot pressing to form the ceramic substrate 2. The green sheet lamination method and the number of laminated sheets can be freely applied depending on the shape of processing. For example, the ceramic substrate 2 shown in FIG. 2 is a two-layered ceramic substrate, and is formed by a punch or machining center for forming an insulating portion from the flat green sheet 17 and the flat green sheet. The second green sheet 18 processed by the above is laminated.

  The ceramic substrate 2 formed by tape molding is degreased in a ceramic substrate degreasing step. Since many binders used for tape molding decompose at low temperatures, the furnace temperature is generally about 400 ° C. or lower. The firing of the ceramic substrate 2 in the ceramic substrate firing step is performed in a gas atmosphere such as air, nitrogen, argon or the like according to the ceramic material to be used, and the firing temperature is adjusted so that no continuous pores remain inside. If continuous pores remain in the interior, the thermal conductivity of the ceramic substrate deteriorates and a sufficient cooling effect cannot be obtained.

  Similarly to the first embodiment, the ceramic circuit board 1 using the ceramic substrate 2 according to the second embodiment is not adjacently enlarged by the insulating portion 4 of the ceramic substrate 2, and the metal wiring 3 that is an adjacent circuit wiring is used. The creepage distance between them can be increased, and the insulation reliability can be improved.

Embodiment 3 FIG.
Although the ceramic substrate 2 of Embodiment 1 and 2 demonstrated the example provided with the convex-shaped insulation part 4, the shape of the insulation part 4 is not limited to a convex shape. FIG. 5 is a schematic cross-sectional view of a first ceramic circuit board according to Embodiment 3 of the present invention, and FIG. 6 is a schematic cross-sectional view of a second ceramic circuit board according to Embodiment 3 of the present invention. FIG. 7 is a schematic cross-sectional view of a third ceramic circuit board according to Embodiment 3 of the present invention. FIG. 5 is an example of the ceramic substrate 2 provided with the insulating part 6 having a concave shape (a kind of hole shape), and FIG. 6 is an example of the ceramic substrate 2 provided with the insulating part 7 having one step. FIG. 7 is an example of the ceramic substrate 2 provided with the insulating portion 8 having a projection hole composite shape in which a convex shape and a concave shape are combined.

  The ceramic circuit board 1 shown in FIG. 5 includes three concave insulating portions 6a, 6b, and 6c on the ceramic board 2. The concave insulating portion 6a includes two side surfaces 11a and 11b and a bottom surface 12a. The concave insulating portion 6b includes two side surfaces 11c and 11d and a bottom surface 12b, and the concave insulating portion 6c includes two side surfaces 11e and 11f and a bottom surface 12c. The insulating part 4a is provided between the adjacent wiring arrangement part 9a and the wiring arrangement part 9b. The metal wiring 3a is joined to the wiring placement portion 9a, and the metal wiring 3b is joined to the wiring placement portion 9b. In FIG. 5, the concave insulating portion 6b is provided between the wiring arrangement portion 9a and the outer peripheral portion 10a, and the concave insulating portion 6c is provided between the wiring arrangement portion 9b and the outer peripheral portion 10b. Yes. The ceramic circuit board 1 shown in FIG. 5 is an example in which the height of the wiring arrangement portion 9 with respect to the back surface is higher than the height of the bottom surface 12 of the insulating portion 6. The ceramic circuit board 1 shown in FIG. 3 is an example in which the height of the wiring arrangement portion 9 with respect to the back surface is lower than the height of the upper surface 13 of the insulating portion 4. The symbol for the bottom surface is 12 as a whole, and 12a to 12c are used in the case of distinction. The reference sign of the concave insulating portion is 6 as a whole, and 6a to 6c are used in the case of distinction.

  The concave insulating portion 6a has a level difference corresponding to the height from the bottom surface 12a of the insulating portion 6a to the wiring placement portions 9a and 9b, that is, the height of the side surfaces 11a and 11b. The creeping distance between the adjacent metal wiring 3a and metal wiring 3b can be increased by the concave insulating portion 6a. The first ceramic circuit board 1 of the third embodiment has a long creepage distance between the metal wirings 3a and 3b which are adjacent circuit wirings without increasing the whole size by the concave insulating portion 6a of the ceramic substrate 2. Insulation reliability can be improved.

  The ceramic circuit board 1 shown in FIG. 6 includes insulating portions 7a and 7b having one step on the ceramic board 2. The insulating portion 7a includes a side surface 11a that forms a step. The insulating portion 7b includes a side surface 11b that forms a step. The insulating part 7a is provided between the adjacent wiring arrangement part 9a and the wiring arrangement part 9b. The insulating part 7b is provided between the adjacent wiring arrangement part 9b and the wiring arrangement part 9c. The metal wiring 3a is joined to the wiring placement portion 9a, the metal wiring 3b is joined to the wiring placement portion 9b, and the metal wiring 3c is joined to the wiring placement portion 9c. The ceramic circuit board 1 shown in FIG. 6 is also an example in which the height of the adjacent metal wiring 3 or the height of the adjacent wiring arrangement portion 9 is different. The reference numeral 7 for the insulating portion having one step is generally used, and 7a and 7b are used in the case of distinction.

  The insulating portion 7a has a step corresponding to the height from the wiring placement portion 9a to the wiring placement portion 9b, that is, the height of the side surface 11a. Similarly, the insulating portion 4b has a step corresponding to the height from the wiring placement portion 9c to the wiring placement portion 9b, that is, the height of the side surface 11b. The creeping distance between the adjacent metal wiring 3a and the metal wiring 3b can be increased by the insulating portion 7a having one step. Similarly, the creeping distance between the adjacent metal wiring 3c and the metal wiring 3b can be increased by the insulating portion 7b having one step. The second ceramic circuit board 1 of the third embodiment is formed between the metal wirings 3a and 3b, which are adjacent circuit wirings, without increasing the whole size by the insulating portions 7a and 7b having one step of the ceramic substrate 2. Further, the creeping distance between the metal wirings 3b and 3c can be increased, and the insulation reliability can be improved.

  The ceramic circuit board 1 shown in FIG. 7 includes three insulating portions 8a, 8b, and 8c having a composite shape of projection holes on the ceramic substrate 2. The projection hole composite-shaped insulating portion 8a includes four side surfaces 11a, 11b, 11c, and 11d, a bottom surface 12a, and two top surfaces 13a and 13b. The projection hole composite-shaped insulating portion 8b includes three side surfaces 11e, 11f, and 11g, a bottom surface 12b, and an upper surface 13c. The projection hole composite-shaped insulating portion 8c includes three side surfaces 11h, 11i, and 11j, a bottom surface 12c, and an upper surface 13d. The insulating part 8a is provided between the adjacent wiring arrangement part 9a and the wiring arrangement part 9b. The metal wiring 3a is joined to the wiring placement portion 9a, and the metal wiring 3b is joined to the wiring placement portion 9b. In FIG. 7, the projection hole composite shape insulating portion 8b is provided between the wiring arrangement portion 9a and the outer peripheral portion 10a, and the projection hole composite shape insulation portion 8c is provided between the wiring arrangement portion 9b and the outer peripheral portion 10b. Is provided. The ceramic circuit board 1 shown in FIG. 7 is an example in which the height of the wiring placement portion 9 with respect to the back surface is higher than the height of the bottom surface 12 of the insulating portion 8 and lower than the height of the upper surface 13. The reference numeral of the insulating portion of the projection hole composite shape is generally 8 and 8a to 8c are used in the case of distinguishing the description.

  The insulating portion 8a having the projection hole composite shape has a height from the bottom surface 12a to the upper surfaces 13a and 13b of the insulating portion 8a, that is, a step corresponding to the height of the side surfaces 11b and 11c, and a height from the upper surface 13a to the wiring placement portion 9a. That is, there is a step corresponding to the height of the side surface 11a and a height from the upper surface 13b to the wiring placement portion 9b, that is, a step corresponding to the height of the side surface 11d. The creeping distance between the adjacent metal wiring 3a and the metal wiring 3b can be increased by the insulating portion 8a having the projection hole composite shape. The third ceramic circuit board 1 according to the third embodiment has a creeping distance between adjacent metal wirings 3a and 3b without increasing the size of the whole by the insulating portion 8a having the projection hole composite shape of the ceramic board 2. The insulation reliability can be improved.

  As described in the first embodiment, the height of the surface of the wiring placement portion 9 on which the metal wiring 3 is placed with respect to the back surface of the ceramic substrate 2 is the height of the insulating portion 4 positioned around the wiring placement portion 9. In the structure lower than the height, when the metal wiring 3 is bonded by brazing, the side surface 11 of the insulating portion 4 formed on the ceramic substrate 2 serves as a wall to prevent leakage of the brazing material (not shown). Can do. The same applies to the insulating portion 8 shown in FIG. Further, in the case of the insulating portion 7 shown in FIG. 6, that is, when the height between the adjacent wiring arrangement portions 9 is different, the side surface 11 of the insulating portion 7 serves as a wall when the metal wiring 3 is bonded by brazing. And leakage of brazing material (not shown) can be prevented.

  When changing the shape of the insulating parts 4, 6, 7, 8 and the like, for example, in the injection molding method, the nesting of the injection mold is replaced and re-applied according to the shape of the insulating parts 4, 6, 7, and 8. Since it only needs to be arranged, it can be easily changed. Even with the tape forming method, when the green sheet is processed, it is only necessary to change the machining center program, so that the shapes of the insulating portions 4, 6, 7, and 8 can be easily changed.

Embodiment 4 FIG.
In the first to third embodiments, the metal circuit pattern is bonded and formed by brazing the metal wiring 3 to the ceramic substrate 2. However, the metal wiring 3 can be melt bonded to the ceramic substrate 2.

  FIG. 8 is a diagram showing a manufacturing process of the ceramic circuit board according to the fourth embodiment of the present invention, and FIG. 9 is a diagram showing a main part of the ceramic circuit board according to the fourth embodiment of the present invention. As shown in FIG. 8, aluminum or aluminum alloy, which is a foil-like metal wiring member 15, is disposed on the insulating portions 4 a and 4 b formed by injection molding or tape molding. Thereafter, by heating to 700 ° C. or higher in a vacuum or an inert gas, the metal wiring member 15 is melted and solidified by cooling, whereby the metal wiring 3 is joined to the ceramic substrate 2 as shown in FIG.

  As shown in FIGS. 3, 6, 7, and 8, the height of the surface of the wiring placement portion 9 on which the metal wiring 3 is placed with respect to the back surface of the ceramic substrate 2 is positioned around the wiring placement portion 9. If the structure is lower than the height of the insulating portion (insulating portion 4 in FIGS. 3 and 8, insulating portion 7 in FIG. 6, insulating portion 8 in FIG. 7) or the outer peripheral portion 10, leakage of the molten metal wiring member 15 is prevented. be able to. Further, the volume of the space formed by the wiring arrangement portion 9 and the side surfaces 11a and 11b as shown in FIG. 8 and the volume of the space formed by the side surface of the outer peripheral portion 10, the side surface 11 of the insulating portion 4 and the wiring arrangement portion 9 are as follows. Even if the metal wiring member 15 becomes excessive, the excess metal wiring member 15 can be deleted by grinding the excess by machining.

  Further, even when aluminum powder or an aluminum-containing paste is used for the metal wiring member 15, the metal wiring 3 can be similarly bonded to the ceramic substrate 2. When aluminum powder is used, finer metal wiring 3 can be formed, and a finer circuit pattern can be formed. A predetermined amount of aluminum powder is applied to the wiring placement portion 9 surrounded by the side surface 11 of the insulating portion 4 formed by injection molding or tape molding, or to the wiring placement portion 9 surrounded by the side surface 11 of the insulating portion 4 and the outer peripheral portion 10. Fill. The insulating portion 4 formed at this time is surrounded by the side surface 11 of the insulating portion 4 and the side surface of the outer peripheral portion 10 so that the wiring placement portion 9 where the metal wiring 3 is formed becomes a concave bottom. It is necessary to form so that it may be. The aluminum powder is melted by heating to 700 ° C. or higher in a vacuum or an inert gas, and bonded to the ceramic substrate 2 by cooling and solidifying.

  Similarly to the first embodiment, the ceramic circuit board 1 according to the fourth embodiment is creeping between the metal wirings 3 that are adjacent circuit wirings without increasing the whole size by the convex insulating portion 4 of the ceramic substrate 2. The distance can be increased and the insulation reliability can be increased.

  In the ceramic circuit board 1 according to the fourth embodiment, the brazing material layer between the metal wiring 3 and the ceramic substrate 2 can be eliminated by directly joining the metal wiring 3 and the ceramic substrate 2 constituting the circuit pattern. Since the ceramic circuit board 1 of the fourth embodiment can eliminate the brazing material layer between the metal wiring 3 and the ceramic substrate 2, the thermal conductivity between the ceramic board 2 and the metal wiring 3 is increased, and the heat dissipation is improved. . Moreover, the ceramic circuit board 1 of Embodiment 4 can eliminate a brazing process (soldering process), and can reduce a man-hour and cost.

  Although the above-described fusion bonding method has been described in the example of applying to the ceramic substrate 2 provided with the convex insulating portion 4, the ceramic substrate 2 provided with the insulating portion 8 having the projection hole composite shape shown in FIG. 6 can also be applied to the metal wiring 3 of the wiring arrangement portions 9a and 9c in the ceramic substrate 2 provided with the insulating portion 7 having one step.

  The ceramic circuit board 1 of the present invention is suitable for mounting a semiconductor element in which a large current flows and generates a large amount of heat. The semiconductor element may be a general element based on a silicon wafer, but in the present invention, the band gap is wider than silicon such as silicon carbide (SiC), gallium nitride (GaN) -based material, or diamond. Wide band gap semiconductor material can be applied. The device type of the semiconductor element is not particularly limited, but a switching element such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field-Effect-Transistor) or a rectifying element such as a diode is mounted. can do. For example, when silicon carbide (SiC), gallium nitride (GaN) -based material, or diamond is used for a semiconductor element functioning as a switching element or a rectifying element, the conventional element made of silicon (Si) is used. However, since the power loss is low, it is possible to increase the efficiency of the semiconductor device on which the semiconductor element is mounted. In addition, since the withstand voltage is high and the allowable current density is high, the ceramic circuit board 1 on which the semiconductor element (wide band gap semiconductor element) to which the wide band gap semiconductor material is applied can be miniaturized. Furthermore, since the wide band gap semiconductor element has high heat resistance, it can operate at a high temperature, and the heat sink 16 can be downsized and the water cooling part can be air cooled. The substrate 20 can be further downsized.

  Moreover, although the convex shape has been described as an example of the protrusion shape, a shape without the upper surface 13 or a shape with the side surface 11 not flat may be used. Although the concave shape has been described as an example of the hole shape, a shape having no bottom surface 12 or a shape in which the side surface 11 is not flat may be used. Within the scope of the present invention, the present invention can be combined with each other, or can be appropriately modified or omitted.

  DESCRIPTION OF SYMBOLS 1 ... Ceramic circuit board, 2 ... Ceramic board | substrate, 3, 3a, 3b, 3c, 3d ... Metal wiring 4, 4a, 4b, 4c ... Insulation part, 5 ... Metal base board, 6, 6a, 6b, 6c ... Insulation , 7, 7a, 7b ... insulating part, 8, 8a, 8b, 8c ... insulating part, 9, 9a, 9b, 9c, 9d ... wiring placement part, 11, 11a, 11b, 11c, 11d, 11e, 11f, 11g, 11h, 11i, 11j ... side face, 15 ... metal wiring member, 16 ... heat sink, 17 ... green sheet, 18 ... green sheet, 20 ... ceramic circuit board with radiator.

Claims (8)

A ceramic circuit board on which electronic components are mounted,
A ceramic substrate having a plurality of wiring arrangement portions, and a plurality of metal wirings arranged on the ceramic substrate and connecting the electronic components,
The ceramic substrate includes an insulating portion having a step between two adjacent metal wirings,
The insulating portion is located on a bottom surface, a first upper surface located on one metal wiring side of the two adjacent metal wirings, and on the other metal wiring side of the two adjacent metal wirings. Positioned between a second upper surface, a first side surface located between the wiring placement portion provided with the one metal wiring and the first upper surface, and between the first upper surface and the bottom surface A second side surface, a third side surface located between the bottom surface and the second top surface, and the wiring placement portion provided with the other metal wiring and the second top surface. Having a fourth side located,
The height of each of the wiring placement portions where the two adjacent metal wirings are placed is higher than the height of the bottom surface and lower than the heights of the first top surface and the second top surface,
The distance from the one metal wiring to the first side surface, the width of the first top surface, the bottom surface, and the front second top surface, and the first side surface, the second side surface, and the third surface And the sum of the distance from the other metal wiring to the fourth side is required for insulation between the two adjacent metal wirings. A ceramic circuit board characterized by having a creepage distance greater than that.   The ceramic circuit board according to claim 1, wherein the metal wiring is aluminum or an aluminum alloy.   The ceramic circuit board according to claim 1, wherein the ceramic board contains at least one of aluminum nitride, aluminum oxide, zirconium oxide, and silicon nitride. A ceramic circuit board on which electronic components are mounted;
A metal base plate bonded to the back surface of the ceramic circuit board on the side opposite to the surface on which the electronic component is mounted;
A heat sink attached to the back surface located on the opposite side of the surface to which the ceramic circuit board is bonded in the metal base plate;
The ceramic circuit board according to claim 1, wherein the ceramic circuit board is a ceramic circuit board according to claim 1. A method for manufacturing a ceramic circuit board for manufacturing the ceramic circuit board according to any one of claims 1 to 3,
A ceramic substrate injection molding step of injecting a ceramic material into a mold to form a ceramic body having the shape of the ceramic circuit board;
A ceramic substrate degreasing step for degreasing the ceramic body;
A ceramic substrate firing step of firing the ceramic body after the ceramic substrate degreasing step is performed;
A circuit pattern forming step for forming the metal wiring on the ceramic body after the ceramic substrate firing step is performed. A method for manufacturing a ceramic circuit board for manufacturing the ceramic circuit board according to any one of claims 1 to 3,
A green sheet of flat ceramic material and a green sheet of ceramic material processed according to the shape of the wiring arrangement part for arranging the insulating part and the metal wiring are laminated to have the shape of the ceramic circuit board. A ceramic substrate forming process for forming a ceramic body;
A ceramic substrate degreasing step for degreasing the ceramic body;
A ceramic substrate firing step of firing the ceramic body after the ceramic substrate degreasing step is performed;
A circuit pattern forming step for forming the metal wiring on the ceramic body after the ceramic substrate firing step is performed. A method for manufacturing a ceramic circuit board for manufacturing the ceramic circuit board according to any one of claims 1 to 3,
A ceramic substrate injection molding step of injecting a ceramic material into a mold to form a ceramic body having the shape of the ceramic circuit board;
A ceramic substrate degreasing step for degreasing the ceramic body;
A ceramic substrate firing step of firing the ceramic body after the ceramic substrate degreasing step is performed;
A circuit pattern forming step for forming the metal wiring in the ceramic body after the ceramic substrate firing step is performed,
The circuit pattern formation step includes forming a metal wiring by melting a metal wiring member configured in any of a metal foil shape, a metal powder shape, and a metal-containing paste shape, thereby manufacturing the ceramic circuit board Method. A method for manufacturing a ceramic circuit board for manufacturing the ceramic circuit board according to any one of claims 1 to 3,
A green sheet of flat ceramic material and a green sheet of ceramic material processed according to the shape of the wiring arrangement part for arranging the insulating part and the metal wiring are laminated to have the shape of the ceramic circuit board. A ceramic substrate forming process for forming a ceramic body;
A ceramic substrate degreasing step for degreasing the ceramic body;
A ceramic substrate firing step of firing the ceramic body after the ceramic substrate degreasing step is performed;
A circuit pattern forming step for forming the metal wiring in the ceramic body after the ceramic substrate firing step is performed,
The circuit pattern formation step includes forming a metal wiring by melting a metal wiring member configured in any of a metal foil shape, a metal powder shape, and a metal-containing paste shape, thereby manufacturing the ceramic circuit board Method.

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