JP2002246710A - Ceramic circuit board integrated base board and its producing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component mounting board, having low thermal resistance and exhibiting superior thermal cycle resistance in which a base board and a ceramic circuit board are integrated. SOLUTION: The electronic component mounting board comprises a base board, a ceramic substrate 5 smaller than the base board placed on the principal plane of the base board, and a metal layer 4 provided to cover both the base board and the ceramic substrate, at least partially where the metal layer has a planar surface which does not touch the base board and the ceramic substrate. The base board is a compound material of 6 of metal-metal, metal-carbon or metal-ceramic, wherein the metal in the compound material and the metal layer mainly comprise copper and the purity of metal in the metal layer is higher than that of the compound material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base material made of a metal-metal, metal-carbon, or metal-ceramic composite containing a metal containing copper as a main component and a high thermal conductive ceramic substrate formed integrally. The present invention relates to an electronic device mounting substrate or a base plate-integrated ceramic circuit substrate and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, in the field of industrial equipment, the development of power modules used in inverters for electric motors and the like has been advanced. One having a structure soldered to a base has been used. However, cracks are formed in the ceramic substrate and the solder layer depending on the use conditions, and various improvements have been made to improve reliability by preventing such cracks.

For example, Al (aluminum) -SiC
(SiC) Composite with base material, Al with Al circuit
N (aluminum nitride) substrate (hereinafter referred to as Al-SiC composite / aluminum nitride substrate with Al circuit)
The structure where is soldered retains practical characteristics even after 3000 times of thermal cycling.
Although it has much higher reliability than the aluminum nitride substrate with the base / copper circuit, it has a larger thermal resistance than the conventional structure, so that it is necessary to increase the chip size, and the Al-SiC composite is expensive. For this reason, there is a problem such as an increase in module cost, and it has not yet been widely used.

It has also been proposed to integrate the Al-SiC composite with a ceramic substrate or a ceramic circuit substrate when manufacturing the Al-SiC composite. In this case, since there is no solder layer between the composite / substrate, there is no risk of cracking in the solder at that portion, and the reliability is improved, and there are advantages such as a decrease in thermal resistance.
The thermal conductivity of the Al-SiC composite is only 200 W / mK at most, and further reduction in thermal resistance is required for increasing the capacity and miniaturization of the power module.

[0005]

SUMMARY OF THE INVENTION The present inventor has made various studies in view of the above-mentioned circumstances, and has merely performed a process of manufacturing a metal-metal, metal-carbon, or metal-ceramic composite, and has been able to form a base plate with a base plate. The present inventors have found that a ceramic circuit board can be integrated, a thermal cycle resistance can be obtained, and a substrate for mounting an electronic component having a low thermal resistance can be provided, and the present invention has been accomplished. That is, an object of the present invention is to provide an electronic mounting substrate and a base plate-integrated ceramic circuit substrate capable of supplying a power module having low thermal resistance, excellent thermal cycle resistance, and therefore excellent long-term reliability with high reproducibility. It is in.

[0006]

According to the present invention, there is provided a base plate having or not having a concave portion on one main surface, and a ceramic substrate disposed on the main surface of the base plate and smaller than the base plate. A metal layer provided so as to cover at least a part of the base plate and the ceramic substrate together, a surface of the metal layer not in contact with the base plate and the ceramic substrate is planar, and The base plate is a metal-metal, metal-carbon, or metal-ceramic composite, the metal in the composite and the metal layer are mainly composed of copper, and the purity of the metal layer in the composite is An electronic device mounting substrate characterized by being higher in purity than metal.

The present invention also provides the electronic device mounting substrate described above, wherein the substrate has a plurality of ceramic substrates. Further, the present invention is a ceramic circuit board integrated with a base plate, wherein a circuit is formed from a metal layer of a substrate for mounting an electronic device.

Further, the present invention provides a base plate integrated type comprising a ceramic circuit board having a circuit on one main surface and a base plate provided in contact with a main surface of the ceramic circuit board on which no circuit is provided. A ceramic circuit board, wherein the base plate is made of a metal-metal composite, a metal-carbon composite, or a metal-ceramic composite, and the ceramic substrate of the circuit surface and the base plate is mounted and no ceramic substrate is provided. A base having the same surface height, wherein the metal contained in the circuit and the base plate is mainly composed of copper, and the purity of the metal layer is higher than the purity of the metal in the composite. This is a board-integrated ceramic circuit board.

Further, according to the present invention, the base plate is made of carbon,
A composite formed by impregnating a porous compact mainly containing at least one selected from silicon carbide, copper oxide, alumina, aluminum nitride, silicon nitride, tungsten and molybdenum with a metal mainly containing copper This is a base plate-integrated ceramic circuit board.

Further, the present invention comprises at least one selected from the group consisting of carbon, silicon carbide, copper oxide, alumina, aluminum nitride, silicon nitride, tungsten and molybdenum, and has or has a recess on one main surface. A ceramic substrate is disposed on the main surface of the porous molded body, and a metal plate mainly composed of copper is disposed so as to cover at least a part of the porous molded body and the ceramic substrate together. And disposing the laminate in a container, casting a metal containing copper as a main component, impregnating the voids of the porous molded product with the metal containing copper as a main component, And a metal plate and a ceramics substrate are integrated with each other.

Further, the present invention comprises at least one selected from the group consisting of carbon, silicon carbide, copper oxide, alumina, aluminum nitride, silicon nitride, tungsten and molybdenum, and has or has a recess on one main surface. A ceramic substrate is arranged on the main surface of the porous molded body, and a metal plate is further arranged to cover at least a part of the porous molded body and the ceramic substrate together to form a laminate; Is placed in a container, a metal containing copper as a main component is cast, and the voids of the porous product are impregnated with the metal containing copper as a main component. And then forming a circuit from the metal layer formed on the surface of the ceramic substrate opposite to the base plate or from the metal plate. Scan circuit is a manufacturing method of the substrate.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The substrate for mounting electronic equipment according to the present invention comprises:
According to the method of manufacturing a metal-metal, metal-carbon, or metal-ceramic composite serving as a base plate, there is a feature that the base plate and the ceramic substrate can be integrated to produce the base plate.

The methods for producing a metal-metal, metal-carbon, or metal-ceramic composite are roughly classified into two types: an impregnation method and a powder metallurgy method. Among them, the powder metallurgy method has a low production cost but is not sufficient in terms of the characteristics of the obtained composite, and the impregnation method has a high production cost but is superior in the characteristics of the obtained composite. There are various impregnation methods, and there are a method performed at normal pressure and a method performed under high pressure (high-pressure casting method). What is performed under high pressure includes a molten metal forging method and a die casting method. Both the melt forging method and the die casting method have a porous material having a certain degree of strength in a mold having a final shape or a shape close to the final shape, or a mold (or room) composed of a frame and a plate. A body (preform) is loaded and copper (C)
u) Alternatively, this is a method of impregnating a molten Cu alloy at a high pressure to obtain a composite.

In the present invention, any method may be used.
The type which is performed under high pressure is preferable from the viewpoint of characteristics (both high thermal conductivity and low thermal expansion coefficient and thermal cycle resistance). When performing the impregnation operation, joining the ceramic board and the circuit board, or
If the metal layer for the circuit is formed, it is possible to obtain the precursor of the circuit board in which the ceramic substrate is bonded at a lower cost.

In the case where the preform is impregnated with the molten Cu and integrated with the substrate at the same time, (1) a ceramic circuit board is placed in contact with the preform, and the ceramic is mixed with the ceramic while impregnating the preform with the molten Cu. (2) Place the ceramic substrate in contact with the preform, and impregnate the preform with the molten Cu,
There has been known a method of simultaneously performing bonding with a ceramic substrate and forming a circuit metal layer.

The method (1) requires a step of bonding a circuit metal to a ceramic substrate in advance or forming a circuit after providing a metal layer on the ceramic substrate, which is disadvantageous in cost. In the method (2), since a copper alloy having a low melting point is often used as the impregnated metal, the thermal conductivity and the electric conductivity of the impregnated metal layer used in the circuit are reduced, which is disadvantageous in characteristics. Further, since the alloy is harder than pure copper, the stress generated in the joined ceramic substrate such as AlN increases the stress, which may cause a problem such as substrate cracking. When pure copper is used as the impregnated metal, adhesion to ceramics is poor, and the heat cycle resistance may be reduced.

As a result of intensive studies, the present inventors have made it possible to manufacture a metal-metal or metal-ceramic by relatively easily manufacturable, accurate, and inexpensively by adopting the following structure. It has been found that an integrated ceramic circuit board with a base plate made of a composite can be obtained.

That is, a ceramic substrate is placed in contact with the preform, and a Cu plate is placed in contact with the ceramic substrate, preheated, and impregnated with molten Cu at high pressure to obtain a substrate for mounting electronic components. By forming a circuit from the Cu plate by a conventionally known method such as etching, it is possible to obtain a base plate-integrated ceramic circuit board to which a circuit made of a Cu plate having a constant thickness is joined.

When the preform is impregnated with Cu, Cu
In general, preheating is performed so that the molten metal is easily impregnated into the preform. However, in the present invention, during the preheating, the Cu plate does not melt even if a Cu plate is present. Further, even if a Cu alloy comes into contact with a Cu plate,
It is based on the discovery that the u-plate maintains its input configuration.

Surprisingly, it has been found that the ceramic circuit board integrated with the base plate thus obtained has extremely useful characteristics in practical use. For example, Cu-Si
The coefficient of thermal expansion of the C composite plate is determined by the volume percentage of SiC in the composite, and is generally about 6 to 9 ppm / K. Therefore, AlN (aluminum nitride) or S
When a ceramic substrate having a low coefficient of thermal expansion such as i ₃ N ₄ (silicon nitride) is soldered or brazed, a large warpage having a convex ceramic side is generated. This warp creates a gap between the base plate and the radiating fins when fixing the warping to the radiating fins or the like with screws, which hinders heat transfer. For this reason, it has been necessary to provide the base plate with a warp in which the joint surface with the radiation fin or the like is concave by some method in advance. However, in the ceramic circuit board integrated with a base plate of the present invention, since the coefficient of thermal expansion of Cu constituting the surface circuit is large, AlN is substantially flat, and Si ₃ N ₄ having a smaller coefficient of thermal expansion than AlN is used. In this case, the circuit slightly warps to make the circuit convex, but the degree of the warp is such a degree that the circuit side can be changed to warp to make the circuit side concave in the module assembling process, which is extremely preferable in practical use. Express characteristics.

Hereinafter, the present invention will be described in detail with reference to an example in which a Cu—SiC composite is produced by an impregnation method under a high pressure.
First, a method for producing a Cu—SiC composite will be described. Si
C powder is molded and calcined to obtain a preform, placed on a partition plate whose surface has been subjected to a release treatment, and then set in a frame-shaped mold that has been hollowed out so that its inner dimensions are in the final shape. . After pre-heating the block in which the blocks are stacked and fixed, they are placed in a pressure-resistant container, and the molten copper is poured into the container as quickly as possible to prevent the temperature of the block from lowering, and the molten copper is pressurized. , Cu is impregnated into a preform placed in a frame-shaped mold.

In the present invention, when the preform is set in a frame-shaped mold in the above process, the Al-SiC
By the same operation as that for obtaining the composite, an electronic component mounting substrate in which the base plate and the ceramic circuit substrate are integrally joined, or a base-integrated ceramic is obtained.

In the above operation, it is convenient to provide a recess having the same area as that of the ceramic substrate on one principal surface of the preform and to dispose the ceramic substrate therein, thereby achieving accurate positioning. Furthermore, it is preferable that the outer dimensions of the metal plate for the circuit be the same as the inner dimensions of the frame, because no misalignment will occur in later handling, and no positioning or the like will be required in subsequent steps.

As is clear from the above description, the porous silicon carbide preform to be used does not need to be specially limited, and any type can be used. It is preferable to select one having the following characteristics. That is, particularly important characteristics among the characteristics of the Cu—SiC composite are the thermal conductivity and the coefficient of thermal expansion. The higher the content of silicon carbide (SiC) in the composite, the lower the coefficient of thermal expansion, but the lower the thermal conductivity. Therefore, the relative density of the porous silicon carbide is practically 30 to 70% by volume.
Is preferably within the range. In addition, the strength of the preform is preferably 3 MPa or more in bending strength, since there is no fear of cracking during handling or impregnation.

It is preferable that silicon carbide (SiC) powder, which is a raw material of the porous silicon carbide, be blended with a particle size. This is because the coarse powder alone has poor strength development, and the fine powder alone lowers the thermal conductivity. According to the study of the present inventors, for example, silicon carbide coarse powder 4 having a particle size of # 350 or more
It is preferable to use a mixture of 0 to 80% by mass and 60 to 20% by mass of silicon carbide fine powder having a particle size of # 1000 or less.

The carbon, ceramics or metal powder or fiber is formed into a preform through the steps of degreasing and firing, and is subjected to the impregnation operation. As described above, since it is more advantageous for the preform to have the recess for positioning the ceramic substrate in the process, the molding method is preferably injection molding, dry molding, molding using a mold such as wet molding. . In the case of extrusion molding, it is not easy to provide a dent on the main surface. However, since the problem of positioning can be reduced by devising the stuffing of the frame, for example, by making the dent a groove, the same method is used. It is possible.

In order to make the strength of the preform 3 MPa or more, it is preferable that the preform is fired in a non-oxidizing atmosphere or an oxidizing atmosphere, and the firing temperature is 850 ° C. or more. SiC for silicon carbide (SiC) preform
When calcination is performed in air, it is preferable that the calcination be performed at a temperature not exceeding 1100 ° C. so that the thermal conductivity does not decrease due to oxidation.

The frame material for accommodating the preform has a gate for introducing the molten Cu into the mold (in the room), and iron is effective. Obtained by laser processing or punching press, and provided after release treatment. For the release treatment, fine graphite powder is effective. Further, the partition plate is preferably an iron or stainless plate. It is extremely effective for mold release to apply fine graphite and / or BN (boron nitride) after performing treatments such as oxidation prevention. The thickness of the partition plate is selected according to the thickness and accuracy of the target product. If the thickness variation of the product is to be suppressed to 20 μm or less, a plate of 3 mm or more may be used, and if about 50 μm is allowed, the thickness may be reduced to about 0.3 mm.

As the ceramic substrate used in the present invention, general-purpose ceramics such as AlN, Si ₃ N ₄ and Al ₂ O ₃ (alumina) are used. For the purpose of the present invention, ceramics having high thermal conductivity are used. Preferably
Preference is given to nitride ceramics such as AlN and Si ₃ N ₄ .

The circuit metal plate in the present invention may be of any type as long as it has a higher melting point than the impregnated metal constituting the base plate. Further, those having high thermal conductivity and high electrical conductivity are preferable, and any Cu plate having a purity of 98.5% by mass or more can be used. However, in order to achieve both higher reliability and excellent physical properties, the purity of the Cu plate is at least 99.5%, more preferably at least 99.9%.
In particular, an oxygen-free copper plate is preferably used. The thickness of the circuit material is generally about 0.2 to 0.5 mm, but when the ceramic substrate is AlN, the thickness is 0.2 to 0.4 mm.
preferably 0.3~0.5mm For i ₃ N _4.

The metal plate for a circuit can be used not only as a circuit material but also as a positioning material. For example, when a preform is formed by extrusion molding or the like, it is difficult to process a cavity for placing a ceramic substrate, so a metal plate for a circuit having a hollow hole for accommodating a ceramic substrate is placed in contact with the preform and positioned. In this method, a ceramic substrate is arranged as a jig, and a metal plate for a circuit is arranged thereon. In this case, in order to facilitate the intrusion of the molten Cu, it is preferable to provide a through hole in the metal plate for positioning in addition to the substrate position. Further, the circuit metal plate may be used by cutting out unnecessary portions.

A preform, a ceramic substrate, and a metal plate for a circuit, which are housed in a room separated by a frame and a partition plate, are laminated and fixed to form a block for impregnation, and the block is placed in a preheating furnace and preheated. I do. The preheating temperature needs to be an appropriate temperature depending on the metal to be impregnated, and the upper limit temperature must be lower than the melting point of the circuit metal plate. According to an experimental study by the present inventors, the preform is a porous silicon carbide sintered body, the impregnated metal is a Cu alloy containing 3% by mass of Si and 0.7% by mass of Mg, When oxygen-free copper is used as the metal plate for
70 ° C. is a preferred range. If the temperature is lower than 1000 ° C., impregnation may be defective. If the temperature is higher than 1070 ° C., the oxygen-free copper plate may be melted. Further, in order to prevent the copper plate from being oxidized during the preheating, it is necessary to heat in an inert atmosphere or a reducing atmosphere as necessary.

The preheated impregnating block is placed in a pressure-resistant container, and the molten Cu alloy is pushed into the pressure-resistant container and pressurized to impregnate the preform with the molten alloy and simultaneously with the ceramic substrate. Complete bonding with the circuit metal plate. When a high-purity Cu plate having a purity of 99.5% or more is used as the circuit metal plate, and the Cu alloy to be impregnated is a combination of the above compositions, the temperature of the supplied Cu alloy is 110
If it is 0 to 1200 ° C, there is no problem. If the temperature is lower than the above range, impregnation failure may occur, and if the temperature is higher, melting of the high-purity Cu plate may occur. Also, C
In order to prevent oxidation of the u alloy melt, the melt is preferably maintained in an inert atmosphere or a reducing atmosphere.

The metal to be impregnated only needs to have a lower melting point than the metal plate for a circuit. When the metal plate for a circuit is an oxygen-free copper plate, a Cu alloy is selected. The reason why the Cu alloy is preferably selected is that it melts below the melting point of the oxygen-free copper plate, shows a strong bond with the preform or the ceramic substrate, and does not fuse with the oxygen-free copper plate on the surface to form a brittle alloy. This is because the object of the present invention can be sufficiently achieved.

The Cu alloy is preferably a Cu alloy containing a component whose melting point is lowered by adding a small amount. However, a small amount of P (phosphorus) lowers the melting point, but undesirably lowers the thermal conductivity. Among various Cu alloys, Cu-S
i-based alloys are preferred. This is because Si lowers the melting point by a smaller amount than the other additive elements, and the decrease in thermal conductivity is small. The amount is 0.5 to 10% by mass, preferably 1.
0-5.0 mass% is preferable. Further, the Cu-Si alloy obtained by adding a small amount of a Group 2a element such as Mg and Ca, a Group 3a element such as Y, or a Group 4a element such as Ti or Zr can provide a stronger bond with ceramics. Is more preferable. A sufficient effect can be obtained when the amount of the above-mentioned additional element is 1% by mass or less.

After completion of the impregnation operation, after cooling and solidification, C
The u alloy is cut off, the contents are decomposed, and the release material on the surface is removed by buffing, sandblasting, etc.
-A substrate is obtained in which a ceramic substrate is mounted on one main surface of the SiC composite, and a circuit metal plate is bonded to at least a part of the surfaces of both. The substrate is
A base plate-integrated ceramic circuit capable of mounting various electronic devices such as semiconductor elements by simply forming a circuit from the circuit metal plate by etching or the like, and by performing processing and plating as needed. A substrate can be easily provided.

In the operation of obtaining the substrate, a substrate having a plurality of ceramic circuit boards mounted on one base plate is obtained only by previously disposing a plurality of ceramic substrates on one main surface of the preform. This substrate has an advantage that it can easily provide a module having a structure in which a plurality of ceramic circuit boards are mounted on one base plate, and contributes to a higher density of electronic components.
In any of the above cases, the surface of the base plate-integrated ceramic circuit board of the present invention is formed on the same plane as the surface of the circuit and the surface of the metal layer on the surface of the base plate.

The metal layer on the surface of the base plate can be partially or entirely removed in the course of etching or the like. However, according to the study of the present inventors, in a normal case, it is more than 3 mm from the end of the circuit. In the case of low voltage application, it is sufficient to etch a region of 1 mm or more, and the removal of a region more than 1 mm only increases the etching amount and does not contribute to improvement of circuit characteristics.

The case where the Cu—SiC composite material is used for the base plate has been described in detail above. Instead of silicon carbide powder, powders of carbon, alumina, aluminum nitride, silicon nitride, tungsten, molybdenum, copper oxide and the like are used. Alternatively, even when fibers are used, the substrate of the present invention can be obtained in substantially the same manner as when the SiC powder is used. When metal powder is used, a cold isostatic press (CI
P) A preform can be obtained by molding, and
In the impregnation step, it is important to keep the atmosphere in a non-oxidizing atmosphere or a reducing atmosphere, and the impregnated metal is preferably one to which a trace amount of a 4a group element is added. When fibers are used, preforms can be made by casting or the like for short fibers, and preforms can be made by weaving them into cloth for long fibers.

In addition to the method of impregnating under high pressure using a preform described in detail, a metal powder and a metal powder, a metal powder and a carbon powder, or a metal powder and a ceramic powder constituting a composite as a base plate are mixed. Mix and heat it above the melting point of the matrix metal and inject it into the forming mold with the circuit metal plate and ceramic plate arranged inside to produce a substrate with integrated substrate and base plate You can also. For portions other than the matrix metal, a fibrous substance can be used other than the powder.

[0041]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 Silicon Carbide Powder A (NG-220, manufactured by Taiyo Random Co., Ltd., average particle size: 60 μm) 70
g, silicon carbide powder B (GC-1000 manufactured by Yakushima Electric Works Co., Ltd.)
F, 30 g of an average particle diameter: 10 μm) and 10 g of silica sol (Snowtex, manufactured by Nissan Chemical Industries, Ltd.) were weighed and mixed for 30 minutes with a stirring mixer.
110mm with 50mm x 0.6mm cavity
It was formed into a flat plate having dimensions of × 90 mm × 4.6 mm. At this time, the pressure during molding was 10 MPa.

The obtained molded body was heated in the air at a temperature of 950 ° C.
For 2 hours to obtain a porous silicon carbide sintered body having a relative density of 65% by volume.

Next, the obtained porous silicon carbide sintered body was
Placed on a 0.7 mm thick partition plate coated with a release agent,
This was also placed in the mold (material: carbon steel) of FIG. 1 coated with a release agent, and 5 μm was placed in the cavity of the porous silicon carbide sintered body.
After inserting an aluminum nitride substrate having a characteristic of 170 W / mK of 0 × 50 × 0.6 mm, an oxygen-free copper plate having a thickness of 0.3 mm equal to the outer dimension of the porous silicon carbide sintered body was placed thereon. . In this state, the height of the contents and the frame height become substantially equal. A partition plate coated with a release agent (similar to the above-described partition plate and having the same size as the outer shape of the mold) was overlaid thereon, and a 6 mm-thick iron plate was arranged on both ends to form one block.

Next, the block was heated in an electric furnace at a temperature of 105 ° C.
After preheating to 0 ° C and placing in a preheated mold, 2% by mass of Si heated to a temperature of 1100 ° C,
Pour molten metal of Cu alloy containing 0.5% by mass of Ti
The porous silicon carbide sintered body was impregnated with a Cu alloy by applying a pressure of 00 MPa for 10 minutes. After cooling to room temperature, the obtained metal lump including the composite was cut with a band saw, and the base plate-integrated ceramic substrate was released from the mold. FIG. 2 shows a sectional view of this state.

In order to remove the release agent from the surface of the base plate-integrated ceramic substrate, the ceramic substrate was passed through a buffing machine equipped with a # 220 baffle. After removing the release agent, an etching resist having a desired pattern was printed on the surface of the copper plate, the back surface and the side surfaces were solid-coated, and unnecessary portions were dissolved with a ferric chloride solution. Further, after performing a hole processing for mounting a radiation fin, a plating process was performed to obtain a ceramic circuit board integrated with a base plate. In addition, the said plating is electroless Ni-P;
5 μm, two layers of electroless Ni—B; 2 μm. FIG. 3 shows a sectional view of this state. The amount of warpage at this time was almost 0 μm.

Next, the circuit pattern of the base plate-integrated ceramic circuit board was 12 mm square and 0.4 mm thick.
Was soldered and a thermal cycle test was performed. The condition of the cooling / heating cycle test was -40 ° C;
0 minutes, in air; 10 minutes, 125 ° C .; 30 minutes, in air 10
One minute was one cycle. After 1000 cycles, the presence or absence of cracks in the solder portion under the silicon chip, cracking of the substrate itself, peeling of the circuit, and the like were observed in detail, but no abnormality was found.

Example 2 Silicon carbide powder A (NG-220, manufactured by Taiheiyo Random Co., Ltd., average particle size: 60 μm) 70
g, silicon carbide powder B (GC-1000 manufactured by Yakushima Electric Works Co., Ltd.)
F, 30 g of average particle size: 10 μm) and 10 g of silica sol (Snowtex, manufactured by Nissan Chemical Industries, Ltd.) were weighed and mixed with a stirring mixer for 30 minutes, and then 110 mm × 90 mm × 4.
It was molded at a pressure of 10 MPa into a shape of mm.

The obtained molded body was placed in the air at a temperature of 950 ° C.
For 2 hours to obtain a porous silicon carbide sintered body having a relative density of 65% by volume. Next, the porous silicon carbide sintered body was placed on a 0.7 mm-thick partition plate coated with a release agent, and the mold shown in FIG. 1 (material: carbon Steel) having a 50 × 50 window at the center and having an outer dimension substantially equal to the outer dimension of the porous silicon carbide sintered body.
An oxygen-free copper plate having a thickness of mm was laid up. Next, after inserting a silicon nitride substrate having a characteristic of 100 W / mK of 50 × 50 × 0.4 mm into the window of the oxygen-free copper plate, the outer dimensions of the porous silicon carbide sintered body are substantially equal to those of the porous silicon carbide sintered body. A 0.4 mm thick oxygen-free copper plate was placed on this. In this state, the height of the contents and the frame height become substantially equal. FIG. 4 shows a cross-sectional view in this state. Further, a partition plate coated with a release agent (the same as the above-mentioned partition plate and the size is the same as the outer shape of the mold) is overlapped, and 6
After disposing an iron plate having a thickness of mm, one block was formed.

The subsequent operations were the same as those in Example 1 to obtain a base plate-integrated ceramic circuit board. FIG. 5 shows a cross-sectional view in this state. The surface is Ni-P plating 5
μm, 2 μm of Ni—B plating. The amount of warpage at this time was about 100 μm with a concave circuit surface.

A 12 mm square, 0.4 mm thick silicon chip was soldered to the circuit pattern of the circuit board integrated with the base plate, and the thermal cycle test shown in Example 1 was performed. The occurrence of cracks in the solder portion under the silicon chip, cracks in the substrate, peeling of the circuit, and the like were observed in detail, but no abnormality was observed.

Comparative Example 70 g of silicon carbide powder A (NG-220, manufactured by Taiyo Random Co., average particle size: 60 μm)
Silicon carbide powder B (manufactured by Yakushima Electric Works: GC-1000F,
30 g of an average particle size: 10 μm) and 10 g of silica sol (Snowtex, manufactured by Nissan Chemical Industries, Ltd.) are weighed and mixed with a stirring mixer for 30 minutes, and then 110 mm × 90 mm × 4.6.
50mm x 50mm x 0.6mm on one side of the central part in mm
And was molded at a pressure of 10 MPa.

The obtained molded body was placed in the air at a temperature of 950 ° C.
For 2 hours to obtain a porous silicon carbide sintered body. The relative density of the obtained porous silicon carbide sintered body was 65% by volume.

Next, the obtained porous silicon carbide sintered body was
Placed on a 0.7 mm thick partition plate coated with a release agent,
This was also placed in the mold (material: carbon steel) of FIG. 1 to which a release agent was applied, and 50 × 50 × 0.6
mm W / mK aluminum nitride substrate was inserted. In this state, the frame height is about 0.4m higher than the height of the contents.
m higher. A partition plate coated with a release agent (the same as the above-mentioned partition plate and the size is the same as the outer shape of the mold) was overlaid thereon, and an iron plate having a thickness of 6 mm was arranged on both sides to form one block. At this time, care was taken to ensure that the substrate side was always at the top so that the aluminum nitride substrate placed in the cavity did not come off from the cavity.

Next, the block was pre-heated to a temperature of 1050 ° C. in an electric furnace, and placed in a pre-heated mold, while taking care not to remove the aluminum nitride substrate from the cavity. A molten Cu alloy containing 2% by mass of Si and 0.5% by mass of Ti, which has been heated to a temperature of 1100 ° C., is pressed into the porous silicon carbide sintered body by applying a pressure of 100 MPa for 10 minutes. Impregnated. After cooling the metal mass containing the obtained composite to room temperature,
After cutting with a band saw, the ceramic substrate integrated with the base plate was released from the mold.

Thereafter, the same operation as in Example 1 was performed to obtain a ceramic circuit board integrated with a base plate. FIG. 6 shows a cross-sectional view in this state. The amount of warpage was convex on the circuit side and was about 50 μm.

A 12 mm square, 0.4 mm thick silicon chip was soldered to the circuit pattern of the base plate-integrated ceramic circuit board, and the thermal cycle test shown in Example 1 was performed. Penetration cracks occurred in the ceramic substrate.

[0058]

The ceramic circuit board with integrated base plate of the present invention can be easily manufactured with a high yield.
It is also excellent in mass productivity. And since it has excellent heat dissipation and has a warp amount that is practically acceptable, the power module manufactured using this can be downsized, has high reliability, and An excellent effect that is industrially useful, such as not increasing the thermal resistance even in connection. Furthermore, the electronic device mounting substrate of the present invention is obtained by etching a part of the metal layer on the surface thereof,
The base plate-integrated ceramic circuit board or the like that can be mounted on an electronic device can be easily provided, and is industrially useful.

[Brief description of the drawings]

FIG. 1 is a plan view of a frame material used in an impregnation operation in Examples and Comparative Examples of the present invention.

FIG. 2 is a cross-sectional view illustrating a structure of a base plate-integrated ceramic substrate (substrate for mounting an electronic device) according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view for explaining the structure of the base plate-integrated ceramic circuit board according to the first embodiment of the present invention.

FIG. 4 is a view for explaining the arrangement of each member immediately before impregnation in Embodiment 2 of the present invention.

FIG. 5 is a cross-sectional view for explaining a structure of a ceramic circuit board integrated with a base plate according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a structure of a ceramic circuit board integrated with a base plate according to a comparative example.

[Explanation of symbols]

1: frame material 2: molten metal introduction part (gate) 3: preform storage part 4: metal layer (copper plate) 5: ceramic substrate 6: metal-ceramic composite (Cu-SiC composite) 7: circuit (copper plate) 8 : Copper plate 9: Copper plate 10: Porous inorganic sintered body (preform: Porous silicon carbide sintered body) 11: Impregnating metal (Cu alloy) 12: Circuit (Cu alloy)

Claims (7)

[Claims] 1. A base plate having or not having a concave portion on one main surface, a ceramic substrate disposed on the main surface of the base plate and smaller than the base plate, and the base plate and the ceramic substrate And a metal layer provided so as to cover at least a part of the metal layer, the surface of the metal layer not in contact with the base plate and the ceramics substrate is planar, and the base plate is formed of a metal-metal or a metal. -A carbon or metal-ceramic composite, wherein the metal in the composite and the metal layer are mainly composed of copper, and the purity of the metal layer is higher than the purity of the metal in the composite. Electronic equipment mounting substrate. 2. The electronic device mounting substrate according to claim 1, wherein a plurality of ceramic substrates are provided. 3. A ceramic circuit board integrated with a base plate, wherein a circuit is formed from the metal layer of the board for mounting electronic equipment according to claim 1. 4. A ceramic circuit board integrated with a base plate, comprising: a ceramic circuit board having a circuit on one main surface; and a base plate provided in contact with a main surface of the ceramic circuit board on which no circuit is provided. The height of the circuit surface and the surface of the base plate on which the ceramic substrate is mounted and on which the ceramic substrate is not provided, wherein the base plate is made of a metal-metal composite, a metal-carbon composite, or a metal-ceramic composite; Wherein the metal contained in the circuit and the base plate is mainly copper, and the purity of the metal layer is higher than the purity of the metal in the composite. Circuit board. 5. A porous molded body whose base plate is mainly composed of at least one selected from the group consisting of carbon, silicon carbide, copper oxide, alumina, aluminum nitride, silicon nitride, tungsten and molybdenum. The ceramic circuit board integrated with a base plate according to claim 4, wherein the ceramic circuit board is a composite body impregnated with a metal. 6. Carbon, silicon carbide, copper oxide, alumina,
Aluminum nitride, silicon nitride, tungsten or molybdenum as a main component, a ceramic substrate is disposed on the main surface of the porous molded body having or not having a concave portion on one main surface; A metal plate mainly composed of copper is arranged so as to cover at least a part of the porous molded body and the ceramic substrate together to form a laminate, and the laminate is arranged in a container and mainly composed of copper. Casting a metal, impregnating the voids of the porous molded body with the metal containing copper as a main component, and integrating the porous molded body, a metal plate, and a ceramic substrate, for mounting on an electronic device. Substrate manufacturing method. 7. Carbon, silicon carbide, copper oxide, alumina,
Aluminum nitride, silicon nitride, tungsten or molybdenum as a main component, a ceramic substrate is disposed on the main surface of the porous molded body having or not having a concave portion on one main surface; A metal plate is arranged to cover at least a part of the porous molded body and the ceramic substrate to form a laminate, and the laminate is disposed in a container, and a metal containing copper as a main component is cast, While impregnating the voids of the porous molded body with the metal containing copper as a main component, the porous molded body, the metal plate and the ceramic substrate are integrated, and then formed on the surface of the ceramic substrate opposite to the base plate. Forming a circuit from the metal layer or the metal plate described above.