JP7298988B2 - Ceramic circuit board and its manufacturing method - Google Patents

Description

The present invention relates to a ceramic circuit board and its manufacturing method, and more particularly to a ceramic circuit board suitable for mounting high-power electronic components such as power modules and its manufacturing method.

In recent years, as the performance of industrial equipment such as robots and motors has improved, there has been a demand for inverters with higher current and higher efficiency. Under such circumstances, heat generated from semiconductor elements in power modules used in inverters is increasing. A ceramic circuit board having good thermal conductivity is used to efficiently diffuse heat generated from a semiconductor element.

A power module generally includes a ceramic circuit board, a semiconductor element provided on one side of the ceramic circuit board, and a semiconductor element provided on the other side of the ceramic circuit board by soldering or the like. Equipped with a base plate made of Cu--Mo, Cu--C, Al, Al--SiC, Al--C, or the like, and heat radiating fins provided by screws or the like on the surface of the base plate opposite to the ceramic circuit board. .

Heat generated from a semiconductor element or the like during operation of the power module is transferred to the heat dissipation fins through the ceramic circuit board, solder, and base plate. During actual use, the power module is placed in an environment where heat generation and cooling are repeated. There is a problem that cracks occur in the ceramic substrate due to thermal stress that repeatedly occurs between the ceramic substrate and the metal circuit, resulting in a decrease in reliability.

To address such reliability issues, for example, in a ceramic circuit board having metal layers bonded to both sides of a ceramic substrate, metal layers with different hardness, types, thickness, etc. are used as a metal circuit board and a heat sink, respectively. It has been proposed to join on one side and the other side of a ceramic substrate by using a ceramic substrate (see, for example, Patent Document 1). In addition, when manufacturing a power module, it has been proposed to join the base plate and the ceramic circuit board by bringing the molten base plate and the ceramic circuit board into contact (for example, Patent Document 2). reference).

JP 2004-207587 A JP-A-2002-76551

From the viewpoint of reliability, the ceramic circuit board does not peel off the metal layer from the ceramic base material or cause cracks in the ceramic base material even when repeatedly heated and cooled in actual use. It is desirable to be able to maintain high adhesion of the layers. However, conventional ceramic circuit boards and power modules using the same still have room for improvement during high-temperature operation, and there is also a demand for improved heat dissipation.

The present invention has been made in view of such circumstances, and can maintain high adhesion between the ceramic base material and the metal layer even when used in an environment where heat generation and cooling are repeated, and also has heat dissipation properties. It is an object of the present invention to provide a ceramic circuit board excellent in the resistance and a method for manufacturing the same.

The present invention provides a ceramic circuit board comprising a ceramic substrate and metal layers provided on both sides of the ceramic substrate, wherein the metal layer provided on at least one surface of the ceramic substrate forms a metal circuit. A manufacturing method is provided. This manufacturing method includes (A) forming a first metal layer on both sides of a ceramic substrate by an active metal method, and (B) forming a second metal layer on the surface of the first metal layer by thermal spraying. The metal layer has a multilayer structure including a first metal layer and a second metal layer in this order from the ceramic substrate side and has a thickness of 0.5 to 2.0 mm.

According to the above manufacturing method, by using both the active metal method and the thermal spraying method to form the metal layer, the residual stress in the metal layer can be relaxed, thereby achieving high adhesion between the ceramic substrate and the metal layer. can be realized. In addition, by further forming the second metal layer on the surface of the first metal layer by thermal spraying, it is possible to form a sufficiently thick metal layer with excellent thermal conductivity compared to the ceramic base material, thereby improving heat dissipation. It is possible to obtain a ceramic circuit board excellent in

The present invention provides a ceramic circuit board. This ceramic circuit board comprises a ceramic substrate and metal layers provided on both sides of the ceramic substrate, and the metal layer provided on at least one surface of the ceramic substrate forms a metal circuit. There is, the metal layer has a multilayer structure including a first metal layer and a second metal layer in this order from the ceramic substrate side and has a thickness of 0.5 to 2.0 mm, the first metal layer is formed on both sides of the ceramic substrate by the active metal method, and the second metal layer is formed on the surface of the second metal layer by thermal spraying.

The ceramic circuit board has a metal layer formed by a combination of the active metal method and the thermal spraying method, and as described above, the residual stress in the metal layer is relaxed. It has high adhesion. Moreover, since the second metal layer is further formed on the surface of the first metal layer and the metal layer is sufficiently thick, the heat dissipation is excellent.

The ceramic circuit board according to the present invention may have the following aspects. That is, a ceramic circuit board according to one aspect of the present invention includes a ceramic substrate and metal layers provided on both sides of the ceramic substrate, and the metal layer provided on at least one surface of the ceramic substrate. forms a metal circuit, and the metal layer has a multilayer structure including a first metal layer and a second metal layer in this order from the ceramic substrate side and has a thickness of 0.5 to 2.0 mm wherein the thickness of the first metal layer is in the range of 0.1-0.3 mm and the thickness of the second metal layer is in the range of 0.4-1.9 mm.

In the ceramic circuit board according to the above aspect, for example, the first metal layer is formed by the active metal method and the second metal layer is formed by the thermal spraying method. Since the thickness of the first metal layer, the second metal, and the entire metal layer containing them is within a predetermined range, the ceramic circuit board according to this aspect has excellent adhesion between the ceramic substrate and the metal layer, and heat dissipation. Excellent for

Adhesion between the ceramic substrate and the metal layer can be evaluated by a heat cycle test. In the ceramic circuit board according to the present invention, the operation of leaving the ceramic circuit board in an environment of 180° C. for 30 minutes and then leaving the ceramic circuit board in an environment of -45° C. for 30 minutes is regarded as one cycle, and this cycle is repeated 500 times. It is preferable that the metal circuit does not peel off from the ceramic substrate after repeated heat cycle tests.

The first metal layer and the second metal layer contained in the metal layer preferably contain copper as a main component from the viewpoints of electrical conductivity, thermal conductivity and cost. The term "main component" as used herein means a component contained in an amount of 70% by mass or more based on the total mass of the target metal layer (first metal layer or second metal layer). Preferably, the second metal layer is thicker than the first metal layer. By forming the second metal layer thicker than the first metal layer by thermal spraying, a metal layer having a sufficient thickness and less residual stress can be formed on the surface of the ceramic substrate. The end face of the first metal layer and the end face of the second metal layer may be flush with each other, or the end face of the first metal layer may protrude outside the end face of the second metal layer.

From the viewpoint of mechanical strength, heat resistance, etc., the material of the ceramic substrate is preferably Si ₃ N ₄ . From the viewpoint of heat dissipation of the ceramic circuit board, it is preferable that the ceramic substrate is sufficiently thin, and the thickness thereof is preferably in the range of 0.2 to 1.5 mm.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a ceramic circuit board that can maintain high adhesion between a ceramic substrate and a metal layer and has excellent heat dissipation even when used in an environment where heat generation and cooling are repeated, and a method for manufacturing the same. be.

1 is a cross-sectional view showing an embodiment of a ceramic circuit board; FIG. FIG. 4 is a cross-sectional view showing another embodiment of a ceramic circuit board; It is a sectional view showing one mode of a power module.

Several embodiments of the invention are described in detail below. However, the present invention is not limited to the following embodiments.

<Ceramic circuit board>
FIG. 1 is a cross-sectional view showing one embodiment of a ceramic circuit board. As shown in FIG. 1, a ceramic circuit board 10A includes a ceramic base 1 and metal layers 2 and 3 provided on both sides of the ceramic base 1. As shown in FIG. At least one of the metal layers 2 and 3 forms an electric circuit (metal circuit). In this embodiment, the metal layer 2 forms an electrical circuit (see FIG. 3). The metal layer 2 has a multilayer structure including a first metal layer 2a and a second metal layer 2b in this order from the ceramic substrate 1 side. The metal layer 3 has a multilayer structure including a first metal layer 3a and a second metal layer 3b in this order from the ceramic substrate 1 side.

The metal layers 2 and 3 preferably contain Cu (copper) as a main component. The term "main component" as used herein means a component that is contained in an amount of 70% by mass or more based on the total mass of the metal layers 2 and 3 . The content of Cu in the metal layers 2 and 3 may be 90% by mass or more, or may be 95% by mass or more. Mo, C, etc. are mentioned as elements other than Cu which the metal layers 2 and 3 may contain. The metal layers 2 and 3 may contain Al (aluminum) as a main component. The Al content in the metal layers 2 and 3 may be 90% by mass or more, or may be 95% by mass or more. Elements other than Al that the metal layers 2 and 3 may contain include Si, C, and the like. The metal layers 2 and 3 may contain trace amounts of unavoidable impurities. The metal layers 2 and 3 (the first metal layers 2a and 3a and the second metal layers 2b and 3b) need not have the same composition.

The first metal layers 2a and 3a are formed on the surface of the ceramic substrate 1 by the active metal method. On the other hand, the second metal layers 2b, 3b are formed on the surfaces of the first metal layers 2a, 3a by thermal spraying. By using both the active metal method and the thermal spraying method to form the metal layers 2 and 3, the residual stress in the metal layers 2 and 3 can be relaxed. High adhesion can be achieved. Since the metal layers 2 and 3 are sufficiently thick, the metal layers 2 and 3 can sufficiently secure the mechanical strength of the ceramic circuit board 10A, and the relatively thin ceramic base 1 can be adopted. heat dissipation can be achieved.

Even if the ceramic circuit board 10A having the above configuration is used in an environment in which heat cycles, heat generation, and cooling are repeatedly performed during the manufacture of power modules, cracks may occur in the ceramic base 1, and metal may be dislodged from the ceramic base 1. Problems such as peeling of the layers 2 and 3 can be sufficiently suppressed. The inventors of the present invention consider the reason for this as follows.

First, according to the studies of the present inventors, the occurrence of cracks in the ceramic base material and the separation of the ceramic base material and the metal layer due to the heat cycle during the manufacture of the power module are caused by the ceramic base material and the metal layer constituting the ceramic circuit board. It has been found that the cause is the difference in the linear thermal expansion coefficients of the In general, the coefficient of linear thermal expansion of the metal layer is larger than the coefficient of linear thermal expansion of the ceramic substrate. Therefore, tensile stress remains in the metal layer when the temperature at which the ceramic substrate and the metal layer are bonded is returned to room temperature or due to heat cycles. It is considered that the residual tensile stress (residual stress) causes the problems described above.

In order to reduce the residual stress, the inventors of the present invention have focused on the point that the difference in linear thermal expansion coefficient between the ceramic base material and the metal layer can be changed by using different bonding methods when forming the metal layer. . According to further studies by the inventors of the present invention, the coefficient of linear thermal expansion of the ceramic circuit board depends on the structure (thickness, etc.) and composition of the ceramic base and metal layer, It has been found that the residual stress generated by the difference in thermal expansion between the two materials when returning from the temperature at which the two are joined to room temperature. For this reason, for example, ceramic circuit boards having the same structure may have different coefficients of linear thermal expansion depending on the joining method. In general, the ceramic base material and the metal layer are often joined by brazing by the active metal method at a temperature of about 800 ° C. When joining under such conditions, the process of cooling to room temperature after joining Tensile stress remains in the metal layer with a large coefficient of linear thermal expansion.

On the other hand, when a metal layer is formed by thermal spraying at a relatively low temperature, it is known that compressive stress remains in the metal layer. Furthermore, the inventors have found that residual stress can be alleviated by laminating metal layers. Especially in power modules that operate at high temperatures, the temperature difference becomes large, so it was not possible to increase the thickness of the metal layer to ensure heat dissipation with conventional substrates. A highly reliable substrate can be obtained. The details of the method for joining the ceramic base material and the metal layer will be described later.

In order to obtain such a ceramic circuit board 10A, _the ceramic base 1 is preferably made of _Si3N4 , for example.

The thickness of the ceramic substrate 1 is preferably 0.2-1.5 mm, more preferably 0.25-1.0 mm. If the thickness of the ceramic substrate 1 is less than 0.2 mm, the thermal shock resistance tends to be lowered, and if it exceeds 1.5 mm, the heat dissipation tends to be lowered.

The second metal layers 2b, 3b are preferably thicker than the first metal layers 2a, 3a. By forming the second metal layers 2b and 3b formed by the thermal spraying method to be thicker than the first metal layers 2a and 3a formed by the active metal method, the metal layers have sufficient thickness and less residual stress. 2 and 3 can be formed on the surface of the ceramic substrate 1 .

The thickness of each of the first metal layers 2a and 3a is, for example, in the range of 0.1 to 0.3 mm, preferably in the range of 0.11 to 0.2 mm, and more preferably 0.12 to 0.15 mm. is more preferably in the range of When the thickness of the first metal layers 2a and 3a is less than 0.1 mm, it tends to be difficult to form the first metal layers 2a and 3a. As a result, residual stress increases and reliability decreases. The thicknesses of the first metal layers 2a and 3a may be substantially the same or different, but are preferably substantially the same from the viewpoint of facilitating the manufacture of the ceramic circuit board 10A.

The thickness of each of the second metal layers 2b and 3b is, for example, in the range of 0.4 to 1.9 mm, preferably in the range of 0.8 to 1.5 mm, and 1.0 to 1.3 mm. is more preferably in the range of If the thickness of the second metal layers 2b and 3b is less than 0.4 mm, the effect of relieving residual stress tends to be insufficient. It tends to take a long time to form the metal layers 2b and 3b. The thicknesses of the second metal layers 2b and 3b may be substantially the same or different, but are preferably substantially the same from the viewpoint of facilitating the manufacture of the ceramic circuit board 10A.

The metal layers 2 and 3 have a multi-layer structure including first metal layers 2a and 3a and second metal layers 2b and 3b in this order from the ceramic substrate 1 side. Each of the metal layers 2 and 3 has a thickness of 0.5 to 2.0 mm, preferably 1.0 to 1.8 mm. If the thickness of the metal layer 2 forming the electric circuit is less than 0.5 mm, the current that can flow is limited. As shown in FIG. 3, if the thickness of the metal layer 3 bonded to the base plate 20 via the first solder 21 is less than 0.5 mm, the heat radiation of the ceramic circuit board 10A will be insufficient. Become. On the other hand, when the thickness of the metal layers 2 and 3 exceeds 2.0 mm, the thermal shock resistance becomes insufficient. The thicknesses of the metal layers 2 and 3 may be substantially the same or different, but are preferably substantially the same from the viewpoint of facilitating the manufacture of the ceramic circuit board 10A.

The ceramic circuit board 10A is heated by repeating this cycle 500 times, with one cycle consisting of leaving the ceramic circuit board 10A in an environment of 180° C. for 30 minutes and then leaving the ceramic circuit board 10A in an environment of −45° C. for 30 minutes. It is preferable that the metal layers 2 and 3 do not separate from the ceramic substrate 1 after the cycle test.

<Method for producing ceramic circuit board>
Next, a method for manufacturing the ceramic circuit board 10A will be described. The manufacturing method according to the present embodiment includes (A) a step of forming the first metal layers 2a and 3a on both surfaces of the ceramic substrate 1 by an active metal method, and (B) the surface of the first metal layers 2a and 3a and forming the second metal layers 2b, 3b by thermal spraying.

According to the above manufacturing method, by using both the active metal method and the thermal spraying method to form the metal layers 2 and 3, the residual stress in the metal layers 2 and 3 can be relaxed. and high adhesion of the metal layers 2 and 3 can be realized. In addition, by further forming the second metal layers 2b, 3b on the surfaces of the first metal layers 2a, 3a by thermal spraying, the metal layers 2, 3 having excellent thermal conductivity compared to the ceramic substrate 1 can be formed sufficiently. It is possible to form the ceramic circuit board 10A with an excellent heat dissipation property. The first metal layers 2a and 3a serve as base layers for the second metal layers 2b and 3b formed by thermal spraying. When the first metal layers 2a and 3a are not formed on the surface of the ceramic substrate 1 and the metal layers are directly formed on the surface of the ceramic substrate 1 by thermal spraying, the melting point or softening point of the sprayed metal powder may be In some cases, the metal powder does not sufficiently adhere to the ceramic substrate 1 (see Comparative Example 5).

The active metal method includes a step of bonding metal plates to both sides of the ceramic substrate 1 using a brazing material. The thickness and composition of the metal plates to be joined may be selected according to the thickness and composition of the first metal layers 2a and 3a to be formed. The temperature condition for joining is, for example, in the range of 780 to 810° C., and an appropriate temperature may be set according to the type of brazing material used.

When joining a metal plate containing Cu (Cu plate) to the ceramic substrate 1, for example, Ag (90%)-Cu (10%)-TiH ₂ (3.5%) brazing material is used at a temperature of 800 A Cu plate is bonded to both surfaces of the ceramic substrate 1 at ℃. When joining a metal plate containing Al (Al plate), for example, an Al--Cu--Mg clad foil is used as a brazing material, and the Al plates are joined to both sides of the ceramic substrate 1 at a temperature of 630.degree.

The thermal spraying method (also referred to as “cold spray method”) is a method in which metal powder of 10 to 270° C. (preferably 20 to 260° C.) is directed to the surface of the first metal layers 2a, 3a at 250 to 1050 m/ Spraying at a speed of seconds (preferably 400-1000 m/s). Depending on the composition of the second metal layers 2b, 3b to be formed, the composition of the metal powder to be sprayed may be selected, and the temperature conditions and spraying speed may be set. The amount of sprayed metal powder may be adjusted according to the thickness of the second metal layers 2b and 3b. A spray gun, for example, may be used to spray the metal powder. Nitrogen, for example, is used as working gas for injecting the metal powder.

After forming the first metal layers 2a and 3a by the active metal method and before forming the second metal layers 2b and 3b by the thermal spraying method, at least one of the first metal layers 2a and 3a is etched to form a circuit pattern. may be formed. In this case, the second metal layer may be formed by thermal spraying while a mask material having openings corresponding to this circuit pattern is placed on the surface of the ceramic substrate 1 . By using the mask material, the second metal layer can be formed only at desired locations. Electroless Ni plating or the like may be applied to the surface of the second metal layer.

In the ceramic circuit board 10A according to the present embodiment, as shown in FIG. 1, the end faces 2c, 3c of the first metal layers 2a, 3a and the end faces 2d, 3d of the second metal layers 2b, 3b are flush with each other. . From the viewpoint of achieving better thermal shock resistance of the ceramic circuit board, as in the ceramic circuit board 10B shown in FIG. It may protrude outside the end faces 2d and 3d, that is, on the end side of the ceramic substrate 1. As shown in FIG. The width of the portion where the end surfaces 2c and 3c protrude from the end surfaces 2d and 3d is, for example, 1 to 1000 μm.

<Power module>
FIG. 3 is a cross-sectional view showing one embodiment of the power module. As shown in FIG. 3, the power module 50 includes a base plate 20, a ceramics circuit board 10 bonded onto the base plate 20 via a first solder 21, and a second solder 22 on the ceramics circuit board 10. and a semiconductor element 6 that is joined via the . The ceramic circuit board 10 is a ceramic circuit board 10A or a ceramic circuit board 10B, and the metal layer 2 forms an electric circuit (metal circuit). The metal layer 3 may or may not form a metal circuit.

The base plate 20 is joined to the metal layer 3 via the first solder 21 . The semiconductor element 6 is bonded to a predetermined portion of the metal layer 2 via a second solder 22, and is also bonded to a predetermined portion of the metal layer 2 with a metal wire 7 such as an aluminum wire (aluminum wire). there is Each of the components provided on the base plate 20 is covered with, for example, a hollow box-shaped resin housing 25 with one side open and housed in the housing 25 . A hollow portion between the base plate 20 and the housing 25 is filled with a filler 28 such as silicone gel. An electrode 9 penetrating the housing 25 is joined to a predetermined portion of the metal layer 2 via a third solder 23 so as to be electrically connected to the outside of the housing 8 .

An edge of the base plate 20 is formed with a mounting hole 20a for screwing a heat radiating component to the power module 50, for example. The number of mounting holes 20a is, for example, four or more. At the edge of the base plate 20, instead of the mounting hole 20a, a mounting groove may be formed so that the side wall of the base plate 20 has a U-shaped cross section.

Since the power module 50 includes the ceramic circuit board according to the present embodiment described above, it can be suitably used as a drive inverter for trains or automobiles in which high withstand voltage, high output, etc. are required.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples. However, the present invention is not limited to these examples.

(Example 1)
A silicon nitride (Si ₃ N ₄ ) substrate (size: 50 mm×60 mm×0.32 mmt) was used as a ceramic substrate. Cu plates (thickness: 0.1 mm) were bonded to both sides of the ceramic substrate at a temperature of 800° C. using Ag—Cu—TiH ₂ brazing material (step (A)). Subsequently, a Cu circuit (second metal layer) having a thickness of 0.9 mm was laminated by a thermal spray method (cold spray method) under the following conditions ((B) step). After the obtained laminate was annealed at a temperature of 300° C., the surface of the Cu circuit was subjected to electroless Ni plating, thereby obtaining a ceramic circuit board according to this example. The "Cu circuit" in this example is formed on the entire surface of the ceramic substrate.
<Conditions of thermal spraying method>
・Temperature of Cu powder: 260°C
・Cu powder spraying speed: 800 m / sec ・Working gas: nitrogen

(Examples 2-5)
A silicon nitride (Si ₃ N ₄ ) substrate having a thickness shown in Table 1 is used, and a Cu circuit (second metal layer) having a thickness shown in Table 1 is formed by thermal spraying (cold spraying). A ceramic circuit board was produced in the same manner as in Example 1 except that the substrate was formed.

(Comparative Examples 1 to 3)
A silicon nitride (Si ₃ N ₄ ) substrate having a thickness shown in Table 1 is used, and a Cu circuit (second metal layer) having a thickness shown in Table 1 is formed by thermal spraying (cold spraying). A ceramic circuit board was produced in the same manner as in Example 1 except that the substrate was formed.

(Comparative Example 4)
A silicon nitride (Si ₃ N ₄ ) substrate (size: 50 mm×60 mm×0.32 mmt) was used as a ceramic substrate. A Cu plate (thickness: 0.5 mm) was joined to both sides of the ceramic substrate at a temperature of 800° C. using Ag—Cu—TiH ₂ brazing material. Electroless Ni plating was applied to the surface of the Cu plate to produce a ceramic circuit board.

(Comparative Example 5)
A silicon nitride (Si ₃ N ₄ ) substrate (size: 50 mm×60 mm×0.32 mmt) was used as a ceramic substrate. An attempt was made to form a Cu circuit on the surface of the silicon nitride substrate by thermal spraying (cold spray method), but the sprayed Cu particles did not adhere to the surface of the silicon nitride substrate.

<Apparent Thermal Conductivity of Ceramic Circuit Board>
The apparent thermal conductivity of the ceramic circuit substrates according to Examples 1 to 5 and Comparative Examples 1 to 4 was determined as follows using a NETZSCH flash analyzer (LFA467). The thermal diffusivity of the blackened sample (ceramic circuit board) was measured at a flash voltage of 200V. The apparent thermal conductivity of the sample was calculated using this measured value and the apparent density and apparent specific heat capacity calculated from the thickness of each layer and the sample size by the law of addition. The physical properties of silicon nitride and Cu are given below. Table 1 shows the results.
Silicon nitride (Si ₃ N ₄ ): density 3.2 g/cm ³ , specific heat capacity 0.68 J/g·K
Cu: density 8.89 g/cm ³ , specific heat capacity 0.389 J/g·K

<Heat cycle test>
The following heat cycle tests were performed on the ceramic circuit boards according to Examples 1-5 and Comparative Examples 1-4. A heat cycle test was performed for 500 cycles, with one cycle consisting of leaving the sample (ceramic circuit board) in an environment of 180° C. for 30 minutes and then leaving the sample in an environment of −45° C. for 30 minutes. After the heat cycle test, the presence or absence of an abnormality (peeling of the metal circuit) of the sample was visually confirmed. Table 1 shows the results.

DESCRIPTION OF SYMBOLS 1... Ceramics base material 2, 3... Metal layer 2a, 3a... First metal layer 2b, 3b... Second metal layer 2c, 3c... End surface of first metal layer 2d, 3d... Second metal layer , 10A, 10B... Ceramic circuit board.

Claims (7)

a ceramic base material having a thickness of 0.2 to 1.5 mm;
metal layers provided on both sides of the ceramic base;
with
A method for manufacturing a ceramic circuit board, wherein the metal layer provided on at least one surface of the ceramic substrate forms a metal circuit,
(A) forming a first metal layer having a thickness of 0.1 to 0.3 mm on both sides of the ceramic substrate by an active metal method;
(B) forming a second metal layer on the surface of the first metal layer by a cold spray method;
including
The metal layer has a multilayer structure including the first metal layer and the second metal layer in this order from the ceramic substrate side, and has a thickness of 0.5 to 2.0 mm. Production method. 2. The method of manufacturing a ceramic circuit board according to claim 1, wherein said first metal layer and said second metal layer are mainly composed of copper. 3. The method of manufacturing a ceramic circuit board according to claim 1, wherein said second metal layer is thicker than said first metal layer. a ceramic base material having a thickness of 0.2 to 1.5 mm;
metal layers provided on both sides of the ceramic base;
with
A ceramic circuit board in which the metal layer provided on at least one surface of the ceramic substrate forms a metal circuit,
The metal layer has a multilayer structure including a first metal layer and a second metal layer in this order from the ceramic substrate side and has a thickness of 0.5 to 2.0 mm,
The first metal layer has a thickness in the range of 0.1 to 0.3 mm and is formed on both sides of the ceramic substrate by an active metal method, and the second metal layer is the first metal layer. A ceramic circuit board formed by a cold spray method on the surface of the After leaving the ceramic circuit board in an environment of 180° C. for 30 minutes and then leaving the ceramic circuit board in an environment of −45° C. for 30 minutes as one cycle, this cycle is repeated 500 times. After a heat cycle test,
5. The ceramic circuit board according to claim 4 , wherein the metal circuit does not separate from the ceramic substrate. 6. The ceramic circuit board according to claim 4 , wherein said ceramic substrate is made of Si ₃ N ₄ and has a thickness of 0.2 to 1.5 mm. 5. The end face of the first metal layer and the end face of the second metal layer are flush with each other, or the end face of the first metal layer protrudes outside the end face of the second metal layer. 7. The ceramic circuit board according to any one of 6 .

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