JP5485127B2 - Manufacturing method of ceramic circuit board - Google Patents

Description

  The present invention relates to a ceramic substrate, a manufacturing method thereof, and a ceramic circuit substrate.

  Conventionally, circuit boards in which a metal circuit layer is provided on a ceramic substrate have been widely used. In particular, a ceramic circuit board in which a metal plate such as copper or aluminum is provided on a substrate made of a ceramic sintered body mainly composed of a compound such as aluminum nitride, silicon nitride, alumina, alumina and zirconia has excellent electrical insulation. For example, it is used for a module substrate on which an electronic component such as a power transistor is mounted.

  As a method for cost reduction and manufacturing a small circuit board for manufacturing such a ceramic circuit board, a method of obtaining a large ceramic sintered body and dividing it into a plurality of parts (so-called “multi-cavity”) Method). For example, by forming a break groove in a ceramic molded body called a green sheet and sintering it to produce a ceramic sintered body, or dividing the ceramic sintered body along the break groove, or ceramic sintering The ceramic sintered body is produced, and then a break groove is formed in the ceramic sintered body, and then the ceramic sintered body is divided along the break groove to obtain a large number of pieces.

  In order to take a large number of pieces, it is necessary to form a break groove on the surface of the ceramic sintered body for easy division. Conventionally, as a break groove, there are a method of providing a groove in a line shape with a jig such as a knife cutter (scribe line type), a method of continuously providing small holes by a laser processing method (scribe dot type), and the like. In either method, the break groove is generally formed only on one surface of the ceramic substrate.

  When this break groove is shallow, there are problems such as burrs occurring in the divided ceramic substrate, and it is difficult to obtain a ceramic substrate having a desired size and shape due to a break defect. From this, it can be said that the deeper the break groove, the easier the dividing operation of the ceramic substrate and the better divided cross section can be obtained. However, forming a deep break groove leads to an increase in time and cost, and handling of the ceramic molded body before division becomes difficult, so it cannot be said that it is satisfactory in terms of handling properties. For example, when a break groove is formed in a ceramic sintered body, laser processing or knife cutter processing is generally performed, but forming a deep break groove by these is disadvantageous in terms of time and cost. In addition, when a break groove is formed in a green sheet, it is considered that the handling property is remarkably deteriorated and the sheet is deformed or divided during handling of the sheet, or cracks are generated in the subsequent sintering process. It is done. In the case of a thick ceramic substrate, the above problem becomes remarkable.

  The present invention solves the above-described problems, and provides a ceramic substrate excellent in handling properties and excellent splitting property free from burrs by forming appropriate break grooves on both sides of the substrate. It is.

  Therefore, the ceramic substrate according to the present invention is characterized in that there is a substantially convex step on at least one side surface of the ceramic substrate.

  Another ceramic substrate according to the present invention is a ceramic substrate obtained by dividing a ceramic sintered body along break grooves formed in the ceramic sintered body, and is at least one of the ceramic substrates. One side surface is formed with a notch portion derived from the break groove at an upper end portion and a lower end portion of the side surface.

  A ceramic circuit board according to the present invention is characterized in that a metal plate is provided on the ceramic substrate.

  In the method for manufacturing a ceramic substrate according to the present invention, a break groove is formed in a sheet-like ceramic molded body, and then sintered to produce a ceramic sintered body, and the ceramic sintered body is formed along the break groove. A method of manufacturing a ceramic substrate by dividing a body, wherein the break grooves are formed on an upper surface and a lower surface of the ceramic molded body.

  Furthermore, in the method for manufacturing a ceramic substrate according to the present invention, a ceramic sintered body is produced by sintering a sheet-like ceramic molded body, and then a break groove is formed before or after the sintering of the ceramic sintered body. Then, a method of manufacturing the ceramic substrate by dividing the ceramic sintered body along the break grooves, wherein the break grooves are formed on the upper surface and the lower surface of the ceramic sintered body. It is.

  According to the present invention, it is possible to obtain a ceramic substrate that has good handling properties, can suppress the occurrence of burrs and the like, and has excellent splitting properties.

Sectional drawing which shows an example of the ceramic substrate of this invention.

  The ceramic substrate according to the present invention is a ceramic substrate obtained by dividing a ceramic sintered body along break grooves formed in the ceramic sintered body, and the ceramic substrate is formed on at least one side surface of the ceramic substrate. The notch part derived from the break groove is formed in the upper end part and lower end part of this side surface, It is characterized by the above-mentioned.

  The side surface of the ceramic substrate according to the present invention on which the cut-out portion is provided is formed by dividing a large number of pieces. Therefore, when only one side surface of the ceramic substrate is formed by division, only one side surface is formed. When two side surfaces of the ceramic substrate are formed by division, three side surfaces of the ceramic substrate or two side surfaces are formed. In the case where the four side surfaces are formed by division, a ceramic substrate having notches on the three or four side surfaces is obtained.

Hereinafter, the present invention will be described in detail with reference to the drawings as necessary.
FIG. 1 is a cross-sectional view showing an example of a ceramic substrate according to the present invention. On the side surface 2 of the ceramic substrate 1 shown in FIG. 1, a notch a and a notch b derived from a break groove formed for division are formed. Since the ceramic substrate 1 of the present invention has the cutout portion A and the cutout portion B at the upper end portion and the lower end portion, a substantially convex step is formed in the cross section on at least one side surface.

  In the notch portion A formed at the lower end portion of the side surface 2, the lateral width is A1, the length in the cross-sectional direction of the ceramic substrate is B1, and in the notch portion B formed at the upper end portion of the side surface 2, the lateral width is A2. The length of the ceramic substrate in the cross-sectional direction is B2.

When the groove shape of the break groove is the right and left object and the break groove is formed at right angles to the substrate, the lateral width A2 is approximately half the size of the break groove, and the length of the notch portion B in the cross-sectional direction of the ceramic substrate The length B2 substantially corresponds to the depth of the break groove.
This notch is derived from the break groove formed for division, and the surface of this notch corresponds to the surface on one side of the groove inner wall surface of the break groove. In addition, the lateral width A2 is approximately half the size of the break groove, and the length B2 of the notch portion B in the cross-sectional direction of the ceramic substrate substantially corresponds to the depth of the break groove. Similarly, the width A1 of the notch a is approximately half the size of the break groove, and the length B1 of the notch i in the cross-sectional direction of the ceramic substrate substantially corresponds to the depth of the break groove. . Further, the shapes of the notch portion b and the notch portion i substantially correspond to the shape of the break groove.

  Whether or not the notch portion in the side surface portion of the ceramic substrate is derived from the break groove depends on the surface roughness (Ra) of the notch portion and the surface roughness (Ra) of the side surface portion that is not the notch portion. It can be determined. For example, the notch portion is provided before or after sintering, while the side surface portion that is not the notch portion retains the shape of the divided fracture surface, or the side surface is polished. The surface roughness (Ra) of the part is different.

  In FIG. 1, the thickness of the ceramic substrate is indicated by T. The thickness T of the ceramic substrate varies depending on the specific use and purpose of the ceramic substrate, but in the present invention, it is effective when the ceramic substrate is relatively thick, particularly when T is 0.6 to 2.0 mm. is there.

  When the thickness of the ceramic substrate is as thin as less than 0.6 mm, it is sufficiently easy to divide even if the break groove is provided only on one side. On the other hand, if the thickness exceeds 2.0 mm, the strength of the ceramic substrate is high, so even if break grooves are provided on both sides, it is difficult to divide, and breakage is likely to occur. When the thickness exceeds 2.0 mm, it is preferable not to take a large number of pieces.

  The sum of the length B2 in the cross-sectional direction of the ceramic substrate of the cutout portion B and the length B1 in the cross-sectional direction of the ceramic substrate of the cutout portion B is 1/2 of the thickness T of the ceramic substrate. It is preferable that it is as follows, and it is preferable that it is 1/4 or more [(1/4) T ≦ (B1 + B2) ≦ (1/2) T]. When the sum of B1 and B2 exceeds 1/2 of T, handling properties are poor and it is difficult to stably divide the ceramic substrate. When the sum of B1 and B2 is less than 1/4 of T, a large force is required for the division, and burrs are generated during the division, and a ceramic substrate having a desired size and shape is obtained. Problems such as being difficult to be generated occur.

  The lengths B2 and B1 in the cross-sectional direction of the substrate at the notches A and B may be the same or different.

  Similarly, the widths A2 and A1 at the notches A and B may be the same or different.

  The lateral width A2 and the lateral width A1 vary depending on the method of forming the break groove, but in the present invention, each is preferably in the range of 0.01 to 0.3 mm. The width A2 and width A1 are about 0.01 to 0.05 mm when a break groove is formed in a ceramic sintered body with a knife cutter, and usually about 0.1 to 0.5 mm when formed by laser processing. Is preferred. When the break groove is formed in the green sheet (ceramic formed body), it is preferable that the thickness is about 0.05 to 0.1 mm in consideration of shrinkage of the formed body after sintering.

  The ceramic substrate according to the present invention only needs to be formed with a predetermined notch in at least a part of its side surface. Accordingly, the present invention is not limited to the one in which the notch portion A and the notch portion B are provided continuously and uniformly from the end to the end of the side surface of the ceramic substrate. For example, the laser irradiation is intermittently performed on both surfaces of the substrate, and after forming a large number of spot-shaped (dot-shaped) laser processing holes, the side-shaped ceramic substrate formed by dividing is also used. The present invention is intended to include.

  The ceramic substrate 1 according to the present invention can be formed from various ceramic substrate materials generally used conventionally. For example, it can be preferably formed from a substrate material containing as a main component at least one of aluminum nitride, silicon nitride, alumina, and a compound of alumina and zirconia. Among these, those formed from a substrate material mainly composed of aluminum nitride are preferable from the viewpoint of thermal conductivity, and those formed from a substrate material mainly composed of silicon nitride are preferable from the viewpoint of strength and the like. Such a ceramic substrate material can contain various rare earth compounds, preferably, for example, oxides of yttrium, ytterbium, erbium, cerium, and the like as a sintering aid, if necessary. In the present invention, the type of rare earth compound and the amount of addition thereof that are particularly preferable can be determined according to the type of ceramic substrate material, the required performance of the ceramic circuit board, and the like. For example, when obtaining a ceramic substrate mainly composed of aluminum nitride and having high thermal conductivity, it is preferable to use 2 to 5% by mass of yttrium oxide as a sintering aid. For example, when obtaining a ceramic substrate having silicon nitride as a main component and particularly high mechanical properties, a total of 2 to 17% by mass of at least one of yttrium oxide, erbium oxide, and ytterbium oxide is used as a sintering aid. It is preferable to do.

  In the present invention, a predetermined characteristic can be obtained even with one kind of rare earth compound as a sintering aid, but it goes without saying that a combination of a plurality of sintering aids is not excluded. Moreover, you may add blackening materials, such as a metal element and a compound of Ti, Hf, Zr, W, Mo, and Cr, as needed.

  The ceramic raw material powder and the sintering aid can be mixed according to a conventional method. In the present invention, the ceramic raw material powder can be mixed with the sintering aid or the like using, for example, a ball mill. In mixing, various auxiliary materials can be blended as necessary. In the present invention, auxiliary materials conventionally used in the production of this type of ceramic substrate, for example, various carbonaceous substances that act as binders can be blended. Preferable specific examples of such a carbonaceous material include organic binders such as acrylic resins.

  The mixture of the ceramic raw material powder, the sintering aid powder, and the auxiliary material blended as necessary is then formed into a sheet by, for example, a general-purpose die press method or a doctor blade method.

  The ceramic substrate according to the present invention can be manufactured by various methods. Preferably, for example, after a break groove is formed in a sheet-like ceramic molded body (green sheet), this is sintered to produce a ceramic sintered body, and the ceramic sintered body is divided along the break groove. The ceramic substrate can be manufactured by forming the break grooves on the upper surface and the lower surface of the ceramic molded body.

Alternatively, a ceramic sintered body is produced by sintering a sheet-like ceramic molded body, and then a break groove is formed in the ceramic sintered body, and then the ceramic sintered body is divided along the break groove to obtain a ceramic. A method of manufacturing a substrate, which can be manufactured by forming the break grooves on an upper surface and a lower surface of the ceramic sintered body.
The shape of the break groove is arbitrary. For example, the cross section can be substantially V-shaped or U-shaped.

  The sheet-like molded body is sintered after being subjected to a degreasing step as necessary. The degreasing step is preferably, for example, 300 to 800 ° C x 0.5 to 5 hours. The temperature and processing time of the degreasing step can be appropriately selected according to the size and type of the ceramic substrate. The sintering temperature is preferably in the range of 1600-1950 ° C. The sintering time is preferably in the range of 0.5 to 10 hours. Sintering temperature and sintering time are based on the shape and size of the compact, density of the compact, strength and hardness of the fired body, specific applications, and the relationship with the sintering temperature and sintering time. The most appropriate condition within the above range can be specifically determined.

The ceramic sintered body obtained as described above can be divided into a predetermined size and shape. In the case where the break groove is formed at the green sheet stage, the ceramic sintered body can be divided by applying a stress along the break groove. When the break groove is not yet formed, the break groove can be formed by forming a break groove in a linear or dot shape in the ceramic sintered body by, for example, laser processing or the like, and applying a stress along this.
In this way, the ceramic substrate according to the present invention can be manufactured.

  The ceramic substrate according to the present invention can be provided with a metal plate on at least a part of one side or both sides thereof. The metal plate may be patterned so that a desired electric circuit is formed on the substrate. A ceramic substrate provided with a metal plate so as to form such an electric circuit is a particularly preferred specific example of the present invention. Here, either division of the ceramic sintered body or installation of the metal plate (formation or lamination of the metal plate) may be performed first. That is, the metal plate can be divided after being installed, or the metal plate can be installed after being divided. Further, the installation of the metal plate can be divided into a plurality of times, and after forming a part of the circuit, it can be divided and then the remaining circuit can be installed.

  When the metal circuit board is provided on the ceramic substrate, it is preferable to provide the metal circuit board toward the notch portion having a short length in the cross-sectional direction of the substrate. That is, in the case of B2 <B1, it is preferable to provide the metal circuit board toward the notch portion (b) whose length in the cross-sectional direction of the substrate is short.

  The metal plate that has been generally used can be used. In the present invention, it is possible to use copper, aluminum, silver, gold, nickel, chromium, zinc, lead, tin, platinum, and a metal formed from any one of the above metal compounds. Among the above, it is particularly preferable to use a metal plate formed of a metal mainly composed of at least one of copper and aluminum.

  The metal plate can be bonded to the ceramic substrate by an active metal method or a direct bonding method. In addition to the form in which the metal plates are joined, the circuit can be formed by a thick film method using paste or a thin film method using sputtering or the like.

  Such a ceramic substrate and a ceramic circuit board according to the present invention have excellent mechanical strength and shape stability, and are excellent in handling at the time of manufacture, and thus are suitable for various applications. . In particular, it is suitable for a module substrate on which an electronic component such as a power transistor is mounted.

<Example 1>
A ceramic sintered body shown in Table 1 was prepared by sintering aluminum oxide powder as a main component and adding 4% by mass of yttrium oxide as a sintering aid as a ceramic raw material. As shown in Table 1, break grooves were formed on both surfaces of the ceramic sintered body. The ceramics were divided along the break grooves to obtain multiple pieces. The size of the ceramic substrate after the division was unified to 10 mm × 20 mm, and the number of multiple pieces was unified to 16 pieces (4 × 4 pieces).

  The “knife cutter method” is a method of forming a break groove, in which a ceramic molded body is provided with a scribe line with a jig such as a knife cutter, and the “laser method” is provided with a scribe dot by laser processing on a ceramic sintered body. Is the method. In this embodiment, the cross section of the scribe groove formed by the knife cutter was U-shaped, and the cross section of the scribe groove formed by laser processing was V-shaped.

  From the results when 100 similar ceramic sintered bodies were prepared and divided under the same conditions as described above, the break defect rate (the ratio of the number of ceramic substrates in which break defects occurred in 100 ceramic sintered bodies) ). The results were as shown in Table 1.

<Example 2>
A ceramic sintered body shown in Table 1 was prepared by sintering aluminum nitride powder as a main component and adding 3% by mass of yttrium oxide as a sintering aid as a ceramic raw material. As shown in Table 1, break grooves were formed on both surfaces of the ceramic sintered body.
Multiple pieces were taken and divided in the same manner as in Example 1, and the break defect rate was similarly determined. The results were as shown in Table 1.

<Example 3>
A ceramic raw material containing silicon nitride powder as a main component and 4% by mass of yttrium oxide, 3% by mass of erbium oxide and 1% by mass of titanium oxide as a sintering aid was used as a ceramic raw material, and this was sintered. The ceramic sintered body shown in FIG. As shown in Table 1, break grooves were formed on both surfaces of the ceramic sintered body.
Multiple pieces were taken and divided in the same manner as in Example 1, and the break defect rate was similarly determined. The results were as shown in Table 1.

<Example 4>
A ceramic sintered body shown in Table 1 was manufactured by sintering a ceramic raw material containing zirconium oxide powder as a main component and adding 5% by mass of yttrium oxide as a sintering aid. As shown in Table 1, break grooves were formed on both surfaces of the ceramic sintered body.
Multiple pieces were taken and divided in the same manner as in Example 1, and the break defect rate was similarly determined. The results were as shown in Table 1.

<Comparative Example 1>
Except that the break grooves were formed only on one side of the ceramic sintered body, multiple pieces were taken and divided in the same manner as in Example 1, and the break defect rate and the three-point bending strength were similarly determined. The results were as shown in Table 1.

表１から分かる通り、実施例１〜４のセラミックス基板は、ブレイク不良率が低減したものである。これに対し、比較例１のセラミックス基板はブレイク不良率が高いことが確認された。

As can be seen from Table 1, the ceramic substrates of Examples 1 to 4 have a reduced break defect rate. On the other hand, it was confirmed that the ceramic substrate of Comparative Example 1 has a high break defect rate.

<Example 5>
A ceramic sintered body shown in Table 2 was prepared by sintering aluminum oxide powder as a main component and adding 3% by mass of yttrium oxide as a sintering aid as a ceramic raw material. As shown in Table 2, break grooves were formed on both surfaces of the ceramic sintered body.
In the same manner as in Example 1, multiple pieces were taken and divided, and the break defect rate and handling properties were determined. Here, the handling property was evaluated by determining the ratio (%) of samples in which cracking or chipping occurred in the degreasing or sintering process (the total number of samples was 100).
The results were as shown in Table 2.

表２から分かる通り、切欠き部のセラミックス基板の断面方向への長さＢ１、Ｂ２が大きくなる程、ブレイク不良率が低下することが分かる。しかし、Ｂ１、Ｂ２が大きくなる程、脱脂および焼結時の割れ率が高くなり、ハンドリング性が低下することが判明した。これはＢ１、Ｂ２を大きくすることにより成形体または焼結体のブレイク溝形成部の強度が低下したためであり、焼結時のセラミックス成形体の収縮や、脱脂または焼結工程でのセラミックス成形体の搬送中にセラミックス成形体が破損したものと考えられる。

As can be seen from Table 2, it can be seen that the break defect rate decreases as the lengths B1 and B2 of the cutout portion in the cross-sectional direction of the ceramic substrate increase. However, it has been found that as B1 and B2 increase, the cracking rate during degreasing and sintering increases, and the handling property decreases. This is because the strength of the break groove forming part of the molded body or sintered body is reduced by increasing B1 and B2, and the ceramic molded body is shrunk during sintering or degreased or sintered. It is considered that the ceramic molded body was damaged during the conveyance of the film.

<Example 6 and Comparative Example 2>
On one side of the ceramic substrates of Examples 1 to 4 and Comparative Example 1 (that is, on the side of the notch portions (A2, B2)), a metal circuit board (this metal circuit board is 2 mm wide × 10 mm long × 0 mm thick). The ceramic circuit board shown in Table 3 was manufactured by providing two 3 mm copper plates). A copper plate having a width of 8 mm, a length of 10 mm, and a thickness of 0.3 mm was bonded to the surface of the ceramic substrate on which the metal circuit board was not provided (that is, on the side of the notches B (A1, B1)) to prevent warping.

  The TCT characteristics of each ceramic circuit board were evaluated. TCT characteristics were evaluated by confirming the presence or absence of cracks in the ceramic substrate after 100 cycles, with −40 ° C. × 30 minutes → 25 ° C. × 10 minutes → 125 ° C. × 10 minutes → 25 ° C. × 10 minutes as one cycle. . The results were as shown in Table 3.

  Further, as Comparative Example 6-2, a molded body having the same size as Comparative Example 1 and a substrate manufactured without providing a break groove was prepared.

  In the joining method of metal plates, the active metal method is a method of joining by performing heat treatment at 800 to 880 ° C. using a 70 wt% Ag-27 wt% Cu-3 wt% Ti brazing material. The direct bonding method is a method in which a copper plate is brought into contact with a ceramic substrate and subjected to heat treatment at 1065 to 1083 ° C. to form a eutectic of copper and oxygen. Note that when the direct bonding method is performed on the aluminum nitride substrate, the aluminum oxide film having a thickness of 1 μm is formed on the surface.

表３から分かる通り、実施例６−１−１〜実施例６−４−１のセラミックス基板は、ＴＣＴ試験において多数個取りを行わない方法で製造された比較例６−２と同等の優れた特性を示すことが確認された。
また、比較例６−１はＴＣＴ試験後にクラックが発生していることが確認された。これは分割した際にブレイク溝を設けていない側の面の端部にバリや微小クラックが発生してしまい部分的に強度が低下したためであると考えられる。

As can be seen from Table 3, the ceramic substrates of Example 6-1-1 to Example 6-4-1 were as excellent as Comparative Example 6-2, which was manufactured by a method that did not take multiple pieces in the TCT test. It was confirmed to show characteristics.
Further, it was confirmed that cracks occurred in Comparative Example 6-1 after the TCT test. This is considered to be due to the occurrence of burrs and microcracks at the end of the surface on the side where no break groove is provided when divided, resulting in a partial reduction in strength.

<Example 7>
Used as a ceramic raw material mainly composed of aluminum nitride and silicon nitride, as shown in Table 4, ceramic substrates with different substrate thicknesses were manufactured, and the break defect rate and handling properties due to differences in substrate thickness were evaluated. .
The results are as shown in Table 4.

表４から明らかなように、本発明によれば分割性が良好な厚さ０．６〜２．０ｍｍのセラミックス基板に有効である。基板厚さが０．６ｍｍ未満では両面にブレイク溝を設ける効果が小さい。一方、基板厚さが２．０ｍｍを超えるとセラミックス基板のブレイク不良率が増加する。これは、セラミックス基板を構成するセラミックス焼結体の強度が高いために厚い焼結体を分割するのが困難なためである。言い換えれば、本発明の両面にブレイク溝を設けるセラミックス基板は基板厚さが０．６〜２．０ｍｍのものに特に効果的であると言える。

As is apparent from Table 4, the present invention is effective for a ceramic substrate having a thickness of 0.6 to 2.0 mm with good partitionability. When the substrate thickness is less than 0.6 mm, the effect of providing break grooves on both sides is small. On the other hand, when the substrate thickness exceeds 2.0 mm, the break defect rate of the ceramic substrate increases. This is because it is difficult to divide the thick sintered body because the strength of the ceramic sintered body constituting the ceramic substrate is high. In other words, it can be said that the ceramic substrate provided with the break grooves on both sides of the present invention is particularly effective when the substrate thickness is 0.6 to 2.0 mm.

[Effect of the invention]
According to the present invention, it is possible to obtain a ceramic substrate that has good handling properties, can suppress the occurrence of burrs and the like, and has excellent splitting properties.

1 Ceramic substrate 2 Ceramic substrate side b Cut section B Cut section

Claims (2)

To produce a ceramic sintered body by sintering a sheet-shaped ceramic molded body, then this ceramic sintered body to form a break groove, obtained by dividing the then the ceramic sintered body along the break groove A ceramic circuit board manufacturing method comprising providing a metal plate on a ceramic substrate , wherein the ceramic substrate has a thickness of 0.6 to 2.0 mm, and the break groove is formed on the upper surface of the ceramic sintered body and The total of the width of the break groove formed on the bottom surface is 0.1 to 0.5 mm, the length of the break groove formed on the top surface in the cross-sectional direction and the length of the break groove formed on the bottom surface is ceramics. der 1/4 to 1/2 of the thickness of the substrate is, the cross section of the ceramic substrate of the notch portion formed in the upper portion of the side surface of the ceramic substrate Length of the notch formed at the lower end and the length of the notch formed at the lower end in the cross-sectional direction of the ceramic substrate, the length of the notch formed at the upper end in the cross-sectional direction of the ceramic substrate and providing a metal circuit plate towards the shorter notch when compared with the length of the cross-sectional direction of the ceramic substrate of the notch formed at the lower end to the method of manufacturing a ceramic circuit board . 2. The method of manufacturing a ceramic circuit board according to claim 1, wherein the break groove has a V-shaped or U-shaped shape.

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