JP5147620B2 - Ceramic substrate - Google Patents

Description

  The present invention relates to a novel ceramic substrate used for a wiring board or the like. Specifically, the present invention provides a ceramic substrate that has a break line, suppresses the generation of cracks due to the break line during handling before division, and is easily divided by the break line during division.

  Ceramic substrates typified by alumina and aluminum nitride are used in various fields such as electronic circuit members for automobiles and power modules, and submounts for heat sinks.

  Many of such ceramic substrates are obtained by punching at the green sheet stage and processing into a predetermined shape, followed by degreasing and firing. In such a manufacturing method, when a large number of chips are obtained from one ceramic substrate, so-called multi-chip taking is performed, a V-shaped groove called a break line is put in a green sheet, and after firing, along the break line. The method of dividing is generally adopted.

  As a method of manufacturing a ceramic substrate having the break line, a method of grooving by irradiating a ceramic green body sheet with a laser (Patent Document 1) or a method of grooving by a diamond cutter after firing a ceramic molded body (Patent Document) 2) A method of forming a groove while forming a green sheet by setting a blade with a sharp tip on the lip of an extrusion die (Patent Document 3). A press working for forming a groove (Patent Document 4) is known.

  Among these methods, press working using a die having a break blade attached is generally employed from the viewpoint of cost and efficiency in manufacturing a ceramic substrate. That is, ceramics are generally hard and difficult to deform, and cutting after obtaining a sintered body tends to increase the cost. Therefore, it is desirable to form the green body in a shape that does not require cutting as much as possible, and it is industrially practiced to form the break line on the green body by pressing. .

  In the press work, a break blade having a sharp tip is commonly used so that a groove can be easily formed by pressing.

  However, the ceramic substrate having a break line obtained by the press work is likely to crack at the break line before the division due to handling in the subsequent process or impact of conveyance, and the yield is reduced. There was a problem of letting.

Japanese Patent Laid-Open No. 9-1530 JP-A-9-232101 Japanese Patent Laid-Open No. 7-290428 JP-A-7-323414

  Accordingly, an object of the present invention is to suppress the generation of cracks due to the break line during handling before the division of the ceramic substrate in which the break line is formed by pressing at the green sheet stage, and at the time of the division. An object of the present invention is to provide a ceramic substrate that can be easily divided by the break line.

  The present inventors have repeatedly studied to achieve the above object. As a result, in a conventional press work, when a break blade having a sharp edge that is commonly used is used, the cross-sectional shape of the bottom of the groove formed by the break blade becomes an acute angle, and the bottom of the break line starts after firing. As a result, cracks are generated in the thickness direction of the sheet, and the fact that the depth of the break line is substantially deeper than the target depth makes the portion extremely susceptible to cracking.

  Based on the above knowledge, the bottom cross-sectional shape of the groove formed by the break blade is made into a non-acute angle shape with a specific width, and the depth of the groove is set to a specific depth, thereby generating at the bottom of the groove. It has been found that cracks can be effectively prevented and that the splitting property can be maintained well when the ceramic substrate is split, and the present invention has been completed.

That is, the present invention is a ceramic having a break line formed by firing a ceramic green sheet, and formed by pressing the ceramic green sheet and having a V-shaped groove having a cross section of 20 ° to 40 °. In the substrate, the depth of the groove forming the break line is 3 to 25% with respect to the thickness of the substrate, the width (W1) of the opening cross section of the groove is 20 to 100 μm, and the bottom cross section of the groove The ratio of the width (W2) of the bottom section of the groove formed into a non -acute angle shape with a width of 5 μm or more and the non-acute angle shape to the width (W1) of the opening section of the groove (W2 / W1) ) Of 0.25 to 0.5 .

  According to the present invention, stress can be prevented from concentrating at the bottom of the groove forming the break line without impairing the division of the ceramic substrate having the break line formed by pressing the ceramic green sheet. Generation of cracks can be effectively prevented. As a result, it is possible to dramatically improve the yield in industrial production of the ceramic substrate.

  As the ceramic constituting the ceramic substrate of the present invention, known ceramics are used without any particular limitation. Examples thereof include known ceramics such as metal or metalloid oxides, nitrides, carbides, etc., and alumina, aluminum nitride, silicon nitride, etc. are common.

  The ceramic substrate of the present invention is intended for a ceramic substrate on which a break line is formed by pressing.

  In addition, press work is represented by the said patent document 4, and means the method of forming a groove | channel on a green sheet with the metal mold | die which attached the break blade so that it may mention later.

  As will be described later, in the press working, a break blade attached to a mold is pushed into the green sheet, whereby a V-shaped groove is formed in the green sheet by the shape of the break blade. Here, the angle (θ) of the cross-section of the V-shaped groove formed by the break blade needs to be a V-shape that forms an angle of 20 ° to 40 ° in the obtained ceramic substrate. It is preferable that it is (degree)-35 degrees. If the angle is smaller than 20 °, even if the shape of the bottom portion described later is a non-acute angle, cracks are likely to occur at the bottom portion of the break line, and a sufficient effect cannot be obtained. On the other hand, when the angle is larger than 40 °, if the break line is formed to the target depth, the width of the break line is widened to deteriorate the appearance, and the splitting property of the ceramic substrate tends to be lowered.

  The ceramic substrate of the present invention is characterized in that, in the ceramic substrate having a break line made of the V-shaped groove, the depth of the groove forming the break line is 3 to 25%, preferably 8%. And the width (W2) of the bottom cross section of the groove is 5 μm or more, preferably 10 to 20 μm, and is formed into a non-acute angle shape.

  When the depth of the groove forming the break line, that is, the vertical depth from the surface of the ceramic substrate to the bottom of the break line is less than 3% with respect to the thickness of the substrate, the workability when dividing the ceramic substrate is improved. Lots that are reduced and do not break along the break line also occur, and the object of the present invention cannot be achieved. Further, when the depth of the groove is deeper than 25% with respect to the thickness of the substrate, the yield due to cracks during handling before division is reduced.

  Further, when the width of the groove having a non-acute angle at the bottom cross-sectional shape is narrower than 5 μm, cracks are likely to occur in such places, and the yield due to cracks during handling before division is reduced, thereby achieving the object of the present invention. Can not do it.

  In the present invention, the mechanism that exerts the effect of suppressing the occurrence of cracks by making the width (W2) that makes the bottom cross-sectional shape of the groove constituting the break line a non-acute angle is 5 μm or more is not clear. In firing the sheet, it is presumed that the stress applied to the bottom of the break line of the ceramic substrate can be dispersed and cracks are less likely to occur.

  The thickness of the ceramic substrate of the present invention is not particularly limited, but is generally 0.3 to 2 mm, particularly 0.5 to 1.2 mm.

  The structure of the ceramic substrate of the present invention will be described more specifically with reference to the accompanying drawings. FIG. 1 is a schematic view showing an embodiment of a ceramic substrate 1 having a break line 2. FIG. 1 shows an embodiment in which the break line 2 is formed only in one direction on the surface of the ceramic substrate. However, in the present invention, the break line may be formed in a direction orthogonal to each other. In the present invention, the number and interval of break lines can be determined as appropriate according to the size of the target ceramic substrate.

  2 to 4 are cross-sectional views showing typical cross-sectional shapes of grooves constituting break lines formed in the ceramic substrate of the present invention. That is, FIG. 2 is a mode in which the non-acute angle shape is obtuse, FIG. 3 is a mode in which the non-acute angle shape is curved, and FIG. 4 is a mode in which the non-acute angle shape is linear. . In any embodiment, as described above, the depth (D) of the groove forming the break line needs to be 3 to 25% with respect to the thickness of the substrate.

  Further, the width (W1) of the opening section of the groove constituting the break line is 20 to 100 μm, preferably 30 to 70 μm, and has a non-acute angle with respect to the width (W1) of the opening section of the groove. The ratio of the width (W2) of the bottom cross section of the groove formed (W2 / W1) is 0.25 to 0.5, preferably 0.3 to 0.4. It is preferable for further exhibiting the effect of suppressing the occurrence of cracks.

  The method for producing the ceramic substrate of the present invention is not particularly limited, but a typical production method is exemplified by a method comprising the steps shown in FIG. That is, in FIG. 5, (A) a slurry-like composition containing ceramic powder is formed into a sheet by a doctor blade method to obtain a green sheet 6, and (B) the green sheet 6 is shrunk by firing. In consideration of the above, etc., a step of forming the grooves constituting the break line by press working using the mold 3 so as to satisfy the conditions of the present invention after firing, (C) a green sheet on which the break line is formed 6 includes a step of accommodating 6 in a degreasing jig 7 and degreasing, and (D) a step of accommodating the degreased body obtained in the above step in a firing jig and firing to obtain a ceramic substrate.

  In the above method, the known composition of the ceramic green sheet is not particularly limited for each ceramic. Among these, when manufacturing a ceramic substrate of aluminum nitride, the following compositions can be cited as preferred compositions for applying press working. For example, 2 to 6 parts by weight of yttria as a sintering aid, 4 to 30 parts by weight of a binder, 20 to 200 parts by weight of an organic solvent, and a surfactant as another component with respect to 100 parts by weight of aluminum nitride powder. Examples include a composition containing 0.01 to 10 parts by weight and 0.1 to 20 parts by weight of a plasticizer.

  Moreover, the method of forming the groove | channel which comprises a break line by press work has the break blade 4 and the punching blade 5, for example, mounting the green sheet 1 in the lower mold | type of the metal mold | die 3, as shown in FIG. The upper mold of the mold 3 is pushed down, a break line is formed on the sheet by the break blade, and the sheet is cut by the punching blade 5.

  The press working can be performed using a known apparatus. For example, there is a mechanical press machine HAPJ-12 (trade name) manufactured by Noguchi Press Co., Ltd. or a servo press machine SSP-1000 (trade name) manufactured by Nippon Automatic Machine Co., Ltd.

  Moreover, the method of making the width | variety (W2) of the bottom part cross section of this groove | channel into a non-acute-angle shape by the said press work uses the shape where the shape of the front-end | tip of the break blade to use comprises this shape. Is common.

  In this method, degreasing and firing of the ceramic green sheet on which the break line is formed can be performed under known conditions.

  For example, when producing a ceramic substrate of aluminum nitride, degreasing is performed under an oxidizing gas such as oxygen or air, a reducing gas such as hydrogen, an inert gas such as nitrogen or argon, carbon dioxide, or a mixed gas atmosphere thereof. Alternatively, it is generally carried out at a temperature of 300 to 1200 ° C., preferably 400 to 600 ° C., for 0.5 to 10 hours, preferably 2 to 8 hours in a humidified gas atmosphere in which these gases and water vapor are mixed. The degreasing temperature and time can be appropriately selected depending on the binder and the degreasing atmosphere. From the viewpoint of improving the thermal conductivity of the obtained aluminum nitride sintered body, these conditions are appropriately adjusted to adjust the degreasing oxygen concentration. Is preferably controlled to be in the range of 3.0% by weight or less, and more preferably in the range of 0.9 to 2.5% by weight.

  On the other hand, as shown in FIG. 5, the degreased body is fired after the degreased body is accommodated in a firing jig and then in a non-oxidizing gas atmosphere, vacuum, or reduced pressure in a firing furnace such as a tunnel furnace. Done in As the non-oxidizing gas, for example, a reducing gas such as hydrogen, an inert gas such as argon, helium or nitrogen, or a mixed gas thereof is used. The firing temperature is usually in the range of 1650 ° C. to 1900 ° C., preferably 1750 ° C. to 1800 ° C., more preferably 1760 ° C. to 1790 ° C.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1
Aluminum nitride powder, yttrium oxide, organic solvent and binder resin were added and mixed in a nylon pot filled with alumina balls with an internal volume of 10 L, and then the solvent was removed to adjust the viscosity to 20000 cP. A slurry was obtained. Thereafter, sheet forming was performed by a doctor blade method to obtain an aluminum nitride green sheet having a width of 200 mm and a thickness of 0.75 mm.

  As shown in FIG. 7, the green sheet is formed on the upper die of the mold so that a piece having a molded body size of 90 × 104 mm to 42 × 48 mm can be divided into four pieces. The angle of the step) is 30 °, the angle of the blade tip (second step) is 90 °, the width of the blade tip (equivalent to W2) is 6 μm, A die to which six break blades having a height of 150 μm were attached was attached to a press machine (HAPJ-12 manufactured by Noguchi Press Co., Ltd .; trade name), and an aluminum nitride green sheet was punched and formed.

  The aluminum nitride green sheet thus punched and formed was degreased in dry air at a temperature of 580 ° C. for 4 hours to obtain an aluminum nitride degreased body having an oxygen concentration of 2.2% by weight. Further, this degreased body was filled in a boron nitride (BN) firing container and fired at 1740 ° C. for 5 hours to obtain an aluminum nitride substrate made of an aluminum nitride sintered body.

  When the width W1 of the opening of the break line formed in the obtained aluminum nitride substrate and the width W2 of the bottom of the groove were confirmed by SEM, they were 20 μm and 5 μm, respectively. The depth of the groove was 90 μm. In addition, the board | substrate cracked from the break line during the manufacturing process was 0.2% or less of the whole.

  Furthermore, the oil-based magic was applied to 10 break lines (1 to 10 shown in FIG. 7) of the obtained aluminum nitride sintered body and divided along the break lines. Using the bottom of the groove formed by the break blade as a starting point, the ink penetration depth (crack depth) was measured with a major microscope.

  Further, five aluminum nitride substrates were divided in the same manner, and the average value of the crack depths for each part was determined. The results are shown in Table 1. Further, the outer periphery of the divided pieces was inspected with a stereoscopic microscope (SZ-40 manufactured by Olympus Corporation) to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2. .

  As shown in Table 1, no cracks were confirmed, and as shown in Table 2, no burrs or burrs were confirmed.

Example 2
In Example 1, Example 1 was used except that a die having the shape shown in FIG. 3, the radius of curvature of the tip of the blade being 8 μm, and six break blades having a blade height of 150 μm attached thereto was used. In the same manner, an aluminum nitride sintered body was obtained. When the width W1 of the opening of the break line formed in the aluminum nitride substrate and the width W2 of the bottom of the groove were confirmed by SEM, they were 50 μm and 14 μm, respectively. The groove depth was 86 μm. In addition, the board | substrate cracked from the break line during the manufacturing process was 0.3% or less of the whole.

  Furthermore, the average value of the crack depth from the bottom of the break groove was determined in the same manner as in Example 1, and the results are shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2.

  As shown in Table 1, no cracks were confirmed, and as shown in Table 2, no burrs or burrs were confirmed.

Example 3
In Example 1, except that a die having a shape shown in FIG. 4 and having a blade tip width (equivalent to W2) of 10 μm and six break blades with a blade height of 150 μm attached thereto was used. In the same manner as in Example 1, an aluminum nitride sintered body was obtained. When the width W1 of the opening of the break line formed in the aluminum nitride substrate and the width W2 of the bottom of the groove were confirmed by SEM, they were 36 μm and 9 μm, respectively. The depth of the groove was 78 μm. In addition, the board | substrate cracked from the break line during the manufacturing process was 0.1% or less of the whole.

  Furthermore, the average value of the crack depth of the crack from the bottom part of a break groove | channel was calculated | required by the same method as Example 1, and the result was shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2.

  As shown in Table 1, no cracks were confirmed, and as shown in Table 2, no burrs or burrs were confirmed.

Example 4
In Example 1, the base of the blade (first stage) has a 30 ° angle in the shape shown in FIG. 2, and the angle formed by the blade tip (second stage) is 120 °. The aluminum nitride sintered body was manufactured in the same manner as in Example 1 except that a die having a breaker having a width of 19 μm (equivalent to W2) and a blade height of 150 μm and six break blades attached thereto was used. Obtained. When the width W1 of the opening of the break line formed on the substrate and the width W2 of the bottom of the groove were confirmed by SEM, they were 47 μm and 17 μm, respectively. The depth of the groove was 75 μm. In addition, the board | substrate cracked from the break line during the manufacturing process was 0.1% or less of the whole.

  Furthermore, the average value of the crack depth from the bottom of the break groove was determined in the same manner as in Example 1, and the results are shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2.

  As shown in Table 1, no cracks were confirmed, and as shown in Table 2, no burrs or burrs were confirmed.

Example 5
In Example 1, Example 1 was used except that a die having a shape shown in FIG. 3 and having a radius of curvature of the blade tip portion of 15 μm and six break blades having a blade height of 150 μm was attached. In the same manner, an aluminum nitride sintered body was obtained. When the width W1 of the opening of the break line formed in the aluminum nitride substrate and the width W2 of the bottom of the groove were confirmed by SEM, they were 56 μm and 27 μm, respectively. The depth of the groove was 78 μm. In addition, the board | substrate cracked from the break line during the manufacturing process was 0.2% or less of the whole. Furthermore, the average value of the crack depth from the bottom of the break groove was determined in the same manner as in Example 1, and the results are shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more.

  As shown in Table 1, no cracks were confirmed, and as shown in Table 2, no burrs or burrs were confirmed.

Example 6
In Example 1, except that a die having the shape shown in FIG. 4 and having a blade tip width (equivalent to W2) of 20 μm and six break blades having a blade height of 150 μm attached thereto was used. In the same manner as in Example 1, an aluminum nitride sintered body was obtained. When the width W1 of the opening of the break line formed on the aluminum nitride substrate and the width W2 of the bottom of the groove were confirmed by SEM, they were 51 μm and 18 μm, respectively. The depth of the groove was 56 μm.

  In addition, the board | substrate cracked from the break line during the manufacturing process was 0.3% or less of the whole. Furthermore, the average value of the crack depth from the bottom of the break groove was determined in the same manner as in Example 1, and the results are shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2.

  As shown in Table 1, no cracks were confirmed, and as shown in Table 2, no burrs or burrs were confirmed.

Comparative Example 1
In Example 1, the base of the blade (first stage) has a 30 ° angle in the shape shown in FIG. 2, and the angle formed by the blade tip (second stage) is 90 °. The aluminum nitride sintered body was prepared in the same manner as in Example 1 except that a die having 6 break blades having a width (equivalent to W2) of 3 μm and a blade height of 150 μm was used. Obtained. When the width W1 of the opening of the break line formed on the aluminum nitride substrate and the width W2 of the bottom of the groove were confirmed by SEM, they were 50 μm and 2.5 μm, respectively. The groove depth was 92 μm.

  In addition, the board | substrate which broke from the break line during the manufacturing process was 18% of the whole. Furthermore, the average value of the crack depth from the bottom of the break groove was determined in the same manner as in Example 1, and the results are shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2. As shown in Table 1, cracks occurred in most places. Further, as shown in Table 2, no burrs or burrs were observed.

Comparative Example 2
In Example 1, Example 1 was used except that a die having a shape shown in FIG. 3, a radius of curvature of the blade tip portion of 2 μm, and six break blades having a blade height of 150 μm was attached. In the same manner, an aluminum nitride sintered body was obtained. When the width W1 of the opening of the break line and the width W2 of the bottom of the groove formed on the aluminum nitride substrate were confirmed by SEM, they were 38 μm and 3 μm, respectively. The depth of the groove was 85 μm.

  In addition, the board | substrate which broke from the break line during the manufacturing process was 13% of the whole. Furthermore, the average value of the crack depth from the bottom of the break groove was determined in the same manner as in Example 1, and the results are shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2.

  As shown in Table 1, cracks occurred in most places. Further, as shown in Table 2, no burrs or burrs were observed.

Comparative Example 3
In Example 1, except that a die having the shape shown in FIG. 4 and having a blade tip width (equivalent to W2) of 5 μm and six break blades with a blade height of 150 μm attached thereto was used. In the same manner as in Example 1, an aluminum nitride sintered body was obtained. When the width W1 of the opening of the break line formed on the aluminum nitride substrate and the width W2 of the bottom of the groove were confirmed by SEM, they were 48 μm and 4 μm, respectively. The groove depth was 83 μm.

  In addition, the board | substrate which broke from the break line during the manufacturing process was 16% of the whole. Furthermore, the average value of the crack depth from the bottom of the break groove was determined in the same manner as in Example 1, and the results are shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2.

  As shown in Table 1, cracks occurred in more than half of the places. Moreover, as shown in Table 2, burrs or chips were partially confirmed.

Comparative Example 4
In Example 1, the base of the blade (first stage) has an angle of 30 ° in the shape shown in FIG. 2, and the angle formed by the tip of the blade (second stage) is 50 °. An aluminum nitride sintered body was obtained in the same manner as in Example 1 except that a die attached with six break blades having a tip width of 6 μm and a blade height of 150 μm was used. When the width W1 of the opening of the break line formed in the aluminum nitride substrate and the width W2 of the bottom of the groove were confirmed by SEM, they were 41 μm and 5 μm, respectively. The groove depth was 89 μm.

  Note that 21% of the substrates were broken from the break line during the manufacturing process. Furthermore, the average value of the crack depth from the bottom of the break groove was determined in the same manner as in Example 1, and the results are shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2.

  As shown in Table 1, cracks occurred at all locations. Further, as shown in Table 2, no burrs or burrs were observed.

Comparative Example 5
In Example 1, the embodiment shown in FIG. 3 was used except that a die having a cutting radius of 1.5 μm and a blade height of 150 μm and six break blades attached thereto was used. In the same manner as in Example 1, an aluminum nitride sintered body was obtained. When the width W1 of the opening of the break line and the width W2 of the bottom of the groove formed on the aluminum nitride substrate were confirmed by SEM, they were 50 μm and 2 μm, respectively. Further, the depth of the groove was 95 μm.

  In addition, the board | substrate which broke from the break line during the manufacturing process was 15% of the whole. Furthermore, the average value of the crack depth from the bottom of the break groove was determined in the same manner as in Example 1, and the results are shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2.

  As shown in Table 1, cracks occurred in most places. Further, as shown in Table 2, no burrs or burrs were observed.

Comparative Example 6
In Example 1, except that a die having the shape shown in FIG. 4 and having a blade tip width (equivalent to W2) of 25 μm and six break blades having a blade height of 150 μm attached thereto was used. In the same manner as in Example 1, an aluminum nitride sintered body was obtained. When the width W1 of the opening of the break line formed on the substrate and the width W2 of the bottom of the groove were confirmed by SEM, they were 45 μm and 23 μm, respectively. Further, the depth of the groove was 37 μm.

  In addition, the board | substrate which broke from the break line during the manufacturing process was 0.1% of the whole. Furthermore, the substrate was divided along the break line by the same method as in Example 1, but was broken at a portion other than the break line. The average value of the crack depth from the bottom of the break groove in the divided part was determined, and the results are shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2.

  As shown in Table 1, no cracks were observed, but almost half of the parts did not break along the break line. These unbreakable portions are indicated by “x” in Table 1. Moreover, as shown in Table 2, burrs or chips were partially confirmed.

Comparative Example 7
In Example 1, a die having a V-shape with a radius of curvature of 1.1 μm at the tip, an angle formed by the tip of the blade of 30 °, and six break blades with a blade height of 150 μm attached An aluminum nitride sintered body was obtained in the same manner as in Example 1 except that was used. When the width W1 of the opening of the break line and the width W2 of the bottom of the groove formed on the aluminum nitride substrate were confirmed by SEM, they were 50 μm and 2 μm, respectively. The groove depth was 93 μm.

  In addition, the board | substrate which broke from the break line during the manufacturing process was 25% of the whole. Furthermore, the average value of the crack depth from the bottom of the break groove was determined in the same manner as in Example 1, and the results are shown in Table 1. In addition, the appearance of the outer peripheral portion of each piece divided by the same method as in Example 1 was examined to determine the presence or absence of burrs and the number of chips of 0.5 mm or more. The results are shown in Table 2. As shown in Table 1, cracks occurred in most places. Further, as shown in Table 2, no burrs or burrs were observed.

Schematic diagram of ceramic substrate with break line Sectional drawing which shows the typical cross-sectional shape of the groove | channel which comprises the break line formed in the ceramic substrate of this invention Sectional drawing which shows the other typical cross-sectional shape of the groove | channel which comprises the break line formed in the ceramic substrate of this invention Sectional drawing which shows the other typical cross-sectional shape of the groove | channel which comprises the break line formed in the ceramic substrate of this invention Diagram showing an example of the manufacturing process of a ceramic substrate The schematic diagram which shows the formation method of the break line formed in the ceramic substrate of this invention Schematic which shows the measurement position of the crack depth of the break line of the aluminum nitride sintered compact in an Example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 Break line 3 Die for press molding 4 Break blade 5 Punching blade 6 Green sheet 7 Degreasing jig 8 Firing jig

Claims (2)

A ceramic substrate obtained by firing a ceramic green sheet and having a break line formed by pressing the ceramic green sheet and having a V-shaped groove having a cross section of 20 ° to 40 °. The depth of the groove forming the groove is 3 to 25% of the thickness of the substrate, the width (W1) of the opening cross section of the groove is 20 to 100 μm, and the bottom cross-sectional shape of the groove is 5 μm or more wide And the ratio (W2 / W1) of the width (W2) of the bottom section of the groove formed into a non-acute angle shape and the width (W1) of the opening section of the groove is 0.25 to 0.25. A ceramic substrate characterized by being 0.5 .   The ceramic substrate according to claim 1, wherein the non-acute shape is obtuse, curved, or linear.

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