Ceramic composite substrate and method for manufacturing the same

Abstract

To improve coating property of a joint material to a metal body.SOLUTION: A ceramic composite substrate comprises: a ceramic plate; a plurality of first metal bodies formed so as to be arrayed in a two-dimensional manner of M rows and N columns; a plurality of second metal bodies; one or more first scribe lines; and one or more second scribe lines. In at least a portion of a predetermined first evaluation line, the ceramic plate protrudes in a direction from a second principal surface to a first principal surface. When an amount obtained by dividing a difference between a maximum value and a minimum value of the second principal surface in a first height direction orthogonal to a first evaluation line with a length of the first evaluation line is defined as a first warpage amount, the first warpage amount ranges from 0.05×10-2 to 0.2×10-2. The first evaluation line is set between the first metal body of a (N / 2)th column and a first metal body of a (N / 2+1)th column or set between a first metal body of a (N / 2-0.5)th column and a first metal body of a (N / 2+0.5)th column.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a ceramic composite substrate and a method for manufacturing the ceramic composite substrate.

Background Art

[0002] Patent Document 1 discloses a ceramic circuit board in which a plurality of metal circuit boards are provided on a ceramics substrate, and a single metal plate made of the same metal as the metal circuit board is provided on the opposite surface side of the ceramics substrate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a ceramic composite substrate useful for improving the coatability of a bonding material to a metal body, and a method for manufacturing the ceramic composite substrate.

Means for Solving the Problems

[0005] The ceramic composite substrate according to one aspect of the present disclosure includes a ceramic plate, a plurality of first metal bodies, a plurality of second metal bodies, one or more first scribe lines, and one or more second scribe lines. The ceramic plate has a first main surface and a second main surface. The plurality of first metal bodies are formed to be two-dimensionally arranged in M rows and N columns (M and N are integers of 2 or more) on the first main surface. The plurality of second metal bodies are formed to be two-dimensionally arranged at positions corresponding to the plurality of first metal bodies on the second main surface. One or more first scribe lines are located between adjacent first metal bodies among the N first metal bodies arranged in the longitudinal direction of the ceramic plate, and are formed on the first main surface so as to extend along the short-side direction of the ceramic plate. One or more second scribe lines are located between adjacent first metal bodies among the M first metal bodies arranged in the short-side direction, and are formed on the first main surface so as to extend along the longitudinal direction. At least a part of a predetermined first evaluation line set so as to connect both ends of the second main surface in the short-side direction with a straight line, the ceramic plate protrudes in a direction from the second main surface toward the first main surface. When an amount obtained by dividing the difference between the maximum value and the minimum value of the second main surface in the first height direction orthogonal to the first evaluation line by the length of the first evaluation line is defined as the first warpage amount, the first warpage amount is 0.05×10 -2 ~0.2×10 -2 is satisfied. The first evaluation line is set between the first metal body in the (N / 2)th column and the first metal body in the (N / 2 + 1)th column when N is an even number, and is set between the first metal body in the (N / 2 - 0.5)th column and the first metal body in the (N / 2 + 0.5)th column when N is an odd number.

[0006] In this ceramic composite substrate, at least a part of the first evaluation line extending along the short-side direction, the ceramic plate protrudes upward from the second main surface toward the first main surface, and the first warpage amount is 0.05×10 -2 ~0.2×10 -2In this case, when the ceramic composite substrate is singulated, the warpage amount when the singulated split substrate warps upward and the warpage amount when the split substrate warps downward are reduced. By reducing the warpage amount, it is less likely that there will be uncoated areas when applying the bonding material to the metal body. Therefore, this ceramic composite substrate is useful for improving the coatability of the bonding material to the metal body.

[0007] When the difference between the maximum value and the minimum value of the second main surface in the second height direction orthogonal to a predetermined second evaluation line set so as to connect both ends of the second main surface in the longitudinal direction with a straight line is divided by the length of the second evaluation line, the resulting amount is defined as the second warpage amount, the second warpage amount may be smaller than 0.1×10 -2 Even smaller. The second evaluation line may be set between the first metal body in the (M / 2)th row and the first metal body in the (M / 2 + 1)th row when M is an even number, or may be set between the first metal body in the (M / 2 - 0.5)th row and the first metal body in the (M / 2 + 0.5)th row when M is an odd number. In this case, since the warpage amount of the ceramic plate 20 is also small in the longitudinal direction, the warpage amount in the singulated state can be further suppressed. Therefore, when applying the bonding material to the metal body, it is even less likely that there will be uncoated areas. Therefore, it is even more useful for improving the coatability of the bonding material to the metal body.

[0008] The ratio of the volume of the first metal body located at m rows and n columns to the volume of the second metal body located at m rows and n columns may be 0.95 to 1.05. m may be an integer from 1 to M, and n may be an integer from 1 to N. In this case, there is a tendency for the warpage amount at the time of singulation to be small. Therefore, it is even more useful for improving the coatability of the bonding material to the metal body.

[0009] The manufacturing method according to one aspect of the present disclosure includes a ceramic plate having a first main surface and a second main surface, a plurality of first metal bodies formed in a two-dimensional array in M rows and N columns (M and N are integers of 2 or more) on the first main surface, a plurality of second metal bodies formed in a two-dimensional array at positions corresponding to the plurality of first metal bodies on the second main surface, one or more first scribe lines formed on the first main surface so as to be located between adjacent first metal bodies among the N first metal bodies arranged in the longitudinal direction of the ceramic plate and extend along the short side direction of the ceramic plate, and one or more second scribe lines formed on the first main surface so as to be located between adjacent first metal bodies among the M first metal bodies arranged in the short side direction and extend along the longitudinal direction. This manufacturing method includes a step of evaluating whether the ceramic plate protrudes from the second main surface toward the first main surface at at least a part of a predetermined first evaluation line set to connect both ends of the second main surface in the short side direction with a straight line, and when an amount obtained by dividing the difference between the maximum value and the minimum value of the second main surface in the first height direction orthogonal to the first evaluation line by the length of the first evaluation line is defined as the first warpage amount, evaluating whether the first warpage amount is 0.05×10 -2 ~0.2×10 -2 or not. The first evaluation line is set between the first metal body in the (N / 2)th column and the first metal body in the (N / 2 + 1)th column when N is an even number, and is set between the first metal body in the (N / 2 - 0.5)th column and the first metal body in the (N / 2 + 0.5)th column when N is an odd number. In this manufacturing method, by evaluating the warpage at the evaluation line along the short side direction of the ceramic plate, it is possible to exclude a composite substrate in which the warpage amount can be large in the singulated state. Therefore, this manufacturing method is useful for improving the coatability of the bonding material to the metal body.

Effects of the Invention

[0010] According to the present disclosure, there are provided a ceramic composite substrate useful for improving the coatability of a bonding material to a metal body, and a manufacturing method of the ceramic composite substrate.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0012] Hereinafter, an embodiment will be described with reference to the drawings. However, the following embodiments are examples for explaining the present disclosure and are not intended to limit the present disclosure to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant descriptions may be omitted as appropriate. Also, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of each element are not limited to the ratios shown in the drawings.

[0013] [Ceramic composite substrate] FIGS. 1 and 2 schematically show an example of a ceramic composite substrate according to an embodiment. The ceramic composite substrate 10 is a substrate obtained by forming a predetermined metal body on a ceramic plate. The ceramic composite substrate 10 is formed so as to be dividable (into individual pieces) into a plurality of divided substrates. Each divided substrate (circuit board in a fragmented state) obtained by fragmenting the ceramic composite substrate 10 is used as a component such as a power module, for example.

[0014] (Ceramic plate) As shown in FIGS. 1 and 2, the ceramic composite substrate 10 has a ceramic plate 20. The ceramic plate 20 is, for example, a silicon nitride plate or an aluminum nitride plate. The ceramic plate 20 is formed in a flat plate shape. The ceramic plate 20 has a pair of main surfaces facing each other. Hereinafter, one of the pair of main surfaces will be referred to as "front surface 20A" and the other as "back surface 20B". FIG. 1 shows a perspective view when looking at the front surface 20A, and FIG. 2 shows a perspective view when looking at the back surface 20B on the side opposite to the front surface 20A.

[0015] The front surface 20A (the first main surface) and the back surface 20B (the second main surface) are each rectangular. In this case, the outer edges of the front surface 20A and the back surface 20B each include a pair of short sides and a pair of long sides. The sizes of the front surface 20A and the back surface 20B may be substantially the same as each other. In the present disclosure, the direction in which the short sides of the front surface 20A and the back surface 20B extend (the direction parallel to the short sides) is referred to as the "short-side direction D1", and the direction in which the long sides of the front surface 20A and the back surface 20B extend (the direction parallel to the long sides) is referred to as the "long-side direction D2". The length of the ceramic plate 20 in the short-side direction D1 is smaller than the length of the ceramic plate 20 in the long-side direction D2.

[0016] The thickness T of the ceramic plate 20 is set according to the use of the above-mentioned divided substrate or circuit board and the material of the ceramic plate 20. When the material forming the ceramic plate 20 contains silicon nitride, in one example, the thickness T is 0.15 mm to 0.50 mm. The thickness T may be 0.18 mm to 0.45 mm, or may be 0.20 mm to 0.40 mm. The thickness T is defined as the distance between the front surface 20A and the back surface 20B in the thickness direction of the ceramic plate 20. The thickness direction of the ceramic plate 20 may correspond to the direction orthogonal to the central portion of the front surface 20A.

[0017] The length of the ceramic plate 20 in the short-side direction D1 may be 100 mm to 200 mm, may be 110 mm to 190 mm, or may be 120 mm to 180 mm. The length of the ceramic plate 20 in the long-side direction D2 may be 140 mm to 250 mm, may be 150 mm to 240 mm, or may be 160 mm to 230 mm.

[0018] (Scribe line) The ceramic plate 20 has one or a plurality of scribe lines SL1 (first scribe lines) and one or a plurality of scribe lines SL2 (second scribe lines). In the example shown in FIG. 1, the ceramic plate 20 has a plurality of (three) scribe lines SL1 and a plurality of (two) scribe lines SL2. The plurality of scribe lines SL1 and the plurality of scribe lines SL2 are formed on the surface 20A. None of the scribe lines are formed on the back surface 20B.

[0019] Each of the plurality of scribe lines SL1 is formed to extend along the short side direction D1. The plurality of scribe lines SL1 are parallel to each other and are arranged at equal intervals along the long side direction D2. Each of the plurality of scribe lines SL2 is formed to extend along the long side direction D2. The plurality of scribe lines SL2 are parallel to each other and are arranged at equal intervals along the short side direction D1. The scribe line SL1 and the scribe line SL2 are orthogonal to each other.

[0020] The ceramic plate 20 is partitioned into a plurality of partition portions 22 (twelve partition portions 22 in the example shown in FIGS. 1 and 2) by the plurality of scribe lines SL1 and the plurality of scribe lines SL2. In other words, the ceramic plate 20 has a plurality of partition portions 22 defined by the plurality of scribe lines SL1 and the plurality of scribe lines SL2. The sizes (volumes) of the plurality of partition portions 22 may be substantially the same as each other.

[0021] FIG. 3 shows a cross-sectional view taken along line III-III shown in FIG. 1, and FIG. 4 shows a cross-sectional view taken along line IV-IV shown in FIG. 1. In the ceramic plate 20, the partition portion 22 located at the central portion without including the outer edge is a three-dimensional region defined by a partial region of the surface 20A surrounded by the scribe lines SL1 and SL2, a partial region of the back surface 20B on the opposite side corresponding to that region, and virtual lines VL1 and VL2 drawn parallel to the thickness direction of the ceramic plate 20 from the scribe lines SL1 and SL2. The partition portion 22 including the outer edge of the ceramic plate 20 is a three-dimensional region defined by a partial region of the surface 20A surrounded by the scribe lines SL1 and SL2 and the outer edge, a partial region of the back surface 20B corresponding to that region, the side surface of the ceramic plate 20, and the virtual lines VL1 and VL2.

[0022] As shown in FIG. 5, a plurality of partition portions 22 are formed to be two-dimensionally arranged in M rows and N columns. Each of M and N is an integer of 2 or more. The partition portion 22 located at the uppermost part in the vertical direction is the partition portion 22 in the first row, and the partition portion 22 located at the lowermost part in the vertical direction is the partition portion 22 in the Mth row. The partition portion 22 located at the leftmost in the horizontal direction is the partition portion 22 in the first column, and the partition portion 22 located at the rightmost in the horizontal direction is the partition portion 22 in the Nth column. The direction in which a total of M partition portions 22 are arranged corresponds to the short side direction D1, and the direction in which a total of N partition portions 22 are arranged corresponds to the long side direction D2.

[0023] FIGS. 6(a) and 6(b) show an enlarged view of the scribe line SL1 (SL2) provided on a part of the surface 20A. The scribe line SL1 is composed of a plurality of holes 24 arranged in a row along its extending direction (short side direction D1). Similarly, the scribe line SL2 is composed of a plurality of holes 24 arranged in a row along its extending direction (long side direction D2). The outer peripheral edge 24E of the hole 24 on the surface 20A may be a circle when viewed from a direction orthogonal to the surface 20A.

[0024] FIG. 6(a) illustrates a case where the pitch of a plurality of holes 24 arranged along the extending direction of the scribe line SL1 (hereinafter referred to as "array pitch p") substantially coincides with the diameter on the surface 20A of the hole 24 (hereinafter referred to as "aperture diameter r"). Different from the example shown in FIG. 6(a), the array pitch p may be smaller than the aperture diameter r of the hole 24. In this case, adjacent holes 24 overlap each other, and the outer peripheral edge 24E of one hole 24 becomes a pair of arcs instead of a complete circle. The array pitch p may be larger than the aperture diameter r of the hole 24. In this case, adjacent holes 24 are formed in a state of being separated from each other.

[0025] FIG. 6(b) shows a cross-section along the VIB-VIB line shown in FIG. 6(a). FIG. 6(b) is a cross-sectional view when the ceramic plate 20 is cut along a plane passing through the center of each hole 24 of the scribe line SL1 (SL2) and along the thickness direction of the ceramic plate 20. The hole 24 is formed in a mortar shape so as to taper from the surface 20A toward the inside of the ceramic plate 20. The magnitudes of the array pitch p, the aperture diameter r, and the depth d of the hole 24 may be set (designed) in consideration of various viewpoints including the mechanical strength of the ceramic plate 20, the ease of division along the scribe line, and the suppression of warpage of the ceramic composite substrate 10.

[0026] The lower limit value of the array pitch p is, for example, 30 μm, 35 μm, 40 μm, or 50 μm. The upper limit value of the array pitch p is, for example, 100 μm, 105 μm, 110 μm, or 120 μm. The array pitch p may be 30 μm to 120 μm, or may be 35 μm to 105 μm. The array pitch p is defined as the distance between the centers of adjacent holes 24. The lower limit value of the aperture diameter r is, for example, 50 μm, 60 μm, or 65 μm. The upper limit value of the aperture diameter r is, for example, 90 μm, 100 μm, 110 μm, or 120 μm. The aperture diameter r may be 50 μm to 120 μm, or may be 60 μm to 110 μm.

[0027] The depth d may be 1 / 6 to 1 / 3 times the thickness T of the ceramic plate 20. The lower limit value of the depth d is, for example, 50 μm, 60 μm, or 65 μm. The upper limit value of the depth d is, for example, 90 μm, 100 μm, 110 μm, or 120 μm. The depth d may be 50 μm to 120 μm, or may be 60 μm to 110 μm. The depth d is defined as the distance in the thickness direction of the ceramic plate 20 from the surface 20A to the bottom 24B (lowest point) of the hole 24. Between the scribe line SL1 and the scribe line SL2, the ranges of the array pitch p, the opening diameter r, and the depth d may coincide with each other, or at least one of the ranges of the array pitch p, the opening diameter r, and the depth d may be different from each other.

[0028] (Metal body) Returning to FIGS. 1 and 2, the ceramic composite substrate 10 has a plurality of front-side metal bodies 30A (a plurality of first metal bodies) and a plurality of back-side metal bodies 30B (a plurality of second metal bodies). The plurality of front-side metal bodies 30A are formed on the surface 20A, and the plurality of back-side metal bodies 30B are formed on the back surface 20B. Each of the plurality of front-side metal bodies 30A is joined to the surface 20A via, for example, a brazing material, and each of the plurality of back-side metal bodies 30B is joined to the back surface 20B via, for example, a brazing material.

[0029] The plurality of front-side metal bodies 30A are formed so as to be two-dimensionally arranged in M rows and N columns on the surface 20A. The plurality of front-side metal bodies 30A are arranged so as to respectively correspond to a plurality of partition portions 22 two-dimensionally arranged in M rows and N columns. That is, one front-side metal body 30A is formed in each partition portion 22. The front-side metal body 30A of the m-th row and n-th column is formed in the partition portion 22 located in the m-th row and n-th column. m is any integer from 1 to M, and n is any integer from 1 to N. A total of M front-side metal bodies 30A are arranged along the short-side direction D1, and a total of N front-side metal bodies 30A are arranged along the long-side direction D2.

[0030] The front-side metal body 30A may be formed in a plate shape. The front-side metal body 30A may be a copper plate. The thickness of the front-side metal body 30A may be smaller than the thickness T of the ceramic plate 20, may be approximately the same as the thickness T, or may be larger than the thickness T. The thickness of the front-side metal body 30A may be 0.4 mm to 2.5 mm, may be 0.45 mm to 2.3 mm, or may be 0.5 mm to 2.0 mm.

[0031] The length of the short-side direction D1 of the front-side metal body 30A and the length of the long-side direction D2 of the front-side metal body 30A may be substantially the same as each other or may be different from each other. The length of the short-side direction D1 of the front-side metal body 30A may be smaller than or larger than the length of the long-side direction D2 of the front-side metal body 30A. The length of the short-side direction D1 of the front-side metal body 30A may be 20 mm to 70 mm, may be 30 mm to 60 mm, or may be 35 mm to 50 mm. The length of the long-side direction D2 of the front-side metal body 30A may be 20 mm to 70 mm, may be 30 mm to 60 mm, or may be 35 mm to 50 mm.

[0032] When viewed from the surface 20A in the thickness direction of the ceramic plate 20, the outer edge of the front-side metal body 30A is located inside the outer edge of the corresponding partition portion 22. One front-side metal body 30A is surrounded by the outer edge of the partition portion 22. In other words, when viewed from the surface 20A in the thickness direction of the ceramic plate 20, the area of the front-side metal body 30A is smaller than the area of the partition portion 22. The shape of the outer edge of the front-side metal body 30A may be similar to the shape of the outer edge of the corresponding partition portion 22. The volumes (thickness and area) of the plurality of front-side metal bodies 30A may be substantially the same as each other.

[0033] The plurality of backside metal bodies 30B are formed so as to be two-dimensionally arranged at positions corresponding to the plurality of frontside metal bodies 30A on the back surface 20B. The plurality of backside metal bodies 30B are arranged so as to correspond to the plurality of partition portions 22 that are two-dimensionally arranged in M rows and N columns. That is, one backside metal body 30B is formed in each partition portion 22. In the present disclosure, the backside metal body 30B located on the opposite side of the m-row n-column frontside metal body 30A in the m-row n-column partition portion 22 is defined as the backside metal body 30B located in the m-row n-column. A total of M backside metal bodies 30B are arranged along the short-side direction D1, and a total of N backside metal bodies 30B are arranged along the long-side direction D2.

[0034] The backside metal body 30B may be formed in a plate shape. The material forming the backside metal body 30B is, for example, the same as the material (e.g., copper) forming the frontside metal body 30A. When looking at the back surface 20B from the thickness direction of the ceramic plate 20, the outer edge of the backside metal body 30B is located inside the outer edge of the corresponding partition portion 22. When looking at the back surface 20B from the thickness direction of the ceramic plate 20, the area of the backside metal body 30B is smaller than the area of the partition portion 22. The shape of the outer edge of the backside metal body 30B may be similar to the shape of the outer edge of the corresponding partition portion 22. The volumes (thickness and area) of the plurality of backside metal bodies 30B may be substantially the same as each other.

[0035] The volume of the frontside metal body 30A located in the m-row n-column may be substantially the same as the volume of the corresponding backside metal body 30B (the backside metal body 30B located in the m-row n-column). When these volumes are substantially the same, the ratio of the volume of the corresponding frontside metal body 30A to the volume of the backside metal body 30B located in the m-row n-column (hereinafter referred to as the "volume ratio of the metal bodies") is 0.95 to 1.05. The volume ratio of the metal bodies may be 0.97 to 1.03, or may be 0.99 to 1.01. The area of the frontside metal body 30A and the area of the backside metal body 30B may be substantially the same as each other, and the thickness of the frontside metal body 30A and the thickness of the backside metal body 30B may be substantially the same as each other. When viewed from the thickness direction of the ceramic plate 20, the outer edge of the frontside metal body 30A and the outer edge of the backside metal body 30B may be substantially the same as each other (may overlap).

[0036] The volume of the front-side metal body 30A may not substantially match the volume of the corresponding back-side metal body 30B and may be larger than the volume of the back-side metal body 30B. The volume ratio of the metal bodies may be greater than 1.05 and less than or equal to 1.2. The volume of the front-side metal body 30A may not substantially match the volume of the corresponding back-side metal body 30B and may be smaller than the volume of the back-side metal body 30B. The volume ratio of the metal bodies may be less than 0.95 and greater than or equal to 0.80. At least one of the area and the thickness may be different between the front-side metal body 30A and the back-side metal body 30B.

[0037] In the example shown in FIG. 1, the ceramic composite substrate 10 has (N - 1) scribe lines SL1 and (M - 1) scribe lines SL2. Each of the (N - 1) scribe lines SL1 is located between adjacent front-side metal bodies 30A in the longitudinal direction D2. One scribe line SL1 is located between the front-side metal body 30A located in the nth column and the front-side metal body 30A located in the (n + 1)th column. Each of the (M - 1) scribe lines SL2 is located between adjacent front-side metal bodies 30A in the short-side direction D1. One scribe line SL2 is located between the front-side metal body 30A located in the mth row and the front-side metal body 30A located in the (m + 1)th row.

[0038] The total number of the front-side metal bodies 30A arranged in the short-side direction D1 and the total number of the front-side metal bodies 30A arranged in the longitudinal direction D2 are set according to the size of the ceramic plate 20 and the size of the front-side metal body 30A (back-side metal body 30B). M and N may be the same value, M may be smaller than N, or M may be larger than N. (M, N) may be (3, 3), (3, 4), or (4, 5).

[0039] Different from the examples shown in FIGS. 1, 2, and 5, another scribe line for providing a margin region in the outer peripheral portion of the ceramic plate 20 may be formed between the outer edge of the ceramic plate 20 and the front-side metal body 30A.

[0040] A solder resist may be formed on a part of the surface (upper surface) of the front-side metal body 30A, or plating may be applied. After the ceramic composite substrate 10 is separated into individual pieces, a chip (electronic component) may be joined to the front-side metal body 30A. When joining the chip, a joining material such as solder or a paste containing Ag nanoparticles is applied to the exposed portion of the surface of the front-side metal body 30A. A solder resist or the like may not be formed on the back-side metal body 30B, and the entire outer surface (upper surface and side surfaces) thereof may be exposed. The back-side metal body 30B may function as a heat sink in a power module or the like.

[0041] <Warpage of the ceramic composite substrate 10> From the viewpoint of the coatability of a joining material such as solder to the front-side metal body 30A, the ceramic composite substrate 10 is formed such that an evaluation value indicating the degree of warpage of the ceramic composite substrate 10 is within a predetermined allowable range. Hereinafter, the "warpage" of the ceramic composite substrate 10 will be described. When a scribe line is formed on the front surface 20A and no scribe line is formed on the back surface 20B, it has been found that the ceramic composite substrate 10 as a whole tends to warp so as to protrude in the direction from the back surface 20B toward the front surface 20A.

[0042] Hereinafter, for convenience of explanation, the direction from the back surface 20B toward the front surface 20A will be referred to as "up", and the direction from the front surface 20A toward the back surface 20B will be referred to as "down". It has been found that when a scribe line is formed on the front surface 20A of the ceramic composite substrate 10, the central portion thereof tends to warp (protrude) upward. The warpage of the ceramic composite substrate 10 can be evaluated separately as the warpage of the ceramic plate 20 in the short-side direction D1 and the warpage of the ceramic plate 20 in the long-side direction D2. FIG. 7(a) shows a cross section of the ceramic composite substrate 10 warped so as to protrude (upward) from the back surface 20B toward the front surface 20A.

[0043] In FIG. 7(a), an evaluation line EL is shown that linearly connects both ends of the ceramic plate 20 (more specifically, both ends of the back surface 20B) at the shortest distance in the direction of evaluating warpage. The evaluation line EL is a reference (reference line) when evaluating warpage, and when the contour 28B of the back surface 20B coincides with the evaluation line EL, the ceramic plate 20 is evaluated as not being warped. The contour 28B corresponds to the edge of the back surface 20B in a cross-section obtained by cutting the ceramic plate 20 with a plane passing through the evaluation line EL and along the thickness direction of the ceramic plate 20. FIG. 7(b) illustrates the evaluation line EL and the contour 28B of the back surface 20B with other elements omitted.

[0044] In the present disclosure, when the point located at the uppermost position of the contour 28B is located above the evaluation line EL, it is defined as being warped in a state of protruding upward. Also, when the point located at the uppermost position of the contour 28B is not located above the evaluation line EL (when it coincides with the evaluation line EL), it is defined as being warped in a state of protruding downward. The state of protruding upward can be rephrased as being convexly warped, and the state of protruding downward can be rephrased as being concavely warped.

[0045] In the example shown in FIG. 7(b), throughout the entire evaluation line EL, the contour 28B is located above the evaluation line EL. That is, throughout the entire evaluation line EL, the contour 28B (the ceramic plate 20) protrudes upward. Since the point located at the uppermost position of the contour 28B shown in FIG. 7(b) is located above the evaluation line EL, based on the above definition, it is evaluated as being in a state of protruding upward.

[0046] In FIGS. 8(a) and 8(b), warp states different from the example shown in FIG. 7(b) are illustrated. In the example shown in FIG. 8(a), in a part of the evaluation line EL, a part of the contour 28B is located above the evaluation line EL. That is, in a part of the evaluation line EL, the contour 28B (ceramic plate 20) protrudes upward. In the remaining part of the evaluation line EL, the remaining part of the contour 28B is located below the evaluation line EL. Since the uppermost point of the contour 28B is located above the evaluation line EL, the warp state shown in FIG. 8(a) is evaluated as a state of protruding upward based on the above definition.

[0047] In the example shown in FIG. 8(b), the contour 28B is located below the evaluation line EL throughout the evaluation line EL. That is, the contour 28B (ceramic plate 20) protrudes downward throughout the evaluation line EL. In the example shown in FIG. 8(b), the uppermost point of the contour 28B is not located above the evaluation line EL. Therefore, the warp state shown in FIG. 8(b) is evaluated as a state of protruding downward based on the above definition.

[0048] When evaluating the warp in the short-side direction D1, the warp is evaluated with reference to an evaluation line EL1 (first evaluation line) that connects both ends of the back surface 20B in the short-side direction D1 with a straight line. As shown in FIG. 5, the evaluation line EL1 is set to extend parallel to the short-side direction D1. The evaluation line EL1 is set at the following positions. Note that at the following positions, the front-side metal body 30A can be replaced with the back-side metal body 30B. When N is an even number: between the front-side metal body 30A in the (N / 2)th column and the front-side metal body 30A in the (N / 2 + 1)th column When N is an odd number: between the front-side metal body 30A in the (N / 2 - 0.5)th column and the front-side metal body 30A in the (N / 2 + 0.5)th column

[0049] In the example shown in FIG. 5, since N is 4, an evaluation line EL1 is set between the front-side metal body 30A in the second column and the front-side metal body 30A in the third column. In FIG. 5, although shown in a displaced state, the position of the evaluation line EL1 in the longitudinal direction D2 may substantially coincide with the position of the scribe line SL1 formed on the opposite surface 20A. The ceramic plate 20 (ceramic composite substrate 10) protrudes upward from the back surface 20B toward the front surface 20A at least in a part of the evaluation line EL1. That is, when evaluating the warp with the evaluation line EL1 as a reference, the contour 28B protrudes upward over the entire evaluation line EL1, or a part of the contour 28B protrudes upward in a part of the evaluation line EL1.

[0050] Here, an evaluation value indicating the degree of warp at the evaluation line EL1 is defined as the "first warp amount WA1", and the first warp amount WA1 (absolute value) is defined as follows. First warp amount WA1: The amount obtained by dividing the difference between the maximum value and the minimum value of the back surface 20B (contour 28B) in the first height direction H1 orthogonal to the evaluation line EL1 by the length of the evaluation line EL1

[0051] The first height direction H1 is a direction orthogonal to the evaluation line EL1 in a cross section cut along the thickness direction of the ceramic plate 20 passing through the evaluation line EL1. The first warp amount WA1 is 0.20×10 -2 or less. From the viewpoint of further improving the coatability of the bonding material, the first warp amount WA1 may be 0.16×10 -2 or less, and may be 0.14×10 -2 or less. The first warp amount WA1 is 0.050×10 -2 or more. From the viewpoint of manufacturing ease, the first warp amount WA1 may be 0.055×10 -2 or more, and may be 0.060×10 -2 or more. The first warp amount WA1 is 0.05% to 0.2%.

[0052] Here, the calculation process of the first warpage amount WA1 will be described with reference to FIG. 7(b). In FIG. 7(b), the maximum value of the height of the contour 28B in the first height direction H1 is indicated by "point A", and the minimum value of the height of the contour 28B in the first height direction H1 is indicated by "point B". In this case, point B is at both ends of the contour 28B (both ends of the evaluation line EL). The difference between the maximum value and the minimum value of the height of the contour 28B is indicated by "Dab", and the difference Dab is the distance along the first height direction H1 between point A and point B. By dividing the difference Dab by the length of the evaluation line EL1, the above-described first warpage amount WA1 is obtained.

[0053] When evaluating the warpage in the longitudinal direction D2, the warpage is evaluated based on an evaluation line EL2 (second evaluation line) that connects both ends of the back surface 20B in the longitudinal direction D2 with a straight line. As shown in FIG. 5, the evaluation line EL2 is set to extend parallel to the longitudinal direction D2. The evaluation line EL2 is set at the following positions. At the following positions, the front-side metal body 30A can be replaced with the back-side metal body 30B. When M is an even number: between the front-side metal body 30A in the (M / 2)th row and the front-side metal body 30A in the (M / 2 + 1)th row When M is an odd number: between the front-side metal body 30A in the (M / 2 - 0.5)th row and the front-side metal body 30A in the (M / 2 + 0.5)th row

[0054] In the example shown in FIG. 5, since M is 3, the evaluation line EL2 is set between the front-side metal body 30A in the first row and the front-side metal body 30A in the second row. In FIG. 5, although shown in a displaced state, the position of the evaluation line EL2 in the short-side direction D1 may substantially coincide with the position of the scribeline SL2 formed on the opposite surface 20A. The ceramic plate 20 (ceramic composite substrate 10) may protrude upward from the back surface 20B toward the surface 20A at at least a part of the evaluation line EL2. Or, the ceramic plate 20 (ceramic composite substrate 10) may protrude downward from the surface 20A toward the back surface 20B at the evaluation line EL2.

[0055] Here, the evaluation value indicating the degree of warpage at the evaluation line EL2 is defined as the "second warpage amount WA2", and the second warpage amount WA2 (absolute value) is defined as follows. Second warpage amount WA2: The amount obtained by dividing the difference between the maximum value and the minimum value of the back surface 20B (profile 28B) in the second height direction H2 orthogonal to the evaluation line EL2 by the length of the evaluation line EL2

[0056] The second height direction H2 is the direction orthogonal to the evaluation line EL2 in the cross section cut along the thickness direction of the ceramic plate 20 passing through the evaluation line EL2. The second warpage amount WA2 may be 0.10×10 -2 or less (it may be 0.10% or less), and may be smaller than 0.10×10 -2 From the viewpoint of further improving the coatability of the bonding material, the second warpage amount WA2 may be 0.08×10 -2 or less, may be 0.06×10 -2 or less, may be 0.04×10 -2 or less. Depending on whether the ceramic plate 20 protrudes upward or downward at the evaluation line EL2, the range of the second warpage amount WA2 may be different. When the ceramic plate 20 protrudes upward, the second warpage amount WA2 may be 0.10×10 -2 or less, or may be smaller than 0.10×10 -2 When the ceramic plate 20 protrudes downward, the second warpage amount WA2 may be 0.05×10 -2 or less, may be 0.04×10 -2 or less, may be 0.02×10 -2 or less.

[0057] Here, the calculation process of the second warpage amount WA2 will be described with reference to FIGS. 8(a) and 8(b). In each of FIGS. 8(a) and 8(b), the maximum value of the height of the contour 28B in the second height direction H2 is indicated by "point C", and the minimum value of the height of the contour 28B in the second height direction H2 is indicated by "point D". The difference between the maximum value and the minimum value of the height of the contour 28B in the second height direction H2 is indicated by "Dcd", and the difference Dcd is the distance along the second height direction H2 between point C and point D. By dividing the difference Dcd by the length of the evaluation line EL2, the above-mentioned second warpage amount WA2 is obtained.

[0058] When N is odd, the position of the evaluation line EL1 may vary depending on which front-side metal body 30A located at a corner is set in the first column. In this case, regardless of the position where the evaluation line EL1 is set, the ceramic composite substrate 10 is formed such that the first warpage amount WA1 satisfies the above range. Similarly, when M is odd, the position of the evaluation line EL2 may vary depending on which front-side metal body 30A located at a corner is set in the first row. In this case, regardless of the position where the evaluation line EL2 is set, the ceramic composite substrate 10 is formed such that the second warpage amount WA2 satisfies the above range.

[0059] [Manufacturing Method] (Fabrication of Ceramic Plate) Subsequently, an example of a method for manufacturing a circuit board including the manufacturing process of the ceramic composite substrate 10 will be described. In this method for manufacturing a circuit board, first, a ceramic plate 20 is fabricated. In the fabrication process of the ceramic plate 20, a ceramic plate 20 containing a ceramic material (for example, silicon nitride powder or aluminum nitride powder) is fabricated. The ceramic plate 20 can be manufactured, for example, by the following procedure. First, a slurry containing silicon nitride powder or aluminum nitride powder, a sintering aid, and a binder resin is molded to obtain a green sheet. The above slurry may contain a plasticizer, a dispersant, a solvent, and the like.

[0060] Examples of sintering aids include rare earth metals, alkaline earth metals, metal oxides, fluorides, chlorides, nitrates, and sulfates, etc. These may be used alone or in combination of two or more. By using a sintering aid, sintering of the inorganic compound powder can be promoted. Examples of binder resins include methyl cellulose, ethyl cellulose, polyvinyl alcohol, polyvinyl butyral, and (meth)acrylic resins, etc.

[0061] Examples of plasticizers include phthalate plasticizers such as refined glycerin, glycerin trioleate, diethylene glycol, di-n-butyl phthalate, etc., and dibasic acid plasticizers such as di-2-ethylhexyl sebacate, etc. Examples of dispersants include poly(meth)acrylate, and (meth)acrylic acid-maleic acid salt copolymer, etc. Examples of solvents include organic solvents such as ethanol and toluene.

[0062] Examples of slurry forming methods include the doctor blade method and the extrusion molding method. A green sheet is produced by such methods. Thereafter, debinding and sintering of the green sheet are performed to obtain a ceramic plate 20 containing silicon nitride or aluminum nitride. Debinding may be carried out, for example, by heating the green sheet at 400°C to 800°C for 0.5 to 20 hours. This can reduce the residual amount of organic matter (carbon) while suppressing oxidation and deterioration of silicon nitride or aluminum nitride. Sintering may be carried out by heating the green sheet at 1700°C to 1900°C in a non-oxidizing gas atmosphere such as nitrogen, argon, ammonia or hydrogen.

[0063] The above degreasing and sintering may be performed in a state where a plurality of green sheets are laminated. When performing degreasing and sintering after lamination, a release layer made of a release agent may be provided between the green sheets in order to smoothly separate the sheets after firing. As the release agent, for example, boron nitride (BN) can be used. The release layer may be formed, for example, by applying a slurry of boron nitride powder by a method such as spraying, brushing, roll coating, or screen printing. The number of green sheets to be laminated may be, for example, 10 to 100 sheets, or 20 to 80 sheets from the viewpoint of efficiently mass-producing the base material while allowing sufficient progress of degreasing.

[0064] (Formation of scribing lines) After the manufacturing process of the ceramic plate 20, a process of forming scribing lines is performed. In this process, scribing lines are formed on the surface 20A, which is one main surface of the ceramic plate 20, using laser light according to predetermined processing conditions. Specifically, scribing lines SL1 and SL2 are formed by irradiating the surface 20A of the ceramic plate 20 with laser light to form a plurality of holes 24. FIG. 9(a) illustrates the ceramic plate 20 in a state where the scribing lines SL1 and SL2 are formed.

[0065] Examples of the laser light include carbon dioxide lasers, YAG lasers, and fiber lasers. Each of the plurality of holes 24 may be formed by a single irradiation of laser light or by a plurality of irradiations of laser light. The holes 24 may be formed in burst pulse mode or in cycle pulse mode. The scribing lines SL1 and SL2 serve as cutting lines when dividing the composite substrate including the ceramic plate 20 in a subsequent process. By forming the scribing lines SL1 and SL2, a plurality of partition portions 22 in a two-dimensional array state are formed on the ceramic plate 20.

[0066] (Bonding of metal plates) Next, a step of applying a paste-like brazing material to the front surface 20A and the back surface 20B of the ceramic plate 20 is performed. For example, the paste-like brazing material is applied to the front surface 20A and the back surface 20B by a method such as a roll coater method, a screen printing method, or a transfer method. The brazing material contains, for example, Ag (silver), Cu (copper), and an active metal. The composition ratio of Ag and Cu may be set to a composition ratio that easily forms a eutectic composition. In a total of 100 parts by mass of Ag powder and Cu powder, the Ag powder may be 75 to 100 parts by mass, and the Cu powder may be 0 to 25 parts by mass.

[0067] The active metal contains at least one selected from titanium, zirconium, hafnium, and niobium. The amount of the active metal contained in the brazing material may be 0.5 to 6.0 parts by mass with respect to 100 parts by mass in total of the Ag powder and the Cu powder. The brazing material may contain at least one selected from In (indium), Zn (zinc), Cd (cadmium), and Sn (tin). The amount of In or the like contained in the brazing material layer may be 0.4 to 5.0 parts by mass with respect to 100 parts by mass in total of the Ag powder and the Cu powder. The tap density (JIS Z 2512) of the Ag powder contained in the brazing material may be 3 g / cm 3 or more. The thickness of the brazing material during drying may be 5 μm to 40 μm.

[0068] Next, as shown in FIG. 9(b), a pair of metal plates 38A and 38B are joined to the ceramic plate 20 in a state where the brazing material is applied to both the front surface 20A and the back surface 20B. In this joining, one metal plate 38A is bonded to the front surface 20A of the ceramic plate 20 to which the brazing material is applied, and one metal plate 38B is bonded to the back surface 20B, whereby a joined body is obtained. Then, the joined body is heated in a heating furnace while applying a load thereto, so that the pair of metal plates are joined to the ceramic plate 20.

[0069] The heating of the joined body is, for example, a vacuum degree of 1.0×10 -3It is carried out in a substantially vacuum state of less than Pa. The heating temperature may be 700 °C to 850 °C, and the heating time may be 10 minutes to 60 minutes. With a pair of metal plates 38A and 38B sandwiching the ceramic plate 20, in the direction in which the metal plates 38A and 38B face the ceramic plate 20, the load applied to the joined body during heating may be 0.02 MPa to 0.10 MPa. The joined body is heated and after being taken out from the heating furnace, the joined body is cooled to about room temperature.

[0070] After cooling, as shown in FIG. 9(c), warpage occurs such that the central portion of the joined body protrudes upward. It is considered that one of the factors for the central portion to protrude upward is that a difference occurs between the force received by one metal plate from the ceramic plate 20 and the force received by the other metal plate from the ceramic plate 20 during cooling due to the difference in the presence or absence of scribe lines between the front surface 20A and the back surface 20B.

[0071] (Formation of a plurality of metal bodies) Next, etching is performed to divide each of the pair of metal plates into a plurality of front-side metal bodies 30A and a plurality of back-side metal bodies 30B. For example, as shown in FIG. 10(a), on the metal plate 38A joined to the front surface 20A, an etching resist Er is printed in areas other than the areas where each of the plurality of front-side metal bodies 30A is formed, and on the metal plate 38B joined to the back surface 20B, an etching resist Er is printed in the areas where each of the plurality of back-side metal bodies 30B is formed.

[0072] Then, as shown in FIG. 10(b), the metal plates 38A and 38B are etched so that the portions where the etching resist Er is not printed are removed. Thereby, a ceramic composite substrate 10 is obtained in a state where one front-side metal body 30A and one back-side metal body 30B are formed in each of the plurality of partition portions 22.

[0073] (Warpage evaluation) Next, on each of the evaluation lines EL1 and EL2, the warpage of the ceramic composite substrate 10 is evaluated. That is, the manufacturing process of the ceramic composite substrate 10 includes a warpage evaluation process. In the evaluation of the warpage in the short side direction D1 of the ceramic composite substrate 10 (ceramic plate 20), the evaluation line EL1 is set. The evaluation line EL1 extends parallel to the short side direction D1 and is set to be located between the front side metal body 30A in the (N / 2)th column and the front side metal body 30A in the (N / 2 + 1)th column, or between the front side metal body 30A in the (N / 2 - 0.5)th column and the front side metal body 30A in the (N / 2 + 0.5)th column.

[0074] On at least a part of the evaluation line EL1, it is evaluated whether the ceramic plate 20 is warped upward. For example, in the first height direction H1 orthogonal to the evaluation line EL1, it is evaluated whether the point where the height of the back surface 20B is maximum is located above the evaluation line EL1. Also, the first warpage amount WA1 is calculated by dividing the difference between the maximum value and the minimum value of the back surface 20B (profile 28B) in the first height direction H1 by the length of the evaluation line EL1. Then, it is determined whether the first warpage amount WA1 is within a predetermined allowable range (0.05×10 -2 ~0.2×10 -2 ). When the ceramic plate 20 is warped downward on the evaluation line EL, or when it is evaluated that the ceramic plate 20 is warped upward and the first warpage amount WA1 is outside the predetermined allowable range, the ceramic composite substrate 10 to be evaluated may be excluded as a non-conforming product.

[0075] In the evaluation of the warpage in the longitudinal direction D2 of the ceramic composite substrate 10 (ceramic plate 20), the evaluation line EL2 is set. The evaluation line EL2 extends parallel to the longitudinal direction D2 and is set to be located between the front side metal body 30A in the (M / 2)th row and the front side metal body 30A in the (M / 2 + 1)th row, or between the front side metal body 30A in the (M / 2 - 0.5)th row and the front side metal body 30A in the (M / 2 + 0.5)th row.

[0076] Then, the second warpage amount WA2 described above is calculated by dividing the difference between the maximum value and the minimum value of the back surface 20B (contour 28B) in the second height direction H2 orthogonal to the evaluation line EL2 by the length of the evaluation line EL2. Thereafter, it is determined whether the second warpage amount WA2 is within a predetermined allowable range (a range smaller than 0.1×10 -2 ). When the second warpage amount WA2 is out of the predetermined allowable range, the ceramic composite substrate 10 to be evaluated may be excluded as a non-conforming product.

[0077] FIGS. 11(a) and 11(b) show an example of a graph obtained in the process of calculating the first warpage amount WA1 and the second warpage amount WA2. Since the calculation of the warpage amount at the evaluation line EL1 and the evaluation line EL2 is performed in the same manner except for the setting position of the reference line, hereinafter, the evaluation lines EL1 and EL2 will be collectively referred to as the evaluation line EL for explanation.

[0078] First, with the back surface 20B facing upward and the front surface 20A facing downward, the ceramic composite substrate 10 to be evaluated is set on the measuring table. Then, using a contact-type two-dimensional contour measuring machine (for example, "Contour Record 1600G" manufactured by Tokyo Seimitsu Co., Ltd.), starting from one end of the evaluation line EL1, the contour shape of the back surface 20B is measured along the evaluation line EL to the other end. FIG. 11(a) illustrates a graph Gr1 obtained by plotting the measurement data by the measuring machine. Next, the inclination correction of the measurement data is performed so that the line segment (corresponding to the evaluation line EL) connecting the two points at both ends of the measurement data in the graph Gr1 is horizontal on the scale. FIG. 11(b) illustrates the graph Gr2 after the inclination correction.

[0079] In the corrected graph Gr2, the height positions at the graduations at both ends of the measurement data are substantially the same. Then, in the corrected graph Gr2, two points with the largest height difference are extracted as the maximum value and the minimum value, and the height difference (the above-mentioned difference Dab or difference Dcd) is measured. Thereafter, by dividing the height difference by the length of the evaluation line EL, the first warpage amount WA1 or the second warpage amount WA2 is calculated. The length of the evaluation line EL may be measured by another method or may be measured from the corrected graph Gr2. In the measurement of the contour of the contour 28B, a device that detects the contour shape by laser irradiation may be used instead of the contact type two-dimensional contour measuring machine.

[0080] (Solder resist·Individualization) Next, as shown in FIG. 10(c), in each of the plurality of front-side metal bodies 30A, a solder resist Sr is formed in a portion other than the region where the chip is mounted (around the mounting region). No solder resist is formed on each of the plurality of back-side metal bodies 30B. Then, as shown in FIG. 10(d), by dividing the ceramic composite substrate 10 along the scribe lines SL1 and SL2, a divided substrate 50 (circuit board) in an individualized state is obtained. Thereafter, chips are mounted on the front-side metal bodies 30A included in the divided substrate 50.

[0081] [Effects of the Embodiment] In the ceramic composite substrate 10 described above, in at least a part of the evaluation line EL1 extending along the short side direction D1, the ceramic plate 20 protrudes upward from the back surface 20B toward the front surface 20A, and the first warpage amount WA1 is 0.05×10 -2 ~0.2×10 -2 That is. In this case, when the ceramic composite substrate 10 is individualized, the warpage amount when the individualized divided substrate 50 warps upward and the warpage amount when the divided substrate 50 warps downward are reduced. Therefore, when applying a bonding material such as solder or a paste containing Ag nanoparticles to the surface of the front-side metal body 30A by screen printing or the like on the divided substrate 50, it is difficult for non-coated portions to occur. Also, the first warpage amount WA1 is 0.2×10 -2Therefore, even when the bonding material is applied in the state of the ceramic composite substrate 10, it is difficult for uncoated portions to occur. Therefore, the ceramic composite substrate 10 is useful for improving the coatability of the bonding material to the metal body.

[0082] In the ceramic composite substrate 10, the second warpage amount WA2 may be smaller than 0.1×10 -2 Even in this case, since the warpage amount of the ceramic plate 20 is small also in the longitudinal direction D2, it is more difficult for uncoated portions to occur when the bonding material is applied, in either the state of the composite substrate (before being separated into individual pieces) or the state after being separated into individual pieces. Therefore, it is more useful for improving the coatability of the bonding material to the metal body.

[0083] In the ceramic composite substrate 10, the volume ratio of the metal body may be 0.95 to 1.05. In this case, the warpage amount at the time of being separated into individual pieces tends to be small. Therefore, it is more useful for improving the coatability of the bonding material to the metal body.

Example

[0084] Next, the content of the present disclosure will be described in more detail with reference to examples and comparative examples, but the present disclosure is not limited to the following examples.

[0085] (Example 1) By the manufacturing method described above, a ceramic composite substrate 10 was formed in a state where a plurality of front-side metal bodies 30A and a plurality of back-side metal bodies 30B were formed on both main surfaces of a ceramic plate 20 whose main surface is rectangular. Specifically, a silicon nitride plate having a short-side length of 126 mm and a long-side length of 168 mm was produced. Scribe lines SL1 and SL2 were formed on the surface 20A of the ceramic plate 20 which is a silicon nitride plate. The scribe lines SL1 and SL2 were formed so as to be partitioned into a plurality of partition portions 22 of 3 rows and 4 columns (where M is 3 and N is 4).

[0086] The processing conditions were set as follows to form scribe lines SL1 and SL2. The array pitch p was set to 60 μm, the aperture diameter r of the holes 24 was set to 70 μm, and the depth d of the holes 24 was set to 70 μm. The three-point bending strength (JIS R 1601-2008) measured on the scribe line was 396 MPa. The three-point bending strength was measured by applying a load at a position corresponding to the scribe line on the surface opposite to the main surface on which the scribe line was formed, with the scribe line of the evaluation target facing downward and supported at two points sandwiching the scribe line. In the selection of the evaluation target, the ceramic composite substrate 10 was divided into a plurality of composite substrates (a plurality of two-piece substrates) including two partition portions 22. Then, three two-piece substrates were randomly extracted from the plurality of two-piece substrates, and the scribe lines formed on these two-piece substrates were taken as the evaluation targets. Thereafter, the average of the measured values of the three-point bending strength obtained for each of the three two-piece substrates was determined to evaluate the three-point bending strength. Next, a pair of copper plates (metal plates 38A and 38B) were attached to both main surfaces of the ceramic plate 20 via a brazing material to obtain a joined body. While applying a load of 0.04 MPa to the joined body, the joined body was heated at 800°C in a vacuum state.

[0087] After cooling the heated joined body, etching was performed on the pair of copper plates so that a front-side metal body 30A of three rows and four columns and a back-side metal body 30B of three rows and four columns were formed. The length of the front-side metal body 30A in the direction along the short side of the ceramic plate 20 was set to 40 mm, and the length of the front-side metal body 30A in the direction along the long side of the ceramic plate 20 was set to 40 mm. The length of the back-side metal body 30B in the direction along the short side of the ceramic plate 20 was set to 40 mm, and the length of the back-side metal body 30B in the direction along the long side of the ceramic plate 20 was set to 40 mm.

[0088] A gap of 1 mm was provided between the front-side metal body 30A (back-side metal body 30B) and the scribe lines SL1 and SL2. The ratio of the volume of the corresponding front-side metal body 30A to the volume of the back-side metal body 30B (the volume ratio of the above-mentioned metal bodies) was set to 1. When evaluating the warp in the short-side direction D1, it protruded upward, and the first warp amount WA1 along the evaluation line EL1 was 0.12% (0.12×10-2 ) It was. When evaluating the warp in the longitudinal direction D2, it protruded upward, and the second warp amount WA2 along the evaluation line EL2 was 0.03% (0.03×10 -2 ) It was.

[0089] (Example 2) A ceramic composite substrate 10 was manufactured in the same manner as in Example 1, except that the array pitch p of the scribe lines was changed to 40 μm and the load during bonding was changed to 0.02 MPa. The three-point bending strength was 363 MPa. It warped upward at the evaluation lines EL1 and EL2, the first warp amount WA1 was 0.15%, and the second warp amount WA2 was 0.04%.

[0090] (Example 3) A ceramic composite substrate 10 was manufactured in the same manner as in Example 1, except that the array pitch p of the scribe lines was changed to 80 μm. The three-point bending strength was 441 MPa. It warped upward at the evaluation line EL1 and warped downward at the evaluation line EL2. The first warp amount WA1 was 0.06%, and the second warp amount WA2 was 0.01%.

[0091] (Example 4) A ceramic composite substrate 10 was manufactured in the same manner as in Example 1, except that the volume ratio of the metal body was changed to 0.86. To make the volume ratio of the metal body 0.86, the size of the front-side metal body 30A was changed to 37 mm × 37 mm. The three-point bending strength was 396 MPa. It warped upward at the evaluation lines EL1 and EL2, the first warp amount WA1 was 0.18%, and the second warp amount WA2 was 0.08%.

[0092] (Example 5) A ceramic composite substrate 10 was manufactured in the same manner as in Example 1, except that the size of the ceramic plate 20 was changed to 168 mm × 210 mm and the number of divisions was changed to 4×5. The three-point bending strength was 396 MPa. It warped upward at the evaluation lines EL1 and EL2, the first warp amount WA1 was 0.13%, and the second warp amount WA2 was 0.02%.

[0093] (Example 6) A ceramic composite substrate 10 was manufactured in the same manner as in Example 1, except that the array pitch p of the scribing lines was changed to 100 μm and the depth d of the holes 24 was changed to 100 μm. The three-point bending strength was 383 MPa. It was warped upward at the evaluation lines EL1 and EL2, the first warpage amount WA1 was 0.11%, and the second warpage amount WA2 was 0.04%.

[0094] (Example 7) A ceramic composite substrate 10 was manufactured in the same manner as in Example 1, except that the temperature of the bonding conditions was changed to 850°C. The three-point bending strength was 396 MPa. It was warped upward at the evaluation lines EL1 and EL2, the first warpage amount WA1 was 0.12%, and the second warpage amount WA2 was 0.03%.

[0095] (Comparative Example 1) A ceramic composite substrate 10 was manufactured in the same manner as in Example 1, except that the load of the bonding conditions was changed to 0.01 MPa. The three-point bending strength was 396 MPa. It was warped upward at the evaluation lines EL1 and EL2, the first warpage amount WA1 was 0.35%, and the second warpage amount WA2 was 0.10%.

[0096] (Comparative Example 2) A ceramic composite substrate 10 was manufactured in the same manner as in Example 1, except that the array pitch p was changed to 90 μm and the load of the bonding conditions was changed to 0.02 MPa. The three-point bending strength was 463 MPa. It was warped upward at the evaluation lines EL1 and EL2, the first warpage amount WA1 was 0.03%, and the second warpage amount WA2 was 0.02%.

[0097] Examples 1 to 7 and Comparative Examples 1 and 2 above are shown in Tables 1 and 2. In Table 2, a “(+)” is attached to the warpage amount when protruding upward, and a “(-)” is attached to the warpage amount when protruding downward. The value of the warpage amount itself is an absolute value. In Examples 1 to 7, since it warps upward in the short side direction D1 and the warpage amount is small, the coatability of the bonding material to the plurality of front side metal bodies 30A in the state of the ceramic composite substrate 10 can be improved.

[0098]

Table 1

[0099]

Table 2

[0100] <Verification of warpage amount in the fragmented state> Table 3 shows the verification results of the degree of warpage in the fragmented state for Examples 1 to 7 and Comparative Examples 1 and 2. When the evaluation value indicating the degree of warpage in the fragmented state is defined as the “third warpage amount WA3”, the third warpage amount WA3 (absolute value) is defined as follows. Third warpage amount WA3: The amount obtained by dividing the difference between the maximum value and the minimum value of the upper surface (the contour of the upper surface of the front side metal body 30A) of the front side metal body 30A in the third height direction H3 orthogonal to the evaluation line ELx by the length of the evaluation line ELx

[0101]

Table 3

[0102] The evaluation line ELx is a line that linearly connects the outer edges of the surface 20A so as to extend obliquely on the upper surface of one front-side metal body 30A (see Fig. 5). Except for the points where the shape on the upper surface of the front-side metal body 30A is measured instead of the contour 28B of the back surface 20B, the third warpage amount WA3 is calculated in the same manner as the first warpage amount WA1 and the second warpage amount WA2. The meanings of “(+)” and “(-)” in Table 3 are the same as those in the columns of the first warpage amount WA1 and the second warpage amount WA2 in Table 1.

[0103] In Table 3, n = 1 to 5 means that five individual pieces (divided substrates) are the objects of warpage evaluation. Here, four divided substrates located at the corners of the surface 20A of the ceramic plate 20 and one divided substrate located at the central portion of the surface 20A are the evaluation objects. n = 1, 2, 4, 5 are the evaluation results of the four divided substrates located at the corners of the surface 20A, and n = 3 is the evaluation result of the divided substrate located at the central portion. The average value is the value obtained by averaging the five third warpage amounts WA3 by the number. When protruding downward, the value of the third warpage amount WA3 is made negative to calculate the average value. When protruding downward, the value of the third warpage amount WA3 is made negative, and the difference between the maximum third warpage amount WA3 and the minimum third warpage amount WA3 is calculated as the variation.

[0104] From the verification results in Table 3, it can be seen that if the first warpage amount WA1 is 0.20% or less, unlike Comparative Example 1, the third warpage amount WA3 in all of the five evaluation objects is within 0.15%. Also, if the first warpage amount WA1 is greater than 0.05%, unlike Comparative Example 2, all the third warpage amounts WA3 of the five evaluation objects satisfy the condition of being within 0.15% when protruding upward on the evaluation line ELx and within 0.05% when protruding downward on the evaluation line ELx. When applying the bonding material to the metal body, it may be easier to apply when protruding upward rather than downward. However, even if it protrudes downward, by suppressing the warpage amount to 0.05% or less, a decrease in coatability can be avoided.

[0105] It can be seen that the variation in the third warpage amount WA3 in Examples 1 to 7 is smaller than the variation in the third warpage amount WA3 in Comparative Examples 1 and 2. Comparing Example 4 with a volume ratio of the metal body of 0.86 and Examples 1 to 3, 5 to 7 with a volume ratio of the metal body of 1, it can be seen that the average value of the third warpage amount WA3 in the other examples is smaller than the average value of the third warpage amount WA3 in Example 4.

Explanation of Signs

[0106] 10... Ceramic composite substrate, 20... Ceramic plate, 20A... Front surface, 20B... Back surface, 30A... Front-side metal body, 30B... Back-side metal body, SL1, SL2... Scribe lines, EL1, EL2... Evaluation lines, H1... First height direction, H2... Second height direction.

Claims

1. A ceramic plate having a first main surface and a second main surface, a plurality of first metal bodies formed to be two-dimensionally arranged in M rows and N columns (M and N are integers of 2 or more) on the first main surface, a plurality of second metal bodies formed to be two-dimensionally arranged at positions corresponding to the plurality of first metal bodies on the second main surface, one or more first scribe lines formed on the first main surface, which are located between adjacent first metal bodies among the N first metal bodies arranged in the longitudinal direction of the ceramic plate and extend along the short side direction of the ceramic plate, one or more second scribe lines formed on the first main surface, which are located between adjacent first metal bodies among the M first metal bodies arranged in the short side direction and extend along the longitudinal direction, and no scribe line is formed on the second main surface, at least a part of a predetermined first evaluation line set to connect both ends of the second main surface in the short side direction by a straight line, the ceramic plate protrudes in a direction from the second main surface toward the first main surface, when an amount obtained by dividing a difference between a maximum value and a minimum value of the second main surface in a first height direction orthogonal to the first evaluation line by a length of the first evaluation line is defined as a first warpage amount, the first warpage amount is 0.05×10 －２ ~0.2×10 －２ and the first evaluation line is when N is an even number, set between the first metal body in the (N / 2)th column and the first metal body in the (N / 2 + 1)th column, when N is an odd number, set between the first metal body in the (N / 2 - 0.5)th column and the first metal body in the (N / 2 + 0.5)th column, When defining the difference between the maximum value and the minimum value of the second main surface in the second height direction perpendicular to a predetermined second evaluation line set to connect both ends of the second main surface in the longitudinal direction by a straight line as an amount obtained by dividing by the length of the second evaluation line as the second warpage amount, the second warpage amount is less than 0.1×10−2, The second evaluation line is When M is an even number, it is set between the first metal bodies in the (M / 2)th row and the first metal bodies in the (M / 2 + 1)th row, When M is an odd number, it is set between the first metal bodies in the (M / 2 - 0.5)th row and the first metal bodies in the (M / 2 + 0.5)th row, a ceramic composite substrate.

2. The ratio of the volume of the first metal body located at m rows and n columns to the volume of the second metal body located at m rows and n columns is 0.95 to 1.05, m is an integer from 1 to M, and n is an integer from 1 to N, the ceramic composite substrate according to claim 1.

3. A ceramic plate having a first main surface and a second main surface, a plurality of first metal bodies formed in a two-dimensional array in M rows and N columns (M and N are integers of 2 or more) on the first main surface, and a plurality of second metal bodies formed in a two-dimensional array at positions corresponding to the plurality of first metal bodies on the second main surface, located between adjacent first metal bodies among the N first metal bodies arranged in the longitudinal direction of the ceramic plate, and formed on the first main surface so as to extend along the short side direction of the ceramic plate 1 or a plurality of first scribe lines, located between adjacent first metal bodies among the M first metal bodies arranged in the short side direction, and formed on the first main surface so as to extend along the longitudinal direction 1 or a plurality of second scribe lines, a method for manufacturing a ceramic composite substrate having no scribe line formed on the second main surface, A step of evaluating whether or not the ceramic plate protrudes in a direction from the second main surface toward the first main surface at at least a part of a predetermined first evaluation line set to connect both ends of the second main surface in the short side direction by a straight line, When the difference between the maximum value and the minimum value of the second main surface in the first height direction orthogonal to the first evaluation line is divided by the length of the first evaluation line and the resulting quantity is defined as the first warpage amount, whether the first warpage amount is 0.05×10 －２ ~0.2×10 －２ or not is evaluated; When the difference between the maximum value and the minimum value of the second main surface in the second height direction orthogonal to a predetermined second evaluation line set to connect both ends of the second main surface in the longitudinal direction by a straight line is divided by the length of the second evaluation line and the resulting quantity is defined as the second warpage amount, whether the second warpage amount is less than 0.1×10−2 is evaluated; including The first evaluation line is set between the first metal bodies in the (N / 2)th column and the first metal bodies in the (N / 2 + 1)th column when N is an even number, is set between the first metal bodies in the (N / 2 - 0.5)th column and the first metal bodies in the (N / 2 + 0.5)th column when N is an odd number; The second evaluation line is set between the first metal bodies in the (M / 2)th row and the first metal bodies in the (M / 2 + 1)th row when M is an even number, is set between the first metal bodies in the (M / 2 - 0.5)th row and the first metal bodies in the (M / 2 + 0.5)th row when M is an odd number. A method for manufacturing a ceramic composite substrate.

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