Multiple ceramic substrates and method for manufacturing the same

Abstract

To provide a multi-piece ceramic board capable of suppressing waviness of a base end part by suppressing variation of a thickness of an outer peripheral region, and provide a manufacturing method of them.SOLUTION: A multi-piece ceramic board according to the present invention, comprises: a base material that is a rectangular shaped base material formed by laminating a plurality of ceramic layers, and has a first surface and a second surface, in which a substrate region and an outer peripheral region formed to an outer side of the substrate region are included in the first surface and the second surface; a plurality of substrate elements that is formed to at least one part of each substrate region, and includes a conductive pattern for a manufacturing coated by a metal plating layer; a conductive pattern for a plurality of dummies that is formed in one part of each outer peripheral region, and is arranged in a predetermined interval. The conductive pattern for a plurality of dummies formed to each of the first surface and the second surface is formed at a position corresponded to the first surface and the second surface.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a multi-piece ceramic substrate and a method for manufacturing the same.

Background Art

[0002] Patent Document 1 discloses a multi-piece ceramic substrate capable of obtaining individual ceramic substrates by division. This multi-piece ceramic substrate has a substrate region in which a plurality of substrate elements that become individual ceramic substrates are formed, and an outer peripheral region located outside this substrate region. An internal circuit element is formed on each ceramic substrate by a conductor pattern.

[0003] The multi-piece ceramic substrate is manufactured by laminating a plurality of ceramic green sheets on which conductor patterns are printed to form a plate-like laminate, and sintering this plate-like laminate. In such a multi-piece ceramic substrate, in order to suppress warping and deformation of the substrate that may occur during sintering, it has been proposed to form a dummy conductor pattern having the same shape as the product conductor pattern formed in the substrate region in the outer peripheral region.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the dummy conductor patterns are different between the front and back surfaces of the substrate, the balance of shrinkage due to firing on the front and back was poor. Therefore, in the multi-piece ceramic substrate after sintering of the plate-like laminate, the undulation of the outer peripheral region could not be sufficiently suppressed. Therefore, for example, when handling the multi-piece ceramic substrate, stress may concentrate on the undulated portion and the multi-piece ceramic substrate may crack.

[0006] The present invention has been made to solve the above problems, and an object thereof is to provide a multi-piece ceramic substrate and a method for manufacturing the same, which can suppress variations in the thickness of the conductive pattern in the outer peripheral region and thereby suppress undulations in the outer peripheral region after sintering.

Means for Solving the Problems

[0007] The multi-piece ceramic substrate according to the present invention is a rectangular base material formed by laminating a plurality of ceramic layers and having a first surface and a second surface. On each of the first surface and the second surface, there is a base material having a substrate region and an outer peripheral region formed outside the substrate region, and a plurality of substrate elements each having a conductive pattern for a product formed on at least a part of each substrate region and covered with a metal plating layer, and a plurality of dummy conductive patterns formed on at least a part of each outer peripheral region and arranged at a predetermined interval. The plurality of dummy conductive patterns formed on the first surface and the second surface are respectively formed at corresponding positions on the first surface and the second surface.

[0008] In the above multi-piece ceramic substrate, each of the plurality of dummy conductive patterns can be formed in a rectangular shape.

[0009] In the above multi-piece ceramic substrate, the plurality of dummy conductive patterns can be formed in a plurality of rows in a direction from the outer peripheral region toward the substrate region and in a plurality of rows in the circumferential direction of the outer peripheral region.

[0010] In the above multi-piece ceramic substrate, the thickness of the dummy conductive pattern having the smallest thickness among the plurality of dummy conductive patterns can be 75% or more of the thickness of the dummy conductive pattern having the largest thickness.

[0011] In the above multi-piece ceramic substrate, the plurality of dummy conductive patterns can be formed in 70% or more of the circumferential direction of the outer peripheral region.

[0012] In the above-mentioned multiple ceramic substrates, the plurality of dummy conductive patterns can be formed symmetrically on each of the two pairs of opposite sides of the base material.

[0013] In the above-mentioned multiple ceramic substrates, in the outer peripheral region, the dummy conductive patterns can be prevented from being formed at the four corners of the base material.

[0014] In the above-mentioned multiple ceramic substrates, the ratio of the width of the dummy conductive pattern in the direction parallel to one side of the base material to the length of any one side of the base material is 0.5 to 8%, and the ratio of the predetermined interval of the dummy conductive pattern in the direction parallel to one side of the base material to the length of any one side of the base material can be 0.1 to 0.3%.

[0015] The method for manufacturing the above-mentioned multiple ceramic substrates according to the present invention includes the steps of preparing a plurality of ceramic layers including a first ceramic layer and a second ceramic layer, wherein one surface of the first ceramic layer and the second ceramic layer respectively has a substrate region and an outer peripheral region formed outside the substrate region; printing a plurality of substrate elements having conductive patterns for products on at least a part of each of the substrate regions of the first ceramic layer and the second ceramic layer; printing a plurality of dummy conductive patterns arranged at a predetermined interval on at least a part of each of the outer peripheral regions of the first ceramic layer and the second ceramic layer; laminating the plurality of ceramic layers so that one surface of the first ceramic layer and one surface of the second ceramic layer become a first surface and a second surface respectively to form a base material; forming dividing grooves between the substrate region and the outer peripheral region and between the substrate elements on the first surface and the second surface; firing the base material; and forming a metal plating layer so as to cover the conductive pattern for products.

Effects of the Invention

[0016] According to the present invention, it is possible to suppress the variation in the thickness of the dummy conductive pattern in the outer peripheral region, and thereby suppress the undulation in the outer peripheral region of the substrate after sintering. As a result, it is possible to prevent stress from concentrating during the handling of the multi-piece ceramic substrate and prevent the multi-piece ceramic substrate from cracking.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

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Figure 10

Embodiments for Carrying Out the Invention

[0018] Hereinafter, an embodiment of a multi-piece ceramic substrate and a manufacturing method thereof according to the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a multi-piece ceramic substrate according to this embodiment, FIG. 2 is a partially enlarged plan view, and FIG. 3 is a partial cross-sectional view of FIG. 1.

[0019] <1. Multi-piece ceramic substrate> <1-1. Overview of a multi-piece ceramic substrate> As will be described later, from the multi-piece ceramic substrate 1 according to the present embodiment, a plurality of ceramic substrates can be obtained by division. And these ceramic substrates can be used as wiring substrates, circuit boards, etc. of electronic devices.

[0020] As shown in FIGS. 1 to 3, this multi-piece ceramic substrate 1 has a plate-shaped base material 10 formed in a rectangular shape having a first surface 101 and a second surface 102. The first surface 101 and the second surface 102 each have a rectangular substrate region 2 and a frame-shaped outer peripheral region 3 surrounding the periphery thereof. The substrate region 2 and the outer peripheral region 3 have the same shape on the first surface 101 and the second surface 102 and are provided at the same positions.

[0021] The base material 10 is formed by laminating a plurality of ceramic layers 51, 52. In this example, two ceramic layers are laminated, but the number of ceramic layers to be laminated is not particularly limited. Here, for convenience of explanation, the ceramic layer constituting the first surface 101 of the base material 10 will be referred to as the first ceramic layer 51, and the ceramic layer constituting the second surface 102 of the base material 10 will be referred to as the second ceramic layer 52. Therefore, the above-described substrate region 2 and outer peripheral region 3 are formed in the first and second ceramic layers 51, 52, respectively.

[0022] Each ceramic layer 51, 52 can be formed of a high-temperature fired ceramic mainly composed of, for example, alumina (Al2O3).

[0023] Also, via holes (not shown) are formed between the respective ceramic layers 51, 52, and the conductive patterns formed on the first surface 101 and the second surface 102 are electrically connected by vias filled in the via holes as will be described later.

[0024] <1-2. Substrate region> As shown in FIG. 2, in the substrate region 2 of the first surface 101, a plurality of substrate elements 21 that are divided into individual ceramic substrates are arranged side by side vertically and horizontally. Each substrate element 21 is formed in a rectangular shape, and internal circuit elements are formed by conductive patterns for products made of various metal layers and the like. In this embodiment, as an example, four conductive patterns 21a to 21d for products are formed, but the form of the pattern is not limited to this.

[0025] As shown in FIG. 3, the conductive patterns 21a to 21d for products are covered by a metal plating layer 22. The metal plating layer 22 is connected to other components via a bonding material such as a brazing material or solder. That is, the metal plating layer 22 serves as a joint portion with other components. The conductive patterns 21a to 21d for products are formed of a conductive metal material. Examples of such a metal material include tungsten (W), molybdenum (Mo), copper (Cu), and silver (Ag). On the other hand, the metal plating layer 22 can be formed by nickel (Ni) plating, gold (Au) plating, or the like. Note that the metal plating layer 22 may be formed of a plurality of layers. For example, it may be composed of Ni plating formed on the conductive patterns 21a to 21d for products and an Au plating coating formed on the Ni plating coating.

[0026] Each substrate element 21 has a rectangular shape such as a rectangle or a square, and the length of one side thereof is about 0.1 to 1.0 mm after firing. In the substrate region 2, on the surface of the base material 10, division grooves 18 extending vertically and horizontally are formed between adjacent substrate elements 21 to individually partition the substrate elements 21. Thereby, the process of individually dividing the multi-piece ceramic substrate 1 can be easily carried out. Such division grooves 18 are also formed at the boundary between the substrate region 2 and the outer peripheral region 3. Note that the division grooves 18 may be formed only on one of the surfaces of the base material 10.

[0027] As shown in FIG. 3, in the substrate region 2 of the second surface 102 as well, similar to the first surface 101, a plurality of substrate elements 21 that are divided into individual ceramic substrates are arranged side by side vertically and horizontally. The substrate elements 21 on the first surface 101 and the substrate elements 21 on the second surface 102 are formed at the same positions on the respective surfaces 101 and 102. Therefore, when the multi-piece ceramic substrate 1 is divided along the above-described dividing grooves 18, substrate elements 21 having product conductive patterns and metal plating layers are formed on both surfaces of each ceramic substrate 1. However, generally, the product conductive pattern 25 of the substrate element 21 on the second surface 102 is different from the product conductive patterns 21a to 21d of the substrate element 21 on the first surface 101.

[0028] <1-3. Outer Peripheral Region> The outer peripheral region 3 constitutes the outer peripheral portion of the base material 10. Since the outer peripheral region 3 does not become the substrate element 21 of the multi-piece ceramic substrate 1 and is discarded after firing, no internal circuit elements are formed in the outer peripheral region 3. However, dummy conductive patterns are formed in the outer peripheral region 3 to suppress deformation such as warping of the substrate 1 that may occur during the firing process.

[0029] As shown in FIG. 2, a plurality of dummy conductive patterns 31 formed in a rectangular shape are arranged side by side vertically and horizontally in the outer peripheral region 3. In the present embodiment, as an example, three rows of dummy conductive patterns 31 are formed in the width direction from the outer edge of the base material 10 toward the substrate region 2. Further, these dummy conductive patterns 31 are formed on four sides of the base material 10 other than the four corners, and are formed symmetrically on each of the two pairs of opposing sides of the base material 10. When applying the metal plating layer 22 by the electrolytic plating method, for example, for the purpose of adjusting the plating thickness within the substrate region 2, dummy conductive patterns 31 painted solid may be formed at the four corners of the outer peripheral region 3. Therefore, depending on the purpose, the dummy conductive patterns 31 at the four corners may or may not be formed, but may not be formed as shown in FIG. 2. Further, by forming the dummy conductive patterns 31 symmetrically on each of the two pairs of opposing sides of the base material 10, the occurrence of each warping can be suppressed uniformly.

[0030] As shown in FIG. 3, a dummy conductive pattern 31 similar to that of the first surface 101 is also formed in the outer peripheral region 3 of the second surface 102. The dummy conductive pattern 31 on the second surface 102 is the same size as and is formed at the same position as the dummy conductive pattern 31 on the first surface 101. Therefore, when the second surface 102 is seen through from the first surface 101 side, the dummy conductive pattern 31 on the first surface 101 coincides with the dummy conductive pattern on the second surface 102. However, the dummy conductive pattern 31 on the first surface 101 and the dummy conductive pattern on the second surface 102 do not necessarily have to completely coincide, and may be slightly offset.

[0031] Each dummy conductive pattern 31 has a rectangular shape such as a rectangle or a square, and the width of one side thereof may be 0.1 to 5.0 mm after firing, preferably about 0.1 to 1.0 mm, and more preferably about 0.4 to 0.5 mm. The length of the gap between adjacent dummy conductive patterns can be, for example, about 0.05 to 0.10 mm. Further, the length of one side of the dummy conductive pattern 31 is preferably 0.5 to 8.0% of the length of the short side of the base material 10. The length of the gap between adjacent dummy conductive patterns 31 is preferably 0.1 to 0.3% of the length of the short side of the base material 10. Within such a range, as will be described later, the difference in the thickness of the dummy conductive pattern 31 can be reduced, and as a result, the amount of undulation after firing can be reduced.

[0032] Note that the size of each dummy conductive pattern 31 does not necessarily have to be the same as that of the substrate element 21 in the substrate region 2. Therefore, for example, the gap between adjacent dummy conductive patterns 31 may not be on the line extending the dividing groove 18 in the substrate region 2. Further, the dummy conductive pattern 31 is not coated with the metal plating layer 22.

[0033] In addition, notch 36 for aligning the substrate 1 is provided in the outer peripheral region 3 of the base material 10. These notches 36 are used as alignment marks (indicators) when stacking the respective ceramic layers or cutting the substrate 1 during the manufacture of the substrate 1, but their positions, sizes, and numbers are not particularly limited. In addition, electrodes can be attached when applying the metal plating layer 22. Instead of the notches 36, or in addition to the notches 36, through holes can also be formed.

[0034] <2. Manufacturing method of multi-piece ceramic substrate> Next, the manufacturing method of the multi-piece ceramic substrate 1 will be described.

[0035] The multi-piece ceramic substrate 1 is manufactured by the following steps. (1) Conductor pattern forming step (2) Laminating step (3) Dividing groove forming step (4) Firing step (5) Plating step

[0036] <2-1. Conductor pattern forming step> Prepare the first ceramic layer 51G and the second ceramic layer 52G. These ceramic layers 51G, 52G are ceramic green sheets formed, for example, by kneading a raw material powder mainly composed of a powder of a ceramic component together with a suitable organic solvent and a binder to prepare a slurry, and forming this slurry into a sheet shape by a forming method such as the doctor blade method or the lip coater method. These ceramic layers 51G, 52G are sintered in a subsequent firing step to become the ceramic layers 51, 52 constituting the base material 10.

[0037] Next, through-holes are formed at predetermined positions of each ceramic layer 51G and 52G using a laser or the like. These through-holes are filled with a metal paste containing metal powder. This metal paste becomes a via conductor after sintering. Next, a product conductive pattern 21G and a dummy conductive pattern 31G are formed on one surface of each ceramic layer 51G and 52G. The product conductive pattern 21G and the dummy conductive pattern 31G are made of a metal paste and become the product conductive pattern 21 and the dummy conductive pattern 31 after firing. These are formed using the screen printing method. Thereby, product conductive patterns 21aG to 21dG constituting circuit elements, wirings, etc. are printed and formed in the substrate region 2. Also, a dummy conductive pattern 31G is formed in the outer peripheral region 3. After firing, the product conductive patterns 21a to 21d of each ceramic layer 51 and 52 may be electrically connected via via conductors (not shown). On the other hand, the dummy conductive pattern 31 and the dummy conductive layer 32 are not connected to the product conductive patterns 21a to 21d.

[0038] <2-2. Laminating Process> The two ceramic layers 51G and 52G on which the metal paste has been printed as described above are laminated. Specifically, in each ceramic layer 51G and 52G, they are laminated and pressure-bonded so that the surface on which the conductor patterns 21aG to 21dG are formed becomes the surface of the flat laminate. Thereby, a flat laminate having a thickness of, for example, about 0.15 to 1.0 mm is obtained.

[0039] <2-3. Dividing Groove Forming Process> In order to form the dividing groove 18 described above, the dividing groove 18 is formed on the surface of the flat laminate along the boundaries of each substrate element 21 in the substrate region 2 and the boundary between the substrate region 2 and the outer peripheral region 3 using a laser, a cutter, or the like. At this time, the dividing groove 18 may be formed on at least one surface of the flat laminate corresponding to the first surface 101 and the second surface 102 of the base material 10.

[0040] <2-4. Firing Process> The flat laminate is fired. For example, firing is performed at 1300 to 1700 °C for 20 to 40 hours. Thereby, the base material 10 composed of the ceramic layers 51 and 52 is obtained.

[0041] <2-5. Plating Process> In the plating process, metal plating is applied to the product conductive patterns 21a to 21d on the first surface 101 of the base material 10. The plating treatment can be carried out using a conventionally known method such as electrolytic plating. Thus, the multi-piece ceramic substrate 1 described above is completed.

[0042] Subsequently, when manufacturing individual ceramic substrates from the multi-piece ceramic substrate 1, the base material 10 is divided at the boundary between the substrate region 2 and the outer peripheral region 3, and the outer peripheral region 3 is discarded. Further, if the substrate region 2 is divided into individual substrate elements 21, individual ceramic substrates can be obtained.

[0043] <3. Features> According to the multi-piece ceramic substrate 1 formed as described above, the following effects can be obtained.

[0044] (1) Since the dummy conductive pattern 31 is provided in the outer peripheral region 3, it is possible to suppress the warping of the multi-piece ceramic substrate 1 that may occur during sintering. In particular, since a plurality of dummy conductive patterns 31 are arranged in the outer peripheral region 3, it is possible to suppress the variation in the thickness of the dummy conductive pattern 31 in the outer peripheral region 3. For example, if a solid conductive pattern is formed in the outer peripheral region 3, thickness variation is likely to occur during printing. Due to the characteristics of the screen printing method, such thickness variation becomes more prominent as the printing area is larger. Specifically, as shown in FIG. 4, in the width direction from the outer edge of the multi-piece ceramic substrate 1 toward the substrate region 2, the thickness of the conductive pattern is larger at the outer edge of the multi-piece ceramic substrate 1 and at the portion adjacent to the substrate region 2, and the thickness of the conductive pattern is smaller near the center of both. If such a large variation in thickness occurs, there is a risk of warping in the outer peripheral region 3 after firing.

[0045] On the other hand, as in this embodiment, when the dummy conductive pattern formed in the outer peripheral region 3 is composed of a set of patterns with small sizes and their total area is made to be approximately equal to that of solid coating, the printing area of each pattern can be reduced. Therefore, as shown in FIG. 5, since the variation in thickness at each dummy conductive pattern 31 is suppressed, the variation in thickness can be suppressed for the entire dummy conductive pattern 31 formed in the outer peripheral region 3. As a result, it is possible to suppress the occurrence of undulation in the outer peripheral region 3 after firing. For example, it is possible to prevent stress from concentrating during the handling of a multi-piece ceramic substrate 1 and prevent the multi-piece ceramic substrate from cracking.

[0046] (2) On the first surface 101 and the second surface 102 of the base material 10, since the dummy conductive patterns 31 are formed in the same shape and at the same position, the shrinkage during sintering can be made uniform. Therefore, it is possible to suppress the occurrence of undulation in the outer peripheral region 3 after firing.

[0047] (3) Since the above-described effects can be obtained even if the size of each dummy conductive pattern 21 is not the same as that of the substrate element 21 in the substrate region 2, the degree of freedom in the design (size, position, etc.) of each dummy conductive pattern 21 can be increased.

[0048] <4. Modification Example> As described above, an embodiment of the present invention has been explained, but the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist thereof. Hereinafter, modification examples of the present invention will be explained. However, the following modification examples can be combined as appropriate.

[0049] (1) In the above embodiment, the dummy conductive pattern 31 is formed in a rectangular shape, but it is not limited thereto, and various shapes can be used. For example, it can be circular, polygonal, or the like. However, a rectangular shape is preferable because the dummy conductive pattern 31 can be provided without extra gaps within the same area.

[0050] In the above embodiment, the shapes of the substrate element 21 and the dummy conductive pattern 31 are different, but they may be the same.

[0051] (2) In the above embodiment, the dummy conductive pattern 31 is formed not on the entire circumference of the outer peripheral region 3 but on a part of it, but it can also be formed on the entire circumference. When forming on a part, for example, it is preferably formed on 70% or more of the circumferential direction of the outer peripheral region 3. Further, when forming the dummy conductive pattern 31 on a part of the outer peripheral region 3, other dummy conductive layers can be appropriately formed in the region where the dummy conductive pattern 31 is not formed. Also, a metal plating layer can be formed as needed.

[0052] (3) FIG. 6 is a plan view of the multi-piece ceramic substrate 1 according to another embodiment of the present invention. This substrate, in addition to the dummy conductive pattern 31 in the region 3 shown in the above embodiment, Periphery a plurality of dummy conductive patterns 39 extending crosswise from the center of the base material 10 Periphery toward the region 3 are provided. As a result, one multi-piece ceramic substrate 1 includes four substrate regions 2. That is, a plurality of dummy conductive patterns 31, 39 are provided so as to surround the four substrate regions 2. FIG. 6 shows an example having four substrate regions 2, but the number of substrate regions 2 is not limited to this. That is, by forming a plurality of dummy conductive patterns 39 inside the base material 10, a plurality of substrate regions 2 surrounded by these plurality of dummy conductive patterns 31, 39 can be formed.

Example

[0053] Hereinafter, examples of the present invention will be described. However, the present invention is not limited to the following examples.

[0054] <1. Preparation of Examples and Comparative Examples> As follows, multiple pick-up ceramic substrates according to Example 1, Example 2, and the Comparative Example were produced one by one by the manufacturing method described above. FIG. 7 is a schematic plan view of Example 1, Example 2, and the Comparative Example. In Example 1 and Example 2, a plurality of dummy conductive patterns are formed over the entire outer peripheral region. On the other hand, in the Comparative Example, a coated conductive layer is formed over the entire outer peripheral region. Details are as follows. (1) Dimensions of the base material: 48×75 mm (38×60 mm after firing) (2) Dimensions of the substrate region: 30×50 mm (20×40 mm after firing) (3) Dimensions of the substrate elements in the substrate region: 1.0×0.8 mm (0.8×0.6 mm after firing) (4) Width of the outer peripheral region (length in the direction from the outer edge of the base material toward the substrate region): 10 mm (5 mm after firing) (5) Thickness of the base material: 0.1 mm (0.1 mm after firing) (6) Material of the base material: Alumina (7) Materials of the conductive pattern for products and the dummy conductive pattern: Tungsten and molybdenum (8) Materials of the metal plating layer: Ni, Au

[0055] Regarding other dimensions, they are as shown in Table 1. (The numerical values are those after firing.) Note that the dimensions of the dummy conductive pattern in Table 1 refer to the dimensions of each finely divided dummy conductive pattern. For the Comparative Example, since a coated conductive pattern as shown in FIG. 4 is formed over the entire outer peripheral region, the dimensions of the dummy conductive pattern and the dimensions of the gaps between the dummy conductive patterns in Table 1 are not described. As a result of the inventor's intensive repeated studies, if the ratio of the width of the dummy conductive pattern in the direction parallel to any one side of the fired base material to the length of that side is 0.5 to 8%, and the ratio of the length of the gap between adjacent dummy conductive patterns in the direction parallel to any one side of the fired base material to the length of that side is in the range of 0.1 to 0.3%, as will be described later, the maximum value of the warp amount of the substrate could be suppressed to 0.7 mm or less.

Table 1

[0056] <2. Evaluation of the Thickness of the Dummy Conductive Pattern in the Outer Peripheral Region> In a multi-piece ceramic substrate before firing, the thickness of the metal paste after screen printing of the dummy conductive pattern was measured in the outer peripheral region of the long side of the substrate. The results are as shown in Table 2 below. (The ends (outer edge side of the substrate), the center, and the ends (substrate region side) in Table 2 correspond to the positional relationships shown in FIGS. 4 and 5.) Note that the following dimensions are the average values of 8 substrates.

Table 2

[0057] In the comparative example, since the dummy conductive layer is formed by printing across the entire width direction of the outer peripheral region, as shown in FIG. 4 described above, the thickness near the center is smaller than the thickness near the ends, and according to the actual measurement (Table 2), it is about 55%. On the other hand, in Examples 1 and 2, since a plurality of dummy conductive patterns are formed by printing in the outer peripheral region, as shown in FIG. 5 described above, the variation in thickness is smaller. Specifically, as shown in Table 2, the thickness near the center is about 75% of the thickness near the ends in Example 1 and about 100% in Example 2. Therefore, it was found that the smaller the dummy conductive pattern, the smaller the variation in thickness.

[0058] <3. Evaluation of the Undulation in the Outer Peripheral Region> Three multi-piece ceramic substrates according to Examples 1 and 2 and Comparative Example (No. #1 to #3) were measured for the surface shape of the outer peripheral region on the long side as the change in surface height. This measurement was performed using a surface roughness meter that operates by bringing a probe into contact with the surface. The results are as shown in FIGS. 8 to 10. The horizontal axis of the graphs in these figures indicates the long side (total length 60 mm) of the multi-piece ceramic substrate, and the vertical axis indicates the height (mm) of the multi-piece ceramic substrate. Although the curves in FIGS. 8 to 10 are partially interrupted, this is because the height measurement could not be performed due to the presence of the notch 36. As shown as an example in FIG. 10, on the surface of the outer peripheral region, the portion where the difference in height between adjacent unevenness is the largest was measured as the "maximum value of the undulation amount". The "maximum value of the undulation amount" for each sheet is as shown in Table 3. [Table 3]

[0059] As shown in FIGS. 8 to 10, the "maximum value of the undulation amount" of the Comparative Example was the largest, and the "maximum value of the undulation amount" of Example 2 was the smallest. This is considered to be due to the variation in the thickness of the outer peripheral region. As a result of the study by the present inventor, it was found that when the "maximum value of the undulation amount" exceeds 0.7 mm, there is a high risk that stress will concentrate during handling of the multi-piece ceramic substrate and the multi-piece ceramic substrate will crack.

Explanation of Signs

[0060] 1 Multi-piece ceramic substrate 10 Base material 2 Substrate region 21 Substrate element 21a to 21d Conductive patterns for products 3 Outer peripheral region 31 Conductive pattern for dummy

Claims

1. A rectangular substrate having a first surface and a second surface, formed by laminating a plurality of ceramic layers, wherein each of the first surface and the second surface has a substrate region and an outer peripheral region formed outside the substrate region, and a substrate; A plurality of substrate elements formed on at least a part of each of the substrate regions and having conductive patterns for products coated with a metal plating layer; A plurality of dummy conductive patterns formed on at least a part of each of the outer peripheral regions and arranged at a predetermined interval; Comprising: A multi-piece ceramic substrate in which, when the second surface is seen through from the first surface side of the substrate, the dummy conductive patterns on the first surface coincide with the dummy conductive patterns on the second surface.

2. The multi-piece ceramic substrate according to claim 1, wherein each of the plurality of dummy conductive patterns is formed in a rectangular shape.

3. The multi-piece ceramic substrate according to claim 1 or 2, wherein the plurality of dummy conductive patterns are formed in a plurality of rows in a direction from the outer peripheral region toward the substrate region and are formed in a plurality of rows in the circumferential direction of the outer peripheral region.

4. The multi-piece ceramic substrate according to any one of claims 1 to 3, wherein the thickness of the dummy conductive pattern having the smallest thickness among the plurality of dummy conductive patterns is 75% or more of the thickness of the dummy conductive pattern having the largest thickness.

5. The multi-piece ceramic substrate according to any one of claims 1 to 4, wherein the plurality of dummy conductive patterns are formed in 70% or more of the circumferential direction of the outer peripheral region.

6. The multi-piece ceramic substrate according to any one of claims 1 to 5, wherein the plurality of dummy conductive patterns are formed symmetrically on each of two pairs of opposite sides of the substrate.

7. The multi-piece ceramic substrate according to any one of claims 1 to 6, wherein no dummy conductive pattern is formed at four corners of the substrate in the outer peripheral region.

8. The ratio of the width of the dummy conductive pattern in a direction parallel to one side of the substrate to the length of any one side of the substrate is 0.5 to 8%, and The ratio of the predetermined interval of the dummy conductive pattern in a direction parallel to one side of the substrate to the length of any one side of the substrate is 0.1 to 0.3%. The multi-piece ceramic substrate according to any one of claims 1 to 7.

9. Preparing a plurality of ceramic layers including a first ceramic layer and a second ceramic layer, wherein one surface of the first ceramic layer and the second ceramic layer respectively has a substrate region having a plurality of substrate elements and an outer peripheral region formed outside the substrate region; Printing a product conductive pattern on each of the substrate elements on at least a part of each of the substrate regions of the first ceramic layer and the second ceramic layer; Printing a plurality of dummy conductive patterns arranged at a predetermined interval on at least a part of each of the outer peripheral regions of the first ceramic layer and the second ceramic layer; Stacking the plurality of ceramic layers so that one surface of the first ceramic layer and one surface of the second ceramic layer become a first surface and a second surface respectively to form a base material; Forming dividing grooves along the boundaries of the respective substrate elements in the substrate region and the boundary between the substrate region and the outer peripheral region on at least one of the first surface or the second surface; Firing the base material; Forming a metal plating layer so as to cover the product conductive pattern; and A method for manufacturing a multi-piece ceramic substrate, wherein when the second surface is seen through from the first surface side of the base material, the dummy conductive pattern on the first surface coincides with the dummy conductive pattern on the second surface.

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