Substrate and electronic component module

Abstract

Provided are a substrate and an electronic component module in which barrier properties and substrate strength are further improved. A substrate 1a, 1b according to the present disclosure comprises: a metal plate material 10; a pair of internal conductors 30 that are provided inside the metal plate material 10 and extend from the inside of the metal plate material 10 to the obverse surface and reverse surface thereof; an external electrode 40 that is electrically connected to each of the pair of internal conductors 30; and a ceramic 20 that electrically insulates the metal plate material 10 and the internal conductors 30 and covers at least part of the metal plate material 10. The metal plate material 10 extends between the pair of internal conductors 30 in a direction intersecting the thickness direction of the metal plate material 10, the metal plate material 10 extends between the pair of internal conductors 30, and the metal plate material 10 is not used as electrical wiring.

Description

Substrate and Electronic Component Module

[0001] The present disclosure relates to a substrate and an electronic component module.

[0002] Patent Document 1 discloses a sealed case that accommodates a battery stack. The sealed case is composed of a case body and a lid body. The case body includes a penetration portion provided penetrating the bottom portion, an external terminal portion formed in a thin film shape along the bottom surface of the case body, and a holding portion formed protruding from the penetration portion into the internal space of the sealed case, respectively. Further, it is disclosed that the case body described in Patent Document 1 is formed using a ceramic material.

[0003] Japanese Patent Application Laid-Open No. 2010-118159

[0004] In the sealed case that accommodates the battery stack disclosed in Patent Document 1, from the viewpoint of achieving electrical insulation with the battery stack, it is preferable that the case body is formed using an insulating ceramic material.

[0005] However, compared with metals, ceramic materials have lower toughness and are more brittle, so cracks are prone to occur. Therefore, there has been a risk that barrier properties may decrease, for example, water vapor, moisture or the like may enter through the cracks.

[0006] In view of the foregoing, an object of the present disclosure is to provide a substrate and an electronic component module in which barrier properties and substrate strength are further improved.

[0007] The substrate of the present disclosure is a substrate comprising: a metal plate; a pair of internal conductors provided inside the metal plate and extending from the inside of the metal plate to the front surface and the back surface; external electrodes each electrically connected to the pair of internal conductors; and a ceramic that electrically insulates the metal plate from the internal conductors and covers at least a part of the metal plate, wherein the metal plate extends between the pair of internal conductors in a direction intersecting the thickness direction of the metal plate, and the metal plate is not used as an electrical wiring.

[0008] The electronic component module of the present disclosure includes the above-described substrate and an electronic component mounted on the substrate.

[0009] According to the substrate and electronic component module of this disclosure, the ceramic electrically insulates the metal plate material from the internal conductors and covers at least a portion of the metal plate material, and the metal plate material extends between a pair of internal conductors. Therefore, even if a crack occurs in the ceramic, the metal plate material can prevent the crack from penetrating the substrate, thereby improving the barrier properties against water vapor and other elements. Furthermore, the strength of the substrate can be further improved by the ceramic and metal plate material.

[0010] Figure 1 is a schematic cross-sectional view of the substrate of the first embodiment. Figure 2 is a schematic plan view of the substrate of the first embodiment. Figure 3 is a schematic cross-sectional view of the manufacturing process of the substrate of the second embodiment. Figure 4 is a schematic cross-sectional view of the manufacturing process of the substrate of the second embodiment. Figure 5 is a schematic cross-sectional view of the manufacturing process of the substrate of the second embodiment. Figure 6 is a schematic cross-sectional view of the manufacturing process of the substrate of the second embodiment. Figure 7 is a schematic cross-sectional view of the substrate of the second embodiment. Figure 8 is a schematic cross-sectional view of the electronic component module of the present disclosure. Figure 9 is a schematic cross-sectional view of a modified example of the electronic component module of the present disclosure. Figure 10 is a table showing the results of a demonstration test related to the substrate of the present disclosure.

[0011] The “substrate” and “electronic component module” of this disclosure will be described in detail below. While drawings will be referenced as necessary, the illustrations are provided for illustrative purposes only to aid in understanding this disclosure, and their appearance and dimensional ratios may differ from those of the actual products.

[0012] In this specification, "plan view" refers to the form of an object viewed from above or below along the thickness direction based on the substrate or electronic component module. Furthermore, "cross-sectional view" refers to the form of an object viewed from a direction substantially perpendicular to the thickness direction based on the substrate or electronic component module (simply put, the form when cut by a plane parallel to the thickness direction). In this specification, "up / down direction" and "left / right direction" as used directly or indirectly correspond to the up / down direction and left / right direction in the figures, respectively. Unless otherwise specified, the same reference numeral or symbol indicates the same member / part or has the same meaning. In a preferred embodiment, the vertical downward direction (i.e., the direction in which gravity acts) can be considered as the "downward direction," and the opposite direction as the "upward direction."

[0013] <<Substrate of the First Embodiment>> The substrate 1a of the first embodiment of this disclosure comprises a metal plate material 10, a ceramic 20, an internal conductor 30, and an external electrode 40 (see Figure 1). Hereinafter, each component will be described in detail with reference to the drawings.

[0014] The metal plate material 10 is a plate-shaped member having a front surface and a back surface, and is sized to support the electronic component ED (see Figure 8). Although this is merely an example, the thickness D1 of the metal plate material 10 may be 10 μm or more and 1000 μm or less, for example, 200 μm or less.

[0015] The metal sheet material 10 may be selected from the group consisting of copper, copper alloys, nickel, nickel alloys, aluminum, aluminum alloys, carbon steel, stainless steel, alloy tool steel, machine structural alloy steel, high-tensile steel, and cemented carbide. "Copper alloy" refers to an alloy in which copper is the main component and other metal elements are added (e.g., brass, bronze, cupronickel, beryllium copper, lead brass, lead bronze). "Nickel alloy" refers to an alloy in which nickel is the main component and other metal elements (e.g., iron, chromium, molybdenum, cobalt, etc.) are added. "Aluminum alloy" refers to an alloy in which aluminum is the main component and other metal elements (e.g., copper, magnesium, silicon, zinc, etc.) are added. "Carbon steel" refers to iron-based steel in which carbon is the main alloying element. "Stainless steel" refers to an alloy of iron and chromium, and may also contain nickel, carbon, etc. "Alloy tool steel" refers to steel to which alloying elements such as chromium, tungsten, molybdenum, and vanadium have been added to the carbon steel mentioned above. "Alloy steel for machine structures" refers to steel to which alloying elements such as chromium, nickel, molybdenum, and manganese have been added to carbon steel. "High-tensile steel" refers to steel with a tensile strength of 490 MPa or higher. "Cemented carbide" refers to alloys in which carbides of metals from groups IVa, Va, and VIa of the periodic table are sintered with iron-based metals such as iron, cobalt, and nickel. All of the above metal materials can prevent cracks from penetrating the substrate even if cracks occur in the ceramic, thus improving the strength of the substrate.

[0016] The metal plate material 10 is not used as electrical wiring. In this specification, "not used as electrical wiring" means that it is not used for supplying power or transmitting electrical signals. Therefore, it is possible to prevent heat generation in the metal plate material 10 due to the flow of electric current, thereby further improving the strength of the substrate.

[0017] The ceramic metal plate 10 may be covered with insulating ceramic 20 to provide insulation from the internal conductor 30 and external electrodes 40, which will be described later. As an example of how the ceramic 20 covers the metal plate 10, in the substrate 1a of the first embodiment shown in Figures 1 and 2, the ceramic 20 covers the front and back surfaces of the metal plate 10 and the inner surfaces of the through holes in the metal plate 10. By using such a covering method, insulation can be provided between the metal plate 10 and the internal conductor 30 and external electrodes 40. Note that the covering method of the ceramic 20 is not limited to the method shown in Figure 1, and any covering method that provides electrical insulation between the internal conductor 30 and external electrodes 40 and the metal plate 10 is acceptable. For example, instead of the covering method shown in Figure 1, the region between the external electrodes 40 in a direction intersecting the thickness direction of the metal plate 10, and the region from each external electrode 40 to the outer edge of the metal plate 10, may have the front and / or back surfaces of the metal plate 10 exposed from the ceramic 20.

[0018] The ceramic 20 can be any ceramic material as long as it has insulating properties. Examples of ceramic 20 include LTCC (Low Temperature Co-fired Ceramics) or HTCC (High Temperature Co-fired Ceramics). LTCC refers to a material made by adding a glass-based material to aluminum oxide that can be fired at a lower temperature (below 1000°C) than conventional ceramics. HTCC refers to a material mainly composed of aluminum oxide or aluminum nitride that can be fired at a high temperature of 1500°C or higher.

[0019] An internal conductor 30 is provided inside the metal plate material 10 (inside the through hole). The internal conductor 30 is provided to electrically connect the external electrode 40 on the surface side and the external electrode 40 on the back side of the metal plate material 10. Therefore, the internal conductor 30 may extend from the inside of the metal plate material 10 to the surface and back. Note that the internal conductor 30 does not need to extend in a straight line as shown in Figure 1, but may extend to the surface and back while bending.

[0020] The internal conductor 30 is preferably made of copper, considering the heat dissipation properties of the substrate 1a and the contact properties with the external electrodes 40 described later. However, the internal conductor 30 may be made of a material other than copper that has good heat dissipation properties or a material that has good contact properties with the external electrodes 40.

[0021] - External electrodes The external electrodes 40 are electrically connected to the internal conductor 30. More specifically, they may be provided on the ceramic 20 that insulates the metal plate material 10 from the front and back surfaces of the metal plate material 10. The external electrodes 40 may have two electrodes on the front surface and two electrodes on the back surface corresponding to the front surface electrodes. These electrodes may correspond to, for example, the input terminal, the output terminal, or the anode or cathode. For example, the external electrodes 40 on the front surface are electrically connected to an electronic component mounted on the substrate 1a, and the external electrodes 40 on the back surface are electrically connected to an external circuit board. Although the external electrodes 40 are shown as rectangular in the plan view in Figure 2, they are not limited to this shape.

[0022] Copper may be used as an example of an external electrode. Generally, copper is known to be a metal material with good conductivity, good heat dissipation, quickly diffusing heat so that the electrode does not easily become hot, and readily alloys with tin during soldering, resulting in good contact with solder. Therefore, by using copper for the external electrode 40 in the substrate 1a of this embodiment, good conductivity and heat dissipation can be achieved while also improving adhesion between the substrate 1a and the electronic component ED, and between the substrate and the external circuit board.

[0023] In the first embodiment, the substrate 1a having the above components is configured such that the metal plate material 10 extends between the pair of internal conductors 30. When electrically connecting the substrate 1a and the electronic component ED in this embodiment, stress on the substrate 1a tends to be applied near the center in a direction intersecting the thickness direction of the substrate 1a (the region between the pair of external electrodes 40). Therefore, in the prior art (a structure that holds electronic components in a case made only of ceramic material), if stress is applied to the region between the external electrodes and a crack occurs that penetrates the ceramic material, there is a possibility that moisture (or water vapor) will enter the electronic component ED through the crack.

[0024] However, in the first embodiment of this model, the substrate 1a has a metal plate 10 extending between a pair of internal conductors 30, which are prone to stress on the substrate 1a. Therefore, even if stress is applied to the ceramic 20 covering the metal plate 10 and cracks occur, the metal plate 10 can prevent cracks from penetrating the substrate 1a, thus further improving the barrier properties against water vapor and the like. Furthermore, the strength of the substrate can be further improved by the ceramic 20 and the metal plate 10.

[0025] In a more specific embodiment of the substrate 1a of this embodiment, when the thickness D1 of the metal plate material 10 is a and the thickness D2 of the ceramic 20 is b, a / b may be 5% or more and 100% or less, and the total thickness of the substrate 1a may be 200 μm or less (see Figure 1). In this specification, the thickness D2 of the ceramic 20 refers to the sum of the thicknesses of the ceramics provided on both sides of the metal plate material 10 (see Figure 1). The technical significance of this numerical range will be explained in detail in the embodiments described later.

[0026] <<Substrate of the Second Embodiment>> Next, the substrate 1b of the second embodiment will be described with reference to Figure 7. In describing the substrate 1b of the second embodiment, configurations common to the substrate 1a of the first embodiment described above will be omitted from the explanation as appropriate.

[0027] In the substrate 1b of the second embodiment, there is an exposed portion 11 outside the pair of external electrodes 40 where the metal plate material 10 is exposed without being covered by the ceramic 20 (see Figure 7). In this specification, "outside the external electrodes 40" refers to a predetermined position in the region from the outer end 40e of the external electrodes 40 to the outer peripheral edge 10e of the metal plate material. When the metal plate material 10 is exposed to the outside at this position, the metal plate material 10 can be bent.

[0028] Here, as shown in Figure 7, by bending the metal plate material 10 at the exposed portion 11 to form a wall portion 10w that surrounds the external electrode 40, a cavity CV for housing the electronic component ED can be formed in the position surrounded by the wall portion 10w. By housing the electronic component ED in the cavity CV, an electronic component module M can be formed on the substrate 1b of this embodiment, with the electronic component ED provided on it.

[0029] In a preferred embodiment of the substrate 1b, as shown in Figure 9, ceramic 20 may be provided on the inner surface of the wall portion 10w. More specifically, ceramic 20 may be provided on the surface of the wall portion 10w facing the electronic component ED housed in the cavity CV. In this embodiment, the electronic component ED is placed in the cavity CV beforehand, and then the cavity CV is sealed. With this configuration, the electronic component ED can be placed in the already formed cavity CV, making subsequent sealing easier and improving airtightness. Furthermore, since ceramic has insulating properties, by providing ceramic 20 at that position, electrical isolation from the electronic component ED can be achieved.

[0030] <<Manufacturing Method of Substrate in the Second Embodiment>> Next, the manufacturing method of the substrate will be described with reference to Figures 3 to 6. While the manufacturing method of the substrate in the second embodiment will be described in detail below, the substrate in the first embodiment can also be manufactured in the same manner.

[0031] First, as shown in Figure 3, a metal plate 10 is prepared, with through holes H1 provided in the positions where the internal conductor 30 will be placed.

[0032] Next, the uncured ceramic sheet ST is attached to the upper and lower surfaces of the prepared metal plate material 10, as shown in Figure 4. This attachment may be performed by heat compression bonding, for example, but is not limited to heat compression bonding.

[0033] Then, in order to arrange the internal conductor 30 inside the metal plate material 10, through holes H2 are formed at the positions where the internal conductor 30 will be formed, as shown in Figure 5. For example, the through holes H2 can be formed using known etching techniques (e.g., wet etching or dry etching), laser processing techniques, or techniques that physically form through holes using drills, etc.

[0034] Then, as shown in Figure 6, metal is embedded in the formed through hole H2. This simultaneously forms the internal conductor 30 and the external electrode 40. Alternatively, instead of forming the internal conductor 30 and the external electrode 40 simultaneously, they may be formed separately.

[0035] Then, as shown in Figure 7, the metal plate 10 is bent at the exposed portion 11 located in the region from the outer end 40e of the external electrode 40 to the outer peripheral edge 10e of the metal plate 10 to form a wall portion 10w that surrounds the external electrode 40. This makes it possible to form a cavity CV for housing the electronic component ED in the position surrounded by the wall portion 10w. Alternatively, the ceramic 20 may be formed on the wall portion 10w before bending the metal plate 10, and then the metal plate 10 may be bent to form a substrate for the electronic component module M as shown in Figure 9.

[0036] Through the above manufacturing process, the substrate 1b of the second embodiment can be manufactured. Furthermore, according to the substrate 1b of the second embodiment, since the metal plate material 10 extends between the pair of internal conductors 30, which are prone to stress on the substrate 1b, even if stress is applied to the ceramic 20 covering the metal plate material 10 and cracks occur, the metal plate material 10 can prevent the cracks from penetrating the substrate 1b. Therefore, the barrier properties against water vapor and the like are further improved. Moreover, the strength of the substrate can be further improved by the ceramic 20 and the metal plate material 10.

[0037] <<Electronic Component Module>> Next, an electronic component module M in which electronic component ED is arranged on the substrate 1b of the second embodiment described above will be explained with reference to Figures 8 and 9. In this explanation, an electronic component module using the substrate 1b of the second embodiment described above will be explained, but the substrate 1a of the first embodiment may also be used.

[0038] As shown in Figures 8 and 9, an electronic component ED is placed on the external electrode 40 on the surface side of the substrate 1b. More specifically, the electronic component ED is placed in a cavity CV partitioned by a wall portion 10w. An example of the electronic component ED may be a solid-state battery or a quartz crystal oscillator. However, the electronic component ED is not limited to a solid-state battery or a quartz crystal oscillator. As described above, the substrate of this embodiment has improved barrier properties against water vapor, etc., so it is possible to suitably place electronic components ED, which are considered to be relatively sensitive to moisture (or water vapor).

[0039] The verification tests concerning the substrates of this disclosure will be described in detail. Specifically, the substrates described in the following examples and comparative examples were manufactured.

[0040] -Substrate of Example 1- In the substrate of the first embodiment shown in Figure 1, the thickness D2 of the ceramic was set to 100 μm, and the thickness D1 of the metal plate was set to 100 μm. As a result, the ratio of the thickness D1 of the metal plate to the thickness D2 of the ceramic was 100% (100 μm / 100 μm (converted to percentage)). In this specification, the measurement of "thickness of the ceramic" is performed by selecting 10 arbitrary points on each of the opposing sides of the ceramic in the vertical direction in a cross-sectional view, measuring the interval between each of these 10 points, and using the average value. The measurement of the thickness of the metal plate is performed in the same manner.

[0041] -Substrate of Example 2- In the substrate of the first embodiment shown in Figure 1, the thickness D2 of the ceramic was set to 125 μm, and the thickness D1 of the metal plate material was set to 75 μm. As a result, the ratio of the thickness D1 of the metal plate material to the thickness D2 of the ceramic was 60% (75 μm / 125 μm (converted to a percentage)).

[0042] -Substrate of Example 3- In the substrate of the first embodiment shown in Figure 1, the thickness D2 of the ceramic was set to 150 μm, and the thickness D1 of the metal plate material was set to 50 μm. As a result, the ratio of the thickness D1 of the metal plate material to the thickness D2 of the ceramic was 33% (50 μm / 150 μm (converted to percentage)).

[0043] —Substrate of Example 4— In the substrate according to the first embodiment shown in Figure 1, the thickness D2 of the ceramic was 175 µm, and the thickness D1 of the metal plate material was 25 µm. As a result, the thickness D1 of the metal plate material / the thickness D2 of the ceramic was 14% (25 µm / 175 µm, converted to percentage notation).

[0044] —Substrate of Example 5— In the substrate according to the first embodiment shown in Figure 1, the thickness D2 of the ceramic was 190 µm, and the thickness D1 of the metal plate material was 10 µm. As a result, the thickness D1 of the metal plate material / the thickness D2 of the ceramic was 5% (10 µm / 190 µm, converted to percentage notation).

[0045] —Substrate of Comparative Example 1— As in the prior art, a ceramic substrate was employed without using a metal plate material. In addition, the thickness of the ceramic substrate was 200 µm.

[0046] In the substrates of Examples 1 to 5 and Comparative Example 1 described above, the presence or absence of cracks penetrating the substrate between the internal conductors 30 was checked. As a checking method, a substrate cross-section check sample was prepared so as to include the position where cracks occurred in the ceramic 20, and the crack occurrence position was observed with a scanning electron microscope (SEM).

[0047] The results of the verification test are shown in Figure 10. According to the results of the verification test, cracks penetrating the ceramic substrate 1b were confirmed in the substrate of Comparative Example 1. On the other hand, in the substrates of Examples 1 to 5, no cracks penetrating the substrate between the internal conductors 30 were observed. Based on this result, the substrate of the present disclosure satisfies that when the thickness of the metal plate material is a and the thickness of the ceramic is b, a / b is 5% or more and 100% or less, and when the total thickness of the substrate is 200 µm or less, cracks penetrating the substrate between the internal conductors 30 can be suitably suppressed.

[0048] It should be noted that the embodiments disclosed herein are illustrative in all aspects and do not serve as a basis for restrictive interpretation. Therefore, the technical scope of the present disclosure is not to be construed only by the above-described embodiments, but is defined based on the description of the claims. In addition, the technical scope of the present disclosure includes all modifications within the meaning and scope equivalent to the claims.

[0049] This disclosure can be suitably used in substrates and electronic component modules that offer improved barrier properties and substrate strength.

[0050] 1, 1a, 1b Substrate 10 Metal plate material 10e Outer edge 10w Wall portion 11 Exposed portion 20 Ceramic 30 Inner conductor 40 Outer electrode 40e Outer end ED Electronic component CV Cavity H1, H2 Through hole ST Ceramic sheet M Electronic component module D1, D2, Thickness

Claims

1. A substrate comprising: a metal plate; a pair of internal conductors provided inside the metal plate and extending from the inside to the front and back surfaces of the metal plate; external electrodes electrically connected to each of the pair of internal conductors; and a ceramic that electrically insulates the metal plate from the internal conductors and covers at least a portion of the metal plate, wherein the metal plate extends between the pair of internal conductors in a direction intersecting the thickness direction of the metal plate, and the metal plate is not used as electrical wiring.

2. The substrate according to claim 1, wherein the metal plate material is selected from at least one of the group consisting of copper, copper alloy, nickel, nickel alloy, aluminum, aluminum alloy, carbon steel, stainless steel, alloy tool steel, machine structural alloy steel, high-tensile steel, and cemented carbide.

3. The substrate according to claim 1 or 2, wherein the ceramic covers the front and back surfaces of the metal plate material.

4. The substrate according to any one of claims 1 to 3, wherein when the thickness of the metal plate material is a and the thickness of the ceramic is b, a / b is 5% or more and 100% or less.

5. The substrate according to claim 4, wherein the total thickness of the substrate is 200 μm.

6. The substrate according to any one of claims 1 to 5, wherein the external electrode is made of copper.

7. The substrate according to any one of claims 1 to 6, wherein the substrate has an exposed portion on the outer side of the pair of external electrodes, in which the metal plate material is exposed without being covered by the ceramic.

8. The substrate according to claim 7, wherein the metal plate material is bent at the exposed portion and has a wall portion that surrounds the position where the external electrode is provided in a plan view.

9. The substrate according to claim 8, wherein a ceramic is provided on the inner surface of the wall portion.

10. An electronic component module comprising a substrate according to any one of claims 1 to 9, and an electronic component mounted on the substrate.

11. An electronic component module comprising a substrate according to claim 8 or 9 and an electronic component mounted on the substrate, wherein the electronic component is arranged in a cavity partitioned by the wall portion.

12. The electronic component module according to claim 10 or 11, wherein the electronic component is a solid-state battery or a quartz crystal oscillator.

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