Joint and joining method

Abstract

To provide a joint and a joining method having high joint strength. [Solution] The bonded body according to the present invention has a first region formed by a first line segment and a second line segment in the cross-section of the bonded layer, where the cross-section of the bonded layer is a plane parallel to the stacking direction of the first and second ceramic substrates, and a first line segment of the bonded interface of the first ceramic substrate that passes through the position closest to the second ceramic substrate in the stacking direction and is perpendicular to the stacking direction in the cross-section is non-interfering with the bonded interface of the second ceramic substrate, and a second line segment of the bonded interface of the second ceramic substrate that passes through the position closest to the first ceramic substrate in the stacking direction and is perpendicular to the stacking direction in the cross-section is non-interfering with the bonded interface of the first ceramic substrate.

Description

Technical Field

[0001] The present invention relates to a joined body and a joining method.

Background Art

[0002] Conventionally, as a technique for joining ceramic substrates to each other to produce a joined body, there has been known a technique of joining ceramic substrates to each other by diffusion bonding that includes polishing joining surfaces, aligning the polished surfaces and pressing the same (see, for example, Patent Document 1).

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] However, in Patent Document 1, although the ceramic substrate is polished by a polishing step such that the surface roughness Ra of the ceramic substrate becomes 0.5 µm, this polishing process damages the substrate surface, which may reduce the strength of the joined body.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide a joined body having high joining strength and a joining method.

Means for Solving the Problem

[0006] To solve the above problems, the bonded body according to the present invention comprises a first ceramic substrate, a second ceramic substrate, and a bonding layer provided between the first and second ceramic substrates for bonding the first and second ceramic substrates, wherein the cross-section of the bonding layer, with the cutting plane being a plane parallel to the stacking direction of the first and second ceramic substrates, has a first region formed by the first line segment and the second line segment, wherein a first line segment of the bonding interface of the first ceramic substrate passes through the position closest to the second ceramic substrate in the stacking direction and is perpendicular to the stacking direction in the cross-section and does not interfere with the bonding interface of the second ceramic substrate, and a second line segment of the bonding interface of the second ceramic substrate passes through the position closest to the first ceramic substrate in the stacking direction and is perpendicular to the stacking direction in the cross-section and does not interfere with the bonding interface of the first ceramic substrate.

[0007] Furthermore, in the bonded body according to the present invention, the surface roughness Ra of the bonding interface between the first and second ceramic substrates is greater than 0.5 μm.

[0008] Furthermore, in the bonded body according to the present invention, the ratio of the sum of the areas of the first region, the second region, and the third region to the sum of the areas of the second region formed by the bonding interface of the first line segment and the first ceramic substrate and the area of ​​the third region formed by the bonding interface of the second line segment and the second ceramic substrate is 3.39 or more and 4.36 or less.

[0009] Furthermore, in the bonded body according to the present invention, the bonding layer is made of an amorphous material.

[0010] Furthermore, the bonding method according to the present invention is a bonding method for bonding ceramic substrates, each having a surface roughness Ra greater than 0.5 μm, comprising a paste application step of applying a bonding paste having a thickness of 18.9 μm to 27.7 μm to the bonding surface of one of the ceramic substrates, and then bringing together the bonding surface of the other ceramic substrate and the glass paste-coated surface of the one ceramic substrate, and heating in a rare gas atmosphere to 850°C to 1050°C, resulting in a bonding strength of 102 kg / m². 2 The method includes a bonding step of joining ceramic substrates together while pressing them with a load.

[0011] Furthermore, in the bonding method according to the present invention, the width of the bonding layer that bonds the ceramic substrates together is 25.7 μm or more and 34.9 μm or less, and when the width of the bonding layer is 34.9 μm, the surface roughness Ra of the bonding surface is 8.7 μm or less.

[0012] Furthermore, in the bonding method according to the present invention, the paste application step involves applying the bonding paste, which is formed using an amorphous material, to the bonding surface of the ceramic substrate.

[0013] Furthermore, in the bonding method according to the present invention, the paste application step involves applying bonding paste to the bonding surface of one ceramic substrate and the bonding surface of the other ceramic substrate, and the bonding step involves joining the ceramic substrates by bringing the bonding paste-coated surfaces together. [Effects of the Invention]

[0014] According to the present invention, a bonded body can be obtained in which ceramic substrates are joined together, and which has high bonding strength. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a schematic cross-sectional view showing the configuration of a joint according to one embodiment of the present invention. [Figure 2] Figure 2 is an enlarged view of region R in Figure 1. [Figure 3] FIG. 3 is a diagram for explaining a bonding layer in a bonded body according to an embodiment of the present invention. [Figure 4] FIG. 4 is a diagram (Part 1) for explaining a method for bonding ceramic substrates according to an embodiment of the present invention. [Figure 5] FIG. 5 is a diagram (Part 2) for explaining a method for bonding ceramic substrates according to an embodiment of the present invention. [Figure 6] FIG. 6 is a diagram (Part 3) for explaining a method for bonding ceramic substrates according to an embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing an SEM image of the bonded body according to Example 1. [Figure 8] FIG. 8 is a diagram showing an SEM image of the bonded body according to Example 2. [Figure 9] FIG. 9 is a diagram showing an SEM image of the bonded body according to Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following description. Various changes or improvements can be added to the present embodiment, and forms with such changes or improvements can also be included in the present invention.

[0017] Embodiment Bonded Body A bonded body and a bonding method according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing the configuration of the bonded body according to an embodiment of the present invention. The bonded body 1 according to the present embodiment includes a first ceramic substrate 11, a second ceramic substrate 12, and a bonding layer 13 provided between the first ceramic substrate 11 and the second ceramic substrate 12 for bonding the first ceramic substrate 11 and the second ceramic substrate 12. In the following description, the vertical direction in FIG. 1 is referred to as the "laminating direction" of the substrates. Further, the length (thickness) of a layer in this laminating direction is referred to as "layer width".

[0018] The first ceramic substrate 11 and the second ceramic substrate 12 are formed using materials such as alumina, aluminum nitride, and beryllium oxide.

[0019] The bonding layer 13 is formed from an amorphous material such as glass, or from metal or ceramic.

[0020] Figure 2 is an enlarged view of region R in Figure 1. The bonded body 1 has a first region R1 formed by a first line segment L1 and a second line segment L2 in the cross-section of the bonding layer 13, which has a cutting surface parallel to the stacking direction of the first ceramic substrate 11 and the second ceramic substrate 12. The first line segment L1 passes through the position of the bonding interface of the first ceramic substrate 11 that is closest to the second ceramic substrate 12 in the stacking direction and is perpendicular to the stacking direction in the cross-section, and does not interfere with the bonding interface of the second ceramic substrate 12. The second line segment L2 passes through the position of the bonding interface of the second ceramic substrate 12 that is closest to the first ceramic substrate 11 in the stacking direction and is perpendicular to the stacking direction in the cross-section, and does not interfere with the bonding interface of the first ceramic substrate 11.

[0021] Figure 3 is a diagram illustrating a bonding layer in a bonded body according to one embodiment of the present invention. The sum (S1+S2+S3) of the area S1 of the first region R1, the area S2 of the second region formed by the bonding interface of the first line segment L1 and the first ceramic substrate 11, and the area S3 of the third region formed by the bonding interface of the second line segment L2 and the second ceramic substrate 12 is greater than the sum (S2+S3) of the area S2 of the second region and the area S3 of the third region. Note that the second and third regions are sets of scattered regions that are independent of each other, depending on the shape of the bonding interface. Because the sum (S1+S2+S3) is greater than the sum (S2+S3), the occupancy rate of the first region R1 in the bonding layer 13 increases, and the bonding strength can be increased.

[0022] In the joined body 1, by satisfying the above relationship, the thickness of the joining layer 13 is suppressed while the region of the first region R1 is secured, thereby making the joined state even stronger.

[0023] [Joining method] Next, the method for joining the first ceramic substrate 11 and the second ceramic substrate 12 in the bonded body 1 will be described with reference to Figures 4 to 6. Figures 4 to 6 are diagrams illustrating a method for joining ceramic substrates according to one embodiment of the present invention. Here, the surface roughness Ra of the bonding surfaces P1 and P2 of the first ceramic substrate 11 and the second ceramic substrate 12 is greater than 0.5 μm, respectively (see Figure 4). For example, the first ceramic substrate 11 and the second ceramic substrate 12 can be used in their as-shipped state without polishing, or substrates that have only been cleaned with a cleaning solution.

[0024] First, a bonding paste 100 made of a material that forms a bonding layer 13 is applied to the bonding surface P1 of the first ceramic substrate 11 (paste application step: see Figure 5). The bonding paste 100 is, for example, aluminum nitride processed into a paste when forming the bonding layer 13 with aluminum nitride. The bonding paste is applied to the substrate by, for example, a printing method. Layer width T of bonding paste 100 100 This is adjusted, for example, by the viscosity of the material and the amount of material that protrudes from the nozzle.

[0025] Subsequently, the bonding surface P2 of the second ceramic substrate 12 and the surface of the first ceramic substrate 11 coated with bonding paste 100 are brought together, and a load is applied to bond the ceramic substrates together (bonding step: see Figure 6). Bonding conditions include, for example, heating to 850°C or higher and 1050°C or lower under a rare gas atmosphere, and a bonding load of 102 kg / m². 2 The substrate is pressed with this load.

[0026] In a joint formed in this manner, the layer width T 100When a glass paste having a thickness in the range of 18.9 μm to 27.7 μm is applied to a substrate and bonded according to the above bonding conditions, a bonded layer 13 is formed with a layer width T1 of 25.7 μm to 34.9 μm. In this case, when the layer width T1 of the bonded layer 13 is 34.9 μm, which is the maximum within the above range, in order to secure the first region R1, it is preferable that the surface roughness Ra of the bonded surfaces P1 and P2 be 8.7 μm or less (greater than 0.5 μm), assuming that the distribution of the surface roughness of the substrate is a sinusoidal curve. In this case, in order to ensure bonding strength while suppressing an increase in the layer width of the bonding layer 13, it is preferable that the ratio of the sum of the areas of the first region R1 (S1), the second region (S2), and the third region (S3) ((S1+S2+S3) / (S2+S3)) to the sum of the area of ​​the second region (S2+S3) and the area of ​​the third region (S2+S3) is 3.39 or more and 4.36 or less.

[0027] In the embodiment described above, the bond comprises a first ceramic substrate 11, a second ceramic substrate 12, and a bonding layer 13. In the cross-section of the bonding layer 13, a first line segment L1 is non-interfering with the bonding interface of the second ceramic substrate 12, and a second line segment L2 is non-interfering with the bonding interface of the first ceramic substrate 11. The bond has a first region R1 formed by the first line segment L1 and the second line segment L2. According to this embodiment, by forming a bonding layer 13 that satisfies the above relationship, a region consisting only of the bonding layer component is reliably secured in terms of layer width, and a bonded body with high bonding strength can be obtained.

[0028] In this embodiment, an example was described in which bonding paste is applied only to the bonding surface P1 of the first ceramic substrate 11. However, bonding paste may also be applied to the bonding surface P2 of the second ceramic substrate 12, and the bonding pastes may be brought together to bond the ceramic substrates. [Examples]

[0029] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by the following examples.

[0030] (Example 1) <First and second ceramic substrates> Aluminum nitride (φ19.8mm, thickness 2mm) <Bonding paste> Glass paste: AP5717B (SiO2·ZnO·RO, R is an alkaline earth metal: Manufactured by Asahi Glass Co., Ltd.; viscosity 150 Pa·s) <Joining conditions> Heating (firing) conditions: Room temperature to 850°C (heating for 15 minutes), hold at 850°C for 20 minutes. Atmosphere: Argon (Ar) Weight load: 102kg / cm 2 Under the above conditions, ceramic substrates were joined together using the bonding method described above. The bonding paste was applied to the substrates by printing it onto the substrates using ST-110 manufactured by ESPEC Corporation and drying it at 120°C for 40 minutes.

[0031] In Example 1, the thickness of the bonding paste printed on the substrate was 26.2 μm. The thickness of the bonding paste was measured by first using a laser microscope (objective lens magnification 10x) to continuously measure the thickness across the substrate coated with the bonding paste using a laser. Then, line analysis (profile analysis) was performed on an arbitrary point on the film surface after the continuous measurement, and an arbitrary point on the partially exposed aluminum nitride substrate surface was set as the reference point (height zero). The difference (vertical direction) between two arbitrary points in the center of the film and the reference point was measured, and the average value of the two points was taken as the thickness. Figure 7 shows an SEM image of the joint according to Example 1. The SEM image was acquired at an acceleration voltage of 10.0 kV and a magnification of 1000x.

[0032] (Example 2) In Example 2, the bonded body was prepared in the same manner as in Example 1, except that the bonding paste used was AP5577 (SiO2·ZnO·RO, where R is an alkaline earth metal: manufactured by Asahi Glass Co., Ltd.), which is a glass paste. AP5577 has a viscosity of 190 Pa·s. In Example 2, the thickness of the bonding paste printed on the substrate was 18.9 μm. Figure 8 shows an SEM image of the joint according to Example 2.

[0033] (Example 3) In Example 3, a bonded body was prepared in the same manner as in Example 1, except that the bonding paste used was HHR-1010 (SiO2·CaO·ZnO: manufactured by Asahi Glass Co., Ltd.), a glass paste, and the heating (firing) conditions were from room temperature to 1050°C (heating for 23 minutes), followed by holding at 1050°C for 20 minutes. HHR-1010 has a viscosity of 74 Pa·s. In Example 3, the thickness of the bonding paste printed on the substrate was 27.7 μm. Figure 9 shows an SEM image of the joint according to Example 3.

[0034] Furthermore, for the joints relating to Examples 1 to 3, the cross-sections were observed using SEM images, and the area S1 of the first region R1, the area S2 of the second region, the area S3 of the third region, their sum ((S1+S2+S3), (S2+S3)), and the ratio ((S1+S2+S3) / (S2+S3)) were calculated.

[0035] Furthermore, the bonding layer width and bonding strength of the joints according to Examples 1 to 3 were measured. <Measuring the width of the bonding layer> The bonded body was cut with a blade saw and then polished. The polished surface was observed using a field emission scanning electron microscope under conditions of an acceleration voltage of 10.0 kV and a magnification of 1 kx. The length from the boundary between the first ceramic substrate and the bonded layer to the boundary between the second ceramic substrate and the bonded layer was measured at three different locations, and the average value of these measurements was defined as the bonded layer width. <Measuring joint strength> In accordance with JIS standard JIS R1601:2008, a load was applied to the joint layer of the joint, and the three-point bending strength was measured and defined as the joint strength.

[0036] Table 1 shows the bonding paste, bonding conditions, and characteristics of the bonded bodies for Examples 1 to 3.

[0037] [Table 1]

[0038] As shown in Table 1, in Examples 1 to 3, the joint strength was 43 MPa or higher in each case, indicating that a joint with high joint strength can be obtained if the area ratio of the joint layer ((S1+S2+S3) / (S2+S3)) is between 3.39 and 4.36. Furthermore, according to Examples 1 to 3, regardless of the width of the joint layer, the smaller the area ratio ((S1+S2+S3) / (S2+S3)), the higher the joint strength. [Explanation of symbols]

[0039] 1 zygote 11. First ceramic substrate 12. Second ceramic substrate 13 Bonding layer 100 Bonding Paste

Claims

1. A first ceramic substrate and A second ceramic substrate and A bonding layer provided between the first and second ceramic substrates to join the first and second ceramic substrates, Equipped with, In the cross-section of the bonding layer, the cutting plane is a plane parallel to the stacking direction of the first and second ceramic substrates, The bonding interface of the first ceramic substrate has a first region formed by the first line segment and the second line segment, wherein a first line segment of the bonding interface of the first ceramic substrate passes through the position closest to the second ceramic substrate in the stacking direction and is perpendicular to the stacking direction in cross-section, and is non-interfering with the bonding interface of the second ceramic substrate, and a second line segment of the bonding interface of the second ceramic substrate passes through the position closest to the first ceramic substrate in the stacking direction and is perpendicular to the stacking direction in cross-section, and is non-interfering with the bonding interface of the first ceramic substrate. zygote.

2. The surface roughness Ra of the bonding interface between the first and second ceramic substrates is greater than 0.5 μm. The joint according to claim 1.

3. The ratio of the sum of the areas of the first region, the second region, and the third region to the sum of the areas of the second region formed by the bonding interface of the first line segment and the first ceramic substrate and the area of ​​the third region formed by the bonding interface of the second line segment and the second ceramic substrate is 3.39 or more and 4.36 or less. The joint according to claim 1.

4. The bonding layer is made of an amorphous material. The joint according to claim 1.

5. A bonding method for bonding ceramic substrates, each having a surface roughness Ra greater than 0.5 μm, A paste application step in which a bonding paste having a thickness of 18.9 μm to 27.7 μm is applied to the bonding surface of one of the ceramic substrates, The bonding surface of the other ceramic substrate and the glass paste coated surface of one of the ceramic substrates are brought together and heated in a rare gas atmosphere to 850°C to 1050°C, resulting in a load of 102 kg / m². 2 A bonding step in which ceramic substrates are joined together while being pressed with a load, A joining method that includes [a specific type of joining].

6. The width of the bonding layer that joins the ceramic substrates is 25.7 μm or more and 34.9 μm or less. When the width of the bonding layer is 34.9 μm, the surface roughness Ra of the bonding surface is 8.7 μm or less. The joining method according to claim 5.

7. The paste application step involves applying the bonding paste, which is formed using an amorphous material, to the bonding surface of the ceramic substrate. The joining method according to claim 5.

8. The paste application step involves applying bonding paste to the bonding surface of one ceramic substrate and the bonding surface of the other ceramic substrate. The bonding step involves joining the ceramic substrates together by bringing the bonding paste-coated surfaces together. The joining method according to claim 5.

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