Next, the structure

Abstract

To provide an adhesive structure that is less prone to degradation or deterioration due to heat, and also has high adhesive strength.SOLUTION: An adhesive structure includes a substrate and triangular wave-shaped protrusions on the surface of at least a portion of the substrate. The triangular wave-shaped protrusions are composed of inorganic material. The average pitch of the triangular wave-shaped protrusions is in the range of 100 nm to 1000 nm, and the average height of the triangular wave-shaped protrusions is in the range of 100 nm to 1000 nm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive structure. [Background technology]

[0002] A known adhesive structure has a substrate and a plurality of protrusions provided on the surface of the substrate. Patent Document 1 discloses an adhesive structure with protrusions whose tips are spherical with a radius of 300 nm or less and whose cross section perpendicular to the longitudinal direction has a radius of 500 nm or less. It is said that this adhesive structure with nano-level protrusions can penetrate into the unevenness of the surface of the adherend at the nano-level, thereby exerting a strong adhesive force. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2007 / 032164 Summary of the Invention [Problem to be solved by the invention]

[0004] It is preferable that the bonded structure can stably adhere and hold the adherend under various environments and is not likely to contaminate the adherend. However, the bonded structure described in Patent Document 1 is made of a resin material. The resin material may be decomposed or altered by heat, which may reduce the adhesive strength. Furthermore, the resin material may contaminate the adherend with decomposition products.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide an adhesive structure that is resistant to thermal decomposition and deterioration and has high adhesive strength. [Means for solving the problem]

[0006] In order to solve the above problems, the bonded structure of the present invention comprises:An adhesive structure that adhesively holds an object to be adhered, The substrate has a base and triangular wave-shaped protrusions provided on at least a portion of the surface of the base, and is made of an inorganic material, the pitch of the triangular wave-shaped protrusions is in the range of 100 nm to 1000 nm, and the height of the triangular wave-shaped protrusions is in the range of 100 nm to 1000 nm.

[0007] The bonded structure of the present invention comprises a substrate and triangular wave-shaped protrusions provided on at least a portion of the substrate's surface. Because the structure is made of an inorganic material, it is resistant to thermal decomposition and deterioration, and is less likely to contaminate the adherend. Furthermore, because the average pitch of the triangular wave-shaped protrusions is in the range of 100 nm to 1000 nm and the average height of the triangular wave-shaped protrusions is in the range of 100 nm to 1000 nm, the surface elasticity is high, and the triangular wave-shaped protrusions deform significantly when pressed with the adherend. Therefore, the bonded structure of this embodiment has high adhesive strength and can stably adhere and hold the adherend in a variety of environments.

[0008] Here, in the bonded structure of the present invention, the ratio of the height to the pitch of the triangular wave-shaped protrusions may be in the range of 0.8 to 2.0. In this case, the adhesive strength of the triangular wave-shaped protrusions to the adherend increases, and when the adherend separates from the triangular wave-shaped protrusions, the adhesive strength of the triangular wave-shaped protrusions is more likely to recover.

[0009] In the bonded structure of the present invention, the pitch of the triangular wave-shaped protrusions may be 500 nm or less. In this case, the narrower pitch of the triangular wave-shaped protrusions makes it easier for the triangular wave-shaped protrusions to deform in accordance with the surface shape of the adherend, thereby further improving the adhesive strength.

[0010] In the bonded structure of the present invention, the inorganic material may be a metal. In this case, the surface elastic modulus of the triangular wave-shaped protrusions is increased, improving the restoring force after deformation and improving repeatability.

[0011] In the bonded structure of the present invention, the metal may include any one of copper, a copper alloy, aluminum, an aluminum alloy, and a NiP alloy. In this case, the surface elastic modulus of the triangular wave-shaped protrusions becomes even higher, and the adhesive strength becomes even higher.

[0012] In addition, in the bonded structure of the present invention, when a spherical indenter having a diameter of 40 μm is pressed into the triangular wave-shaped protrusions using a nanoindenter under conditions of an indentation depth of at least one of 10 nm and 20 nm, the adhesive strength is 35 N / cm 2 The above configuration may be adopted. In this case, since the adhesive strength is high, it is unlikely to decompose or change in quality due to heat, and can be suitably used as an adhesive structure with high adhesive strength. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an adhesive structure that is resistant to thermal decomposition and deterioration and has high adhesive strength. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a perspective view of an adhesive structure according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a plan view of the bonded structure shown in FIG. [Figure 4] 10 is a focus curve of triangular wave-shaped protrusions of an adhesive structure according to one embodiment of the present invention. [Figure 5] FIG. 4 is a conceptual diagram showing the state (A in FIG. 4) before the probe of the nanoindenter is pressed into the triangular wave-shaped protrusions of the bonded structure according to one embodiment of the present invention. [Figure 6] FIG. 4B is a conceptual diagram showing a state in which the probe of a nanoindenter is pressed into the triangular wave-shaped protrusions of the bonded structure according to one embodiment of the present invention. [Figure 7]FIG. 4C is a conceptual diagram showing a state in which the probe of the nanoindenter that has been pressed into the triangular wave-shaped protrusions of the bonded structure according to one embodiment of the present invention is pulled up (FIG. 4C). [Figure 8] FIG. 4D is a conceptual diagram showing a state in which the probe of the nanoindenter pressed into the triangular wave-shaped protrusions of the bonded structure according to one embodiment of the present invention has been released from the bonded structure. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an adhesive structure according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] Fig. 1 is a perspective view of a bonded structure according to one embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1, and Fig. 3 is a plan view of the bonded structure shown in Fig. 1. 1 to 3, the bonded structure 1 according to this embodiment has a base 2 and triangular wave-shaped protrusions 3 provided on one surface of the base 2. The base 2 and the triangular wave-shaped protrusions 3 are integral with each other. The triangular wave-shaped protrusions 3 have the property of deforming when pressurized and restoring to their original shape when the pressurized state is released.

[0017] The bonded structure 1 is made of an inorganic material. Examples of inorganic materials include, but are not limited to, metals, ceramics, and glass. The inorganic material preferably has a melting point of 100°C or higher and a decomposition temperature of 100°C or higher, preferably a melting point of 300°C or higher and a decomposition temperature of 300°C or higher, and preferably a melting point of 500°C or higher and a decomposition temperature of 500°C or higher. The metal may be a simple metal or an alloy. Alloys include those composed of multiple metal elements and those composed of a metal element and a non-metal element. Examples of simple metals include aluminum, nickel, iron, and copper. Examples of alloys include aluminum alloys, NiP, stainless steel, and copper alloys. Examples of ceramics that can be used include oxides, nitrides, and carbides. Examples of ceramics include alumina. The inorganic material constituting the bonded structure 1 is preferably a metal, and more preferably contains copper, copper alloys, aluminum, aluminum alloys, or NiP alloys.

[0018] The substrate 2 is plate-shaped. There is no particular limitation on the size of the substrate 2. The thickness of the substrate 2 is, for example, in the range of 10 μm to 10 cm.

[0019] The triangular wave-like protrusion portion 3 is configured with a plurality of elongated protrusions 4 arranged along the longitudinal direction. The cross-sectional shape of the protrusions 4 is triangular. The cross-sectional shape of the protrusions 4 is preferably an isosceles triangle. The base angle of the protrusions 4 (θ in FIG. 2) is preferably 60 degrees or more, and is preferably in the range of 60 degrees to 80 degrees.

[0020] The average pitch of the triangular wave-shaped protrusions 3 is in the range of 100 nm or more and 1000 nm or less, and preferably 500 nm or less. The average pitch of the triangular wave-shaped protrusions 3 is the average value of the distance (P in Figures 2 and 3) between the apexes 4a of adjacent protrusions 4 of the triangular wave-shaped protrusions 3. The average pitch of the triangular wave-shaped protrusions 3 can be measured from a cross-sectional SEM photograph of the bonded structure 1 taken with an SEM (scanning electron microscope).

[0021] The average height of the triangular wave-shaped protrusions 3 is in the range of 100 nm to 1000 nm, and preferably 500 nm or less. The average height of the triangular wave-shaped protrusions 3 is the average of the heights of the protrusions 4 (H in FIG. 2 ) with the base being the space between the valleys 4b of the protrusions 4 of the triangular wave-shaped protrusions 3. The average height of the triangular wave-shaped protrusions 3 can be measured from a cross-sectional SEM photograph of the bonded structure 1 taken with an SEM.

[0022] The ratio of the average height to the average pitch of the triangular wavy protrusions 3 (average height / average pitch) is preferably in the range of 0.8 to 2.0, more preferably 1.0 to 1.5. When the average height / average pitch is 0.8 or more, the protrusions 4 are easily deformed along the adherend, improving their ability to conform to the shape of the adherend. The triangular wavy protrusions 3 are periodically arranged with protrusions 4 that have high conformability to the shape of the adherend. Therefore, when the triangular wavy protrusions 3 are pressed by the adherend, the amount of deformation of the triangular wavy protrusions 3 is large, increasing the contact area between the adherend and the triangular wavy protrusions 3. This increases the adhesive strength of the triangular wavy protrusions 3 to the adherend. Furthermore, when the average height / average pitch is 2.0 or less, when the adherend is released from the triangular wavy protrusions 3, the protrusions 4 are easily restored to their original shape, improving the recovery of the adhesive strength of the triangular wavy protrusions 3. Therefore, the triangular wave-shaped protrusions 3 can be used repeatedly for a long period of time.

[0023] The adhesive strength of the triangular wave-shaped protrusions 3 of the bonded structure 1 can be determined by creating a focus curve using a nanoindenter. Fig. 4 shows the focus curve of the triangular wave-shaped protrusion 3 of the bonded structure 1 measured using a nanoindenter. Fig. 5 is a conceptual diagram showing the state (Fig. 4A) before the probe 10 of the nanoindenter is pressed into the triangular wave-shaped protrusion 3 of the bonded structure 1. Fig. 6 is a conceptual diagram showing the state (Fig. 4B) after the probe 10 of the nanoindenter has been pressed into the triangular wave-shaped protrusion 3 of the bonded structure 1. Fig. 7 is a conceptual diagram showing the state (Fig. 4C) after the probe 10 of the nanoindenter pressed into the triangular wave-shaped protrusion 3 of the bonded structure 1 has been pulled up. Fig. 8 is a conceptual diagram showing the state (Fig. 5D) after the probe 10 of the nanoindenter pressed into the triangular wave-shaped protrusion 3 of the bonded structure 1 has been released from the bonded structure 1.

[0024] As shown in Fig. 5, when the bonded structure 1 and the probe 10 are separated, no load is applied between the triangular wave-shaped protrusion 3 of the bonded structure 1 and the probe 10 (A in Fig. 4). In this embodiment, a spherical indenter with a diameter of 40 µm was used as the probe 10.

[0025] To create a focus curve, first, the probe 10 is pressed into the triangular wave-shaped protrusion 3 of the bonded structure 1 with a predetermined load. The conditions for pressing the probe 10 vary depending on the shape of the probe 10. When the probe 10 is a spherical indenter with a diameter of 40 μm, the pressing is performed under conditions of a load of 20 μN to 100 μN and a pressing speed of 10 nm / sec to 20 nm / sec. The pressing of the probe 10 causes the triangular wave-shaped protrusion 3 of the bonded structure 1 to deform in accordance with the shape of the probe 10. As the pressing depth of the probe 10 increases, the amount of deformation of the triangular wave-shaped protrusion 3 increases. Then, as shown in FIG. 6, pressing of the probe 10 is stopped when the probe 10 has been pressed to a predetermined depth (B in FIG. 4). In this embodiment, the pressing depth of the probe 10 is set to 10 nm or 20 nm.

[0026] Next, the probe 10 is pressed into the triangular-wave-shaped protrusion 3 with a predetermined load and held there for a predetermined time, after which the probe 10 is lifted from the triangular-wave-shaped protrusion 3. The conditions for lifting the probe 10 vary depending on the shape of the probe 10. When the probe 10 is a spherical indenter with a diameter of 40 μm, the lifting speed is set to a range of 10 nm / sec to 20 nm / sec. By lifting the probe 10, the load applied to the triangular-wave-shaped protrusion 3 decreases, and the triangular-wave-shaped protrusion 3 returns to its original shape. Furthermore, when the probe 10 is lifted, the probe 10 and the triangular-wave-shaped protrusion 3 do not separate even when the load is removed, and the adhesive force is observed as a negative load. Furthermore, when the probe 10 is lifted, the probe 10 separates from the triangular-wave-shaped protrusion 3, and the load applied to the triangular-wave-shaped protrusion 3 becomes zero. Then, as shown in Figure 7, the probe 10 and the triangular-wave-shaped protrusion 3 completely separate (D in Figure 4). The maximum negative load (C in FIG. 4, unit: N) from when the negative load was observed until the probe 10 was released from the triangular wave-shaped protrusion 3 was defined as the contact area (cm 2 ) is the adhesive strength of the triangular wave-shaped protrusions 3. The adhesive strength of the triangular wave-shaped protrusions 3 varies depending on the shape of the probe 10 and the indentation depth of the probe 10. The adhesive structure 1 of this embodiment has an adhesive strength of 35 N / cm at an indentation depth of at least one of 10 nm and 20 nm. 2 It is preferable that this is equal to or greater than this.

[0027] The bonded structure 1 of this embodiment can also be produced by a method including, for example, a polishing step, a cutting step, and an etching step. In the polishing step, the surface of the raw inorganic material substrate is polished. The inorganic material substrate can be polished, for example, by grinder polishing, polishing with waterproof paper, or buff polishing. The surface of the inorganic material substrate after polishing preferably has a surface roughness Ra of 0.02 μm or less.

[0028] In the cutting process, the surface of the inorganic material substrate polished in the polishing process is cut to form triangular wave-shaped protrusions. There are no particular limitations on the cutting method, and various methods can be selected. As the cutting method, for example, a method in which a cutting tool is periodically moved up and down while moving the cutting tool in a direction perpendicular to the cutting surface to form grooves (NP method: nanopecking method), or a method in which a cutting tool is moved linearly without moving up and down to form grooves (conventional method) can be used.

[0029] In the NP method, a processing device having a cutting tool and an ultrasonic vibration device that ultrasonically vibrates the cutting tool can be used as the processing device. The shape of the cutting edge of the cutting tool is not particularly limited, and can be, for example, triangular or rectangular. In the NP method, for example, the cutting tool is ultrasonically vibrated while being pressed obliquely into the surface of the inorganic material substrate, and then the cutting tool is periodically moved up and down while being moved in a direction perpendicular to the cutting edge. This forms triangular wave-shaped protrusions on the surface of the inorganic material substrate, each having a plurality of inverted triangular grooves extending in a direction perpendicular to the movement direction of the cutting tool.

[0030] In the conventional method, a processing device having a cutting tool and an ultrasonic vibration device that ultrasonically vibrates the cutting tool can be used as the processing device. The cutting edge of the cutting tool is triangular. In the conventional method, for example, the cutting tool is pressed vertically into the surface of the inorganic material substrate while being ultrasonically vibrated, and then the cutting tool is moved in a direction perpendicular to the cutting edge while being fixed so that it does not move up and down. This forms inverted triangular grooves on the surface of the inorganic material substrate that extend parallel to the direction of movement of the cutting tool. By repeating this operation, triangular wave-shaped protrusions having multiple inverted triangular grooves that extend parallel to the direction of movement of the cutting tool are formed on the surface of the inorganic material substrate. In this way, the bonded structure 1 of this embodiment is manufactured.

[0031] The bonded structure 1 of this embodiment, configured as described above, comprises a substrate 2 and triangular wave-shaped protrusions 3 provided on at least a portion of the surface of the substrate 2. Because the triangular wave-shaped protrusions 3 are made of an inorganic material, they are resistant to thermal decomposition and deterioration, and are less likely to contaminate the adherend. Furthermore, because the average pitch of the triangular wave-shaped protrusions 3 is in the range of 100 nm to 1000 nm and the average height of the triangular wave-shaped protrusions 3 is in the range of 100 nm to 1000 nm, the surface elasticity of the triangular wave-shaped protrusions 3 is high, resulting in a large amount of deformation of the protrusions when pressed by the adherend. Therefore, the bonded structure 1 of this embodiment has high adhesive strength and can stably adhere and hold the adherend in a variety of environments.

[0032] In the bonded structure 1 of this embodiment, when the pitch of the triangular wavy protrusions 3 is 500 nm or less, the narrower pitch of the triangular wavy protrusions 3 makes it easier for the triangular wavy protrusions 3 to deform along the surface shape of the adherend, thereby further improving the adhesive strength. Furthermore, when the inorganic material constituting the triangular wavy protrusions 3 is a metal, the surface elastic modulus of the triangular wavy protrusions 3 becomes higher, improving the recovery force after deformation and repeatability. In particular, when the inorganic material constituting the triangular wavy protrusions 3 is copper, copper alloy, aluminum, aluminum alloy, or NiP alloy, the surface elastic modulus of the triangular wavy protrusions 3 becomes higher, thereby increasing the adhesive strength. Furthermore, in the bonded structure 1 of this embodiment, when a nanoindenter using a spherical indenter with a diameter of 40 μm is used as the probe 10, the probe 10 is pressed into the triangular wavy protrusions 3 under conditions of an indentation depth of at least one of 10 nm and 20 nm, the adhesive strength is 35 N / cm. 2 If the adhesive strength is above this, the adhesive strength is high, so that it is unlikely to decompose or change in quality due to heat, and can be suitably used as an adhesive structure with high adhesive strength.

[0033] In the bonded structure 1 of this embodiment, when the ratio of the average height to the average pitch of the triangular wavy protrusions 3 (average height / average pitch) is in the range of 0.8 to 2.0, the adhesive strength of the triangular wavy protrusions 3 to the adherend increases, and the adhesive strength of the triangular wavy protrusions 3 is easily restored when the adherend is detached from the triangular wavy protrusions 3. Furthermore, because the protrusions of the bonded structure 1 of this embodiment are triangular wavy, it has the effect of being less likely to have planar anisotropy in the adhesive strength.

[0034] Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the technical idea of ​​the invention. For example, in the bonded structure 1 of this embodiment, the triangular wave-shaped protrusions 3 are provided over the entire surface of one surface (upper surface) of the base 2, but the position of the triangular wave-shaped protrusions 3 is not limited to this. The triangular wave-shaped protrusions 3 may be provided on both surfaces of the base 2. Furthermore, the triangular wave-shaped protrusions 3 may be provided on a portion of the surface of the base 2. [Example]

[0035] [Example 1] A metal aluminum substrate (length: 30 mm, width: 30 mm, thickness: 30 mm) was prepared as the substrate. The surface of the prepared metal aluminum substrate was polished until the surface roughness Ra became 0.02 μm or less, to form a smooth surface.

[0036] Next, triangular wave-shaped protrusions were formed on the polished surface of the metal aluminum substrate using the NP method. The processing device used was a processing device equipped with a cutting tool and an ultrasonic vibration device that ultrasonically vibrated the cutting tool in an elliptical motion. The cutting tool was inserted obliquely while ultrasonically vibrating, and then, while ultrasonically vibrating the cutting tool, the cutting tool was moved 1000 nm in a direction perpendicular to the blade surface while the cutting edge was moved in a period in which it moved 1000 nm up and down. This formed inverted equilateral triangular grooves extending in a direction perpendicular to the direction of movement of the cutting tool on the surface of the metal aluminum substrate, thereby producing a substrate with triangular wave-shaped protrusions having equilateral triangular wave-shaped protrusions. The average pitch of the triangular wave-shaped protrusions on the substrate with triangular wave-shaped protrusions was 1000 nm, the average height was 1000 nm, and the average height / average pitch was 1.0.

[0037] [Invention Examples 2 and 3, Comparative Examples 1 and 2] A substrate with triangular wavy protrusions was produced in the same manner as in Example 1 of the present invention, except that a metal substrate made of the material listed in Table 1 below was used as the substrate, and the substrate was cut so that the average pitch, average height, and average height / average pitch of the triangular wavy protrusions were the values ​​listed in Table 1 below.

[0038] [evaluation] The surface elastic modulus and adhesive strength were measured by the following methods for the substrates with triangular wavy protrusions produced in invention examples 1 to 3 and comparative examples 1 and 2. The results are shown in Table 1.

[0039] (Method for measuring surface elastic modulus) Measurements were made using a nanoindenter (ENT-NEXUS, manufactured by Elionix Co., Ltd.). A spherical indenter (made of titanium) with a diameter of 40 μm was used as the probe. The load was increased from 20 μN to 100 μN in 10 μN increments, and the surface elastic modulus was measured at each load. The surface elastic modulus when the probe's indentation depth reached 1 / 10 of the height of the triangular wave-shaped protrusions is shown in Table 1 below. The measurements were carried out at room temperature (25°C).

[0040] (Method for evaluating adhesive strength) The adhesive strength was measured using a nanoindenter (ENT-NEXUS, manufactured by Elionix Co., Ltd.) according to the above method. A spherical indenter (made of titanium) with a diameter of 40 μm was used as the probe. The indentation depth of the spherical indenter was the depth listed in Table 1, as in the above method for measuring the surface elastic modulus. The indentation speed of the probe was set to 10 nm / sec when the indentation depth was 10 nm, and 20 nm / sec when the indentation depth was 20 nm. The lift-up speed of the probe was set to 10 nm / sec when the indentation depth was 10 nm, and 20 nm / sec when the indentation depth was 20 nm. The measurements were carried out at room temperature (25°C).

[0041] [Table 1]

[0042] From the results in Table 1, it was confirmed that the substrates with triangular wavy protrusions obtained in Invention Examples 1 to 3, in which the average pitch and average height of the triangular wavy protrusions are within the ranges of the present invention, have higher adhesive strength than the substrates with triangular wavy protrusions obtained in Comparative Examples 1 and 2, and are useful as bonded structures. The reason why the substrates with triangular wavy protrusions obtained in Invention Examples 1 to 3 have higher adhesive strength is because the surface elastic modulus is low and the amount of deformation of the protrusions is large when pressure is applied by the adherend.

[0043] The substrate with triangular wavy protrusions obtained in Comparative Example 1, in which the average pitch and average height of the triangular wavy protrusions were larger than the ranges of the present invention, had a lower adhesive strength although the average height / average pitch was the same as in Invention Examples 1 to 3. This is because the average pitch was large and the protrusion size was too large, resulting in a higher surface elastic modulus. The substrate with protrusions obtained in Comparative Example 2, in which the average pitch and average height of the triangular wavy protrusions were smaller than the ranges of the present invention, did not allow the probe to adhere, even though the average height / average pitch was the same as in Invention Examples 1 to 3. This is because the surface elastic modulus increased due to the average height becoming too small. [Industrial Applicability]

[0044] The bonded structure of this embodiment has high heat resistance and high adhesive strength, and can be used as a structure for bonding and temporary fixation. The bonded structure of this embodiment can be particularly suitably used in fields such as aerospace, semiconductors, and medicine, where the environment is subject to large changes and little contamination by impurities is required. [Explanation of symbols]

[0045] 1 Adhesive structure 2 Base 3 Triangular wave-like protrusion 4 protrusions 4a Top 4b Valley 10 probe

Claims

1. An adhesive structure for adhesively holding an adherend, comprising: a substrate and triangular wave-shaped protrusions provided on at least a part of the surface of the substrate; the triangular wave-shaped protrusions are made of an inorganic material, The average pitch of the triangular wave-shaped protrusions is in the range of 100 nm or more and 1000 nm or less, An adhesive structure in which the average height of the triangular wave-shaped protrusions is in the range of 100 nm or more and 1000 nm or less.

2. The bonded structure according to claim 1 , wherein the ratio of the average height of the triangular wave-like projections to the average pitch is in the range of 0.8 to 2.

0.

3. The bonded structure according to claim 1 or 2, wherein the average pitch of the triangular wave-shaped projections is 500 nm or less.

4. The bonded structure according to claim 1 , wherein the inorganic substance is a metal.

5. The bonded structure according to claim 4 , wherein the metal comprises any one of copper, a copper alloy, aluminum, an aluminum alloy, and a NiP alloy.

6. Using a nanoindenter, a spherical indenter with a diameter of 40 μm was pressed into the triangular wave-shaped protrusions to a depth of at least 10 nm or 20 nm, and the adhesive strength was 35 N / cm ２ The bonded structure according to any one of claims 1 to 5.

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