Laminate, heat dissipation substrate, and method for manufacturing laminate

Abstract

To provide a thin laminate with excellent thermal conductivity, a heat dissipation substrate, and a method for manufacturing the laminate.SOLUTION: The laminate 1 has a metal substrate 2, a metal layer 3, and an inorganic insulating layer 4 in order in the direction of thickness. The thickness of the inorganic insulating layer 4 is 10 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laminate, a heat dissipation substrate, and a method for manufacturing the laminate. [Background technology]

[0002] A laminate having a metal layer, an alloy layer, and a ceramic layer in that order in the thickness direction is known (see, for example, Patent Document 1 below). In the laminate described in Patent Document 1, the thickness of the ceramic layer is 635 μm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-135373 A Summary of the Invention [Problem to be solved by the invention]

[0004] The laminate is required to be thin and have excellent thermal conductivity, but the laminate described in Patent Document 1 may not satisfy these requirements.

[0005] The present invention provides a thin laminate having excellent thermal conductivity, a heat dissipation substrate, and a method for manufacturing the laminate. [Means for solving the problem]

[0006] The present invention (1) includes a laminate comprising a metal substrate, a metal layer, and an inorganic insulating layer in that order in the thickness direction, the inorganic insulating layer having a thickness of 10 μm or less.

[0007] The present invention (2) includes the laminate according to (1), in which the material of the metal substrate is copper or a copper alloy.

[0008] The present invention (3) includes the laminate according to (1) or (2), in which the material of the inorganic insulating layer is at least one selected from the group consisting of oxides, nitrides, and oxynitrides.

[0009] The present invention (4) includes the laminate according to any one of (1) to (3), wherein the material of the inorganic insulating layer contains at least one selected from the group consisting of aluminum, magnesium, zinc, silicon, yttrium, and titanium.

[0010] The present invention (5) includes the laminate according to any one of (1) to (4), in which the work function of the metal layer is the same as or higher than the work function of the metal substrate.

[0011] The present invention (6) includes the laminate according to any one of (1) to (5), in which the redox potential of the metal layer is lower than the redox potential of the metal substrate.

[0012] The present invention (7) includes the laminate according to any one of (1) to (6), wherein the metal substrate includes one surface and another surface in a thickness direction and a side surface connecting a peripheral edge of the one surface and a peripheral edge of the other surface, and the metal layer is disposed on the one surface and the side surface of the metal substrate.

[0013] The present invention (8) includes a heat dissipation substrate comprising the laminate according to any one of (1) to (7).

[0014] The present invention (9) is a method for producing the laminate according to any one of (1) to (7), and includes the method for producing a laminate, which comprises forming a metal layer on one surface of a metal substrate in a thickness direction by using a vacuum film-forming method, and forming an inorganic insulating layer on a surface of the metal layer by using a vacuum film-forming method. Effect of the Invention

[0015] The laminate produced by the production method of the present invention and the heat dissipation substrate including the laminate are thin and have excellent thermal conductivity. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view of one embodiment of a laminate of the present invention. [Diagram 2] FIG. 11 is a cross-sectional view of a laminate of a first modified example. [Diagram 3] FIG. 11 is a cross-sectional view of a laminate according to a second modified example. [Figure 4] FIG. 13 is a cross-sectional view of a laminate according to a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 1. One embodiment of the laminate An embodiment of the laminate of the present invention will be described with reference to FIG. 1. The laminate 1 has a thickness. The laminate 1 has a plate shape. In this embodiment, the laminate 1 has a rectangular plate shape. The laminate 1 extends in a planar direction. The planar direction is perpendicular to the thickness direction. The laminate 1 includes a metal substrate 2, a metal layer 3, and an inorganic insulating layer 4.

[0018] 1.1 Metal substrate 2 The metal substrate 2 has a plate shape. In this embodiment, the metal substrate 2 has a rectangular plate shape. The metal substrate 2 includes one surface 21 and another surface 22 in the thickness direction, and a side surface 23 connecting the peripheral edge of the one surface 21 and the peripheral edge of the other surface 22.

[0019] Each of the first surface 21 and the second surface 22 has a flat shape. The first surface 21 and the second surface 22 are parallel to each other. The first surface 21 and the second surface 22 are perpendicular to the thickness direction.

[0020] The side surface 23 is aligned along the thickness direction. In this embodiment, the side surface 23 is perpendicular to the one surface 21 and the other surface 22.

[0021] 1.1.1 Work function of metal substrate 2 The work function of the metal substrate 2 is not limited. The work function is the amount of work required to transfer one electron from the surface of the member (metal substrate 2) to the external vacuum. The work function of the metal substrate 2 depends on the material of the metal substrate 2 (described later). The work function of the metal substrate 2 is, for example, 4.0 eV or more, and, for example, 5.2 eV or less, preferably 5.1 eV or less. The work function of the metal substrate 2 is measured, for example, by X-ray photoelectron spectroscopy. The work function of the metal substrate 2 can also be obtained from literature values ​​based on the material of the metal substrate 2 (described later).

[0022] 1.1.2 Oxidation-reduction potential of metal substrate 2 The redox potential of the metal substrate 2 is not limited. The redox potential may be referred to as a standard redox potential or a standard electrode potential. The redox potential of the metal substrate 2 depends on the material of the metal substrate 2 (described later). The redox potential of the metal substrate 2 is, for example, 2.0 V or less, preferably 1.0 V or less, more preferably 0.5 V or less, and for example, 0.0 V or more, preferably 0.2 V or more. The redox potential is measured, for example, by cyclic voltammetry. The redox potential of the metal substrate 2 can also be obtained from literature values ​​based on the material of the metal substrate 2 (described later).

[0023] 1.1.3 Material of metal substrate 2 There is no limitation on the material of the metal substrate 2. The material of the metal substrate 2 is preferably copper or a copper alloy.

[0024] The metal substrate 2 has a thickness of, for example, 30 μm or more, preferably 50 μm or more, and for example, 1000 μm or less, preferably 500 μm or less.

[0025] 1.2 Metal layer 3 The metal layer 3 is disposed on one side 21 of the metal substrate 2. The metal layer 3 contacts the entire one side 21 of the metal substrate 2. The metal layer 3 follows the shape of the one side 21. In this embodiment, the metal layer 3 has a shape extending in the planar direction. The metal layer 3 has an inner surface 31 and an outer surface 32. The inner surface 31 contacts the entire one side 21. The outer surface 32 is spaced apart from one side of the inner surface 31 in the thickness direction.

[0026] 1.2.1 Work function of metal layer 3 The work function of the metal layer 3 is not limited. In this embodiment, the work function of the metal layer 3 is preferably the same as or higher than the work function of the metal substrate 2, and more preferably higher than the work function of the metal substrate 2. If the work function of the metal layer 3 is the same as or higher than the work function of the metal substrate 2, the energy barrier at the interface between the metal layer 3 and the inorganic insulating layer 4 increases, and therefore the insulation resistance of the laminate 1 can be increased. Note that the above-mentioned "same" includes the case where the two are very similar, and includes the range where the ratio of the work function of the metal layer 3 to the work function of the metal substrate 2 is 0.95 or more and 1.05 or less. The work function of the metal layer 3 depends on the material of the metal layer 3 (described later).

[0027] The work function of the metal layer 3 is, for example, 4.0 eV or more, preferably 4.6 eV or more, more preferably 5.0 eV or more, and for example, 6 eV or less. The work function of the metal layer 3 is obtained in the same manner as the work function of the metal substrate 2 described above.

[0028] The ratio of the work function of the metal layer 3 to the work function of the metal substrate 2 is preferably 1 or more, more preferably 1.10 or more, and even more preferably 1.15 or more. The value obtained by subtracting the work function of the metal substrate 2 from the work function of the metal layer 3 is preferably 0 eV or more, more preferably 0.1 eV or more, even more preferably 0.3 eV or more, particularly preferably 0.5 eV or more, and is, for example, 2.0 eV or less, preferably 1.5 eV or less, and more preferably 1.0 eV or less. If the above ratio and / or value is equal to or greater than the above lower limit, the insulation resistance of the laminate 1 can be further increased.

[0029] 1.2.2 Oxidation-reduction potential of metal layer 3 The redox potential of the metal layer 3 is not limited. In this embodiment, the redox potential of the metal layer 3 is preferably lower than that of the metal substrate 2. If the redox potential of the metal layer 3 is lower than that of the metal substrate 2, the adhesion of the metal layer 3 to the metal substrate 2 can be improved, and therefore the adhesion of the inorganic insulating layer 4 to the metal substrate 2 can be improved. The redox potential of the metal layer 3 depends on the material of the metal layer 3 (described later).

[0030] The redox potential of the metal layer 3 is preferably 0.0 V or less, more preferably −0.5 V or less, further preferably −1.0 V or less, and for example, −3.0 V or more, preferably −2.0 V or more. The redox potential of the metal layer 3 is obtained in the same manner as the redox potential of the metal substrate 2 described above.

[0031] The value obtained by subtracting the redox potential of the metal substrate 2 from the redox potential of the metal layer 3 is preferably 0 V or more, more preferably 0.7 V or more, even more preferably 1.0 V or more, and particularly preferably 1.2 V or more, and is, for example, 2.0 V or less. When the above value is equal to or more than the above lower limit, the adhesion of the inorganic insulating layer 4 to the metal substrate 2 can be further improved.

[0032] 1.2.3 Material of Metal Layer 3 The material of the metal layer 3 is not limited. In this embodiment, the material of the metal layer 3 is different from the material of the metal substrate 2. Examples of the material of the metal layer 3 include high work function metals and adhesive metals. The high work function metals and the adhesive metals are not clearly distinguished from each other and may overlap. In other words, metals that are both high work function metals and adhesive metals are also included in the metals. Examples of the above metals include nickel.

[0033] Examples of high work function metals include gold (Au), platinum (Pt), palladium (Pd), silver (Ag), cobalt (Co), iridium (Ir), ruthenium (Ru), rhodium (Rh), nickel (Ni), iron (Fe), tungsten (W), molybdenum (Mo), zinc (Zn), and tantalum (Ta). The work function of the high work function metal is, for example, 4.6 eV or more.

[0034] Examples of adhesive metals include nickel, iron, tungsten, molybdenum, zinc, tantalum, titanium (Ti), and chromium (Cr). The oxidation-reduction potential of the adhesive metal is, for example, 0 V or less, preferably −0.2 V or less.

[0035] 1.2.4 Thickness of Metal Layer 3 The thickness of the metal layer 3 is, for example, 1 nm or more, preferably 10 nm or more, and for example, 500 nm or less, preferably 100 nm or less. The ratio of the thickness of the metal layer 3 to the thickness of the metal substrate 2 is, for example, 0.000001 or more, preferably 0.00001 or more, and for example, 0.0167 or less, preferably 0.0034 or less.

[0036] 1.3 Inorganic insulating layer 4 The inorganic insulating layer 4 is disposed on the outer surface 32 of the metal layer 3. The inorganic insulating layer 4 contacts the entire outer surface 32. The inorganic insulating layer 4 forms one surface (exposed surface) of the laminate 1 in the thickness direction. The inorganic insulating layer 4 follows the shape of the outer surface 32. In this embodiment, the inorganic insulating layer 4 has a shape extending in the planar direction. The inorganic insulating layer 4 is a single layer or multiple layers. The inorganic insulating layer 4 is crystalline or amorphous.

[0037] 1.3.1 Materials for the inorganic insulating layer 4 Examples of the material of the inorganic insulating layer 4 include inorganic substances. Examples of the inorganic substances include oxides, nitrides, and oxynitrides. The material of the inorganic insulating layer 4 contains at least one selected from the group consisting of aluminum, magnesium, zinc, silicon, yttrium, and titanium. Examples of the material include silicon, aluminum, and titanium. The above-mentioned materials can be used alone or in combination.

[0038] The oxide may be, for example, aluminum oxide (Al 2 O 3 ), magnesium oxide (MgO), zinc oxide (ZnO), silicon oxide (SiO 2 ), yttrium oxide (Y 2 O 3 ), and chromium oxide (Cr 2 O 3、 CrO 2、 CrO 3 ) are mentioned.

[0039] Nitrides include, for example, silicon nitride and aluminum nitride.

[0040] Examples of oxynitrides include silicon oxynitride and aluminum oxynitride.

[0041] As the inorganic substance, preferably, an oxide is used.

[0042] 1.3.2 Thickness of inorganic insulating layer 4 The inorganic insulating layer 4 has a thickness of 10 μm or less.

[0043] On the other hand, if the thickness of the inorganic insulating layer 4 exceeds 10 μm, the inorganic insulating layer 4 becomes thick, the laminate 1 becomes large, and further, the thermal conductivity of the inorganic insulating layer 4 becomes poor, which in turn causes the thermal conductivity of the laminate 1 to become poor.

[0044] On the other hand, the thickness of the inorganic insulating layer 4 is preferably 5 μm or less, more preferably 2 μm or less, more preferably 1 μm or less, and even more preferably 0.5 μm or less.

[0045] The inorganic insulating layer 4 has a thickness of, for example, 10 nm or more, preferably 20 nm or more, more preferably 30 nm or more, and even more preferably 40 nm or more. When the inorganic insulating layer 4 has a thickness equal to or more than the above-mentioned lower limit, the laminate 1 has excellent insulating properties.

[0046] The ratio of the thickness of the inorganic insulating layer 4 to the thickness of the metal substrate 2 is, for example, 0.00001 or less, preferably 0.0001 or less, and for example, 0.35 or more, preferably 0.1 or more. The ratio of the thickness of the inorganic insulating layer 4 to the thickness of the metal layer 3 is, for example, 0.01 or less, preferably 0.1 or less, and for example, 100 or more, preferably 10 or more. The ratio of the thickness of the inorganic insulating layer 4 to the thickness of the laminate 1 is, for example, 0.01 or less, preferably 0.1 or less, and for example, 100 or more, preferably 10 or more.

[0047] 1.4 Manufacturing method of the laminate 1 A method for producing the laminate 1 will be described. To produce the laminate 1, first, a metal substrate 2 is prepared, and then a metal layer 3 is formed on one surface 21 of the metal substrate 2 by using a vacuum film-forming method. Examples of the vacuum film-forming method include a vapor deposition method, a sputtering method, and an ion plating method. A preferred example of the vacuum film-forming method is a sputtering method.

[0048] Thereafter, the inorganic insulating layer 4 is formed on the outer surface 32 of the metal layer 3 by using a vacuum film-forming method. The film-forming conditions for the inorganic insulating layer 4 may be different from the film-forming conditions for the metal layer 3, or may be the same.

[0049] 1.5 Uses of Laminate 1 The use of this laminate 1 is not limited. Preferably, the laminate 1 is provided in a heat dissipation substrate 10. That is, the heat dissipation substrate 10 includes the laminate 1 described above. The heat dissipation substrate 10 may further include an electrode 5 (virtual line) arranged on one surface of the laminate 1 in the thickness direction. The electrode 5 has a pattern. The electrode 5 is arranged on a part of one surface of the inorganic insulating layer 4 in the thickness direction. The electrode 5 is made of a conductor. Examples of the conductor include copper and titanium. The electrode 5 is a single layer or multiple layers.

[0050] 2. Effects of one embodiment In this laminate 1, the inorganic insulating layer 4 has a thickness of 10 μm or less, so that the laminate 1 is thin and has even more excellent thermal conductivity.

[0051] Furthermore, if the work function of the metal layer 3 is the same as or higher than the work function of the metal substrate 2, the energy barrier at the interface between the metal layer 3 and the inorganic insulating layer 4 increases, thereby increasing the insulation resistance of the laminate 1.

[0052] Furthermore, if the oxidation-reduction potential of the metal layer 3 is lower than the work function of the metal substrate 2, the adhesion of the metal layer 3 to the metal substrate 2 can be improved, and therefore the adhesion of the inorganic insulating layer 4 to the metal substrate 2 can be improved.

[0053] In the method for producing the laminate 1, the metal layer 3 is formed by a vacuum film-forming method, and the inorganic insulating layer 4 is also formed by a vacuum film-forming method, so that each of the metal layer 3 and the inorganic insulating layer 4 can be easily formed.

[0054] 3. Modifications

[0055] In the following modifications, the same components and steps as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In addition, each modification can achieve the same effects as those in the above-described embodiment, unless otherwise specified. Furthermore, the embodiment and the modifications can be appropriately combined.

[0056] 3.1 First modified example 2, in the laminate 1 of the first modified example, the metal layer 3 is disposed on one surface 21 and the side surface 23 of the metal substrate 2. The metal layer 3 continuously covers the one surface 21 and the side surface 23. The metal layer 3 follows the shapes of the one surface 21 and the side surface 23. The metal layer 3 disposed on the side surface 23 has a shape extending in the thickness direction.

[0057] In a first variant, the inorganic insulating layer 4 is arranged on the outer surface 32 of the metal layer 3. The inorganic insulating layer 4 contacts the entire outer surface 32 of the metal layer 3.

[0058] 3.1.1 Effects of the First Modification In the laminate 1 of the first modified example, the metal layer 3 is also formed on the side surface 23 of the metal substrate 2, so that the laminate 1 has excellent thermal conductivity on the side surface.

[0059] 3.2 Second variant 3, in the laminate 1 of the second modified example, the metal layer 3 is disposed on one surface 21, the other surface 22, and a side surface 23 of the metal substrate 2. The metal layer 3 continuously covers the one surface 21, the other surface 22, and the side surface 23.

[0060] The inorganic insulating layer 4 is disposed on the outer surface 32 of only the metal layer 3 disposed on one surface 21 .

[0061] 3.3 Third variant 4, the third modification includes the metal layer 3 of the second modification. The inorganic insulating layer 4 is disposed on the outer surface 32 of the metal layer 3 disposed on one surface 21 and the outer surface 32 of the metal layer 3 disposed on the side surface 23. EXAMPLES

[0062] The present invention will be described in more detail below with reference to examples. Note that the present invention is not limited to the examples. In addition, the specific numerical values ​​of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit (a numerical value defined as "not more than" or "less than") or lower limit (a numerical value defined as "not less than" or "exceeding") of the corresponding blending ratio (content ratio), physical property values, parameters, etc. described in the above "Form for carrying out the invention".

[0063] <Example 1> A metal substrate 2 was prepared. The metal substrate 2 had a thickness of 150 μm and was made of copper.

[0064] Next, a metal layer 3 made of platinum (Pt) and having a thickness of 50 nm was formed by vacuum film formation under the following film formation conditions.

[0065] Vacuum deposition method: DC magnetron sputtering method Sputtering gas: Ar Sputtering pressure: 0.2Pa Output: 80W Sputtering temperature: 25℃

[0066] Next, silica oxide (SiO 2 ) and an inorganic insulating layer 4 having a thickness of 50 nm was formed. The film formation conditions were as follows.

[0067] Vacuum deposition method: RF magnetron sputtering method Sputtering gas: Ar / O 2 Gas mixtures Sputtering pressure: 0.2Pa Output: 100W Sputtering temperature: 25℃

[0068] <Examples 2 to 6> A laminate 1 was produced in the same manner as in Example 1. However, the material of the metal layer 3 was changed as shown in Table 1.

[0069] <Comparative Example 1> A laminate 1 was produced in the same manner as in Example 1. However, the thickness of the inorganic insulating layer 4 was changed as shown in Table 1.

[0070] <Evaluation> 1. Thermal conductivity The area-standardized thermal resistance was calculated from the cross-sectional area and thermal conductivity of the inorganic insulating layer 4 per unit length. The thermal conductivity was evaluated from the area-standardized thermal resistance according to the following criteria. The results are shown in Table 1.

[0071] ○: The area-standardized thermal resistance of the inorganic insulating layer 4 is 1000×10 -8 KW -1 m -2 The thermal conductivity was good. ×: The area-standard thermal resistance of the inorganic insulating layer 4 is 1000×10 -8 KW -1 m -2 As a result, the thermal conductivity was poor.

[0072] 2.Insulation 2.1 Preparation of insulation evaluation sample

[0073] An electrode 5 was formed on one surface of the inorganic insulating layer 4 in each of the laminates 1 of Examples 1 to 6 and Comparative Example 1 through a metal mask having an opening. The electrode 5 includes a titanium layer having a thickness of 5 nm and a copper layer having a thickness of 100 nm, which are arranged in this order toward one side in the thickness direction. The electrode 5 has a length of 2.5 mm and a width of 2.5 mm.

[0074] The film formation conditions for the electrode 5 are as follows.

[0075] Vacuum deposition method: DC magnetron sputtering method Sputtering gas: Ar Sputtering pressure: 0.2Pa Output: 80W Sputtering temperature: 25℃

[0076] 2.2 Insulation resistance measurement The insulation properties of the laminate 1 of each of the examples and comparative examples were evaluated. As shown by the imaginary lines in Fig. 1, a source-measure unit (SMU) 6 was connected to each of the metal substrate 2 and the electrode 5 via a line 7. An electric field of 2 MV / cm was applied at 25°C using the source-measure unit 6, and the insulation resistance was obtained from the current value.

[0077] In the case where the insulation resistance exceeded 20 MΩ and the insulation properties were good, the sample was marked with “O” in Table 1.

[0078] 3. Adhesion (checkerboard peel test) The inorganic insulating layer 4 of each of the laminates 1 of Examples 1 to 6 and Comparative Example 1 was subjected to a cross-cut process in a checkerboard pattern. The grid was square, with a side length of 1 mm, and there were 25 grids. Next, a 24 mm wide adhesive tape (manufactured by Nichiban Co., Ltd.) was attached to the inorganic insulating layer 4, and then the adhesive tape was rapidly peeled off at a peeling angle of 180 degrees. The cross-cut portions were then visually observed.

[0079] In Table 1, a mark "O" was given when the peeled area was less than 10% and the adhesion of the inorganic insulating layer 4 to the metal substrate 2 was good.

[0080] [Table 1] [Explanation of symbols]

[0081] 1. Laminate 2 Metal Substrate 3 metal layer 4. Inorganic insulating layer 10 Heat dissipation board 21 One side 22 Other side 23 Side

Claims

1. A metal substrate, a metal layer, and an inorganic insulating layer are provided in this order in a thickness direction, The inorganic insulating layer has a thickness of 10 μm or less.

2. The laminate according to claim 1 , wherein the material of the metal substrate is copper or a copper alloy.

3. 3. The laminate according to claim 1, wherein the material of the inorganic insulating layer is at least one selected from the group consisting of oxides, nitrides, and oxynitrides.

4. 4. The laminate according to claim 1, wherein the material of the inorganic insulating layer contains at least one selected from the group consisting of aluminum, magnesium, zinc, silicon, yttrium, and titanium.

5. The laminate according to claim 1 , wherein the work function of the metal layer is equal to or higher than the work function of the metal substrate.

6. The laminate according to claim 1 , wherein the redox potential of the metal layer is lower than the redox potential of the metal substrate.

7. the metal substrate includes one surface and another surface in a thickness direction, and a side surface connecting a peripheral edge of the one surface and a peripheral edge of the other surface; The laminate according to claim 1 , wherein the metal layer is disposed on the one surface and the side surface of the metal substrate.

8. A heat dissipation substrate comprising the laminate according to claim 1 .

9. A method for producing the laminate according to any one of claims 1 to 7, A metal layer is formed on one surface of the metal substrate in a thickness direction by a vacuum deposition method; A method for producing a laminate, comprising forming an inorganic insulating layer on the surface of the metal layer by a vacuum film formation method.

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