Mounting substrate and method for manufacturing the same

Abstract

A mounting substrate (1) is provided with a metal substrate (2) and an insulating layer (3). The insulating layer (3) is disposed on one surface (21) of the metal substrate (2) in the thickness direction. The insulating layer (3) has a plurality of inorganic insulating portions (31) and an elastic insulating portion (32). The inorganic insulating portion (31) is disposed on a first portion (211) of one surface (21) of the metal substrate (2). The plurality of inorganic insulating portions (31) are spaced apart from each other in the surface direction. The elastic insulating portion (32) is disposed on a second portion (212) of the one surface (21) of the metal substrate (2). The elastic insulating portion (32) is disposed between the inorganic insulating portions (31) adjacent to each other.

Description

Mounting board and manufacturing method thereof

[0001] The present invention relates to a mounting substrate and a manufacturing method thereof.

[0002] Mounting substrates containing metal materials are known (see, for example, Patent Document 1 below). The mounting substrate described in Patent Document 1 includes a base substrate and a thermally conductive layer disposed on the surface thereof. The base substrate includes aluminum. Pores are formed on the surface of the base substrate. The thermally conductive layer is filled in the pores. The base substrate is continuous in the planar direction at the bottom.

[0003] JP 2014-127633 A

[0004] The mounting substrate may be subjected to stress depending on the application and purpose. In the mounting substrate of Patent Document 1, the base substrate cannot sufficiently relieve the above-mentioned stress, which is problematic in that cracks are likely to occur in the base substrate.

[0005] The present disclosure provides a mounting substrate that can sufficiently relieve stress and suppress the occurrence of cracks, and a method for manufacturing the same.

[0006] The present disclosure [1] includes a mounting substrate comprising a metal substrate and an insulating layer disposed on one surface of the metal substrate in a thickness direction, the insulating layer having a plurality of inorganic insulating portions disposed on a part of the one surface of the metal substrate and spaced apart from each other in a plane direction perpendicular to the thickness direction, and elastic insulating portions disposed on the remainder of the one surface of the metal substrate and disposed between adjacent inorganic insulating portions.

[0007] In this mounting substrate, the inorganic insulating portions in the insulating layer are spaced apart in the surface direction. Therefore, even if stress is applied to one inorganic insulating portion, stress is less likely to be applied to inorganic insulating portions adjacent to the one inorganic insulating portion. Furthermore, since the inorganic insulating portions can be made small, cracks are less likely to occur in the insulating layer.

[0008] Furthermore, the insulating layer has elastic insulating portions disposed between adjacent inorganic insulating portions, which can relieve the above-mentioned stress, thereby preventing cracks from occurring in the insulating layer.

[0009] The present disclosure [2] includes the mounting board according to [1], further including a wiring layer disposed on one surface of the insulating layer in the thickness direction.

[0010] The present disclosure [3] includes the mounting board according to [1], further including a wiring layer disposed on the other surface of the metal substrate in the thickness direction.

[0011] The present disclosure [4] is a method for manufacturing a mounting substrate according to [1], the manufacturing method comprising: a step (1) of preparing a metal substrate; and a step (2) of forming an insulating layer on one surface of the metal substrate in a thickness direction, the step (2) including a step (3) of forming a resist on a part of the one surface of the metal substrate in the thickness direction; a step (4) of forming inorganic insulating portions by anodic oxidation on a remaining part of the one surface of the metal substrate exposed from the resist, the inorganic insulating portions being spaced apart from each other in a plane direction perpendicular to the thickness direction; and a step (5) of removing the resist.

[0012] The present disclosure [5] includes the method for manufacturing a mounting substrate according to [4], in which the step (2) includes, after the step (5), a step (6) of disposing a photosensitive resin composition on one surface of the inorganic insulating portion and the part to form a photosensitive layer, and forming an elastic insulating portion from the photosensitive layer by photolithography.

[0013] In the mounting board of the present invention manufactured by the manufacturing method of the present invention, the occurrence of cracks in the insulating layer can be suppressed.

[0014] FIG. 3 is a plan view of one embodiment of a mounting board of the present invention. FIG. 4 is a cross-sectional view of the mounting board shown in FIG. 1. FIG. 4 is a cross-sectional view taken along line A-A. FIG. 5 is a diagram showing steps of a method for manufacturing a mounting board. FIG. 5A is a step of preparing a metal substrate. FIG. 5B is a step of forming an oxide layer. FIG. 5C is a step of forming a resist. FIG. 5D is a step of forming an inorganic insulating portion. FIG. 5E is a step of removing the resist. FIG. 5F is a step of forming an elastic insulating portion. FIG. 5A is a cross-sectional view of a mounting board provided with a wiring layer.

[0015] 1. One embodiment of a printed circuit board

[0016] The mounting substrate 1 will be described with reference to FIGS.

[0017] As shown in Fig. 1, the mounting substrate 1 has, for example, a rectangular shape in a plan view. A plan view is synonymous with a view in the thickness direction. The mounting substrate 1 has a plate shape extending in a planar direction. The planar direction is perpendicular to the thickness direction. As shown in Fig. 2, the mounting substrate 1 includes a metal substrate 2 and an insulating layer 3.

[0018] 1.1 Metal Substrate 2 The metal substrate 2 is the other side portion of the mounting substrate 1 in the thickness direction. The metal substrate 2 extends in the surface direction. The metal substrate 2 includes one surface 21 and another surface 22. The other surface 22 is the other surface of the mounting substrate 1 in the thickness direction. The other surface 22 has a flat shape. The one surface 21 is spaced apart from the other surface 22 in the thickness direction. The one surface 21 has an uneven shape. The one surface 21 includes a plurality of first portions 211 and second portions 212.

[0019] The first portions 211 are part of the one surface 21. The first portions 211 are spaced apart from one another in the surface direction. As shown in Fig. 1 , each of the first portions 211 has, for example, a rectangular shape in a plan view.

[0020] The second portion 212 is a remaining portion of the first portion 211 on one surface 21. The second portion 212 is disposed between the first portions 211 adjacent to each other in the surface direction. The second portion 212 has, for example, a lattice shape in a plan view. As shown in FIG. 2 , the second portion 212 is located on one side of the first portion 211 in the thickness direction. The second portion 212 is connected to the first portion 211 via a connecting surface 213.

[0021] The connecting surface 213 connects the outer peripheral edge of the second portion 212 and the inner peripheral edge of the first portion 211. The connecting surface 213 extends in the thickness direction.

[0022] 1, the second portion 212 may also be arranged around the first portion 211 that is arranged at the peripheral end of the one surface 21. The second portion 212 described above has a frame shape.

[0023] The Young's modulus of the metal substrate 2 at 25°C is, for example, more than 1 GPa, preferably 10 GPa or more, more preferably 40 GPa or more, and even more preferably 50 GPa or more, and 200 GPa or less. The Young's modulus of the metal substrate 2 can be determined from the materials and literature values ​​described below. The Young's modulus of the metal substrate 2 can also be measured.

[0024] Examples of materials for the metal substrate 2 include aluminum, titanium, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, antimony, and oxides thereof. From the viewpoint of ensuring high insulation properties, preferred materials for the metal substrate 2 include aluminum and aluminum oxide (alumina).

[0025] 2, the metal substrate 2 may include an oxide layer 23 and a simple substance layer 24. The oxide layer 23 includes a second portion 212 on the one surface 21 and the other surface 22. The oxide layer 23 extends in the planar direction. The material of the oxide layer 23 is, for example, the above-mentioned oxide, preferably aluminum oxide (alumina).

[0026] The oxide layer 23 has a thickness of, for example, 100 nm or less, preferably 20 nm or less, more preferably 15 nm or less, and for example, 1 nm or more.

[0027] The simple layer 24 is disposed between the oxide layer 23 of the second portion 212 and the oxide layer 23 of the other surface 22. The simple layer 24 extends in the surface direction. The simple layer 24 in the first portion 211 on the one surface 21 is separated from (independent of) the oxide layer 23. The simple layer 24 located near the other side of the oxide layer 23 including the second portion 212 is located on one side of the first portion 211 in the thickness direction. The simple layer 24 located in the above-mentioned position is a protruding portion. The protruding portion protrudes from the first portion 211 to one side in the thickness direction in the simple layer 24.

[0028] The ratio of the thickness of the oxide layer 23 to the thickness of the simple substance layer 24 is, for example, 0.1 or less, preferably 0.01 or less, and －６The thickness of the simple layer 24 is the length between the oxide layer 23 of the second portion 212 and the oxide layer 23 of the other surface 22. Specifically, the thickness of the simple layer 24 is, for example, 30 to 300 μm.

[0029] The length of the connecting surface 213 is, for example, 0.1 μm to 10 μm, or preferably 0.3 μm to 2 μm.

[0030] The thickness T0 of the metal substrate 2 is, for example, 50 μm to 500 μm, or preferably 100 μm to 300 μm. The thickness T0 of the metal substrate 2 is the length in the thickness direction between the second portion 212 on the one surface 21 and the other surface 22.

[0031] 1.2 Insulating Layer 3 The insulating layer 3 is disposed on one surface 21 of the metal substrate 2 in the thickness direction. The insulating layer 3 is one side portion of the mounting substrate 1 in the thickness direction. The insulating layer 3 extends in the planar direction. The insulating layer 3 has a plurality of inorganic insulating portions 31 and an elastic insulating portion 32.

[0032] 1.2.1 Inorganic insulating portion 31 The inorganic insulating portions 31 are arranged on a first portion 211, which is a part of one surface 21 of the metal substrate 2. The inorganic insulating portions 31 are also arranged on the connecting surface 213. The inorganic insulating portions 31 extend in the planar direction. The inorganic insulating portions 31 are spaced apart from one another in the planar direction. As shown in FIG. 1 , each of the inorganic insulating portions 31 has, for example, a rectangular shape in a planar view. As shown in FIG. 2 , each of the inorganic insulating portions 31 has a rectangular shape in a cross-sectional view. The inorganic insulating portion 31 has one surface 311, another surface 312, and a side surface 313.

[0033] The one surface 311 has a flat shape and is located on one side of the second portion 212 in the thickness direction.

[0034] The other surface 312 is spaced apart from the one surface 311 in the thickness direction. The other surface 312 contacts the first portion 211 of the metal substrate 2. The other surface 312 has a flat shape.

[0035] The side surface 313 connects the outer peripheral edge of the one surface 311 to the outer peripheral edge of the other surface 312. The other portion of the side surface 313 in the thickness direction contacts the connecting surface 213 of the metal substrate 2. The other portion of the side surface 313 contacts the side surface of the oxide layer 23 and the side surface of the protruding portion of the simple substance layer 24.

[0036] The inorganic insulating portion 31 is called an anodic oxide film because it is formed by anodic oxidation in step (4) (see FIG. 2D, which will be described later).

[0037] The Young's modulus of the inorganic insulating portion 31 at 25°C is, for example, more than 10 GPa, preferably 50 GPa or more, more preferably 100 GPa or more, and even more preferably 300 GPa or more, and 1000 GPa or less. The Young's modulus of the inorganic insulating portion 31 can be determined from the materials and literature values ​​described below. The Young's modulus of the inorganic insulating portion 31 can also be measured.

[0038] The inorganic insulating portion 31 may be made of at least one anodic oxide selected from the group consisting of aluminum, titanium, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. The inorganic insulating portion 31 may be made of preferably aluminum oxide (alumina), more preferably γ-alumina crystal.

[0039] The inorganic insulating portion 31 has a thickness T1 of, for example, 0.1 μm to 10 μm, or preferably 0.3 μm to 2 μm. The ratio (T1 / T0) of the thickness T1 of the inorganic insulating portion 31 to the thickness T0 of the metal substrate 2 is, for example, 0.001 to 0.1, or preferably 0.003 to 0.01.

[0040] The minimum length L1 in the planar direction of the inorganic insulating portion 31 is, for example, 1000 μm or less, preferably 500 μm or less, more preferably 200 μm or less, and is 10 μm or more. If the inorganic insulating portion 31 has a rectangular shape in a planar view, the minimum length L1 corresponds to the short side. If the minimum length L1 in the planar direction of the inorganic insulating portion 31 is equal to or less than the above-mentioned upper limit, the inorganic insulating portion 31 can be made small, and cracks in the insulating layer 3 can be effectively suppressed.

[0041] 1.2.2 Elastic insulating portion 32 The elastic insulating portion 32 is disposed in the second portion 212, which is the remaining portion of one surface 21 of the metal substrate 2. Furthermore, a portion of the elastic insulating portion 32 is disposed between adjacent inorganic insulating portions 31. The elastic insulating portion 32 has a filling portion 321.

[0042] The filling portion 321 is disposed between one side portions of the side surfaces 313 of adjacent inorganic insulating portions 31. The filling portion 321 fills the recess 30. The recess 30 is defined by the second portion 212 and the two side surfaces 313. The filling portion 321 contacts the second portion 212 and the two side surfaces 313. The filling portion 321 has the same shape as the recess 30.

[0043] The thickness T21 of the filling portion 321 is, for example, 0.1 μm to 10 μm, or preferably 0.3 μm to 2 μm. The thickness T21 of the filling portion 321 is the length in the thickness direction between the second portion 212 of the metal substrate 2 and the one surface 311 of the inorganic insulating portion 31.

[0044] The width W21 of the filling portion 321 is, for example, 1 μm to 100 μm, or preferably 5 μm to 50 μm. The width W21 of the filling portion 321 is the length between the side surfaces 313 of the adjacent inorganic insulating portions 31.

[0045] The elastic insulating portion 32 further includes a bulging portion 322 in addition to the filling portion 321. The bulging portion 322 bulges from one edge of the filling portion 321 in the thickness direction toward one side in the thickness direction and outward in the surface direction. The peripheral edge of the bulging portion 322 contacts the peripheral edge of one surface 311 of the inorganic insulating portion 31. The bulging portion 322 spans adjacent inorganic insulating portions 31. The elastic insulating portion 32 has a T-shape in cross section. One surface of the elastic insulating portion 32 in the thickness direction is located on one side of the second portion 212 of the metal substrate 2 in the thickness direction.

[0046] The thickness T22 of the bulging portion 322 is, for example, more than 0 μm and not more than 10 μm, preferably 0.1 μm to 5 μm. The thickness T22 of the bulging portion 322 is the length in the thickness direction between one surface of the bulging portion 322 and one surface 311 of the inorganic insulating portion 31.

[0047] The width W22 of the bulging portion 322 is in the range of, for example, 1 μm to 120 μm, or preferably 5 μm to 60 μm.

[0048] The thickness T2 of the elastic insulating portion 32 is 0.1 μm to 10 μm, preferably 0.4 μm to 5 μm. The thickness T2 of the elastic insulating portion 32 is the sum of the thickness T21 of the filling portion 321 and the thickness T22 of the bulging portion 322. The width W2 of the elastic insulating portion 32 is the same as the width W22 of the bulging portion 322. The ratio (T1 / T2) of the thickness T1 of the inorganic insulating portion 31 to the thickness T2 of the elastic insulating portion 32 is, for example, 0.05 to 2, preferably 0.1 to 1.

[0049] The Young's modulus of the elastic insulating portion 32 at 25°C is, for example, 7 GPa or less, preferably 5 GPa or less, and is, for example, 0.1 GPa or more. Since the Young's modulus of the elastic insulating portion 32 is equal to or less than the above-mentioned upper limit, the elastic insulating portion 32 can efficiently relieve stress applied to the insulating layer 3. The Young's modulus of the elastic insulating portion 32 can be determined from the materials and literature values ​​described below. The Young's modulus of the elastic insulating portion 32 can also be measured.

[0050] Resin is an example of the material for the elastic insulating portion 32. Examples of resin include polyimide resin, epoxy resin, phenol resin, and polyparaphenylenebenzoxazole resin (PBO).

[0051] 1.2 Manufacturing Method of Mounting Substrate Next, a manufacturing method of the mounting substrate 1 will be described with reference to Figures 3A to 3F. This manufacturing method includes steps (1) and (2). Steps (1) and (2) are performed in this order.

[0052] 3A and 3B, in step (1), a metal substrate 2 is prepared. Specifically, first, as shown in FIG. 3A, a metal substrate 2 made of a simple substance layer 24 is prepared.

[0053] 3B, oxide layers 23 are formed on one and the other surfaces of the element layer 24 in the thickness direction. Specifically, the element layer 24 is heated in the air. The heating time is, for example, 400°C to 800°C. The heating time is, for example, 10 minutes to 5 hours.

[0054] In this way, the metal substrate 2 having the simple substance layer 24 and the two oxide layers 23 is prepared.

[0055] 1.2.2 Step (2) As shown in FIG. 3F, in step (2), the insulating layer 3 is formed on one surface 21 of the metal substrate 2 in the thickness direction.

[0056] Step (2) includes steps (3), (4), (5), and (6). Steps (3), (4), (5), and (6) are performed in this order.

[0057] As shown in Fig. 3C , in step (3), resist 5 is formed on a second portion 212 (remaining portion) of one surface 21 of metal substrate 2 in the thickness direction. Specifically, as shown by the imaginary line in Fig. 3C , first, a photosensitive dry film resist 50 is disposed on the entire one surface 21 of metal substrate 2, and then, as shown by the solid line, resist 5 having the same pattern as second portion 212 is formed from dry film resist 50 by photolithography. Note that dry film resist 50 may be either positive or negative.

[0058] As shown in FIG. 3D , in step (4), inorganic insulating portions 31 are formed by anodization at intervals in the surface direction on the first portion 211 (remaining portion) of one surface 21 of the metal substrate 2 exposed from the resist 5. Specifically, the metal substrate 2 provided with the resist 5 is used as the anode, and a carbon electrode is used as the cathode, and they are immersed in an electrolytic bath. Examples of the electrolytic bath include an aqueous solution of ammonium borate and an aqueous solution of sodium borate. The voltage in the anodization is, for example, 100 V to 2,000 V, and the current density in the anodization is, for example, 1 mA / cm. ２ ~100mA / cm ２ The temperature of the electrolytic bath is, for example, 25° C. to 95° C. The treatment time is, for example, 5 to 60 minutes.

[0059] During anodization, the first portion 211 of the one surface 21 moves (retreats) toward the other side in the thickness direction relative to the second portion 212. This is because the material of the first portion 211 exposed from the resist 5 dissolves into the electrolyte. At this time, the oxide layer 23 corresponding to the first portion 211 is removed, and further, one edge of the simple layer 24 corresponding to the first portion 211 is removed.

[0060] As a result, the inorganic insulating portion 31 is deposited on the first portion 211 .

[0061] In particular, when the metal substrate 2 contains aluminum, the anodization is called an alumite treatment.

[0062] 3E, in step (5), the resist 5 is removed. For example, the resist 5 is removed using a stripping solution. The stripping solution contains, for example, N-methyl-2-pyrrolidone (NMP).

[0063] Thereafter, the inorganic insulating portion 31 is heated as necessary. By heating the inorganic insulating portion 31, stress in the inorganic insulating layer 3 can be relieved in advance, and crack resistance after mounting can be further improved. The heating temperature is, for example, 150°C to 350°C. The heating time is, for example, 1 minute to 30 minutes.

[0064] 3F , in step (6), after step (5), the elastic insulating portion 32 is formed. In step (6), first, as shown by the imaginary lines, a photosensitive layer 320 is formed on the entire one surface of the inorganic insulating portion 31 and the second portion 212. Specifically, a photosensitive resin composition is placed on the one surface of the inorganic insulating portion 31 and the second portion 212. The resin composition contains a photosensitive component and the above-described resin and / or precursor.

[0065] Next, the elastic insulating portion 32 is formed by photolithography from the photosensitive layer 320. In this way, the mounting substrate 1 including the metal substrate 2 and the insulating layer 3 is manufactured.

[0066] As shown in FIG. 4 , the mounting substrate 1 may further include a wiring layer 4 in addition to the metal substrate 2 and the insulating layer 3. In this modification, the wiring layer 4 is disposed on one surface of the insulating layer 3 in the thickness direction. The wiring layer 4 has a patterned shape. The wiring layer 4 may be formed as a solid layer. For example, the wiring layer 4 is disposed on one surface 311 of two adjacent inorganic insulating portions 31 (31A, 31B) and on the surface (one surface in the thickness direction and the peripheral side surface) of the filling portion 321 between them. The wiring layer 4 extends along the surface direction. A plurality of wiring layers 4 are disposed at intervals from each other in a direction intersecting the extending direction. The wiring layer 4 is formed by a wiring formation method.

[0067] 4, the wiring layer 4 may be disposed on the other surface 22 of the metal substrate 2 in the thickness direction. The mounting substrate 1 may include the wiring layer 4 shown by both the virtual line and the solid line, or may include only the wiring layer 4 shown by the virtual line.

[0068] For example, a semiconductor element is mounted on one surface in the thickness direction of the mounting substrate 1. Electrodes (not shown) of the semiconductor element are electrically connected to the wiring layer 4.

[0069] 2, in this mounting substrate 1, the inorganic insulating portions 31 in the insulating layer 3 are spaced apart from one another in the surface direction. Therefore, even if stress is applied to one inorganic insulating portion 31A, stress is less likely to be applied to the inorganic insulating portion 31B adjacent to the one inorganic insulating portion 31A. Furthermore, because the inorganic insulating portions 31 can be made small, cracks are less likely to occur in the insulating layer 3.

[0070] Furthermore, the insulating layer 3 has elastic insulating portions 32 disposed between adjacent inorganic insulating portions 31. Therefore, the elastic insulating portions 32 can relieve the above-mentioned stress, thereby suppressing the occurrence of cracks in the insulating layer 3.

[0071] 3. Modifications In the modification, the same components and steps as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, the modification can achieve the same effects as those in the first embodiment unless otherwise specified. Furthermore, the first embodiment and its modification can be combined as appropriate.

[0072] Although not shown, the metal substrate 2 may not include the oxide layer 23 and may include only the simple substance layer 24 .

[0073] 2, the metal substrate 2 preferably includes an oxide layer 23. In one embodiment, since the metal substrate 2 includes the oxide layer 23, an inorganic insulating portion 31 having excellent insulating properties can be formed in the anodization in step (4).

[0074] Although not shown, the elastic insulating portion 32 does not necessarily have to include the bulge portion 322 .

[0075] Specific numerical values ​​such as blending ratios (content ratios), physical property values, and parameters used in the following description can be replaced with the upper limit values ​​(numerical values ​​defined as "not more than" or "less than") or lower limit values ​​(numerical values ​​defined as "not less than" or "exceeding") of the corresponding blending ratios (content ratios), physical property values, and parameters described in the above "Form for implementing the invention."

[0076] Example 1 Step (1): As shown in Fig. 3A, a metal substrate 2 was prepared, which had an aluminum plate as a single layer 24. The thickness of the metal substrate 2 was 150 µm.

[0077] As shown in Fig. 3B, the metal substrate 2 was heated in an air atmosphere at 550°C for 3 hours to form oxide layers 23 on one side and the other side of the simple substance layer 24 in the thickness direction. Each of the two oxide layers 23 had a thickness of 100 nm or less. The Young's modulus of the metal substrate 2 at 25°C was 69 GPa. The thickness T0 of the metal substrate 2 after heating was 150 µm.

[0078] Step (2) (Steps (3) to (6)): As shown in Fig. 3C, a negative dry film resist (Sunfort AQ, manufactured by Asahi Kasei Corporation) 50 was attached to one surface 21 of the metal substrate 2 by vacuum lamination (110°C, 0.4 MPa). A resist 5 having the same pattern as the second portion 212 was formed from the dry film resist 50 by photolithography (step (3)).

[0079] Anodization was carried out using a 0.5 M aqueous solution of sodium borate as an electrolytic bath, the metal substrate 2 on which the resist 5 was provided as an anode, and a carbon electrode as a cathode. The electrolytic bath temperature was set to 20°C, and a constant current density (2.5 mA / cm) was applied while stirring the electrolytic bath until the voltage reached 1000 V. ２ After the voltage reached 1000 V, the voltage was switched to a constant voltage treatment at 1000 V, and the anodization treatment was carried out for 1 minute. As a result, an inorganic insulating portion 31 was formed as shown in FIG. 3D (step (4)).

[0080] The size and Young's modulus of the inorganic insulating portion 31 were as follows: Thickness T1: 0.9 μm Minimum length L1 in the surface direction: 80 μm Young's modulus at 25° C.: 360 GPa

[0081] Thereafter, as shown in FIG. 3E, the resist 5 was peeled off (dissolved and removed) using NMP (step (5)).

[0082] Thereafter, the inorganic insulating portion 31 was heated at 300° C. for 30 minutes.

[0083] A photosensitive resin composition (negative type, manufactured by Nippon Kayaku Co., Ltd., permanent resist film SU-8) was applied by spin coating to one surface of the inorganic insulating portion 31 and the second portion 212 to form a 5 μm photosensitive layer 320. Next, the photosensitive layer 320 was heated on a hot plate at 95° C. for 4 minutes. Thereafter, the elastic insulating portion 32 was formed from the photosensitive layer 320 by photolithography. (Step (6))

[0084] The size and Young's modulus of the elastic insulating portion 32 are as follows: Thickness T2 of elastic insulating portion 32: 5 μm Thickness T21 of filling portion 321: 1 μm Thickness T22 of bulging portion 322: 4 μm Width W2 of elastic insulating portion 32 (= width W22 of bulging portion 322): 30 μm Width W21 of filling portion 321: 20 μm Young's modulus of elastic insulating portion 32 at 25° C.: 2.7 GPa

[0085] REFERENCE SIGNS LIST 1 Mounting substrate 2 Metal substrate 21 One side 3 Insulating layer 31, 31A, 31B Inorganic insulating portion 32 Elastic insulating portion 320 Photosensitive layer 4 Wiring layer 5 Resist

[0086] The above invention is provided as an exemplary embodiment of the present invention, but it is merely an example and should not be interpreted as being limiting. Modifications of the present invention that are obvious to those skilled in the art are intended to be included in the scope of the following claims.

[0087] The mounting board and the manufacturing method thereof of the present invention can be suitably used in various industrial fields where wired circuit boards are used.

Claims

1. A mounting board comprising: a metal substrate; and an insulating layer arranged on one side of the metal substrate in a thickness direction, the insulating layer having: a plurality of inorganic insulating portions arranged on a portion of the one side of the metal substrate and spaced apart from each other in a plane direction perpendicular to the thickness direction; and elastic insulating portions arranged on the remainder of the one side of the metal substrate and disposed between adjacent inorganic insulating portions.

2. The mounting board according to claim 1, further comprising a wiring layer disposed on one surface of the insulating layer in the thickness direction.

3. The mounting board according to claim 1, further comprising a wiring layer disposed on the other surface of the metal substrate in the thickness direction.

4. A method for manufacturing a mounting board as claimed in claim 1, comprising: a step (1) of preparing a metal substrate; and a step (2) of forming an insulating layer on one surface of the metal substrate in a thickness direction, the step (2) comprising: a step (3) of forming a resist on a portion of the one surface of the metal substrate in the thickness direction; a step (4) of forming inorganic insulating portions by anodization on the remaining portion of the one surface of the metal substrate exposed from the resist, the inorganic insulating portions being spaced apart from each other in a surface direction perpendicular to the thickness direction; and a step (5) of removing the resist.

5. The method for manufacturing a mounting board according to claim 4, wherein the step (2) comprises, after the step (5), a step (6) of applying a photosensitive resin composition to the inorganic insulating portion and one surface of the portion to form a photosensitive layer, and forming an elastic insulating portion from the photosensitive layer by photolithography.

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