JP6208869B2 - Metal substrate and panel for electronic device fabrication - Google Patents

Description

  The present invention relates to a metal substrate and panel for manufacturing an electronic device.

  A metal substrate having an insulating film on its surface is expected to be applied to electronic paper, organic EL displays, organic EL lighting, solar cell device substrates, and the like. In a solar cell substrate, heat resistance and insulation are important characteristics.

  In particular, in a compound semiconductor solar cell such as CIGS (CuInGaSe), the substrate is exposed to a temperature of 500 ° C. or higher in the heating step of the manufacturing process. Even if the metal substrate itself is exposed to the CIGS process temperature, characteristics such as weight, Young's modulus, and hardness do not change, but the insulating film covering the metal substrate has heat resistance to a heating temperature of 500 ° C. or more. Becomes important.

  In a solar cell, the voltage and current obtained from one cell are small, and it is necessary to connect a plurality of cells in series or in parallel. In the case of a solar cell substrate using a metal material, a method of forming cells directly on a metal substrate having an insulating film, cutting the entire substrate, and connecting the target cells to each other with a conductive wire, and an insulating film There is a method of manufacturing an integrated module by forming a cell by treating a metal substrate having the same as a glass substrate. The latter has high productivity because the module structure is simple, but if the insulation of the film is insufficient, the solar cell characteristics as designed cannot be obtained when a plurality of cells are connected. Therefore, it is important to produce a film free from defects such as pinholes.

In general, the leakage current is measured with the configuration shown in FIG. Reference numeral 101 denotes a steel material, 102 denotes an insulating film, 103 denotes an upper electrode, 104 denotes a voltmeter, 105 denotes an ammeter, and 106 denotes a power source.
Since there are film defects such as cracks in the insulating film 102, the leakage current often depends on the electrode area of the upper electrode 103. Therefore, the larger the electrode area, the higher the leak current and the more likely to be short-circuited. In addition, the higher the applied voltage, the higher the voltage applied to the thin film portion, which is a film defect, and a short circuit tends to occur.

In order to fabricate an integrated device, a large area has a low leakage current when a high voltage is applied, for example, 1 × 10 ⁻⁶ A / cm ² or less when a 50 V is applied at a 10 × 10 cm square, and 1 × 10 ⁶ when a 200 V is applied at a 1 × 1 cm square. ^-8 A / cm ² or less is required. The required area and leakage current vary depending on the device to be manufactured, but one general index is that it is less than 1 × 10 ⁻⁶ A / cm ² when applying 100 V at a 3 × 3 cm square.

  Patent Document 1 discloses a stainless steel foil coated with an inorganic-organic hybrid having higher heat resistance than an organic resin. However, the coated stainless steel foil disclosed in Patent Document 1 has a problem that when the upper electrode is 1 × 1 cm square, application of a low voltage of about 10 V causes a short circuit at 100 V even if insulation is maintained. .

  Patent Document 2 discloses a stainless steel foil coated with a plurality of inorganic polymer films. However, in the stainless steel foil with a film disclosed in Patent Document 2, when the coating with the inorganic polymer film is formed on the stainless steel foil, the insulation is maintained by applying a low voltage of about 5 V when the upper electrode is 1 × 1 cm square. However, there is a problem that a short circuit occurs at 100V.

Non-Patent Document 1 describes that a methyl group-containing silica-based inorganic-organic hybrid film is used as an insulating film, but there is a problem in that cracks occur when the film thickness exceeds 1 μm. On the other hand, when the film thickness of the inorganic-organic hybrid film of Non-Patent Document 1 is 1 μm or less, it is difficult to make the leakage current when applying 100 V at 3 × 3 cm square to less than 1 × 10 ⁻⁶ A / cm ^2. .

Accordingly, the stainless steel foil having the coating disclosed in Patent Document 1, Patent Document 2 and Non-Patent Document 1 has a leakage current of less than 1 × 10 ⁻⁶ A / cm ² when 100 V is applied to the upper electrode 3 × 3 cm square. It is difficult to use as a metal substrate for manufacturing electronic devices.

  Patent Document 3 discloses a substrate for an electronic material having a surface insulating layer on a substrate such as aluminum or titanium. The substrate surface is anodized to form a film, and then a layer of a non-conductive substance is formed on the surface. To fill the pores of the anodized film.

However, Patent Document 3 does not teach a metal substrate for manufacturing an electronic device that satisfies a leakage current of less than 10 ⁻⁶ A / cm ² when 100 V is applied to an upper electrode 3 × 3 cm square.

  Patent Document 4 discloses a stainless steel foil with an insulating coating for solar cells, in which a two-layer insulating coating is formed on the stainless steel foil.

However, Patent Document 4 does not teach a metal substrate for producing an electronic device that satisfies a leakage current of less than 10 ⁻⁶ A / cm ² when a 100 V voltage is applied to an upper electrode 3 × 3 cm square.

Japanese Patent No. 3882008 Japanese Patent No. 4245394 Japanese Unexamined Patent Publication No. 11-229187 Japanese Unexamined Patent Publication No. 2013-89697

N. Yamada, T. Ogura, S. Ito and Y. Kubo, “Surface Morphology and Reliability Evaluation of Insulating Films on Stainless Steel Foil,” Proc. IDW’09, pp. 775-778 (2009)

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a metal substrate and a panel excellent in insulation that can be suitably used for manufacturing an electronic device.

The gist of the present invention for achieving the above object is as follows.
(1) In the first aspect of the present invention, the Al content is 0.5 to 13.0 mass%, the Si content is 0 to 5.0 mass%, and the total content of the Al and the Si is included. A steel material having an amount of 0.5 to 18.0% by mass, and wherein the Si content in the steel material is ½ or less of the Al content ; covering the surface of the steel material, and having a thickness of 0.2 μm A first insulating film having a thickness of ~ 2.0 μm; a second insulating film having a thickness of 0.3 μm to 5.0 μm, covering the surface of the first insulating film; The total thickness of the first insulating film and the second insulating film is 2.0 μm to 7.0 μm, and the first insulating film is at least one of Al ₂ O ₃ and SiO ₂ . together contain a thermal oxide film containing spinel minerals, in the first insulating film, the spinel mineral The Al ₂ O ₃ exists weight of less than 3% to 11% by mass% ratio, the second insulating film is formed from a silica-based inorganic-organic hybrid materials, organic of the silica-based inorganic-organic hybrid materials group is an electronic device fabrication metal substrate Ru methyl or phenyl der.
( 2 ) In the metal substrate for manufacturing an electronic device according to ( 1 ), in the first insulating film, the Al ₂ O ₃ covers the surface of the steel material, and the spinel mineral is the steel material of the steel material. The structure which does not coat | cover the surface directly may be sufficient.
(3) In the second aspect of the present invention, the Al content is 0 to 13.0 mass%, the Si content is 0.5 to 5.0 mass%, and the Ca content is 0.0001 to Steel material that is 0.1% by mass, the total content of Al and Si is 0.5 to 18.0% by mass, and the Al content in the steel material is ½ or less of the Si content Covering the surface of the steel material with a thickness of 0.2 μm to 2.0 μm; covering the surface of the first insulating film with a thickness of 0.3 μm to A second insulating film having a thickness of 5.0 μm, wherein a total thickness of the first insulating film and the second insulating film is 2.0 μm to 7.0 μm, The insulating film is a thermal oxide film containing at least one of Al ₂ O ₃ and SiO ₂ and containing an olivine mineral. In the first insulating film, the ratio of the sum of the number of moles of Mg, Fe, and Ca to the number of moles of Si is 1.2 or more and 2.0 or less, and the second insulating film is formed of silica. It is a metal substrate for producing an electronic device, which is formed from an inorganic inorganic organic hybrid material, and the organic group of the silica inorganic organic hybrid material is a methyl group or a phenyl group.
( 4 ) In the metal substrate for manufacturing an electronic device according to ( 3 ), in the first insulating film, the SiO ₂ covers the surface of the steel material, and the olivine mineral covers the surface of the steel material. The structure which does not coat | cover directly may be sufficient.
( 5 ) In the metal substrate for manufacturing an electronic device according to any one of (1) to ( 4 ), the surface roughness Ra measured in a 1 μm square region of the second insulating film is less than 2 nm. There may be.
( 6 ) In the metal substrate for manufacturing an electronic device according to any one of (1) to ( 5 ), the steel material contains 19% by mass or more of Cr and has a thickness of 150 μm or less. It may be .
( 7 ) A third aspect of the present invention is a panel in which an electronic device is formed on the metal substrate for manufacturing an electronic device according to any one of (1) to ( 6 ).

  According to the said aspect of this invention, the metal substrate and panel excellent in the insulation which can be used suitably for manufacture of an electronic device can be provided.

It is a schematic diagram explaining a CIGS solar cell. It is a schematic explanatory drawing in the case of forming a first insulating film and a second insulating film on a steel material. It is a schematic explanatory drawing in the case of forming only the first insulating film on a steel material. It is a schematic explanatory drawing in the case of forming only a second insulating film on a steel material. It is a schematic explanatory drawing of the metal substrate for electronic device manufacture which concerns on this embodiment. It is a SEM photograph which shows the cross-sectional structure of steel materials, a 1st insulating film, and a 2nd insulating film. It is a STEM image which shows the cross-sectional structure of the steel material and the 1st insulating film formed in the steel material surface. In the first insulating film is a graph showing the abundance of the mass% ratio _Al 2 _{O 3} spinel mineral, the relationship between the leakage current (A / cm ²⁾ and the surface roughness Ra (nm). The graph which shows the relationship between the ratio of the sum of the number of moles of Mg, Fe, and Ca with respect to the number of moles of Si, the leakage current (A / cm ² ), and the surface roughness Ra (nm) in the first insulating film. It is. It is a schematic diagram of a leak current measuring device.

  The metal substrate can be used to produce an electronic device thereon to obtain an electronic device mounting panel. As an example of such an electronic device mounting panel, electronic paper, an organic EL display, organic EL illumination, a solar cell, etc. are mentioned. All of these panels are well known and will not be described in detail here.

As an example, a solar cell (CIGS solar cell) using a CIGS (CuInGaSe ₂ ) compound semiconductor will be briefly described. FIG. 1 shows an example of a typical structure. In FIG. 1, 141 is a substrate, 142 is a back electrode (lower electrode) such as Mo, 143 is a CuInGeSe ₂ light absorption layer, 144 is a CdS buffer layer, 145 is a ZnO semi-insulating layer, 146 is a ZnO: Al window layer, 147 Is an Al upper electrode, and 148 is a MgF ₂ antireflection film. Examples of film thickness are 0.8 μm, 1.7 μm, 50 nm, 0.1 μm, and 0.6 μm in order from the back electrode 142 to the ZnO: Al window layer 146. As the substrate 141, a steel plate or stainless foil provided with an insulating film such as a methyl group-containing silica-based inorganic organic hybrid film can be used.

In developing a new metal substrate that can be suitably used for manufacturing electronic devices, the present inventors conducted experiments in which various steel materials were heat-treated at high temperatures to form oxide films (thermal oxide films) on the surface. .
As a result, as shown in FIG. 2A, a thermal oxide film 1011 mainly composed of Al ₂ O ₃ is formed on the surface of the stainless steel foil 1010 by heat-treating the stainless steel foil 1010 containing about 5% of Al under predetermined conditions. Furthermore, it has been found that when the silica-based inorganic organic hybrid film 1012 is formed on the thermal oxide film 1011, the leakage current characteristics of the substrate are remarkably improved. For this phenomenon, a stainless steel foil containing about 2.5% of Si is heat-treated under predetermined conditions to form a thermal oxide film mainly composed of SiO ₂ on the surface of the stainless steel foil. It was also confirmed when a silica-based inorganic-organic hybrid film was formed on the film.

On the other hand, as shown in FIG. 2B, when only the thermal oxide film 1011 is formed on the surface of the stainless steel foil 1010 and the silica-based inorganic organic hybrid film 1012 is not formed, the thermal oxide film 1011 can be made thicker. No significant improvement in leakage current characteristics was observed. Similarly, as shown in FIG. 2C, when only the silica-based inorganic organic hybrid film 1012 is formed on the surface of the stainless steel foil 1010 and the thermal oxide film 1011 is not formed, the film thickness of the silica-based inorganic organic hybrid film 1012 is reduced. Even when it was increased, no significant improvement in leakage current characteristics was observed. That is, it was found that the leakage current characteristics were particularly improved by combining the thermal oxide film 1011 and the silica-based inorganic / organic hybrid film 1012.
Furthermore, when the experiment was conducted by replacing the stainless steel foil with a steel plate, the same result was obtained.

The reason why the leakage current characteristics are particularly improved by combining the thermal oxide film 1011 and the silica-based inorganic / organic hybrid film 1012 is considered as follows.
In other words, in order to increase insulation,
(1) Increasing the film thickness of the thermal oxide film 1011 (2) Increasing the film thickness of the silica-based inorganic-organic hybrid film 1012 can be considered, but (1) When increasing the film thickness of the thermal oxide film 1011, Since the thermal oxide film 1011 is an inorganic film, cracks C are likely to occur as shown in FIG. 2B, and there is a limit to the effect of improving insulation by increasing the film thickness. Further, (2) even if the film thickness of the silica-based inorganic / organic hybrid film 1012 is increased, as shown in FIG. 2C, the coating liquid flows, so that the film thickness of the concave portion on the surface of the stainless steel foil 1010 is large. The film thickness of the portion becomes small, and in some cases, sharp protrusions present on the surface of the stainless steel foil 1010 appear on the outermost layer. In this case, a region where the surface of the stainless steel foil 1010 cannot be formed is formed in a pinhole shape, resulting in poor insulation. Furthermore, if the film thickness of the silica-based inorganic organic hybrid film 1012 is too large, the film-forming component is thermally decomposed when the substrate is exposed to a temperature of 500 ° C. or higher in the heating step of the electronic device manufacturing process, Since gas is generated, the characteristics of the electronic device are adversely affected.

  Therefore, in the present invention, by forming the thermal oxide film as the first insulating film, an area that cannot be formed into a pinhole is prevented, and an insulating film made of a silica-based inorganic-organic hybrid material is formed thereon. The basic idea is to exhibit high insulation by forming as a second insulating film.

  Furthermore, the present inventors have also found that when a predetermined amount of spinel mineral or olivine mineral is contained in the thermal oxide film, even higher insulation can be exhibited.

  Hereinafter, the present invention based on the above-mentioned new knowledge will be described in detail with reference to the drawings based on the embodiments.

(Configuration of metal substrate 1)
As shown in FIG. 3, the metal substrate 1 for manufacturing an electronic device according to the present embodiment includes a steel material 10, a first insulating film 11 that covers the surface of the steel material 10, and the first insulating film. 11 and a second insulating film 12 covering the surface of 11.

(Configuration of steel 10)
As the steel material 10, a stainless steel foil, a steel plate, or the like can be used. Since the steel material 10 is used as a base material of the metal substrate 1 for producing an electronic device, it only needs to have a thickness of 50 to 500 μm. In the present invention, the stainless steel foil means a foil material having a Cr content of 19% by mass or more and a thickness of 150 μm or less.

In the metal substrate 1 for manufacturing an electronic device according to the present embodiment, fine protrusions on the surface of the steel material 10 are covered with a first insulating film 11 containing Al ₂ O ₃ and / or SiO ₂ , and the surface is further covered. By forming the second insulating film 12, the surface roughness can be reduced and high insulation can be obtained. Since Al ₂ O ₃ or SiO ₂ contained in the first insulating film 11 is obtained by heat treatment of the steel material 10 containing Al or Si, the Al content and the Si content in the steel material 10 are in a predetermined range. It is necessary to stipulate. Hereinafter, unless otherwise specified, “%” related to chemical components means “% by mass”.

Al + Si: 0.5 to 18.0%
Al: 0 to 13.0%
Si: 0 to 5.0%
When the total amount of Al and Si in the steel material 10 is less than 0.5%, an oxide scale (Fe ₂ O ₃ , Fe ₃ O ₄ ) is generated by the heat treatment, and thus Al ₂ O ₃ and / or SiO ₂ is included. It becomes difficult to form the first insulating film 11 with a predetermined thickness. In other words, if the total amount of Al and Si in the steel material 10 is 0.5% or more, Al and / or Si having a stronger affinity for oxygen than Fe is preferentially oxidized by heat treatment, so Al and / or Si can be sufficiently supplied to the first insulating film 11. Thus, it is possible to form a first insulating film 11 containing _Al 2 _{O 3} and / or SiO ₂ at a predetermined thickness. Therefore, the lower limit of the total content of Al and Si is 0.5%, more preferably 0.7%, and still more preferably 1.2%.
In the metal substrate 1 for producing an electronic device according to the present embodiment, at least one of Al ₂ O ₃ and SiO ₂ only needs to be included in the first insulating film 11, and therefore each of Al and Si in the steel material 10. The lower limit may be 0%. However, since Si and Al are used as a deoxidizer during steelmaking, the lower limit of each may be 0.001%.
On the other hand, when the Al content of the steel material 10 exceeds 13.0%, an intermetallic compound is generated between the steel material 10 and the first insulating film 11 to cause embrittlement. Therefore, the upper limit of the Al content in the steel material 10 is 13.0%, preferably 10.0%, and more preferably 8.0%.
Moreover, when Si content of the steel material 10 exceeds 5.0%, the hardness of the steel material 10 will raise remarkably and productivity will be impaired. Therefore, the upper limit of the Si content is 5.0%, preferably 3.0%, and more preferably 1.5%.
The upper limit of Al + Si is 18.0 mass, which is the sum of the upper limits.

The chemical components other than Al and Si in the steel material 10 do not have to be specifically limited in order to achieve the effects of the present invention, and may be chemical components and content ratios used in general steel materials. Among the basic five elements of steel, the contents generally used for the four elements other than Si are as follows.
C: 0.0005 to 1.0%
Mn: 0.01 to 2.0%
P: 0.001 to 0.02%
S: 0.001 to 0.02%

The steel material 10 may contain Mg, Cr, and Ca in the following ranges.
Mg: 0 to 1.5%
Cr: 0 to 25%
Ca: 0 to 0.1%

The Mg content in the steel material 10 may be 0% by mass.
However, since the steel material 10 contains Al and / or Si, MgAl ₂ O ₄ or olivine mineral, which is a spinel mineral, is contained in the first insulating coating 11 by a predetermined heat treatment by containing Mg in the steel material 10. It becomes possible to produce a certain Mg ₂ SiO ₄ . As will be described later, by containing a predetermined amount of spinel mineral or olivine mineral in the first insulating film 11, it becomes possible to obtain further higher insulation, so Mg content is 0.1% or more It is preferable to contain 0.2% or more.
On the other hand, if the Mg content of the steel material 10 is excessively increased, the workability of the steel material 10 is lowered, so the upper limit is preferably 1.5% or less, and more preferably 1.2% or less.
As will be described later, by applying Mg slurry to the surface of the steel material, the amount of Mg taken into the first insulating film can be increased.

The Cr content in the steel material 10 may be 0% by mass.
However, if the steel material 10 contains Al, by incorporating the Cr steel material 10, it makes it possible to produce a CrAl ₂ O ₄ spinel mineral into the first insulating film 11 by a predetermined heat treatment . As will be described later, by including a predetermined amount of spinel mineral in the first insulating film 11, it becomes possible to obtain a much higher insulating property. For this reason, the Cr content is preferably 0.1% or more, and more preferably 0.2% or more.
Since the steel material 10 in this invention can use a stainless steel material, it is good also considering the upper limit as about 25%.

The Ca content in the steel material 10 may be 0% by mass.
However, if the steel material 10 containing Si, by incorporating the Ca in steel 10, it is possible to produce a Ca ₂ SiO ₄ which is olivine mineral in the first insulating film 11 by a predetermined heat treatment . As will be described later, by containing a predetermined amount of olivine mineral in the first insulating film 11, it becomes possible to obtain a much higher insulating property, so that the Ca content is 0.0001% or more. Preferably, it is more preferably 0.0005% or more.
However, even if Ca exceeds 0.1%, the above effect is not changed, so the upper limit is made 0.1%.

The component composition of the steel material 10 may contain Ni, Mo, W, Cu, V, B, Ta, Nb, Y, Zr, Ti, and the like often used for alloy steel, in addition to the above-described elements. Further, the balance may be Fe and inevitable impurities.
Since the steel material 10 contains Fe and Al and / or Si, the spinel mineral FeAl ₂ O ₄ or the olivine mineral Mg ₂ SiO ₄ is generated in the first insulating film 11 by a predetermined heat treatment. I can do it.

(Configuration of the first insulating film and the second insulating film)
The first insulating film 11 covering the surface of the steel material 10 is a thermal oxide film containing Al ₂ O ₃ or SiO ₂ . This thermal oxide film is obtained by heat-treating the steel material 10 containing Al and / or Si under predetermined conditions, so that Al or Si on the surface of the steel material 10 is more stable with Al ₂ O ₃ or SiO ₂ . It is obtained by doing.
The heat treatment conditions are not particularly limited as long as the desired thermal oxide film is obtained. In addition, the apparatus which heat-processes is not specifically limited, The arbitrary apparatuses which can heat the steel material 10 to be processed to predetermined temperature in predetermined atmosphere can be utilized.
The thickness of the first insulating film 11 greatly depends on the heating temperature and the heating time during the heat treatment, and also depends on the Al concentration, the Si concentration, etc. in the steel material.

  As a first example, when using a stainless steel foil having a thickness of 100 μm and containing about 5% of Al as the steel material 10, the stainless steel foil is subjected to a heat treatment for 1 hour at a temperature of 900 ° C. to 1200 ° C. in the atmosphere. The first insulating film 11 having a thickness of about 0.4 to 1.4 μm can be formed on the surface of the stainless steel foil.

  As a second example, when a steel plate having a thickness of 300 μm and containing about 10% Al is used as the steel material 10, the steel plate is subjected to a heat treatment for 6 hours at a temperature of 900 ° C. to 1200 ° C. in the atmosphere. The first insulating film 11 having a thickness of about 0.3 to 0.7 μm can be formed on the surface.

  As a third example, when a stainless steel foil having a thickness of 100 μm containing about 2.5% Si is used as the steel material 10, the stainless steel foil is inert such as nitrogen adjusted to a dew point of 30 ° C. to 50 ° C. The first insulating film 11 having a thickness of about 0.5 to 0.9 μm can be formed on the surface of the stainless steel foil by subjecting it to a heat treatment for 1 hour at a temperature of 900 to 1100 ° C. in a gas.

  As a fourth example, when using a steel plate 10 having a thickness of 300 μm and containing about 5% of Si as the steel material 10, the steel plate is 750 ° C. in an inert or reducing gas atmosphere adjusted to a dew point of 30 ° C. to 50 ° C. By subjecting it to a heat treatment for 1 hour at a temperature of ˜900 ° C., the first insulating film 11 having a thickness of about 0.5 to 1.5 μm can be formed on the surface of the steel sheet.

  In addition, when adding the water | moisture content as an oxygen source in process atmosphere, the inert gas or reducing gas which adjusted the dew point can be used.

The first insulating film 11 exhibits an electric resistivity of 10 ⁹ Ωcm or more, which is necessary as a characteristic of the insulating film. The electrical resistivity is measured at room temperature (20 ° C.) by providing circular electrodes on the top and bottom of the inorganic oxide sheet according to JIS K 6911 (2006), and 500 V is applied between the electrodes to insulate the resistance value after 1 minute. Measure with an ohmmeter. A film made of Al ₂ O ₃ or SiO ₂ has an electric resistivity of 10 ⁹ Ωcm or more. When the electrical resistance is smaller than this, it functions as a semiconductor and flows electricity, so it is not suitable for use as an insulating film material. The electrical resistivity of the first insulating film 11 is preferably 10 ¹⁰ Ωcm or more, more preferably 10 ¹² Ωcm or more. As described above, when the total amount of Al and Si in the steel material 10 is less than 0.5%, the oxide scale by heat treatment, i.e. _{Fe 2 O 3, Fe 3 O} 4 occurs but, Fe ₂ The electrical resistivity of O ₃ and Fe ₃ O ₄ is not sufficient, and it becomes difficult to achieve an electrical resistivity of 10 ⁹ Ωcm or more. Therefore, it is important that the component of the first insulating film 11 is Al ₂ O ₃ and / or SiO ₂ capable of realizing a sufficient electrical resistivity of 10 ⁹ Ωcm or more.

By forming the first insulating film 11 as described above, the surface can be coated with a uniform thickness regardless of the irregular shape of the steel material 10. However, since the insulating property as the electronic device manufacturing metal substrate 1 cannot be ensured only by the first insulating coating 11, the surface of the first insulating coating 11 has a high insulating silica. A second insulating film 12 formed from the organic inorganic / organic hybrid material is formed. The second insulating film is combined with the first insulating film to enhance the insulating properties and to reduce the surface roughness of the steel material.
As an example, a thermal oxide film (first insulating film 11) containing Al ₂ O ₃ is formed on the surface of a steel material (steel material 10) containing 5% Al in FIG. The SEM photograph of the structure in which the membrane | film | coat (2nd insulating membrane | film | coat 12) formed from a system inorganic organic hybrid material was formed is shown.

The second insulating film 12 is formed from a silica-based inorganic / organic hybrid material. Preferably, the organic group of the silica-based inorganic organic hybrid material is a methyl group or a phenyl group.
The method for forming the second insulating film 12 is not particularly limited, and may be appropriately selected depending on the material to be used. Examples of the insulating film forming method that can be used include a coating method, a sputtering method, a printing method, a CVD method, and a sol-gel method.

The silica-based inorganic / organic hybrid material is, for example, a methyl group-containing silica-based inorganic / organic hybrid material. The methyl group-containing silica-based inorganic organic hybrid material is a material having a siloxane skeleton modified with a methyl group, and has the following formula A,
(SiO ₂ ) _x- (CH ₃ SiO _3/2 ) _(1-x) Formula A
(In formula A, 0 <x <1.0).
The smaller the x in Formula A, the more the amount of methyl groups, and the more flexible the film, but the heat resistance tends to decrease. A preferable range of x is 0.2 ≦ x ≦ 0.8, and further 0.4 ≦ x ≦ 0.6.

  The second insulating film 12 made of a methyl group-containing silica-based inorganic / organic hybrid material can be produced by a sol-gel method. The manufacturing method will be described. At least one selected from tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane, and at least one selected from methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, and methyltributoxysilane. More than one kind of silane is mixed and hydrolyzed in an organic solvent. As the organic solvent, methanol, ethanol, propanol, butanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, MEK, MIBK, or the like can be used alone or in combination. It is desirable that the water used for the hydrolysis is 0.3 mol to 3 mol times the total alkoxy groups. At the time of hydrolysis, a metal alkoxide catalyst other than silicon, an organic acid, or an inorganic acid may be used. The sol coating solution thus prepared is applied onto the first insulating film 11 formed in advance on the surface of the steel material 10. For coating, methods such as spin coating, dip coating, and roll coating can be used. After coating, after drying for 0.5 to 5 minutes at about 80 to 150 ° C., heat treatment is performed at 400 to 600 ° C. in an inert gas such as nitrogen for 0.5 to 10 hours, whereby a methyl group-containing silica-based inorganic organic hybrid The second insulating film 12 made of the material can be obtained.

The thickness of the second insulating film 12 is such that the leakage current of the steel material 10 is less than 1 × 10 ⁻⁶ A / cm ² when 100 V is applied at 3 × 3 cm square so as to be suitable for manufacturing an electronic device. It is preferable that For example, when the second insulating film 12 having a thickness of 1 μm is formed on the first insulating film 11 having a thickness of 0.7 μm with a methyl group-containing silica-based inorganic / organic hybrid material, the leakage current of the metal substrate 1 is It becomes about 1 × 10 ⁻⁹ A / cm ² . Leakage current depends not only on the thickness of the first insulating film 11 and the second insulating film 12 but also on the type of material thereof, but generally speaking, the second insulating film 12 If it is formed within the range of 0.3 to 5 μm, the above-mentioned leakage current requirement can be satisfied.

  The second insulating film 12 preferably has a surface roughness Ra of less than 2 nm measured in an area of 1 μm square using an atomic force microscope (AFM). By satisfying this condition, even if it is a structure of an organic EL light emitting device or an organic thin film solar cell device in which a thin layer of 10 to 150 nm is laminated, it can be covered with a thin layer without interruption, so that the device performance is enhanced. be able to.

Hereinafter, the film thicknesses of the first insulating film 11 and the second insulating film 12 will be described.
In order to function as a substrate for manufacturing an electronic device, as a premise, the substrate and the electronic device must be electrically cut off by 2.0 μm or more. Therefore, the first insulating film 11 and the second insulating film 12 are formed so that the total film thickness becomes 2.0 μm or more. The upper limit value of the total film thickness is a total value of 7.0 μm including the upper limit value of the film thickness of the first insulating film 11 and the upper limit value of the film thickness of the second insulating film 12 described below.

The first insulating film 11 has a thickness of 0.2 μm or more, preferably 0.3 μm or more, more preferably 0.5 μm or more. When the thickness of the first insulating film 11 is smaller than 0.2 μm, the effect of covering the surface of the steel material 10 cannot be sufficiently obtained. As a result, even if the second insulating film 12 is formed, the coating of the steel convex portion becomes insufficient, and excellent insulating properties cannot be obtained. In other words, by setting the thickness of the first insulating film 11 to 0.2 μm or more, the steel material 10 and the second insulating film 12 can be reliably separated so as not to contact each other. Insulation can be improved. Only the second insulating film 12 causes fine protrusions on the surface of the steel material 10 to appear on the outermost surface, so that pinholes and repellency occur, and good insulation cannot be obtained.
On the other hand, even if the thickness of the first insulating film 11 exceeds 2.0 μm, not only the above-described effect is saturated, but also by the cooling step in the heat treatment process when the first insulating film 11 is formed, Warpage due to a difference in thermal expansion coefficient between the oxide and the steel material occurs in the steel material. If the substrate is warped, the electronic device characteristics vary greatly or cannot function as a device. Therefore, the upper limit is set to 2.0 μm.

The second insulating film 12 has a thickness of 0.3 μm or more, preferably 0.6 μm or more, and more preferably 0.8 μm or more. If the thickness of the second insulating film is less than 0.3 μm, the effect of supplementing the insulating property of the first insulating film 11 cannot be obtained.
On the other hand, when the thickness of the second insulating film 12 exceeds 5.0 μm, the volatilization amount when exposed to the manufacturing process temperature (500 ° C. or higher) of the electronic device cannot be ignored. Degassing from the substrate adversely affects the characteristics of the electronic device as an impurity. Therefore, the upper limit of the thickness of the second insulating film 12 is 5.0 μm, preferably 3.0 μm, and more preferably 2.0 μm.

When the first insulating film 11 contains Al ₂ O ₃ , it is preferable to further contain a spinel mineral. By containing spinel mineral, it is possible to suppress the coarsening of the _Al 2 _{O 3} particles, _Al 2 _{O 3} particles having a uniform size of about 0.2~0.7μm is easily generated. That is, the deterioration of the surface roughness due to the coarsened Al ₂ O ₃ can be suppressed. Therefore, the surface roughness can be reduced.
When a large amount of coarsened Al ₂ O ₃ is produced, roughened Al ₂ O ₃ irregularities appear on the surface of the second insulating film, and the surface roughness is reduced. The device characteristics formed on the insulating film are deteriorated. In particular, in the case of a device in which thin films are laminated, such as an organic EL element or an organic thin film solar cell, if the surface of the substrate is rough, the laminated structure is disturbed, so that the device cannot function.
Examples of the spinel mineral include MgAl ₂ O ₄ , FeAl ₂ O ₄ , Fe (Al, Cr) ₂ O _{4 and the} like.

More specifically, in the first insulating film 11, the amount of the spinel mineral with respect to Al ₂ O ₃ is 3% or more, preferably 5% or more in terms of mass%, so that the above effect can be suitably achieved. Can be obtained.
On the other hand, in the first insulating film 11, when the abundance of the spinel mineral with respect to Al ₂ O ₃ is more than 11% by mass ratio, voids increase at the grain boundary between the spinel mineral and Al ₂ O _3. . As a result, the mechanical strength of the first insulating film 11 becomes insufficient and peeling or the like occurs, so that the insulating property may be impaired. Accordingly, the abundance of the spinel mineral with respect to Al ₂ O ₃ is preferably 11% or less, and more preferably 9% or less, in terms of mass ratio.

In order for the first insulating film 11 to contain Al ₂ O ₃ and a spinel mineral, the steel material 10 needs to contain an Al content of 0.5 mass% or more. Moreover, it is preferable that Si content shall be 1/2 or less of Al content.
Then, for this steel, by performing heat treatment in the range of 900 ° C. to 1200 ° C., the abundance relative to _Al 2 _{O 3} spinel minerals in the first insulating film 11, 3% or more 11% by mass% ratio It can be as follows. The abundance of the spinel mineral with respect to Al ₂ O ₃ greatly depends on the heat treatment atmosphere. For example, when heat treatment is performed on the same steel material under the same heat treatment conditions other than the heat treatment atmosphere, the higher the oxygen partial pressure, the lower the abundance of spinel mineral in the first insulating film with respect to Al ₂ O ₃ . It becomes possible. Al is distributed corundum with spinel when oxidized, but the higher the oxygen partial pressure, the higher the distribution coefficient to corundum. This is presumably because corundum having a crystallographically dense structure is more stable under a high oxygen partial pressure. In addition, when Al ₂ O ₃ and a spinel mineral are both contained in the first insulating film 11 by such heat treatment, the Al ₂ O ₃ coats the surface of the steel material, and the spinel mineral is directly applied to the surface of the steel material. It can be set as the structure which is not coat | covered. FIG. 5 shows an insulating film 11 having an Al ₂ O ₃ layer 11a formed so as to cover the surface layer of the steel material 10 and a layer 11b containing a spinel mineral formed so as to cover the Al ₂ O ₃ layer 11a. A cross-sectional STEM image is shown. According to this structure, the steel surface is coated with _{the Al} 2 _{O 3} layer 11a, for further coated with a layer 11b comprising a spinel mineral _{the Al} 2 _{O 3} layer 11a, it is possible to improve the insulation .

  The structure of the first insulating film can be observed, for example, by scanning electron microscopy and composition analysis.

When the steel material 10 on which the first insulating film 11 is formed is analyzed by a thin film X-ray diffractometer using Cu-Kα rays, 2θ = 25.58 °, 35.15 °, 52.55 °, 57 Corundum structure Al ₂ O ₃ showing a diffraction peak at .50 ° and spinel showing diffraction peaks at 2θ = 19.03 °, 31.27 °, 36.85 °, 44.83 °, etc. are detected. . From the ratio (Is / Ic) of the diffraction intensity of 2θ = 36.85 ° (Is), which is the main peak of spinel, to the diffraction intensity (Ic) of 2θ = 35.15 °, which is the main peak of corundum, to Al ₂ O ₃ You can know the abundance of spinel minerals.

Also, if the first insulating film contains SiO _2, preferably further contains an olivine mineral. Since the olivine mineral is excellent in adhesiveness with the steel material 10 and has high insulation, the inclusion of the olivine mineral contributes to the improvement of the characteristics of the first insulating film 11.
By containing the olivine mineral, it is possible to increase the ratio of the olivine mineral to the amorphous SiO ₂ and obtain sufficient adhesion. By increasing the adhesion, it is possible to suppress the occurrence of cracks and peeling due to the difference in thermal expansion coefficient, and it is possible to obtain better insulating properties.
Examples of olivine minerals include Mg ₂ SiO ₄ , Fe ₂ SiO ₄ , Ca ₂ SiO _{4 and the} like.

More specifically, in the first insulating film, the ratio of the sum of the number of moles of Mg, Fe, and Ca to the number of moles of Si is 1.2 or more, more preferably 1.4 or more. The effect of can be obtained.
On the other hand, in the first insulating film, when the ratio of the sum of the number of moles of Mg, Fe, and Ca to the number of moles of Si exceeds 2.0, in addition to the olivine mineral, Mg, Fe, and Ca There will be oxides, and these oxides may roughen the surface. Therefore, in the first insulating film, the ratio of the sum of the number of moles of Mg, Fe, and Ca to the number of moles of Si is preferably 2.0 or less, and more preferably 1.8 or less. .

In order to contain the SiO ₂ and the olivine mineral in the first insulating film 11, the steel material 10 needs to contain Si content of 0.5 mass% or more. Moreover, it is preferable that Al content shall be 1/2 or less of Si content.
And by heat-processing with respect to this steel material in the range of 900 degreeC-1200 degreeC, ratio of the sum of the mole number of Mg, Fe, and Ca with respect to the mole number of Si in a 1st insulating film is 1.2. It can be set to 2.0 or less.
Moreover, the ratio of the sum of the number of moles of Mg, Fe, and Ca to the number of moles of Si in the first insulating film is also adjusted by applying MgO slurry to the surface of the steel material before heat treatment, as will be described later. I can do it.
In the case where both the SiO ₂ and the olivine mineral are contained in the first insulating film 11 by such a heat treatment, the SiO ₂ covers the surface of the steel material, and the olivine mineral does not directly cover the surface of the steel material. Therefore, excellent insulating properties can be obtained.

  The steel material 10 on which the first insulating film 11 is formed is subjected to elemental analysis with an energy dispersive X-ray analyzer (EDS) to obtain the atomic percentage of each element present. Since the ratio of the number of atoms is a molar ratio, the ratio of the sum M (M + F + C) of the number of moles of Mg, Fe, and Ca to the number of moles M (S) of Si, that is, M (M + F + C) / M (S) is obtained. be able to.

In the first insulating film 11, MgAl ₂ O ₄ is particularly effective as a spinel mineral, and Mg ₂ SiO ₄ is particularly effective as an olivine mineral.
However, the amount of Mg that can be contained in the steel material 10 is limited. Therefore, as a result of the inventors seeking to contain more Mg in the first insulating film 11, a slurry of magnesia (MgO) particles is applied to the surface of the steel material 10 prior to heat treatment. Was found to be effective.

Therefore, in order to make more MgAl ₂ O ₄ or Mg ₂ SiO ₄ exist in the first insulating film 11, a slurry of magnesia (MgO) particles is applied on the surface of the steel material 10 before heat treatment. It is preferable. As the magnesia particles, those having an average particle size of 0.5 to 3 μm, preferably about 0.8 to 2 μm can be used. The slurry can be prepared by dispersing magnesia particles in water or an organic solvent (such as various alcohols). The slurry concentration is preferably 20 to 80 wt%. When the amount is less than 20 wt%, a region where MgO is not applied is generated. If it exceeds 80 wt%, MgO agglomerates and locally coarse Mg ₂ SiO ₄ particles are formed, so that the smoothness of the steel material 10 after heat treatment becomes poor. The slurry concentration is preferably 25 to 70 wt%, more preferably 30 to 60 wt%. The slurry can be applied by a method usually used for slurry application, for example, roll coating or bar coating so as to obtain a coating film thickness of about 1 to 5 μm. It is not practical to apply the slurry to a thickness of less than 1 μm, and if the application thickness is less than 1 μm, the effect of using the slurry is reduced. When the coating thickness exceeds 5 μm, a large amount of unreacted MgO is washed away, and an effect commensurate with the cost cannot be obtained.

The purpose of causing MgAl ₂ O ₄ or Mg ₂ SiO ₄ to be present in the first insulating film 11 using the MgO slurry is not only to improve the insulation characteristics, but also to heat-treat in particular by winding a steel plate in a coil shape. Sometimes, the MgO slurry layer functions as a porous layer so that the atmospheric gas can easily reach the inside of the coil.

  Next, the present invention will be further described with reference to examples. It goes without saying that the invention is not limited to the embodiments presented here.

First, six types of steel materials A to E were prepared as steel materials for a metal substrate for producing an electronic device. Table 1 shows types, thicknesses (μm), main components (mass%), and surface roughness Ra (nm) of steel materials A to E.
The surface roughness Ra (nm) was measured based on JIS B 0601.
Steel materials A and B are Al-based steel materials in which the Al content is higher than the Si content.
The steel material C is a steel material (comparative example) with a small amount of Si + Al.
Steel materials D and E are Si-based steel materials in which the Si content is higher than the Al content.

Experiment No. As 1-12, 14 and 15, the 1st insulating film was formed by heat-processing with respect to the steel material A (stainless steel foil) on predetermined heat processing conditions.
Experiment No. No. 13, the first insulating film was formed by heat-treating the steel material A (stainless foil) coated with MgO slurry on the surface with a thickness of 1.0 μm under predetermined heat treatment conditions. Specifically, the MgO slurry is coated on the surface of the steel material A with a thickness of 1.0 μm by using a roll coater, which is obtained by dispersing MgO particles having an average particle diameter of 0.5 μm in water at 30 wt%. It was done by doing.

Experiment No. As 16-20, the 1st insulating film was formed by heat-processing with respect to the steel material B (steel plate) on predetermined heat processing conditions.
Experiment No. 21, the steel material C (steel plate) was heat-treated under predetermined heat treatment conditions.

Experiment No. As 22-36, the 1st insulating film was formed by heat-processing with respect to the steel material D (stainless steel foil) on predetermined heat processing conditions. Steel No. For Experiments 23-36, Experiment No. After the MgO slurry was applied in a predetermined thickness by the same method as in No. 13, heat treatment was performed.
Experiment No. As 37-41, the 1st insulating film was formed by heat-processing with respect to the steel materials E (steel plate) on predetermined heat processing conditions.

In Tables 2 and 3, Experiment No. Regarding 1-41, the steel materials used, heat treatment conditions, and the properties of the first insulating film are shown.
More specifically, the heat treatment conditions include a heat treatment atmosphere, a heating temperature (° C.), and a heating time (hr).

With respect to the heat treatment atmosphere, “DA” means dry air with a reduced water vapor content in the atmosphere and a dew point adjusted to −50 ° C. For example, DA / O ₂ = 80/20 means a mixed gas of dry air and oxygen having a volume ratio of 80:20.

The properties of the first insulating film in Tables 2 and 3 are the thickness (μm), the leakage current (A / cm ² ) after the formation of the first insulating film, and the spinel mineral Al ₂ O _3. The abundance (mass% ratio) with respect to or the ratio of the sum of the number of moles of Mg, Fe, and Ca to the number of moles of Si.

In order to obtain a leakage current (A / cm ² ) after forming the first insulating film, a 1 × 1 cm square Pt upper electrode is formed on the surface of the first insulating film using an ion coater, and a metal substrate The leakage current was measured by applying 100 V as the lower electrode.
A part of the surface thermal oxide film was shaved off for taking out the lower electrode. The value of the leak current is the minimum value of the leak current (A / cm ² ) obtained by measuring at 20 locations.

The abundance (mass% ratio) of the spinel mineral with respect to Al ₂ O ₃ was calculated by performing thin film XRD measurement using Cu—Kα rays on the first insulating film. More specifically, the spinel structure (MgAl ₂ O ₄ , FeAl ₂ O _4, Fe (Al, Cr) ₂ O) with respect to the diffraction intensity (Ic) of the peak attributed to the corundum structure (α-Al ₂ O ₃ ). ₄ and their solid solutions) and the like, based on the ratio (Is / Ic) of the diffraction intensity (Is) of the peaks attributed to them.
The ratio of the sum of the number of moles of Mg, Fe, and Ca to the number of moles of Si is present when the steel material with the first insulating film is subjected to elemental analysis with an energy dispersive X-ray analyzer (EDS). The atomic percentage of each element to be obtained was determined from the ratio of the sum M (M + F + C) of the number of moles of Mg, Fe and Ca to the number of moles M (S) of Si, that is, M (M + F + C) / M (S). .

Experiment No. 1-4, (A) phenyl group-containing silica film as the second insulating film after heat treatment,
Any one of (B) a polydimethylsiloxane-based film and (C) a methyl group-containing silica film was formed with a predetermined thickness. A specific forming method is shown below.

(A) Phenyl group-containing silica film After hydrolyzing phenyltriethoxysilane in ethanol with an equimolar amount of water with respect to all alkoxy groups using an acetic acid catalyst, a silica resin modified with a phenyl group by concentration with an evaporator is obtained. Produced. The resin was dissolved in toluene to prepare a coating solution for forming a phenyl group-containing silica film so that the viscosity was 10 mPa · s. After coating with a slit coater, heat treatment was performed at 400 ° C. for 5 minutes in nitrogen.

(B) Polydimethylsiloxane-based film 1 mol of silanol-terminated polydimethylsiloxane having a weight average molecular weight of 3,000 and 2 mol of titanium ethoxide are mixed in ethanol, hydrolyzed with 2 mol of water, and coated with a viscosity of 6 mPa · s. A liquid was prepared. After coating with a slit coater, heat treatment was performed in the atmosphere at 300 ° C. for 30 minutes.

(C) Methyl group-containing silica membrane Methyltriethoxysilane and tetramethoxysilane are added to 2-ethoxyethanol solvent at a molar ratio of 1: 1, and hydrolyzed with equimolar water to all alkoxy groups under an acetic acid catalyst. A sol was prepared. The viscosity of the obtained sol was 3.5 mPa · s. After coating with a slit coater, heat treatment was performed at 450 ° C. for 5 minutes in nitrogen.

In Tables 4 and 5, Experiment No. About 1-41, the property of the 2nd insulating film, surface roughness Ra (nm), film | membrane total thickness (micrometer), and the leakage current after 2nd insulating film formation are shown.
More specifically, the thickness (μm) and the type are shown as the properties of the second insulating film.
In addition, as a leakage current after forming the second insulating film, an average leakage current (A / cm ² ) and evaluation of the distribution of leakage current are shown.

The surface roughness Ra (nm) is a value measured with an AFM (Atomic Force Microscope) in a 1 × 1 μm square field of view.
The total film thickness (μm) is the total value of the thickness of the first insulating film and the thickness of the second insulating film.
The numerical value shown in the average (A / cm ² ) of the leakage current is the leakage current when 100 V is applied between the metal substrate and the upper electrode formed in the 1 cm × 1 cm region on the surface of the second insulating film. Is an average value of leakage current (A / cm ² ) obtained by measuring at 20 locations.
The distribution evaluation of the leakage current is carried out with respect to the leakage current obtained by measuring at the above 20 locations.
If the leakage current ≧ 1E-5 (A / cm ² ) is even one point, Bad,
If 1E-5 (A / cm ² )> leakage current ≧ 1E-8 (A / cm ² ) is at least one point,
If 1E-8 (A / cm ² )> leakage current at all measurement points, Good
It was evaluated.

  Experiment No. 2 to 11, 13, and 17 to 19, the steel material used and the production conditions are appropriate, the first insulating film having the spinel mineral is formed with an appropriate thickness, and the second insulating film is further appropriate. It was formed with various thicknesses. Therefore, the metal substrate excellent in the insulation which can be used suitably for manufacture of an electronic device was able to be obtained.

In particular, Experiment No. 2 to 11, the thickness of the first insulating film is 0.9 μm, the thickness of the second insulating film is constant at 3.6 μm, and the abundance of spinel mineral with respect to Al ₂ O ₃ (mass% ratio) ) Is dispersed in the range of 2.8 to 13.3. FIG. 6 shows the mass% ratio (horizontal axis) of the abundance of spinel mineral to Al ₂ O ₃ in the first insulating film, leakage current (A / cm ² ), and surface roughness Ra for these experimental examples. It is a graph which shows the relationship with (nm) (vertical axis). As can be seen from FIG. 6, when the abundance (mass% ratio) of the spinel mineral to Al ₂ O ₃ is 3% or more and 11% or less, the leakage current and the surface roughness can be reduced.
In addition, No. 2, 10, and 11 are reference examples.

  Experiment No. In Nos. 23 to 35 and 38 to 40, the steel material used and the production conditions are appropriate, the first insulating film having an olivine mineral is formed with an appropriate thickness, and the second insulating film is further formed with an appropriate thickness. Formed. Therefore, the metal substrate excellent in the insulation which can be used suitably for manufacture of an electronic device was able to be obtained.

In particular, Experiment No. 23 to 32, the thickness of the first insulating film is constant at 0.7 μm, the thickness of the second insulating film is constant at 1.5 μm, and the number of moles of Mg, Fe, and Ca with respect to the number of moles of Si. The ratio of the sum of the values is dispersed in the range of 1.1 to 2.1. FIG. 7 shows the ratio of the sum of the number of moles of Mg, Fe and Ca to the number of moles of Si in the first insulating film (horizontal axis) and the leakage current (A / cm ² ) for these experimental examples. It is a graph which shows the relationship with surface roughness Ra (nm) (vertical axis).
As can be seen from FIG. 7, when the ratio of the sum of the number of moles of Mg, Fe, and Ca to the number of moles of Si in the first insulating film is 1.2 to 2.0, the leakage current In addition, the surface roughness can be reduced.
In addition, No. Reference numerals 23 to 35 are reference examples.

Experiment No. 1 and 16 are comparative examples in which the thickness of the first insulating film is small. Since the convex portion of the steel material could not be completely covered with the first insulating film, the coating of the convex portion of the steel material was insufficient even when the second insulating film was formed, and the insulation was not obtained.
Experiment No. 21 is a comparative example in which an oxide scale film was generated due to the small amount of Si + Al in the steel material.
Experiment No. 12 and 20 are comparative examples in which the thickness of the first insulating film is large. In these comparative examples, warping due to the difference in thermal expansion coefficient between the thermal oxide and the steel material occurred in the steel material due to the cooling step in the heat treatment process when forming the first insulating film. If warpage occurs in the substrate, the characteristics of the electronic device formed on the substrate may vary greatly, or the device may not function as a comparative example.
Experiment No. 14 is a comparative example in which the second film is too thick. Although a good leakage current was obtained after the formation of the second insulating film, a heat treatment at 500 ° C. was performed assuming an electronic device manufacturing process. As a result, defects were caused by the volatilization of the components of the second insulating film. The performance as a metal substrate for producing an electronic device could not be obtained.
Experiment No. 15 is a comparative example in which the thickness of the second insulating film is small, and high insulating properties could not be obtained.

Experiment No. 22 and 37 are comparative examples in which the thickness of the first insulating film is small. Since the convex portion of the steel material could not be completely covered with the first insulating film, the coating of the convex portion of the steel material was insufficient even when the second insulating film was formed, and the insulation was not obtained.
Experiment No. 36 and 41 are comparative examples in which the thickness of the first insulating film is large. In these comparative examples, warping due to the difference in thermal expansion coefficient between the thermal oxide and the steel material occurred in the steel material due to the cooling step in the heat treatment process when forming the first insulating film. If warpage occurs in the substrate, the characteristics of the electronic device formed on the substrate may vary greatly, or the device may not function as a comparative example.

  ADVANTAGE OF THE INVENTION According to this invention, the metal substrate and panel excellent in the insulation which can be used suitably for manufacture of an electronic device can be provided.

1 electronic device fabrication metal substrate 10 steel member 11 first insulating film 11a Al ₂ O ₃ layer 11b coating 103 upper electrode 104 voltmeter 105 having a layer 12 second insulating film 101 steel 102 an insulating containing spinel mineral Ammeter 106 Power supply 141 Substrate 142 Back electrode 143 Light absorption layer 144 Buffer layer 145 Semi-insulating layer 146 Window layer 147 Upper electrode 148 Antireflection film 1010 Stainless steel foil 1011 Thermal oxide film 1012 Silica-based inorganic / organic hybrid film

Claims (7)

Al content is from 0.5 to 13.0 wt%, Si content is from 0 to 5.0 wt%, the total content of the Al and the Si is at 0.5 to 18.0 wt% Yes,
A steel material in which the Si content in the steel material is ½ or less of the Al content ;
A first insulating film covering the surface of the steel material and having a thickness of 0.2 μm to 2.0 μm;
A second insulating film covering the surface of the first insulating film and having a thickness of 0.3 μm to 5.0 μm;
With
The total thickness of the first insulating film and the second insulating film is 2.0 μm to 7.0 μm,
The first insulating film is a thermal oxide film containing at least one of Al ₂ O ₃ and SiO ₂ and containing a spinel mineral ,
In the first insulating film, the abundance of the spinel mineral with respect to the Al ₂ O ₃ is 3% or more and 11% or less by mass% ratio,
It said second insulating film is formed from a silica-based inorganic-organic hybrid materials, electronic device fabrication for metal substrate an organic group of the silica-based inorganic-organic hybrid material is characterized by a methyl group or a phenyl group der Rukoto. _2. The electronic device according to claim 1 , wherein in the first insulating film, the Al ₂ O ₃ covers the surface of the steel material, and the spinel mineral does not directly cover the surface of the steel material. Metal substrate for production. Al content is 0 to 13.0 mass%, Si content is 0.5 to 5.0 mass%, Ca content is 0.0001 to 0.1 mass%, Al and the The total content of Si is 0.5 to 18.0 mass%,
And a steel the Al content in the steel is Ru der below half the Si content;
A first insulating film covering the surface of the steel material and having a thickness of 0.2 μm to 2.0 μm;
A second insulating film covering the surface of the first insulating film and having a thickness of 0.3 μm to 5.0 μm;
With
The total thickness of the first insulating film and the second insulating film is 2.0 μm to 7.0 μm,
The first insulating film is a thermal oxide film containing at least one of Al ₂ O ₃ and SiO ₂ and containing an olivine mineral ,
In the first insulating film, the ratio of the sum of the number of moles of Mg, Fe, and Ca to the number of moles of Si is 1.2 or more and 2.0 or less,
It said second insulating film is formed from a silica-based inorganic-organic hybrid materials, electronic device fabrication for metal substrate an organic group of the silica-based inorganic-organic hybrid material is characterized by a methyl group or a phenyl group der Rukoto. Wherein in the first insulating film, the SiO ₂ is covering the surface of the steel material, the olivine mineral electronic device manufactured according to claim 3, characterized in that it does not cover the surface of the steel material directly Metal substrate. The metal substrate for producing an electronic device according to any one of claims 1 to 4, wherein a surface roughness Ra measured in a 1 µm square region of the second insulating film is less than 2 nm. The metal substrate for producing an electronic device according to any one of claims 1 to 5, wherein the steel material is a stainless steel foil containing 19 mass% or more of Cr and having a thickness of 150 µm or less. Panel, characterized in that the electronic device is formed on the electronic device fabrication metal substrate according to any one of claims 1-6.