JP2000349320A - Insulating material made of aluminum alloy excellent in withstand voltage characteristic and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide insulating material excellent in withstand voltage characteristic which is more lightweight and thermally conductive than a glass substrate, hard to break, flexible and suitable for a solar battery substrate and a printed wiring board. SOLUTION: In insulating material made of Al alloy in which an anodic oxidaized film having pores is formed on an Al base material surface, the thickness of the anodic oxidized film is made at least 0.5 μm, and a plurality of holes which are stretched in the direction almost rectangular to the axis center of the pores are formed on the anodic film. The insulating material made of Al alloy in which the pores and/or the holes are filled with compound having Si-O bonds exhibits more excellent withstand voltage characteristic and is desirable. When the material is manufactured, solution containing compound having Si-O bonds is spread on insulating material having holes, and baking may be performed at 100 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an A film having excellent withstand voltage characteristics suitable for a thin film solar cell substrate or a printed wiring board.
1. Field of the Invention The present invention relates to a 1-alloy insulating material and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a substrate for a thin-film solar cell, a glass substrate is mainly used. However, the glass substrate is fragile and requires careful attention in handling, and its application range is limited due to lack of flexibility. Recently, solar cells are attracting attention as a power supply source for buildings such as houses, and in order to secure sufficient power supply, it is essential to increase the size of the solar cells. Therefore, it is desired to reduce the weight of the substrate. However, for the purpose of weight reduction, when the glass substrate is made thinner, the glass substrate is more likely to be broken. Therefore, there is a demand for a substrate material which is hard to be broken and is flexible and which can achieve a lighter weight than the glass substrate.

Although a metal material is hard to be broken even when it is thin, it has hardly been studied as an insulating substrate material replacing glass because it is a conductor. It should be noted that a material obtained by subjecting an Al alloy surface to anodic oxidation treatment is used for general building materials and the like, and it is known that the anodic oxide film itself has excellent corrosion resistance and insulation properties. However, since the temperature is high in the film forming process of the thin-film solar cell, a crack is generated in a normal anodic oxide film, and the insulating property is impaired during the manufacturing. That is, the anodic oxide film often undergoes cracking when subjected to a thermal history, and particularly when the film is thickened to increase the insulation properties, cracking is likely to occur, and the corrosion resistance and insulation properties are rather impaired. Therefore, it could not be applied.

Japanese Patent Application Laid-Open No. Hei 5-191001 discloses that
Anodized metal plates for printed wiring etc. have been proposed for the purpose of increasing the heat conductivity of resin substrates in response to the higher integration of electronic devices. Layer, and the anodic oxide layer itself is 5000
Insulation is small as below. Even if a metal wiring is directly formed on the anodic oxide layer in the same manner as in the process of manufacturing a solar cell using a glass substrate, the insulating property required at the time of manufacturing the solar cell cannot be obtained because the anodic oxide layer is thin.

Further, a thin anodic oxide film of about 0.4 μm called a barrier type is used as a dielectric of the electrolytic capacitor, and a withstand voltage of 100 V or more is obtained. However, the substrate is limited to special high-purity aluminum, and the surface is greatly affected by minute scratches, etc., and application to large-area substrates such as solar cells is extremely limited in terms of strength and manufacturing method, and is extremely limited. Have difficulty. Furthermore, the withstand voltage obtained by this method is about 7
The upper limit is 00 V, which is not applicable when higher withstand voltage is required.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is lighter and lighter than a glass substrate.
An object of the present invention is to provide an insulating material having high thermal conductivity, resistance to cracking, and flexibility, and excellent in withstand voltage characteristics suitable for a solar cell substrate, a printed wiring board, and the like.

[0007]

The Al alloy insulating material according to the present invention which has solved the above-mentioned problems is an Al alloy insulating material in which an anodic oxide film having pores is formed on the surface of an Al base material. The gist is that the thickness of the anodic oxide film is 0.5 μm or more and that the anodic oxide film has a plurality of holes extending in a direction substantially perpendicular to the axis of the pore. .

The cross section in the growth direction of the anodic oxide film is observed with a transmission electron microscope, and when a plurality of squares each having a line connecting adjacent pores as one side are selected, the vacancies are formed in a square region of 20% or more thereof. Is desirably present, and the area ratio occupied by the holes is preferably 1 to 50%.

Further, S is formed inside the pores and / or holes.
An Al alloy insulating material filled with a compound having an i-O bond is preferable because it exhibits more excellent withstand voltage characteristics. In producing the Al alloy insulating material,
A solution containing a compound having a Si—O bond may be applied to the insulating material having pores and then fired at 100 ° C. or higher.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors formed an insulating layer (anodic oxide film) on a metal substrate by anodizing treatment, and closed an electronic material substrate in which the pores of the anodized film were closed with a non-conductive substance. Developed and filed earlier (Japanese Patent Application No. 10-13)
7139). Then, as a result of further research, they found an insulating layer structure capable of realizing higher withstand voltage in a large area, and reached the present invention. FIG. 1 shows a schematic diagram of the cross-sectional structure, and FIG. 2 shows an example observed by a transmission electron microscope (TEM).

In the case of a solar cell substrate, the temperature may be 200 ° C. or higher in the process of forming the photoelectric element. However, when ordinary anodic oxidation, which is generally called hard alumite, is applied, cracks easily occur during heating, and However, even if the insulating property could be ensured, when the area became large, conduction from the cracks was unavoidable and stable insulating property could not be obtained. FIG. 3 shows the cross-sectional structure of anodic oxidation, which is liable to crack during heating.
On the other hand, as shown in FIG. 1, a structure having pores extending in a direction substantially perpendicular to the pores extending in the growth direction in the anodic oxide layer suppresses cracking during heating that causes conduction. You. As a result, even if it is used as a large-area plate material, sufficient insulation can be ensured over the entire surface.

The more the pores are dispersed in the anodic oxide film, the greater the effect of suppressing cracking and the more excellent the flexibility. The cross section in the growth direction of the anodic oxide film was observed by a transmission electron microscope, and when a plurality of squares (see FIG. 1) each having a line connecting adjacent pores as one side were selected, the square region of 20% or more was selected. The presence of vacancies is desirable for obtaining excellent insulation properties.
For application in combination with i-oxide coating, a structure having a void-containing area ratio of 70% or more is more preferable.

Further, in order to obtain the effect of suppressing cracks, the area ratio of the pores is 1% in the field of view of the cross section observed by a transmission electron microscope.
It is preferably at least 5%, more preferably at least 5%. On the other hand, if the void portion is too large, the void itself becomes a conductive portion and the insulating property is rather deteriorated. Therefore, the upper limit of the void area ratio is desirably 50%, and more desirably 20% or less.

In order to ensure stable insulation, the thickness of the insulating layer is preferably 0.5 μm or more. The required withstand voltage varies depending on the use conditions of individual components, and a thick insulating layer is applied to components requiring high withstand voltage. For example, when a withstand voltage of 2 kV is required, the insulating layer thickness is 50 to 50 kV. 70 μm
Is appropriate. The upper limit of the thickness of the insulating layer is not particularly limited in terms of withstand voltage and corrosion resistance, but in general, an insulating inorganic compound such as an anodized layer is easily broken when it is thick, and cannot exhibit the flexibility characteristic of a metal substrate. So
The thickness of the insulating layer is preferably 100 μm or less.

The base alloys are 1000 series, 3000 series, 50 series.
Al alloys such as 00 series and 6000 series can be applied, and as the anodizing bath, an oxalic acid bath or a sulfuric acid bath can be applied. However, the internal structure of the anodized film differs depending on the alloy and the processing conditions. Is obtained. For example, for a solar cell substrate requiring a withstand voltage of 2 kV, M
Using a 3000 series alloy containing n or an Al alloy such as a 6000 series alloy containing Mg and Si, anodizing at 30 to 90 V is performed with a treatment solution containing 2 to 4% oxalic acid. Therefore, it is recommended to adopt an insulating layer having a thickness of 45 to 70 μm. still,
When the required withstand voltage is about 1 kV, a material having an insulating layer thickness of 10 to 30 μm by the same processing method may be used. Furthermore, A other than 3000 series and 6000 series
An anodic oxide film having an internal structure as shown in FIG. 1 can be obtained depending on the combination with electrolytic conditions such as AC superposition and current reversal, even if a treatment solution other than 1 alloy or oxalic acid is used.

Further, a higher withstand voltage can be realized by forming a structure in which pores and / or vacancies are filled with an Si oxide after anodizing. Filling with a Si oxide is possible by a method of baking after applying a solution containing a compound having a Si-O bond. In the conventional anodic oxide film structure shown in FIG. 3, cracks are likely to occur during firing, and the insulating property may be lowered by firing, but in the anodic oxide structure according to the present invention shown in FIG. 1, the insulating property is improved.

The compound having a Si--O bond may be in any state of a monomer, an oligomer or a polymer, and may be an organopolysiloxane or an organosilsesquioxane having a functional group such as a methyl group or a phenyl group in a side chain. (Eg, phenylsilsesquioxane), silanol, or the like may be used. These compounds are dissolved in a solvent,
After applying or impregnating the anodic oxide film, it may be fired to form Si oxide. For filling the Si oxide, a technique called SOG (Spin on G1ass) or coated glass in the field of electronics industry can be used. As a solvent for dissolving the compound having the Si—O bond, an organic solvent such as toluene, ethanol, isopropanol, butanol, methyl isobutyl ketone (MIBK), acetone, ethyl acetate, or butyl acetate may be used. The firing temperature condition may be appropriately selected according to the type of the compound having a Si-O bond, and for example, in the case of a polyorganosiloxane having a methyl group and a phenyl group in a side chain at a molar ratio of 2: 1, 150 to 350 The sintering may be carried out at a temperature of 150 ° C., or in the case of a polyorganosiloxane having only a methyl group in the side chain, the sintering may be carried out at a temperature of 150 ° C. or less.

The substance to be filled in the pores and / or the pores may be a non-conductive substance other than a compound having a Si—O bond.
Zr, Ti, Li, Mg, Sn, Zn, Y, B, Ba,
Oxides, hydroxides, oxyhydroxides, and nitrides containing one or more of Ta, Nb, K, and Pb may be used as the sealing material.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples do not limit the present invention, and any design changes based on the above and following gist will be described. Are included within the technical scope of

[0020]

EXAMPLES An Al alloy shown in Table 1 was used as a substrate, and anodic oxide films (insulating layers) of various thicknesses were formed under the anodic oxidation treatment conditions shown in Table 1. These anodized films are
Using a transmission electron microscope, observe the cross section in the growth direction of the anodic oxide film, arbitrarily select 100 squares with the distance between adjacent pores as one side, and vacancies extending in the square in a direction substantially orthogonal to the pores Were counted and the ratio was determined. In each region, the area ratio occupied by vacancies in portions other than the pores was determined, and the average value was calculated.

After the anodizing treatment of the test substrate, polymethylsilsesquioxane is dissolved in methyl isobutyl ketone.
After applying the dispersed solution and evaporating the solvent at 80 ° C,
Firing was performed by heating at 140 ° C. for 5 minutes in the air and then at 300 ° C. for 30 minutes in an N ₂ atmosphere to fill the pores and holes in the anodic oxide layer (No. 5 This is an example of the present invention in which only an anodizing treatment is not performed and Si oxide is filled). 5cm × 4 on these substrates
cm Al electrode was formed, the voltage was increased to 0 to 3 kV, and the withstand voltage was evaluated based on the voltage at which the leakage current exceeded 10 ⁻⁶ A / mm ² .

The results are shown in Table 1.

[0023]

[Table 1]

No. 1 to 6 are substrates according to the present invention, and excellent withstand voltage characteristics were obtained.

On the other hand, the anodic oxide film having no internal structure as in the present invention No. 7 to 9, the withstand voltage was very low. No. In No. 7, although the average film thickness was small, the film itself was hard to crack, but no insulating property was obtained. This is presumed to be due to the fact that there was almost no portion of the insulating layer due to fluctuations in the film thickness caused by minute irregularities of the substrate in the measurement range, or the insulating layer was broken by contact with the probe during measurement. No. In Nos. 8 to 9, it is considered that no holes were introduced into the anodic oxide layer (the structure of FIG. 3), so that the insulating layer was cracked during the firing of the Si oxide, and conduction was caused at the cracked portion.

[0026]

As described above, according to the present invention, it is possible to provide an insulating material which is lighter in weight, has higher thermal conductivity, is flexible and has excellent withstand voltage characteristics, as compared with a glass substrate.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a structure of an anodic oxide film according to the present invention.

FIG. 2 is a TEM observation example (T
(Copy of EM photograph).

FIG. 3 is a schematic view showing the structure of a conventional anodic oxide film.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takuya Masui 1-5-5 Takatsukadai, Nishi-ku, Kobe, Japan Inside Kobe Research Institute, Kobe Steel Ltd. (72) Inventor Kohei Suzuki 1-chome, Takatsukadai, Nishi-ku, Kobe-shi No. 5-5 Kobe Steel, Ltd. Kobe Research Institute (72) Inventor Fumio Uekubo 1-5-5, Takatsukadai, Nishi-ku, Kobe City F-term, Kobe Steel Research Institute Kobe Research Institute (Reference) 5E315 AA03 AA05 BB03 BB11 CC19 DD08 GG03 GG18 5F051 BA15 GA02 GA03 GA05 GA06 GA20

Claims (7)

[Claims] 1. An insulating material made of an Al alloy in which an anodic oxide film having pores is formed on the surface of an Al substrate, wherein the thickness of the anodic oxide film is 0.5 μm or more. Characterized by having a plurality of holes extending in a direction substantially perpendicular to the axis of the pore. 2. A cross section of the anodic oxide film in a growth direction is observed by a transmission electron microscope, and when a plurality of squares each having a line connecting adjacent pores as one side are selected, the square region of 20% or more is selected. 2. The Al according to claim 1, wherein vacancies are present.
Alloy insulating material. 3. A cross section in the growth direction of the anodic oxide film is observed with a transmission electron microscope, and when a plurality of squares each including a line connecting adjacent pores as one side are selected, the area ratio of the holes is 1%. The insulating material made of an Al alloy according to claim 1 or 2, which is 50% or less. 4. The method according to claim 1, wherein said pores and / or voids have Si-
The insulating material made of an Al alloy according to any one of claims 1 to 3, which is filled with a compound having an O bond. 5. A method according to claim 4, wherein a solution containing a compound having a Si—O bond is applied to the insulating material according to claim 1 and then fired at 100 ° C. or higher. A method for producing an Al alloy insulating material. 6. A thin-film solar cell substrate comprising the insulating material according to claim 1. Description: 7. A printed wiring board comprising the insulating material according to claim 1.