JP6915307B2 - Substrate base material for flexible devices and its manufacturing method - Google Patents

Description

The present invention relates to a base material for a substrate for a flexible device and a method for manufacturing the same. More specifically, the present invention is flexible in that it has excellent adhesion to a glass layer and can reduce surface defects of the formed glass layer. The present invention relates to a base material for a substrate for a device and a method for manufacturing the same.

Substrates for flexible devices used for organic EL lighting, organic EL displays, organic solar cells, etc. are required to have smoothness and insulation properties in addition to barrier properties such as moisture barrier property and vapor barrier property.
Patent Document 1 below proposes a structure of an organic EL element in which a transparent conductive layer, an organic light emitting medium layer, and a cathode layer are sequentially laminated on a plastic film base material, and a metal foil is laminated via an adhesive layer. However, such a plastic film base material is not satisfactory in terms of moisture barrier property.
Further, Patent Document 2 below proposes a substrate for a flexible device in which a flattening layer made of a polyimide resin is provided on a stainless steel base material, but since the polyimide resin has high water absorption, it also has a moisture barrier property. I am not satisfied with it.
Further, Patent Document 3 below proposes a flexible solar cell substrate in which silica-based glass is formed on a stainless steel base material. Silica-based glass generally has a smaller coefficient of thermal expansion than stainless steel, and is compatible with stainless steel base materials. In addition to lacking adhesion, silica-based glass has the problem of being vulnerable to bending and impact.
Various glass substrates that can be used as substrates for thin-film electric circuits and flexible displays have also been proposed (Patent Document 4, etc.), but glass substrates are characterized by being vulnerable to bending such as twisting, and are stronger as substrates for flexible devices. Higher ones are desired.

In order to solve such a problem, the present inventors have formed a nickel plating layer on the surface of a metal base material, and laminated bismuth-based glass having electrical insulation on the surface of the nickel plating layer. A metal substrate for a flexible device has been proposed (Patent Document 5).

Japanese Unexamined Patent Publication No. 2004-171806 Japanese Unexamined Patent Publication No. 2011-97007 Japanese Unexamined Patent Publication No. 2006-80370 Japanese Unexamined Patent Publication No. 2012-197185 Japanese Unexamined Patent Publication No. 2014-107053

The metal substrate for a flexible device has excellent bending resistance because bismuth-based glass having excellent moisture barrier properties and adhesion to the metal substrate is laminated on a metal substrate having excellent mechanical strength. In addition, it has excellent insulation and flatness, and is lightweight and flexible. However, the surface of the glass layer after firing may be repelled by minute recesses, and such minute defects cause glass. The smoothness of the layer was sometimes impaired.
As a result of researching the cause of the repellent formed on the surface of the glass layer, the present inventors have found that the repellent formed on the surface of the glass layer has rupture marks due to air bubbles, decomposition products of the resin, or outgas when the glass is melted. It was found that the cause was the cause or the influence of surface tension.

Therefore, an object of the present invention is to obtain a substrate for a substrate for a flexible device and a method for manufacturing the same, which are excellent in adhesion of the glass layer and can effectively suppress the occurrence of surface defects such as cissing on the surface of the formed glass layer. To provide.

According to the present invention, a nickel-plated metal base material having a nickel-plated layer formed on at least one surface of the metal base material or a base material for a flexible device substrate made of a nickel-based base material, wherein the nickel-plated layer is formed. the surface or nickel-based base material surface, and the oxide film is formed having an uneven thickness of the oxide film, the range near the 40~1200nm is, the arithmetic average roughness of the oxide film (Ra ) Is in the range of 30 to 100 nm, and the maximum height roughness (Rz) of the surface of the oxide film is in the range of 420 to 900 nm. NS.
In the substrate substrate for flexible devices of the present invention,
1 . Thickness before Symbol oxide film, in the range of 500 to 1000 nm,
2 . Iron is present on the surface layer of the nickel plating layer or the surface layer of the nickel-based base material.
3 . Of the iron present on the surface layer of the nickel plating layer or the surface layer of the nickel-based base material, metallic iron is 3 atomic% or less.
4 . The ratio of oxygen in the surface layer of the nickel plating layer or the surface layer of the nickel-based base material is 30 atomic% or more.
5 . The proportion of metallic nickel in the surface layer of the nickel plating layer or the surface layer of the nickel-based base material is 20 atomic% or less.
Is preferable.

According to the present invention, a nickel-plated metal base material or a nickel-based base material having a nickel plating layer formed on at least one surface of the metal base material is fired in an oxygen-containing atmosphere to obtain the surface of the nickel plating layer or the surface of the nickel plating layer. a nickel-based substrate surface, thickness of Ri range near the 40～1200Nm, arithmetic average roughness (Ra) is in the range of 30 to 100 nm, the maximum height surface roughness (Rz) is, 420～900Nm Provided is a method for producing a base material for a substrate for a flexible device, which comprises forming an oxide film in the range of.

In the base material for a substrate for a flexible device of the present invention, an oxide film having irregularities on the surface is formed on the surface of the nickel plating layer or the surface of the nickel-based base material of the nickel-plated metal base material, so that the nickel plating layer is formed. Adhesion to the glass layer formed as an insulating layer on the surface or the surface of the nickel-based base material is remarkably improved, and when used for a substrate for a flexible device, peeling of the glass layer even when subjected to a roll-to-roll process, etc. It is possible to develop sufficient flexibility that does not occur.
Further, since the unevenness is formed on the surface of the oxide film, it is possible to suppress the spreading of the glass at the time of forming the glass layer, so that the occurrence of cissing on the surface of the glass layer can be effectively suppressed.
Further, according to the method for producing a base material for a substrate for a flexible device of the present invention, a nickel-plated metal base material or a nickel-based base material is calcined in an oxygen-containing atmosphere to obtain a nickel-plated layer surface or a nickel-based base material surface. It is possible to form an oxide film having the above-mentioned functions, and as a result, an oxide film having irregularities on the surface capable of forming a glass layer without surface defects can be easily and continuously produced. It is also excellent in productivity and economy.

It is a figure for demonstrating the cross-sectional structure of an example of the substrate base material for a flexible device of this invention. The base material No. of the nickel-plated steel sheet in Table 1. SEM photographs ((A) to (D)) of the surface of the nickel plating layer after calcining for 1, 2, 6 and 10 and the base material No. 4 is an SEM photograph (E) of the surface of the nickel plating layer of No. 4.

The base material for a substrate for a flexible device of the present invention is a nickel-plated metal base material or a nickel-based base material having a nickel-plated layer formed on at least one surface of the metal base material.
An important feature is that an oxide film having irregularities on the surface is formed on the surface of the nickel plating layer or the surface of the nickel-based base material.
FIG. 1 is a diagram showing a cross-sectional structure of the base material for a substrate for a flexible device of the present invention, which uses a nickel-plated metal base material having a nickel-plated metal base material 11 formed on the surface of the metal base material 10. An oxide film 12 is formed on the surface of the oxide film 11, and the surface of the oxide film 12 is formed on the uneven surface 12a.

[Metal base material]
The metal base material for forming the nickel plating layer used for the base material for the substrate for the flexible device of the present invention is not limited to this, but iron, stainless steel, titanium, aluminum, copper and the like can be used, and heat can be used. It is preferable to use one having an expansion coefficient in the range of 8 × 10 ^{-6 to} 25 × 10 ^-6 / ° C., particularly 10 × 10 ^{-6 to} 20 × 10 ^{-6 / ° C.}
Further, in the present invention, the metal base material itself may be a nickel-based base material, that is, a pure nickel plate or a nickel alloy plate without forming a nickel plating layer. In the nickel alloy plate, iron (Fe), copper (Cu), and chromium (Cr) can be used as the metal that can be alloyed with nickel.
The thickness of the metal base material or the nickel-based base material is preferably in the range of 10 to 200 μm, particularly 20 to 100 μm, whereby sufficient flexibility can be obtained.

[Nickel plating layer]
In the base material for a substrate for a flexible device of the present invention, the nickel plating layer formed on the surface of the metal base material is a layer formed by nickel plating, and is either electrolytic plating or electroless plating as described later. May be good. In the example shown in FIG. 1, the nickel plating layer was formed only on one surface of the metal base material, but of course, it may be formed on both sides of the metal base material.
The thickness of the nickel plating layer preferably is in the range of 0.1 to 10 μm, particularly 0.5 to 5 μm, including the oxide film, and the thickness of the nickel plating layer is thinner than the above range. The adhesion of the glass layer becomes inferior as compared with the case where it is in the above range, and on the other hand, even if the thickness of the nickel plating layer is thicker than the above range, no further effect can be expected and it is inferior in economic efficiency. Become.
The nickel plating layer may have an alloy layer at the interface with the metal base material.

[Oxide film]
As described above, in the present invention, it is an important feature that an oxide film having an uneven surface is formed on the surface of the nickel plating layer or the nickel-based base material, and this oxide reacts with glass. As a result, an adhesive layer is formed, and the adhesiveness of the glass layer is improved. Therefore, the amount of metallic nickel present on the surface of the nickel plating layer or the nickel-based base material is preferably 20 atomic% or less, particularly preferably 18 atomic% or less.
The oxide film is composed of at least nickel oxide formed by calcining the surface of the nickel plating layer or the nickel-based base material in an oxygen-containing atmosphere described later, but diffused from the nickel oxide and the metal base material. It may consist of metal oxides.
That is, when a steel plate is used as the metal material or a nickel-iron alloy plate is used as the nickel-based base material, it is desirable that iron is present on the surface of the nickel plating layer or the nickel-based base material, and this surface. Since the iron present in is present as an oxide, the adhesion of the glass layer can be further improved in combination with the nickel oxide. Therefore, among the irons present in the surface layer of the nickel plating layer or the surface layer of the nickel-based base material, the metal Iron is preferably 3 atomic% or less.

Further, it is preferable that the ratio of oxygen in the surface layer of the nickel plating layer or the surface layer of the nickel-based base material is in the range of 30 atomic% or more, particularly 35 to 50 atomic%, whereby the oxide film having excellent adhesion to the glass layer is formed. Is formed.

In the present invention, irregularities (rough surfaces) are formed on the surface of the oxide film by forming convex portions that are considered to be crystal grains, whereby the spread of the glass composition is suppressed during the formation of the glass layer. Therefore, the occurrence of repelling is effectively suppressed.
The irregularities (surface roughness) on the surface of the oxide film have an arithmetic average roughness (Ra) in the range of 30 to 100 nm, particularly 50 to 90 nm, and a maximum height roughness (Rz) of 420 to 900 nm, particularly 600 to. It is desirable that it is formed so as to be in the range of 850 nm.
The thickness of the oxide film is preferably in the range of 40 to 1200 nm, preferably 500 to 1000 nm, and more preferably 500 to 900 nm. If the thickness of the oxide film is thinner than the above range, the surface modification of the nickel plating layer or the nickel-based base material may be insufficient as compared with the case where the thickness is within the above range, while the surface modification is less than the above range. When the thickness of the oxide film is thick, the alloying of the nickel plating layer surface layer or the nickel-based base material surface layer progresses and the nickel plating layer surface layer or the nickel-based base material surface layer becomes weaker than in the above range. There is a risk that the surface layer of the nickel plating layer or the surface layer of the nickel-based base material may peel off.

(Manufacturing method of substrate for flexible device substrate)
The base material for a substrate for a flexible device of the present invention is obtained by firing a nickel-plated metal base material or a nickel-based base material having a nickel plating layer formed on at least one surface of the metal base material in an oxygen-containing atmosphere. It can be produced by a production method including an oxide film forming step of forming an oxide film on the surface of a nickel plating layer or the surface of a nickel-based base material.

[Nickel plating layer forming process]
In the metal substrate for a flexible device of the present invention, the method itself for forming the nickel-plated layer on the nickel-plated metal substrate can be performed by a conventionally known method.
In the nickel plating layer forming step, the treatment method differs depending on the metal base material used, but when a steel plate is used as the metal base material, it is degreased by alkaline electrolysis or the like prior to the plating treatment, washed with water, and then sulfuric acid. A conventionally known pretreatment such as pickling by dipping or the like is performed.
As described above, the nickel plating layer can be formed on the pretreated metal base material by a conventionally known plating method such as electrolytic plating or electroless plating. From the viewpoint of continuous productivity, electrolytic plating is preferable. As the nickel plating bath, a commonly used bath such as a watt bath or a sulfamic acid bath can be used according to a known formulation under known electrolytic conditions. As described above, the nickel plating layer is preferably formed so as to have a thickness in the range of 0.1 to 10 μm, particularly 0.5 to 5 μm.

[Oxide film forming process]
In the method for producing a base material for a substrate for a flexible device of the present invention, the surface of the nickel plating layer or the surface of a nickel-based base material is calcined in an oxygen-containing atmosphere to obtain the surface of the nickel plating layer or nickel. It is important to form an oxide film with irregularities on the surface of the base material.
The calcining conditions are not particularly limited as long as the above-mentioned oxide film is formed, but the calcining temperature is preferably 550 to 900 ° C., particularly preferably 750 to 850 ° C. The calcining time can be appropriately changed depending on the oxygen concentration of the oxygen-containing atmosphere and the calcining temperature. However, when calcining in the air in the above temperature range, the calcining time is calcined at the above calcining temperature for 5 to 120 seconds. It is preferable to do so. As described above, the oxide film is preferably formed in the range of 40 to 1200 nm, preferably 500 to 1000 nm, and more preferably 500 to 900 nm.
Depending on the calcining conditions, an alloy layer may be formed on the surface of the nickel plating layer or the nickel-based base material by the firing for forming the oxide film in this step.

(others)
As described above, the substrate for a flexible device substrate of the present invention can be suitably used as a substrate for a substrate for a flexible device having a glass layer as an insulating layer.
The glass layer that can be formed on the oxide film having irregularities on the surface of the substrate for the flexible device of the present invention is not limited to those that have been conventionally used as an insulating layer for organic EL lighting or the like or a transparent substrate. Low melting point glass such as tin-phosphate-based glass, bismuth-based glass, vanadium-based glass, and lead-based glass can be used, and is not limited thereto. Among these, bismuth-based glass having excellent moisture barrier properties and excellent adhesion to a metal substrate can be suitably laminated.
As the bismuth-based glass, bismuth-based glass having an electrically insulating property with a softening point temperature of 300 to 500 ° C. is preferable, and in particular, a glass _{containing Bi 2} O ₃ as a main component (particularly 70% by weight or more) as a glass composition is preferable. preferable.

When the substrate for a flexible device is formed using the substrate for a substrate for a flexible device of the present invention, the glass layer is formed by firing using a glass frit having an average particle size of 20 μm or less, preferably 1 to 10 μm. NS. When bismuth-based glass is used, the firing temperature and firing time for forming the glass of the glass layer are 430 ° C. or higher and lower than 900 ° C. for 10 seconds to 30 minutes.
The glass layer formed on the substrate substrate for a flexible device of the present invention has a smooth surface roughness (Ra) of 10 nm or less, and does not have surface defects such as repelling.

(Base materials Nos. 1 to 11 and 15)
1. 1. Nickel-plated steel sheet [metal base material]
As a metal base material, a steel sheet obtained by annealing and degreasing a cold rolled plate (thickness 50 μm) of ordinary steel having the chemical composition shown below was prepared.
Composition: C; 0.03% by weight, Si; 0.01% by weight, Mn; 0.25% by weight, P; 0.008% by weight, S; 0.005% by weight, Al; 0.051% by weight, Remaining; Contains Fe and inevitably contained components.
[Formation of nickel plating layer]
Next, the prepared steel sheet (size: length 12 cm, width 10 cm, thickness 50 μm) was subjected to alkaline electrolytic degreasing and pickling by immersion in sulfuric acid, and then nickel-plated under the following conditions to have a thickness of 1 μm and a surface roughness (thickness: 1 μm). Ra) A nickel plating layer of 30.1 nm was formed on both sides.
Bath composition: Nickel sulfate 300 g / L, nickel chloride 40 g / L, boric acid 35 g / L, pit inhibitor (sodium lauryl sulfate) 0.4 mL / L
pH: 4 to 4.6
Bath temperature: 55 ° C-60 ° C
Current density: 25A / dm ²

2. Pure nickel plate As a nickel-based base material, a pure nickel plate having a thickness of 100 μm was prepared.

3. 3. Formation of Oxide Film Using the above nickel-plated steel plate and pure nickel plate, under the conditions shown in Table 1, the base material No. Nickel-plated steel sheets 1 to 3, 5 to 7, 15 and base material No. Pure nickel plates 13 and 14 were calcined using a thin steel plate heat treatment simulator (manufactured by Vacuum Riko Co., Ltd., product number; CCT-AV). Base material No. For comparison, 4 and 12 were not calcined. In addition, the base material No. 8 to 11 were temporarily baked in an NH atmosphere.
Temporarily baked nickel-plated steel sheet, base material No. No. 4 nickel-plated steel plate, calcined pure nickel plate, and base material No. Arithmetic mean roughness (Ra), maximum height roughness (Rz), and surface oxide thickness of 12 pure nickel plates were examined as surface roughness. The results are also shown in Table 1.
In addition, the base material No. SEM photographs of the surface of the nickel plating layer after calcining for 1, 2, 6 and 10, and the base material No. The SEM photograph of the surface of the nickel plating layer of No. 4 is shown in FIG.
The thickness and surface roughness (Ra, Rz) of the oxide film in Table 1 were measured by the following methods.
Arithmetic Mean Roughness (Ra) and Maximum Height Roughness (Rz): Measured in the SPM measurement mode of a microscope (Olympus, Nanosearch microscope, product number; OLS3500) in accordance with JIS B 0601.
Oxide film thickness: Measured using a field emission Auger microprobe (AES: JEOL Ltd., product number JAMP-9500F).

4. Measurement of the surface layer of the base material by XPS For the surface layers of 1, 4, 6, 10 and 11, the ratio of carbon, oxygen, iron and nickel (total 100 atomic%), the ratio of metallic iron and iron oxide (total 100 atomic%), and metallic nickel and nickel oxide (100 atomic% in total) was measured using a scanning XPS microprobe (XPS device ULVAC-PHI product number PHI5000 VersaProbeII). The results are shown in Table 2.

5. Confirmation of the presence of iron on the surface layer of the base material The presence of iron was confirmed on the surface layers of Samples 1, 4, 6, 12 to 14 using the XPS device. The results are shown in Table 3.

6. Formation of glass layer Solventing step: The surfaces of the substrates 1 to 15 were wiped off with gauze soaked in alcohol and degreased.
Coating film forming step: Prepare a binder solution in which water and a binder are mixed, mix the binder solution and a bismuth-based glass frit having the following composition in a mortar so that the weight ratio is 50:50, and put them into a ceramic roll. The dispersion treatment was carried out to prepare a glass paste for forming a coating film. Then, a glass paste for forming a coating film was applied to the surface of each base material with a bar coater so that the film thickness after firing was 20 μm to form a coating film.
Glass composition: As the glass frit, a bismuth-based glass frit containing 70 wt% or more of _{Bi 2} O _{3 as a main component was used.}
Baking step: Drying (temperature: 160 ° C., time: 2 minutes) and firing (temperature: 750 ° C., time: 10 seconds) were carried out using a programmable electric furnace.

7. Evaluation of glass layer The presence or absence of air bubbles and the presence or absence of repellency in the glass film of the flexible device substrate on which the glass layer was formed were evaluated as follows. The results are shown in Table 4.
The main cause of cissing is air bubbles, but since there are also cissing other than those caused by air bubbles, the presence or absence of air bubbles and the presence or absence of all cissing (including those caused by air bubbles) were evaluated separately.
[Bubble evaluation]
In the bubble evaluation, for a flexible device substrate having a size of 100 x 100 mm, bubbles are generated when the focus is moved from the surface of each base material (the interface between each base material and the glass layer) toward the surface of the glass layer with an optical microscope. Judgment was made based on whether or not it could be confirmed.
[Flick evaluation]
In the repelling evaluation, the number of repellents that can be visually confirmed was evaluated according to the following evaluation criteria for the same 100 × 100 mm size flexible device substrate.
◎: No repellent ○: Number of repellents less than 5 △: Number of repellents 5 or more and less than 10 ×: Number of repellents 10 or more [Comprehensive evaluation]
From the above bubble evaluation and cissing evaluation, a comprehensive evaluation was performed according to the following criteria.
◎: No bubbles or repelling ○: There are bubbles, but the number of repelling is less than 10. ×: There are bubbles and the number of repelling is 10 or more.

In the base material for a substrate for a flexible device of the present invention, the adhesion of the glass layer is excellent, and the occurrence of surface defects such as repelling on the surface of the formed glass layer can be effectively suppressed. Therefore, the glass layer is particularly effective. Can be suitably used as a substrate for a flexible device used in an organic EL illumination, an organic EL display, an organic thin film solar cell, or the like, which has an insulating layer.
Further, the base material for a substrate for a flexible device of the present invention can be particularly preferably used for applications in which the above glass layer is formed, but the present invention is not limited to this, and an inorganic film by sputtering or vapor deposition, or a resin film such as a polyimide resin can be used. It is also possible to form.

1 Substrate base material for flexible devices, 10 metal base material, 11 nickel plating layer, 12 oxide film.

Claims (7)

A nickel-plated metal base material having a nickel-plated layer formed on at least one surface of the metal base material or a base material for a substrate for a flexible device made of a nickel-based base material.
The nickel plating layer surface or a nickel-based base material surface is formed with an oxide film having an uneven thickness of the oxide film, the range near the 40~1200nm is, the arithmetic mean of the oxide film roughness (Ra) is in the range of 30 to 100 nm, the maximum height surface roughness of the oxide film (Rz) is, for a substrate for a flexible device, wherein the range near Rukoto of 420~900nm Base material. The oxide thickness of the film, according to claim 1 Symbol mounting a flexible device for board base material is in the range of 500 to 1000 nm. The base material for a substrate for a flexible device according to claim 1 or 2 , wherein iron is present on the surface layer of the nickel plating layer or the surface layer of a nickel-based base material. The base material for a substrate for a flexible device according to claim 3 , wherein the metallic iron is 3 atomic% or less among the iron existing on the surface layer of the nickel plating layer or the surface layer of the nickel-based base material. The base material for a substrate for a flexible device according to claim 1 to 4 , wherein the ratio of oxygen in the surface layer of the nickel plating layer or the surface layer of the nickel-based base material is 30 atomic% or more. The base material for a substrate for a flexible device according to any one of claims 1 to 5 , wherein the ratio of metallic nickel to the nickel present on the surface layer of the nickel plating layer or the surface layer of the nickel-based base material is 20 atomic% or less. By firing a nickel-plated metal base material or a nickel-based base material having a nickel-plated layer formed on at least one surface of the metal base material in an oxygen-containing atmosphere, the surface of the nickel-plated metal base material or the nickel-based base material can be formed . thickness Ri range near the 40～1200Nm, arithmetic average roughness (Ra) is in the range of 30 to 100 nm, the maximum height surface roughness (Rz) is an oxide film in the range of 420~900nm A method for producing a base material for a substrate for a flexible device, which comprises forming the above.

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