JP6078319B2 - Manufacturing method of input device, substrate with conductive film used therefor, and laminated member - Google Patents

Description

  The present invention relates to a method for manufacturing a projected capacitive coupling input device arranged on a display device such as a liquid crystal display, and a substrate with a conductive film and a laminated member used therefor.

  A touch panel is widely used as an input means (input device) of a display device such as a liquid crystal display or an organic EL panel. The touch panel is arranged on the display surface of the display device, thereby enabling extremely direct input with respect to display contents. Therefore, the touch panel needs to transmit the display content of the display device without deterioration in image quality, and transparency is an important factor.

  The main input method of the touch panel is roughly classified into a method for detecting a change in light and a method for detecting a change in electrical characteristics. Among these methods, a resistance film method and a capacitive coupling method are known as methods for detecting a change in electrical characteristics. Furthermore, there are two types of capacitive coupling methods, a surface type and a projection type. There is a method. In particular, the projection type is attracting attention from the viewpoint of being suitable for multi-touch recognition (multi-point recognition), which has become an indispensable function for smartphones and the like.

  Conventionally, the projection type touch panel in the capacitive coupling method generally uses two film base materials on which pattern electrodes having a predetermined shape are formed, as described in Patent Documents 1 and 2, etc. It is made by bonding. A display device provided with a touch panel, such as a tablet-type portable terminal in recent years, has been remarkably progressed in thickness reduction, and there is a strong demand for improvement in optical characteristics as well as thickness reduction in the touch panel. However, since two film base materials are bonded together, it is considered unsuitable for thinning, and there is a limit to making the film base material thin in consideration of handling properties (handling properties). In addition, if the thickness increases due to the lamination of the film base material, the transmittance of the image light from the display device is reduced by that amount, which may deteriorate the image quality of the image displayed by the display device. .

  Therefore, for example, as described in Patent Documents 3 and 4 and the like, a method of obtaining a touch panel by providing capacitive coupling electrodes on both surfaces of a film substrate has been proposed. However, taking into account the formation of electrodes on both sides of the film substrate, the film substrate itself must still have a certain thickness. On the other hand, as in Patent Document 5, for example, a transparent conductive film is formed on a substrate, a pattern electrode is formed by etching, an insulating film is further provided, and then the formation and etching of the transparent conductive film are repeated again. A method of forming a pattern electrode has been proposed. However, such a method requires the above steps to be performed in sequence, so that it is difficult to say that the method is excellent in productivity and the manufacturing cost increases.

JP-A-4-264613 JP 2008-152640 A JP 2010-238052 A JP 2011-154442 A JP 2010-33478 A

  A touch panel as an input device is indispensable for portable terminals such as smartphones that have been rapidly spread and expanded in recent years. And with the thinning of the portable terminal, the touch panel is also strongly demanded to be thin, to improve the optical characteristics, and to reduce the price. However, in the conventional method as described above, when the thickness of the film substrate used for the touch panel is further reduced, not only the handling property is deteriorated but also it is difficult to accurately form the predetermined pattern electrode. Or, in some cases, may cause cracks or tears during production, which may cause problems in production. For this reason, it is difficult to further reduce the thickness by conventional touch panel manufacturing methods.

  Therefore, as a result of diligent research on thinning the touch panel, which is a projected capacitive coupling input device, the present inventors have used an input device using a polyimide laminate that can be peeled off at the interface between polyimide layers. In the process of forming the laminated structure of the present invention, by separating and removing a part of the polyimide layer, it has been found that a thin input device can be produced while solving all of the handling problems and production problems, etc. Was completed.

  Therefore, an object of the present invention is to provide a method capable of efficiently manufacturing a thin input device.

  Another object of the present invention is to provide a substrate with a conductive film and a laminated member that are used to efficiently manufacture a thin input device.

  That is, the present invention is a method for manufacturing a projection capacitive coupling input device disposed on a display device such as a liquid crystal display, and is a transparent conductive pattern patterned on one side of a heat-resistant substrate having heat resistance. When an input device is manufactured by annealing two conductive film-coated substrates provided with a film and then laminating them on a display device via a transparent adhesive layer, the heat-resistant substrate in at least one conductive film-coated substrate Is composed of a polyimide laminate having a first polyimide layer disposed on the transparent conductive film side and a second polyimide layer disposed on the back side of the first polyimide layer, and the polyimide laminate is In the process of laminating the substrate with the conductive film, the input includes a step of separating and removing the second polyimide layer side at the interface between the first and second polyimide layers and thinning the input. It is a method of manufacturing location.

  Moreover, this invention is a board | substrate with an electrically conductive film used for said method, Comprising: The 1st polyimide layer distribute | arranged to the transparent conductive film side, and the 2nd distribute | arranged to the back side of this 1st polyimide layer A heat-resistant substrate made of a polyimide laminate having a polyimide layer, and can be thinned by separating and removing the second polyimide layer at the interface between the first and second polyimide layers. It is a board | substrate with the electrically conductive film for input device formation.

  Furthermore, the present invention is characterized in that after using each of the two substrates with conductive films, annealing is performed, and then the transparent conductive layers are bonded to face each other through the transparent adhesive layer. It is a laminated member for forming an input device.

  In the present invention, after annealing the two conductive film-coated substrates having the transparent conductive film patterned on one side of the heat-resistant substrate having heat resistance, these are laminated on the display device via the transparent adhesive layer. When manufacturing a projected capacitive coupling input device, at least one of the substrates with a conductive film, preferably both of the substrates with a conductive film, as the heat resistant substrate, the first polyimide layer and the second A polyimide laminate having a polyimide layer is used to reduce the thickness of the input device during the lamination process. That is, the polyimide laminate used as the heat-resistant substrate in the present invention includes a first polyimide layer disposed on the transparent conductive film side and a second polyimide layer disposed on the back side of the first polyimide layer. The second polyimide layer can be separated and removed using the interface between the first polyimide layer and the second polyimide layer.

  Here, in order to be able to separate and remove the second polyimide layer using the interface between the first and second polyimide layers, the polyimide interface is made easy to peel off. There is a need. As the means, it is preferable to use a polyimide having a specific chemical structure in at least one of the first and second polyimide layers.

式中、Ａｒ₁は酸無水物残基である４価の有機基を表し、Ａｒ₂はジアミン残基である２価の有機基であり、耐熱性の観点から、Ａｒ₁、Ａｒ₂の少なくとも一方は、芳香族残基であるのが望ましい。 Generally, a polyimide is obtained by polymerizing a raw acid anhydride and a diamine, and can be represented by the following general formula (1).

In the formula, Ar ₁ represents a tetravalent organic group which is an acid anhydride residue, Ar ₂ is a divalent organic group which is a diamine residue, and from the viewpoint of heat resistance, Ar ₁ and Ar ₂ are at least One is preferably an aromatic residue.

このような繰返し構造単位のうち、より好ましくは、下記繰り返し構造単位を有するポリイミドである。

As the polyimide (polyimide resin) suitably used for the first and / or second polyimide layer in the present invention, for example, a polyimide having the following repeating structural unit can be mentioned, and among them, the second polyimide can be used. It is preferred that the layer has such repeating structural units.

Of such repeating structural units, a polyimide having the following repeating structural units is more preferable.

  In the present invention, the second polyimide layer side is finally separated, and the remaining first polyimide layer side constitutes the input device. That is, the second polyimide layer serves as an auxiliary material that supports and protects the first polyimide layer in the process of forming the input device having a laminated structure. For this reason, it is preferable that the handleability as a substrate with a conductive film can be ensured and that the substrate has heat resistance and dimensional stability against annealing. If it is a polyimide which has the above repeating structural units, a glass transition temperature (Tg) can form a heat-resistant polyimide surface with 300 degreeC or more, and isolation | separation in the interface with a 1st polyimide layer is easy. can do. As will be described later, when the second polyimide layer is formed by a casting method, the surface of the second polyimide layer forming the interface between the first and second polyimide layers has a surface roughness (Ra). Is preferably 100 nm or less.

On the other hand, the first polyimide layer that is a component constituting the input device is required to have high transparency as well as heat resistance that can withstand annealing treatment. Therefore, it is preferable to use fluorine-containing polyimide. Here, the fluorine-containing polyimide means one having a fluorine atom in the polyimide structure, and has a fluorine-containing group in at least one component of an acid anhydride and a diamine which are polyimide raw materials. As such a fluorine-containing polyimide, for example, among those represented by the general formula (1), Ar _{1 in} the formula is a tetravalent organic group, and Ar ₂ is represented by the following general formula (2) or (3 ) Represented by a divalent organic group represented by:

R _{1 to} R ₈ in the general formula (2) or the general formula (3) are each independently a hydrogen atom, a fluorine atom, an alkyl group or an alkoxy group having 1 to 5 carbon atoms, or a fluorine-substituted hydrocarbon group. In the general formula (2), at least one of R _{1 to} R ₄ is a fluorine atom or a fluorine-substituted hydrocarbon group, and in the general formula (3), R _{1 to} R _8. At least one of them is a fluorine atom or a fluorine-substituted hydrocarbon group. Among these, preferred specific examples of R _{1 to} R ₈ include —H, —CH ₃ , —OCH ₃ , —F, —CF _{3, and the} like. At least in Formula (2) or Formula (3), One substituent is preferably either —F or —CF ₃ .

Specific examples of Ar ₁ in the general formula (1) when forming the fluorine-containing polyimide include, for example, the following tetravalent acid anhydride residues.

In addition, when forming fluorine-containing polyimide, a specific diamine that gives Ar ₂ in the general formula (1) in consideration of improving the transparency of the polyimide and the releasability from the second polyimide layer. Preferred examples of the residue include the following. That is, good peelability can be exhibited even at the interface with a polyimide having another structure other than the fluorine-containing polyimide, and preferably the adhesive strength at the interface between the first polyimide layer and the second polyimide layer is 1 N / m or more and 500 N / m or less, more preferably 5 N / m or more and 300 N / m or less, and even more preferably 10 N / m or more and 200 N / m or less, so that it can be easily separated by human hands. Is provided. Of course, such a fluorine-containing polyimide may be used as the second polyimide layer, and in that case, the peelability at the interface between the first and second polyimide layers is further improved.

In such a fluorine-containing polyimide, when any one of the structural units represented by the following general formula (4) or (5) is contained in a proportion of 80 mol% or more, transparency and releasability Further, it is more preferable because of its low thermal expansion and excellent dimensional stability. That is, if it is a polyimide which has a structural unit represented by the following general formula (4) or (5), it can be set as a polyimide layer whose thermal expansion coefficient is 25 ppm / K or less, Preferably it is 10 ppm / K or less. In addition, the polyimide having these structural units exhibits a glass transition temperature (Tg) of 300 ° C. or higher, and a transmittance in the wavelength region of 440 nm to 780 nm is 70% or higher, preferably 80% or higher. Therefore, it is more advantageous to form an input device.

  Here, when the polyimide is a polyimide according to the structure of the general formula (4) or (5), other polyimides that may be added at a ratio of less than 20 mol% at the maximum other than the polyimide are particularly limited. In general, general acid anhydrides and diamines can be used. Among these, acid anhydrides preferably used include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 1,4-cyclohexanedicarboxylic acid, 1,2,3 , 4-cyclobutanetetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, and the like. On the other hand, diamines include 4,4'-diaminodiphenylsulfone, trans-1,4-diaminocyclohexane, 4,4'-diaminocyclohexylmethane, 2,2'-bis (4-aminocyclohexyl) -hexafluoro. Examples include propane and 2,2′-bis (trifluoromethyl) -4,4′-diaminobicyclohexane.

  Various polyimides as described above can be obtained by imidizing polyamic acid. Here, the polyamic acid resin solution is preferably obtained by using substantially equal moles of diamine and acid dianhydride as raw materials and reacting them in an organic solvent. More specifically, it is obtained by dissolving diamine in an organic polar solvent such as N, N-dimethylacetamide under a nitrogen stream, adding tetracarboxylic dianhydride, and reacting at room temperature for about 5 hours. Can do. The weight average molecular weight of the obtained polyamic acid is preferably 10,000 to 300,000 from the viewpoint of uniform film thickness during coating and mechanical strength of the resulting polyimide film. In addition, the preferable molecular weight range of a polyimide layer is also the same molecular weight range as a polyamic acid.

  Although there is no restriction | limiting in particular about the means to obtain the polyimide laminated body which has the 1st and 2nd polyimide layer, Since continuous manufacture is possible, the elongate polyimide film which forms a 2nd polyimide layer previously is used. It is preferable to use a casting method in which a polyamic acid resin solution for forming the first polyimide layer is applied while being prepared and conveyed by a roll-to-roll process. After applying the polyamic acid resin solution that forms the first polyimide layer, the long polyimide film of the second polyimide layer is heat-treated at about 150 to 160 ° C. to remove the solvent contained in the resin solution. Further, the polyamic acid is imidized by heat treatment at a higher temperature. The heat treatment performed at the time of imidation may be performed continuously or stepwise from a temperature of about 160 ° C. to a temperature of about 350 ° C., for example.

  As described above, since the second polyimide layer does not directly constitute the input device, the thickness can be appropriately set in consideration of improving the handleability as a substrate with a conductive film. Generally, a thickness of about 100 μm is particularly inconvenient in production, such as when a predetermined pattern electrode is formed on the surface of the first polyimide layer, or a substrate with a conductive film is bonded via a transparent adhesive layer. There is no. Of course, the second polyimide layer may be made thicker, or the second polyimide layer itself may be made thinner by using a copper foil or glass on the back side. Good. On the other hand, the thickness of the first polyimide layer can be made thinner because the second polyimide layer side serves as an auxiliary material. That is, in general, when handling a film, a thickness of about 100 μm is required. However, in the present invention, the second polyimide layer plays a role, so the first polyimide layer should have a thickness of 50 μm or less. It is possible to reduce the thickness to 3 to 50 μm.

  In obtaining a set of substrates with conductive films, first, a patterned transparent conductive film is formed on one side of a heat-resistant substrate. In that case, about at least one board | substrate with a conductive film, the polyimide laminated body which has the above 1st and 2nd polyimide layers is used as a heat resistant board | substrate. When a heat-resistant substrate other than the polyimide laminate is used, for example, a transparent material such as glass and the like having heat resistance that can withstand the annealing process may be used. In order to obtain a thin input device, the thickness is preferably about 20 to 100 μm. However, in order to obtain a thinner input device, both heat-resistant substrates are made of a polyimide laminate as referred to in the present invention. Preferably there is.

  To obtain a patterned transparent conductive film, for example, after forming a transparent conductive film such as ITO (tin-doped indium oxide), SnO, ZnO, or IZO on one surface of a heat-resistant substrate, a weak acid or the like is used. The transparent conductive film as described above may be formed by using a resist pattern formed on one surface of the heat resistant substrate as a mask. Further, these transparent conductive films can be formed on a heat resistant substrate by an electron beam vapor deposition method, a sputter vapor deposition method, a physical vapor deposition method, a screen printing method using a conductive paste material, or the like. The thickness of the transparent conductive film is about 70 nm or less, and the thickness is not particularly limited. However, considering the formation of a thin input device, it is desirable to form the transparent conductive film with a thickness of about 10 to 50 nm.

  The case where ITO is formed as a transparent conductive film by sputtering deposition will be described below as an example. The deposited ITO film is in an amorphous state and has a higher resistance value than the crystalline state. Therefore, the substrate with the conductive film provided with the patterned transparent conductive film is annealed to crystallize the transparent conductive film, and the resistance is lowered to form a patterned electrode. Here, with respect to the pattern electrode shape, that is, the patterning of the transparent conductive film, a plurality of electrode portions are arranged with a predetermined interval in each direction on each substrate with a conductive film, and one set By stacking the conductive film-coated substrates, it is sufficient that the arrangement direction of the electrode portions in the upper and lower two layers intersect with each other so that a projected capacitive coupling type mosaic electrode pattern is provided. .

  The annealing temperature varies depending on the type of the transparent conductive film, and can be set as appropriate. For example, in the case of ITO, it is generally preferable to perform the annealing at about 200 to 250 ° C. In other words, in the present invention, the heat resistance of the heat-resistant substrate means that it can withstand an annealing process for crystallizing the transparent conductive film. As for the polyimide laminate, any polyimide that forms the first and second polyimide layers described above has a glass transition temperature (Tg) higher than the temperature of these annealing treatments, so that it has sufficient heat resistance. have.

  The pair of annealed substrates with conductive films are stacked on a display device through a transparent adhesive layer to form an input device. In that case, after preliminarily pasting the substrates with the conductive film to form a laminated member for forming the input device, the input device may be obtained by pasting again to the display device through the transparent adhesive layer, Alternatively, the input device may be obtained by sequentially bonding two substrates with conductive films to the input device (or to a transparent protective plate described later). Here, there is no restriction | limiting in particular about a transparent contact bonding layer, For example, it may consist of transparent adhesives, such as an acryl type and an epoxy type, or a transparent adhesive sheet is used, or a transparent insulating sheet is used as two conductive materials. You may make it interpose between a board | substrate with a film | membrane, and may make it bond together using a transparent adhesive agent. From the viewpoint of obtaining an input device with a thin laminated structure, the thickness of the transparent adhesive is preferably thin, but the thickness is not particularly limited, and a transparent adhesive layer of about 10 to 50 μm is formed using the transparent adhesive. It is preferable to do this. Note that the transparent adhesive layer is formed using a transparent adhesive, a transparent adhesive sheet, or the like after the transparent conductive film is annealed, so there is no need to consider heat resistance against the anneal treatment. . Moreover, about the transparent adhesive agent, transparent adhesive sheet, etc. which are used in the lamination | stacking process of an input device, the same thing may be used, respectively, and 2 or more types may be combined.

  In the case of previously laminating substrates with conductive films to form a laminated member, preferably, the substrates with two conductive films are bonded through the transparent adhesive layer with the transparent conductive film side facing each other. It is good to make it. Then, the laminated member is bonded to the display surface side of the display device through the transparent adhesive layer. At this time, both the substrates with the conductive film are provided with a heat resistant substrate made of a polyimide laminate. For example, after the second polyimide layer is separated and removed from either polyimide laminate, the first polyimide layer side is bonded to the display device. When only one substrate with a conductive film uses a heat resistant substrate made of a polyimide laminate, the second polyimide layer is separated from the polyimide laminate and removed, and then the first polyimide layer side is removed. It may be bonded to the display device, or the heat-resistant substrate side that is not a polyimide laminate may be bonded to the display device, and then the second polyimide layer on the outermost surface may be separated and removed.

  In addition, when laminating a substrate with a conductive film sequentially on an input device, the substrate with the conductive film is bonded through a transparent adhesive layer with the transparent conductive film side facing the display device. The transparent conductive film side of the other substrate with a conductive film may be bonded via a layer, or the substrate with a conductive film is bonded via a transparent adhesive layer with the heat-resistant substrate side facing the display device. Furthermore, the transparent conductive film side of the other conductive film-attached substrate may be bonded via a transparent adhesive layer. At this time, when both of the substrates with the conductive film are provided with a heat-resistant substrate made of a polyimide laminate, first, the substrate with the conductive film is bonded with the transparent conductive film side facing the display device. It is preferable that the polyimide layer is separated and removed, and then the second polyimide layer is separated and removed after the transparent conductive film side of the other conductive film-attached substrate is bonded. When only one substrate with a conductive film uses a heat-resistant substrate made of a polyimide laminate, first, the substrate with the conductive film is bonded with the heat-resistant substrate side facing the display device, and then the other conductive It is preferable that the second polyimide layer is separated and removed after the transparent conductive film side of the substrate with the film is bonded.

  In the case where two substrates with conductive films are sequentially laminated and stacked, instead of the input device, the object to be attached to the substrate with conductive film to be attached first may be a transparent protective plate. That is, the input device may be provided with a transparent protective plate made of tempered glass, an acrylic plate or the like on the surface for the purpose of protecting it from external impact or various damages. For this reason, preferably, first, the transparent conductive film side is directed to the transparent protective plate, and a conductive film-containing substrate provided with a heat-resistant substrate made of a polyimide laminate is bonded through a transparent adhesive layer, The two polyimide layers are separated and removed. Then, the transparent conductive film side of the other conductive film-attached substrate is bonded to the first polyimide layer via the transparent adhesive layer, and these are further bonded to the display device via the transparent adhesive layer. An input device including a transparent protective plate can be obtained. Here, if the other substrate with a conductive film is also provided with a heat-resistant substrate made of a polyimide laminate, the second polyimide layer may be separated before being bonded to the display device side. Alternatively, the other substrate with the conductive film may be bonded to the display device first, and may be overlapped with the first polyimide layer of the substrate with the conductive film bonded to the transparent protective plate side.

  As described above, when the substrate with the conductive film having the polyimide laminate is bonded to the other conductive film-attached substrate or the display device or the transparent protective plate, the interface between the first and second polyimide layers is obtained. By including the step of thinning in the process of laminating the substrate with the conductive film having the polyimide laminate, the second polyimide layer side is separated and removed by using the thin film, the thin input device can be efficiently Can be manufactured. In particular, if each of the two conductive film-coated substrates includes a heat-resistant substrate made of a polyimide laminate, for example, the first polyimide layer has a thickness of 20 μm, the transparent conductive film has a thickness of about 50 nm, and a transparent adhesive layer. The input device having a total thickness of 100 μm or less can be easily obtained so that the total thickness is about 90 μm.

  ADVANTAGE OF THE INVENTION According to this invention, a thin input device can be manufactured efficiently, solving the fall of handling property, the problem on production, etc.

FIG. 1 is a schematic view showing an example of a polyimide laminate according to the present invention. FIG. 2 is a schematic cross-sectional view of a substrate with a conductive film in which a transparent conductive film patterned on a polyimide laminate is formed. FIG. 3 is a schematic diagram showing a roll-to-roll apparatus for forming a transparent conductive film on a long roll-shaped polyimide laminate. FIG. 4 is a schematic plan view when a projected capacitively coupled touch panel (input device) is formed by stacking a pair of substrates with conductive films. FIG. 5 is a schematic plan view showing a state of one pattern electrode or the like formed on the polyimide laminate. FIG. 6 is a schematic plan view showing a state of the other pattern electrode or the like formed on the polyimide laminate. FIG. 7 is a cross-sectional view taken along the line aa ′ of FIG. 8 is a cross-sectional view taken along line bb ′ of FIG. FIG. 9 is a cross-sectional view of a laminated member for forming an input device according to the present invention. FIG. 10 is a schematic diagram showing a state of thinning when the input device is laminated on the display device using the input device forming laminated member. FIG. 11 is a cross-sectional view of a laminated member for forming an input device in which a transparent insulating sheet is interposed between two substrates with a conductive film. FIG. 12 is a cross-sectional view of a substrate with a conductive film provided with a patterned electrode used in another example. FIG. 13: is sectional drawing of the board | substrate with a electrically conductive film provided with the pattern electrode used in another Example. FIG. 14 is a schematic diagram showing a state of thinning when an input device having a transparent protective plate is obtained.

  Hereinafter, the present invention will be specifically described with reference to the drawings. The present invention is not limited to these contents.

  First, the abbreviations of raw material monomers and solvents used in the synthesis of polyimide and the measurement methods and conditions for various physical properties in the examples are shown below.

[About abbreviations]
DMAc: N, N-dimethylacetamide PDA: 1,4-phenylenediamine TFMB: 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl DADMB: 4,4′-diamino- 2,2′-dimethylbiphenyl, 1,3-BAB: 1,3-bis (4-aminophenoxy) benzene, BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 6FDA: 2 , 2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride-PMDA: pyromellitic dianhydride

[Surface roughness (Ra)]
Surface observation was performed in a tapping mode using an atomic force microscope (AFM) “Multi Mode 8” manufactured by Bruker. Observation of a 10 μm square field of view was performed four times, and the average value thereof was obtained. The surface roughness (Ra) represents the arithmetic average roughness (JIS B0601-1991).

[Peel strength]
Peel by T-peeling test method for the interface between the first polyimide layer and the second polyimide layer in the sample obtained by cutting the polyimide laminate into a strip shape with a width of 10 mm using the Toro Seiki Seisakusho R-1 Evaluation was made by measuring the strength.

[Transmissivity (%)]
About the polyimide film (50 mm x 50 mm) which consists of a 1st polyimide layer, the average value of the light transmittance in 440 nm to 780 nm was calculated | required using the U4000 type spectrophotometer.

[Glass transition temperature Tg]
The glass transition temperature of the polyimide film composed of the first polyimide layer was measured as follows. Using a viscoelasticity analyzer (RSA-II, manufactured by Rheometric Science Effy Co., Ltd.), using a sample with a width of 10 mm and applying a 1 Hz vibration while raising the temperature from room temperature to 400 ° C. at a rate of 10 ° C./min. Of the loss tangent (Tan δ).

[Coefficient of thermal expansion (CTE)]
A polyimide film composed of the first polyimide layer is cut into a size of 3 mm × 15 mm, and a constant heating rate (20 ° C./min) is applied from 30 ° C. while applying a 5.0 g load with a thermomechanical analysis (TMA) apparatus. A tensile test was performed in a temperature range of 260 ° C., and a thermal expansion coefficient (× 10 ⁻⁶ / K) was measured from the amount of elongation of the polyimide film with respect to the temperature.

Synthesis Example 1 (Polyimide A)
Under a nitrogen stream, 8.00 g of PDA was dissolved in the solvent DMAc while stirring in a 300 ml separable flask. Then 22.00 g of this solution BPDA was added. Thereafter, the solution was stirred at room temperature for 5 hours to conduct a polymerization reaction, and kept for a whole day and night. A viscous polyamic acid solution was obtained, and it was confirmed that polyamic acid A having a high polymerization degree was produced.

Synthesis Example 2 (Polyimide B)
Under a nitrogen stream, 12.08 g of TFMB was dissolved in the solvent DMAc while stirring in a 300 ml separable flask. Next, 6.20 g of PMDA and 4.21 g of 6FDA were added to this solution. Thereafter, the solution was stirred at room temperature for 5 hours to conduct a polymerization reaction, and kept for a whole day and night. A viscous polyamic acid solution was obtained, and it was confirmed that polyamic acid B having a high polymerization degree was produced.

Synthesis Example 3 (Polyimide C)
Under a nitrogen stream, 13.30 g of TFMB was dissolved in the solvent DMAc while stirring in a 300 ml separable flask. Next, 9.20 g of PMDA was added to this solution. Thereafter, the solution was stirred at room temperature for 5 hours to conduct a polymerization reaction, and kept for a whole day and night. A viscous polyamic acid solution was obtained, and it was confirmed that polyamic acid C having a high polymerization degree was produced.

[Preparation of polyimide laminate I]
After applying the polyamic acid A resin solution obtained in Synthesis Example 1 onto an electrolytic copper foil having a thickness of 18 μm, the solvent was removed by heating and drying at 130 ° C. Next, it is imidized by heat treatment from 160 ° C. to 360 ° C. at a heating rate of about 15 ° C./min, and has a second polyimide layer (surface roughness Ra = 1.3 nm, Tg = 355 ° C.) having a thickness of 25 μm. A copper clad laminate was obtained.

  On the 2nd polyimide layer of the obtained copper clad laminated board, after apply | coating the resin solution of the polyamic acid B obtained by the synthesis example 2 uniformly so that the thickness after hardening may be set to 25 micrometers, it heat-drys at 130 degreeC. The solvent in the resin solution was removed. Next, the first polyimide layer is formed by imidizing the polyamic acid by heat treatment from 160 ° C. to 360 ° C. at a heating rate of about 20 ° C./min, and the polyimide having the first and second polyimide layers A laminate I was obtained. The peel strength at the interface between the first and second polyimide layers in the obtained polyimide laminate I, the transmittance of the obtained transparent polyimide film (first polyimide layer), and the thermal expansion coefficient were measured. The results are shown in Table 1.

[Preparation of polyimide laminate II]
A polyimide film (Kapton H, manufactured by Toray DuPont Co., Ltd .: surface roughness Ra = 70 nm, Tg = 428 ° C.) having a thickness of 25 μm was used as the second polyimide layer, on which the polyamic acid obtained in Synthesis Example 2 was used. The resin solution of B was uniformly applied so that the thickness after curing was 25 μm, and then dried by heating at 130 ° C. to remove the solvent in the resin solution. Next, heat treatment is performed at a temperature increase rate of about 20 ° C./min from 160 ° C. to 360 ° C. to imidize the polyamic acid to form a first polyimide layer, and a polyimide laminate having first and second polyimide layers I got II. The peel strength at the interface between the first and second polyimide layers in the obtained polyimide laminate II, the transmittance of the obtained transparent polyimide film (first polyimide layer), and the thermal expansion coefficient were measured. The results are shown in Table 1.

[Preparation of Polyimide Laminate III]
A polyimide film having a thickness of 25 μm (Upilex S, manufactured by Ube Industries, Ltd .: surface roughness Ra = 15 nm, Tg = 359 ° C.) was used as the second polyimide layer, and the polyamic acid C obtained in Synthesis Example 3 was formed thereon. The resin solution was uniformly applied so that the thickness after curing was 25 μm, and then the solvent in the resin solution was removed by heating and drying at 130 ° C. Next, heat treatment is performed at a temperature increase rate of about 20 ° C./min from 160 ° C. to 360 ° C. to imidize the polyamic acid to form a first polyimide layer, and a polyimide laminate having first and second polyimide layers III was obtained. The peel strength at the interface between the first and second polyimide layers in the obtained polyimide laminate III, the transmittance of the obtained transparent polyimide film (first polyimide layer), and the thermal expansion coefficient were measured. The results are shown in Table 1.

[Evaluation of Separability of Polyimide Laminates I-III]
For the polyimide laminates I to III immediately after production, each polyimide layer was manually separated using the interface between the first and second polyimide layers, and the ease of separation was confirmed. It could be easily separated without damaging the separated polyimide layer and showed good peelability.

[Preparation of Comparative Reference Polyimide Laminate IV]
After uniformly applying the polyamic acid B resin solution obtained in Synthesis Example 2 on an electrolytic copper foil having a thickness of 18 μm so that the thickness after curing is 25 μm, it is dried by heating at 130 ° C. to remove the solvent in the resin solution. Removed. Next, the polyimide layer is formed by imidizing the polyamic acid by heat treatment from 160 ° C. to 360 ° C. at a heating rate of about 20 ° C./min, and a polyimide for comparison and reference comprising a polyimide layer and a copper foil. Laminate IV was obtained. An attempt was made to peel off the polyimide layer from the obtained comparative reference polyimide laminate IV, but the adhesive force at the interface between the polyimide layer and the copper foil was very strong, and the polyimide layer could not be peeled off.

[Example of manufacturing input device]
FIG. 1 shows a long roll-shaped polyimide laminate 10 provided with a first polyimide layer 2 on one surface of a polyimide film forming a second polyimide layer 1. FIG. 2 is a longitudinal sectional view of the conductive film-equipped substrate 20 on which the patterned transparent conductive film 3 is formed on the polyimide laminate 10.

This polyimide laminate 10 can be obtained as follows, for example, in accordance with the above-described example of producing the polyimide laminate III.
First, a commercially available polyimide film having a thickness of 25 μm wound as a roll to form the second polyimide layer 1 (Upilex S, manufactured by Ube Industries, Ltd .: surface roughness Ra = 15 nm, Tg = 359 ° C.) Prepare. Then, by a roll-to-roll process, a polyamic acid C resin solution to be the first polyimide layer 2 synthesized in advance on this polyimide film is applied so that the thickness after curing is 25 μm, and then 130 ° C. The solvent in the resin solution is removed by drying with heating. Next, heat treatment is performed at a temperature increase rate of about 20 ° C./min from 160 ° C. to 360 ° C. to imidize the polyamic acid, and then cooled to room temperature, the second polyimide layer 1 is formed on the back side of the first polyimide layer 2. Can be obtained.

  FIG. 3 shows an example of a roll-to-roll apparatus for forming a transparent conductive film on the long roll-shaped polyimide laminate 10. As shown in FIG. 3, the roll-shaped polyimide laminate 10 is held by the feeding mechanism 120, the winding mechanism 130, the feeding-side roll winding mechanism 140, and the winding-side roll winding mechanism 150. A transparent conductive film 3 is formed by means such as vapor deposition. Here, when laminating the transparent conductive film in a process that requires a vacuum environment such as vapor deposition, the entire roll-to-roll apparatus is installed in a vacuum chamber and processed.

  Moreover, in obtaining the patterned transparent conductive film 3, after forming the transparent conductive film, it may be etched into a predetermined shape using weak acid or the like, or the first layer of the polyimide laminate 10 may be formed. A transparent conductive film may be formed by forming a resist pattern on the polyimide layer side and using it as a mask. After the patterned transparent conductive film 3 is formed, the polyimide laminated body 10 can be annealed to obtain a substrate with a conductive film provided with a patterned electrode. Here, ITO is mentioned as a typical material of a transparent conductive film. Generally, when ITO is deposited, it is in an amorphous state and its resistance value is high. Therefore, if annealing treatment is performed at about 200 ° C. to 250 ° C. after the patterned transparent conductive film 3 is formed, ITO can be crystallized to reduce the resistance value, thereby forming a low resistance pattern electrode. it can. Since the polyimide laminate 10 of the present invention has sufficient heat resistance with respect to such an annealing temperature, annealing is performed in a state where the patterned transparent conductive film 3 is provided to reduce resistance. Can do.

  In the present invention, the polyimide laminate 10 used as a heat resistant substrate is transparent because the first polyimide layer 2 disposed on the transparent conductive film side is low in thermal expansion and has high transmittance in the visible light region. It has excellent dimensional stability, high heat resistance, excellent surface smoothness, and small retardation in the in-plane direction. Further, the second polyimide layer 1 serving as an auxiliary material for supporting and protecting the first polyimide layer 2 can be easily separated at the laminated interface with the first polyimide layer 2. Therefore, the first polyimide layer 2 that finally constitutes the input device can be made to have a thickness of 50 μm or less. In other words, a film with a thickness of about 50 μm is usually too thin, and not only does film elongation in roll-to-roll equipment become a problem, but also handling characteristics in the pattern electrode formation process and input device assembly process. Etc. becomes a problem. However, according to the present invention, even when the patterned transparent conductive film 3 is formed on the surface of the first polyimide layer 2 and annealed to obtain a predetermined pattern electrode, the second polyimide layer 1 coexists. Since it is used as the polyimide laminate 10 to be manufactured, it is difficult to stretch and a state that is easy to handle is secured.

  FIG. 4 is a schematic plan view showing a state of a pattern electrode when a projected capacitively coupled touch panel (input device) 60 is formed by laminating a pair of substrates with conductive films. The touch panel 60 includes one pattern electrode 51 and the other pattern electrode 52, and further includes a signal extraction wiring 31 and an external connection terminal 41 for the pattern electrode 51 and a signal extraction wiring 32 for the pattern electrode 52. And an external connection terminal 42. One pattern electrode 51, signal extraction wiring 31, and external connection terminal 41, and the other pattern electrode 52, signal extraction wiring 32, and external connection terminal 42 are formed on different heat-resistant substrates. In this production example, the polyimide laminate 10 having the second polyimide layer 1 having a thickness of 100 μm and the first polyimide layer 2 having a thickness of 20 μm was used as the heat resistant substrate.

  Among these, FIG. 5 shows a state of one pattern electrode 51 and the like formed on the polyimide laminate 10. FIG. 7 is a cross-sectional view taken along the line aa ′ of FIG. The pattern electrode 51, the signal extraction wiring 31, and the external connection terminal 41 are obtained by etching a 40 nm thick transparent conductive film formed on the surface of the first polyimide layer 2 of the polyimide laminate 10. The diamond-shaped electrode portions are arranged at predetermined intervals in one direction through the signal extraction wiring 31. Further, FIG. 6 shows a state of the other pattern electrode 52 and the like formed on the polyimide laminate 10, and a bb ′ cross-sectional view of FIG. 6 is FIG. The pattern electrode 52, the signal extraction wiring 32, and the external connection terminal 42 shown in FIG. 6 are obtained by etching a transparent conductive film having a film thickness of 40 nm, as in FIG. The portions are arranged with a predetermined interval in one direction through the signal extraction wiring 32. The pattern electrode 52 is finally bonded to the pattern electrode 51 shown in FIG. 5 to form a mosaic electrode pattern of the projected capacitive coupling type as shown in FIG. The electrode 51 is produced so that the arrangement direction of the electrode portions intersects each other.

  The pair of conductive film-coated substrates 20 on which the pattern electrodes 51 and 52 are formed are bonded using a transparent adhesive having an insulating property such as acrylic or epoxy so that the transparent conductive film side faces each other. . FIG. 9 shows a cross-sectional view (cross-section cc ′ in FIG. 4) in which both are bonded. At this time, the second polyimide layer 1 of the polyimide laminate 10 as both heat resistant substrates is not separated but is in the state of a laminated member for forming an input device. Further, in this example, the thickness of the transparent adhesive layer 80 made of the transparent adhesive after bonding was set to 30 μm.

  As shown in FIG. 10, the laminated member for forming the input device obtained as described above was separated from one polyimide laminate 10 to remove the second polyimide layer 1 and thinned, Using a transparent adhesive, it is bonded to a display device (not shown) such as a liquid crystal display device or an organic EL display device. After that, if the second polyimide layer 1 is separated and removed from the other polyimide laminate 10, the input device 60 according to the embodiment of the present invention can be obtained. In this way, if the second polyimide layer 1 on the outermost surface is separated after being bonded to the display device, it can be protected from scratches and dirt, and a thin input device having a total thickness of approximately 70 μm. 60 can be easily obtained with good handling properties.

  FIG. 11 shows a laminated member for obtaining an input device corresponding to a modification of the above embodiment. The difference from the above-described embodiment is that when the two conductive film-attached substrates 20 are bonded together, a transparent insulating sheet (dielectric) 90 is interposed between the pattern electrodes and bonded using a transparent adhesive. It is a point. In this way, there is an advantage that the spacing between the upper and lower two-layer mosaic electrode patterns can be kept more uniform. In the modification shown in FIG. 11, the transparent insulating sheet 90 having a thickness of 15 μm is used. However, in the present invention, the polyimide laminate 10 is used as a heat-resistant substrate. The thickness can be suppressed to 100 μm or less.

  12 to 14 are schematic cross-sectional views according to another embodiment when manufacturing an input device arranged on a display device. The difference from the above-described embodiment is that the procedure for bonding the two conductive film-attached substrates is different. Until the polyimide laminate 10 provided with the pattern electrode 51 and the like and the polyimide laminate 10 provided with the pattern electrode 52 and the like are obtained, the process is the same as in the previous embodiment. 12 is a cross-sectional view (c-c ′ cross-section of FIG. 4) of the conductive film-equipped substrate 20 provided with the pattern electrode 52 and the like, and FIG. FIG. 14 is a schematic cross-sectional view showing a state in which these conductive film-attached substrates 20 are sequentially bonded to the transparent protective plate 100. FIG.

  Here, first, the transparent conductive film side of the substrate with conductive film 20 provided with the pattern electrode 52 is bonded to the transparent protective plate 100 made of tempered glass having a thickness of 500 μm using a transparent adhesive. Next, the second polyimide layer 1 is separated and removed from the bonded polyimide laminate 10 of the conductive film-attached substrate 20 to reduce the thickness. Next, the transparent conductive film side of the substrate with conductive film 20 provided with the pattern electrode 51 is attached to the first polyimide layer 2 exposed by peeling off the second polyimide layer 1 using a transparent adhesive. Match. And after separating and removing the 2nd polyimide layer 1 from the polyimide laminated body 10 of this board | substrate 20 with an electrically conductive film and making it thin, it uses a transparent adhesive again, and is bonded to a display apparatus, and is transparently protected. An input device 60 having a plate can be obtained. In the case of this example, the thickness of each transparent adhesive layer 80 made of the transparent adhesive after bonding was set to 20 μm.

  In this way, the input device 60 provided with the transparent protective plate can be obtained, and the first polyimide layer 2 is present between the pattern electrodes. Therefore, as shown in the previous modification example Without using a transparent insulating sheet, the spacing between the upper and lower two-layer mosaic electrode patterns can be kept more uniform.

  As described above, in the present invention, at least one substrate 20 with a conductive film is provided with a heat-resistant substrate made of the polyimide laminate 10 as described above, and preferably both substrates with a conductive film are polyimide laminates. The input device is formed by laminating a pair of the conductive film-containing substrates 20 after the annealing treatment on the display device through the transparent adhesive layer so that the heat-resistant substrate made of 10 is provided. In that case, in the lamination process of the board | substrate 20 with the electrically conductive film provided with the polyimide laminated body 10, the handling property in manufacture of an input device is ensured by isolate | separating and removing the 2nd polyimide layer 1 from the polyimide laminated body 10. FIG. However, a reduction in thickness can be achieved at the same time.

DESCRIPTION OF SYMBOLS 1 2nd polyimide layer 2 1st polyimide layer 3 Transparent conductive layer 10 Polyimide laminated body 20 Substrate with conductive film 31, 32 Signal extraction wiring 41, 42 External connection terminal 51, 52 Pattern electrode 60 Touch panel (input device)
DESCRIPTION OF SYMBOLS 80 Transparent adhesive layer 90 Transparent insulator (dielectric) sheet | seat 100 Transparent protective plate 110 Process processing part 120 Sending mechanism 130 Winding mechanism 140 Sending side roll winding mechanism 150 Winding side roll winding mechanism

Claims (14)

A method of manufacturing a projected capacitive coupling input device arranged on a display device such as a liquid crystal display,
After annealing the two conductive film-provided substrates provided with the transparent conductive film patterned on one side of the heat-resistant substrate having heat resistance, these are laminated on the display device through the transparent adhesive layer to form the input device. When manufacturing
The heat-resistant substrate in at least one of the substrates with a conductive film had a first polyimide layer disposed on the transparent conductive film side and a second polyimide layer disposed on the back side of the first polyimide layer. In the process of laminating a substrate with a conductive film having a polyimide transition body, the first polyimide layer having a glass transition temperature higher than the annealing temperature, and the polyimide lamination body, A method for manufacturing an input device, comprising: a step of separating and removing the second polyimide layer side at the interface of the polyimide layer to reduce the thickness.   After bonding the two conductive film-attached substrates through the transparent adhesive layer so that the transparent conductive film sides face each other, the second polyimide layer is separated and removed from the conductive film-containing substrate having the polyimide laminate. The method of manufacturing an input device according to claim 1.   3. The input according to claim 2, wherein each of the two substrates with conductive films includes a heat-resistant substrate made of a polyimide laminate, and after the two are bonded together, the respective second polyimide layers are separated and removed. Device manufacturing method.   The method for manufacturing an input device according to claim 2 or 3, wherein a transparent insulating sheet is interposed between two substrates with a conductive film, and the substrates are bonded together.   After the transparent conductive film side is directed to the display device and the substrate with the conductive film including the heat-resistant substrate made of the polyimide laminate is bonded through the transparent adhesive layer, the second polyimide layer is separated and removed. The method for manufacturing an input device according to claim 1, wherein the transparent conductive film side of the other conductive film-attached substrate is bonded through a transparent adhesive layer.   After the transparent conductive film side is directed to the transparent protective plate and the substrate with the conductive film including the heat resistant substrate made of the polyimide laminate is bonded through the transparent adhesive layer, the second polyimide layer is separated and removed. Further, the transparent conductive film side of the other conductive film-attached substrate is bonded through a transparent adhesive layer, and further bonded to the display device through the transparent adhesive layer to obtain an input device provided with a transparent protective plate. The method of manufacturing an input device according to claim 1.   Each of the two substrates with a conductive film includes a heat-resistant substrate made of a polyimide laminate, and after the transparent conductive film side of the other substrate with a conductive film is bonded, the second polyimide layer is separated and removed. The manufacturing method of the input device of Claim 5 or 6.   The method for manufacturing an input device according to claim 1, wherein an adhesive strength at an interface between the first and second polyimide layers is 1 N / m or more and 500 N / m or less.   The method for manufacturing an input device according to claim 1, wherein the first polyimide layer is made of fluorine-containing polyimide and has a transmittance of 70% or more in a wavelength region of 440 nm to 780 nm.   The method for manufacturing an input device according to claim 9, wherein the first polyimide layer has a thermal expansion coefficient of 25 ppm / K or less.   The surface of the second polyimide layer forming the interface between the first and second polyimide layers has a surface roughness (Ra) of 100 nm or less and a glass transition temperature (Tg) of 300 ° C. or more. The manufacturing method of the input device in any one of Claims 1-10 which have these. The method for manufacturing an input device according to claim 11, wherein the second polyimide layer is made of polyimide having the following structural unit.

  It is a board | substrate with an electrically conductive film used for the method in any one of Claims 1-12, Comprising: It distribute | arranges to the 1st polyimide layer distribute | arranged to the transparent conductive film side, and the back side of this 1st polyimide layer. A heat-resistant substrate made of a polyimide laminate having a second polyimide layer, and can be thinned by separating and removing the second polyimide layer at the interface between the first and second polyimide layers. A substrate with a conductive film for forming an input device.   An input comprising: using the two substrates with conductive films according to claim 13 and performing an annealing process, and then bonding the transparent conductive films so that the transparent conductive film sides face each other through a transparent adhesive layer. Device forming laminated member.

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