JP5434242B2 - Flexible electronic circuit board, method for manufacturing the same, and image display device - Google Patents

Description

The present invention relates to an electronic circuit substrate such as an organic thin film transistor element in which an electronic circuit having an organic semiconductor layer is laminated on a flexible substrate, and in particular, has excellent connection terminal portion strength and reliable electrical continuity with an external circuit substrate. The present invention relates to an electronic circuit board.
The present invention is applicable to an electronic circuit board formed on a plastic substrate.

  In recent years, electro-optical display devices such as liquid crystal displays, organic electroluminescence (hereinafter also referred to as organic EL) displays, and electrophoretic displays have been developed. For example, a liquid crystal device has a structure in which a substrate on which a thin film transistor is formed is used as a drive circuit, and a flexible printed circuit (FPC) on which a driver IC for driving a liquid crystal panel is mounted is connected thereto. ing.

  In such a conventional liquid crystal display panel, an amorphous silicon TFT (Thin Film Transistor) element or the like is formed on a glass substrate by a photolithography method or an etching method to serve as a display region driving element, and the display region has a frame. In order to reduce mounting damage to the electrode wiring of the arranged terminal portion, the electrode wiring has been covered with a protective film (see, for example, Patent Document 1 and Patent Document 2). For this reason, various mounting forms such as COG mounting, COF mounting, TCP mounting, and TAB mounting can be set as mounting forms of the driver IC on the display.

  By the way, printable electronics, in which an organic material is made into a solution and an electrode, an insulating layer, and a semiconductor layer are formed by a printing technique to produce an electronic circuit, has attracted attention, and the realization of a flexible electronic element such as a bent solar cell or electronic paper is expected. Has been. By using printing technology, materials can be used with high efficiency, so electronic circuits can be manufactured at low cost and low environmental impact. However, how to suppress damage to organic materials when mounting driver ICs? Is a problem. In other words, if an FPC board can be connected without damage to an electronic circuit board made of an organic material system that is not directly applicable to the prior art, a system design that can be connected to a conventional driver IC or power supply circuit becomes possible. Become.

  Here, for example, in an organic TFT element formed on a plastic substrate that is considered to be promising as a display drive circuit such as electronic paper, it is necessary to mount an FPC substrate on the terminal portion and connect it to a driver IC or a power supply circuit. In the FPC board mounting, a process at a low temperature and a low load is a problem. In an electronic circuit including an organic semiconductor layer, the conventional photolithography method or etching method has a large load on the material, which causes a problem because the terminal portion is damaged. In addition, the conventional sintering type ink or paste has a problem that since the sintering temperature rises to several hundred degrees, an electronic circuit board using a plastic substrate has insufficient heat resistance and cannot be used.

  Further, for example, Patent Document 3 and Patent Document 4 disclose organic TFT elements that are printed and formed with various inks (pastes) in which electrode materials, insulating materials, and semiconductor materials are made into solutions. In these prior arts, an insulating layer formed using an organic resin material to which fine particles are added is used on the electrode wiring of the terminal portion. In this terminal portion, an insulating layer is formed by a printing technique, and a thick film terminal portion is formed in which a mounting electrode for connection is formed on the electrode wiring using a conductive paste. However, when the FPC board is mounted, the mounting electrodes for connecting the terminal portions are disconnected due to application of heat and pressure, and an electric signal from the FPC board cannot be input. That is, there is a problem that the strength of the insulating layer is insufficient. At this time, as the insulating layer is dissolved, anisotropic conductive adhesive (ACF) provided on the FPC board also flows out from both ends of the terminal portion, and the mounting electrode is destroyed by the flow of the insulating layer. There was also the problem of being done.

  By the way, an organic TFT element is formed on a plastic substrate by a method different from a dry process such as a printing technique, and the electrode wiring of the terminal portion is protected with an organic film (for example, Patent Document 5). reference.). Specifically, an organic film is formed on the electrode wiring of the terminal portion, the terminal of the FPC board is positioned on the electrode wiring and the ACF is interposed, and the conductive particles in the ACF penetrate the organic film by thermocompression bonding. Thus, electrical connection between the organic TFT element and the connection terminal of the FPC board can be secured.

  However, the conductive particles need to be disposed with good reproducibility on the electrode wiring through the organic film. Such a method has a problem of process reproducibility, and if too much pressure is applied, not only the electrode but also the plastic substrate is damaged, and there is a problem that the FPC substrate cannot be normally conducted.

  Therefore, in view of the above, it is difficult to mount the FPC board to the terminal part of the electronic circuit formed on the plastic board and to conduct the electricity reliably. For this reason, it becomes impossible to apply a flexible electronic circuit as a drive element.

  The present invention is an invention made to solve the above-described problems in the prior art, such as an organic thin film transistor element in which an electronic circuit including an organic semiconductor is laminated on a flexible substrate such as plastic. It is an object of the present invention to provide a flexible electronic circuit board, a manufacturing method thereof, and an image display device in which the strength of a connection terminal portion is improved and electrical continuity with an FPC board is ensured in an electronic circuit.

In order to solve the above problems, a flexible electronic circuit board, a manufacturing method thereof, and an image display device according to the present invention specifically have the technical features described below .
(1): A flexible electronic circuit board in which a flexible substrate and an electronic circuit including an organic semiconductor layer are stacked on the substrate, and a connection terminal connected to a terminal electrode included in the flexible printed circuit board The connection terminal portion includes an electrode wiring, and an insulating protective film is formed so as to be in contact with the electrode wiring, the insulating protective film including at least a resin binder and an inorganic filler, volume ratio of the resin binder in the protective layer is less than 67% more than 45%, the inorganic filler, and at least inorganic filler a and inorganic filler B, the inorganic filler a, the average particle size P _a is the It is the largest among the inorganic filler, and a mean particle size P _a is 0.3～1Myuemu, the inorganic filler B, the average particle size P _B inorganic filler A smallest of the ratio _P A / _{P B} and the _{P B} and the _{P A} is a flexible electronic circuit board, characterized in that 3 to 25.
( 2 ): The flexible electronic circuit board according to (1), wherein the resin binder is a phenol resin.
( 3 ): The flexible electronic circuit board according to (1) or (2), wherein the inorganic filler is silica.
( 4 ): The flexible printed circuit board and the power supply circuit are connected to the flexible electronic circuit board described in any one of (1) to (3) above, and the display panel is bonded. An image display device characterized by the above.
( 5 ): The method for manufacturing a flexible electronic circuit board according to any one of (1) to (3) , wherein the insulating protective film is formed by a screen printing method. A method for manufacturing a flexible electronic circuit board.

  According to the present invention, in an electronic circuit such as an organic thin film transistor element in which an electronic circuit including an organic semiconductor is stacked on a flexible substrate such as plastic, the strength of the connection terminal portion is improved and the electrical connection with the FPC substrate is improved. A flexible electronic circuit board and a method for manufacturing the same, and an image display device that ensure reliable electrical conduction can be provided.

It is a cross-sectional schematic diagram which shows the structure of the bottom gate type organic TFT element in one Embodiment of the flexible electronic circuit board based on this invention. 1 is a schematic plan view showing a configuration of a bottom gate type organic TFT element in an embodiment of a flexible electronic circuit board according to the present invention. It is the schematic which shows an example of a structure of the electrophoresis type display panel which used the organic TFT element as the drive part. It is the schematic which shows an example of a structure of the electrophoresis type display panel which used the organic TFT element as the drive part. It is the schematic which shows an example of the structure by which the insulating protective film was formed in the electrophoretic display panel which used the organic TFT element as the drive part. It is the schematic which shows an example of the structure by which the mounting electrode was formed in the electrophoresis type display panel which used the organic TFT element as the drive part. It is the schematic which shows an example of a structure of a FPC board. It is a plane schematic diagram which shows an example of a structure of the organic TFT element with which the FPC board | substrate was bonded together. It is a graph which shows the calculation result of the space rate by a two-component particle mixed packed bed space rate estimation program. It is the schematic which shows an example of the arrangement | positioning relationship between the printing squeegee and the screen mesh in one Embodiment of the manufacturing method of the flexible electronic circuit board based on this invention. It is the schematic which shows an example at the time of pattern formation in one Embodiment of the manufacturing method of the flexible electronic circuit board based on this invention.

A flexible electronic circuit board according to the present invention is a flexible electronic circuit board in which a flexible substrate 7 and an electronic circuit including an organic semiconductor layer 6 are laminated on the substrate 7, It has a connection terminal part connected with the terminal electrode 18 with which the board | substrate 20 is provided, and this connection terminal part is equipped with an electrode wiring (4, 5), and an insulating protective film so that it may contact this electrode wiring (4, 5) The insulating protective film 16 includes at least a resin binder and an inorganic filler, and the volume ratio of the resin binder contained in the insulating protective film 16 is 40% to 67%. .
Next, the flexible electronic circuit group according to the present invention will be described in more detail.
Although the embodiments described below are preferred embodiments of the present invention, various technically preferable limitations are attached thereto, but the scope of the present invention is intended to limit the present invention in the following description. Unless otherwise described, the present invention is not limited to these embodiments.
Below, the structure in one Embodiment of the flexible electronic circuit board based on this invention is demonstrated with reference to drawings.

  In the present invention, an insulating protective film 16 is formed on a terminal portion of an electronic circuit using the flexible substrate 7 to protect the connection terminal portion from heat and pressure by a mounting process of a flexible printed circuit (FPC) 20. It is to be. Hereinafter, the structure and durability improvement of the organic TFT (Thin Film Transistor) element 10 and the insulating protective film 16 applied to the connection terminal portion of the element 10 will be described, and a screen printing method as a method of forming the insulating protective film will be described. Will be described.

In order to fabricate an electronic circuit board having a multilayer structure such as the organic TFT element 10 by a dry process such as a printing technique, for example, a configuration as described in Patent Documents 3 and 4 can be employed. When the insulating protective film 16 is formed on the connection terminal portion of the organic TFT element 10, it is premised that the process temperature is unified. When the circuit configuration becomes complicated like a thin film transistor having a multi-layer structure, various materials are used, but these materials have different heat resistance and environmental resistance. At present, the formation of organic semiconductor layers seems to be promising to use inks in which organic compounds that are soluble in organic solvents are dissolved, and vigorous research and development has been conducted to apply such organic semiconductor inks to circuit boards. It is.
However, in the present situation where the heat resistance of the organic semiconductor material is fragile, the process temperature is limited to 200 degrees or less at most. If the process temperature is 200 ° C. or less, a plastic substrate can be used, and a flexible electronic circuit board can be manufactured. In such an electronic circuit board with a limited process temperature, it is necessary to form an insulating protective film that can ensure sufficient mounting resistance at the terminal portion, and it is necessary to select a material.

[Organic TFT element 10]
(About organic TFT element 10)
FIG. 1a is a schematic cross-sectional view showing the configuration of the bottom gate type organic TFT element in the present embodiment, and FIG. 1b is a schematic plan view showing the configuration of the bottom gate type organic TFT element in the present embodiment. As a manufacturing method, a known method can be used. For example, the methods disclosed in Patent Documents 3 and 4 may be used. FIG. 2a is an example of a cross-sectional view of an electrophoretic display panel using an organic TFT element as a drive unit, and FIG. 2b is an example of a plan view of an electrophoretic display panel using an organic TFT element as a drive unit. . First, the structure of the organic TFT element will be described below with reference to FIGS. 1a and 1b.

  In the organic TFT element 10 shown in FIG. 1 b, a gate electrode 1 is provided on a substrate 7 having good insulating properties for the purpose of controlling transistor current, and a gate insulating film is provided so as to cover the gate electrode 1. Thereafter, a source electrode 2 for inputting a signal and a drain electrode 3 are provided on the gate insulating film. Here, the description proceeds with the drain electrode 3 as an output electrode. An active layer (organic semiconductor layer 6, organic semiconductor: OSC = Organic Semiconductor) for controlling the channel of the transistor is provided between and on the source electrode 2 and the drain electrode 3.

(Substrate 7)
The flexible substrate 7 needs to be made of a material and thickness that can support the organic TFT element 10, the display element, the FPC board 20, the driver IC, the external power supply circuit, and the like. The advantage of the printing technique can be maximized because a high-throughput and low-temperature process can be performed at low cost, and it is preferable to use a resin material as the substrate material in consideration of light weight and robustness. Examples of resin materials include PEN (polyethylene naphthalate), PET (polyethylene terephthalate), PC (polycarbonate), polyethersulfone (PES), PI (polyimide), and the like. It is necessary to select in consideration of resistance to dissolution and deformation / degeneration due to thermal processes.

(TFT gate electrode 1, gate insulating film, source electrode 2, drain electrode 3)
A gate electrode 1, a gate selection line 4 extending from the gate electrode 1 for the purpose of controlling transistor current on the flexible substrate, and a gate connection terminal portion at the end of the gate selection line 4 are provided (FIG. 2b). A gate insulating film is provided so as to cover the gate electrode 1 and the gate selection line 4. At this time, the gate insulating film is not formed on the gate connection terminal portion.

(Gate electrode 1)
The material of the gate electrode 1 is not particularly limited as long as it is a conductive material. Platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony, lead, tantalum, indium, aluminum, zinc, magnesium, and These alloys and conductive metal oxides such as indium / tin oxide can be used.
As the manufacturing method, it is preferable to use nano metal ink to form by a known method such as an inkjet method (for example, refer to the method described in Patent Document 4) or other printing methods.

(Gate insulation film)
Examples of the material for the gate insulating film include polyvinylphenol, polyvinyl alcohol, polyvinyl butyral, and polyimide. Using these materials, a spin coating method, a slit coating method, or the like can be used.
When forming the gate insulating film, the gate insulating film is formed except for these regions so that the gate insulating film is not formed on or near the gate selection line corresponding to the connection terminal portion.

(Source / drain electrodes 2, 3)
A source electrode 2 and a drain electrode 3 are provided on the gate insulating film. As these materials, among the conductive substances mentioned as the gate electrode material, those that are ohmic connected at the contact surface with the semiconductor layer are preferable. Here, it is assumed that the drain terminal 3 is an output electrode, and the source terminal portion is formed at the end of the source signal line 5 obtained by extending the source electrode 2.
As a manufacturing method, it is preferable to form by a inkjet method or other printing methods using nano metal ink. In electrode formation by ink-jet coating, the surface energy of the base is changed, and the surface that is easy to adapt to the ink and the surface that is difficult to adapt are lightly processed. Is possible.

(Organic semiconductor layer 6 = active layer)
An organic semiconductor layer for controlling the channel of the transistor is provided between and on the source electrode 2 and the drain electrode 3. As a material for the organic semiconductor layer, a known organic semiconductor material can be used. Particularly, it is easy to produce an organic semiconductor material such as an organic low molecule, an organic polymer, or an organic oligomer that can be applied. Is preferable. Examples of the organic low molecular weight and organic oligomer materials include acene molecular materials including anthracene, tetracene, pentacene and substituted derivatives thereof, metal phthalocyanines, thiophene oligomers and derivatives thereof, fullerene C60, carbon nanotubes and derivatives thereof, and the like.

  Low molecular weight materials such as pentacene are generally formed by vacuum evaporation, but JEAnthonyra et al, Org. Lett. Vol. 4 p15 (2002) and PTHerwig et al, Adv. Mater vol.11 A pentacene film can be formed by chemical change after coating using a precursor of pentacene described in p480 (1999). Ink jet methods are preferred when inks prepared by dissolving these materials in an organic solvent are used. A method of forming a pentacene film by a conventionally known thermal vacuum deposition method may be simple.

[Active matrix drive circuit board]
(Interlayer insulating film 8, pixel electrode 9)
In order to use the organic TFT circuit substrate 10 as a display panel drive circuit, it is necessary to form the pixel electrode 9 on the drain electrode 3. As shown in FIG. 1b, it is necessary to form an interlayer insulating film 8 having a through hole on each drain electrode 3, and then form an individual pixel electrode 9 to be electrically connected to the drain electrode 3 through the through hole. is there. When the pixel electrode 9 is formed in an individual element, a leakage current is generated during high-frequency operation depending on the capacitance between the source electrode 2 and the pixel electrode 9, and thus the capacitance of the interlayer insulating film 8 is small. It is preferable to form a thick film made of a low dielectric constant material.

An arbitrary printing method can be used as a method of forming the interlayer insulating film 8, but in this embodiment, a desired interlayer insulating film shape can be obtained by using a screen printing method.
The screen printing method can easily form a thick film of 1 μm or more compared to the vacuum film forming method and other printing methods, and can be patterned only in a necessary region by a simple process compared to the photolithography method. Therefore, the material use efficiency is high and the throughput is fast, so the productivity is high. In addition, since the surface of the organic TFT element on which the electrode and the insulating film are patterned is uneven, the convenience of the screen printing method is maximized.

  For the formation of the interlayer insulating film 8, screen printing with an insulating paste is preferable. A well-known thing can be used for an insulating paste. In addition, a paste prepared by appropriately blending and kneading materials that have necessary functions may be used, but it is essential that the organic semiconductor layer is not damaged. For this reason, it is preferable to use the interlayer insulation film for suppressing the damage of the organic-semiconductor material of an organic TFT element. As the screen plate, a screen plate that has been exposed and developed so that a through-hole pattern can be formed by applying an emulsion to a screen mesh can be used.

  For example, as the interlayer insulating film 8, a film in which a filler is dispersed in an organic material is used. Examples of the organic material include a resin, and the organic material is not particularly limited as long as it can be dissolved in a solvent used at the time of production, but a phenol resin is preferable. Further, the molecular weight (Mw) of the resin is preferably in the range of 4000 or more, and more preferably in the range of 8000 or more. Further, the polydispersity of the resin is preferably in the range of 5 or less, and more preferably in the range of 3 or less. If the molecular weight of the resin is less than 4000 and the polydispersity is in the range of more than 5, a sufficient value cannot be obtained as the viscosity when pasted, and there is a problem that the through-hole cannot be patterned during printing.

As long as the filler can be present as particles in the interlayer insulating film 8, it may be either organic particles or inorganic particles, but it is easy to control the particle size and can be dispersed in a solvent. Inorganic particles are preferred. Examples of the material of the inorganic particles include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), zinc oxide (ZnO), barium titanate (BaTiO ₃ ), and the like. Among these, materials having a relatively low relative dielectric constant such as silica, alumina, and zinc oxide are preferable. Further, it may be a porous particle having mesopores or micropores in the structure, such as mesoporous silica.

  Moreover, the viscosity characteristic of the paste can be adjusted by adjusting the ratio of the resin and the filler in the interlayer insulating film 8. Further, the volume ratio of the resin to the interlayer insulating film 8 is preferably 40% or more, and more preferably 50% or more. Accordingly, an interlayer insulating film that can be used even on a flexible substrate can be obtained.

  For the formation of the individual pixel electrodes 9, a screen printing method using a conductive paste is preferable. As the conductive paste, a known paste can be used, and it is preferable to use a low-temperature thermosetting type based on an organic solvent that does not dissolve the insulating film. Any material can be used as the conductive electrode material of the print paste, but it is necessary to select a material that can be screen-printed and does not attack the underlayer.

  By drying and curing the insulating paste and the conductive paste, the interlayer insulating film 8 and the individual pixel electrodes 9 are formed. The drying / curing temperature of the paste is often limited by the substrate material used and the heat resistance temperature of the organic semiconductor used for the active layer.

  In order to make the organic TFT circuit board 10 as described above into an electronic circuit capable of inputting an electric signal, a connection region (connection terminal portion) of a gate / source terminal portion obtained by extending the electrode wiring (4, 5) of the element is provided. It is necessary to electrically connect the FPC board 20 provided with the external driver IC. In the terminal portion of the display, the electrode end portions of the element are divided into block units each including a plurality of elements, and each block is connected to a connection terminal (terminal electrode) of the FPC board. As shown in FIG. 2B, the electrode wiring of each block is provided in the frame portion, has a length suitable for the layout, and the connection pitch is designed in accordance with the terminal pitch of the FPC board 20. Alternatively, the terminal pitch of the FPC board 20 may be manufactured in accordance with the electrode wiring pitch of the gate / source terminal portion.

  It is necessary to secure the mounting strength by forming the insulating protective film 16 on the gate / source terminal portion of the active drive type organic TFT circuit substrate 10 thus obtained and further forming the mounting electrode 17 described later.

[Ensuring strength of connecting terminal (formation of insulating protective film 16)]
The configuration of the insulating protective film 16 used in the present invention will be described below.
The insulating protective film 16 used in the present invention is a mixture (composite dielectric) of a resin binder and an inorganic filler, thereby ensuring the durability of the connection terminal portion even in an electronic circuit using the plastic substrate 7. Can do. Thereafter, the mounting electrode wiring 17 is formed on the insulating protective film 16 provided so as to be in contact with the gate / source terminal portions and the electrode wirings provided in these connection terminal portions, whereby the FPC board 20 can be reliably mounted. A terminal portion is obtained, and an electric signal can be input by connecting to a driver IC or a power supply circuit.

(About the structure of the insulating protective film 16)
The durability of the insulating protective film 16 can be improved by optimizing the resin: filler volume ratio. At the time of mounting the FPC board, a heat of at least 90 degrees and a pressure of several MPa are applied to the connection terminal portion for several seconds. For this reason, it is preferable that the softening temperature of the insulating protective film 16 is 90 degree | times or more.

  The softening temperature of the insulating protective film 16 is determined by the volume ratio of the resin binder and the inorganic filler constituting the insulating protective film. Further, the heat resistance of the insulating protective film 16 changes not only by the volume ratio of the resin binder and the inorganic filler, but also by the particle size ratio of the inorganic filler and the composition thereof, and the overall film depends on the softening point and pressure resistance of the insulating protective film. The strength is determined.

  The volume ratio of the resin binder to the insulating protective film 16 is preferably at least 45% to 67%, more preferably 45% to 65%. By setting such a blending ratio, an insulating protective film having the most mounting process resistance can be obtained. If the resin binder volume ratio of 16 in the insulating protective film is less than 45% by volume, the flexibility of the insulating protective film is impaired, and the difference in thermal expansion coefficient from the plastic substrate becomes large. Cracks and peeling occur. On the other hand, if the inorganic filler is less than 45% by volume, the durability of the connection terminal portion is impaired. Moreover, when it exceeds 67 volume%, an insulating protective film will flow out in the case of a mounting process, and a mounting electrode will be disconnected.

  The insulating protective film 16 used in the present invention is preferably formed by a screen printing method. Insulating paste must be used to form an insulating protective film by screen printing. The insulating paste can be obtained by kneading an organic solvent in addition to the resin binder and the inorganic filler.

  After the paste printing, the paste is preferably cured and dried by heat or ultraviolet irradiation to obtain a desired pattern. The curing / drying temperature is limited by the heat-resistant temperature of the electronic circuit board, but may be appropriately selected as long as it is within an allowable range. In the case of curing with ultraviolet rays, the functional material may be deteriorated by ultraviolet absorption. In this case, it is preferable to protect the functional material by forming a protective film or to prevent the functional material from being deteriorated by absorption of ultraviolet rays using shadow mask light or the like.

  Since the flexible electronic circuit board of the present invention uses the flexible board 7, the drying / curing temperature of the paste is preferably 200 degrees or less, and more preferably 150 degrees or less. However, the present invention is not limited to this, and if the material used for the electronic circuit is excellent in heat resistance, it can be dried and cured at a higher temperature. Further, when it is desired to form the insulating protective film thick, it can be formed to a desired thickness by repeating the screen printing process and the drying process.

  In addition to being able to uniformly dissolve the resin binder to form a solution (vehicle), it is necessary to select a solvent that does not easily dry during the printing operation. As the organic solvent, a solvent selected from alcohols, glycol ethers, esters, aromatics and the like is preferably used. The solvent may be one kind or a mixture of plural kinds. The boiling point of the organic solvent is preferably at least 150 degrees or more. This is because the screen printing method needs to suppress the drying of the paste during the printing process by using a high boiling point solvent. In addition to the components of the paste composition described above, if necessary, by adding dispersants, plasticizers, viscosity modifiers, etc., paste stability and flexibility can be improved, and a stable printing process is implemented. It becomes possible.

  As the resin binder used for the insulating protective film 16 used in the present invention, conventionally known thermoplastic resins, ultraviolet curable resins, thermosetting resins and the like can be used. Examples of the thermoplastic resin include polyvinyl alcohol resin, polyvinyl acetal resin (polyvinyl butyral resin), phenol novolac resin, ethyl cellulose resin, methyl cellulose resin, and thermosetting resins such as acrylic resin, resol resin, epoxy resin, and melamine resin. It is done.

  For these resin binders, it is preferable to select those that can be uniformly dissolved in an organic solvent and have excellent inorganic filler dispersibility, and those that have excellent adhesion to the material on the surface of the substrate to be printed. It is preferable to ensure the heat resistance. One of the indicators of resin heat resistance is a glass transition temperature, and a glass transition temperature of at least 60 ° C. or higher is preferable. If the glass transition temperature of the resin binder is lower than 60 degrees, the insulating protective film may swell even at room temperature, so that it is expected that the durability of the terminal portion cannot be ensured.

  Further, the weight average molecular weight of the resin binder is preferably 2,000 to 30,000, and if it is less than 2,000, sufficient heat resistance of the insulating protective film cannot be ensured, and 30,000. If it exceeds 1, the adhesion of the insulating protective film will become unstable and it will be difficult to peel off or it will be difficult to obtain a thick film. In addition, the insulating paste will become extremely viscous and the printing process will become unstable. There is a risk of problems in the manufacturing process.

  Since it is a paste used for a printing method for forming a thick film like screen printing, it should be taken into account that the film thickness can be increased while the insulating protective film patterning and the thick film can be obtained simultaneously. . In other printing methods, it is difficult to simultaneously realize patterning and a thick film of 1 μm or more. For this reason, it is preferable to avoid the use of a resin binder having a too high glass transition temperature or a resin binder having a large difference in linear expansion coefficient compared to a plastic substrate because it causes a large film stress.

  Of the above resin binders, the use of a phenol resin is preferred. There are two types of phenolic resins, a thermoplastic novolac type and a thermosetting resol type. The glass transition temperature is higher than 60 degrees, and the effect when used as a resin binder for an insulating protective film is particularly good. When a phenol resin is used, since not only the heat resistance of an insulating protective film but also the filler dispersibility is good, a smooth insulating protective film can be easily obtained.

  As the inorganic filler contained in the insulating protective film 16 used in the present invention, it is preferable to use fine particles and ultrafine particles that can be easily controlled in particle size and can be easily dispersed in a solvent. Further, the resin material can be uniformly dissolved in an organic solvent having a boiling point higher than 150 degrees, and it is preferable to use a polymer resin binder disclosed as a conventionally known screen paste, specifically, those listed above. Can be mentioned. The following description will be made on the assumption that an inorganic filler is used as the fine particles and ultrafine particles, and a polymer resin binder is used as the resin material.

  Examples of inorganic fillers include metal oxide particles and metal hydroxide particles that are versatile in fields such as electronic / electrical materials, ceramic materials, and catalysts. The metal oxide particles may be an oxide or hydroxide of one kind of metal or a composite oxide of a plurality of metals. Specifically, silicon dioxide (silica), aluminum oxide (alumina) Magnesium oxide, manganese dioxide, zinc oxide, zirconia, tin oxide, antimony oxide, barium titanate, magnesium titanate, calcium titanate, magnesium hydroxide, aluminum hydroxide, calcium hydroxide and the like can be used. In addition, inorganic porous particles having micropores or mesopores in the structure, such as zeolite and mesoporous silica, may be used. In particular, the object of the present invention can be achieved more effectively by using silica. Since silica particles have a wide average particle diameter range, there is an advantage that the range in which the durability of the insulating protective film can be ensured is widened by selecting a larger amount of paste, and the dielectric constant of the insulating protective film can be reduced.

  As such silica particles, various synthetic silica fine particles such as fumed silica, colloidal silica, precipitated silica, crystalline silica, pulverized silica, and fused silica can be used. Among these, fused silica is particularly suitable because of its excellent electrical insulation and low impurity content.

(Durability improvement by filler difference ratio)
As the shape of the inorganic filler, a spherical shape, a flake shape, a layer shape, a hollow shape, and the like can be used according to the purpose. However, the use of spherical fine particles allows the filling to be tightly controlled. Particularly preferred. This is because spherical particles have the smallest specific surface area, so that filler agglomeration and resin fluidity are unlikely to occur during filling. Such a spherical inorganic filler has a particle size distribution, and the average particle diameter (d50) of the material indicates a diameter at which the cumulative volume frequency is 50% in the particle size distribution.

  When filled with a single particle size filler, especially when the filler is spherical or substantially spherical, when filled with a high density, a diamond-shaped void is formed between the filler and the insulation formed in the connection terminal portion. The durability of the protective film cannot be secured. Other fillers cannot penetrate into this gap, but if the filler is smaller than this gap, it can penetrate further into this gap, easily reducing the filling rate, and improving the durability of the insulating protective film can do. For this reason, in order to contain an inorganic filler in a resin with a high space ratio, it is preferable to use a mixture of two or more types having different average particle diameters, and among these, the inorganic filler A having the largest average particle diameter The width of the particle size distribution is preferably narrow.

In the inorganic filler contained in the insulating protective film 16 in the present invention, the average particle diameter (d50max: P _A ) of the inorganic filler A having the maximum average particle diameter and the average particle of the inorganic filler B having the minimum average particle diameter The difference ratio of the diameter (d50min: P _B ) is preferably as large as possible. When D = (d50max) / (d50min) = P _A / P _B , when D is small, small fillers efficiently enter the gaps between large fillers. Hard to do. For this reason, D is preferably 3 times or more, and more preferably 5 times or more. On the other hand, when D is large, small fillers tend to aggregate and dispersion stability is lowered. For this reason, it is preferable that D is 25 times or less.

  When an inorganic filler having at least two types of average particle diameters is used, the total volume Va of the inorganic filler A having the maximum average particle diameter and the total volume Vb of the inorganic filler B having the minimum average particle diameter are 0. It is preferable to satisfy 05 ≦ Vb / (Va + Vb) <0.5. That is, the amount of the small filler is preferably 5% or more and less than 50% of the total amount of the filler in terms of volume ratio. If it is less than 5%, the effect of increasing the filling amount by entering the void is hardly obtained, and if it is 50% or more, the volume occupied by the small filler is larger than the void formed by the large filler, and the interpenetration occurs. The effect of increasing the filling amount is reduced.

  In addition to these large fillers and small fillers, other fillers having an average particle size may be mixed, and even when there are three or more types, the space ratio is improved by appropriately selecting the particle size and the mixing ratio. The effect is obtained.

The inorganic filler used in the present invention includes at least two kinds of inorganic fillers having different average particle diameters, and the average particle diameter of the inorganic filler having the largest average particle diameter is preferably 1 μm or less. Moreover, it is more preferable that it is 0.3 micrometer or more.
Here, when an insulating protective film is formed on the connection terminal portion using an inorganic filler having the largest average particle diameter and an average particle diameter larger than 1 μm, the filler protrudes from the film surface and the surface unevenness is increased. It becomes a shape that easily deforms with respect to pressure, and it is difficult to obtain a connection terminal portion with good durability. In addition, when the inorganic filler having the maximum average particle diameter is 1 μm or less, the unevenness of the film surface is reduced, so that the mounting pressure is applied evenly and the connection terminal portion with good durability Is obtained.

  On the other hand, when it is desired to obtain an insulating protective film with good heat resistance, if the maximum average particle size is smaller than 0.1 μm, the thermal damage increases due to the large specific surface area of those fillers, and Heat resistance cannot be ensured. On the other hand, when the maximum average particle size is 0.3 μm or more, the filler surface area becomes small and is hardly affected by thermal damage. Further, when the average particle size of the inorganic filler having the maximum average particle size is 0.3 μm or more, the average particle size of the inorganic filler having the maximum average particle size and the average particle size of the inorganic filler having the minimum average particle size Since the difference ratio D can be made sufficiently large, the filling rate is not affected.

  Moreover, in this invention, it is preferable that the average particle diameter of the inorganic filler which has the minimum average particle diameter is 0.01-0.1 micrometer. Furthermore, it is more preferable to use a 0.04-0.06 micrometer thing. In the insulating protective film used in the present invention, it is necessary to take a difference ratio between the maximum average particle diameter and the minimum average particle diameter to perform high-density filling. Therefore, the inorganic filler having the minimum average particle diameter is the maximum It is appropriately selected from the above range depending on the average particle diameter. The filling rate can be increased by increasing the difference ratio D between the average particle diameter of the inorganic filler having the minimum average particle diameter and the average particle diameter of the inorganic filler having the maximum average particle diameter.

Here, the space ratio, which is the ratio of the voids of the spherical particles, was calculated by a two-component particle mixed packed bed space ratio estimation program (Michitaka Suzuki et al.). The space ratio here is used in the opposite meaning of the filling rate. FIG. 3 shows a change in the space ratio when particles having a particle diameter of 0.3 μm and a space ratio of 50% are mixed with particles having a particle diameter of 0.1 μm and a space ratio of 50%.
It can be seen that by mixing two types of spherical particles having different average particle diameters, the space ratio is reduced to less than 50% of both. When the mixing ratio of the small particles is 37% by weight, the space ratio is minimum at 44%.

Subsequently, a change in the small particle mixing ratio of the space ratio when mixing particles having a particle diameter of 0.3 μm and a space ratio of 50% and particles having a particle diameter of 0.04 μm and a space ratio of 50% is also illustrated. When particles having a particle diameter of 0.04 μm are mixed, when the small particle mixing ratio is 27% by weight, the space ratio becomes 33% and becomes the minimum.
From the above simulation results, comparing the case where a particle size of 0.1 μm is mixed with a particle size of 1 μm and the case where a particle size of 0.04 μm is mixed, a case where a particle size of 0.04 μm is mixed is large. It can be seen that the decrease in the spatial ratio is larger. In addition, it can be confirmed by calculation that the larger the average particle size ratio, the smaller the mixing ratio of small particles that minimizes the space ratio.

  Measurement of the average particle size contained in the paste composition and the dielectric composition in the present invention is an XMA measurement on an ultra-thin slice obtained by forming an insulating protective film and cutting a film cross section in the film thickness direction of the thin film. It can be measured by observation with a transmission electron microscope (TEM). Since the transmittance with respect to the electron beam is different between the inorganic filler and the resin, the inorganic filler and the resin can be identified by the difference in contrast in the TEM observation image. When a plurality of types of inorganic fillers are used, each inorganic filler can be identified by elemental analysis based on XMA measurement and crystal structure analysis by electron diffraction image observation. The distribution of the area of the filler and the resin thus obtained is obtained by image analysis, and the particle diameter can be calculated from the area by approximating the cross section of the inorganic filler to be circular.

  The particle size may be evaluated for TEM images with a magnification of 5000 times and 40000 times. The calculated particle size distribution is represented by a histogram in increments of 0.1 μm in a TEM image with a magnification of 5000 times and a histogram in 0.01 μm increments in a TEM image with a magnification of 40000 times. Is the average particle size. In the present invention, “having at least two kinds of average particle diameters” means that there are two or more maximum values, and two or more maximum values in the particle size distribution of the inorganic filler contained in the composition. It exists. As an evaluation method of the particle size distribution, a scanning electron microscope (SEM) may be used instead of TEM in the above method.

  For the formation of the insulating protective film 16, it is preferable to use a screen printing method. Hereinafter, an outline of the off-contact screen printing method will be described, and then selection of a screen mesh will be described.

(Off-contact screen printing method)
In the off-contact screen printing method, first, a screen plate 103 made of stainless mesh is prepared, and a clearance (gap) is provided between the printing substrate 102 placed on the stage 100 and the screen plate 103 ( FIG. 4a). The screen plate 103 includes a screen emulsion 103B and an opening 103A that is a gap therebetween, and is held by a screen plate frame 105. Next, as shown in FIG. 4 b, when the paste 104 is placed on the screen plate 103 and printed with the squeegee 101, the print paste 104 is in close contact with the printed substrate 102 near the squeegee 101, and receives external force by sliding the squeegee 101. Since the paste 104 flows, it is filled into the screen plate 103 in front of the squeegee 101 (a filling vector works in the direction of the arrow in FIG. 4B).

  At this time, the screen plate 103 has a clearance (gap amount between the substrate to be printed and the screen plate) of 0 mm immediately below the squeegee, and a large tension is generated in the screen plate frame 105 due to mesh elasticity. Therefore, behind the squeegee with respect to the printing direction, the screen plate 101 starts to separate from the surface of the substrate to be printed 102 due to the strong tension of the mesh (plate separation).

  Therefore, a large shear stress acts on the paste filled in the mesh, and the viscosity of the paste having thixotropy is further rapidly reduced. As a result, the paste passes through the mesh, and the pattern 106 transferred and transferred to the surface of the substrate 102 to be printed is formed. More specifically, since the printing paste 104 has thixotropy, the thick film having the pattern 106 can be formed by recovering the viscosity over time and maintaining the pattern shape.

  The screen printing method can form a desired printing pattern with high dimensional accuracy, and is also a useful printing method for a substrate surface having surface irregularities. In addition, it is important to understand the screen plate specifications, printing paste, and points to note when forming patterns.

  In this way, after forming the insulating protective film 16 on the gate terminal portion, the mounting electrode 17 is formed to complete the thickening of the connection terminal portion. The mounting electrode 17 can be formed in the same manner as the pixel electrode 9 and is preferably formed by screen printing. Since the insulating protective film 16 is formed on the connection terminal portion and the surface has an uneven shape, the characteristics of screen printing can be utilized to the maximum. The mounting electrode 9 may be formed by screen printing using an anisotropic conductive paste [ACP: Anisotropic Conductive Paste].

  As the organic TFT element, one produced by the following method was used. Subsequently, an interlayer insulating film 8 and a pixel electrode 9 were formed on the organic TFT element 10 to obtain an organic TFT circuit substrate 10. Further, an insulating protective film 16 and a mounting electrode 17 were formed on the connection terminal portion of the organic TFT circuit substrate 10 to obtain an active drive circuit substrate with improved durability of the connection terminal portion. Finally, an electroconductive display element and an active drive circuit board were bonded together, and an image switching test was performed.

(1) Organic TFT circuit board 10
A commercially available nano silver ink was used for the polyethersulfone substrate 7 and an inkjet (IJ) apparatus was used, and after IJ printing in a desired pattern, heat treatment was performed at 150 ° C. to form a first electrode.

  Next, a heat-polymerizable polyimide is applied as a first insulating film by spin coating, heat-treated at 180 ° C., and then irradiated with ultraviolet rays through a photomask to a desired portion (second electrode forming portion described later). And surface modification was performed.

  Next, the 2nd electrode was formed by the IJ printing method using nano silver ink similarly to 1st electrode formation. The pattern of the exposed part cannot be recognized by CCD observation. Therefore, the substrate was aligned with the first pattern, and printing was performed by the IJ printing method based on the print data.

  An organic semiconductor was formed in the active layer (organic semiconductor layer 6). The organic semiconductor was formed by dissolving an organic semiconductor material having a triarylamine skeleton represented by the following structural formula 1 in xylene and forming an ink. The ink concentration was 1 wt%, the viscosity was about 5 mPa seconds, and the surface tension was about 30 mN / m. Then, the organic transistor circuit board was obtained by forming a film | membrane in the site | part desired by the IJ printing method. This compound is a non-oriented polymer material disclosed in Japanese Patent Application Laid-Open No. 2008-041889, but it is disclosed that there is little variation in transistor characteristics regardless of the film formation shape and film formation method.

  Here, in Structural Formula 1, Ar is an aryl group, and R is an alkyl group.

(Interlayer insulating film 8 and individual pixel electrode 9)
The interlayer insulating film 8 was formed of a paste of an insulating material containing a butyral resin and a silica filler by screen printing, and dried in a convection oven at 120 ° C. for 30 minutes to form an interlayer insulating film. Here, the drain electrode was formed in a shape having an opening (through hole) of the interlayer insulating film. The film thickness was 10 μm.

  As the individual pixel electrode 9, a conductive paste was formed using a screen printing method and cured at 120 ° C. for 30 minutes to obtain an individual pixel electrode. In the butt portion of the drain electrode, the individual pixel electrode material is formed on the opening of the interlayer insulating film 8. Since the drain electrode 3 and the individual pixel electrode 9 are electrically connected through the through hole of the interlayer insulating film 8, the drain output is output to the pixel electrode. The film thickness was 10 μm.

  In the present example, the conductive paste used was a low temperature sintered type (FA451) manufactured by Fujikura Kasei Co., Ltd., and a viscoelasticity adjusted by appropriately adding a diluent.

  Hereinafter, specific examples of forming the insulating protective film 16 on the connection terminal portion will be listed. First, the volume% of the resin binder contained in the insulating protective film 16 was changed according to Examples 1 and 2 and Comparative Example 1, and the results of confirming the mounting durability were summarized in Table 1. Subsequently, according to Examples 3 and 4, the average particle diameter of the filler contained in the insulating protective film 16 is changed, the FPC substrate and the electroconductive display panel are bonded together to produce an image display device, and the display switching test is performed. The results obtained are summarized in Table 2.

[Example 1]
(2) Formation of Insulation Protection Film 16 on the Connection Terminal Part The insulation protection film 16 is formed on the gate and source terminal parts of the organic TFT circuit substrate 10.
In this embodiment, only the gate terminal portion 14 is shown in the figure as an example. 2B is a plan view and a cross-sectional view of the gate terminal portion 14 at an end portion where the gate selection line 4 is extended. FIG. 2C shows an insulating protective film 16 formed on the gate terminal portion 14, and FIG. 17 is formed.
Further, in this embodiment, a block unit in which the gate selection lines 4 of the circuit board are arranged at equal intervals is arranged on the frame of the circuit board. Hereinafter, embodiments of the insulating protective film 16 formed on the gate terminal portion 14 will be described in detail. The same applies to the source terminal portion 15 at the end where the source signal line 5 is extended.

(Preparation of insulating paste)
The insulating paste for screen printing on the gate terminal electrode is silica fine particles (electrochemical) with an average particle size of 0.3 μm in a vehicle in which phenol resin is dissolved in ethylene glycol (Tokyo Ohka: GR) at 40% by weight. A product obtained by dispersing 20% by weight of an industrial product (SFP20M) and 10% by weight of silica ultrafine particles (manufactured by Denki Kagaku Kogyo Co., Ltd .: uFP30) having an average particle size of 0.04 μm was used. At this time, 30% by weight of filler was dispersed in 70% by weight of the vehicle. When this insulating paste is used, the resin volume ratio of the insulating protective film 16 is 65% by volume.

  The screen plate 103 was prepared by forming a photosensitive emulsion having a thickness of 15 μm on a stainless steel mesh having a plain weave No. 400 and exposing and patterning the emulsion so as to form an emulsion opening of the screen plate. The screen plate 103 was arranged at a constant interval from the substrate, and screen printing was performed using the insulating paste 1 to form the insulating protective film 16 on the gate terminal electrode.

  The printing conditions were a clearance of 1.8 mm and a squeegee speed of 30 mm / s. The squeegee 101 was a urethane rubber squeegee, and the attack angle was 70 degrees (the angle between the substrate surface and the squeegee, which is the squeegee scanning direction side). The printed paste was heat-treated at 120 ° C. for 1 hour using a convection oven to form an insulating protective film (No. 1) on the gate terminal electrode portion.

Subsequently, it is necessary to form the mounting electrode 17 on the gate terminal electrode.
As shown in FIG. 2d, the mounting electrode 17 is formed on the insulating protective film 16 and the electrode surface of the gate connection portion.
As the conductive thick film paste, the above-mentioned Ag paste for screen printing was used, and the viscosity was adjusted to about 200 [Pa · s].

  For the screen plate 103, a plain weave No. 500 stainless mesh was used, and the mesh was plated with Ni having a thickness of 3 μm. A photosensitive emulsion having a thickness of 10 μm was formed on the screen mesh and exposed and patterned so that the design value of the mounting electrode 17 would be the emulsion opening of the screen plate. Although details are not shown in the figure, the one laid out so that the opening of the mounting electrode 17 is positioned on the gate electrode terminal is used.

  The screen plate 103 was arranged at a constant interval from the substrate, and screen printed on the electrode surfaces of the insulating protective film 16 and the gate terminal portion 14 using a conductive paste. The printing conditions were a clearance of 1.8 mm and a squeegee speed of 60 mm / s. The attack angle was 50 degrees.

  Subsequently, drying was performed at 150 ° C. for 1 hour in a convection oven to obtain a thick gate connection. When the electrical resistivity (volume electrical resistivity) of the gate terminal portion after the heat treatment was measured, it was 1E-5 Ω · m or less, and it was confirmed that it functions as a wiring material.

(Mounting of FPC board 20)
The gate connection terminal portion obtained as described above was mounted by using the FPC board 20 having a driver IC. The connection terminal (terminal electrode) 18 of the FPC board 20 is Cu, and the terminal side of the FPC board 20 used is a laminate of ACF 19 in which conductive particles are dispersed (FIG. 2e).
First, the terminal of the FPC board 20 and the gate mounting electrode 17 are aligned and contacted via the ACF 19. In this state, the gate terminal was heated and preheated at 70 degrees. Thereafter, the temperature was increased to 140 ° C., and a pressure of 1.5 MPa was applied to perform thermocompression bonding so that the conductive particles were in contact between the connection terminal and the gate terminal of the FPC board. By setting the heating temperature to 140 ° C., the thermosetting resin contained in the ACF is cured, and simultaneously pressed to contact the conductive particles between the connection terminal of the FPC board and the mounting electrode of the gate terminal portion (see FIG. 2f). As a result, electrical continuity between the connection terminal 18 of the FPC board 20 and the gate mounting electrode 17 can be ensured.

  The surface of the gate terminal portion of the active drive circuit board fabricated as described above was observed using an optical microscope. As a result, no defect was found in the electrodes formed on the connection terminal portions, and no alteration was observed in the insulating protective film. When the electrical resistivity (volume electrical resistivity) of the gate terminal portion after the heat treatment was measured, it was 1E-5 Ω · m or less, and it was confirmed that it functions as a wiring material.

[Example 2]
Insulating pastes having different vehicle weight% and filler weight% were prepared. Specifically, the same vehicle as in Example 1 was blended in the range of 65% to 45% by weight with respect to the insulating paste. The blending ratio of the large and small fillers was unified with the weight ratio of Example 1. In this way, the resin volume ratio in the insulating protective film was in the range of 67 volume% to 40 volume%.

  Using these insulating pastes, an insulating protective film (No. 2 to No. 6) was obtained by performing screen printing on the gate terminal portion in the same manner as in Example 1. Subsequently, an FPC board was mounted under the same conditions as in Example 1 to obtain an active drive circuit board.

  The surface of the gate terminal portion of the active drive circuit board fabricated as described above was observed using an optical microscope. As a result, minute cracks were observed in a part of the insulating protective film (No. 6). The other insulating protective films were not altered.

[Comparative Example 1]
Insulating pastes having different vehicle weight% and filler weight% were prepared. Specifically, two types of vehicles similar to those in Example 1 were blended in the range of 35% by weight and 65% by weight with respect to the insulating paste. About the filler, it unified with the mixture ratio of Example 1. FIG. In this way, the resin volume ratio in the insulating protective film was set to 35 volume% and 70 volume%.

  An insulating paste having a resin volume ratio of 35% by volume and 70% by volume of the insulating paste of Example 1 was prepared, and the insulating protective film No. 1 was printed under the same printing conditions as in Example 1. 7, 8 were obtained. Subsequently, an FPC board was mounted under the same conditions as in Example 1 to obtain an active drive circuit board.

  The surface of the gate terminal portion of the active drive circuit board fabricated as described above was observed using an optical microscope. As a result, the insulating protective film (No. 7) was dissolved, and the mounting electrode of the gate terminal portion was disconnected. Further, the insulating protective film (No. 8) was peeled off from the gate terminal portion. The insulating protective film (No. 7) has a large resin binder volume%, and it is considered that the insulating protective film flowed out because the FPC board was pressure-bonded in a state in which the insulating protective film easily flows by the heat treatment of the mounting process. In this process, it is considered that pressure is applied to the mounting electrode between the FPC board and the gate terminal portion by the extrusion of the insulating protective film, and the mounting electrode is thereby disconnected. Because the resin binder volume% contained in the insulating protective film (No. 8) was small, the linear expansion coefficient of the insulating protective film decreased, the difference in linear expansion coefficient from the plastic substrate increased, and the film stress increased. It is thought that cracks occurred and peeled off.

  From the above results, it was found that the resin volume% contained in the insulating protective film should be 45 volume% to 65 volume% using a phenol resin as the resin binder.

[Example 3]
In the insulating paste of Example 1, the average particle diameter of the silica filler fine particles was changed.
30% by weight of silica fine particles having an average particle size of 0.08 μm and ultrafine silica particles having an average particle size of 0.04 μm (electrochemistry) with respect to a vehicle in which phenol resin is dissolved in ethylene glycol (Tokyo Ohka: GR) at 40% by weight Industrial product: uFP30) 5% by weight dispersed was used. At this time, 35% by weight of filler was dispersed in 65% by weight of vehicle.

  Similarly, four types of insulating pastes were prepared using silica fine particles having average particle sizes of 0.5 μm, 1.0 μm, and 1.2 μm. At this time, 35% by weight of filler was dispersed in 65% by weight of vehicle. When the insulating paste produced as described above is used, the resin volume ratio of the insulating protective film is 60% by volume. In the insulating protective films having the same film thickness, the durability of the connection terminal portion when the particle diameter of the silica fine particles is changed is examined.

  An insulating protective film (No. 9-12) was formed on the gate terminal portion using the above four types of insulating paste. The printing conditions and drying conditions are the same as in Example 1. Subsequently, an electrophoretic display panel is manufactured by pasting an active drive circuit board having an insulating protective film (No. 9-12) formed on the gate terminal portion with a display panel using an electrophoretic element. In order to investigate the electrical continuity of the gate terminal portion, an electroconductive display panel was produced and the display of the image was switched.

(3) Electrophoretic Display Panel: Production of Image Display Device The electrophoretic display panel includes an opposing substrate 12 provided so as to face an active drive circuit substrate, and an electrophoretic element layer 13 provided between these substrates. (FIGS. 2a and 2b). Further, it further has an upper substrate 11.

  The electrophoretic element layer 13 includes a plurality of microcapsules as disclosed in Patent Document 1. The microcapsules are formed of a resin film, and a plurality of microcapsules are arranged so as to cover the entire display area. In addition, since the microcapsules are actually in close contact with each other, the display region is covered with the microcapsules without any gaps.

  The microcapsule encloses an electrophoretic dispersion liquid having a dispersion medium, electrophoretic particles, and the like. Examples of the electrophoretic particles include titanium dioxide, zinc oxide, magnesium oxide, bengara, aluminum oxide, black low-order titanium oxide, chromium oxide, boehmite, FeOOH, silicon dioxide, magnesium hydroxide, nickel hydroxide, zirconium oxide, Copper oxide or the like is used.

  The dispersion medium uses non-aqueous organic solvents such as hydrocarbons, halogenated hydrocarbons, ethers, etc. Spirit Black, Oil Yellow, Oil Blue, Oil Green, Bali First Blue, Macrolex Blue, Oil Brown, Sudan It is dyed with a dye such as black or first orange and has a different hue from the electrophoretic particles.

  In this example, microcapsules encapsulating titanium oxide fine particles and isopar colored with oil blue are mixed in a PVA aqueous solution and coated on a polycarbonate substrate on which a transparent electrode made of ITO is formed. The following electrophoretic display panel was formed.

  The display panel and the active drive circuit board are bonded together and the power supply circuit is connected to the FPC board 20 to complete the electrophoretic display panel. The image display can be switched by inputting an electric control signal to the connection terminal of each block in which the gate selection line and the source signal line of the display panel are bundled.

(Electrophoretic display panel)
An electroconductive display panel was manufactured using an active drive type circuit board having an insulating protective film (No. 9-12) formed on the gate terminal portion. A UV curable sealant is applied to the outer periphery of the matrix area, which is a driving unit, with a dispenser, and after the electrophoretic display panel is bonded, the counter electrode of the display panel is connected to the driving device, and the gate selection line of the circuit board Then, an electric signal was input to the source signal line and an operation test was performed.

  The display panel using the insulating protective film (No. 10, 11) was able to obtain uniform display contrast and resolution. In the display panel using the insulating protective film (No. 12), several line-like defects were observed. Further, the display panel using the insulating protective film (No. 9) could not obtain contrast due to display switching.

  In the insulating protective film (No. 9), the silica filler fine particles used in the insulating protective film had a large specific surface area, so that the heat damage of the mounting process was large and the heat resistance of the connection terminal portion could not be ensured. In addition, in the insulating protective film (No. 12), it is considered that the filler easily protrudes from the film surface and the surface unevenness is likely to increase, so that the insulating protective film (No. 12) is easily deformed with respect to the mounting pressure. For this reason, it is thought that the connection terminal part with favorable durability was not obtained by the pressure of the mounting process.

[Example 4]
Of the insulating paste of Example 1, the particle size of the silica filler ultrafine particles was changed.
33% by weight of silica fine particles with an average particle size of 0.3 μm and 2% by weight of ultrafine silica particles with an average particle size of 0.007 μm with respect to a vehicle in which phenol resin is dissolved in ethylene glycol (Tokyo Ohka: GR) at 40% by weight What was dispersed was used. At this time, 35% by weight of filler was dispersed in 65% by weight of vehicle.

  Similarly, five types of insulating pastes were prepared using ultrafine silica particles having particle sizes of 0.01 μm, 0.06 μm, 0.1 μm, and 0.12 μm. At this time, 35% by weight of filler was dispersed in 65% by weight of vehicle. When the insulating paste produced as described above is used, the resin volume ratio of the insulating protective film is 60% by volume. In the insulating protective films having the same film thickness, the durability of the connection terminal portion when the particle diameter of the ultrafine silica particles is changed is examined.

  An insulating protective film (No. 13-17) was formed on the gate terminal portion with these insulating pastes. The printing conditions and drying conditions are the same as in Example 1. Subsequently, an electrophoretic display panel is manufactured by pasting an active drive circuit board having an insulating protective film (No. 13-17) formed on the gate terminal portion to a display panel using an electrophoretic element. In order to investigate the electrical continuity of the gate terminal portion, an electroconductive display panel was produced and the display of the image was switched.

  The display panel using the insulating protective film (No. 15, 16) was able to obtain uniform display contrast and resolution. In the display panel using the insulating protective film (Nos. 13 and 14), no contrast was obtained by display switching. On the other hand, in the display panel using the insulating protective film (No. 17), several line-like defects were observed. In the insulating protective films (Nos. 13 and 14), although the packing density of the silica filler used for the insulating protective film was sufficient, the thermal damage of the mounting process was large due to the large specific surface area. It is thought that the heat resistance of was not able to be secured. In addition, in the insulating protective film (No. 17), it is considered that the filling density is insufficient, the surface unevenness is increased, and the insulating protective film (No. 17) is easily deformed with respect to the mounting pressure. For this reason, it is thought that the connection terminal part with favorable durability was not obtained by the pressure of the mounting process.

The results of Examples 1 and 2 and Comparative Example 1 are summarized in Table 1, and the results of Examples 1 to 4 and Comparative Example 1 are summarized in Table 2 below. In the determination results of the display test in Tables 1 and 2, ◯ indicates that the display contrast is good, and X indicates that a good display contrast cannot be obtained.
Insulating protective film No. obtained in Examples 1 to 4 and Comparative Example 1 above. 1-17. Nos. 6 to 8 correspond to comparative examples. 9, 12 to 14 and 17 correspond to reference examples.

  From the above results, in an electronic circuit such as an organic thin film transistor element in which an organic semiconductor is laminated on a flexible substrate, the strength of the mounting connection terminal portion can be improved to ensure electrical continuity with the FPC substrate.

DESCRIPTION OF SYMBOLS 1 Gate electrode 2 Source electrode 3 Drain electrode 4 Gate selection line 5 Source signal line 6 Organic-semiconductor layer (active layer)
7 (flexible) substrate 8 interlayer insulating film 9 pixel electrode 10 organic TFT substrate 11 upper substrate 12 counter electrode 13 electrophoretic display element 14 gate connection terminal block (gate terminal portion)
15 Source connection terminal block (source terminal block)
16 Insulating protective film 17 Mounting electrode 18 Terminal electrode (connection terminal)
19 ACF
20 FPC board 100 Stage 101 Printing squeegee 102 Printed board 103 Screen mesh (screen version)
104 Printing paste 105 Screen plate frame 106 Transferred pattern

Japanese Patent Laid-Open No. 10-274779 JP-A-7-209663 JP 2007-103584 A JP 2007-123665 A JP 2006-41374 A

Claims (5)

A flexible electronic circuit board in which a flexible substrate and an electronic circuit including an organic semiconductor layer are stacked on the substrate,
It has a connection terminal part connected to the terminal electrode provided in the flexible printed circuit board,
The connection terminal portion includes an electrode wiring, and an insulating protective film is formed so as to be in contact with the electrode wiring.
The insulating protective film includes at least a resin binder and an inorganic filler,
The volume ratio of the resin binder contained in the insulating protective film is 45% or more and 67% or less ,
The inorganic filler includes at least an inorganic filler A and an inorganic filler B,
The inorganic filler A is the average particle size _{P A} is the largest of the inorganic filler, and an average particle size _{P A} is 0.3～1Myuemu,
The inorganic filler B has an average particle size P _B which is the smallest among the inorganic fillers,
The ratio _P A / _{P B} and the _{P B} and the _{P A,} the flexible electronic circuit board, characterized in that 3 to 25. The flexible electronic circuit board according to claim 1, wherein the resin binder is a phenol resin. The inorganic filler is a flexible electronic circuit board according to claim 1 or 2, characterized in that the silica. An image display device comprising: the flexible printed circuit board according to claim 1; and the flexible printed circuit board and a power supply circuit connected to the flexible electronic circuit board according to claim 1 ; and a display panel attached thereto. . It is a manufacturing method of the flexible electronic circuit board according to any one of claims 1 to 3 ,
The method for manufacturing a flexible electronic circuit board, wherein the insulating protective film is formed by a screen printing method.