JP2007171596A - Substrate for display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for a display device which is lightweight and thin and has good display quality. <P>SOLUTION: Disclosed is the substrate for the display device, such as a liquid crystal display element in which semiconductor thin film element and thin film for wiring are directly formed on a surgace of the polyimide film insulating base (TN liquid crystal, STN liquid crystal, ferroelectric liquid crystal, guest-host type liquid crystal, cholesteric liquid crystal, etc.), an EL display element, an electrophoretic display element, and an electrochromic display element which uses a polyimide film of ≤10% in curl degree at 300°C consisting principally of polyimide obtained by subjecting aromatic diamines and aromatic tetracarboxylic acids to reaction for an insulating base material. Preferably, the substrate for the display device uses, as the insulating base material, a polyimide film of -5 to 16 ppm/°C in coefficient of linear expansion consisting principally of polyimide benzooxazole obtained by subjecting aromatic diamines having benzooxazole structures and aromatic tetracarboxylic acides to reaction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a substrate for a display device having flexibility, and more specifically, for a display device in a display device including a substrate for a display device in which a semiconductor thin film element and a thin film for wiring are directly formed on a specific polyimide film, and the display element. The present invention relates to a substrate for a display device including a holding circuit including a semiconductor thin film element, a thin film for wiring, and the like, which is a substrate and is formed using a polyimide film having specific heat-resistant physical properties as a support.
The present invention relates to a substrate for a display device as a member for the display device.
More specifically, as a display device, a flat-screen television, a wall-mounted television, a handheld television, a stationary personal computer display unit, a mobile personal computer, a portable display device, an acoustic device display unit, portable music playback Display unit of machine, display unit of in-vehicle amusement device, display of portable communication device, display device in cockpit such as mobile phone, mobile vehicle such as automobile, ship, aircraft, display unit of car navigation system, public transportation Guidance display, advertisement, publicity media, wristwatch, head mounted display, video camera, digital still camera, etc., electronic dictionary, PDA, electronic notebook, GPS, portable game machine, portable karaoke machine, toy display unit, Digital and silver halide camera display and status display / control The display unit of the Lumpur part, computer displays and a display unit of the state display and control unit of the TV monitor, watch, those that are using the electronic display device with a watch other than a wristwatch. In addition, remote control displays for various home appliances, refrigerators, washing machines, microwave ovens, electric kettles, jar pots, dishwashers, electric refrigerators, cooking heaters, ventilation fans, electric water heaters, natural refrigerant heat pump water heaters, homes Electric well pumps, air purifiers, electric washing machines, washing machines (fully automatic, two-tank type), washing and drying machines, vacuum cleaners, warm water toilet seats, electric razors, household garbage processing machines, coolers, etc. Display units for home appliances, display units for electrical lighting equipment, video recorders, DVD recorders, HD recorders, stereos, home theater systems, display units for AV equipment such as radios, copiers, printers, faxes, telephones and other office equipment Display unit, printer, CD drive, FD drive, MO drive, DVD drive, hard disk, memory card Computer peripherals such as reader / writers, modems, routers, hubs, etc., display units of computer bodies, door phones, fire alarm systems, gas detection, security system and other housings, building equipment display units, health meters, blood pressure measuring instruments, electricity Display units for health promotion equipment such as massage appliances, civil engineering machinery, mining machinery, chemical machinery and storage tanks, pulp and paper machinery, plastic processing machinery, pumps, compressors and blowers, hydraulic machinery and pneumatic equipment, power transmission devices , Agricultural machinery and equipment, wood processing machinery, metal machine tools, metal processing machinery and casting equipment, food processing machinery, packaging machinery and packing machinery, sewing machines and textile machinery, refrigerators and refrigerator application products, vending machines, automatic Ticket gate / automatic entrance machine, rotating electrical machine, stationary electrical machine, opening / closing controller , Semiconductor equipment, home appliances, production equipment in various industries such as automobiles, display parts of machine tools, electronic exchanges, digital transmission devices, display parts in communication equipment, automatic teller machines (including payment machines), etc. And display units of electrical measuring instruments and electronic application devices, measuring instruments, and the like.

Thin display devices include liquid crystal display devices, electroluminescence display devices, plasma displays, electrophoretic display devices, field emission display devices, electrochromic display devices, rotating sphere display devices, rotating cylindrical display devices, and electronic jet fluids. A display device using movement of dry powder is known.
Such a display device includes, as its constituent members, a display panel that embodies the display principle itself, and a circuit panel that includes a drive circuit for generating and transmitting a drive signal.
Generation and transmission of such drive signals are performed by an integrated circuit called a driver IC, and are connected to the display panel via an extremely thin circuit board called a tape substrate.
With the recent increase in definition of display panels, the number of drive signal lines led from driver ICs has increased to a very large number, and the pitch of wiring has become very small. For this reason, expansion and contraction of the wiring pitch due to changes in temperature and humidity, warping of the tape substrate, twisting and deformation of the wiring due to deformation have an increasing effect on the product yield.

As these conventional display devices, for example, as a light-receiving display device that is easy to adjust to eyes like printed matter and does not cause eye fatigue due to external light, a spherical, ellipsoidal or columnar display element, and a display element A display device (see Patent Document 1) in which one or more of these are enclosed in a transparent hollow cylinder, and a plurality of microcapsules whose optical reflection characteristics are changed by application of an electric field are reliably installed at a desired position. As a result, a display device capable of high-definition and high-quality multi-color and color display (see Patent Document 2), an array side substrate on which pixel electrodes and an electrochromic layer are formed, a counter electrode and an electrochromic layer are formed. In an electrochromic display device comprising a color filter side substrate and an electrolytic layer injected between the array side substrate and the color filter side substrate, A high-definition electrochromic display device that prevents a short circuit between pixel electrodes or a short circuit between electrochromic layers between adjacent pixels by providing a partition wall around the chromochromic layer (see Patent Document 3) Other liquid crystal display elements (TN liquid crystal, STN liquid crystal, ferroelectric liquid crystal, guest-host liquid crystal, cholesteric liquid crystal, etc.), EL display elements, electrophoretic display elements, electrochromic display elements, oxidation A reduction type display element, a rotating sphere type or rotating cylindrical type display element, an electronic powder fluid type display element (see Patent Document 4), and the like are also known.
JP 2002-202536 A JP 2002-365668 A JP 2005-049770 A JP 2003-248245 A

Many of these various display elements as described above are known, and many display apparatuses including other elements to be included as a display apparatus such as a semiconductor that bears a driving unit that operates integrally with these display elements are also proposed. Has been.
For example, in an active matrix semiconductor display device in which a pixel TFT and a drive circuit TFT are integrally formed on the same substrate, a gap holding material (polyimide is used as the gap holding material) disposed between the pixel region and the drive circuit region. Resin is an example), the cell gap can be controlled, and a uniform cell thickness can be obtained over the entire semiconductor display device, and since a conventional grain spacer is not used, when the active matrix substrate and the counter substrate are bonded together, An active matrix semiconductor display device (see Patent Document 5) that can prevent damage to the drive circuit TFT in which no stress is generated in the drive circuit TFT, or a liquid crystal sealed between a pair of substrates, The matrix is crossed vertically and horizontally through an interlayer insulating film (polyimide resin, etc.) on the substrate. A gate wiring and a source wiring arranged in a square shape are formed, and a thin film transistor is formed by being electrically connected to the gate wiring and the source wiring, and the thin film transistor is formed in a region partitioned by the gate wiring and the source wiring. A liquid crystal display in which a pixel electrode is formed by electrical connection, and a dielectric constant of a gate insulating film interposed between a gate electrode forming the thin film transistor and a semiconductor active layer is larger than a dielectric constant of the interlayer insulating film An organic insulating tape having a device hole for mounting a semiconductor integrated circuit element, in which reliability is improved by preventing lead disconnection due to a thickness difference of an apparatus (see Patent Document 6) and a base film, and the organic insulating tape The inner leads for bonding semiconductor integrated circuit elements and the output and input side outer leads The aspect ratio is about 4 or more, which is arranged and connected to the metal foil layer on which the wiring pattern of the wiring is formed and the inner lead so that the longitudinal direction is parallel to the width direction of the organic insulating tape. Many types of polyimide resins and films (see Patent Document 4) have been proposed for tape carrier packages for liquid crystal drivers having certain semiconductor integrated circuit elements (see Patent Document 7) and insulating substrates for various elements of these display devices. .
Japanese Patent Laid-Open No. 10-319440 Japanese Patent Laid-Open No. 10-048610 JP 2002-277894 A

  The present invention can withstand repeated heating and cooling applied to the insulating equipment (substrate) during the manufacturing process of the substrate for a display device, and can maintain sufficient reliability even when thermal stress is applied in a circuit forming process. It is an object of the present invention to provide a substrate for a display device, a lightweight and thin substrate for a display device, and a display device including the same as a component.

As a result of intensive studies, the present inventors have found that the object is achieved by using a polyimide film, which is a heat-resistant polymer film having specific physical properties, as an insulating substrate of a substrate for a display device.
That is, this invention consists of the following structures.
1. A polyimide film having a curl degree of 10% or less at 300 ° C., which is mainly composed of polyimide obtained by reacting aromatic diamines and aromatic tetracarboxylic acids, is used as an insulating base, and the surface of the polyimide film insulating base And a substrate for a display device, wherein a semiconductor thin film element and a wiring thin film are directly formed.
2. The display element is a liquid crystal display element, an EL display element, an electrophoretic display element, an electrochromic display element, a redox type display element, a rotating sphere type or rotating cylindrical type display element, and a display type by moving a dry powder. 2. The substrate for a display device according to 1 above, wherein the substrate is one or more display elements selected from any one of the display elements.
3. 3. The substrate for a display device according to 2 above, wherein the liquid crystal display element is one or more liquid crystal display elements selected from TN liquid crystal, STN liquid crystal, ferroelectric liquid crystal, guest-host liquid crystal, and cholesteric liquid crystal.
4). The insulating base material is a polyimide film having a linear expansion coefficient of −5 to 16 ppm / ° C. mainly composed of polyimide benzoxazole obtained by reacting an aromatic diamine having a benzoxazole structure with an aromatic tetracarboxylic acid. 4. The substrate for a display device according to any one of 1 to 3.
5. A plane orientation coefficient mainly composed of polyimide benzoxazole obtained by reacting an aromatic diamine having an benzoxazole structure with an aromatic tetracarboxylic acid as an insulating substrate is 0.75 or more, and a tensile modulus is The substrate for a display device according to any one of the above 1 to 4, which is a polyimide film having a tensile strength at break of 300 MPa or more and having 5 GPa or more.

  The polyimide film, which is a heat-resistant polymer film having specific physical properties used in the present invention, is excellent in maintaining flatness in the heat history by heating and cooling, has a low coefficient of linear expansion, and is close to a semiconductor material. Stress can be reduced. In addition, since a high tensile elastic modulus and a high tensile breaking strength can be realized, the influence on mechanical stress during semiconductor formation is small. In other words, when the material has a low tensile elastic modulus, the substrate is kept deformed by the stress applied to fix the substrate film during the formation of the semiconductor film. Stress is applied to the formed semiconductor layer and light emitting layer, and good characteristics cannot be exhibited. In addition, since the polyimide film of the present invention has heat resistance that can sufficiently withstand the high temperatures required particularly when forming a thin film semiconductor layer, a substrate for a display device having a high-quality semiconductor thin film element and a thin film for wiring is manufactured. I can do it.

  In the substrate for a display device of the present invention, a driving circuit is a switching thin film transistor, and a TFT or MIM (metal insulator metal structure diode) including a source electrode and a gate electrode for actively driving a display panel (element). However, it is formed in an amorphous silicon layer or a low-temperature polysilicon layer on an insulating substrate, and is covered with a planarizing film. Here, although silicon is used for explanation, it is not necessarily limited to silicon, and organic transistors may be used.

Liquid crystal display element (TN liquid crystal, STN liquid crystal, ferroelectric liquid crystal, guest host type liquid crystal, cholesteric liquid crystal, etc.) according to the present invention, display by movement of electrophoretic type, electrochromic type, rotating spherical type, rotating cylindrical type, dry powder The format refers to a method of forming an image by liquid crystal alignment, electrophoresis phenomenon, electrochromic phenomenon, spherical and cylindrical member rotation, and powder movement. Hereinafter, the display panel and the manufacturing method thereof according to the present invention will be described using more specific embodiments. However, the present invention is not limited to the embodiments.
The film as the insulating substrate in the present invention is not particularly limited as long as it is a polyimide film having a curl degree of 10% or less at 300 ° C., and an aromatic diamine for obtaining a polyimide film and an aromatic tetra The reaction with the carboxylic acid is obtained by subjecting an aromatic diamine and an aromatic tetracarboxylic acid (anhydride) to a (ring-opening) polyaddition reaction in a solvent to obtain a polyamic acid solution as a polyimide precursor, Next, a precursor film (green film) is formed from this polyamic acid solution, followed by drying, heat treatment, and dehydration condensation (imidization).

Hereinafter, the polyimide film will be described in detail.
Although the polyimide film in this invention is not specifically limited, The combination of the following aromatic diamine and aromatic tetracarboxylic acid (anhydride) is mentioned as a preferable example.
A. A combination of an aromatic diamine having a benzoxazole structure and an aromatic tetracarboxylic acid.
B. A combination of an aromatic diamine having a diaminodiphenyl ether skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid skeleton.
C. A combination of an aromatic diamine having a phenylenediamine skeleton and an aromatic tetracarboxylic acid having a biphenyltetracarboxylic acid skeleton.
D. A combination of one or more of the above ABCs.
Used in a polyimide benzoxazole film mainly composed of polyimide benzoxazole obtained by reacting an aromatic diamine having a benzoxazole structure that can be particularly preferably used in the present invention and an aromatic tetracarboxylic acid anhydride, Examples of aromatic diamines having a benzoxazole structure include the following compounds.

Among these, amino (aminophenyl) benzoxazole isomers are preferable from the viewpoint of ease of synthesis. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above. These diamines may be used alone or in combination of two or more.
In the present invention, it is preferable to use 70 mol% or more of the aromatic diamine having the benzoxazole structure.

The present invention is not limited to the above items, and the following aromatic diamines may be used. Preferably, the diamines do not have the benzoxazole structure exemplified below as long as the total aromatic diamine is less than 30 mol%. Is a polyimide film using one or two or more in combination.
Examples of such diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl]. Sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine,

  3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,4'- Diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl] methane, 1 , 1-Bi [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) phenyl] propane, 1 , 2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl ]propane,

1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [4- (4-aminophenoxy) Phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-aminophenoxy) Phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3-methylphenyl] propane, 2- [4- ( 4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3,5-dimethylphen Le] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane,

1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) ) Biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- ( 4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,3-bis [4- (4-aminophenoxy) ) Benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3 Aminophenoxy) benzoyl] benzene, 4,4′-bis [(3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy) phenyl] propane, 3,4'-diaminodiphenyl sulfide,

2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1 -Bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4 '-Bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [4- (4-amino-α) , Α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis 4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3 -Bis [4- (4-amino-6-fluorophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl Benzene, 1,3-bis [4- (4-amino-6-cyanophenoxy) -α, α-dimethylbenzyl] benzene,

3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-diphenoxybenzophenone, 3,4′-diamino-4,5′-diphenoxybenzophenone, 3, 3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3 '-Diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'- Diamino-4-biphenoxybenzophenone, 4,4′-diamino-5-biphenoxybenzophenone, 3,4 -Diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 1,4-bis (3-amino- 4-phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino) -4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-Amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) pheno Si] benzonitrile and some or all of the hydrogen atoms on the aromatic ring in the aromatic diamine are halogen atoms, alkyl groups having 1 to 3 carbon atoms or alkoxyl groups, cyano groups, or alkyl groups or alkoxyl group hydrogen atoms. Examples thereof include aromatic diamines substituted with a halogenated alkyl group having 1 to 3 carbon atoms, partially or entirely substituted with halogen atoms, or alkoxyl groups.

  The aromatic tetracarboxylic acids used in the present invention are, for example, aromatic tetracarboxylic anhydrides. Specific examples of the aromatic tetracarboxylic acid anhydrides include the following.

These tetracarboxylic dianhydrides may be used alone or in combination of two or more.
In the present invention, one or two or more non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination as long as they are less than 30 mol% of the total tetracarboxylic dianhydrides. Examples of such tetracarboxylic acid anhydrides include butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, and cyclobutanetetracarboxylic acid. Acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2,3 5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-3 -(1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride 1-ethylcyclohexane -(1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane- 1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride,

Bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1 , 3-Dipropylcyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and the like. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  The solvent used when polyamic acid is obtained by polycondensation (polymerization) of the aromatic diamine and aromatic tetracarboxylic acid (anhydride) dissolves both the raw material monomer and the resulting polyamic acid. Although it will not specifically limit if it carries out, A polar organic solvent is preferable, for example, N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, Examples thereof include N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, and halogenated phenols. These solvents can be used alone or in combination. The amount of the solvent used may be an amount sufficient to dissolve the monomer as a raw material. As a specific amount used, the mass of the monomer in the solution in which the monomer is dissolved is usually 5 to 40% by mass, The amount is preferably 10 to 30% by mass.

Conventionally known conditions may be applied for the polymerization reaction for obtaining the polyamic acid (hereinafter also simply referred to as “polymerization reaction”). As a specific example, in a temperature range of 0 to 80 ° C., 10 Stirring and / or mixing continuously for 30 minutes. If necessary, the polymerization reaction may be divided or the temperature may be increased or decreased. In this case, the order of adding both monomers is not particularly limited, but it is preferable to add aromatic tetracarboxylic acid anhydrides to the solution of aromatic diamines. The mass of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). From the viewpoint of the stability of liquid feeding, it is preferably 10 to 2000 Pa · s, and more preferably 100 to 1000 Pa · s.
The reduced viscosity (ηsp / C) of the polyamic acid in the present invention is not particularly limited, but is preferably 3.0 dl / g or more, more preferably 4.0 dl / g or more. By setting these reduced viscosities, It becomes easy to control the linear expansion coefficient of the obtained polyimide benzoxazole to be -5 to 16 (ppm / ° C).

  Vacuum defoaming during the polymerization reaction is effective for producing a high-quality polyamic acid organic solvent solution. Moreover, you may perform superposition | polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction. Examples of the end capping agent include compounds having a carbon-carbon double bond such as maleic anhydride. The amount of maleic anhydride used is preferably 0.001 to 1.0 mol per mol of aromatic diamine.

  As an imidization method by high-temperature treatment, a conventionally known imidation reaction can be appropriately used. For example, using a polyamic acid solution that does not contain a ring-closing catalyst or a dehydrating agent, the imidization reaction proceeds by subjecting it to a heat treatment (so-called thermal ring-closing method), or a polycyclic acid solution containing a ring-closing catalyst and a dehydrating agent In particular, a chemical ring closing method in which an imidization reaction is performed by the action of the above ring closing catalyst and a dehydrating agent can be given.

  100-500 degreeC is illustrated as a heating maximum temperature of a thermal ring closure method, Preferably it is 200-480 degreeC. When the maximum heating temperature is lower than this range, it is difficult to close the ring sufficiently, and when it is higher than this range, the deterioration proceeds and the composite tends to become brittle. A more preferable embodiment includes a two-stage heat treatment in which treatment is performed at 150 to 250 ° C. for 3 to 20 minutes and then treatment at 350 to 500 ° C. for 3 to 20 minutes.

In the chemical ring closure method, imidization reaction of a polyamic acid solution is partially advanced to form a precursor complex having self-supporting property, and then imidization can be performed completely by heating.
In this case, the condition for partially proceeding with the imidization reaction is preferably a heat treatment for 3 to 20 minutes at 100 to 200 ° C., and the condition for allowing the imidization reaction to be completely performed is preferably 200 to 400 ° C. For 3 to 20 minutes.

The timing for adding the ring-closing catalyst to the polyamic acid solution is not particularly limited, and may be added in advance before the polymerization reaction for obtaining the polyamic acid. Specific examples of the ring-closing catalyst include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine, and betapicoline. Among them, heterocyclic tertiary amines are mentioned. At least one amine selected from is preferred. Although the usage-amount of a ring-closing catalyst with respect to 1 mol of polyamic acids does not have limitation in particular, Preferably it is 0.5-8 mol.
The timing of adding the dehydrating agent to the polyamic acid solution is not particularly limited, and may be added in advance before the polymerization reaction for obtaining the polyamic acid. Specific examples of the dehydrating agent include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride. Among them, acetic anhydride, benzoic anhydride, etc. Acids or mixtures thereof are preferred. Moreover, the usage-amount of the dehydrating agent with respect to 1 mol of polyamic acids is not particularly limited, but is preferably 0.1 to 4 mol. When a dehydrating agent is used, a gelation retarder such as acetylacetone may be used in combination.

The polyimide film as the insulating substrate in the substrate for a display device of the present invention is a film having a curl degree at 300 ° C. of 10% or less, and the curl degree of the film at 300 ° C. (hereinafter, curl of the film at 300 ° C.). (Also called degree) means the degree of deformation in the thickness direction with respect to the surface direction of the film after performing a predetermined heat treatment. Specifically, as shown in FIG. After 10 minutes of hot air treatment at 300 ° C., the test piece is left on the plane so as to be concave, and the average value of distances from the four corner planes (h1, h2, h3, h4: unit mm) is the curl amount. (Mm), which is a value expressed as a percentage (%) of the curl amount with respect to the distance (35.36 mm) from each vertex to the center of the test piece.
Samples were sampled at a total of 10 points, with 2 points in the width direction (1/3 and 2/3 of the length) as the center points of the test piece at a 1/5 length pitch with respect to the total length of the film. The measured value is an average value of 10 points.
However, if there is not enough film to sample 10 points, sample as much as possible.
Specifically, it is calculated by the following formula.
Curling amount (mm) = (h1 + h2 + h3 + h4) / 4
Curling degree (%) = 100 × (curl amount) /35.36

In the present invention, the curl degree at 400 ° C. of the polyimide film is measured in the same manner except that the heat treatment at the time of measurement at 300 ° C. is treated with hot air at 400 ° C. for 10 minutes.
The curl degree at 300 ° C. in the present invention is more preferably 8% or less, still more preferably 5% or less, and further a film having a curl degree at 400 ° C. of 10% or less is preferred.
The substrate film in the substrate for a display device in the present invention is preferably a polyimide film, more preferably a polyimide benzoxazole obtained by reacting an aromatic diamine having a benzoxazole structure with an aromatic tetracarboxylic acid. Is a polyimide film having a linear expansion coefficient of -5 to 16 ppm / ° C., and particularly preferably an aromatic diamine having a benzoxazole structure and an aromatic tetracarboxylic acid (anhydride). And a polyimide film having a plane orientation coefficient of 0.75 or more, a tensile modulus of elasticity of 5 GPa or more, and a tensile strength at break of 300 MPa or more.

The linear expansion coefficient in the longitudinal direction (MD direction) and the width direction (TD direction) of the polyimide benzoxazole film of the present invention is preferably −5 to 16 ppm / ° C. (× 10 ⁻⁶ cm / cm / ° C.), It is still more preferable that it is 2-10 ppm / degrees C, and it is especially preferable that it is 3-9 ppm / degrees C. These linear expansion coefficients depend on the types and ratios of diamine and tetracarboxylic acid anhydride and the plane orientation coefficient. The linear expansion coefficient can be lowered by increasing the diamine component having a benzoxazole structure, and can be within a predetermined range by using 50% or more of the total diamine component and a diamine having a benzoxazole structure.
Even if the linear expansion coefficient deviates from this range in any direction, the stress applied to the semiconductor layer increases, and the photoelectric conversion efficiency is significantly reduced. That is, when the semiconductor thin film is formed, the substrate is heated at a predetermined temperature. When the substrate is cooled to room temperature, it corresponds to the difference between the linear expansion coefficient of the semiconductor thin film and the linear expansion coefficient of the base film. Stress is applied to both the semiconductor and the base film. As described above, the stress applied to the semiconductor layer not only decreases the photoelectric conversion efficiency but also decreases the lifetime and reliability of the element itself. At the same time, the stress applied to the substrate side inhibits the adhesion between the substrate and the semiconductor thin film.
Further, when the polyimide film has a plane orientation coefficient of 0.75 or more, a tensile modulus of elasticity of 5 GPa or more, and a tensile breaking strength of 300 MPa or more, a further effect of improving heat resistance can be obtained.

It is preferable that the tensile elasticity modulus of the longitudinal direction (MD direction) and the width direction (TD direction) of the polyimide benzoxazole film in this invention is 5 GPa or more. When the tensile modulus is less than this range, the film is likely to be deformed by an external force, and as a result, the semiconductor thin film formed on the film surface is likely to be broken or defective. The tensile modulus is preferably 7 GPa or more, more preferably 9 GPa or more. The upper limit of the tensile elastic modulus is not particularly limited, but is practically about 25 GPa.
The tensile elastic modulus of the polyimide benzoxazole film can be controlled by the molecular structure and the plane orientation. The tensile modulus depends on the molecular structure, that is, the type and proportion of diamine and tetracarboxylic anhydride, and the density. The tensile elastic modulus can be increased by increasing the diamine component having a benzoxazole structure and can be within a predetermined range by using diamine having a benzoxazole structure of 50% or more of the total diamine component. The control of the plane orientation coefficient generally includes means for adjusting the temperature rising profile at the time of forming the green film, imidizing, or performing stretching before the means, and the means for the film of the present invention. Can be applied. For example, in order to increase the plane orientation coefficient of a polyimide benzoxazole film, the amount of heat applied to the green film can be reduced, or the film can be stretched in the vertical, horizontal, or both horizontal and vertical directions before or during the imidization reaction. The means to do is mentioned.

The tensile rupture strength in the longitudinal direction (MD direction) and the width direction (TD direction) of the polyimide benzoxazole film of the present invention is preferably 300 MPa or more. When the tensile strength at break is less than this range, the external force tends to damage not only the film substrate but also the semiconductor layer. The upper limit is not particularly limited. The tensile strength at break of the polyimide benzoxazole film can be achieved by keeping the molecular weight of the polyamic acid and the degree of hydrolysis of the amide bond from the green film preparation to the imidization step within a predetermined range.
More specifically, the reduced viscosity of the polyamic acid solution is 1.2 or more, preferably 1.5 or more, more preferably 1.7 or more, and further, imidation is started from the time when the polyamic acid solution is applied to the support. By setting the relative humidity of the working atmosphere until completion to 75% RH or less, preferably 60% RH or less, more preferably an inert gas atmosphere, a predetermined tensile breaking strength can be realized.

The imidization method preferably used in the present invention is a thermal ring closure method as described above. The thermal ring closure method is a method in which polyamic acid is imidized by heating. In the present invention, the polyamic acid solution may contain a ring-closing catalyst and a dehydrating agent, and the imidization reaction may be promoted by the action of the ring-closing catalyst and the dehydrating agent. In this method, after the polyamic acid solution is applied to the support, the imidization reaction is partially advanced to form a film having self-supporting property, and then imidization can be performed completely by heating.
The timing for adding the ring-closing catalyst to the polyamic acid solution is not particularly limited, and may be added in advance before the polymerization reaction for obtaining the polyamic acid. Specific examples of the ring-closing catalyst include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine, and betapicoline. Among them, heterocyclic tertiary amines are mentioned. At least one amine selected from is preferred. Although the usage-amount of a ring-closing catalyst with respect to 1 mol of polyamic acids does not have limitation in particular, Preferably it is 0.5-8 mol.

  The timing of adding the dehydrating agent to the polyamic acid solution is not particularly limited, and may be added in advance before the polymerization reaction for obtaining the polyamic acid. Specific examples of the dehydrating agent include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride. Among them, acetic anhydride, benzoic anhydride, etc. Acids or mixtures thereof are preferred. Moreover, the usage-amount of the dehydrating agent with respect to 1 mol of polyamic acids is although there is no limitation in particular, Preferably it is 0.1-4 mol. When a dehydrating agent is used, a gelation retarder such as acetylacetone may be used in combination.

The polyimide film precursor (green film) formed on the support may be peeled off from the support before complete imidization, or may be peeled off after imidization.
Furthermore, in the present invention, a lubricant can be added to improve the productivity, winding property and operability of the film. As the lubricant, inorganic or organic fine particles typified by metal oxides such as silica and alumina and inorganic salts can be used. The particle diameter of the lubricant that can be preferably used is in the range of 0.01 to 10 μm, and the amount added is in the range of about 0.001 to 1% of the entire film.

The polyimide benzoxazole film in the present invention is usually an unstretched film, but may be uniaxially or biaxially stretched. Here, the unstretched film refers to a film obtained without intentionally applying a mechanical external force in the surface expansion direction of the film by tenter stretching, roll stretching, inflation stretching, or the like.
When the polyimide benzoxazole film in the present invention is used as it is or is not treated with a surface treatment agent or a surface activator, it is preferably a corona discharge treatment, a low pressure or normal pressure plasma treatment, a vacuum plasma treatment, an ultraviolet irradiation, a flame. Surface treatment is performed by treatment or the like.

Next, an organic EL display device (panel) as an example of application of the substrate for a display device of the present invention will be described. As described above, a polyimide (benzoxazole) film is laminated and patterned with a conductive layer to be a back electrode, a functional thin film of a semiconductor layer made of thin film silicon to be a drive circuit or a switching element, and a functional thick film. It is realized by.
First, a first electrode is formed on a film (substrate). The first electrode need not be transparent. In most cases, a metal thin film is used and may be appropriately selected in consideration of compatibility with the organic material used. In a general organic EL device, a metal thin film often functions as an electron injection electrode. Therefore, a metal having a small work function that facilitates electron injection is desirable. Specifically, aluminum, magnesium, lithium, Examples include calcium. Conversely, when a metal thin film functions as a hole injection electrode, a metal having a large work function that facilitates hole injection is desirable. Specific examples include gold, platinum, copper, and nickel.
As a method for forming the first electrode, a known method can be applied, and examples thereof include a vapor deposition method, a sputtering method, an electron beam method, and a plating method. Further, patterning is not particularly limited, and a known shadow mask method, photolithography method, and the like can be applied.
Although the film thickness of a 1st electrode is based also on the metal material to be used, it is about 500 to 1 micrometer.
Next, an active drive TFT (thin film transistor) is formed on the substrate.
The organic EL display device (panel) which is an example of the present invention has a configuration in which light emission is extracted from the second electrode side, so there is no need to be particularly conscious of transparency, and it can be made from amorphous silicon, polysilicon or the like by a known method. The TFT to be formed may be formed. Also, MIM (Metal Insulator Metal Structure Diode) may be used instead of TFT. Further, the TFT may be a channel etch type, a channel protection type, a stagger type, an inverted stagger type, or other known semiconductor technology.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by a following example. In addition, the evaluation method of the physical property in the following examples is as follows.

1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. using an Ubbelohde type viscosity tube.
2. The thickness of the film was measured using a micrometer (Finereuf, Millitron (trade name) 1254D).

3. Tensile modulus, tensile breaking strength and tensile breaking elongation of the film The film to be measured was cut into strips of 100 mm × 10 mm in the flow direction (MD direction) and the width direction (TD direction), respectively, as test pieces. . Using a tensile tester (manufactured by Shimadzu Corporation, Autograph (trade name), model name AG-5000A) under the conditions of a tensile speed of 50 mm / min and a distance between chucks of 40 mm, the tensile modulus of elasticity in each of the MD direction and TD direction, Tensile rupture strength and tensile rupture elongation were measured.

4). Film linear expansion coefficient (CTE)
For the film to be measured, the stretch rate in the MD direction and the TD direction is measured under the following conditions, and the stretch rate / temperature at intervals of 30 ° C. to 45 ° C., 45 ° C. to 60 ° C.,. This measurement was performed up to 300 ° C., and the average value of all measured values was calculated as CTE. The meanings of the MD direction and the TD direction are the same as in the measurement of “3.” above.
Device name: TMA4000S manufactured by MAC Science
Sample length; 20mm
Sample width: 2 mm
Temperature rise start temperature: 25 ° C
Temperature rising end temperature: 400 ° C
Temperature increase rate: 5 ° C / min
Atmosphere: Argon

5. The melting point of the film and the glass transition temperature The film to be measured was subjected to differential scanning calorimetry (DSC) under the following conditions, and the melting point (melting peak temperature Tpm) and the glass transition point (Tmg) were determined according to JIS K 7121. .
Device name: DSC3100S manufactured by MAC Science
Pan ： Aluminum pan (non-airtight)
Sample mass: 4mg
Temperature rising start temperature: 30 ° C
Temperature rising end temperature: 600 ° C
Temperature increase rate: 20 ° C / min
Atmosphere: Argon

6). Thermal Decomposition Temperature of Film Using a sufficiently dried film to be measured as a sample, thermobalance measurement (TGA) was performed under the following conditions, and the temperature at which the mass of the sample decreased by 5% was regarded as the thermal decomposition temperature.
Device name: TG-DTA2000S manufactured by MAC Science
Pan ： Aluminum pan (non-airtight)
Sample mass: 10 mg
Temperature rising start temperature: 30 ° C
Temperature increase rate: 20 ° C / min
Atmosphere: Argon

7). Plane orientation coefficient of film A film to be measured was mounted on a measurement jig and X-ray diffraction measurement was performed under the following conditions to obtain a pole figure of a diffraction peak appearing near 2θ = 21.8 °.
Device name: RINT 2100PC manufactured by Rigaku Co., Ltd., multipurpose sample base Voltage, current value; 40 kV, 40 mA
Measurement method; reflection method and transmission method scanning range; reflection method α; 15 to 90 ° / 2.5 ° interval
β: 0 to 360 ° / 5 ° interval
Reflection method α: 0-15 ° / 2.5 ° interval
β: 0-360 ° / 5 ° interval slit; DS 0.1 mm, SS 7 mm, RS 7 mm,
Vertical divergence limit slit 1.2mm
Scanning speed: Continuous (360 ° / min)
Detector: Scintillation counter

FIG. 2 schematically shows this pole figure. In the figure, peak half widths (HMD and HTD) were determined from diffraction intensity profiles at two broken lines, and the average value of HMD and HTD was defined as Ha (unit: °). The peak half-value width was obtained using a Rigaku analysis program. From the thus obtained Ha, the plane orientation coefficient of the polyimide benzoxazole film was calculated by the following formula.
Plane orientation coefficient = (180 °-Ha) ÷ 180 °

[Polymeric acid solution polymerization example 1]
(Preliminary dispersion of inorganic particles)
1.22 parts by mass of amorphous silica spherical particles Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 420 parts by mass of N-methyl-2-pyrrolidone, the wetted part of the container, and the infusion pipe are austenitic stainless steel The mixture was placed in a container of SUS316L and stirred with a homogenizer T-25 basic (manufactured by IKA Labortechnik) at a rotation speed of 1000 rpm for 1 minute to obtain a preliminary dispersion. The average particle size in the preliminary dispersion was 0.11 μm.
(Preparation of polyamic acid solution)
A nitrogen inlet tube, a thermometer, a liquid contact part of a container equipped with a stirring rod, and a pipe for infusion were substituted with nitrogen in the reaction container made of austenitic stainless steel SUS316L, and then 223 parts by mass of 5-amino-2- ( p-Aminophenyl) benzoxazole was added. Next, 4000 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, and then the preliminary dispersion obtained above was added with 420 parts by mass and 217 parts by mass of pyromellitic dianhydride. When the mixture was stirred at ° C. for 24 hours, a brown viscous polyamic acid solution A was obtained. The reduced viscosity (ηsp / C) was 3.8 dl / g.

[Polymeric acid solution polymerization example 2]
Nitrogen introduction tube, thermometer, vessel wetted part equipped with stirring rod, and infusion pipe were replaced with nitrogen in the reaction vessel of austenitic stainless steel SUS316L, and then 5-amino-2- (p-aminophenyl) ) After adding 223 parts by mass of benzoxazole and 4416 parts by mass of N, N-dimethylacetamide and completely dissolving them, Snowtex DMAC-ST30 (manufactured by Nissan Chemical Industries, Ltd.) 40 in which colloidal silica is dispersed in dimethylacetamide .5 parts by mass (including 8.1 parts by mass of silica) and 217 parts by mass of pyromellitic dianhydride are added and stirred at a reaction temperature of 25 ° C. for 24 hours to obtain a brown and viscous polyamide acid solution B. It was. Ηsp / C of this product was 4.0 dl / g.

[Polymeric acid solution polymerization example 3]
(Preliminary dispersion of inorganic particles)
7.6 parts by weight of amorphous silica spherical particle Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 390 parts by weight of N-methyl-2-pyrrolidone, the liquid contact part of the container, and the infusion pipe are austenitic stainless steel SUS316L And stirred for 1 minute at a rotation speed of 1000 rpm with a homogenizer T-25 basic (manufactured by IKA Labortechnik) to obtain a preliminary dispersion.
(Preparation of polyamic acid solution)
The liquid contact part of the vessel equipped with a nitrogen introduction tube, a thermometer, a stirring rod, and the pipe for infusion were substituted with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 200 parts by mass of diaminodiphenyl ether was added. Next, after 3800 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 390 parts by mass and 217 parts by mass of pyromellitic dianhydride were added to the preliminary dispersion obtained above. When the mixture was stirred at 0 ° C. for 5 hours, a brown viscous polyamic acid solution C was obtained. The reduced viscosity (ηsp / C) was 3.7 dl / g.

[Polymeric acid solution polymerization example 4]
(Preliminary dispersion of inorganic particles)
3.7 parts by mass of amorphous silica spherical particles Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 420 parts by mass of N-methyl-2-pyrrolidone, and the infusion part are austenitic stainless steel SUS316L And stirred for 1 minute at a rotation speed of 1000 rpm with a homogenizer T-25 basic (manufactured by IKA Labortechnik) to obtain a preliminary dispersion.
(Preparation of polyamic acid solution)
The wetted part of the vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod, and the infusion piping were substituted with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 108 parts by mass of phenylenediamine was added. Next, after 3600 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 420 parts by mass and 292.5 parts by mass of diphenyltetracarboxylic dianhydride were added to the preliminary dispersion obtained above. When the mixture was stirred at 25 ° C. for 12 hours, a brown viscous polyamic acid solution D was obtained. The reduced viscosity (ηsp / C) was 4.5 dl / g.

[Production Examples 1 to 4 of polyimide film]
The polyamic acid solution obtained in Polymerization Examples 1 to 4 was coated on the non-lubricant surface of polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) using a comma coater (gap: 650 μm, coating width). 1240 mm) and passed through a continuous drying furnace having four drying zones and dried under the following predetermined conditions.
Zone 1 Upper temperature 105 ° C, Lower temperature 110 ° C
Air volume 20 cubic m / min for both top and bottom Zone 2 Upper temperature 110 ° C, Lower temperature 110 ° C
Air volume 30 cubic m / min for both top and bottom Third zone Upper temperature 110 ° C, Lower temperature 110 ° C
Air volume 20 cubic m / min for both top and bottom Zone 4 Upper temperature 110 ° C, Lower temperature 110 ° C
Upper air volume 15 cubic m / min, lower air volume 20 cubic m / min The length of each zone is the same, and the total drying time is 15 minutes.
The air volume is the sum of the air volumes from the outlets for each zone.
The polyamic acid film that became self-supporting after drying was peeled off from the polyester film, and both ends were cut to obtain respective green films having a thickness of 39 μm and a width of 1200 mm.
The obtained green film was passed through a continuous heat treatment furnace purged with nitrogen while holding both ends with a pin tenter. As the second stage, two stages of heating were performed at 400 ° C. for 5 minutes to advance the imidization reaction. Then, it cooled to room temperature in 5 minutes, and the 25-micrometer-thick polyimide film which exhibits brown was obtained. The properties of the obtained film are shown in Table 1.

[Production Example 5 of polyimide film]
A stainless steel belt obtained by polishing the polyamic acid solution obtained in Polymerization Example 2 to a thickness of 0.5 mm, a width of 750 mm, and a surface roughness of 0.005 μm was coated with a squeegee / belt gap of 680 μm, and three hot-air drying zones First zone Temperature: 105 ° C, Air volume: 10 cubic m / min Drying time: 4 minutes Second zone Temperature: 115 ° C, Air volume: 20 cubic m / min Drying time: 4 minutes Third zone Temperature: 110 ° C., temperature: 25 cubic m / min Drying time: dried for 4 minutes. The polyamic acid film which became self-supporting after drying was peeled from the stainless steel belt to obtain a green film having a thickness of 39 μm.
The obtained green film was passed through a continuous heat treatment furnace purged with nitrogen, the first stage was heated at 180 ° C. for 3 minutes, and the heating rate was 4 ° C./second, and the second stage was at 460 ° C. for 2 minutes. The imidation reaction was allowed to proceed by applying two stages of heating under the conditions described above. Then, it cooled to room temperature in 5 minutes, and the 25-micrometer-thick polyimide film which exhibits brown was obtained. The properties of the obtained film are shown in Table 1.

[Production Examples 6 to 9 of polyimide film]
A stainless steel belt obtained by polishing the polyamic acid solution obtained in Polymerization Examples 1 to 4 to a thickness of 0.5 mm, a width of 750 mm, and a surface roughness of 0.005 μm was coated with a squeegee / belt gap of 680 μm, and three hot-air types First zone Temperature: 110 ° C., Air volume: 10 cubic m / min Drying time: 2 minutes Second zone Temperature: 130 ° C., Air volume: 25 cubic m / min Drying time: 2 minutes 3 zones Temperature: 135 ° C., temperature: 25 cubic m / min Drying time: dried for 2 minutes. The polyamic acid film which became self-supporting after drying was peeled from the stainless steel belt to obtain a green film having a thickness of 36 μm.
The obtained green film was passed through a continuous heat treatment furnace purged with nitrogen, the first stage was heated at 180 ° C. for 3 minutes, and the heating rate was 4 ° C./second, and the second stage was at 460 ° C. for 2 minutes. The imidation reaction was allowed to proceed by applying two stages of heating under the conditions described above. Then, it cooled to room temperature in 5 minutes, and the 25-micrometer-thick polyimide film which exhibits brown was obtained. The properties of the obtained film are shown in Table 1.

As an example of manufacturing a display panel, a structure as shown in FIG. 3 is used.
On the insulating substrate, Al is formed by sputtering at 200 nm and patterned to form a gate wiring bus line, a gate electrode, and a gate wiring. At this time, each gate wiring is connected to the gate wiring bus line. This gate wiring bus line is used as a power supply line during anodization. Thereafter, 3 μm of photoresist is applied, and the resists in the regions A and B are removed by a photoetching process. Region A is a TFT portion and a Bha wiring intersection. In this state, the substrate is immersed in a chemical conversion solution, and a voltage of +72 V is applied to the gate line bus line for 30 minutes, so that 70 nm of Al in the regions A and B becomes Al ₂ O ₃ , and an Al of about 100 nm is obtained. _{A 2} O ₃ film is obtained. As a chemical conversion solution, a 3% tartaric acid solution was diluted with ethylene glycol, and ammonia water was added to adjust the pH to 7.0. After removing the resist, heating is performed in the atmosphere at 200 ° C. for 1 hour. This is intended to reduce the leakage current of the Al ₂ O ₃ film.
On top of this, 300 nm of silicon nitride is formed by plasma CVD, and 100 nm of hydrogenated amorphous silicon (a-Si) and 200 nm of second silicon nitride are formed. The substrate temperature at this time was 380 ° C. After this, the second silicon nitride was patterned so that only the wiring intersections were on the TFT channel.
Next, an amorphous silicon n layer doped with about 2% phosphorus is deposited to a thickness of 50 nm and patterned, leaving only the TFT source and drain portions. At this time, a-Si is also removed at the same time. Cr is deposited to 100 nm and Al is deposited to 500 nm by sputtering and patterned to form signal lines, TFT drains, source wires, and the like. The gate wiring bus lines previously formed at the time of this Al processing are removed to separate each gate wiring.
Next, ITO as a transparent electrode is formed by 100 nm sputtering to form pixel electrodes, terminals, and the like. Finally, about 1 μm of silicon nitride is deposited by plasma CVD,
The silicon nitride in the terminal portion is removed by a photoetching process to complete the TFT substrate.
A light emitting layer is formed on the pixel electrode. Here, an organic layer containing poly (para-phenylene vinylene) which is not doped as a light-emitting substance was formed by a screen printing method. The drying temperature of the membrane is a maximum of 180 ° C. Finally, ITO was sputtered on the light emitting layer as a second electrode, and a fluororesin coating was applied to form a protective film, thereby producing a display device using an organic EL element. At this time, the substrate temperature is heated to 350 ° C.
When an alternating voltage of 1000 Hz with a peak-to-peak of 60 V was applied to the organic EL element-use display device using the obtained film of Production Example 1, light was emitted in bright green (described as bright green or green in Table 1). Similarly, a self-luminous display device was manufactured using other films, and the luminous efficiency was measured and compared. The results are shown in Table 1.
As is apparent from the results shown in Table 1, good light emission was obtained in the display device of the example, but sufficient light emission was not obtained in the display device of the comparative example (in Table 1, dark green or Described as not emitting light). This is presumed to be because the conductive layer, particularly the transparent conductive layer, was damaged due to inferior flatness maintenance at a high temperature of the film used by increasing and decreasing the temperature during the process.

「反り」は、カール度測定時に常温（加熱なし）で評価した値である。

“Warpage” is a value evaluated at normal temperature (no heating) when measuring the curl degree.

  As described above, the display device of the present invention is a polyimide film having a curl degree of 10% or less at 300 ° C., mainly composed of polyimide obtained by reacting aromatic diamines and aromatic tetracarboxylic acids. Is a substrate for a display device, in which a semiconductor thin film element and a thin film for wiring are directly formed on the surface of the polyimide film insulating base, and the curl degree at 300 ° C. as the insulating base Since a polyimide (benzoxazole) film with 10% or less is used, it has excellent flatness maintenance due to high temperatures, resulting in misalignment with the circuit, lower connection reliability between terminals, and stress in conductive materials and semiconductor chips. Since defects such as cracks caused by strain are suppressed due to temperature changes in the usage environment, the reliability of the thin film display device is improved. In are those very useful, it is large to contribute to the industry.

It is the schematic diagram which showed the measuring method of the curl degree of a film. (A) is a top view, (b) is a sectional view indicated by aa in (a) before hot air treatment, and (c) is indicated by aa in (a) after hot air treatment. It is sectional drawing. It is the figure which showed typically the X-ray-diffraction pole figure of the polyimide benzoxazole film. 1 is a schematic conceptual diagram of a thin film (self-luminous type) display device of the present invention. It is a schematic conceptual diagram of the display apparatus of this invention.

Explanation of symbols

(References in FIG. 1 below)
1. 1. (Polyimide) film test piece Alumina / Ceramic plate (Reference in Fig. 3)
1. Substrate (support)
2. Al
3. Anodized film (Al ₂ O ₃ )
4). Silicon nitride (1)
5. 5. Hydrogenated amorphous silicon Silicon nitride (2)
7). Amorphous silicon n layer 8. Cr
9. Gate wiring 10. Signal line 11. Gate wiring bus line 12. Transparent electrode A TFT part B Wiring crossing part (hereinafter, reference numerals in FIG. 4)
1. Substrate (support)
2. First electrode Light emitting layer 4. Second electrode 5. Bulkhead 6. Protective film

Claims (5)

  A polyimide film having a curl degree of 10% or less at 300 ° C., which is mainly composed of polyimide obtained by reacting aromatic diamines and aromatic tetracarboxylic acids, is used as an insulating base, and the surface of the polyimide film insulating base And a substrate for a display device, wherein a semiconductor thin film element and a wiring thin film are directly formed.   The display element is a liquid crystal display element, an EL display element, an electrophoretic display element, an electrochromic display element, a redox type display element, a rotating sphere type or rotating cylindrical type display element, and a display type by moving a dry powder. 2. The substrate for a display device according to claim 1, wherein the substrate is one or more display elements selected from any one of the display elements. The substrate for a display device according to claim 2, wherein the liquid crystal display element is at least one liquid crystal display element selected from TN liquid crystal, STN liquid crystal, ferroelectric liquid crystal, guest-host type liquid crystal, and cholesteric liquid crystal.   The insulating base material is a polyimide film having a linear expansion coefficient of −5 to 16 ppm / ° C. mainly composed of polyimide benzoxazole obtained by reacting an aromatic diamine having a benzoxazole structure with an aromatic tetracarboxylic acid. The substrate for display apparatuses in any one of Claims 1-3.   A plane orientation coefficient mainly composed of polyimide benzoxazole obtained by reacting an aromatic diamine having an benzoxazole structure with an aromatic tetracarboxylic acid as an insulating substrate is 0.75 or more, and a tensile modulus is The substrate for a display device according to any one of claims 1 to 4, wherein the substrate is a polyimide film having 5 GPa or more and a tensile breaking strength of 300 MPa or more.

Images