JP6703160B2 - Flexible electronic device manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a flexible electronic device, which includes a substrate having excellent thermal conductivity such as a display device such as a liquid crystal display, an organic EL display, electronic paper, or a light receiving device such as a light receiving element of a thin film solar cell. And a method suitable for manufacturing various flexible electronic devices.

Currently, in the field of electronic devices such as flat panel displays and electronic papers, glass substrates are mainly used, but glass substrates are heavy and easily broken, and there is a problem that strength decreases when they are made lightweight and thin. Many studies are being conducted to realize a flexible electronic device in which a resin material is replaced. A resin substrate having higher toughness than a glass substrate is being studied for application to a flexible display panel that can be bent and rolled. However, many of these techniques have not been mass-produced because they require new production techniques and equipment.

In recent years, as a method of manufacturing a flat panel display, a method of using a material in which a resin layer is provided on a thin glass substrate has been proposed as a material that is lightweight and resistant to breakage. That is, a laminated body in which a resin layer is formed on a glass substrate is produced, and a thin film transistor (hereinafter, referred to as TFT), a transparent electrode, or the like is formed on the resin surface, which can be used as a display member. In addition, as a method for producing a member for a flexible electronic device, a method of heating the glass substrate with a laser or providing a peeling layer after forming a thin film transistor, a transparent electrode, or the like on the resin surface of the laminate, and peeling and removing (hereinafter , Lift-off method) has been proposed. (Patent documents 1-3, etc.).

A lift-off method has been proposed as a method for manufacturing a flexible electronic device member, and a resin layer can be peeled from a glass substrate by irradiating the glass substrate with an ultraviolet laser beam (Patent Document 1). The ultraviolet laser light irradiates a wavelength exceeding 200 nm. However, there are potential problems with utilizing the heating effect in lifting off the resin layer from the glass substrate. Sufficient energy is required to cause lift-off, but in this case, it is necessary to prevent damage to the resin substrate or members formed thereon due to the effect of thermal expansion.

As a method for manufacturing a member for a flexible electronic device, for example, as disclosed in Patent Document 2, a peel-off layer having different adhesion is provided between a glass substrate and a resin layer to perform lift-off from the glass substrate. However, parylene and cyclic olefin copolymer have a problem that they cannot be used in the annealing process of TFT because of their low heat resistance.

Further, also in Patent Document 3, a method of providing a peeling layer between a glass substrate and a resin substrate for peeling is examined, but since the peeling layer is provided by vapor deposition or coating, the process becomes complicated and essential production is performed. It does not improve sex.

On the other hand, the flexible electronic device member is required to have high heat dissipation, and how to dissipate heat generated from the organic light emitting element from the device is an important issue.

An organic light emitting device emits light when a voltage corresponding to a display pattern is applied to the light emitting device by applying a voltage between the electrodes, but at present, part of the light is converted into heat energy when the light emitting device emits Joule heat. It may cause heat generation. It is said that heat generation of the organic light emitting element may cause deterioration of light emitting characteristics such as brightness and deterioration of the organic light emitting element itself. In addition, the higher the temperature of the organic light emitting device, the more likely it is that characteristics of the organic light emitting device deteriorate.

Problems caused by excessive heat generation of the element include, for example, an afterimage and a burn-in phenomenon. As described above, since the current corresponding to the display pattern flows through the light emitting element, there are a portion where a large amount of current flows and a portion where a small amount of current flows depending on the display pattern, and the amount of heat generated varies depending on the display pattern. Therefore, when the fixed pattern is continuously displayed for a long time, the heat generation amount of the organic light emitting element is locally different, and an afterimage or burn-in occurs on the display screen. Afterimages, the fixed pattern gradually disappears, but with burn-in, the fixed pattern does not permanently disappear. Therefore, the afterimage and image sticking of the fixed pattern result in deterioration of image quality. Therefore, in order to prevent a local difference in the amount of heat generated, it is necessary to quickly diffuse the heat to the outside and make the amount of heat generated by the entire organic light emitting element uniform, so that the heat generated by the organic light emitting element is radiated to the outside of the element. Various measures have been studied.

Another problem caused by excessive heat generation of the element is variation in brightness. For example, when the entire screen is displayed in white for a long time, there are portions that are likely to be dissipated and portions that are difficult to dissipate due to differences in the organic light emitting element structure, the housing structure for storing the organic light emitting element, and the like. As a result, a difference in light emission characteristics may occur due to a local temperature difference, and the brightness of the display screen may vary. In order to make the brightness of the display screen uniform, it is necessary that the locally generated heat be evenly diffused and released to the outside.

Various techniques have been taken to solve the problems caused by excessive heat generation of these elements.

As a method of improving heat dissipation, a highly heat-conductive substrate made of glass, metal, or ceramic material, heat dissipation by a fan or water cooling, increase in surface area due to unevenness, and a layer such as a film or sheet are provided to move from the substrate to the outside. There has been proposed a method for significantly improving the heat radiation of the organic light emitting device and suppressing the temperature rise of the organic light emitting device. (Patent Document 4)

Generally, the thermal conductivity of glass is as low as 1 W/m·K, so that the generated heat is difficult to conduct from the inside to the outside of the glass. Further, since it is difficult for the glass to uniformly dissipate heat, uneven heat distribution occurs in the glass substrate, which causes differences in characteristics such as variations in brightness and changes in service life over time in the organic light emitting element and the device in which it is mounted. It may end up.

In Patent Document 5, a study using a metal substrate as a support is also conducted, but in the embodiment, a Cu substrate having a thickness of 2 mm is used, which makes it difficult to make it flexible or thin. Further, in Patent Document 5, heat dissipation using an increase in surface area due to unevenness is also examined, but the heat dissipation complicates the structure and lowers the production efficiency.

A study using a ceramic substrate as an organic light emitting element substrate was also conducted (Patent Document 6), but there was a drawback that it could not be applied to a flexible device. A flexible electronic device substrate containing a filler has also been investigated (Patent Document 7), but no investigation has been conducted so far as an organic light emitting element substrate. Neither the dimensional stability nor the coefficient of thermal expansion involved in peeling during manufacturing has been examined, and the anisotropy of thermal conductivity in the plane direction and the longitudinal direction is not described.

Substrates using a composite of a resin and a filler for a flexible electronic device substrate are also under study for production, but these have the effect of increasing mechanical strength and lowering the coefficient of thermal expansion. For example, in Patent Document 3 and Patent Document 8, a glass filler having low thermal conductivity is used, and in Patent Document 9, colloidal silica is used, but colloidal silica also contains a filler because it has low thermal conductivity. However, there is a problem that heat cannot be radiated from the flexible electronic device substrate.

Japanese Patent No. 5033880 JP, 2010-67957, A JP, 2012-60103, A Japanese Patent No. 2945195 WO2009/066561 JP-A-63-34884 JP, 2008-7590, A WO2011/033751 WO2013/161970

When the existing material (metal/ceramic) with thermal conductivity up to now is used for the support, the flexible electronic device substrate cannot be peeled from the support or the shape can be maintained even if peeled. However, the flexible electronic device substrate having thermal conductivity cannot be manufactured by the lift-off method because there is a problem in that it does not exist or the performance is deteriorated due to distortion with other members during peeling.

Lift-off of flexible electronic device substrates made of glass filler or colloidal silica and resin has been studied, but this is aimed at enhancing the thermal expansivity and mechanical strength, and the biggest problem of organic light-emitting devices is heat It was difficult to solve the problem.

Therefore, it is an object of the present invention to provide a method of manufacturing a flexible electronic device, which allows a flexible electronic device to be manufactured without breakage and which can be easily peeled off between a support and a heat conductive substrate after the manufacturing.

In addition, the object of the present invention is to enable thinning, light weight, and flexibility, and for example, to uniformly disperse the heat distribution of the organic light emitting device generated over time to the outside, thereby An object of the present invention is to provide a method of manufacturing a flexible electronic device capable of preventing afterimages and image sticking and exhibiting a long life and excellent performance.

The present inventor, as a result of repeated studies to solve the above problems, in a method of manufacturing a flexible electronic device, peeling from a member adjacent to the device or damage or distortion of the member itself does not occur, and a good shape is maintained. The inventors have found a method capable of easily peeling between the support and the heat conductive substrate in such a state, and completed the present invention.
In this specification, a step of applying a heat conductive resin material composed of a resin and a filler to a support to produce a laminate composed of the heat conductive substrate and the support, and a step of forming a device layer on the heat conductive substrate. , And a method for manufacturing a flexible electronic device including a step of separating a support and a heat conductive substrate.

That is, according to the present invention, a heat conductive resin material containing 30 to 80 wt% of a heat conductive filler in a polyimide resin is applied to a metal support to manufacture a laminate substrate composed of the heat conductive resin substrate and the metal support. And a step of forming a device layer on the heat conductive resin substrate of the laminated substrate, the method for manufacturing a flexible electronic device.
Here, as described below, the metal support can be used as a laminate substrate integrated with the heat conductive substrate without being peeled off from the heat conductive substrate. In the case of such an integrated laminated body substrate, the laminated body substrate is composed of a heat conductive resin substrate and a metal support (metal substrate).

In the method for manufacturing a flexible electronic device, the thermal conductivity λxy in the plane direction of the thermal conductive substrate is 0.7 W/mK or more, and the thermal conductivity λz in the thickness direction is 0.3 W/mK or more. Is preferred.

また、上記フレキシブル電子デバイスの製造方法において、支持体と熱伝導性基板の熱膨張係数差が１５ｐｐｍ／Ｋ以下であり、熱伝導性基板とデバイス層の熱膨張係数差が１５ｐｐｍ／Ｋ以下であるのが好ましい。
また、上記フレキシブル電子デバイスの製造方法において、熱伝導性基板が２層以上のポリイミド樹脂からなる多層構造であり、少なくとも１層が熱伝導性フィラーを含有する熱伝導層であると共に、デバイス層と接する側の層は、表面が平滑な平滑層であるのが好ましい。 Further, in the above-described method for manufacturing a flexible electronic device, it is preferable that the heat conductive substrate contains the polyimide resin represented by the above formula (1).

In the method for manufacturing a flexible electronic device, the difference in thermal expansion coefficient between the support and the heat conductive substrate is 15 ppm/K or less, and the difference in thermal expansion coefficient between the heat conductive substrate and the device layer is 15 ppm/K or less. Is preferred.
Further, in the above-described method for manufacturing a flexible electronic device, the heat conductive substrate has a multilayer structure composed of two or more layers of polyimide resin, and at least one layer is a heat conductive layer containing a heat conductive filler, and a device layer The layer on the contact side is preferably a smooth layer having a smooth surface.

Another aspect of the present invention is a flexible electronic device in which a metal support, a heat conductive resin substrate made of a polyimide resin containing a heat conductive filler in a range of 30 to 80 wt%, and a device layer are laminated in this order. Is a device.

It is preferable that the heat conductivity λxy in the plane direction of the heat conductive resin substrate is 0.7 W/mK or more, and the heat conductivity λz in the thickness direction is 0.3 W/mK or more.
The heat conductive resin substrate preferably contains the polyimide resin represented by the above formula (1).
It is preferable that a difference in thermal expansion coefficient between the metal support and the thermally conductive resin substrate is 15 ppm/K or less, and a difference in thermal expansion coefficient between the thermally conductive resin substrate and the device layer is 15 ppm/K or less.

The heat conductive substrate of the present invention is excellent in heat dissipation, low thermal expansion, high heat resistance and high toughness, and is suitable as a substrate for a display device or a light receiving device. In particular, it can be used as a substrate of an organic light emitting element including an organic EL lighting and an organic EL television. Also, instead of using a film that has already been molded as a film and has a fixed thickness, a resin solution suitable for device manufacturing is used. Can be applied. At this time, since the thickness of the resin layer can be adjusted to an optimum thickness by changing the coating film thickness, the flexible electronic device can be thinned.

Further, a thin film can be formed into a desired thin film by thinly applying a resin on a support such as a glass substrate, and a circuit, a display layer and the like can be formed thereon. Since it is a thin film with excellent toughness and a low coefficient of thermal expansion, it does not cause peeling or defects from the heat conductive substrate or the support in the process of forming a circuit or the like, and when peeling it from the support after that, The thermally conductive substrate itself and the circuits formed on it can be removed cleanly without causing any defects. Therefore, a method for manufacturing a flexible electronic device which is a display device or a light receiving device using the same is complicated because a circuit can be directly formed on a heat conductive substrate formed on a support and then peeled off. Different manufacturing steps can be omitted. Further, the obtained flexible electronic device has high toughness and excellent heat resistance even if it is thin.

Hereinafter, the method for manufacturing the flexible electronic device of the present invention will be described in detail.

The present invention, a step of applying a heat conductive resin material consisting of a resin and a filler to a support to produce a laminate composed of a heat conductive substrate and a support, a step of forming a device layer on the heat conductive substrate, And a method for manufacturing a heat conductive flexible electronic device including a step of separating the support and the heat conductive substrate.

According to this method, for example, a mixed solution of a polyamic acid (formal name; polyamic acid; the same applies below), which is a precursor of a polyimide resin, and a filler is directly applied on an appropriate support, dried and cured. Can be formed by the so-called casting method. Therefore, the device can be formed directly on the heat conductive substrate made of resin and filler, and the step of attaching the heat dissipation layer such as metal can be omitted. After forming the device, the flexible substrate can be obtained by peeling the heat conductive substrate from the support. Further, this method has an advantage that an existing production apparatus using a glass substrate can be used as it is, can be effectively used in the field of electronic devices such as flat panel displays and electronic paper, and is also suitable for mass production. As a method of peeling from the support, a known method can be used. For example, it may be peeled off by a person, or may be peeled off using a mechanical device such as a drive roll or a robot. Furthermore, the method of providing a peeling layer between a support body and a heat conductive substrate, and the method of separating with a laser beam can be mentioned. The removal from the support can be carried out by the above-mentioned known method, but it is preferably carried out by a mechanical method. In the following, an example of forming a polyimide resin layer using polyamic acid that is a precursor of a polyimide resin as the heat conductive resin material will be described, but the present invention is not limited to this.

Further, it can be used as one body without being removed from the support. In this case, the support which is in contact with the heat conductive substrate is a metal layer, so that the heat conductivity and heat dissipation can be improved. The metal species is not particularly limited, but aluminum, copper or an alloy containing them as a main component is preferable.

The application of the polyamic acid solution can be carried out by a known method, for example, a bar code method, a gravure coating method, a roll coating method, a die coating method or the like can be appropriately selected and employed.

The support used in the present invention is not particularly limited as long as it has supportability and resistance to a high temperature process, but a glass substrate is preferable in terms of handling property and transparency.

In the method of manufacturing a flexible electronic device of the present invention, the thermal conductivity of the thermally conductive substrate is such that the thermal conductivity λxy in the plane direction is 0.7 W/mK or more and the thermal conductivity λz in the thickness direction is 0.3 W/mK or more. It is more preferable that the thermal conductivity λxy in the plane direction is 1.0 W/mK or more, and the thermal conductivity λz in the thickness direction is 0.4 W/mK or more. If the thermal conductivity λxy in the plane direction is less than 0.7 W/mK, the heat cannot be sufficiently diffused, and if the thermal conductivity λz in the thickness direction is less than 0.3 W/mK, the heat generated in the device layer. Cannot be transmitted, and as a result, sufficient cooling efficiency cannot be obtained.

The filler in the heat conductive resin material is preferably a filler having heat conductivity, and the content ratio of the heat conductive filler in the heat conductive resin material is preferably in the range of 30 to 80 wt %, 40 to 40 The range of 70 wt% is preferable. If the content ratio of the filler in the heat conductive resin material is less than 30 wt %, the heat dissipation characteristics when used as an electronic member such as an organic light emitting element substrate becomes insufficient. If it exceeds 80 wt %, the flexibility (flexibility), which is a feature of the present invention, may be significantly reduced, and the strength of the polyimide resin layer may be reduced, and adjacent members such as an organic light emitting element and a barrier layer are laminated. It may be damaged or curled.

The heat conductive substrate preferably has good releasability from the support, and the peel strength can be adjusted by the content ratio of the filler. Peelability can be expressed by the strength of peel strength. As described above, the content ratio of the thermally conductive filler is preferably in the range of 30 to 80 wt%, and more preferably 40 to 70 wt%. If the content ratio of the filler in the heat conductive resin material is less than 30 wt %, the peel strength is improved and peeling becomes difficult. If the peeling is difficult, the adjacent device members (device layers) such as the organic light emitting element and the barrier layer may be damaged. On the other hand, if it exceeds 80 wt %, the peel strength is excessively lowered, and there is a risk that peeling may occur during manufacture, or wrinkles or deviations may occur.

In the present invention, for example, an organic light emitting device can be mentioned as an electronic device, but it is common to provide a gas barrier layer on at least one surface of the heat conductive substrate in order to prevent entry of moisture and oxygen into the organic light emitting element layer. .. Here, as the gas barrier layer having a barrier property against oxygen, water vapor, and the like, inorganic oxide films such as silicon oxide, aluminum oxide, silicon carbide, silicon oxycarbide, silicon carbonitride, silicon nitride, and silicon nitride oxide are preferably exemplified. To be done. Suitable examples of the support include glass and silicon materials, and metal materials such as copper and aluminum. If the difference in the coefficient of thermal expansion between the support and the thermally conductive substrate and the difference in the coefficient of thermal expansion between the inorganic oxide gas barrier layer and the thermally conductive substrate are large, curling occurs during the subsequent TFT manufacturing process. It may occur, the dimensional stability may be deteriorated, or cracks may occur.

Further, in general, when a large-area film is manufactured, warpage becomes a problem, but if the thermally conductive substrate of the present invention has a small difference in thermal expansion coefficient from the gas barrier layer, the problem of such a problem is solved. To be done. In the method for manufacturing a flexible electronic device, the difference in thermal expansion coefficient between the support and the thermally conductive substrate is 15 ppm/K or less, and the difference in thermal expansion coefficient between the thermally conductive substrate and the device layer is 15 ppm/K or less. Preferably, the difference in thermal expansion coefficient between the support and the thermally conductive substrate is 10 ppm/K or less, and the difference in thermal expansion coefficient between the thermally conductive substrate and the device layer is 10 ppm/K or less.

Table 1 shows typical inorganic films forming the support and the gas barrier layer and their thermal expansion coefficients. Here, the coefficient of thermal expansion varies depending on the manufacturing method even if the composition is the same, so the values shown in Table 1 are guidelines. Further, the gas barrier layer may be formed of one kind of the above-mentioned inorganic film, or may be formed so as to include two or more kinds.

In the present invention, as the kind of the filler contained in the heat conductive resin material, specifically, aluminum, copper, nickel, silica, diamond, alumina, magnesia, beryllia, boron nitride, aluminum nitride, silicon nitride, silicon carbide And the like. Among these, at least one kind of filler selected from silica, alumina, aluminum nitride, boron nitride, silicon nitride and magnesia is preferable. The shape of the filler is not particularly limited, and may be plate-like, needle-like, or rod-like. It is also preferable to use a spherical filler and a plate-like filler in combination in order to increase the content of these heat-conductive fillers and to consider the balance with properties such as heat conductivity. When the smoothing layer described below has a thickness of 10 μm or less, or when the smoothing layer is not used, it is preferable to use a plate-like filler in order to make the surface of the thermally conductive substrate on which the device layer is formed smooth. Depending on the type of filler, it contains a small amount of metal impurities, and if the metal impurities are mixed in the manufacturing process of the organic light-emitting element device, there is a concern that defects will occur, so high-purity fillers Is preferably used.

The particle size of the heat conductive filler is preferably in the range of 0.01 to 25 μm and more preferably in the range of 1 to 8 μm from the viewpoint of uniformly dispersing the filler in the thickness direction of the heat conductive substrate. Is more preferable. If the average particle size of the filler is less than 0.01 μm, the thermal conductivity inside each filler becomes small, and as a result, not only the thermal conductivity of the thermally conductive substrate does not improve, but also particles easily aggregate. Therefore, it may be difficult to uniformly disperse. On the other hand, when it exceeds 25 μm, the filling rate of the heat conductive layer is lowered, and the heat conductive substrate tends to be brittle due to the filler interface. The average particle size referred to here is the cumulative curve of the volume fraction of the particle size when the total volume of the particles is 100% in the particle size distribution measured by the laser diffraction/scattering method (measuring device: Microtrack MT3300EX). It refers to the particle size when 50% is accumulated.

The most suitable spherical filler used in the present invention is a filler having an average particle diameter in the range of 0.5 to 3.0 μm, and it is preferable to use aluminum oxide or aluminum nitride. Further, the optimum plate-like filler used in the present invention has an average particle size of 0.1 to 15 μm, particularly preferably 0.5 to 8 μm. Boron nitride is preferably used as the plate-like filler. If the average particle size is less than 0.1 μm, the thermal conductivity will be low and the plate-like effect will be small. On the other hand, if it exceeds 15 μm, it becomes difficult to align it during film formation. The average particle size of the heat conductive filler also relates to the thickness of the polyimide resin layer. The average particle size of the heat conductive filler is 70% or less, preferably 50% or less of the thickness of the polyimide resin layer.

Further, in the present invention, the heat conductive substrate may have a multi-layer structure made of two or more layers of polyimide resin. In that case, at least one layer is a heat conductive layer containing a heat conductive filler, and the layer in contact with the device layer is preferably a smooth layer having a smooth surface. That is, when another smooth layer is provided on the surface of the heat conductive layer containing the resin and the heat conductive filler, the surface roughness (Ra) of the smooth layer is preferably 100 nm or less. If the roughness is higher than this, the unevenness may affect the light emitting element, resulting in deterioration of image quality. The smooth layer may be formed of resin alone, or may include a heat conductive filler. When the smooth layer contains a thermally conductive filler, it is preferable to use a nanofiller so that the formed surface becomes smooth. The surface roughness (Ra) of the surface of the heat conductive layer or the smooth layer in contact with the atmosphere was observed four times in a tapping mode using an atomic force microscope (AFM), and the field of view of 10 μm square was observed four times. It represents the arithmetic average roughness (JIS B0601-1991) for which the average value was obtained.

The average particle size of the nanofiller used for the smooth layer is preferably in the range of 200 nm or less, and more preferably in the range of 100 nm or less. If the average particle size of the nanofiller exceeds 200 nm, the surface becomes rough, which may reduce the smoothness. If the roughness is higher than this, the unevenness may affect the light emitting element, resulting in deterioration of image quality. However, the lower limit of the average particle size of the nanofiller is substantially 10 nm. The nanofiller is not particularly limited, but specific examples thereof include aluminum, copper, nickel, silica, diamond, alumina, magnesia, beryllia, boron nitride, aluminum nitride, silicon nitride, and silicon carbide. Among these, at least one nanofiller selected from silica, alumina, aluminum nitride, boron nitride, silicon nitride and magnesia is preferable. The shape of the filler is not particularly limited, and may be plate-like, needle-like, or rod-like. It is preferable to use surface-treated nanofillers. Regarding the average particle size of the nanofiller, in the particle size distribution measured by the laser diffraction/scattering method (measuring device: Microtrac MT3300EX) as in the case of the average particle size of the heat conductive filler, the total volume of the particles is 100%. In this case, it means the particle diameter at which 50% is accumulated in the cumulative curve of the volume fraction of the particle diameter.

When the smooth layer contains the nanofiller, it is preferably smaller than the content ratio of the heat conductive filler in the heat conductive layer. Moreover, the content ratio is preferably in the range of 1 to 50 wt %, and more preferably in the range of 10 to 40 wt %. When the content ratio of the nanofiller in the smooth layer exceeds 50 wt %, not only the adhesiveness to an adjacent member is deteriorated but also the strength of the smooth layer is reduced.

As described above, in the case of a multilayer structure, all layers constituting the heat conductive substrate may contain a filler, and if at least one layer is a layer containing a filler, a layer containing no filler is used. May be included. In that case, it is preferable that the thickest layer is a layer containing a filler. That is, in the above example, the thickness of the heat conductive layer is preferably 1 μm to 100 μm, and more preferably 5 μm to 50 μm. If it is smaller than this range, the irregularities due to the filler become large, and if it is larger than this range, the heat conduction efficiency may decrease. Further, the thickness of the smoothing layer is preferably 0.1 μm to 30 μm, and more preferably 2 μm to 5 μm. If it is smaller than this range, a sufficient smoothing effect cannot be obtained, and if it is larger than this range, thermal conductivity is hindered, which is not preferable.

Taking TFT formation as an example of manufacturing a flexible electronic device, the annealing process of the TFT generally requires a heat treatment temperature of about 300 to 400° C. Therefore, when a resin is used as the supporting substrate, the heat treatment of the TFT is performed. It must have heat resistance and dimensional stability at temperature. On the other hand, although there is a case where a TFT is not required as in an organic EL device for lighting, the resistance value of the transparent electrode is lowered by increasing the film forming temperature of the transparent electrode adjacent to the supporting base material. Since the power consumption can be reduced, it is the same that the supporting base material is required to have heat resistance even in the case of lighting applications. Therefore, the resin used in the present invention preferably has a glass transition temperature of 280°C or higher, and more preferably 350°C or higher.

When forming a transparent electrode as another example, metal oxides such as ITO are generally used as the transparent electrode, and they have a coefficient of thermal expansion of 0 to 10 ppm/K, so cracks and peeling are caused. In order to avoid the above problem, a resin having a similar coefficient of thermal expansion is required. The thermal expansion coefficient of the resin is preferably 60 ppm/K or less, more preferably 15 ppm/K or less.

The resin used for the heat conductive substrate is not limited, but a polyimide resin is preferable from the viewpoint of reducing the coefficient of thermal expansion. The polyimide resin preferably has a linear structure, and the linear structure is preferable because the thermal conductivity in the plane direction is higher than the thermal conductivity in the longitudinal direction. The polyimide resin structure represented by the following general formula (1) is more preferable. It is preferable to contain the structural unit represented by the general formula (1) in an amount of 10 to 95 mol %, preferably 50 to 95 mol %. That is, by blending a certain amount or more of the structural unit represented by the following general formula (1), the coefficient of linear expansion can be reduced, the thermal conductivity in the plane direction can be increased, and a heat diffusion effect can be expected.

In the general formula (1), Ar1 is a tetravalent organic group having one or more aromatic rings, R is a lower alkyl group having 1 to 6 carbon atoms, a lower alkoxy group having 1 to 6 carbon atoms, a phenyl group, a phenoxy group. A group or halogen. Since Ar1 can be regarded as a residue of an aromatic tetracarboxylic acid that is a raw material for polyimide, Ar1 is understood by showing a specific example of the aromatic tetracarboxylic acid. Further, R can be regarded as a part of the residue of the aromatic diamine which is the raw material for polyimide.

Specific examples of the aromatic tetracarboxylic acid, pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,2',3,3'-benzophenone Tetracarboxylic acid dianhydride, 2,3,3',4'-benzophenone tetracarboxylic acid dianhydride, naphthalene-2,3,6,7-tetracarboxylic acid dianhydride (NTCDA), naphthalene-1,2 ,5,6-Tetracarboxylic acid dianhydride, naphthalene-1,2,4,5-tetracarboxylic acid dianhydride, naphthalene-1,4,5,8-tetracarboxylic acid dianhydride, naphthalene-1, 2,6,7-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 4,8-Dimethyl-1,2,3,5,6,7-hexahydronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5, 8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8 -Tetracarboxylic acid dianhydride, 1,4,5,8-Tetrachloronaphthalene-2,3,6,7-tetracarboxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride Anhydride (BPDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3'',4, 4''-p-terphenyltetracarboxylic dianhydride, 2,2'',3,3''-p-terphenyltetracarboxylic dianhydride, 2,3,3'',4''- p-terphenyl tetracarboxylic dianhydride, 2,2-bis(2,3-dicarboxyphenyl)-propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-propane dianhydride , Bis(2,3-dicarboxyphenyl)ether dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3.4-dicarboxyphenyl)methane dianhydride, bis(2,3- Dicarboxyphenyl) sulfone dianhydride, bis(3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3 ,4-Dicarboxyphenyl)ethane dianhydride, perylene-2,3,8,9-tetracarboxylic dianhydride Perylene-3,4,9,10-tetracarboxylic dianhydride, perylene-4,5,10,11-tetracarboxylic dianhydride, perylene-5,6,11,12-tetracarboxylic dianhydride Anhydride, phenanthrene-1,2,7,8-tetracarboxylic dianhydride, phenanthrene-1,2,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-tetracarboxylic acid Dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetra Examples thereof include carboxylic acid dianhydride, thiophene-2,3,4,5-tetracarboxylic acid dianhydride, and 4,4′-oxydiphthalic acid dianhydride.

As the structural units other than the structural unit represented by the general formula (1), the aromatic tetracarboxylic acid residue and the aromatic diamine residue, which are polyimide raw materials, will be described separately. Examples of the residue include the same aromatic tetracarboxylic acid residues as described for Ar1 above.

Examples of the aromatic diamine residue include the following aromatic diamine residues. For example, 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-diaminomesitylene, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2. ,6-Xylidine, 4,4'-methylene-2,6-diethylaniline, 2,4-toluenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane, 3,3'- Diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 2,2-bis[4-(4-amino Phenoxy)phenyl]propane 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 3 ,3-Diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, benzidine, 3,3 '-Diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4'-diamino-p-terphenyl, 3,3'-diamino-p-ter Phenyl, bis(p-aminocyclohexyl)methane, bis(p-β-amino-t-butylphenyl) ether, bis(p-β-methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4) -Aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis(β-amino-t-butyl) ) Toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2 ,5-Diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,7-diaminodibenzofuran, 1,5- Diaminofluorene, dibenzo-p-dioxin-2,7-diamine, 4,4′-diaminobenzyl and the like can be mentioned.

When synthesizing the polyimide resin that constitutes the heat-conducting layer, the diamine and the acid anhydride may be used alone or in combination of two or more, but at least one of the diamine and the acid anhydride is used. Uses two or more. Advantageously, diamines such as 2,2'-dimethyl-4,4'-diaminobiphenyl which give the structural unit represented by the general formula (1) are used, and other diamines represented by the general formula (1) are used. It is preferable to use in combination with another diamine which gives a structural unit which is not formed.

In the present invention, since the heat conductive layer contains a heat conductive filler, it is necessary to maintain the mechanical strength of the polyimide resin while maintaining excellent heat resistance and dimensional stability. From such a viewpoint, as the other diamine, an aromatic diamine having a structure less rigid than the diamine providing the structural unit represented by the general formula (1) is suitable. Advantageously, the diamine component contains 2,2'-dimethyl-4,4'-diaminobiphenyl as a main component, to which 1,3-bis(3-aminophenoxy)benzene and 1,3-bis(4-amino) are added. At least one diamine selected from phenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 3,4'-diaminodiphenyl ether and 4,4'-diaminodiphenyl ether is used as another diamine, It is preferable to use pyromellitic dianhydride as the main component in the anhydride. The proportion of the other diamine used is preferably in the range of 5 to 50 mol %.

Since the polyimide having the structural unit represented by the general formula (1) has an elastic modulus of about 5 GPa to 10 GPa and is relatively hard, a polyimide layer (smooth layer) having a lower elastic modulus than that is used as a device. It may be arranged so as to be in contact with the layer so as to play a role of stress relaxation.

The polyimide resin forming the smooth layer preferably has a lower glass transition temperature (Tg) than the polyimide resin forming the heat conducting layer, but is a layer of thermoplastic polyimide resin having a Tg of 200° C. or higher. Is preferred. More preferably, it is a thermoplastic resin having a Tg in the range of 200 to 350° C., and a layer having a Tg of 20° C. or more lower than that of the polyimide resin constituting the heat conductive layer. On the other hand, since the heat conductive layer becomes a base layer having a thickness of 50% or more of that of the heat conductive substrate, it also preferably has a high Tg, preferably 310°C or higher, and in the range of 350 to 450°C. More preferable. As the polyimide resin forming the smooth layer, a known polyimide resin can be used as long as it satisfies the above physical properties, and can be obtained from the above-mentioned acid dianhydride component and diamine component.

Here, as the acid dianhydride component used for producing the smooth layer, pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) ,3,3',4,4'-Benzophenone tetracarboxylic acid dianhydride (BTDA), 3,3',4,4'-Diphenylsulfone tetracarboxylic acid dianhydride (DSDA), 4,4'-oxydiphthalate An aromatic acid dianhydride such as acid dianhydride (ODPA) is exemplified. In addition, as the diamine component, 2,2-bis(4-aminophenoxyphenyl)propane (BAPP), bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), 3,4′-diaminodiphenyl ether (3 ,4'-DAPE), 4,4'-diaminodiphenyl ether (4,4'-DAPE), 1,4-bis(4-aminophenoxy)benzene (TPE-Q), 4,4'-bis(4- Aminophenoxy)biphenyl (BAPB), 1,3-bis(3-aminophenoxy)benzene (APB), 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(4- Aromatic diamines such as aminophenoxy)-2,2-dimethylpropane (DANPG) are exemplified as preferred.

Since the smoothing layer is provided mainly for providing the substrate with smoothness, it is preferable that the thickness thereof be thin. As described above, it depends on the size of the heat conductive substrate and the heat generation amount of the light emitting element. As a guide, it is preferably 30 μm or less, more preferably 5 μm or less. If the thickness is larger than this, the thermal conductivity may decrease.

At least when forming a heat conductive layer, the polyamic acid solution containing the heat conductive filler, for example, a certain amount of the heat conductive filler to the polyamic acid solution containing the solvent obtained by prepolymerization, stirring device And a diamine and an acid anhydride are added to the solvent while the thermally conductive filler is dispersed in a solvent, and polymerization is performed. Either method may be used, when a high viscosity polyamic acid is used, it is preferable to mix a heat conductive filler in a solvent in advance before polymerization, and when a low viscosity polyamic acid is used after polymerization, polyamic acid is used. It is preferable to mix a thermally conductive filler in the acid solution.

The polyamic acid can be produced by a known method of using an aromatic diamine component and an aromatic tetracarboxylic acid dianhydride component in substantially equimolar amounts and polymerizing in a solvent. That is, it can be obtained by dissolving the above diamine in a solvent such as N,N-dimethylacetamide under a nitrogen stream, adding aromatic tetracarboxylic dianhydride, and reacting at room temperature for about 3 hours. A preferable degree of polymerization of the polyamic acid suitable for forming the heat conductive layer and the smooth layer is, when expressed in the viscosity range, a solution viscosity in the range of 5 to 2,000 P from the viewpoint of easy handling and flattening ability. , 10 to 300P is more preferable. The solution viscosity can be measured with a cone-plate type viscometer equipped with a constant temperature water tank. Examples of the solvent include N,N-dimethylacetamide, n-methylpyrrolidinone, 2-butanone, diglyme, xylene and the like, and these may be used alone or in combination of two or more.

The heat conductive substrate in the present invention is preferably used as a substrate for an organic light emitting device, that is, a flat panel display, a backlight for a liquid crystal display, or a light source for illumination, and more preferably, a top emission type organic light emitting device. It is preferable to use it as a substrate. In the top emission type, since there is no member that contributes to heat dissipation on the light emitting element side, heat is easily stored, and therefore it is preferable to use a substrate having high thermal conductivity. Further, the heat conductive substrate is a member constituting the organic light emitting device, and any one or more of a thin film transistor, an electrode layer, an organic EL light emitting layer, electronic ink, a color filter is formed on the heat conductive substrate. Preferably. The organic light emitting device in the present invention means a device made of an organic substance that emits light by itself, and examples thereof include an organic electroluminescence device. The structure of the organic electroluminescence element is composed of a layer having necessary functions such as a light emitting layer, an electrode and an electron injecting layer, and a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode. An element that emits light by injecting electrons and holes into and recombining to generate excitons (excitons), and using the emission of light (fluorescence/phosphorescence) when the excitons are deactivated. is there.

Hereinafter, the content of the present invention will be specifically described based on Examples, but the present invention is not limited to the scope of these Examples.

The abbreviations used in this example indicate the following compounds.
m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl 4,4'-DAPE: 4,4'-diaminodiphenyl ether TPE-R: 1,3-bis(4-aminophenoxy)benzene BAPP: 2,2-bis(4-aminophenoxyphenyl)propane PMDA: pyromellitic dianhydride BPDA: 3,3′4,4′-biphenyltetracarboxylic acid ODPA: 4,4′-oxydiphthalic acid dianhydride DMAc: N,N-dimethylacetamide

Moreover, the following evaluation methods were applied to the respective properties evaluated in the examples.

[Measurement of viscosity]
The viscosity of the polyamic acid solution was measured at 25° C. with a cone plate type viscometer (manufactured by Tokimec Co.) equipped with a constant temperature water tank.

[Thickness direction thermal conductivity (λzTC)]
The polyimide resin film was cut into a size of 30 mm × 30 mm, and the thermal diffusivity in the thickness direction by the periodic heating method (FTC-1 device manufactured by ULVAC-RIKO), the specific heat by DSC, and the density by the underwater substitution method were measured, respectively, and these results are shown. The thermal conductivity (W/m·K) was calculated based on the above.

[Plane thermal conductivity (λxyTC)]
The polyimide resin film was cut into a size of 30 mm × 30 mm, and the thermal diffusivity in the surface direction by the optical alternating current method (LaserPIT device manufactured by ULVAC-RIKO), the specific heat by DSC, and the density by the water displacement method were measured, respectively, and the results were used as the basis. The thermal conductivity (W/m·K) was calculated.

[Coefficient of thermal expansion (CTE)]
A tensile test is performed on a polyimide resin film having a size of 3 mm×15 mm in a temperature range of 30° C. to 260° C. at a constant heating rate (20° C./min) while applying a load of 5 g with a thermomechanical analysis (TMA) device. The thermal expansion coefficient (ppm/K) was measured from the elongation amount of the polyimide film with respect to temperature.

[Glass transition temperature (Tg)]
When the temperature of the polyimide resin film (10 mm x 22.6 mm) was raised from 20°C to 500°C at 5°C/min with a dynamic thermomechanical analyzer (formal name; dynamic viscoelasticity measuring device (DMA)) The dynamic viscoelasticity was measured to determine the glass transition temperature (tan δ maximum value: °C).

[180 degree peel strength]
The copper foil layer of the laminate was pattern-etched into a rectangular shape having a width of 1.0 mm and a length of 180 mm, and a test piece was cut out to have a width of 20 mm and a length of 200 mm so that the pattern was at the center, and IPC-TM-650. A 180° peeling test was conducted according to 2.4.19.

Synthesis Examples 1 to 4
In order to synthesize the polyamic acid solution A, m-TB (32 g, 0.90 mol) and TPE-R (4.8 g, 0.10 mol) were stirred under a nitrogen stream in a 1000 ml separable flask while stirring. It was dissolved in 425 g of DMAc. Then BPDA (9.7 g, 0.197 mol), PMDA (28.5 g, 0.788 mol) were added. Then, the solution was continuously stirred at room temperature for 3 hours to carry out a polymerization reaction to obtain a dark brown viscous polyamic acid solution A. Hereinafter, based on the composition shown in Table 2, polyamic acid solutions B to D were synthesized by the same method as above. Polyamic acid solutions A to D consisted of polyamic acid and the solvent DMAc, and the viscosity, thermal expansion coefficient, and glass transition temperature of the polyamic acid solution were measured.

Synthesis Examples 5-18
Next, 43.5 parts by weight of the polyamic acid solution A having a solid content concentration of 15 wt%, 3.25 parts by weight of aluminum oxide [spherical, average particle size 3 μm], and boron nitride [plate-shaped, average particle size 4. 5 μm] was mixed with 3.25 parts by weight with a centrifugal stirrer until it became uniform to obtain a mixed solution of polyamic acid containing a thermally conductive filler and a filler (Sample E).

Hereinafter, based on the compositions shown in Tables 3 and 4, the remaining samples F to R were synthesized by the same method as described above. At this time, the solid content concentration in the polyamic acid solution B was 15 wt %, and the solid content concentration in the polyamic acid solutions C and D was 12 wt %. Further, when using the polyamic acid solutions A and B (Samples E5 to 15), 20% (8.72 parts by weight) of DMAc was added to the polyamide resin solution for viscosity adjustment, and the mixture was centrifugally stirred until uniform. Mixed in. The numerical values of diamine, tetracarboxylic dianhydride, polyamic acid solution and filler in Tables 2 to 4 represent parts by weight of each component.

Samples E to R are mixed solutions obtained by mixing the polyamic acid solutions A to D in Table 2 and the thermally conductive filler based on the formulation table in Table 3. As the heat conductive filler, Al2O3 is a spherical filler having an average particle diameter of 3 μm and 0.6 μm, BN is a plate-like filler having an average particle diameter of 4.5 μm and 2.3 μm, and AlN is a spherical filler having an average particle diameter of 1.1 μm. Using. The average particle diameter here is a cumulative curve of the volume fraction of the particle diameter when the total volume of the particles is 100% in the particle diameter distribution measured by the laser diffraction/scattering method (measuring device: Microtrack MT3300EX). Represents the particle size when 50% is accumulated.

Film Preparation Example and Reference Example The polyamic acid resin solution C obtained in Synthesis Example 3 was applied on a glass substrate so that the thickness after curing was about 2 μm, and dried by heating at 120° C. to remove the solvent. Next, the solution of the polyamic acid resin E obtained in Synthesis Example 5 was applied thereon so that the thickness after curing would be about 21 μm, and dried by heating at 120° C. to remove the solvent. Further, the polyamic acid resin solution C obtained in Synthesis Example 3 was applied thereon so that the thickness after curing would be about 2 μm, and dried by heating at 120° C. to remove the solvent. Then, in a temperature range of 120 to 360[deg.] C., the temperature is raised stepwise over 30 minutes to heat, and a heat conductive substrate laminate composed of three polyimide resin layers (C/E/C) is formed on the glass. It was made. In order to evaluate the properties of the polyimide resin layer, the polyimide resin layer was peeled from the glass substrate to prepare a polyimide resin film (M1). The CTE and thermal conductivity of this polyimide resin film were evaluated. In the same manner, three-layer, two-layer and single-layer polyimide resin films M2 to M14 and M16 to M21 were formed on the glass substrate in the same manner, and then CTE and thermal conductivity were evaluated. The results are shown in Table 5.

Here, M1 to M6 in Table 5 are laminate films of a film made of a polyimide resin, a thermally conductive filler, and a film made of the polyimide resin. M7 to M14 are single-layer films made of a polyimide resin and a heat conductive filler. M15 is a reference example for comparison of physical properties, and is a heat conductive polyimide resin film (Kapton (registered trademark) MT: thickness 43 μm) manufactured by DuPont. M16 to M17 are laminates composed of polyimide resin films having different compositions. M18 to M21 are single-layer films made of polyimide resins having different compositions. The layer structure and thickness structure of the film are as shown in Table 5. For M1 to M21, the coefficient of thermal expansion, the thermal conductivity in the longitudinal direction and the thermal conductivity in the lateral direction, and the surface roughness were measured. The thermal expansion coefficient of M3 could not be measured due to insufficient mechanical strength.

Examples 1-2
A resin composition (Q) consisting of polyamic acid solution D and AlN (71 wt%) was applied onto a 20 μm copper foil and imidized to obtain a laminated film (M22) having a thickness of 5 μm. Table 6 shows the peel strength of the obtained laminate film with the copper foil. A laminated film in which a TFT is formed by sequentially forming a SiN layer (150 μm) and a SiO layer (100 μm) as a gas barrier on this laminated film by a known method, and then forming an amorphous silicon layer 50 μm to be a TFT. After that, the thermally conductive substrate on which the TFT was formed was peeled from the copper foil to obtain a flexible electronic device. There was no significant change in peel strength even after the TFT was formed. Similarly, when a resin film composed of polyamic acid solution D and AlN (51 wt%) was applied on a copper foil to form an imidized laminate film (M23) and a TFT was formed, the same flexible electronic device was obtained. Got

Comparative Examples 1 and 2
A laminate film (M24, M25) of a polyimide resin layer containing no heat conductive filler and a copper foil was prepared with the layer constitution shown in Table 2. After measuring the 180-degree peel strength, a TFT was formed in the same manner as in Examples 1 and 2, but it could be physically peeled from the copper foil, but a crack occurred in the TFT.

Regarding the above Examples and Comparative Examples, the films (M22/23) used in Examples 1 and 2 were different from the films (M24/25) used in Comparative Examples 1 and 2 depending on the presence or absence of the heat conductive filler in the resin layer. Since it has different peeling properties from the support, and the layer composed of the resin and the thermally conductive filler has better peelability from the base material than the layer of the resin alone, it is an optimum material for the display device. is there.

In addition, not only the thermal conductivity increased due to the presence or absence of the thermally conductive filler in the resin layer, but also the amount and type of the thermally conductive filler was optimized to dramatically improve the lateral thermal conductivity. I was able to raise it. That is, compared to the difference in the thermal conductivity in the vertical direction and the horizontal direction in the comparative example, the difference in the thermal conductivity in the same direction in the example is large, so that the accumulated heat, which was a cause of burn-in and afterimage, can be quickly Can spread.

Claims (10)

A process of applying a heat conductive resin material containing 30 to 80 wt% of a heat conductive filler to a polyimide resin to a metal support to produce a laminate substrate including the heat conductive resin substrate and the metal support, and a laminate A method of manufacturing a flexible electronic device, comprising the step of forming a device layer on a heat conductive resin substrate of the substrate. The thermal conductivity λxy in the plane direction of the thermally conductive resin substrate is 0.7 W/mK or more, and the thermal conductivity λz in the thickness direction is 0.3 W/mK or more. Flexible electronic device manufacturing method. The method for manufacturing a flexible electronic device according to claim 1, wherein the thermally conductive resin substrate contains a polyimide resin represented by the following formula (1).

In the formula (1), Ar ₁ is a tetravalent organic group having at least one aromatic ring, R is a lower alkyl group having 1 to 6 carbon atoms, a lower alkoxy group having 1 to 6 carbon atoms, a phenyl group, a phenoxy group. A group or halogen. The thermal expansion coefficient difference between the metal support and the thermally conductive resin substrate is 15 ppm/K or less, and the thermal expansion coefficient difference between the thermally conductive resin substrate and the device layer is 15 ppm/K or less. A method of manufacturing a flexible electronic device according to. The heat conductive resin substrate has a multi-layer structure composed of two or more layers of polyimide resin, at least one layer is a heat conductive layer containing a heat conductive filler, and the layer in contact with the device layer has a smooth surface. It is a smooth layer, The manufacturing method of the flexible electronic device in any one of Claims 1-4. The method for manufacturing a flexible electronic device according to claim 1, wherein the flexible electronic device is a display device or a light emitting device. A flexible electronic device in which a metal support, a heat conductive resin substrate made of a polyimide resin containing a heat conductive filler in a range of 30 to 80 wt%, and a device layer are laminated in this order. The flexible electronic device according to claim 7, wherein the heat conductivity λxy in the plane direction of the heat conductive resin substrate is 0.7 W/mK or more, and the heat conductivity λz in the thickness direction is 0.3 W/mK or more. 9. The flexible electronic device according to claim 7, wherein the thermally conductive resin substrate contains the polyimide resin represented by the formula (1).

In the formula (1), Ar ₁ is a tetravalent organic group having at least one aromatic ring, R is a lower alkyl group having 1 to 6 carbon atoms, a lower alkoxy group having 1 to 6 carbon atoms, a phenyl group, a phenoxy group. A group or halogen. The thermal expansion coefficient difference between the metal support and the thermally conductive resin substrate is 15 ppm/K or less, and the thermal expansion coefficient difference between the thermally conductive resin substrate and the device layer is 15 ppm/K or less. 9. The flexible electronic device according to any of 9.