High-temperature film type electric heating sheet and preparation method and application thereof

Abstract

The invention belongs to the technical field of heating components, and relates to a high-temperature film type electric heating sheet and a preparation method and application thereof.The high-temperature film type electric heating sheet comprises a base material layer, a conductor layer, a heating layer and an insulation packaging layer which are sequentially arranged, and the base material layer and the insulation packaging layer are made of polyimide independently. The conductor layer is made of conductive silver paste and / or etched copper foil, and the heating layer is made of polymer resistance paste; and the working temperature of the high-temperature film type electric heating sheet is greater than or equal to 200 DEG C. According to the high-temperature film type electric heating sheet provided by the invention, by optimizing and improving the materials of each layer, efficient heating and the working temperature of 200 DEG C or above are realized, the manufacturing cost is reduced while the heating efficiency is improved, and the manufacturing and lightweight design of curved-surface or heterogeneous elements is realized by the film type structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of heating components and relates to an electric heating sheet, in particular to a high-temperature thin-film electric heating sheet and a preparation method and application thereof. Background Art

[0002] Electric heater is a device that converts electrical energy into thermal energy. It is widely used in many fields. Common electric heaters include PTC (positive temperature coefficient) ceramic heaters and thick film heaters.

[0003] Among them, the working principle of PTC ceramic heater is based on the characteristic that the resistance of PTC ceramic material changes with temperature, thereby achieving constant temperature heating. This characteristic enables PTC heater to have a good self-limiting temperature function in low temperature environment to avoid overheating. Thick film heater is an electric heater formed by sintering thick film slurry (such as resistor slurry, conductor slurry, etc.) on stainless steel, aluminum, ceramic and other substrates through screen printing technology to form a heating element. It has the characteristics of rapid heating, uniform heat dissipation and low power consumption.

[0004] For example, CN209767838U discloses a metal PTC electric heater, including a frame, a PTC element, and a lead-out electrode that is externally attached to the PTC element and led out through a power cord. The PTC element and the lead-out electrode are wrapped with an insulating film and then pressed into a square tube to form an electric heater body. The electric heater body is placed in the frame, and a temperature sensor for sensing the temperature emitted by the electric heater body is provided on the frame. A fan is provided on one side of the frame, and the fan is electrically connected to a single-chip microcomputer for controlling the fan to be turned off. The single-chip microcomputer is electrically connected to the temperature sensor, which has the effect of improving the performance and service life of the PTC electric heater.

[0005] However, the PTC elements of the above-mentioned PTC electric heater need to be assembled one by one, with high labor costs and low production efficiency. Its heating efficiency is significantly affected by the ambient temperature. In a high temperature environment, the heating power of the PTC electric heater will be reduced, resulting in slower heating speed or unstable temperature control. At the same time, there are problems of high cost and limited scope of application.

[0006] For another example, CN211090000U discloses a thick film heater with fins, including a substrate and a screen-printed layer, the screen-printed layer is arranged on one side of the substrate, and the fins are arranged on the other side of the substrate. This arrangement can quickly transfer the generated heat after the substrate is heated, thereby reducing the temperature of the thick film heater. The cross-section of the fin is wavy, which increases the contact area between the fin and the air and improves the heat dissipation efficiency; at the same time, the fin material is aluminum alloy, the substrate is stainless steel, and a solder composite layer is arranged between the fin and the substrate, so that the fin and the substrate can be welded together.

[0007] However, the manufacturing process of the thick film heater is relatively complicated, requiring sophisticated microelectronic processing technology, and the raw materials are relatively expensive. Because it uses a stainless steel substrate, the heat cannot be evenly distributed during the heat conduction process, resulting in local high temperature, which in turn affects the service life of the heater. It is also impossible to manufacture curved or heterogeneous components, and it is relatively thick and heavy, making it difficult to achieve lightweight.

[0008] It can be seen that, given the many defects of the existing PTC ceramic heaters and thick film heaters, how to improve the electric heaters, improve the heating efficiency while reducing the manufacturing cost, and realize the manufacturing and lightweight design of curved or heterogeneous components has become an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0009] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a high-temperature thin-film electric heating plate and a preparation method and application thereof. By optimizing and improving the materials of each layer in the thin-film electric heating plate, efficient heat generation and an operating temperature above 200°C are achieved, thereby improving the heating efficiency and reducing the manufacturing cost. The thin-film structure realizes the manufacturing and lightweight design of curved or heterogeneous components.

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a high-temperature thin-film electric heating plate, comprising a substrate layer, a conductor layer, a heating layer and an insulating packaging layer arranged in sequence, wherein the materials of the substrate layer and the insulating packaging layer independently include polyimide, the material of the conductor layer includes conductive silver paste and / or etched copper foil, and the material of the heating layer includes polymer resistor paste.

[0011] The working temperature of the high temperature thin film type electric heating plate is ≥200°C.

[0012] The high-temperature thin-film electric heating plate provided by the present invention achieves efficient heating and an operating temperature of more than 200°C by optimizing and improving the materials of the substrate layer, the conductor layer, the heating layer and the insulating packaging layer. It has high heat transfer efficiency, low thermal resistance and low resistance temperature coefficient, which improves the heating efficiency while reducing the manufacturing cost. The thin-film structure realizes the manufacturing and lightweight design of curved or heterogeneous components, which enables terminal heater manufacturers to perform simplified processing and save labor costs.

[0013] Preferably, the substrate layer is a polyimide film.

[0014] Preferably, the polyimide film comprises a homophenyl polyimide film or a biphenyl polyimide film.

[0015] Preferably, the polyimide film has a thickness of 5-125 μm.

[0016] Preferably, the conductive silver paste is a high temperature curing conductive silver paste.

[0017] Preferably, the sheet resistance of the high temperature curing conductive silver paste is 1-1000 mΩ.

[0018] Preferably, the etched copper foil has a thickness of 2-72 μm.

[0019] Preferably, the polymer resistor paste consists of a carrier phase and a conductive phase.

[0020] Preferably, the carrier phase is a polymer resin solution.

[0021] Preferably, the polymer resin in the polymer resin solution includes any one of polyimide resin, polyetheretherketone resin or liquid crystal polymer resin, or a combination of at least two of them.

[0022] Preferably, the solvent in the polymer resin solution includes any one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or dimethoxybenzene, or a combination of at least two thereof.

[0023] Preferably, the conductive phase includes any one of graphite, carbon black, graphene or metal oxide, or a combination of at least two of them.

[0024] Preferably, the sheet resistance of the polymer resistor paste is 1-50000Ω / sq.

[0025] Optionally, the insulating packaging layer is a polyimide resin layer.

[0026] Optionally, the insulating packaging layer is a composite layer of a polyimide adhesive film and a polyimide film.

[0027] In a second aspect, the present invention provides a method for preparing the high-temperature thin-film electric heating sheet as described in the first aspect, the preparation method comprising the following steps: (1) A conductive silver paste and / or etched copper foil is provided on the surface of a polyimide substrate layer as a conductor layer; (2) The polymer resistor slurry is coated on the surface of the substrate layer and the conductor layer by a screen printing process or a precision coating process to form a heating layer, and an electrical connection is formed between the conductor layer and the heating layer; (3) The conductor layer and the heating layer are encapsulated by using an insulating encapsulation layer made of polyimide material to obtain a high-temperature thin-film electric heating sheet.

[0028] Preferably, in step (1), the conductive silver paste is coated on the surface of the substrate layer by a screen printing process or a precision coating process.

[0029] Preferably, the packaging process in step (3) includes any one of the following two methods: (3.1) coating the unimidized polyimide resin coating on the surface of the substrate layer and covering the conductor layer and the heating layer, and performing a drying treatment to achieve imidization of the polyimide resin coating to form a composite structure; (3.2) Covering the composite layer of the polyimide film and the polyimide thin film on the surface of the substrate layer, and the polyimide film covering the conductor layer and the heating layer, the polyimide film is subjected to lamination treatment to melt the polyimide film to produce bonding effect, thereby forming a composite structure.

[0030] Preferably, the coating method in step (3.1) includes any one of blade coating, slit coating or gravure coating.

[0031] Preferably, the temperature of the drying treatment in step (3.1) is ≥ 280°C.

[0032] Preferably, the applied pressure of the lamination process in step (3.2) is 0.1-2 MPa.

[0033] Preferably, the temperature of the lamination process in step (3.2) is 150-300°C.

[0034] Preferably, the lamination treatment time in step (3.2) is 1-60 min.

[0035] In a third aspect, the present invention provides an application of a high-temperature thin-film electric heating plate as described in the first aspect, and the application includes: the high-temperature thin-film electric heating plate leads out the circuit through terminal bonding or welding, forms an electrical connection with the power supply, and realizes the heating function.

[0036] Compared with the prior art, the present invention has the following beneficial effects: The high-temperature thin-film electric heating plate provided by the present invention achieves efficient heating and an operating temperature of more than 200°C by optimizing and improving the materials of the substrate layer, the conductor layer, the heating layer and the insulating packaging layer. It has high heat transfer efficiency, low thermal resistance and low resistance temperature coefficient, which improves the heating efficiency while reducing the manufacturing cost. The thin-film structure realizes the manufacturing and lightweight design of curved or heterogeneous components, which enables terminal heater manufacturers to perform simplified processing and save labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The present invention provides a flow chart of a method for preparing a high-temperature thin-film electric heating sheet.

[0038] Among them: 10 - substrate layer; 20 - conductor layer; 30 - heating layer; 40 - insulating packaging layer; 41 - polyimide adhesive film; 42 - polyimide film. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0040] A certain embodiment of the present invention provides a high-temperature thin-film electric heating plate, comprising a substrate layer, a conductor layer, a heating layer and an insulating packaging layer arranged in sequence, wherein the materials of the substrate layer and the insulating packaging layer independently include polyimide, the material of the conductor layer includes conductive silver paste and / or etched copper foil, and the material of the heating layer includes polymer resistor paste.

[0041] The operating temperature of the high-temperature thin-film electric heating plate is ≥200°C, for example, it can be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C or 300°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] The high-temperature thin-film electric heating plate provided by the present invention achieves efficient heating and an operating temperature of more than 200°C by optimizing and improving the materials of the substrate layer, the conductor layer, the heating layer and the insulating packaging layer. It has high heat transfer efficiency, low thermal resistance and low resistance temperature coefficient, which improves the heating efficiency while reducing the manufacturing cost. The thin-film structure realizes the manufacturing and lightweight design of curved or heterogeneous components, which enables terminal heater manufacturers to perform simplified processing and save labor costs.

[0043] In some embodiments, the substrate layer is a polyimide film.

[0044] In some embodiments, the polyimide film includes a homophenyl polyimide film or a biphenyl polyimide film.

[0045] In some embodiments, the thickness of the polyimide film is 5-125μm, for example, it can be 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm or 125μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] In some embodiments, the conductive silver paste is a high temperature curing conductive silver paste.

[0047] In some embodiments, the square resistance of the high temperature curing conductive silver paste is 1-1000mΩ, for example, it can be 1mΩ, 10mΩ, 100mΩ, 200mΩ, 300mΩ, 400mΩ, 500mΩ, 600mΩ, 700mΩ, 800mΩ, 900mΩ or 1000mΩ, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] In some embodiments, the thickness of the etched copper foil is 2-72 μm, for example, it can be 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm or 72 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0049] The present invention uses etched copper foil as the conductor layer, which can carry and conduct large currents. This is because etched copper foil has excellent stability at high temperatures, has a conductivity close to that of copper metal, and has extremely low resistivity. When the electric heating plate works at high power and needs to pass a large current, the etched copper foil can ensure that the heat is concentrated in the heating layer due to its low resistivity. At the same time, the voltage drop of the copper foil conductor is extremely small, which can ensure that the heating power of different areas of the heating layer is almost consistent.

[0050] In addition, the etched copper foil can be connected to external leads by welding, which makes it more reliable when working under high power and high current.

[0051] In some embodiments, the polymer resistor slurry is composed of a carrier phase and a conductive phase, and the two are mixed evenly by stirring and rolling to obtain the polymer resistor slurry.

[0052] In certain embodiments, the carrier phase is a polymer resin solution.

[0053] In certain embodiments, the polymer resin in the polymer resin solution includes any one of a polyimide resin, a polyetheretherketone resin, or a liquid crystal polymer resin, or a combination of at least two of them. Typical but non-limiting combinations include a combination of a polyimide resin and a polyetheretherketone resin, a combination of a polyetheretherketone resin and a liquid crystal polymer resin, a combination of a polyimide resin and a liquid crystal polymer resin, or a combination of a polyimide resin, a polyetheretherketone resin, and a liquid crystal polymer resin.

[0054] In certain embodiments, the solvent in the polymer resin solution includes any one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or dimethoxybenzene, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of N-methylpyrrolidone and N,N-dimethylformamide, a combination of N,N-dimethylformamide and N,N-dimethylacetamide, a combination of N,N-dimethylacetamide and dimethyl sulfoxide, or a combination of dimethyl sulfoxide and dimethoxybenzene.

[0055] In certain embodiments, the conductive phase includes any one of graphite, carbon black, graphene or metal oxides, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of graphite and carbon black, a combination of carbon black and graphene, or a combination of graphene and metal oxides.

[0056] In some embodiments, the square resistance of the polymer resistor slurry is 1-50000Ω / sq, for example, it can be 1Ω / sq, 100Ω / sq, 1000Ω / sq, 5000Ω / sq, 10000Ω / sq, 15000Ω / sq, 20000Ω / sq, 25000Ω / sq, 30000Ω / sq, 35000Ω / sq, 40000Ω / sq, 45000Ω / sq or 50000Ω / sq, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0057] The present invention uses polymer resistor slurry as the heating layer, and specifically limits the materials of its carrier phase and conductive phase, so that it can work stably at a temperature within 300°C for a long time without causing degradation of the polymer itself in the slurry or changes in resistance. The square resistance of the resistor slurry can be adaptively adjusted in a wide range according to the required heating power, heating area and power density, so that the design of the electric heating sheet has great flexibility and adaptability.

[0058] In some embodiments, the insulating packaging layer is a polyimide resin layer, which can achieve an integrated solution of high temperature resistant insulation and high strength adhesion.

[0059] In some embodiments, the insulating packaging layer is a composite layer of a polyimide adhesive film and a polyimide film, which can achieve reliable bonding in a high temperature environment.

[0060] Compared with epoxy, acrylic and other adhesive materials, the polyimide film still has stable adhesive force at a temperature exceeding 200° C., and the polyimide film itself also has good stability at high temperatures and will not degrade or carbonize.

[0061] An embodiment of the present invention further provides a method for preparing the high-temperature thin-film electric heating sheet described in any of the above embodiments, the method comprising the following steps: (1) A conductive silver paste and / or etched copper foil is provided on the surface of a polyimide substrate layer as a conductor layer; (2) The polymer resistor slurry is coated on the surface of the substrate layer and the conductor layer by a screen printing process or a precision coating process to form a heating layer, and an electrical connection is formed between the conductor layer and the heating layer; (3) The conductor layer and the heating layer are encapsulated by using an insulating encapsulation layer made of polyimide material to obtain a high-temperature thin-film electric heating sheet.

[0062] In some embodiments, the conductive silver paste in step (1) is coated on the surface of the substrate layer by a screen printing process or a precision coating process.

[0063] In some embodiments, the packaging process in step (3) includes any one of the following two methods: (3.1) coating the unimidized polyimide resin coating on the surface of the substrate layer and covering the conductor layer and the heating layer, and performing a drying treatment to achieve imidization of the polyimide resin coating to form a composite structure; (3.2) Covering the composite layer of the polyimide film and the polyimide thin film on the surface of the substrate layer, and the polyimide film covering the conductor layer and the heating layer, the polyimide film is subjected to lamination treatment to melt the polyimide film to produce bonding effect, thereby forming a composite structure.

[0064] In some embodiments, the coating method in step (3.1) includes any one of blade coating, slit coating or gravure coating.

[0065] In some embodiments, the temperature of the drying treatment in step (3.1) is ≥ 280°C, for example, it can be 280°C, 300°C, 320°C, 340°C, 360°C, 380°C or 400°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0066] In some embodiments, the applied pressure of the lamination process in step (3.2) is 0.1-2 MPa, for example, 0.1 MPa, 0.2 MPa, 0.4 MPa, 0.6 MPa, 0.8 MPa, 1 MPa, 1.2 MPa, 1.4 MPa, 1.6 MPa, 1.8 MPa or 2 MPa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0067] In some embodiments, the temperature of the lamination treatment in step (3.2) is 150-300°C, for example, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C or 300°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0068] In some embodiments, the lamination treatment time in step (3.2) is 1-60 min, for example, 1 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0069] An embodiment of the present invention further provides an application of the high-temperature thin-film electric heating plate described in any of the above embodiments, and the application includes: the high-temperature thin-film electric heating plate leads out the circuit through terminal bonding or welding, forms an electrical connection with the power supply, and realizes the heating function.

[0070] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range. Example 1

[0071] This embodiment provides a high temperature thin film type electric heating sheet and a method for preparing the same. Figure 1 As shown, the preparation method comprises the following steps: (1) A 50 μm thick isophthalic polyimide film (molecular weight 150,000 g / mol) is selected as the substrate layer 10, and a high temperature curing conductive silver paste (square resistance 500 mΩ) is prepared on its surface by a screen printing process to form a conductor layer 20 with a specific pattern and a thickness of 30 μm.

[0072] (2) A polymer resistor paste (square resistance of 2000Ω / sq) is applied to the surface of the substrate layer 10 and the conductor layer 20 according to a desired pattern using a screen printing process to form a heating layer 30, and the pattern of the heating layer 30 overlaps with the pattern of the conductor layer 20 according to a desired design to form an electrical connection.

[0073] The polymer resistor paste consists of a carrier phase and a conductive phase; the carrier phase is a polyimide resin solution (molecular weight of 50,000 g / mol, concentration of 15 wt%, solvent is N-methylpyrrolidone); the conductive phase is carbon black, accounting for 10 wt% of the resistor paste.

[0074] (3) The un-imidized polyimide resin coating (molecular weight of 50,000 g / mol, concentration of 15 wt %, solvent of N-methylpyrrolidone) is uniformly coated on the surface of the substrate layer 10 and covers the conductor layer 20 and the heating layer 30 by a doctor blade coating method, and the polyimide resin coating is dried at 280° C. to achieve imidization, thereby forming an insulating packaging layer 40 of a composite structure ( Figure 1 The process route on the left in the middle), that is, the polyimide resin layer, thereby obtaining a high-temperature thin-film electric heating sheet.

[0075] In this embodiment, the screen printing process described in step (1) and step (2) is a conventional technical means in this field. The specific process conditions have no obvious effect on the performance of the electric heating plate obtained in this embodiment, as long as the corresponding layer structure can be successfully prepared. Therefore, the specific process parameters are not specifically described here. Example 2

[0076] This embodiment provides a high temperature thin film type electric heating sheet and a preparation method thereof, such as Figure 1 As shown, the preparation method comprises the following steps: (1) A biphenyl polyimide film (molecular weight 150,000 g / mol) with a thickness of 25 μm was selected as the substrate layer 10, and a copper foil was covered on its surface. The copper foil was then etched to form a conductor layer 20 with a specific pattern and a thickness of 18 μm.

[0077] (2) A polymer resistor paste (square resistance of 500Ω / sq) is applied to the surfaces of the substrate layer 10 and the conductor layer 20 according to a desired pattern using a screen printing process to form a heating layer 30, and the pattern of the heating layer 30 overlaps with the pattern of the conductor layer 20 according to a desired design to form an electrical connection.

[0078] The polymer resistor paste consists of a carrier phase and a conductive phase; the carrier phase is a polyimide resin solution (molecular weight 60000g / mol, concentration 20wt%, solvent N,N-dimethylacetamide); the conductive phase is a mixture of graphite and carbon black, each accounting for 5wt% in the resistor paste.

[0079] (3) A composite layer of a polyimide film 41 (molecular weight of 50,000 / mol) and a polyimide film 42 (molecular weight of 150,000 g / mol) is covered on the surface of the substrate layer 10, and the polyimide film 41 covers the conductor layer 20 and the heating layer 30. The structure is placed in a laminator and the applied pressure is set to 0.5 MPa, the temperature is set to 230°C, and the time is set to 5 min. After lamination, the polyimide film 41 is melted to produce an adhesive effect, thereby forming an insulating packaging layer 40 of a composite structure ( Figure 1 The process route on the right side of the middle) is used to obtain a high-temperature thin-film electric heating plate.

[0080] In this embodiment, the etching process described in step (1) and the screen printing process described in step (2) are both conventional technical means in the field. The specific process conditions have no obvious effect on the performance of the electric heating plate obtained in this embodiment. As long as the corresponding layer structure can be successfully prepared, the specific process parameters are not specifically described here. Example 3

[0081] This embodiment provides a high temperature thin film type electric heating sheet and a method for preparing the same. Figure 1 As shown, the preparation method comprises the following steps: (1) A 50 μm thick isophthalic polyimide film (molecular weight 150,000 g / mol) is selected as the substrate layer 10, and a high temperature curing conductive silver paste (square resistance 50 mΩ) is prepared on its surface by a screen printing process to form a conductor layer 20 with a specific pattern and a thickness of 10 μm.

[0082] (2) A polymer resistor paste (square resistance of 500Ω / sq) is applied to the surfaces of the substrate layer 10 and the conductor layer 20 according to a desired pattern using a screen printing process to form a heating layer 30, and the pattern of the heating layer 30 overlaps with the pattern of the conductor layer 20 according to a desired design to form an electrical connection.

[0083] The polymer resistor paste consists of a carrier phase and a conductive phase; the carrier phase is a polyimide resin solution (molecular weight of 50,000 g / mol, concentration of 10 wt%, solvent N, N-dimethylacetamide); the conductive phase is a mixture of graphene and carbon black, each accounting for 5 wt% in the resistor paste.

[0084] (3) A composite layer of a polyimide film 41 (molecular weight of 50,000 g / mol) and a polyimide film 42 (molecular weight of 150,000 g / mol) is covered on the surface of the substrate layer 10, and the polyimide film 41 covers the conductor layer 20 and the heating layer 30. The structure is placed in a laminator and the applied pressure is set to 0.5 MPa, the temperature is set to 230°C, and the time is set to 5 min. After lamination, the polyimide film 41 is melted to produce an adhesive effect, thereby forming an insulating packaging layer 40 of the composite structure ( Figure 1 The process route on the right side of the middle) is used to obtain a high-temperature thin-film electric heating plate.

[0085] In this embodiment, the screen printing process described in step (1) and step (2) is a conventional technical means in this field. The specific process conditions have no obvious effect on the performance of the electric heating plate obtained in this embodiment, as long as the corresponding layer structure can be successfully prepared. Therefore, the specific process parameters are not specifically described here. Example 4

[0086] This embodiment provides a high-temperature thin-film electric heater and a preparation method thereof. Except that the thickness of the polyimide film in step (1) is changed to 12 μm, the remaining steps and conditions are the same as those in Example 1 and are not described in detail here. Example 5

[0087] This embodiment provides a high-temperature thin-film electric heater and a method for preparing the same. Except that the thickness of the copper foil in step (1) is changed to 9 μm, the remaining steps and conditions are the same as those in Example 2 and are not described in detail here. Example 6

[0088] This embodiment provides a high-temperature thin-film electric heater and a method for preparing the same. Except that the graphene in step (2) is replaced with ruthenium oxide of equal mass, the remaining steps and conditions are the same as those in embodiment 3 and are not described in detail here. Comparative Example 1

[0089] This comparative example provides a thin-film electric heating plate and a preparation method thereof. Except that the polyimide film in step (1) is replaced with a polyester PET film (molecular weight of 25,000 g / mol) of equal thickness, the remaining steps and conditions are the same as those in Example 1 and are not described in detail here. Comparative Example 2

[0090] This comparative example provides a thin-film electric heater and a preparation method thereof. Except that the carrier phase in the polymer resistor slurry in step (2) is changed from a polyimide resin solution to an epoxy resin solution (molecular weight of 50,000 g / mol, concentration of 15 wt%, solvent of N-methylpyrrolidone), the remaining steps and conditions are the same as those in Example 1 and are not described in detail here. Comparative Example 3

[0091] This comparative example provides a thin-film electric heating plate and a preparation method thereof. Except that the carrier phase in the polymer resistor slurry in step (2) is changed from a polyimide resin solution to an acrylic resin solution (molecular weight of 80,000 g / mol, concentration of 15 wt%, solvent of ethyl acetate), the remaining steps and conditions are the same as those in Example 1 and are not described in detail here. Comparative Example 4

[0092] This comparative example provides a thin-film electric heating sheet and a preparation method thereof. Except that the carrier phase in the polymer resistor paste in step (2) is changed from a polyimide resin solution to an ethyl cellulose resin solution (molecular weight of 100,000, concentration of 15 wt%, solvent of pine oil), the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail here. Comparative Example 5

[0093] This comparative example provides a thin-film electric heating plate and a preparation method thereof. Except that the polyimide adhesive film in step (3) is replaced with a common pressure-sensitive adhesive, the remaining steps and conditions are the same as those in Example 2 and are therefore not described in detail here. Comparative Example 6

[0094] This comparative example provides a thin-film electric heating plate and a preparation method thereof. Except that the polyimide film in step (3) is replaced with a polyester PET film (molecular weight of 25,000 g / mol) of equal thickness, the remaining steps and conditions are the same as those in Example 2 and are not described in detail here. Performance Testing

[0095] The thin-film electric heating plates obtained in Examples 1-6 and Comparative Examples 1-6 were respectively led out with circuits through terminal bonding, and electrically connected to a 220V power supply, and the maximum operating temperature of each electric heating plate was tested. The specific test conditions were as follows: after the electric heating plate was electrically connected to the 220V power supply, the power was turned on, a 220V voltage was output to the heating plate instantaneously, and thermal power was generated. A thermal imaging infrared device was used to measure the temperature of the heating plate, and after the power of the heating plate was stabilized, the maximum operating temperature was recorded.

[0096] The relevant test results are shown in Table 1 below.

[0097] Table 1

[0098] It can be seen from Table 1 that Examples 1-6 use polyimide substrate layers and insulating packaging layers, combined with polyimide resin-based resistor paste, to achieve an operating temperature of more than 200° C. In contrast, the replacement of polyimide materials in Comparative Examples 1-6 resulted in a significant decrease in operating temperature.

[0099] It can be seen that the high-temperature thin-film electric heating plate provided by the present invention achieves efficient heating and an operating temperature of more than 200°C by optimizing and improving the materials of the substrate layer, the conductor layer, the heating layer and the insulating packaging layer. It has high heat transfer efficiency, low thermal resistance and low resistance temperature coefficient, which improves the heating efficiency while reducing the manufacturing cost. The thin-film structure realizes the manufacturing and lightweight design of curved or heterogeneous components, which enables terminal heater manufacturers to simplify processing and save labor costs.

[0100] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A high-temperature thin-film electric heating sheet, comprising a substrate layer, a conductor layer, a heating layer and an insulating packaging layer arranged in sequence, characterized in that: The materials of the substrate layer and the insulating packaging layer independently include polyimide, the material of the conductor layer includes conductive silver paste and / or etched copper foil, and the material of the heating layer includes polymer resistor paste; The working temperature of the high temperature thin film type electric heating plate is ≥200°C.

2. The high temperature thin film type electric heating sheet according to claim 1, characterized in that: The substrate layer is a polyimide film; And / or, the polyimide film comprises a homophenyl polyimide film or a biphenyl polyimide film; And / or, the polyimide film has a thickness of 5-125 μm.

3. The high temperature thin film type electric heating sheet according to claim 1, characterized in that: The conductive silver paste is a high temperature curing conductive silver paste; And / or, the sheet resistance of the high temperature curing conductive silver paste is 1-1000 mΩ; And / or, the etched copper foil has a thickness of 2-72 μm.

4. The high temperature thin film type electric heating sheet according to claim 1, characterized in that: The polymer resistor slurry consists of a carrier phase and a conductive phase; Wherein, the carrier phase is a polymer resin solution; And / or, the polymer resin in the polymer resin solution includes any one of polyimide resin, polyetheretherketone resin or liquid crystal polymer resin, or a combination of at least two thereof; and / or, the solvent in the polymer resin solution comprises any one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or dimethoxybenzene, or a combination of at least two thereof; And / or, the conductive phase comprises any one of graphite, carbon black, graphene or metal oxide, or a combination of at least two thereof; And / or, the sheet resistance of the polymer resistor slurry is 1-50000Ω / sq.

5. The high temperature thin film type electric heating sheet according to claim 1, characterized in that: The insulating packaging layer is a polyimide resin layer; Alternatively, the insulating packaging layer is a composite layer of a polyimide adhesive film and a polyimide film.

6. A method for preparing a high-temperature thin-film electric heating sheet as claimed in any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) A conductive silver paste and / or etched copper foil is provided on the surface of a polyimide substrate layer as a conductor layer; (2) The polymer resistor slurry is coated on the surface of the substrate layer and the conductor layer by a screen printing process or a precision coating process to form a heating layer, and an electrical connection is formed between the conductor layer and the heating layer; (3) The conductor layer and the heating layer are encapsulated by using an insulating encapsulation layer made of polyimide material to obtain a high-temperature thin-film electric heating sheet.

7. The preparation method according to claim 6, characterized in that: Step (1) The conductive silver paste is coated on the surface of the substrate layer by screen printing or precision coating; And / or, the packaging process in step (3) includes any one of the following two methods: (3.1) coating the unimidized polyimide resin coating on the surface of the substrate layer and covering the conductor layer and the heating layer, and performing a drying treatment to achieve imidization of the polyimide resin coating to form a composite structure; (3.2) Covering the composite layer of the polyimide film and the polyimide thin film on the surface of the substrate layer, and the polyimide film covering the conductor layer and the heating layer, the polyimide film is subjected to lamination treatment to melt the polyimide film to produce bonding effect, thereby forming a composite structure.

8. The preparation method according to claim 7, characterized in that: The coating method in step (3.1) includes any one of blade coating, slit coating or gravure coating; And / or, the temperature of the drying treatment in step (3.1) is ≥ 280°C.

9. The preparation method according to claim 7, characterized in that: The applied pressure of the lamination process in step (3.2) is 0.1-2 MPa; and / or, the temperature of the lamination process in step (3.2) is 150-300°C; And / or, the lamination treatment time in step (3.2) is 1-60 min.

10. An application of the high temperature thin film electric heating sheet as claimed in any one of claims 1 to 5, characterized in that: The application includes: the high-temperature thin-film electric heating sheet leads out the circuit through terminal bonding or welding, forms an electrical connection with a power source, and realizes a heating function.

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