Surface heating element and electronic device comprising same

Abstract

This disclosed surface heating element comprises: a substrate; a graphene heating element disposed on the substrate; and a first electrode and a second electrode spaced apart from each other on the graphene heating element and including a conductive paste including a conductive material and glass frit. A plurality of through-holes are formed, among regions of the graphene heating element, in a region in contact with the first electrode and a region in contact with the second electrode, the first electrode and the second electrode are formed to extend from an upper surface of the graphene heating element into the plurality of through-holes, and glass frit made of the same material as the glass frit included in the conductive paste may be included in the substrate.

Description

Planar heating element and electronic device including the same

[0001] The present disclosure relates to a planar heating element and an electronic device including the same.

[0002] Conventional planar heating elements that generate heat when electricity is applied are not only hygienic as they do not contaminate the air, but also easy to control their temperature and are noiseless, so they are widely used in residential heating devices such as apartments and general houses that require heating, as well as in cooking heating devices. For example, an electric oven, which is one of the cooking heating devices, can use an electric heater as a heat source, and in this case, a planar heating element can be used as the electric heater.

[0003] These planar heating elements are equipped with electrodes for applying electricity, and there are issues such as contact resistance and durability in high-temperature environments.

[0004] A planar heating element according to one example may include a substrate, a graphene heating element disposed on the substrate, and a first electrode and a second electrode spaced apart on the graphene heating element.

[0005] The first electrode and the second electrode may be made of a conductive paste containing a conductive material and a glass frit.

[0006] Among the regions of the graphene heating element, a plurality of through holes may be formed in the region in contact with the first electrode and the region in contact with the second electrode.

[0007] The first electrode and the second electrode may be formed to extend from the upper surface of the graphene heating element into the interior of the plurality of through holes, and a glass frit of the same material as the glass frit included in the conductive paste may be included inside the substrate.

[0008] An electric oven according to one example may include a top plate, a bottom plate, two side plates and a rear plate arranged to face each other, and may include a cavity with an open front.

[0009] Additionally, an electric oven according to one example may further include a door that selectively opens and closes the front of the cavity.

[0010] Additionally, an electric oven according to one example may further include a planar heating element disposed on one or more of the top plate, the bottom plate, the two side plates and the rear plate to apply heat to the cavity.

[0011] A method for manufacturing a planar heating element according to one example may include the steps of: forming a graphene heating element on a substrate; forming a plurality of through holes in two spaced-apart regions of the graphene heating element; and printing a conductive paste on each of the two regions to form a first electrode and a second electrode.

[0012] A method for manufacturing a planar heating element according to one example may further include the step of heat-treating a structure comprising a substrate, a graphene heating element, a first electrode, and a second electrode.

[0013] FIG. 1 is a plan view schematically showing a planar heating element according to one embodiment.

[0014] FIG. 2a is a plan view exemplarily showing the division of regions of a graphene heating element provided in the planar heating element of FIG. 1.

[0015] FIG. 2b is a plan view showing an enlarged and detailed view of a portion of FIG. 2a.

[0016] FIG. 3 is a cross-sectional view showing in detail a portion of a planar heating element according to one embodiment.

[0017] Figures 4 and 5 are transmission electron microscope images showing the physical properties of a portion of Figure 3.

[0018] Figure 6 is a graph showing a comparison of the thermal analysis results for an electrode provided in a planar heating element of one embodiment and a general electrode.

[0019] FIGS. 7A and 7B show micrographs of the surface heating element according to one embodiment, before and after heat treatment when electrodes are formed by printing a conductive paste.

[0020] Figures 8a and 8b show micrographs of the electrode of the comparative example before and after heat treatment, respectively.

[0021] Figures 9a and 9b show micrographs of electrodes of other comparative examples before and after heat treatment, respectively.

[0022] Figures 10a and 10b show micrographs of an electrode of another comparative example before and after heat treatment, respectively.

[0023] FIGS. 11a to 11d exemplarily show a graphene heating element that can be employed in a planar heating element according to an embodiment.

[0024] FIGS. 12a to 12e are drawings illustrating a method for manufacturing a planar heating element according to an embodiment.

[0025] FIG. 13 is a drawing illustrating an electric oven according to an embodiment.

[0026] Figure 14 is a schematic drawing showing the cross-section of Figure 13.

[0027] Embodiments of the present disclosure are described below in detail with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present disclosure may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present disclosure in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0028] Throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "electrically connected" with other components interposed between them. Furthermore, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0029] Additionally, terms such as “...part” described in the specification refer to a unit that processes at least one function or operation, which may be implemented in hardware or software, or as a combination of hardware and software.

[0030] The terms used in the embodiments of this specification have been selected to be as widely used as possible, taking into account the functions of the present disclosure; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the description section of the relevant embodiments. Therefore, terms used in this specification should be defined not merely by their names, but based on their meanings and the overall content of the present disclosure.

[0031] FIG. 1 is a schematic plan view showing a planar heating element according to one embodiment, FIG. 2a is a plan view showing an exemplary division of a graphene heating element provided in the planar heating element of FIG. 1, and FIG. 2b is a plan view showing a detailed enlarged view of a part of FIG. 2a.

[0032] The planar heating element (100) includes a substrate (110), a graphene heating element (120) disposed on the substrate (110), and a first electrode (140) and a second electrode (160) spaced apart on the graphene heating element (120).

[0033] The substrate (110) may be made of various transparent materials. The substrate (110) may include glass, reinforced glass, ceramic, or quartz.

[0034] The graphene heating element (120) contains graphene. Graphene is a material in which carbon atoms form a honeycomb-shaped two-dimensional planar structure and has very high electrical and thermal conductivity. When current flows through the graphene heating element (120), resistive heating (Joule heating) occurs due to the movement of electrons inside the graphene, and heat is generated on the surface of the graphene heating element (120). This heat can be evenly distributed on the surface of the graphene heating element (120).

[0035] The graphene heating element (120) may include a plurality of graphene layers. The graphene heating element (120) may further include a graphene oxide film, a metal film, or a metal oxide film together with the plurality of graphene layers. The thickness of the graphene heating element (120) may be approximately 1 nm or more and 10 nm or less. However, it is not limited thereto.

[0036] The first electrode (140) and the second electrode (160) may each be made of a conductive paste. The conductive paste may include a conductive material and a glass frit. The conductive material may include, for example, Ag, Al, ITO (Indium Tin Oxide), Cu, Mo, or Pt. The glass frit may include, for example, Bi. The glass frit may include, for example, PbO, Bi2O3, TeO2, SiO2, B2O3, or ZnO, TeO2. However, it is not limited thereto.

[0037] The first electrode (140) and the second electrode (160) can be connected to an unillustrated power supply, and accordingly, the planar heating element (100) can be heated.

[0038] The first electrode (140) and the second electrode (160) are spaced apart in the first direction (Y direction) and extended in the second direction (X direction) perpendicular to it. The area of ​​the first electrode (140) and the second electrode (160) can be determined by considering the reduction of contact resistance with the graphene heating element (120) and the heating efficiency in the graphene heating element (120). The extended length of the first electrode (140) and the second electrode (160), that is, the length in the X direction, may be greater than or equal to the length in the X direction of the graphene heating element (120). The width of the first electrode (140) and the second electrode (160), that is, the width of the first electrode (140) and the second electrode (160) in the first direction (Y direction), may be approximately 10 μm or more. The width of the first electrode (140) and the second electrode (160) may be determined in relation to the width of the first direction of the graphene heating element (120), for example, it may be 20% or less of the width of the first direction of the graphene heating element (120). However, it is not limited thereto.

[0039] Among the regions of the graphene heating element (120), a plurality of through holes (HO) are formed in the region (120a) that contacts the first electrode (140) and the second electrode (160).

[0040] These through holes (HO) can be provided to increase the contact area between the first electrode (140), the second electrode (160), and the graphene heating element (120) to lower the contact resistance. Additionally, the first electrode (140) and the second electrode (160) can be efficiently adhered to the graphene heating element (120) through these through holes (HO). For example, the problem of electrode material loss due to the high-temperature environment in which the planar heating element (100) is heated hardly occurs.

[0041] The through holes (HO) may be distributed generally evenly within the contact area (120a), but are not limited to the distribution pattern shown. For example, the directions of D1 and D2 shown in FIG. 2b may be any direction perpendicular to the Z direction. The through holes (HO) may be distributed irregularly, and their size or shape may not be uniform.

[0042] The spacing (S1, S2) of the through holes (HO) and their respective diameters (R) can be appropriately determined in terms of contact resistance and high-temperature reliability. At this time, details of the material forming the graphene heating element (120) can be taken into account. For example, depending on the work function of the material forming the graphene heating element (120), the degree to which the through holes (HO) contribute to the reduction of contact resistance may vary.

[0043] Through holes (HO) are depicted as having a circular cross-section, but this is exemplary and not limited thereto. The cross-sections of the through holes (HO) may be elliptical or polygonal, or may have an irregular shape.

[0044] The diameter of the through hole (HO) may be greater than 0 and less than or equal to 100 µm. The spacing between adjacent through holes (HO) may be greater than or equal to 1 µm and less than or equal to 1000 µm.

[0045] FIG. 3 is a cross-sectional view showing in detail a portion of a planar heating element (100) according to one embodiment.

[0046] FIG. 3 shows in detail the contact area (120a) with the first electrode (140) and the second electrode (160) among the regions of the graphene heating element (120), and the direction D1 may be any direction perpendicular to the Z direction.

[0047] The first electrode (140) and the second electrode (160) are formed to extend from the upper surface of the graphene heating element (120) into a plurality of through holes (HO) formed in the contact area (120a) of the graphene heating element (120). Accordingly, the contact between the first electrode (140) and the graphene heating element (120), and the contact between the second electrode (160) and the graphene heating element (120) include planar contact and edge contact, and the overall contact area is increased by the through holes (HO). As the contact area between the electrode material and the graphene material increases in this way, the contact resistance between the first electrode (140), the second electrode (160), and the graphene heating element (120) is reduced. In addition, as the contact area between the graphene heating element (120), the first electrode (140), and the second electrode (160) is secured in this way, the current concentration phenomenon can be improved. The current concentration phenomenon is a phenomenon in which current is concentrated in a certain area. That is, it means that the current density is not evenly distributed and shows a very high density in some areas, and in this case, the graphene heating element (120) does not heat up evenly, and a specific location may overheat. By improving the current concentration phenomenon, the current density is well distributed over the entire surface of the graphene heating element (120), and efficient heating can occur.

[0048] In addition, the interfacial contact instability caused by the difference in thermal expansion coefficients between the graphene material and the electrode material can be improved by these through holes (HO). In other words, during the high-temperature operation and room-temperature reduction process of the planar heating element (100), the contact state between the graphene heating element (120) and the first electrode (140) is not well maintained due to the difference in thermal expansion coefficients between the graphene heating element (120) and the first electrode (140), and damage such as a portion of the material forming the first electrode (140) falling off from the graphene heating element (120) may occur, but such damage can be minimized by the through holes (HO).

[0049] In the process of forming the first electrode (140) and the second electrode (160) inside the substrate (110), a portion of the glass frit contained in the first electrode (140) and the second electrode (160) moves into the substrate (110), thereby forming a fusion region (114). The process of forming the first electrode (140) and the second electrode (160) with a conductive paste includes a high-temperature firing process, at which time the glass frit contained in the first electrode (140) and the second electrode (160) can diffuse into the substrate (110) through a through hole (HO). A low contact resistance is provided by the form in which the first electrode (140) and the second electrode (160) come into contact with the graphene heating element (120) through the through hole (HO). Additionally, the process of forming the first electrode (140) and the second electrode (160) provides high-temperature diffusion bonding between the first electrode (140), the second electrode (160), and the substrate (110). High-temperature diffusion bonding means that two types of materials are bonded at a high temperature below their melting point. Bonding is achieved using atomic diffusion between bonding surfaces, and since bonding occurs at a temperature below the melting point, no deformation occurs. In the embodiment, among the materials forming the first electrode (140) and the second electrode (160), the glass frit moves toward the substrate to form a fusion region (114). It is analyzed that due to this fusion region (114), the adhesion of the first electrode (140) to the graphene heating element (120) and the substrate (110) is increased. In addition, even when the planar heating element (100) operates at a high temperature, the adhesion between the first electrode (140), the graphene heating element (120), and the substrate (110) is maintained and high-temperature durability can be ensured by the material of the conductive paste that is resistant to high temperatures and the structure having a plurality of through holes (HO).

[0050] Figures 4 and 5 are micrographs showing the physical properties of a portion of Figure 3.

[0051] The conductive paste forming the first electrode (140) contains Ag and Bi, and for region A shown in FIG. 3, FIG. 4 is a photograph of the Ag component and FIG. 5 is a photograph of the Bi component.

[0052] Referring to FIG. 4, it is confirmed that the Ag component is detected only on the interface (110a) between the substrate (110) and the graphene heating element (120).

[0053] Referring to FIG. 5, it is confirmed that the Bi component, which is a glass frit included in the conductive paste, is mostly distributed on the interface (110a), but is also distributed in the fusion region (114) below the interface (110a). That is, it can be seen that some of the glass frit included in the conductive paste forming the first electrode (140) and the second electrode (160) moves into the substrate (110) to form the fusion region (114).

[0054] The following table experimentally shows that the contact resistance is improved when through holes are provided in the contact area of ​​a graphene heating element.

[0055] Contact Area Graphene Sheet Resistance Electrode Resistance Resistance Improvement Rate Theoretical Value Measured Value Comparison Example (General Graphene) 100% 536 Ω / sq 131 Ω 130 Ω Example 1 103.8% 606 Ω / sq 148 Ω 112 Ω 24% Example 2 101.9% 643 Ω / sq 157 Ω 144 Ω 8%

[0056] In the table above, the comparative example general graphene is a case where through holes are not provided in the contact area with the electrode, Example 1 is a case where through holes with a diameter of approximately 15 to 20 μm are formed at intervals of 50 μm, and Example 2 is a case where through holes with a diameter of approximately 15 to 20 μm are formed at intervals of 100 μm.

[0057] The contact area is the area where the graphene heating element (120) and the first electrode (140) (or second electrode (160)) come into contact, and the contact areas of the two embodiments are expressed relatively based on the case of general graphene without through holes (100%).

[0058] Sheet resistance is the resistance per unit area and is typically used to measure the resistance of thin films. Once the sheet resistance of a film is measured, the resistance of the film of any shape can be calculated, as shown in the following equation.

[0059]

[0060] Here, the length is the length in the direction of current flow, and the width is the width in the direction perpendicular to this length.

[0061] In the table above, the graphene sheet resistance represents the sheet resistance of the graphene used in each case, and the theoretical value is the theoretical resistance calculated from the graphene sheet resistance according to the above formula, i.e., a value that does not take through-holes into account.

[0062] Electrode resistance is a concept that includes contact resistance at the location where the electrode material contacts the graphene material and resistance in the part excluding the contact location with the graphene material. Here, since the latter resistance is the same in the Comparative Example, Example 1, and Example 2, the change in the measured value of electrode resistance is analyzed to be due to the change in contact resistance.

[0063] The resistance improvement rate refers to the rate of resistance reduction of the measured value relative to the theoretical value; since the theoretical value does not account for through-holes, it means the resistance reduction rate compared to standard graphene.

[0064] In the case of Examples 1 and 2, which are equipped with through holes, lower electrode resistance is exhibited compared to the case without through holes, and in the case of Example 1, where the spacing between the through holes is smaller, lower electrode resistance is exhibited. These experimental results are the result of the contact resistance component of the electrode resistance being lowered by the provision of through holes in the contact area. However, the interpretation is not limited to the fact that the electrode resistance decreases as the spacing between the through holes becomes smaller.

[0065] Figure 6 is a graph showing a comparison of the thermal analysis results for an electrode provided in a planar heating element of one embodiment and a general electrode.

[0066] The electrode of the example made of a conductive paste does not exhibit a change in weight even when the temperature increases.

[0067] In contrast, in the case of the electrode of the comparative example, that is, a general electrode that does not contain glass frit, weight loss is confirmed as a result of rapid loss above a certain temperature.

[0068] FIGS. 7 and 7b are micrographs of a planar heating element according to one embodiment, showing the state before and after heat treatment when electrodes are formed by printing a conductive paste.

[0069] Figure 7b is a micrograph of the conductive paste printed as in Figure 7a and then fired at 500 degrees.

[0070] Comparing Fig. 7a and Fig. 7b, it is confirmed that metal migration, which appears in the comparative examples described later, is not observed and that the electrode quality is maintained.

[0071] Figures 8a and 8b show micrographs of the electrode of the comparative example before and after heat treatment, respectively.

[0072] Figures 8a and 8b show the Ti / Ag electrode formed by the sputtering method, before and after heat treatment. The heat treatment conditions were 400°C for 2 hours. It is confirmed that metal migration occurred following the heat treatment.

[0073] Figures 9a and 9b show micrographs of electrodes of other comparative examples before and after heat treatment, respectively.

[0074] Figures 9a and 9b show the Ti / Cu electrode formed by the sputtering method, before and after heat treatment. After heat treatment at 400°C for 2 hours, it is confirmed that metal migration occurred.

[0075] Figures 10a and 10b show micrographs of an electrode of another comparative example before and after heat treatment, respectively.

[0076] Figures 10a and 10b show the Ti / Au electrode formed by the sputtering method, before and after heat treatment. After heat treatment at 400°C for 2 hours, it is confirmed that metal migration occurred.

[0077] The meta migration observed in these experimental results is also confirmed by an increase in electrical resistance. While the electrode of the example made of conductive paste exhibited a resistance of 0.4Ω, the electrodes of the comparative example were found to exhibit a resistance of approximately 3.5 to 4Ω after heat treatment.

[0078] In the case of an electrode formed from a conductive paste material containing glass frit, there is almost no change in resistance due to heat treatment, but in the case of comparative examples formed by sputtering without glass frit, reliability is very low in a high-temperature environment and also exhibits high resistance.

[0079] FIGS. 11a to 11d exemplarily show a graphene heating element that can be employed in a planar heating element according to an embodiment.

[0080] Referring to FIG. 11a, the graphene heating element (120) may include a plurality of graphene layers (1). The thickness of one graphene layer (1) may be approximately 0.2 nm, and the number of stacked graphene layers (1) may be several to tens. The number of stacked graphene layers (1) is not limited to the number shown and may be set considering an appropriate heating effect.

[0081] Referring to FIGS. 11b and FIGS. 11c, the graphene heating element (120) may include a metal layer (2) and a plurality of graphene layers (1). The metal layer (2) may be placed on the upper or lower side of the plurality of graphene layers (1).

[0082] Referring to FIG. 11d, the graphene heating element (120) may include a metal oxide layer (3) and a plurality of graphene layers (1). The metal oxide layer (3) may be placed on the plurality of graphene layers (1). Unlike what is shown, the position of the metal oxide layer (3) may be changed to the lower part of the plurality of graphene layers (1).

[0083] In addition, in other embodiments, the graphene heating element may include a metal film, a metal oxide film, or a graphene oxide film together with a plurality of graphene layers (1).

[0084] FIGS. 12a to 12d are drawings illustrating a method for manufacturing a planar heating element according to an embodiment.

[0085] Referring to FIG. 12a, a graphene heating element (120) is provided on a substrate (110).

[0086] The graphene heating element (120) may include a plurality of graphene layers. The plurality of graphene layers may be manufactured separately and transferred onto the substrate (110). However, they are not limited thereto and may be grown directly on the substrate (110). The substrate (110) may include glass, ceramic, or quartz. However, it is not limited thereto.

[0087] The graphene heating element (120) may further include other material layers, such as a metal oxide film, a metal film, or a graphene oxide film, in addition to a plurality of graphene layers, and may have a structure or a modified structure as illustrated in FIGS. 11a to 11d, for example. Additional material layers may be formed before or after forming a plurality of graphene layers on the substrate (110).

[0088] Referring to FIG. 12b, two spaced-apart regions on the graphene heating element (120) are defined as contact regions (120a). A plurality of through holes (HO) are formed in the contact regions (120a). The through holes (HO) can be formed by etching the graphene heating element (120). Gas plasma or a laser may be used in the etching process. The through holes (HO) may have a circular cross-section, or an elliptical or polygonal cross-sectional shape. The cross-sectional shape of the through holes (HO) may be irregular, and the arrangement may also be irregular. The number or spacing of the through holes (HO) may be determined by considering the detailed material of the graphene heating element (120).

[0089] Referring to FIG. 12c, a conductive paste is printed on two contact areas (120a) to form a first electrode (140) and a second electrode (160).

[0090] Referring to FIG. 12d, heat treatment is performed. After placing the substrate (110) on which the graphene heating element (120), the first electrode (140), and the second electrode (160) are formed in a high-temperature chamber, heat treatment can be performed. The heat treatment temperature may be approximately 450°C to 550°C.

[0091] Referring to FIG. 12e, it is shown that glass frit (GF) contained in the conductive paste has moved into the substrate (110) and formed a fusion region (114). The fusion region (114) is shown at a position aligned with the through hole (HO), but this is exemplary. Depending on the heat treatment conditions, the fusion region (114) may be more widely distributed within the substrate (110), and the position, width, and depth of the fusion region (114) are not limited to the illustrated form.

[0092] The above-described planar heating element is a transparent planar heating element and can be applied to various electronic devices.

[0093] FIG. 13 is a drawing illustrating an electric oven according to one embodiment. FIG. 14 is a drawing schematically showing a cross-sectional view of FIG. 13.

[0094] Referring to FIGS. 13 and 14, an electric oven (1000) according to one example may include a case (10) and a cavity (20) provided inside the case (10) to have a front opening. The electric oven (1000) may form an exterior by having a door (30) rotatably coupled to one side of the case (10) to open and close the front opening of the cavity (20).

[0095] The case (10) may be positioned so as to be spaced apart from the cavity (20), which will be described later, by a predetermined distance. According to one example, the case (10) may include a transparent substrate. According to one example, if the case (10) is made of a transparent substrate, the internal condition of the cavity (20) can be observed from the outside. According to one example, the case (10) may include one or more of tempered glass, ceramic, and quartz. However, the present disclosure is not limited thereto, and the case (10) may include any transparent material capable of transmitting visible light so that an external user can observe the inside of the cavity (20).

[0096] The cavity (20) is a cooking space formed by the top plate (21), bottom plate (22), two side plates (23), and rear plate (24). A front plate (27) forming a front opening may be provided on the front of the cavity (20). According to one example, the case (10) may be positioned so as to be spaced apart from the top plate (21), bottom plate (22), two side plates (23), and rear plate (24) by a predetermined distance. Various components constituting an electric oven (1000) may be installed in the space provided between the cavity (20) and the case (10), for example, the space provided between the case (10) and one or more of the top plate (21), bottom plate (22), two side plates (23), and rear plate (24).

[0097] At least one rack (90) for placing food can be placed inside the cavity (20). Rails (not shown) can be installed on the inner sides of both side plates (23) so that the rack (90) can be attached and detached. The user can move the rack (90) along the rails (91) to take out or place food.

[0098] The door (30) can be installed by hinge-connecting it to the bottom of the case (10) so that the user can open and close the cavity (20). A handle (37) can be attached to the top of the door (30) so that the user can conveniently rotate the door (30).

[0099] A vent (92) may be installed in the rear plate (24) to allow the air inside the cavity (20) to escape to the outside. The vent (92) may be formed by penetrating the rear plate (24) to allow the air inside the cavity (20) to pass through. A filter (not shown) capable of filtering contaminants from the air escaping from the cavity (20) may be installed in the vent (92).

[0100] A planar heating element (100) is a heating element that is positioned between a case (10) and a cavity (20) and can apply heat to the cavity (20). As an example, the planar heating element (100) may be formed as one or more, and each of the one or more planar heating elements (100) may be positioned to face any one of the top plate (21), bottom plate (22), two side plates (23), and rear plate (24) provided in the cavity (20). Alternatively, any one of the top plate (21), bottom plate (22), two side plates (23), and rear plate (24) may directly constitute the planar heating element.

[0101] The planar heating element (100) may have a structure as previously described in FIGS. 1 to 12e and may be manufactured by the described method. The planar heating element (100) is 400 0It can be heated to a high temperature of C or higher. Five planar heating elements (100) may be provided within the electric oven (1000). As described above, the planar heating elements (100) are provided to ensure high-temperature reliability and durability and to have an efficient current density distribution structure, so that not only can the heating rate inside the cavity (20) be increased, but the temperature inside the cavity (20) can also be raised uniformly.

[0102] In order to insulate the cavity (20) from the outside, an insulating part (50) may be placed between the top plate (21), bottom plate (22), two side plates (23), and rear plate (24) forming the cavity (20) and the case (10). Additionally, a control panel (60) for controlling the operation of the electric oven (1000) may be installed on the top part of the case (10).

[0103] The insulation member (50) can block heat transfer between the case (10) and the planar heating element (100) so that heat generated from the planar heating element (100) is not transferred to the user. According to one example, when the planar heating element (100) is placed in a spaced-out space formed between the case (10) and the top plate (21), bottom plate (22), two side plates (23), and rear plate (24), the insulation member (50) is placed between the case (10) and the top plate (21), bottom plate (22), and two side plates (23) to insulate the cavity (20) from the outside.

[0104] According to one example, the insulating part (50) may include a transparent material. As described above, when the substrate forming the case (10), the planar heating element (100), and the cavity (20) is implemented as a transparent structure capable of transmitting visible light, the insulating part (50) disposed in the space between the case (10) and the cavity (20) may also include a transparent material. According to one example, the insulating part (50) may include one or more of tempered glass, ceramic, and quartz. However, the present disclosure is not limited thereto, and the insulating part (50) may include any transparent material capable of transmitting visible light so that an external user can observe the inside of the cavity (20).

[0105] The foregoing description of the present disclosure is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present disclosure. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0106] According to an embodiment, a planar heating element is provided in which the contact area between the graphene and the electrode is secured, thereby reducing contact resistance and improving current density.

[0107] According to an embodiment, a planar heating element with high temperature reliability and durability is provided.

[0108] According to an embodiment, a transparent planar heating element is provided.

[0109] According to an embodiment, a planar heating element is provided, comprising a substrate, a graphene heating element disposed on the substrate; and a first electrode and a second electrode spaced apart on the graphene heating element and made of a conductive paste comprising a conductive material and a glass frit, wherein a plurality of through holes are formed in a region of the graphene heating element that contacts the first electrode and a region that contacts the second electrode, and the first electrode and the second electrode are formed to extend from the upper surface of the graphene heating element into the interior of the plurality of through holes, and a glass frit of the same material as the glass frit included in the conductive paste is included inside the substrate.

[0110] The diameter of the above through hole may be greater than 0 and less than or equal to 100㎛.

[0111] The spacing between adjacent through holes among the above plurality of through holes may be 1 μm or more and 1000 μm or less.

[0112] The thickness of the graphene heating element may be 1 nm or more and 10 nm or less.

[0113] The graphene heating element may include a plurality of graphene layers.

[0114] The graphene heating element may include a metal layer and a plurality of graphene layers.

[0115] The graphene heating element may include a metal oxide layer and a plurality of graphene layers.

[0116] The above conductive paste may include Ag, Al, ITO (Indium Tin Oxide), Cu, Mo, or Pt.

[0117] The above conductive paste may contain Bi.

[0118] The above substrate may include glass, ceramic, or quartz.

[0119] When the direction in which the first electrode and the second electrode are separated is called the first direction,

[0120] The width of the first direction of the first electrode and the second electrode may each be 20% or less of the width of the first direction of the graphene heating element.

[0121] According to an embodiment, an electric oven is provided comprising: a cavity having an open front surface and having a top plate, a bottom plate, two side plates and a rear plate; a door for selectively opening and closing the front surface of the cavity; and one of the aforementioned planar heating elements disposed on one or more of the top plate, the bottom plate, the two side plates and the rear plate to apply heat to the cavity.

[0122] According to an embodiment, a method for manufacturing a planar heating element is provided, comprising: a step of forming a graphene heating element on a substrate; a step of forming a plurality of through holes in two spaced-apart regions of the graphene heating element; a step of printing a conductive paste on each of the two regions to form a first electrode and a second electrode; and a step of heat-treating a structure including the substrate, the graphene heating element, the first electrode, and the second electrode.

[0123] The above conductive paste may include a conductive material and a glass frit.

[0124] The above substrate may include glass, ceramic, or quartz.

[0125] The step of forming the plurality of through holes above may use gas plasma or a laser.

[0126] The diameter of the above through hole may be greater than 0 and less than or equal to 100㎛.

[0127] The graphene heating element may include a plurality of graphene layers.

[0128] The graphene heating element may include a metal layer and a plurality of graphene layers.

[0129] The graphene heating element may include a metal oxide layer and a plurality of graphene layers.

[0130] The aforementioned planar heating element, method for manufacturing a planar heating element, and electronic device including the same have been described with reference to the embodiments illustrated in the drawings for the sake of understanding; however, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Therefore, the disclosed embodiments should be considered in an illustrative rather than a limiting sense. The scope of this specification is defined by the claims, not by the foregoing description, and all variations within the scope of equivalents should be interpreted as being included.

Claims

Substrate (110); A graphene heating element (120) disposed on the substrate; and It includes a first electrode (140) and a second electrode (160) spaced apart on the graphene heating element and made of a conductive paste comprising a conductive material and glass frit; A plurality of through holes are formed in the region of the graphene heating element that contacts the first electrode and the region that contacts the second electrode, and The first electrode and the second electrode are formed to extend from the upper surface of the graphene heating element into the interior of the plurality of through holes, and A planar heating element comprising, within the substrate, a glass frit of the same material as the glass frit included in the conductive paste In paragraph 1, A planar heating element having a diameter of the through hole greater than 0 and less than or equal to 100㎛. In paragraph 1, A planar heating element in which the spacing between adjacent through holes among the plurality of through holes is 1㎛ or more and 1000㎛ or less. In paragraph 1, A planar heating element having a thickness of 1 nm or more and 10 nm or less of the graphene heating element. In paragraph 1, The graphene heating element is a planar heating element comprising a plurality of graphene layers. In paragraph 1, The graphene heating element is a planar heating element comprising a metal layer and a plurality of graphene layers. In paragraph 1, The graphene heating element is a planar heating element comprising a metal oxide layer and a plurality of graphene layers. In paragraph 1, The above conductive paste is a planar heating element comprising Ag, Al, ITO (Indium Tin Oxide), Cu, Mo, or Pt. In paragraph 1, The above conductive paste is a planar heating element containing Bi. In paragraph 1, The above substrate is a planar heating element comprising glass, ceramic, or quartz. In paragraph 1, When the direction in which the first electrode and the second electrode are separated is called the first direction, The width of the first electrode and the second electrode in the first direction is, respectively A planar heating element having a width of 30% or less of the first direction of the graphene heating element. A cavity (20) having a top plate, a bottom plate, two side plates and a rear plate, with an open front; A door (30) for selectively opening and closing the front of the cavity; and An electric oven comprising: a planar heating element (100) according to any one of claims 1 to 11, disposed on one or more of the upper plate, the bottom plate, the two side plates and the rear plate, and applying heat to the cavity. Step of forming a graphene heating element on a substrate; A step of forming a plurality of through holes in two spaced-apart regions of the graphene heating element; A step of forming a first electrode and a second electrode by printing a conductive paste on each of the two regions above; and A method for manufacturing a planar heating element comprising the step of heat-treating a structure including the above substrate, a graphene heating element, a first electrode, and a second electrode. In Paragraph 13, A method for manufacturing a planar heating element, wherein the conductive paste comprises a conductive material and a glass frit. In Paragraph 13, A method for manufacturing a planar heating element, wherein the step of forming the plurality of through holes above uses gas plasma or a laser.

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