Silicon nitride ceramic heater

Abstract

The utility model discloses a silicon nitride ceramic heater, and relates to the technical field of ceramic heating. Comprising a ceramic laminated plate which is formed by laminating a plurality of ceramic layers, a heating circuit which is arranged between two adjacent ceramic layers and has a folded shape, a connecting circuit which is arranged between the adjacent heating circuit and the ceramic laminated plate, and a plurality of through holes which are uniformly distributed and penetrate through the heating circuit and the connecting circuit, the width of the connecting circuit is larger than that of the heating circuit, and the two ends of the connecting circuit extend to the two sides of the ceramic laminated plate; the two ends of the heating circuit extend to the two sides of the ceramic laminated plate. The heating circuit is arranged between the upper-layer ceramic laminated plate and the lower-layer ceramic laminated plate, voltage is applied to the heating circuit, flowing current is generated, electric energy is converted into heat energy, the heating circuit generates heat, and the heat is transmitted outwards through the upper-layer ceramic laminated plate and the lower-layer ceramic laminated plate. And enabling the surface of the ceramic laminated plate to reach a preset temperature.

Description

Technical Field

[0001] This utility model relates to the field of ceramic heating technology, and more specifically to the field of silicon nitride ceramic heater technology. Background Technology

[0002] Silicon nitride heaters, with their high-temperature resistance and resistance to thermal cycling, are ideal for extreme environments and precision temperature control applications, especially in semiconductors, new energy, and aerospace, where they replace traditional heating elements, significantly improving equipment reliability, energy efficiency, and process precision. In the future, as manufacturing costs decrease (e.g., with optimization of gas pressure sintering processes), their applications will further expand to civilian high-temperature equipment. Meanwhile, the performance deficiencies of traditional electric heaters in various applications are becoming increasingly significant. The core problems of existing technologies in different fields are as follows:

[0003] I. Technical Bottlenecks of Industrial-Grade Heaters: Metal heating elements (stainless steel, nickel-chromium alloys) suffer from high-temperature oxidation failure, poor corrosion resistance, and electromagnetic interference (EMI), as detailed below:

[0004] High-temperature oxidation failure: The surface oxide layer thickens under operating conditions >800℃ (annual loss rate >30%), and the thermal efficiency decreases by 20%-40%; Poor corrosion resistance: Acidic / molten metal environment leads to grain boundary corrosion cracking (lifetime <2000 hours); Electromagnetic interference (EMI): The high-frequency operation of the metal wire generates strong electromagnetic radiation (noise in the 30MHz band >60dB), which interferes with precision instruments (such as semiconductor wafer temperature measurement systems).

[0005] II. Heating Technology Pain Points in Consumer Electronics: Primarily using metal / PTC ceramic plate heaters and flexible thin-film heaters, taking instant hot water dispensers, smart heated seats, and portable hand warmers as examples, existing heaters have the following shortcomings:

[0006] (1) The following problems exist with metal / PTC ceramic plate heaters:

[0007] 1) Safety hazard: The metal heating wire is in direct contact with the liquid (water dispenser), which can easily cause electric leakage (insulation resistance <10). 8 The PTC ceramic overheat protection delay (>5 seconds) does not comply with the IEC 60335-2-15 standard; the local overheating (surface temperature >120℃) may cause burns.

[0008] 2) Low energy efficiency: Traditional heating wires have slow thermal response (water dispensers require >10 seconds to dispense hot water) and high power consumption (energy efficiency ratio <85%); PTC ceramics have low power density (<5W / cm²). 2 Heated seats require multiple layers to be stacked, with a thickness greater than 15mm (affecting comfort).

[0009] 3) Design limitations: The metal heater cannot be bent and is difficult to fit the curved surface of the car seat (fitting gap >2mm leads to 30% heat loss); the surface temperature is uneven (temperature difference >±8℃), causing discomfort to users.

[0010] (2) The following problems exist with flexible thin film heaters (carbon fiber / conductive polymer):

[0011] 1) Poor temperature resistance: Long-term working temperature <150℃, polymer matrix decomposes (releasing VOCs) at high temperatures;

[0012] 2) Short lifespan: After 1000 bends, the resistance change rate is >20% (repeated adjustments of the car seat cause failure);

[0013] 3) Excessive electromagnetic radiation: Electric field strength >30V / m during high-frequency driving (exceeding the limit of GB / T 17626.3 standard).

[0014] Therefore, designing ceramic heaters that are suitable for both industrial equipment and consumer electronics is a direction that those skilled in the art should strive for. Utility Model Content

[0015] The purpose of this utility model is to provide a silicon nitride ceramic heater in order to solve the above-mentioned technical problems.

[0016] To achieve the above objectives, this utility model specifically adopts the following technical solution:

[0017] This utility model provides a silicon nitride ceramic heater, including a ceramic laminate formed by stacking multiple ceramic layers, a heating circuit with a folded shape or other shape disposed between two adjacent ceramic laminates, a connecting circuit disposed between the heating circuit and the ceramic laminate, and a plurality of through holes evenly distributed and penetrating the heating circuit and the connecting circuit.

[0018] The width of the connecting circuit is greater than the width of the heating circuit, and both ends of the connecting circuit extend to both sides of the ceramic laminate; both ends of the heating circuit extend to both sides of the ceramic laminate.

[0019] The ceramic layer can be prepared by one of the following molding methods: extrusion molding, casting molding, dry pressing molding, isostatic pressing molding, slip casting molding, etc.

[0020] In addition, the ceramic layer material is usually composed of ceramics with insulating properties such as oxide ceramics, nitride ceramics, and carbide ceramics, including ceramic materials such as alumina, aluminum nitride, and silicon nitride, with silicon nitride ceramics being preferred.

[0021] In addition, the ceramic layer can be prepared in the following way: the ceramic powder that forms the main component of the ceramic layer is preferably silicon nitride powder; rare earth oxides such as yttrium oxide, ytterbium oxide, and erbium oxide are used as sintering aids, and oxides such as magnesium oxide, aluminum oxide, and silicon dioxide are used as sintering aids. The rare earth oxides account for 1-10% of the mass of the ceramic powder, preferably 3-9%, and the oxides account for about 1-5% of the mass of the powder, preferably 2-3%. After being prepared according to the proportions, the ceramic layer is finally formed by a molding process, and the ceramic layer is stacked to obtain a ceramic laminate.

[0022] In one embodiment, the ceramic layer is rod-shaped or plate-shaped; when the ceramic layer is rod-shaped, the length of the ceramic layer is set to 50mm-120mm, the width is set to 3mm-10mm, and the thickness is set to 2mm-5mm.

[0023] Specifically, the ceramic layer can be rod-shaped, plate-shaped, etc. Specifically, when it is rod-shaped, the length of the ceramic layer is usually set to 50mm-120mm, the width of the ceramic layer is usually set to 3mm-10mm, and the thickness of the ceramic layer is usually set to 2mm-5mm.

[0024] In one embodiment, the ceramic laminate includes an upper ceramic laminate and a lower ceramic laminate, and the heating circuit is disposed between the upper ceramic laminate and the lower ceramic laminate.

[0025] Specifically, such as Figure 2 As shown, the heating circuit is located between the upper ceramic laminate and the lower ceramic laminate. By applying voltage to the heating circuit, a flowing current is generated, which converts electrical energy into heat energy. The heating circuit generates heat, and the heat is transferred outward through the upper and lower ceramic laminates, so that the surface of the ceramic laminate reaches the predetermined temperature, thereby realizing the heating and ignition functions of the heater.

[0026] The heating circuit is mainly composed of tungsten, molybdenum, tantalum, and their carbides, silicides, nitrides, etc., and may also include other high-temperature resistant alloys with good electrical conductivity, such as tungsten-nickel alloys and graphene composite metals. When the ceramic layer is preferably a silicon nitride substrate, the main component of the heating circuit can preferably be tungsten or tungsten carbide. In this case, the heating circuit and the ceramic layer have similar coefficients of thermal expansion and sintering temperatures, resulting in better co-firing compatibility.

[0027] The particle size of the heating circuit is typically selected from 0.5μm to 2μm, preferably from 1μm to 1.5μm. Using a small particle size in the heating circuit can increase the density after sintering, reduce the erosion of the internal circuit layer by external air, and at the same time, the higher density increases the resistance value, thereby increasing the heating efficiency of the heating circuit.

[0028] In one embodiment, the heating circuit includes a heating portion as the main heating area and a lead portion, wherein the circuit width of the lead portion is greater than the circuit width of the heating portion; it also includes a plurality of first through holes, which are evenly distributed on the lead portion; the rear end of the lead portion extends to both sides of the ceramic laminate.

[0029] like Figure 3 As shown, specifically, the heating circuit can be divided into a heating part and a lead part. When energized, the main heating area is concentrated in the heating part. The lead part has a wider circuit than the heating part and extends to both sides of the ceramic pressure plate. The lead part overlaps with the lead circuit. Since the resistance of the lead circuit is much smaller than that of the lead part, when energized, the main heating area is concentrated in the heating part at the tip of the heater.

[0030] To prevent mismatch between the heating slurry and the ceramic laminate during sintering, which could lead to heater cracking, uniformly distributed through holes are provided on the lead wire section. These through holes increase the bonding area between the upper and lower ceramic laminates, thereby increasing the bonding strength between them during sintering and preventing heater cracking.

[0031] In one embodiment, the heating element is shaped as a folded structure, a strip structure, or a spiral structure. The line width of the heating element is set to 100μm-300μm, and the line thickness of the heating element can be set to 5μm-25μm. Chamfers are usually required at the corners of the circuit, and the chamfer radius is usually set to 100μm-200μm. The heating element has chamfers at the corners, and the chamfer radius is usually set to 100μm-200μm.

[0032] like Figure 3 As shown, the structure of the heating part can include a folded structure, a strip structure, a spiral structure, etc. The line width can be set to 100μm-300μm, preferably 150μm-250μm, and the line thickness can be set to 5μm-25μm, preferably 10μm-20μm. At the same time, in order to prevent cracking caused by stress concentration, chamfers are usually required at the corners of the circuit, and the chamfer radius is usually set to 100-200μm.

[0033] In one embodiment, the lead wire has a line width of 300μm-600μm and a line thickness of 5μm-25μm. The heating element has a chamfer at the corner, and the chamfer radius is usually set to 100μm-200μm.

[0034] Specifically, the line width of the lead portion can be set to 300μm-600μm, preferably 400μm-500μm, and the line thickness can be set to 5μm-25μm, preferably 10μm-20μm. At the same time, in order to prevent cracking caused by stress concentration, chamfers are usually required at the corners of the circuit, and the chamfer radius is usually set to 100μm-200μm.

[0035] In one embodiment, the connection circuit is disposed between the heating circuit and the upper ceramic laminate, and further includes a plurality of second through holes, all of which are distributed on the connection circuit, and the positions and sizes of the plurality of second through holes correspond one-to-one with the first through holes.

[0036] Specifically, such as Figure 3 and Figure 4 As shown, in order to prevent mismatch between the heating slurry and the ceramic laminate during sintering, the connecting circuit is provided with uniformly distributed second through holes, the position and size of which correspond one-to-one with the first through holes in the lead wire section, ultimately increasing the contact area between the upper ceramic laminate and the lower ceramic laminate and reducing the possibility of cracking after sintering.

[0037] In one embodiment, the connection circuit includes a lead circuit and an electrode circuit. The lead circuit is disposed between the heating circuit and the electrode circuit. The lead circuit overlaps with the lead portion of the heating circuit and has the same length. The rear end of the lead circuit extends to both sides of the heater. The lead circuit, as a conductor, is responsible for transmitting the current from the electrode circuit to the heating portion of the heating circuit.

[0038] like Figure 3 As shown, more specifically, the connection circuit can be divided into a lead circuit and an electrode circuit. The lead circuit is located between the heating circuit and the electrode circuit, overlapping with the lead portion of the heating circuit, having the same length, and extending to both sides of the heater at its rear end.

[0039] In one embodiment, the structure of the lead circuit is the same as that of the lead portion, the lead circuit covers the lead portion, the line width of the lead circuit is wider than that of the lead portion, and chamfers are required at the corners of the lead circuit.

[0040] Among them, such as Figure 3 As shown, the structure of the lead circuit is the same as that of the lead section and covers the lead section. The line width is usually wider than that of the lead section, typically set to 310-610μm, preferably 410μm-510μm. At the same time, in order to prevent cracking caused by stress concentration, chamfers are usually required at the corners of the circuit, and the chamfer radius is usually set to 100-200μm.

[0041] The lead circuit is mainly composed of tungsten, molybdenum, tantalum, and their carbides, silicides, and nitrides. It may also include other high-temperature resistant alloys with good electrical conductivity, such as tungsten-nickel alloys and graphene composite metals. When the ceramic laminate is preferably a silicon nitride substrate, the main component of the lead circuit can preferably be tungsten or tungsten carbide. In this case, the lead circuit and the ceramic laminate have similar coefficients of thermal expansion and sintering temperatures, resulting in better co-firing compatibility.

[0042] The lead circuit has a larger average particle size than the heating circuit, typically 2-15 μm, preferably 5 μm-10 μm. This larger particle size effectively reduces grain boundary formation during sintering, resulting in better conductivity, reduced heating in the lead circuit, and improved heating efficiency. Simultaneously, the larger particle size allows smaller particles to be embedded within the lead circuit, improving the connection stability between the connection circuit and the heating circuit, and reducing the probability of short circuits caused by repeated expansion and contraction of the heater.

[0043] like Figure 3 and Figure 4 As shown, the electrode circuit is positioned between the lead circuit and the upper ceramic laminate, partially overlapping the lead circuit. The overlap length is set to 5-10 mm, and the two parts have the same width. To prevent cracking caused by stress concentration, chamfers are typically provided at the corners of the circuit, with a chamfer radius usually set to 100-200 μm.

[0044] The electrode circuit has similar components to the lead circuit, but compared to the lead circuit, the electrode circuit has a smaller average particle size. Specifically, the particle size is selected to be between 0.5μm and 2μm, and more preferably between 0.5μm and 1μm. The electrode circuit with a small particle size has a higher density after sintering, which reduces the porosity of the circuit layer and can effectively prevent external air from eroding the internal circuit, thereby preventing circuit disconnection and improving the stability and durability of the heater.

[0045] The beneficial effects of this utility model are as follows:

[0046] 1. This utility model has a reasonable design. The heating circuit is set between the upper ceramic laminate and the lower ceramic laminate. By applying voltage to the heating circuit, a flowing current is generated, which converts electrical energy into heat energy. The heating circuit generates heat, and the heat is transferred outward through the upper and lower ceramic laminates, so that the surface of the ceramic laminate reaches the predetermined temperature, thereby realizing the heating and ignition functions of the heater.

[0047] 2. To prevent mismatch between the heating slurry and the ceramic laminate during sintering, which could lead to heater cracking, uniformly distributed through holes are provided on the lead wire section. These through holes increase the bonding area between the upper and lower ceramic laminates, thereby increasing the bonding strength between them during sintering and preventing heater cracking.

[0048] 3. Silicon nitride heaters adopt a fully encapsulated circuit structure, which has good biocompatibility and safety reliability; silicon nitride heaters are manufactured using a high-efficiency sintering process, which has the advantages of low cost per piece and controllable cost; silicon nitride heaters can work for a long time at a high temperature of 1300℃, which has the advantage of high temperature resistance; therefore, silicon nitride heaters are widely used in gas stoves, vehicle heating devices, automotive engine glow plugs, fuel preheating, water dispenser heating pipes and other fields due to their safety reliability, cost controllability and high temperature resistance. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0050] Figure 1 This is an overall schematic diagram of a silicon nitride ceramic heater according to this utility model;

[0051] Figure 2 yes Figure 1 Cross-sectional view at point A-A';

[0052] Figure 3 This is a diagram showing the disassembly of the heater;

[0053] Figure 4 yes Figure 1 Cross-sectional view at point B-B';

[0054] Figure labels: 1-Ceramic laminate, 2-Heating circuit, 3-Connecting circuit, 4-Through hole;

[0055] 11 - Upper ceramic laminate, 12 - Lower ceramic laminate;

[0056] 21-Heating part, 22-Leading part;

[0057] 31 - Lead circuit, 32 - Electrode circuit. Detailed Implementation

[0058] To make the technical problems, technical solutions, and technical effects of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0059] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0060] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0061] In the description of the embodiments of this utility model, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the utility model product is usually placed when in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0062] Example 1

[0063] like Figures 1 to 4 As shown, this embodiment provides a silicon nitride ceramic heater, including a ceramic laminate plate 1 formed by stacking multiple ceramic layers, a heating circuit 2 with a folded shape disposed between two adjacent ceramic layers, a connecting circuit 3 disposed between the heating circuit 2 and the ceramic laminate plate, and a plurality of through holes 4 evenly distributed and passing through the heating circuit 2 and the connecting circuit 3. The ceramic layer is made of silicon nitride.

[0064] The width of the connecting circuit 3 is greater than the width of the heating circuit 2, and both ends of the connecting circuit 3 extend to both sides of the ceramic stacked plate 1; both ends of the heating circuit 2 extend to both sides of the ceramic stacked plate 1.

[0065] The ceramic layer can be prepared by one of the following molding methods: extrusion molding, casting molding, dry pressing molding, isostatic pressing molding, slip casting molding, etc.

[0066] In addition, the ceramic layer material is usually composed of ceramics with insulating properties such as oxide ceramics, nitride ceramics, and carbide ceramics, including ceramic materials such as alumina, aluminum nitride, and silicon nitride, with silicon nitride ceramics being preferred.

[0067] In addition, the ceramic layer can be prepared by the following method: the ceramic powder, which is the main component of the ceramic layer formula, is preferably silicon nitride powder; rare earth oxides such as yttrium oxide, ytterbium oxide, and erbium oxide are used as sintering aids, and oxides such as magnesium oxide, aluminum oxide, and silicon dioxide are used as sintering aids. The rare earth oxides account for 1-10% of the mass of the ceramic powder, preferably 3-9%, and the oxides account for about 1-5% of the mass of the powder, preferably 2-3%. After being prepared according to the proportions, the ceramic layer is finally formed by a molding process. The ceramic layer is then stacked to obtain a ceramic laminate 1.

[0068] Example 2

[0069] This embodiment is a further optimization based on Embodiment 1, specifically:

[0070] The ceramic layer is rod-shaped or plate-shaped; when the ceramic layer is rod-shaped, the length of the ceramic layer is set to 50mm-120mm, the width is set to 3mm-10mm, and the thickness is set to 2mm-5mm.

[0071] Specifically, the ceramic layer can be rod-shaped, plate-shaped, etc. Specifically, when it is rod-shaped, the length of the ceramic layer is usually set to 50mm-120mm, the width of the ceramic layer is usually set to 3mm-10mm, and the thickness of the ceramic layer is usually set to 2mm-5mm.

[0072] Example 3

[0073] This embodiment is a further optimization based on Embodiment 1 or Embodiment 2, specifically:

[0074] The ceramic laminate 1 includes an upper ceramic laminate 11 and a lower ceramic laminate 12, and the heating circuit 2 is disposed between the upper ceramic laminate 11 and the lower ceramic laminate 12.

[0075] Specifically, such as Figure 2 As shown, the heating circuit 2 is disposed between the upper ceramic laminate 11 and the lower ceramic laminate 12. By applying voltage to the heating circuit 2, a flowing current is generated, which converts electrical energy into heat energy. The heating circuit 2 generates heat, and the heat is transferred outward through the upper ceramic laminate 11 and the lower ceramic laminate 12, so that the surface of the ceramic laminate 1 reaches the predetermined temperature, thereby realizing the heating and ignition functions of the heater.

[0076] The heating circuit 2 is mainly composed of tungsten, molybdenum, tantalum, and their carbides, silicides, nitrides, etc., and may also include other high-temperature resistant alloys with good electrical conductivity, such as tungsten-nickel alloys and graphene composite metals. When the ceramic layer is preferably a silicon nitride substrate, the main component of the heating circuit 2 can preferably be tungsten or tungsten carbide. In this case, the heating circuit 2 and the ceramic layer have similar coefficients of thermal expansion and sintering temperatures, resulting in better co-firing compatibility.

[0077] The particle size of the heating circuit 2 is typically selected from 0.5μm to 2μm, preferably from 1μm to 1.5μm. Using a small particle size in the heating circuit 2 can increase the density after sintering, reduce the erosion of the internal circuit layer by external air, and at the same time, the higher density increases the resistance value, thereby increasing the heating efficiency of the heating circuit 2.

[0078] Tungsten carbide powder with a particle size of 0.5μm-2μm, preferably between 1-1.5μm, is selected. A single or multiple solvent can be used depending on the requirements. Solvents can be organic or water-based, including deionized water, ethanol, isopropanol, xylene, etc. Surfactants compatible with the solvent, such as PVP and BYK-11, are selected. Binders, including PVB and PVA, can be selected as needed. The raw material is prepared according to the following proportions: tungsten carbide powder: 40wt%-60wt%; solvent: 10wt%-50wt%; dispersant: 0.5wt%-2wt%; binder: 5wt%-20wt%; plasticizer: 1wt%-10wt%. The tungsten carbide powder, solvent, and dispersant are initially mixed to form a paste, which is then dispersed using a three-roll mill. Binder and plasticizer are added according to the required viscosity. Finally, a tungsten carbide paste for printing is prepared.

[0079] Example 4

[0080] This embodiment is a further optimization based on embodiment 3, specifically:

[0081] The heating circuit 2 includes a heating part 21, which is the main heating area, and a lead part 22. The circuit width of the lead part 22 is greater than the circuit width of the heating part 21. It also includes a plurality of first through holes, which are evenly distributed on the lead part 22.

[0082] The rear end of the lead portion 22 extends to both sides of the ceramic laminate 1, and the lead portion 22 overlaps with the lead circuit 31. The resistance of the lead circuit 31 is less than the resistance of the lead portion 22.

[0083] like Figure 3As shown, specifically, the heating circuit 2 can be divided into a heating part 21 and a lead wire part 22. When energized, the main heating area is concentrated in the heating part 21. The lead wire part 22 has a wider circuit than the heating part 21 and extends to both sides of the ceramic pressure plate. The lead wire part 22 overlaps with the lead wire circuit 31. Since the resistance of the lead wire circuit 31 is much smaller than the resistance of the lead wire part 22, when energized, the main heating area is concentrated in the heating part 21 at the tip of the heater.

[0084] To prevent mismatch between the heating slurry and the ceramic laminate 1 during sintering, which could cause the heater to crack, uniformly distributed through holes 4 are provided on the lead wire portion 22. By providing through holes 4, the bonding area between the upper ceramic laminate 11 and the lower ceramic laminate 12 is increased, thereby increasing the bonding force between the upper ceramic laminate 11 and the lower ceramic laminate 12 during sintering and preventing the heater from cracking.

[0085] Example 5

[0086] This embodiment is a further optimization based on embodiment 3, specifically:

[0087] The heating element 21 has a shape that is one of a folded structure, a strip structure, or a spiral structure. The line width of the heating element 21 is set to 100μm-300μm, and the line thickness of the heating element 21 can be set to 5μm-25μm. Chamfers are usually required at the corners of the circuit, and the chamfer radius is usually set to 100μm-200μm.

[0088] like Figure 3 As shown, the structure of the heating part 21 may include a folded structure, a strip structure, a spiral structure, etc. The line width can be set to 100μm-300μm, preferably 150μm-250μm, and the line thickness can be set to 5μm-25μm, preferably 10μm-20μm. At the same time, in order to prevent cracking caused by stress concentration, chamfers are usually required at the corners of the circuit, and the chamfer radius is usually set to 100-200μm.

[0089] Example 6

[0090] This embodiment is a further optimization based on embodiment 5, specifically:

[0091] The lead wire portion 22 has a line width of 300μm-600μm and a line thickness of 5μm-25μm. The heating portion 21 has a chamfer at the corner, and the chamfer radius is usually set to 100μm-200μm.

[0092] Specifically, the line width of the lead portion 22 can be set to 300μm-600μm, preferably 400μm-500μm, and the line thickness can be set to 5μm-25μm, preferably 10μm-20μm. At the same time, in order to prevent cracking caused by stress concentration, chamfers are usually required at the corners of the circuit, and the chamfer radius is usually set to 100μm-200μm.

[0093] The connecting circuit 3 is located between the heating circuit 2 and the upper ceramic laminate 11, and also includes multiple second through holes. The multiple second through holes are distributed on the connecting circuit 3, and the positions and sizes of the multiple second through holes correspond one-to-one with the first through holes.

[0094] Specifically, such as Figure 3 and Figure 4 As shown, in order to prevent mismatch between the heating slurry and the ceramic laminate during the sintering process, the connecting circuit 3 is provided with uniformly distributed second through holes, the position and size of which correspond one-to-one with the first through holes of the lead wire part 22, ultimately increasing the contact area between the upper ceramic laminate 11 and the lower ceramic laminate 12 and reducing the possibility of cracking after sintering.

[0095] The connecting circuit 3 includes a lead circuit 31 and an electrode circuit 32. The lead circuit 31 is disposed between the heating circuit 2 and the electrode circuit 32. The lead circuit 31 overlaps with the lead portion 22 of the heating circuit 2 and has the same length. The rear end of the lead circuit 31 extends to both sides of the heater. The lead circuit 31, as a conductor, is responsible for transmitting the current from the electrode circuit 32 to the heating portion 21 of the heating circuit 2.

[0096] like Figure 3 As shown, more specifically, the connecting circuit 3 can be divided into a lead circuit 31 and an electrode circuit 32. The lead circuit 31 is disposed between the heating circuit 2 and the electrode circuit 32, overlaps with the lead portion 22 of the heating circuit 2, has the same length, and extends to both sides of the heater at its rear end.

[0097] The structure of the lead circuit 31 is the same as that of the lead part 22. The lead circuit 31 covers the lead part 22. The line width of the lead circuit 31 is wider than that of the lead part 22. Chamfers need to be set at the corners of the lead circuit 31.

[0098] Among them, such as Figure 3 As shown, the structure of the lead circuit 31 is the same as that of the lead portion 22, and it covers the lead portion 22. The line width is usually wider than that of the lead portion 22, typically set to 310-610μm, preferably 410μm-510μm. Meanwhile, to prevent cracking caused by stress concentration, chamfers are usually required at the corners of the circuit, with a chamfer radius typically set to 100-200μm.

[0099] The lead circuit 31 is mainly composed of tungsten, molybdenum, tantalum, and their carbides, silicides, and nitrides. It may also include other high-temperature resistant alloys with good electrical conductivity, such as tungsten-nickel alloys and graphene composite metals. When the ceramic laminate 1 is preferably a silicon nitride substrate, the main component of the lead circuit 31 can preferably be tungsten or tungsten carbide. In this case, the lead circuit 31 and the ceramic laminate 1 have similar coefficients of thermal expansion and sintering temperatures, resulting in better co-firing compatibility.

[0100] The lead circuit 31 has a larger average particle size than the heating circuit 2, typically 2-15 μm, preferably 5 μm-10 μm. The larger particle size effectively reduces grain boundary formation in the lead circuit 31 during sintering, resulting in better conductivity, reduced heating in the lead circuit 31, and improved heating efficiency. Simultaneously, the larger particle size allows smaller particles from the heating circuit 2 to be embedded in the lead circuit 31, improving the connection stability between the connection circuit 3 and the heating circuit 2 and reducing the probability of short circuits caused by repeated expansion and contraction of the heater.

[0101] like Figure 3 and Figure 4 As shown, the electrode circuit 32 is disposed between the lead circuit 31 and the upper ceramic laminate 11, and partially overlaps with the lead circuit 31. The length of the overlapping part is set to 5-10 mm, and they have the same width. In order to prevent cracking caused by stress concentration, chamfers are usually required at the corners of the circuit, and the chamfer radius is usually set to 100-200 μm.

[0102] The electrode circuit 32 has a similar composition to the lead circuit 31, but compared to the lead circuit 31, the electrode circuit 32 has a smaller average particle size than the lead circuit 31. Specifically, the particle size is selected to be between 0.5μm and 2μm, and more preferably, the particle size is between 0.5μm and 1μm. The electrode circuit 32 with a small particle size has a higher density after sintering, which reduces the porosity of the circuit layer and can effectively prevent external air from eroding the internal circuit, thereby preventing circuit disconnection and improving the stability and durability of the heater.

Claims

1. A silicon nitride ceramic heater, characterized in that, It includes a ceramic laminate (1) formed by stacking multiple ceramic layers, a heating circuit (2) with a folded shape disposed between two adjacent ceramic layers, a connecting circuit (3) disposed between the heating circuit (2) and the ceramic laminate, and a plurality of through holes (4) evenly distributed and penetrating the heating circuit (2) and the connecting circuit (3); the width of the connecting circuit (3) is greater than the width of the heating circuit (2), and both ends of the connecting circuit (3) extend to both sides of the ceramic laminate (1); both ends of the heating circuit (2) extend to both sides of the ceramic laminate (1).

2. A silicon nitride ceramic heater according to claim 1, characterized in that, The ceramic layer is rod-shaped or plate-shaped; when the ceramic layer is rod-shaped, the length of the ceramic layer is set to 50mm-120mm, the width is set to 3mm-10mm, and the thickness is set to 2mm-5mm.

3. A silicon nitride ceramic heater according to claim 1, characterized in that, The ceramic laminate (1) includes an upper ceramic laminate (11) and a lower ceramic laminate (12), and the heating circuit (2) is disposed between the upper ceramic laminate (11) and the lower ceramic laminate (12).

4. A silicon nitride ceramic heater according to claim 3, characterized in that, The heating circuit (2) includes a heating part (21) as the main heating area and a lead part (22). The circuit width of the lead part (22) is greater than the circuit width of the heating part (21). It also includes a plurality of first through holes, which are evenly distributed on the lead part (22). The rear end of the lead part (22) extends to both sides of the ceramic laminate (1).

5. A silicon nitride ceramic heater according to claim 4, characterized in that, The heating element (21) has a shape that is one of a folded structure, a strip structure or a spiral structure. The line width of the heating element (21) is set to 100μm-300μm, and the line thickness of the heating element (21) is set to 5μm-25μm. A chamfer needs to be set at the corner of the circuit. The heating element (21) has a chamfer at the corner, and the chamfer radius is set to 100μm-200μm.

6. A silicon nitride ceramic heater according to claim 4, characterized in that, The lead wire portion (22) has a line width of 300μm-600μm and a line thickness of 5μm-25μm. The heating portion (21) has a chamfer at the corner with a chamfer radius of 100μm-200μm.

7. A silicon nitride ceramic heater according to claim 4, characterized in that, The connection circuit (3) is disposed between the heating circuit (2) and the upper ceramic stack plate (11), and also includes a plurality of second through holes. The plurality of second through holes are distributed on the connection circuit (3), and the positions and sizes of the plurality of second through holes correspond one-to-one with the first through holes.

8. A silicon nitride ceramic heater according to claim 7, characterized in that, The connection circuit (3) includes a lead circuit (31) and an electrode circuit (32). The lead circuit (31) is disposed between the heating circuit (2) and the electrode circuit (32). The lead circuit (31) overlaps with the lead portion (22) of the heating circuit (2) and has the same length. The rear end of the lead circuit (31) extends to both sides of the heater. The lead circuit (31) serves as a conductor and is responsible for transmitting the current from the electrode circuit (32) to the heating portion (21) of the heating circuit (2).

9. A silicon nitride ceramic heater according to claim 8, characterized in that, The structure of the lead circuit (31) is the same as that of the lead part (22). The lead circuit (31) covers the lead part (22). The line width of the lead circuit (31) is wider than that of the lead part (22). Chamfers need to be provided at the corners of the lead circuit (31).

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