Metallization treatment method for heating element, heating element and aerosol generating device

Abstract

The present application relates to a metallization treatment method for a heating element, a heating element, and an aerosol generating device, wherein the method includes the following steps: pre-fixing the connection portion of a conductive ceramic substrate and a metal electrode by means of a welding slurry, wherein the alloy components in the welding slurry include at least one of a silver-copper-titanium alloy, a silver-copper-titanium-indium alloy, and a silver-palladium-titanium alloy; drying the pre-fixed conductive ceramic substrate and the metal electrode, sintering them in stages, and then cooling them to obtain a heating element. The metallization treatment method for a heating element provided in the present application can improve the welding strength between the metal electrode and the conductive ceramic substrate, improve the stability of use, and can effectively control the resistance change of the heating element during heating and use; at the same time, this conductive ceramic surface metallization process has low cost, is easy to operate, and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramics, and in particular to a metallization treatment method for a heating element, a heating element, and an aerosol generating device. Background Art

[0002] At present, with the rapid development of heat-not-burn aerosol generating devices, their heating elements have become core components, determining the overall design and performance quality level of the aerosol generating devices. Ceramic heating elements have gradually replaced old-fashioned heating resistance wires due to their advantages such as anti-oxidation, high temperature resistance and long life. At present, heating elements are usually formed by printing resistance paste on a ceramic substrate to form a heating track. When conductive ceramics are used as heating elements, the welding strength between the conductive ceramic substrate material and the electrode is low, the welding contact resistance is large, and during the cyclic heating process, the electrode solder joints are easily loosened and fall off due to thermal stress, which easily causes the resistance to increase. Therefore, conductive ceramics need to be metallized before welding. The commonly used ceramic surface metallization method is to use chemical vapor deposition (CVD) to coat the ceramic surface. However, this method has a long process, high cost, and relatively stringent requirements on the ceramic surface state. At the same time, the CVD coating thickness is relatively thin, which is not suitable for subsequent lead welding. The leads and solder joints are also easily loosened and fall off due to thermal stress. Summary of the Invention

[0003] The embodiments of the present invention provide a metallization treatment method for a heating element, a heating element, and an aerosol generating device, which can improve the welding strength between the electrode and the conductive ceramic substrate, improve the stability of use, and effectively control the resistance change of the heating element during heating.

[0004] In a first aspect, the present application provides a method for metallizing a heating element, comprising the following steps:

[0005] Pre-fixing the connecting portion of the conductive ceramic substrate and the metal electrode by means of a welding slurry, wherein the alloy component in the welding slurry comprises at least one of a silver-copper-titanium alloy, a silver-copper-titanium-indium alloy, and a silver-palladium-titanium alloy;

[0006] The pre-fixed conductive ceramic substrate and the metal electrode are dried, sintered in stages at elevated temperatures, and then cooled to obtain a heating element.

[0007] In combination with the first aspect, in a feasible implementation manner, the conductive ceramic substrate includes a first connection portion protruding outward from both sides of the conductive ceramic substrate, and the surface of the first connection portion is coated with the solder paste.

[0008] In combination with the first aspect, in a feasible embodiment, the metal electrode is a metal clip, which includes two clips and a base connecting the two clips. The two clips are clamped on both sides of the first connecting part, and a first through hole is respectively opened on the two clips. At least part of the welding slurry overflows to the surface of the clip through the first through hole.

[0009] In combination with the first aspect, in a feasible embodiment, the metal electrode is a metal sheet, the metal sheet is arranged on the surface of the first connecting part, and the metal sheet is provided with a second through hole passing through the metal sheet, and at least part of the welding slurry overflows to the surface of the metal sheet through the second through hole.

[0010] In combination with the first aspect, in a feasible embodiment, the conductive ceramic substrate includes a second connecting portion located at the bottom of the conductive ceramic substrate, the metal electrode is a metal seat, the metal seat is provided with a receiving groove, and the second connecting portion is received in the receiving groove.

[0011] In combination with the first aspect, in a feasible embodiment, the receiving groove includes a first groove section located at the bottom of the receiving groove and a second groove section located at the top of the receiving groove, the second connecting portion is clamped in the first groove section, and a gap is left between the second connecting portion and the second groove section, the gap is filled with the welding slurry, and the filling height of the welding slurry is at least 1 / 2 of the height of the second groove section.

[0012] In combination with the first aspect, in a feasible implementation manner, the first trough section and the second trough section are connected via a side guide surface with a slope.

[0013] In combination with the first aspect, in a feasible implementation manner, the coating thickness of the welding slurry is 0.1 mm to 0.3 mm.

[0014] In conjunction with the first aspect, in a feasible implementation manner, the method satisfies at least one of the following features a to d:

[0015] a. The conductive ceramic matrix material comprises at least one of silicon carbide, silicon nitride, aluminum oxide, silicon oxide, titanium diboride, titanium carbide and zirconium diboride;

[0016] b. The thickness of the conductive ceramic substrate is 0.3mm to 2mm;

[0017] c. The resistivity of the conductive ceramic substrate is ≥1.0×10 -6 Ω·m;

[0018] d. The metal electrode is made of copper or silver, and at least one of a silver film, a gold film or a nickel film is formed on the surface of the metal electrode.

[0019] In conjunction with the first aspect, in a feasible implementation manner, the method satisfies at least one of the following features a-b:

[0020] a. The viscosity of the welding slurry is 100Pa·s~180Pa·s;

[0021] b. The average particle size of the alloy component in the solder paste is 10 μm to 50 μm.

[0022] In conjunction with the first aspect, in a feasible implementation manner, the method satisfies at least one of the following features a to c:

[0023] a. The drying temperature is 150 ℃ ~ 250 ℃;

[0024] b. The drying time is 0.5h to 2h;

[0025] c. The drying method is air drying.

[0026] In conjunction with the first aspect, in a feasible implementation manner, the method satisfies at least one of the following features a to d:

[0027] a. The heating rate of the staged sintering is 8°C / min to 12°C / min;

[0028] b. The staged temperature sintering is carried out in a vacuum environment, and the vacuum degree of the vacuum environment is ≤1.0×10 - 2 Pa;

[0029] c. The temperature of the staged sintering is room temperature to 860°C;

[0030] d. The staged temperature sintering includes three stages of temperature rising treatment, wherein the first stage is to heat up to 290℃~320℃ and keep warm for 13min~18min; the second stage is to heat up to 720℃~750℃ and keep warm for 13min~18min; the third stage is to heat up to 830℃~860℃ and keep warm for 8min~12min.

[0031] In a second aspect, the present application provides a heating element, which is manufactured using the metallization treatment method described in the first aspect.

[0032] In a third aspect, the present application provides an aerosol generating device comprising the heating element described in the second aspect.

[0033] Compared with the existing technology, the technical solution provided by this application has at least the following beneficial effects:

[0034] The metallization treatment method for the heating element provided in the present application utilizes welding slurry to bond and pre-fix the connection part of the conductive ceramic substrate with the metal electrode, which can achieve rapid positioning, and then through drying and staged temperature rising and sintering, the welding strength between the metal electrode and the conductive ceramic substrate is improved, thereby improving the stability of the heating element. During the heating process of the heating element, the metal electrode can be prevented from loosening or falling off due to thermal stress, and the resistance change of the heating element during heating can be effectively controlled. At the same time, this conductive ceramic surface metallization process has low cost, simple operation, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 1 is a schematic flow chart of a metallization treatment method for a heating element provided in an embodiment of the present application;

[0037] Figure 2 This is a schematic structural diagram of a conductive ceramic substrate provided in one embodiment of the present application;

[0038] Figure 3a This is a side view of a heating element provided by an embodiment of the present application;

[0039] Figure 3b This is a schematic structural diagram of a heating element provided in one embodiment of the present application;

[0040] Figure 3c This is a schematic structural diagram of a metal electrode in a heating element provided in one embodiment of the present application;

[0041] Figure 4a is a side view of a heating element provided by another embodiment of the present application;

[0042] Figure 4b is a schematic structural diagram of a heating element provided in another embodiment of the present application;

[0043] Figure 5a is a side view of a heating element provided by another embodiment of the present application;

[0044] Figure 5b is a schematic structural diagram of a heating element provided in another embodiment of the present application;

[0045] Figure 5c This is a schematic structural diagram of a metal electrode in a heating element provided in another embodiment of the present application;

[0046] Figure 6a 、 Figure 6b Schematic diagrams of the states of the electrodes of the heating element prepared in comparative example 1 before and after the cycle. DETAILED DESCRIPTION

[0047] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0048] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0049] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "an", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0050] In addition, the features, operations, or characteristics described in the specification may be combined in any appropriate manner to form various embodiments. Furthermore, the steps or actions in the method description may be reordered or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various sequences in the specification and drawings are provided solely for the purpose of clearly describing a particular embodiment and are not intended to be mandatory, unless otherwise specified.

[0051] The serial numbers assigned to components herein, such as "first," "second," etc., are used solely to distinguish the objects being described and do not convey any sequential or technical meaning. References to "connected" and "coupled" in this application include both direct and indirect connections unless otherwise specified.

[0052] The term "aerosol generating device" as used herein refers to a device that generates aerosol by heating an aerosol generating article to a temperature lower than its combustion temperature, thereby avoiding the generation of toxic and harmful substances due to the combustion of the aerosol generating article.

[0053] Figure 1 Schematic diagram of the process of metallization treatment of heating element provided by the embodiment of the present application. Figure 1 As shown,

[0054] Step S10, pre-fixing the connecting portion of the conductive ceramic substrate and the metal electrode by means of a welding slurry, wherein the alloy component in the welding slurry includes at least one of a silver-copper-titanium alloy, a silver-copper-titanium-indium alloy, and a silver-palladium-titanium alloy;

[0055] In step S20 , the pre-fixed conductive ceramic substrate and the metal electrode are dried, sintered in stages at elevated temperatures, and then cooled to obtain a heating element.

[0056] The metallization treatment method for the heating element provided in the present application utilizes welding slurry to bond and pre-fix the connection part of the conductive ceramic substrate with the metal electrode, which can achieve rapid positioning, and then through drying and staged temperature rising and sintering, the welding strength between the metal electrode and the conductive ceramic substrate is improved, thereby improving the stability of the heating element. During the heating process of the heating element, the metal electrode can be prevented from loosening or falling off due to thermal stress, and the resistance change of the heating element during heating can be effectively controlled. At the same time, this conductive ceramic surface metallization process has low cost, simple operation, and is suitable for industrial production.

[0057] The following describes this solution in detail through specific embodiments:

[0058] Before step S10, a conductive ceramic matrix is obtained by dry pressing the conductive ceramic matrix material.

[0059] The conductive ceramic matrix material includes at least one of silicon carbide, silicon nitride, aluminum oxide, silicon oxide, titanium diboride, titanium carbide, and zirconium diboride. Preferably, the conductive ceramic matrix material is a composite material of silicon carbide and titanium diboride. It should be noted that the conductive ceramic matrix material refers to a new type of material with ion conductivity and electron / hole conductivity in ceramic materials. The conductive ceramic matrix material has the characteristics of anti-oxidation, anti-corrosion, high temperature resistance and long life. The heating element made of the conductive ceramic matrix material can release heat evenly during repeated heating, avoid local overheating of the heated non-combustible product, produce irritating smells such as burnt smell, and extend the service life of the heating element.

[0060] Figure 2 is a schematic structural diagram of a conductive ceramic substrate provided in one embodiment of the present application. Figure 2 As shown, the conductive ceramic substrate 1 can be in the form of a longitudinal sheet, and the thickness of the conductive ceramic substrate 1 can be 0.3 to 2 mm, specifically 0.5 mm, 0.7 mm, 0.9 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm or 2 mm, etc., which is not limited here; the thickness of the conductive ceramic substrate 1 is preferably 1 mm.

[0061] The resistivity of the conductive ceramic substrate 1 is ≥1.0×10 -6 Ω·m, specifically 1.0×10 -6 Ω·m、1.5×10 -5 Ω·m、1.1×10 -5 Ω·m、1.2×10 -4 Ω·m, etc., are not limited here.

[0062] It should be noted that due to the thinness of the conductive ceramic substrate, the resulting thermal resistance is relatively high, and the solder joints are particularly susceptible to aging. Therefore, welding is difficult and requires higher weld strength. Furthermore, the lower the resistivity of the conductive ceramic substrate, the easier it is to weld. The conductive ceramics in this application have high resistivity, so even higher requirements are placed on weld strength and resistance to oxidation and aging.

[0063] The conductive ceramic substrate 1 includes an insert portion 11 and a connecting portion, which are integrally formed. The insert portion 11 is used to insert into the aerosol-forming substrate of an aerosol-generating device. Heat from the heating element causes the aerosol-forming substrate to form an aerosol. In this embodiment, the insert portion 11 has a V-shaped tip, which facilitates insertion of the heating element into the aerosol-forming substrate. The edges of the insert portion 11 are sharpened to further facilitate insertion into the aerosol-forming substrate.

[0064] The connecting portion includes a first connecting portion 12 and a second connecting portion 13. The first connecting portion 12 is formed by protruding outward from both sides of the conductive ceramic substrate 1; the first connecting portion 12 is used to realize the installation of the heating element in the shell of the aerosol generating device, and the first connecting portion 12 can be used to connect with the metal electrode 3. In this embodiment, the first connecting portion 12 enables the heating element to be clamped in the installation cavity of the shell of the aerosol generating device. The second connecting portion 13 is located at the bottom of the conductive ceramic substrate 1 and extends toward the bottom end. The second connecting portion 13 can be used to connect with the metal electrode 3. It should be noted that the conductive ceramic substrate 1 is obtained by dry pressing and sintering a conductive ceramic material into a mold.

[0065] Furthermore, to form a conductive loop, the conductive ceramic substrate 1 is provided with a longitudinal through-slot 14. This through-slot 14 enables the conductive ceramic substrate 1 to form a loop when energized. The two first connecting portions 12 and the two second connecting portions 13 are symmetrically arranged along the through-slot 14. The through-slot 14 is also formed by dry pressing and can be filled with an insulating material.

[0066] Before step S10, the method further includes:

[0067] Performing surface polishing on the conductive ceramic substrate 1;

[0068] The polished conductive ceramic substrate 1 is placed in a cleaning solution for ultrasonic cleaning.

[0069] It can be understood that the dirt on the surface of the conductive ceramic substrate can be removed by polishing and ultrasonic cleaning.

[0070] In a specific embodiment, the conductive ceramic substrate 1 obtained by dry pressing is polished using an alumina polishing liquid. The average particle size of the metal particles in the alumina polishing liquid is 1 μm to 3 μm, and can specifically be 1 μm, 1.5 μm, 2 μm, 2.2 μm, 2.5 μm, 2.8 μm, or 3 μm, etc., without limitation herein.

[0071] Ultrasonic cleaning uses a cleaning fluid that is at least 99% acetone or ethanol by weight, effectively removing dirt from the surface of the conductive ceramic substrate. Ultrasonic cleaning lasts for 5 to 15 minutes, effectively removing dirt.

[0072] Step S10: pre-fixing the connecting portion of the conductive ceramic substrate and the metal electrode by means of a welding slurry, wherein the alloy component in the welding slurry comprises at least one of a silver-copper-titanium alloy, a silver-copper-titanium-indium alloy, and a silver-palladium-titanium alloy.

[0073] The alloy component in the welding slurry can be at least one of silver-copper-titanium alloy, silver-copper-titanium-indium alloy, and silver-palladium-titanium alloy. It should be noted that the wettability of the welding slurry can be adjusted by adjusting the mass ratio of silver and copper. The indium metal in silver-copper-titanium-indium helps to lower the melting point of the alloy component, which is beneficial to improve the welding stability of the electrode and the conductive ceramic. For example, the silver-copper-titanium alloy can be Ag-Cu-Ti2, which has a melting point of 780℃~805℃; the silver-copper-titanium alloy can also be Ag-Cu-Ti 4.5 , with a melting point of 780°C to 810°C; the silver-copper-titanium-indium alloy can also be Ag-Cu-In-Ti3, with a melting point of 540°C to 650°C. It is understandable that the melting point of the alloy components can be adjusted by adjusting the mass ratio of each element metal in the alloy.

[0074] Furthermore, the viscosity of the solder paste is between 100 Pa·s and 180 Pa·s, and can be 100 Pa·s, 110 Pa·s, 120 Pa·s, 130 Pa·s, 140 Pa·s, 160 Pa·s, or 180 Pa·s, etc., without limitation. When the viscosity of the solder paste is greater than 180 Pa·s, it is difficult to handle; and when the viscosity of the solder paste is less than 100 Pa·s, it is not conducive to the initial bonding and fixation of the metal electrode to the conductive ceramic substrate.

[0075] The average particle size of the alloy component in the welding slurry is 10 μm to 50 μm, and can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm, etc., which is not limited here.

[0076] As an optional technical solution of this application, the metal electrode is made of copper or silver, and at least one of a silver film, a gold film, or a nickel film is formed on the surface of the metal electrode. Plating the copper or silver electrode surface with a film can slow down high-temperature oxidation of the electrode and extend its service life.

[0077] Figure 3a This is a side view of a heating element provided by an embodiment of the present application. Figure 3b This is a schematic diagram of the structure of a heating element provided in one embodiment of the present application. Figure 3c Schematic diagram of the structure of the metal electrode in the heating element provided in one embodiment of the present application; Figures 3a to 3c As shown, the metal electrode 3 is a metal clip 30 , which can be a copper clip or a silver clip. The surface of the metal clip can be plated with a silver film, a gold film or a nickel film.

[0078] The metal clip 30 includes two clip bodies 301 and a base 302 connecting the two clip bodies 301 . The two clip bodies 301 are clamped on both sides of the first connecting portion 12 . The two clip bodies 301 are respectively provided with a first through hole 303 penetrating the clip bodies 301 .

[0079] In this embodiment, at least one surface of the first connecting portion 12 is coated with a welding slurry. The coating thickness of the welding slurry is 0.1mm to 0.3mm, and specifically can be 0.1mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, or 0.3mm, etc., which are not limited here. If the welding slurry is too thick, the overall thickness of the conductive ceramic substrate increases after the metal electrode is welded to the conductive ceramic substrate, which can easily affect the space for subsequent installation. If the welding slurry is too thin, the welding slurry is not easy to overflow onto the surface of the electrode, which is not conducive to improving the welding strength.

[0080] After the metal clip 30 is clamped onto the first connecting portion 12 coated with solder paste, at least a portion of the solder paste overflows through the first through-hole 303 onto the surface of the clamp body 301. After subsequent sintering, the solder paste securely connects the metal clip to the first connecting portion 12, thereby improving the weld strength. In this embodiment, by designing the metal electrode as a metal clip, the two clamp bodies 301 of the metal clip can be used to clamp the first connecting portion 12, achieving better fixation and improving connection stability.

[0081] During the soldering slurry coating process, the soldering slurry may be coated on one surface of the first connecting portion 12 or both surfaces thereof, thereby improving the soldering strength between the clip 301 and the first connecting portion 12 .

[0082] Figure 4a is a side view of a heating element provided by another embodiment of the present application. Figure 4bThis is a schematic diagram of the structure of a heating element provided by another embodiment of the present application. Figures 4a to 4b As shown, the metal electrode 3 is a metal sheet 31, which can specifically be a copper sheet or a silver sheet. The edge of the metal sheet 31 can be aligned with the edge of the connecting portion 3, or it can be misaligned. In this embodiment, the shape of the metal sheet 31 corresponds to the first connecting portion 12, and the metal sheet 31 can substantially cover the first connecting portion 12, thereby increasing the welding area and improving the welding strength. For example, when the first connecting portion 12 is rectangular, the metal sheet 31 is also rectangular.

[0083] In this embodiment, at least one surface of the first connecting portion 12 is coated with a solder paste having a coating thickness of 0.1 mm to 0.3 mm. The metal sheet 31 is provided with a second through hole 311 extending therethrough. The provision of the second through hole 311 facilitates the solder paste from the second through hole 311 to the surface of the metal sheet 31, thereby improving the welding strength. The thickness of the metal sheet 31 is 0.1 mm to 0.5 mm, and may specifically be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, or 0.5 mm, etc., without limitation herein.

[0084] Figure 5a is a side view of a heating element provided by another embodiment of the present application. Figure 5b This is a structural diagram of a heating element provided by another embodiment of the present application. Figure 5c Schematic diagram of the structure of the metal electrode in the heating element provided in another embodiment of the present application; Figures 5a to 5c As shown, the metal electrode 3 is a metal seat 32, which can be a copper seat or a silver seat. The surface of the copper seat or the silver seat can be plated with a silver film, a gold film or a nickel film.

[0085] The metal base 32 defines a receiving groove 320 , and the second connecting portion 13 of the conductive ceramic base 1 is received in the receiving groove 320 .

[0086] To facilitate quick positioning of the second connecting portion 13 within the receiving groove 320, the receiving groove 320 includes a first groove section 321 at the bottom of the receiving groove 320 and a second groove section 322 at the top of the receiving groove 320. The first groove section 321 and the second groove section 322 are connected by a sloped side guide surface 323. The design of the side guide surface 323 facilitates quick positioning of the metal electrode 3 during installation, improving assembly efficiency. Specifically, the side guide surface 323 can be a flat surface or a curved surface.

[0087] The diameter of the second slot section 322 is larger than that of the first slot section 321. The second connecting portion 13 is secured within the first slot section 321, leaving a gap between the second connecting portion 13 and the second slot section 322. This gap is filled with welding slurry, with the filling height being at least 1 / 2 of the height of the second slot section 322, and specifically 1 / 2, 2 / 3, 3 / 4, 4 / 5, 5 / 6, etc., without limitation. By controlling the filling height of the welding slurry, the welding slurry can ensure that the second connecting portion 13 and the metal seat are fully connected, thereby improving welding strength.

[0088] In actual use, the second connecting portion 13 of the conductive ceramic substrate is inserted into the receiving groove 320, and then welding slurry is injected between the second connecting portion 13 and the second groove section 322. The welding slurry initially bonds and secures the second connecting portion 13 to the metal seat 32. In this embodiment, the welding slurry filled in the gap can flow around the second connecting portion 13, thereby improving the welding strength between the metal electrode 31 and the conductive ceramic substrate 1.

[0089] In step S20 , the pre-fixed conductive ceramic substrate and the metal electrode are dried, sintered in stages at elevated temperatures, and then cooled to obtain a heating element.

[0090] The drying temperature is 150°C to 250°C, specifically 180°C, 200°C, 210°C, 220°C, 230°C, 240°C, 245°C or 250°C, etc. The drying time is 0.5h to 2h, specifically 0.5h, 0.6h, 0.7h, 0.8h, 1.0h, 1.2h, 1.5h, 1.8h or 2.0h, etc., which is not limited here.

[0091] In a specific embodiment, the drying method is forced air drying. The assembled conductive ceramic substrate can be placed on a quartz boat or a graphite boat and placed in a forced air drying oven for drying.

[0092] The dried conductive ceramic substrate and the metal electrode are subjected to stage-by-stage temperature sintering, wherein the stage-by-stage temperature sintering is carried out in a vacuum environment with a vacuum degree of ≤1.0×10 -2 Pa, specifically 1.0×10 -3 Pa, 5.0×10 -3 Pa, 7.0×10 -4 Pa, 2.0×10 -4 Pa, 1.4×10 -3 Pa, etc., are not limited here.

[0093] The temperature of the stage-by-stage sintering is from room temperature to 860°C. The temperature of the stage-by-stage sintering can be adjusted according to the solder formula. For example, the peak sintering temperature of the silver-copper-titanium solder is 860°C. Specifically, the temperature range of the peak of the stage-by-stage sintering is 650°C to 860°C. The peak sintering temperature is determined according to the choice of solder, such as 650°C, 680°C, 720°C, 750°C, 780°C, 820°C or 860°C, etc., and of course it can also be other values within the above range. The heating rate of the stage-by-stage sintering is 8°C / min to 12°C / min, and specifically it can be 8°C / min, 9°C / min, 10°C / min, 11°C / min or 12°C / min, etc., and of course it can also be other values within the above range.

[0094] Specifically, the staged sintering process involves three heating stages: the first stage involves heating to 290°C to 320°C and holding for 13 to 18 minutes; the second stage involves heating to 720°C to 750°C and holding for 13 to 18 minutes; and the third stage involves heating to 830°C to 860°C and holding for 5 to 12 minutes. This staged sintering ensures a secure weld between the conductive ceramic substrate and the metal electrode, improving weld strength.

[0095] The sintered conductive ceramic substrate is cooled to obtain a heating element. The cooling may be furnace cooling, natural cooling or rapid cooling, which is not limited here.

[0096] The following further describes the embodiments of the present invention in multiple embodiments. The embodiments of the present invention are not limited to the following specific embodiments. Within the scope of the unchanged main rights, appropriate changes can be made to the implementation.

[0097] Example 1

[0098] (1) The conductive ceramic matrix material formed by the composite of silicon carbide and titanium diboride was dry pressed to obtain a conductive ceramic matrix with a thickness of 1 mm. The resistivity of the conductive ceramic matrix was 3.0×10 -5 The conductive ceramic base includes two symmetrically arranged first connecting parts.

[0099] (2) The surface of the conductive ceramic substrate is polished with an aluminum oxide polishing liquid, and the conductive ceramic substrate after polishing is ultrasonically cleaned in an acetone solution with a mass ratio of more than 99% for 10 minutes.

[0100] (3) Applying a silver-copper-titanium alloy solder paste to the surface of the first connecting portion, and controlling the coating thickness of the solder paste to be 0.2 mm.

[0101] (4) placing copper clips on both sides of the first connecting portion, with part of the solder paste overflowing onto the surface of the copper clips;

[0102] (5) The conductive ceramic substrate and the copper clamp that have been initially fixed are placed in a blast drying oven for drying, and the temperature in the blast drying oven is controlled at 220°C for 1 hour; then they are placed in a vacuum sintering furnace and heated to 300°C at a rate of 10°C / min and kept warm for 15 minutes, then heated to 750°C and kept warm for 15 minutes, and then heated to 860°C and kept warm for 10 minutes. The conductive ceramic substrate after welding is cooled in the furnace to obtain a heating element.

[0103] Example 2

[0104] The difference from Example 1 is that the conductive ceramic matrix is obtained by dry pressing a conductive ceramic matrix material containing silicon nitride.

[0105] Example 3

[0106] Different from Example 1, a solder paste containing silver-copper-titanium-indium alloy is coated on the surface of the first connecting part; during the sintering process, the temperature is raised to 300°C at 8°C / min and kept warm for 15 minutes, then raised to 550°C and kept warm for 15 minutes, and then raised to 700°C and kept warm for 10 minutes. The conductive ceramic substrate after welding is cooled in the furnace to obtain a heating element.

[0107] Example 4

[0108] Different from Example 1, the coating thickness of the solder paste is controlled to be 0.2 mm, and the sintering peak temperature is adjusted to 820°C.

[0109] Example 5

[0110] (1) The conductive ceramic matrix material formed by the composite of silicon carbide and titanium diboride was dry pressed to obtain a conductive ceramic matrix with a thickness of 1 mm. The resistivity of the conductive ceramic matrix was 3.0×10 -5 The conductive ceramic base includes two symmetrically arranged second connecting parts.

[0111] (2) The surface of the conductive ceramic substrate is polished with an aluminum oxide polishing liquid, and the conductive ceramic substrate after polishing is ultrasonically cleaned in an acetone solution with a mass ratio of more than 99% for 10 minutes.

[0112] (3) Insert the two second connection parts of the conductive ceramic substrate into the corresponding copper seat respectively, fill the gap in the copper seat with a welding paste containing silver-copper-titanium alloy, and control the filling height of the welding paste to be 1 / 2 of the height of the second groove section of the copper seat receiving groove.

[0113] (4) The conductive ceramic substrate and the copper seat that have been preliminarily fixed are placed in a blast drying oven for drying, and the temperature in the blast drying oven is controlled at 220°C for 2 hours; then they are placed in a vacuum sintering furnace and heated to 300°C at a rate of 10°C / min and kept warm for 15 minutes, then heated to 750°C and kept warm for 15 minutes, and then heated to 860°C and kept warm for 10 minutes. The conductive ceramic substrate after welding is cooled in the furnace to obtain a heating element.

[0114] Comparative Example 1

[0115] Different from Example 1, a conventional silver paste containing glass powder is coated on the surface of the first connecting portion, and the thickness of the solder paste is controlled to be 0.2 mm.

[0116] Comparative Example 2

[0117] Different from Example 1, the coating thickness of the solder paste was controlled to be 0.05 mm, and the solder paste did not overflow onto the surface of the copper clip.

[0118] Comparative Example 3

[0119] The difference from Example 5 is that the filling height of the solder paste is controlled to be 1 / 4 of the height of the second groove section of the copper seat receiving groove.

[0120] The heating elements prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to resistance value tests and thermal cycle performance tests.

[0121] Thermal cycling performance tests are:

[0122] The heating element was heated from room temperature to 350°C within 10 seconds, kept at this temperature for 3 minutes, and then naturally cooled for 3 minutes. This was counted as one cycle. After repeating the cycle 600 times, the resistance value of the heating element was tested. The test results are shown in Table 1 below:

[0123] Table 1

[0124]

[0125]

[0126] Figures 6a to 6b Schematic diagram of the state of the electrode of the heating element prepared in Comparative Example 1 before and after the cycle; Figure 6a and Figure 6bAs shown, comparative example 1 uses traditional silver paste, and the electrode made of it cracks at the connection between the electrode and the conductive ceramic substrate after the cycle, and the electrode becomes loose. In addition, the resistance change value of the heating element is greatly improved compared with Example 1. This is because, during the cyclic heating process of the traditional silver paste, the solder joints of the electrodes are easily loosened by thermal stress, which easily causes the resistance to increase. However, Example 1 of the present application uses a welding paste containing silver-copper-titanium alloy, and the first connecting part of the 6 metal electrodes and the conductive ceramic substrate is welded into shape by welding paste, which can improve the welding strength and the stability of the electrode. Its resistance change value is only 4.1%. Example 1 can effectively control the resistance change of the heating element during heating.

[0127] The thickness of the welding slurry on the surface of the first connection part of Comparative Example 2 is only 0.05 mm. The welding slurry is too little, the welding area is reduced, the welding strength between the copper clip and the conductive ceramic substrate is reduced, and the welding point of the electrode is easily loosened by thermal stress, which easily causes the resistance to increase.

[0128] In Comparative Example 3, the filling height of the welding slurry is 1 / 4 of the height of the copper seat receiving groove. The welding slurry is filled too little, the welding strength between the copper seat and the conductive ceramic substrate decreases, and the welding point of the electrode is easily loosened by thermal stress, which easily causes the resistance to increase.

[0129] According to the test data of Examples 1 to 5, the use of welding slurry to weld and fix the conductive ceramic substrate and the metal electrode can improve the welding strength between the metal electrode and the conductive ceramic substrate, and improve the stability of the heating element. During the heating process of the heating element, the metal electrode can be prevented from loosening or falling off due to thermal stress, and the resistance change of the heating element during heating can be effectively controlled.

[0130] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for metallizing a heating element, characterized in that: The following steps are involved: Pre-fixing the connecting portion of the conductive ceramic substrate and the metal electrode by means of a welding slurry, wherein the alloy component in the welding slurry comprises at least one of a silver-copper-titanium alloy, a silver-copper-titanium-indium alloy, and a silver-palladium-titanium alloy; The pre-fixed conductive ceramic substrate and the metal electrode are dried, sintered in stages at elevated temperatures, and then cooled to obtain a heating element; The conductive ceramic substrate includes a first connecting portion protruding outward from both sides of the conductive ceramic substrate, and the surface of the first connecting portion is coated with the solder paste; The metal electrode is a metal clip, which includes two clips and a base connecting the two clips, the two clips are clamped on both sides of the first connecting portion, and the two clips are respectively provided with a first through hole, so that at least part of the welding slurry overflows onto the surface of the clip through the first through hole; or The conductive ceramic substrate includes a second connecting portion located at the bottom of the conductive ceramic substrate, the metal electrode is a metal seat, the metal seat is provided with a receiving groove, and the second connecting portion is received in the receiving groove; The receiving groove includes a first groove section located at the bottom of the receiving groove and a second groove section located at the top of the receiving groove, the second connecting portion is clamped in the first groove section, a gap is left between the second connecting portion and the second groove section, the gap is filled with the welding slurry, and the filling height of the welding slurry is at least 1 / 2 of the height of the second groove section; The first trough section and the second trough section are connected via a side guide surface with a slope.

2. The metallization treatment method according to claim 1, characterized in that: The coating thickness of the welding slurry is 0.1 mm to 0.3 mm.

3. The metallization treatment method according to claim 1, characterized in that: The method satisfies at least one of the following characteristics a to d: a. The conductive ceramic matrix material comprises at least one of silicon carbide, silicon nitride, aluminum oxide, silicon oxide, titanium diboride, titanium carbide and zirconium diboride; b. The thickness of the conductive ceramic substrate is 0.3mm to 2mm; c. The resistivity of the conductive ceramic substrate is ≥1.0×10 -6 Ω·m; d. The metal electrode is made of copper or silver, and at least one of a silver film, a gold film or a nickel film is formed on the surface of the metal electrode.

4. The metallization treatment method according to claim 1, characterized in that: The method satisfies at least one of the following characteristics a and b: a. The viscosity of the welding slurry is 100Pa·s~180Pa·s; b. The average particle size of the alloy component in the solder paste is 10 μm to 50 μm.

5. The metallization treatment method according to claim 1, characterized in that: The method satisfies at least one of the following characteristics a to c: a. The drying temperature is 150 ℃ ~ 250 ℃; b. The drying time is 0.5h to 2h; c. The drying method is air drying.

6. The metallization method according to claim 1, characterized in that: The method satisfies at least one of the following characteristics a to d: a. The heating rate of the staged sintering is 8°C / min to 12°C / min; b. The staged temperature sintering is carried out in a vacuum environment, and the vacuum degree of the vacuum environment is ≤1.0×10 -2 Pa; c. The staged sintering temperature is from room temperature to 860°C; d. The staged temperature sintering includes three stages of temperature rising treatment, wherein the first stage is to heat up to 290℃~320℃ and keep warm for 13min~18min; the second stage is to heat up to 720℃~750℃ and keep warm for 13min~18min; the third stage is to heat up to 830℃~860℃ and keep warm for 5min~12min.

7. A heating element, characterized in that: The heating element is prepared by the metallization method according to any one of claims 1 to 6, wherein the heating element comprises: A conductive ceramic substrate, the conductive ceramic substrate comprising first connecting portions protruding outward from both sides of the conductive ceramic substrate; A metal electrode is welded and fixed to the conductive ceramic substrate, wherein the metal electrode is a metal clip, and the metal clip includes two clips and a substrate connecting the two clips, wherein the two clips are clamped on both sides of the first connecting portion, and the two clips are respectively provided with a first through hole; or The heating element includes: A conductive ceramic substrate, wherein the conductive ceramic substrate comprises a second connecting portion located at a bottom of the conductive ceramic substrate; a metal electrode welded and fixed to the conductive ceramic substrate, the metal electrode being a metal seat having a receiving groove, the second connecting portion being received in the receiving groove, the receiving groove comprising a first groove section located at the bottom of the receiving groove and a second groove section located at the top of the receiving groove, the first groove section and the second groove section being connected by a side guide surface having a slope; The second connecting portion is clamped in the first groove section, and a gap is left between the second connecting portion and the second groove section. The gap is filled with solder, and the filling height of the solder is at least 1 / 2 of the height of the second groove section.

8. An aerosol generating device, characterized in that The heating element according to claim 7 is included.

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