Three-terminal fuse and preparation method thereof

Abstract

The present invention discloses a three-terminal fuse and a preparation method, wherein the three-terminal fuse includes a substrate and a shell, a certain space is formed between the substrate and the shell, and the space contains electrodes, a heating element layer, an insulating dielectric layer, a surface electrode, an alloy melt, and a flux layer; the electrodes include a first electrode, a second electrode, a third electrode, and a fourth electrode that are not in contact with each other, the first electrode, the second electrode, and the third electrode respectively extending from the first end surface of the substrate to the second end surface of the substrate, and the fourth electrode is only located on the first end surface; both sides of the heating element layer are connected to the third electrode and the fourth electrode respectively; the insulating dielectric layer is formed on the heating element layer by magnetron sputtering of aluminum nitride material; the surface electrode is formed on the insulating dielectric layer by magnetron sputtering of metal material, and one side of the surface electrode is connected to the fourth electrode; the alloy melt is provided on the surface electrode; and the flux layer is provided on the alloy melt. The three-terminal fuse of the present invention can realize overcharge voltage protection and overcurrent protection functions.

Description

Technical Field

[0001] The present invention belongs to the technical field of circuit protection elements, and in particular relates to a three-terminal fuse and a preparation method thereof. Background Art

[0002] Three-terminal fuses are key circuit protection components widely used in lithium-ion battery charging systems and portable electronic devices. They have three external connection ports for implementing overcurrent and overvoltage protection circuits. Currently, commonly used three-terminal fuses often incorporate an alloy melt, which fuses circuit protection by melting at high temperatures. This melt melts in two situations: first, when an overcurrent condition occurs, the current flowing through the alloy melt increases dramatically and exceeds the set value, causing the alloy to melt directly. Second, when an overvoltage condition occurs, the secondary protection circuit triggers a MOS field-effect transistor (MOSFET), energizing the heating circuit. The fuse's internal heating element heats up, generating heat. The heat generated is transferred to the alloy melt through the insulating dielectric layer above it. As the heat is transferred, the alloy melt is heated to its melting point and melts, thus achieving circuit protection. For overvoltage conditions, the efficiency of heat transfer from the heating element layer to the alloy melt is critical, as it directly affects the fuse's ability to quickly respond and disconnect the circuit.

[0003] In the currently widely used three-terminal fuse design, an insulating dielectric layer needs to be covered above the heating element layer to prevent the heating element from directly contacting the metal electrode and alloy melt above. This layer of insulating medium is usually made by printing glass paste and undergoing a high-temperature sintering process, and its main component is glass. However, the thermal conductivity of glass itself is low (about 1W / mK), which affects the efficiency of heat conduction from the heating element layer to the alloy melt, easily causing the alloy melt to take too long to melt, and the circuit cannot be interrupted in time, which in turn causes equipment damage and even safety accidents. In addition, the currently more commonly used disposable three-terminal fuses mostly use alumina (Al2O3) ceramic sheets as the substrate. Although the Al2O3 ceramic substrate has excellent electrical insulation, mechanical strength, thermal and chemical stability, etc., its high thermal conductivity (approximately 15-35W / mK) is prone to heat loss. Therefore, the heating element layer is usually not directly prepared on the Al2O3 ceramic substrate. Instead, a low thermal conductivity insulating medium layer is first prepared on the ceramic substrate, and then the heating element layer is prepared on the insulating medium layer. However, this method not only fails to fundamentally solve the problem of low internal heat conduction efficiency of the device, but also increases the thickness of the device, the difficulty of device preparation and the manufacturing cost.

[0004] Therefore, there is an urgent need for a three-terminal fuse and a preparation method thereof to solve the deficiencies of the existing technical problems. Summary of the Invention

[0005] In view of the above problems, the object of the present invention is to provide a three-terminal fuse and a preparation method thereof, wherein the three-terminal fuse has high internal heat conduction efficiency and can simultaneously achieve overcharge voltage protection and overcurrent protection.

[0006] To achieve the above objectives, the first aspect of the present invention provides a three-terminal fuse, including a substrate and a shell arranged on the substrate, the substrate having a first end face and a second end face opposite to each other, a certain space being formed between the substrate and the shell, the space containing an electrode, a heating element layer, an insulating medium layer, a surface electrode, an alloy melt, and a flux layer; the electrode is arranged on the substrate, and the electrodes include a first electrode, a second electrode, a third electrode, and a fourth electrode that do not contact each other, the first electrode, the second electrode, and the third electrode respectively extend from the edge area of ​​the first end face to the edge area of ​​the second end face, and the fourth electrode is only located on the edge area of ​​the first end face; the heating element layer is arranged on the substrate and the two sides of the heating element layer are respectively connected to the third electrode and the fourth electrode; the insulating medium layer is formed on the heating element layer by magnetron sputtering of aluminum nitride material; the surface electrode is formed on the insulating medium layer by magnetron sputtering of metal material and one side of the surface electrode is connected to the fourth electrode; the alloy melt is arranged on the surface electrode and the two sides of the alloy melt are respectively connected to the first electrode and the second electrode; the flux layer is arranged on the alloy melt.

[0007] Compared with the prior art, the three-terminal fuse provided by the present invention has an insulating dielectric layer formed on the heating element layer by magnetron sputtering of aluminum nitride material. Aluminum nitride not only has excellent insulation properties, but is also an ideal thermal conductive material with a thermal conductivity of up to 300W / mK. Therefore, the use of aluminum nitride material as the insulating dielectric layer has a much higher thermal conductivity efficiency than the glass-based insulating dielectric layer, which can significantly improve the efficiency of heat conduction from the heating element layer to the alloy melt during overvoltage, effectively avoiding heat loss, thereby ensuring the rapid melting of the alloy melt. In addition, the present invention uses magnetron sputtering to form the insulating dielectric layer and the surface electrode, which can finely control the thickness of the insulating dielectric layer and the surface electrode in a thinner direction, thereby further optimizing the heat conduction path and making the alloy melt melt faster; at the same time, the magnetron sputtering method does not need to be carried out at high temperature, which avoids repeated high temperature damage to the heating element layer, thereby further ensuring thermal conductivity efficiency. Therefore, the three-terminal fuse of the present invention has a high internal thermal conductivity. When the three-terminal fuse of the present invention is applied to a specific protection circuit, when an overcurrent occurs, the alloy melt can be melted. When an overcharge occurs, the alloy melt of the three-terminal fuse can also be heated and melted, thereby achieving overcharge voltage protection and overcurrent protection at the same time.

[0008] Furthermore, the substrate of the present invention is a cuboid, the first electrode and the second electrode are respectively arranged on two opposite sides of the substrate, and the third electrode and the fourth electrode are respectively arranged on the other two opposite sides of the substrate.

[0009] Furthermore, the thickness of the insulating dielectric layer of the present invention is 100 nm to 5 μm. Specifically, the thickness of the insulating dielectric layer can be, but is not limited to, 100 nm, 200 nm, 300 nm, 500 nm, 600 nm, 800 nm, 1000 nm, 2 μm, 3 μm, 4 μm, or 5 μm.

[0010] Furthermore, the thickness of the surface electrode of the present invention is 30 to 500 nm. Specifically, the thickness of the surface electrode can be, but is not limited to, 30 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, or 500 nm.

[0011] Furthermore, the area of ​​the insulating dielectric layer of the present invention is larger than that of the heating element layer, which enables the insulating dielectric layer to completely cover the heating element layer, thereby effectively preventing the heating element from directly contacting the metal electrode and alloy melt above.

[0012] Furthermore, the electrode of the present invention is a composite electrode, and the electrode includes a silver layer and a gold layer.

[0013] Accordingly, the second aspect of the present invention further provides a method for preparing a three-terminal fuse, the steps comprising:

[0014] (1) Cleaning and drying the substrate;

[0015] (2) preparing a first electrode, a second electrode, a third electrode, and a fourth electrode on a substrate;

[0016] (3) washing and drying after step (2);

[0017] (4) Printing the resistor paste on the substrate, the third electrode, and the fourth electrode, and sintering at a high temperature to obtain a heating element layer;

[0018] (5) washing and drying after step (4);

[0019] (6) depositing aluminum nitride material on the heating element layer by magnetron sputtering to form an insulating dielectric layer;

[0020] (7) depositing a metal material on the insulating dielectric layer and the fourth electrode by magnetron sputtering to form a surface electrode;

[0021] (8) Fixing the alloy melt on the surface electrode, the first electrode and the second electrode;

[0022] (9) coating the alloy melt with flux to form a flux layer;

[0023] (10) Fix the shell onto the substrate after step (9).

[0024] Compared with the existing technology, the present invention adopts aluminum nitride material with high thermal conductivity as the insulating medium layer, which improves the efficiency of heat transfer from the heating element layer to the alloy melt; and forms the insulating medium layer and the surface electrode through magnetron sputtering technology, which not only simplifies the process flow, but also further optimizes the heat conduction path and avoids the heating element layer from being affected by repeated high-temperature treatment.

[0025] Furthermore, step (2) of the present invention includes: printing silver paste on a substrate and sintering it at a high temperature to obtain a silver layer; and then chemically plating a gold layer on the silver layer to obtain a first electrode, a second electrode, a third electrode, and a fourth electrode, respectively.

[0026] Furthermore, step (8) of the present invention includes fixing the alloy melt on the surface electrode, the first electrode and the second electrode by welding.

[0027] Furthermore, step (9) of the present invention includes coating the flux on the alloy melt using a dispensing method.

[0028] Furthermore, step (10) of the present invention includes fixing the shell to the substrate after step (9) using an adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic structural diagram of the three-terminal fuse of the present invention with the housing removed.

[0030] Figure 2 This is a schematic cross-sectional view of the three-terminal fuse of the present invention with the housing removed.

[0031] Figure 3 It is a schematic diagram of the front structure of the substrate carrying electrodes of the present invention.

[0032] Figure 4 Schematic diagram of the back structure of the substrate carrying electrodes of the present invention.

[0033] Figure 5 The present invention is a process flow chart of a method for preparing a three-terminal fuse.

[0034] Figure 6 This is a scanning electron microscope image of the insulating dielectric layer in the three-terminal fuse of Example 1 of the present invention.

[0035] Figure 7 This is a schematic diagram of connecting the three-terminal fuse of Example 1 of the present invention to a circuit for testing. DETAILED DESCRIPTION

[0036] In order to better illustrate the purpose, technical solutions and beneficial effects of the present invention, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0037] In order to solve the problems of low internal heat conduction efficiency and complicated preparation of three-terminal fuses in the prior art, the present invention provides a three-terminal fuse and a preparation method. Figures 1 to 5 The three-terminal fuse of the present invention includes a substrate 1 and a shell 11 provided on the substrate 1. The substrate 1 has a first end face 111 and a second end face 112 opposite to each other. A certain space is formed between the substrate 1 and the shell 11. The space contains electrodes, a heating element layer 6, an insulating medium layer 7, a surface electrode 8, an alloy melt 9, and a flux layer 10. The electrodes are provided on the substrate 1. The electrodes include a first electrode 2, a second electrode 3, a third electrode 4, and a fourth electrode 5 that are not in contact with each other. The first electrode 2, the second electrode 3, and the third electrode 4 extend from the edge area of ​​the first end face 111 to the second end face 112 respectively. 12, the fourth electrode 5 is only located on the edge area of ​​the first end face 111; the heating body layer 6 is provided on the substrate 1 and the two sides of the heating body layer 6 are respectively connected to the third electrode 4 and the fourth electrode 5; the insulating medium layer 7 is formed on the heating body layer 6 by magnetron sputtering of aluminum nitride material; the surface electrode 8 is formed on the insulating medium layer 7 by magnetron sputtering of metal material and one side of the surface electrode 8 is connected to the fourth electrode 5; the alloy melt 9 is provided on the surface electrode 8 and the two sides of the alloy melt 9 are respectively connected to the first electrode 2 and the second electrode 3; the solvent layer 10 is provided on the alloy melt 9. The three-terminal fuse provided by the present invention has an insulating dielectric layer 7 formed on the heating element layer 6 by magnetron sputtering of aluminum nitride material. Aluminum nitride not only has excellent insulation properties, but is also an ideal thermal conductive material with a thermal conductivity of up to 300W / mK. Therefore, the use of aluminum nitride material as the insulating dielectric layer 7 has a much higher thermal conductivity efficiency than the glass-based insulating dielectric layer 7, which can significantly improve the efficiency of heat conduction from the heating element layer 6 to the alloy melt 9 during overvoltage, effectively avoiding heat loss, thereby ensuring the rapid melting of the alloy melt 9. In addition, the present invention uses magnetron sputtering to form the insulating dielectric layer 7 and the surface electrode 8, which can finely control the thickness of the insulating dielectric layer 7 and the surface electrode 8 in a thinner direction, thereby further optimizing the heat conduction path and making the alloy melt 9 melt more quickly; at the same time, the magnetron sputtering method does not need to be carried out at high temperature, which avoids repeated high temperature damage to the heating element layer 6, thereby further ensuring thermal conductivity efficiency. Therefore, the three-terminal fuse of the present invention has a high internal thermal conductivity. When the three-terminal fuse of the present invention is applied to a specific protection circuit, when an overcurrent occurs, the alloy melt 9 can be melted. When overcharging occurs, the alloy melt 9 of the three-terminal fuse can also be heated and melted, thereby achieving overcharge voltage protection and overcurrent protection at the same time.

[0038] Please continue to refer to Figures 1 to 5The substrate 1 of the present invention is a ceramic substrate. More specifically, the material of the substrate 1 is Al2O3. The substrate 1 is a rectangular structure, and the specific values ​​of length, width and height can be adjusted according to actual needs. More specifically, the first electrode 2 and the second electrode 3 are respectively arranged on two opposite sides of the substrate 1, and the third electrode 4 and the fourth electrode 5 are respectively arranged on the other two opposite sides of the substrate 1; wherein the first electrode 2, the second electrode 3 and the third electrode 4 are used to connect to an external circuit. More specifically, the heating element layer 6 of the present invention is located on the central area of ​​the substrate 1, and the shell 11 is preferably made of plastic, and the shell 11 plays a role of packaging and protection for the three-terminal fuse.

[0039] Please refer to Figure 5 The present invention also provides a method for preparing a three-terminal fuse, the steps comprising:

[0040] (1) Cleaning and drying the substrate 1;

[0041] (2) preparing a first electrode 2, a second electrode 3, a third electrode 4, and a fourth electrode 5 on a substrate 1;

[0042] (3) washing and drying after step (2);

[0043] (4) Printing the resistor paste on the substrate 1, the third electrode 4 and the fourth electrode 5, and sintering at a high temperature to obtain the heating element layer 6;

[0044] (5) washing and drying after step (4);

[0045] (6) depositing aluminum nitride material on the heating element layer 6 by magnetron sputtering to form an insulating dielectric layer 7;

[0046] (7) depositing a metal material on the insulating dielectric layer 7 and the fourth electrode 5 by magnetron sputtering to form a surface electrode 8;

[0047] (8) Fixing the alloy melt 9 on the surface electrode 8, the first electrode 2 and the second electrode 3;

[0048] (9) coating the alloy melt 9 with flux to form a flux layer 10;

[0049] (10) Fix the housing 11 on the substrate 1 after step (9).

[0050] Furthermore, step (1) includes ultrasonically cleaning the substrate 1 in deionized water containing a detergent, deionized water, anhydrous ethanol, acetone, and isopropyl alcohol, in sequence, removing the substrate from the cleaning solution and drying it with nitrogen, and then drying the substrate in an oven. More specifically, the ultrasonic cleaning time can be 10 to 30 minutes; the drying temperature can be 100 to 130° C., and the drying time can be 6 to 10 hours.

[0051] Furthermore, step (2) comprises printing silver paste on the substrate 1 by screen printing, obtaining a silver layer by high-temperature sintering, and then chemically plating a gold layer on the silver layer to obtain a first electrode 2, a second electrode 3, a third electrode 4, and a fourth electrode 5, respectively. The high-temperature sintering temperature is 700-1100° C., preferably 800-1000° C. The main components of the silver paste include silver powder, adhesive, solvent, dispersant, leveling agent, antioxidant and stabilizer, etc., which can be purchased commercially. In addition, the screen printing method and the chemical gold plating method are conventional methods familiar to those skilled in the art, so they will not be described in detail here.

[0052] Furthermore, step (3) includes ultrasonically cleaning the substrate 1 carrying the electrodes in deionized water containing a detergent, deionized water, anhydrous ethanol, acetone, and isopropyl alcohol, followed by drying with nitrogen and placing it in an oven. More specifically, the ultrasonic cleaning time can be 10 to 30 minutes; the drying temperature can be 100 to 130°C, and the drying time can be 6 to 10 hours.

[0053] Furthermore, step (4) includes screen printing a resistor paste onto the substrate 1, the third electrode 4, and the fourth electrode 5, followed by high-temperature sintering to obtain the heating element layer 6. The high-temperature sintering temperature is 700-1100°C, preferably 800-1000°C. The resistor paste mainly comprises conductive particles, a binder, a solvent, a dispersant, a leveling agent, an antioxidant, and a stabilizer, and can be purchased commercially. Furthermore, the screen printing method is a conventional method known in the art.

[0054] Furthermore, step (5) includes ultrasonically cleaning the substrate 1 carrying the electrodes and the heating element layer 6 in deionized water containing a cleaning agent, deionized water, anhydrous ethanol, acetone, and isopropyl alcohol, followed by drying with nitrogen and placing the substrate in an oven. More specifically, the ultrasonic cleaning time can be 10 to 30 minutes; the drying temperature can be 100 to 130°C, and the drying time can be 6 to 10 hours.

[0055] Furthermore, the conditions of the magnetron sputtering method in step (6) include: substrate temperature is room temperature to 200°C; background vacuum is 1×10 -6 ~1×10 -3 Pa; the sputtering gas and the reaction gas are argon and nitrogen respectively, and the purity of both is 99.99%; the target material is an Al target with a purity of 99.999%; the distance from the target material to the substrate is 5 to 15 cm; the overall pressure of the working gas is 0.1 to 3.0 Pa, preferably 0.5 to 2.0 Pa, and more preferably 0.8 to 1.2 Pa; the flow ratio of argon and nitrogen is 8:1 to 1:1, preferably 4:1 to 1:1, and more preferably 2:1 to 1:1; the sputtering power is 100 to 500 W, preferably 150 to 400 W, and more preferably 200 to 350 W.

[0056] Furthermore, the thickness of the insulating dielectric layer 7 of the present invention is 100 nm to 5 μm; specifically, the thickness of the insulating dielectric layer 7 can be, but is not limited to, 100 nm, 200 nm, 300 nm, 500 nm, 600 nm, 800 nm, 1000 nm, 2 μm, 3 μm, 4 μm, or 5 μm. The thickness of the insulating dielectric layer 7 is preferably 200 nm to 1 μm, more preferably 200 to 800 nm. Aluminum nitride not only has excellent insulation properties but also excellent thermal conductivity, with a thermal conductivity far higher than that of materials such as glass and Al2O3. Furthermore, the magnetron sputtering method can control the thickness of the insulating dielectric layer 7 to below 5 μm. Therefore, the resulting insulating dielectric layer 7 has a much higher thermal conductivity efficiency than glass-based insulating dielectric layers 7 and Al2O3 ceramic substrates 1.

[0057] Furthermore, the conditions of the magnetron sputtering method in step (7) include: substrate temperature is room temperature to 200°C; background vacuum is 1×10 -6 ~1×10 -3 Pa; the sputtering gas is argon with a purity of 99.99%; the target material is an Au target with a purity of 99.999%; the distance from the target material to the substrate is 5 to 15 cm; the working gas pressure is 0.2 to 6.0 Pa, preferably 1.0 to 4.0 Pa, and more preferably 1.5 to 3.5 Pa; the sputtering power is 1 to 20 W, preferably 5 to 15 W, and more preferably 8 to 12 W.

[0058] Furthermore, the thickness of the surface electrode 8 of the present invention is 30 to 500 nm. Specifically, the thickness of the surface electrode 8 can be, but is not limited to, 30 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, or 500 nm. The thickness of the surface electrode 8 is preferably 80 to 300 nm, more preferably 100 to 200 nm. The surface electrode 8 (made of Au) is prepared by magnetron sputtering, which can make the thickness of the surface electrode 8 less than 500 nm, which can further improve the heat conduction efficiency.

[0059] Furthermore, step (8) of the present invention includes fixing the alloy melt 9 on the surface electrode 8, the first electrode 2 and the second electrode 3 by a welding method. Specifically, the material of the alloy melt 9 can be but is not limited to In, Sn, In-Bi, In-Cd, In-Ag, In-Pb, In-Sn, Sn-Cd, Sn-Pb, Sn-Zn, Sn-Au, Sn-Ag, Sn-Bi, Sn-Cu, Sn-Sb, Pb-Bi, Pb-Cd, In-Sn-Bi, In-Sn-Cd, In-Sn- The thickness of the alloy melt 9 can be 0.08 to 2 mm. The welding method is a method known in the art, and the welding temperature is less than 250°C.

[0060] Furthermore, step (9) includes coating the alloy melt 9 with a flux by a dispensing method to form a flux layer 10. The flux comprises, by weight, 1-10 parts of rosin, 1-10 parts of rosin glycerol ester, 1-10 parts of hydrogenated rosin, 1-10 parts of water-white rosin, 1-5 parts of paraffin wax, 1-5 parts of vaseline, 3-8 parts of triethanolamine, 10-20 parts of ethylene glycol monomethyl ether, 10-20 parts of ethylene glycol monobutyl ether, 5-15 parts of glycerol, 3-10 parts of citric acid, 5-20 parts of hydrogenated castor oil, and 5-20 parts of silicon dioxide. The dispensing method is a method well known in the art.

[0061] Furthermore, step (10) includes fixing the housing 11 on the substrate 1 after step (9) by using an adhesive, wherein the adhesive method is a method well known in the art.

[0062] In summary, it can be seen that during the preparation process of the three-terminal fuse of the present invention, except that the preparation of the first electrode 2, the second electrode 3, the third electrode 4, the fourth electrode 5 and the heating element layer 6 requires high-temperature (700-1100°C) sintering, subsequent preparation processes, such as using magnetron sputtering to prepare the insulating dielectric layer 7 and the surface electrode 8, using welding to fix the alloy melt 9, using a dispensing method to coat the flux, and using an adhesive to fix the shell 11 can all be carried out at a relatively low temperature (less than 250°C). This avoids the damage to the heating element layer 6 caused by repeated high-temperature sintering, and helps to improve the performance and stability of the three-terminal fuse.

[0063] The purpose, technical solutions and beneficial effects of the present invention will be further explained below with reference to specific embodiments.

[0064] Example 1

[0065] This embodiment provides a three-terminal fuse, including a ceramic substrate (made of Al2O3) and a plastic shell provided on the ceramic substrate. The ceramic substrate is a rectangular parallelepiped, having a first end face and a second end face opposite to each other. A certain space is formed between the ceramic substrate and the shell, and the space contains electrodes, a heating element layer, an insulating dielectric layer, a surface electrode, an alloy melt, and a flux layer. The electrodes include a first electrode, a second electrode, a third electrode, and a fourth electrode that are not in contact with each other. The first electrode and the second electrode are respectively provided on two opposite sides of the ceramic substrate, and the third electrode and the fourth electrode are respectively provided on the other two opposite sides of the ceramic substrate. The first electrode, the second electrode, and the third electrode are respectively provided on the other two opposite sides of the ceramic substrate. It extends from the edge area of ​​the first end face to the edge area of ​​the second end face, and the fourth electrode is only located on the edge area of ​​the first end face; the heating element layer is arranged on the ceramic substrate and the two sides of the heating element layer are respectively connected to the third electrode and the fourth electrode; the insulating medium layer is formed on the heating element layer by aluminum nitride material by magnetron sputtering, and the thickness of the insulating medium layer is 800nm; the surface electrode is formed on the insulating medium layer by metal Au by magnetron sputtering and one side of the surface electrode is connected to the fourth electrode, and the thickness of the surface electrode is 200nm; the alloy melt is arranged on the surface electrode and the two sides of the alloy melt are respectively connected to the first electrode and the second electrode; the flux layer is arranged on the alloy melt.

[0066] This embodiment also provides a method for preparing a three-terminal fuse, the steps comprising:

[0067] (1) The ceramic substrate was ultrasonically cleaned in deionized water containing a detergent, deionized water, anhydrous ethanol, acetone, and isopropanol in sequence. Each ultrasonic cleaning time was 15 min. After being taken out, it was blown dry with N2 and placed in an oven for drying at 120°C for 8 h.

[0068] (2) silver paste (purchased from Shenzhen Yilai Technology Co., Ltd., ELEC-X180) was printed on a ceramic substrate by screen printing, and sintered at 900°C to obtain a silver layer, and then a gold layer was chemically plated on the silver layer to obtain a first electrode, a second electrode, a third electrode, and a fourth electrode respectively;

[0069] (3) The ceramic substrate carrying the electrode was ultrasonically cleaned in deionized water containing a detergent, deionized water, anhydrous ethanol, acetone, and isopropanol in sequence. Each ultrasonic cleaning time was 15 min. After being taken out, it was blown dry with N2 and placed in an oven for drying at 125°C for 7 h.

[0070] (4) Printing a resistor paste (purchased from Shenzhen Saiya Electronic Paste Co., Ltd.) on the ceramic substrate, the third electrode, and the fourth electrode by screen printing, and sintering at a high temperature of 1000° C. to obtain a heating element layer;

[0071] (5) The ceramic substrate carrying the electrode and heating element layer was ultrasonically cleaned in deionized water containing a detergent, deionized water, anhydrous ethanol, acetone, and isopropanol in sequence. Each ultrasonic cleaning time was 17 minutes. After being taken out, it was blown dry with N2 and placed in an oven for drying at 120°C for 8 hours.

[0072] (6) Aluminum nitride material is deposited on the heating element layer by magnetron sputtering to form an insulating dielectric layer with a thickness of 800 nm; the conditions of the magnetron sputtering method include: the substrate temperature is room temperature; the background vacuum is 1×10 -4 Pa; the sputtering gas and reaction gas are argon and nitrogen, respectively, both with a purity of 99.99%; the target is an Al target with a purity of 99.999%; the distance from the target to the substrate is 10 cm; the total pressure of the working gas is 1 Pa; the flow ratio of argon and nitrogen is 2:1; the sputtering power is 300 W;

[0073] (7) Metal Au is deposited on the insulating dielectric layer and the fourth electrode by magnetron sputtering to form a surface electrode with a thickness of 200 nm; the conditions of the magnetron sputtering method include: the substrate temperature is room temperature; the background vacuum is 1×10 -4 Pa; the sputtering gas is argon with a purity of 99.99%; the target is an Au target with a purity of 99.999%; the distance from the target to the substrate is 8 cm; the working gas pressure is 3.0 Pa; the sputtering power is 10 W;

[0074] (8) A 0.1 mm thick alloy melt was fixed on the surface electrode, the first electrode, and the second electrode by a reflow soldering method, wherein the peak temperature of the reflow soldering was lower than 245°C, and the solder paste used in the reflow soldering was a solder paste containing Sn3.0Ag0.5Cu alloy powder; wherein the alloy melt had a rectangular sheet structure and, by mass fraction, comprised 5% Sn, 92.5% Pb, and 2.5% Ag;

[0075] (9) coating the alloy melt with a flux by a dispensing method to form a flux layer; wherein the flux comprises, by weight, 5 parts of rosin, 6 parts of rosin glycerol ester, 7 parts of hydrogenated rosin, 5 parts of water-white rosin, 3 parts of paraffin wax, 2 parts of vaseline, 4 parts of triethanolamine, 16 parts of ethylene glycol monomethyl ether, 17 parts of ethylene glycol monobutyl ether, 8 parts of glycerol, 6 parts of citric acid, 17 parts of hydrogenated castor oil and 10 parts of silicon dioxide;

[0076] (10) Using adhesive to fix the plastic shell on the ceramic substrate after step (9).

[0077] Example 2

[0078] The three-terminal fuse and the preparation method thereof provided in Example 2 are substantially the same as those in Example 1. The only difference between Example 2 and Example 1 is that the thickness of the insulating dielectric layer in Example 2 is 200 nm.

[0079] Example 3

[0080] The three-terminal fuse and the preparation method thereof provided in Example 3 are substantially the same as those in Example 1. The only difference between Example 3 and Example 1 is that the thickness of the insulating dielectric layer in Example 3 is 300 nm.

[0081] Example 4

[0082] The three-terminal fuse and the preparation method thereof provided in Example 4 are substantially the same as those in Example 1. The only difference between Example 4 and Example 1 is that the thickness of the insulating dielectric layer in Example 4 is 400 nm.

[0083] Example 5

[0084] The three-terminal fuse and the preparation method thereof provided in Example 5 are substantially the same as those in Example 1. The only difference between Example 5 and Example 1 is that the thickness of the insulating dielectric layer in Example 5 is 500 nm.

[0085] Example 6

[0086] The three-terminal fuse and the preparation method thereof provided in Example 6 are substantially the same as those in Example 1. The only difference between Example 6 and Example 1 is that the thickness of the insulating dielectric layer in Example 6 is 600 nm.

[0087] Example 7

[0088] The three-terminal fuse and the preparation method thereof provided in Example 7 are substantially the same as those in Example 1. The only difference between Example 7 and Example 1 is that the thickness of the insulating dielectric layer in Example 7 is 700 nm.

[0089] Example 8

[0090] The three-terminal fuse provided in Example 8 and the preparation method thereof are substantially the same as those in Example 1. The only difference between Example 8 and Example 1 is that the thickness of the surface electrode in Example 8 is 100 nm.

[0091] Example 9

[0092] The three-terminal fuse provided in Example 9 and the preparation method thereof are substantially the same as those in Example 1. The only difference between Example 9 and Example 1 is that the thickness of the surface electrode in Example 9 is 150 nm.

[0093] Example 10

[0094] The three-terminal fuse provided in Example 10 and the preparation method thereof are substantially the same as those in Example 1. The only difference between Example 10 and Example 1 is that the thickness of the surface electrode in Example 10 is 180 nm.

[0095] Comparative Example 1

[0096] The three-terminal fuse provided in Comparative Example 1 is substantially the same as that in Example 1, the only difference between the two is that the insulating dielectric layer of the three-terminal fuse in Comparative Example 1 is formed on the heating element layer by high-temperature sintering of insulating dielectric slurry.

[0097] The preparation method of the three-terminal fuse provided in Comparative Example 1 is basically the same as that in Example 1, the only difference between the two is that: step (6) of the preparation method of the three-terminal fuse of Comparative Example 1 includes: printing the insulating dielectric slurry on the heating element layer by screen printing, and sintering at 850°C to form an insulating dielectric layer with a thickness of 30 μm; wherein the insulating dielectric slurry includes borosilicate glass powder, resin and organic solvent, and is purchased from Foshan Jinggu Material Technology Co., Ltd.

[0098] Comparative Example 2

[0099] The three-terminal fuse provided in Comparative Example 2 is substantially the same as that in Example 1, and the only difference between the two is that the surface electrode of the three-terminal fuse in Comparative Example 2 is a composite electrode including a silver layer and a gold layer.

[0100] The preparation method of the three-terminal fuse provided in Comparative Example 2 is basically the same as that in Example 1, the only difference between the two is that: Step (7) of the preparation method of the three-terminal fuse in Comparative Example 2 includes: printing silver paste (purchased from Shenzhen Yilai Technology Co., Ltd., ELEC-X180) on the insulating dielectric layer and the fourth electrode by screen printing, sintering at 850°C to obtain a silver electrode, and then chemically gold-plating the silver electrode to obtain a surface electrode with a thickness of 30 μm.

[0101] Comparative Example 3

[0102] The three-terminal fuse provided in Comparative Example 3 is basically the same as that in Example 1, the only difference between the two is that the surface electrode of the three-terminal fuse in Comparative Example 3 is a composite electrode, which includes a silver layer and a gold layer; and the insulating dielectric layer is formed on the heating element layer by high-temperature sintering of an insulating dielectric slurry.

[0103] The preparation method of the three-terminal fuse provided in Comparative Example 3 is basically the same as that in Example 1, the only difference between the two is that: step (6) of the preparation method of the three-terminal fuse of Comparative Example 3 includes: printing the insulating dielectric slurry on the heating element layer by screen printing, and sintering at 850°C to form an insulating dielectric layer with a thickness of 30 μm; wherein the insulating dielectric slurry includes borosilicate glass powder, resin and organic solvent, and is purchased from Foshan Jinggu Materials Technology Co., Ltd.; and step (7) includes: printing silver paste (purchased from Shenzhen Yilai Technology Co., Ltd., ELEC-X180) on the insulating dielectric layer and the fourth electrode by screen printing, sintering at 850°C to obtain a silver electrode, and then chemically gold-plating the silver electrode to obtain a surface electrode with a thickness of 30 μm.

[0104] The morphology of the insulating dielectric layer in the three-terminal fuse of Example 1 was observed using a scanning electron microscope. The results are as follows: Figure 6 As shown. Figure 6 It can be seen that the insulating dielectric layer has a dense structure and uniform morphology. The scanning electron microscopy test results of Examples 2 to 10 are similar to those of Example 1, indicating that the AlN film prepared by magnetron sputtering as the insulating dielectric layer not only facilitates heat conduction but also effectively isolates the heating element layer from the surface electrode, preventing direct contact between the two.

[0105] Connect the three-terminal fuse of Example 1 of the present invention to the Figure 7 The secondary protection circuit shown in the figure is tested, and the three-terminal fuse is used as the protection component of the secondary protection circuit; combined with Figure 1 Specifically, the first electrode is connected to the T1 port of the external circuit, the second electrode is connected to the T2 port of the external circuit, and the third electrode is connected to the T3 port of the external circuit; when the circuit current increases sharply and exceeds the set value, the alloy melt is heated and melted, and the circuit is interrupted. When an overcharge occurs, the secondary protection circuit triggers the MOSFET to turn on, so that the circuit between the T1 and T3 ports is turned on, and the current flows into the T1 port, passes through the first electrode, the alloy melt, the surface electrode, the fourth electrode, the heating element layer and the third electrode, and then flows out from the T3 port. The heating element layer is energized and heated, and the heat generated is quickly transferred to the alloy melt through the highly thermally conductive insulating medium layer (AlN film) and the surface electrode (Au film) above it. The alloy melt is quickly heated and melted, thereby cutting off the circuit. More specifically, the test results show that the three-terminal fuse prepared in Example 1 has a melting time of 10.65s under overcurrent (60A) and a melting time of 1.36s under overvoltage (62V).

[0106] The three-terminal fuses of Examples 2 to 10 and Comparative Examples 1 to 3 were also connected to the following Figure 7 The test was carried out in the secondary protection circuit shown in FIG. 1 , and the test results are shown in Table 1.

[0107] Table 1 Overcurrent and overvoltage test results of three-terminal fuses of embodiment and comparative example

[0108]

[0109]

[0110] As can be seen from Table 1, the three-terminal fuses of Examples 1 to 10 can achieve overcharge voltage protection and overcurrent protection functions, which shows that the AlN insulating dielectric layer and Au surface electrode formed by the magnetron sputtering method have better thermal conductivity than the glass-based insulating dielectric layer and Au electrode prepared by screen printing and high-temperature sintering methods.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A three-terminal fuse, characterized in that: The invention comprises a substrate and a shell provided on the substrate, wherein the substrate has a first end face and a second end face opposite to each other, and a certain space is formed between the substrate and the shell, wherein the space contains electrodes, a heating element layer, an insulating medium layer, a surface electrode, an alloy melt, and a flux layer; the electrodes are provided on the substrate, and the electrodes include a first electrode, a second electrode, a third electrode, and a fourth electrode that are not in contact with each other, wherein the first electrode, the second electrode, and the third electrode extend from an edge region of the first end face to an edge region of the second end face respectively, and the fourth electrode is located only on an edge region of the first end face; The heating element layer is provided on the substrate, and two sides of the heating element layer are connected to the third electrode and the fourth electrode respectively; The insulating dielectric layer is formed on the heating element layer by magnetron sputtering of aluminum nitride material; The surface electrode is formed on the insulating dielectric layer by magnetron sputtering of a metal material, and one side of the surface electrode is connected to the fourth electrode; The alloy melt is arranged on the surface electrode, and two sides of the alloy melt are connected to the first electrode and the second electrode respectively; The flux layer is provided on the alloy melt; The thickness of the insulating dielectric layer is 100 nm to 5 μm; The thickness of the surface electrode is 30 to 500 nm. The area of ​​the insulating medium layer is larger than the area of ​​the heating element layer.

2. The three-terminal fuse according to claim 1, wherein: The substrate is a cuboid, the first electrode and the second electrode are respectively arranged on two opposite sides of the substrate, and the third electrode and the fourth electrode are respectively arranged on the other two opposite sides of the substrate.

3. The three-terminal fuse according to claim 1, wherein: The electrode is a composite electrode, comprising a silver layer and a gold layer.

4. A method for preparing a three-terminal fuse according to any one of claims 1 to 3, characterized in that the steps include: (1) Cleaning and drying the substrate; (2) preparing a first electrode, a second electrode, a third electrode, and a fourth electrode on the substrate; (3) washing and drying after step (2); (4) printing a resistor paste on the substrate, the third electrode, and the fourth electrode, and sintering the printed resistor paste at a high temperature to obtain a heating element layer; (5) washing and drying after step (4); (6) depositing aluminum nitride material on the heating element layer by magnetron sputtering to form an insulating dielectric layer; (7) depositing a metal material on the insulating dielectric layer and the fourth electrode by magnetron sputtering to form a surface electrode; (8) fixing the alloy melt on the surface electrode, the first electrode and the second electrode; (9) coating the alloy melt with a flux to form a flux layer; (10) Fix the housing on the substrate after step (9).

5. The method for preparing a three-terminal fuse according to claim 4, wherein: Step (2) includes: printing silver paste on the substrate and sintering it at high temperature to obtain a silver layer; and then chemically plating a gold layer on the silver layer to obtain the first electrode, the second electrode, the third electrode, and the fourth electrode.

6. The method for preparing a three-terminal fuse according to claim 4, wherein: Step (8) includes fixing the alloy melt on the surface electrode, the first electrode and the second electrode by welding.

7. The method for preparing a three-terminal fuse according to claim 4, wherein: Step (9) includes coating the flux on the alloy melt by using a dispensing method; and step (10) includes fixing the shell on the substrate after step (9) by using an adhesive.

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