Three-terminal fuse and preparation method thereof

Abstract

The invention discloses a three-terminal fuse and a preparation method, the three-terminal fuse comprises a substrate and a shell, a certain space is formed between the substrate and the shell, and an electrode, a heating body layer, an insulating medium layer, a surface electrode, an alloy melt and a cosolvent layer are arranged in the space; the electrodes comprise a first electrode, a second electrode, a third electrode and a fourth electrode which are not in contact with one another, the first electrode, the second electrode and the third electrode extend from the first end face of the substrate to the second end face of the substrate, and the fourth electrode is only located on the first end face; two sides of the heating body layer are respectively connected with the third electrode and the fourth electrode; the insulating medium layer is formed on the heating body layer by an aluminum nitride material in a magnetron sputtering manner; the surface electrode is formed on the insulating dielectric layer by a metal material in a magnetron sputtering manner, and one side of the surface electrode is connected with the fourth electrode; the alloy melt is arranged on the surface electrode; and the cosolvent layer is arranged on the alloy melt. The three-terminal fuse provided by the invention can realize the functions of overcharge voltage protection and overcurrent protection.

Description

Technical Field

[0001] The 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] The three-terminal fuse is a key circuit protection component and is widely used in lithium-ion battery charging systems and portable electronic devices. The three-terminal fuse has three external connection ports for building overcurrent and overvoltage protection circuits. The three-terminal fuses commonly used at present are mostly equipped with alloy melts inside, and the melting of the alloy melt at high temperature is used to achieve circuit protection. The alloy melt melts in two situations: first, when the circuit has an overcurrent situation, the current flowing through the alloy melt increases sharply and exceeds the set value, and the alloy melt melts directly; second, when the circuit has an overvoltage situation, the secondary protection circuit triggers the MOS field effect transistor (MOSFET) to turn on the heating circuit, and the heating element layer built into the fuse is energized and heated. The heat generated is transferred to the alloy melt through the insulating medium layer above it. With the transfer of heat, the alloy melt is heated to the melting point and melts, thereby achieving circuit protection. For overvoltage situations, the efficiency of heat transfer from the heating element layer to the alloy melt is very critical, because it directly affects whether the fuse can respond quickly and disconnect the circuit in time.

[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 insulating dielectric layer is usually made by printing glass slurry and undergoing a high-temperature sintering process, and its main component is glass. However, the thermal conductivity of glass itself is relatively 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 melt for too long, and the circuit cannot be interrupted in time, causing equipment damage or even safety accidents. In addition, the currently more commonly used disposable three-terminal fuses mostly use alumina (Al 2 O 3 ) ceramic sheet as the substrate, although Al 2 O 3 Ceramic substrates have excellent electrical insulation, mechanical strength, thermal and chemical stability, but they have high thermal conductivity (about 15-35W / mK) and are prone to heat loss. Therefore, the heating element layer is usually not directly prepared on Al 2 O 3 Instead of preparing a low thermal conductivity insulating medium layer on the ceramic substrate, a heating element layer is first prepared on the insulating medium layer, and then a heating element layer is prepared on the insulating medium layer. However, this method not only fails to fundamentally solve the problem of low thermal conduction efficiency inside the device, but also increases the device thickness, device preparation difficulty and manufacturing cost.

[0004] Therefore, there is an urgent need for a three-terminal fuse and a preparation method to solve the deficiencies of the prior art. Summary of the invention

[0005] In view of the above problems, an 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 thermal conductivity 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 is formed between the substrate and the shell, and the space has electrodes, 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 are not in contact with 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 aluminum nitride material by magnetron sputtering; the surface electrode is formed on the insulating medium layer by metal material by magnetron sputtering 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 performance, but is also an ideal thermal conductive material with a thermal conductivity of up to 300W / mK or more. Therefore, aluminum nitride material is used as the insulating dielectric layer, and the thermal conductivity efficiency is much higher than that of 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 the thermal conductivity efficiency. Therefore, the three-terminal fuse of the present invention has high internal thermal conductivity. When the three-terminal fuse of the present invention is applied to a specific protection circuit, the alloy melt can be melted when overcurrent occurs, and the alloy melt of the three-terminal fuse can also be heated and melted when overcharge occurs, thereby realizing 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] Further, 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 may 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 30-500 nm. Specifically, the thickness of the surface electrode may 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 medium layer of the present invention is larger than that of the heating element layer, so that the insulating medium layer can completely cover the heating element layer, thereby effectively preventing the heating element from directly contacting the metal electrode and the 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 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 flux on the alloy melt to form a flux layer;

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

[0024] Compared with the prior art, 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 being repeatedly affected by high-temperature treatment.

[0025] Furthermore, step (2) of the present invention includes: printing silver paste on a substrate and obtaining a silver layer by high-temperature sintering; 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 by using a dispensing method.

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

[0029] Figure 1 It is a schematic diagram of the structure of the three-terminal fuse of the present invention after removing the shell.

[0030] Figure 2 The figure is a schematic diagram of the cross-sectional structure of the three-terminal fuse of the present invention after removing the shell.

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

[0032] Figure 4 It is a 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, further detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0037] In order to solve the problems of low internal thermal conductivity of three-terminal fuses and complicated preparation of three-terminal fuses in the prior art, the present invention provides a three-terminal fuse and a preparation method. Figure 1 to Figure 5 The three-terminal fuse of the present invention comprises a substrate 1 and a shell 11 arranged on the substrate 1, wherein the substrate 1 has a first end face 111 and a second end face 112 opposite to each other, and a certain space is formed between the substrate 1 and the shell 11, wherein the space comprises 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 arranged on the substrate 1, and the electrodes comprise a first electrode 2, a second electrode 3, a third electrode 4, and a fourth electrode 5 which are not in contact with each other, and 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 arranged 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 arranged 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 arranged 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 or more. Therefore, aluminum nitride material is used as the insulating dielectric layer 7, and the thermal conductivity efficiency is much higher than that of the glass-based insulating dielectric layer 7. It 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 faster; at the same time, the magnetron sputtering method does not need to be performed 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 high internal thermal conductivity. When the three-terminal fuse of the present invention is applied to a specific protection circuit, when overcurrent occurs, the alloy melt 9 can be melted, and when overcharging occurs, the alloy melt 9 of the three-terminal fuse can also be heated and melted, thereby realizing overcharge voltage protection and overcurrent protection at the same time.

[0038] Please continue to refer to Figure 1 to Figure 5The substrate 1 of the present invention is a ceramic substrate. More specifically, the substrate 1 is made of Al 2 O 3 . The substrate 1 is a rectangular parallelepiped 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 encapsulation 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 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 flux on the alloy melt 9 to form a flux layer 10;

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

[0050] Furthermore, step (1) includes ultrasonically cleaning the substrate 1 in deionized water containing a cleaning agent, deionized water, anhydrous ethanol, acetone, and isopropanol in sequence, and then removing the substrate 1 and washing it with N 2 Blow dry, and put into an oven for drying. More specifically, the ultrasonic cleaning time can be 10 to 30 minutes; the drying temperature is 100 to 130° C., and the drying time is 6 to 10 hours.

[0051] Further, step (2) comprises printing silver paste on 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 temperature of high temperature sintering 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 repeated here.

[0052] Furthermore, step (3) includes ultrasonically cleaning the substrate 1 carrying the electrode in deionized water containing a cleaning agent, deionized water, anhydrous ethanol, acetone, and isopropanol in sequence, and then removing the substrate 1 from the cleaning agent and washing it with N 2 Blow dry, and put into an oven for drying. More specifically, the ultrasonic cleaning time can be 10 to 30 minutes; the drying temperature is 100 to 130° C., and the drying time is 6 to 10 hours.

[0053] Furthermore, step (4) comprises printing the resistor paste on the substrate 1, the third electrode 4 and the fourth electrode 5 by screen printing, and obtaining the heating body layer 6 by high temperature sintering. The high temperature sintering temperature is 700-1100° C., preferably 800-1000° C. The main components of the resistor paste include conductive particles, adhesives, solvents, dispersants, leveling agents, antioxidants and stabilizers, etc., which can be purchased commercially. In addition, the screen printing method is a conventional method familiar in the art.

[0054] Furthermore, step (5) includes ultrasonically cleaning the substrate 1 carrying the electrode and the heating element layer 6 in deionized water containing a cleaning agent, deionized water, anhydrous ethanol, acetone, and isopropanol in sequence, and then removing the substrate 1 from the cleaning agent and washing it with N 2 Blow dry, and put into an oven for drying. More specifically, the ultrasonic cleaning time can be 10 to 30 minutes; the drying temperature is 100 to 130° C., and the drying time is 6 to 10 hours.

[0055] Furthermore, the conditions of the magnetron sputtering method in step (6) include: the substrate temperature is room temperature to 200°C; the background vacuum is 1×10 -6 ~1×10 -3Pa; 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 100nm to 5μm; specifically, the thickness of the insulating dielectric layer 7 may be, but is not limited to, 100nm, 200nm, 300nm, 500nm, 600nm, 800nm, 1000nm, 2μm, 3μm, 4μm, and 5μm. The thickness of the insulating dielectric layer 7 is preferably 200nm to 1μm, more preferably 200 to 800nm. Aluminum nitride not only has good insulation properties, but also excellent thermal conductivity. Its thermal conductivity is much higher than that of glass and Al2O3. 2 O 3 The thickness of the insulating dielectric layer 7 can be controlled below 5 μm by the magnetron sputtering method, so the thermal conductivity of the insulating dielectric layer 7 is much higher than that of the glass-based insulating dielectric layer 7 and Al 2 O 3 Ceramic substrate 1.

[0057] Furthermore, the conditions of the magnetron sputtering method in step (7) include: the substrate temperature is room temperature to 200°C; the 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] Further, the thickness of the surface electrode 8 of the present invention is 30 to 500 nm. Specifically, the thickness of the surface electrode 8 may be, but is not limited to, 30 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, and 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, so that the thickness of the surface electrode 8 is 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 familiar in the art, and the welding temperature is lower than 250°C.

[0060] Further, step (9) comprises coating the flux on the alloy melt 9 by a dispensing method to form a dispersing agent layer 10. The flux comprises, by weight, 1 to 10 parts of rosin, 1 to 10 parts of rosin glycerol ester, 1 to 10 parts of hydrogenated rosin, 1 to 10 parts of water-white rosin, 1 to 5 parts of paraffin, 1 to 5 parts of vaseline, 3 to 8 parts of triethanolamine, 10 to 20 parts of ethylene glycol monomethyl ether, 10 to 20 parts of ethylene glycol monobutyl ether, 5 to 15 parts of glycerol, 3 to 10 parts of citric acid, 5 to 20 parts of hydrogenated castor oil and 5 to 20 parts of silicon dioxide. The dispensing method is a method familiar 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, the subsequent preparation processes, such as preparing the insulating medium layer 7 and the surface electrode 8 by magnetron sputtering, fixing the alloy melt 9 by welding, coating the flux by dispensing method, and fixing the shell 11 by adhesive can all be carried out at a relatively low temperature (less than 250°C), which 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 in conjunction with specific embodiments.

[0064] Example 1

[0065] This embodiment provides a three-terminal fuse, including a ceramic substrate (made of Al 2 O 3 ) and a plastic shell arranged on a 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 has electrodes, a heating element layer, an insulating medium 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 arranged on two opposite sides of the ceramic substrate, the third electrode and the fourth electrode are respectively arranged on the other two opposite sides of the ceramic substrate, and the first electrode, the second electrode, and the third electrode extend from the edge area of ​​the first end face to the second end face respectively In the edge area of ​​the end face, 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 solvent 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 cleaning agent, deionized water, anhydrous ethanol, acetone, and isopropanol in sequence. Each ultrasonic cleaning lasted for 15 min. After being taken out, the substrate was cleaned with N 2 Blow dry, put in an oven and dry at 120°C for 8h;

[0068] (2) printing silver paste (purchased from Shenzhen Yilai Technology Co., Ltd., ELEC-X180) on a ceramic substrate by screen printing, sintering at 900° C. 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;

[0069] (3) The ceramic substrate carrying the electrode was ultrasonically cleaned in deionized water containing a cleaning agent, deionized water, anhydrous ethanol, acetone, and isopropanol in sequence. Each ultrasonic cleaning time was 15 min. After taking it out, it was cleaned with N 2 Blow dry, put in an oven and dry at 125°C for 7h;

[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 the heating element layer was ultrasonically cleaned in deionized water containing a cleaning agent, deionized water, anhydrous ethanol, acetone, and isopropanol in sequence. The ultrasonic cleaning time for each time was 17 min. After taking it out, it was washed with N 2 Blow dry, put in an oven and dry at 120°C for 8h;

[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; wherein 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 overall 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) Using magnetron sputtering to deposit metal Au on the insulating dielectric layer and the fourth electrode 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 is fixed on the surface electrode, the first electrode and the second electrode by a reflow soldering method, the peak temperature of the reflow soldering is lower than 245° C., and the solder paste used in the reflow soldering is a solder paste containing Sn3.0Ag0.5Cu alloy powder; wherein the alloy melt is a rectangular sheet structure, and in terms of mass fraction, the alloy melt includes 5% Sn, 92.5% Pb and 2.5% Ag;

[0075] (9) coating the flux on the alloy melt 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, 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 and the preparation method thereof provided in Example 8 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 and the preparation method thereof provided in Example 10 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 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 difference between the two is that the surface electrode of the three-terminal fuse in Comparative Example 2 is a composite electrode, and the composite electrode includes 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: the step (7) of the preparation method of the three-terminal fuse of 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 of Comparative Example 3 is a composite electrode, the composite electrode 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 the 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: the 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, which are 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 microscope test results of Examples 2 to 10 are similar to those of Example 1, which shows that the AlN film prepared by the magnetron sputtering method as the insulating dielectric layer not only helps heat conduction, but also effectively isolates the heating element layer from the surface electrode to prevent direct contact between the two.

[0105] Connect the three-terminal fuse of Example 1 of the present invention to 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 and the external circuit T 1 The second electrode is connected to the T of the external circuit. 2 The third electrode is connected to the T 3 When the circuit current increases sharply and exceeds the set value, the alloy melt is heated and melted, and the circuit is interrupted. When overcharge occurs, the secondary protection circuit triggers the MOSFET to turn on, making T 1 With T 3 The circuit between the ports is turned on, and the current is from T 1 The metal flows into the first electrode, the alloy melt, the surface electrode, the fourth electrode, the heating element layer and the third electrode, and then flows into the T 3 The heat generated by the heating element layer is quickly transferred to the alloy melt through the insulating medium layer (AlN film) and the surface electrode (Au film) with high thermal conductivity above it. The alloy melt is quickly melted by the heat, 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 are 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 the embodiment and comparative example

[0108]

[0109]

[0110] It can be seen from Table 1 that 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 solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution 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, a certain space is formed between the substrate and the shell, and the space has electrodes, a heating element layer, an insulating medium layer, a surface electrode, an alloy melt, and a flux layer; The electrodes are arranged 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, the first electrode, the second electrode, and the third electrode extend from an edge area of ​​the first end surface to an edge area of ​​the second end surface respectively, and the fourth electrode is only located on an edge area of ​​the first end surface; The heating element layer is disposed on the substrate, and two sides of the heating element layer are respectively connected to the third electrode and the fourth electrode; 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 disposed on the surface electrode and two sides of the alloy melt are respectively connected to the first electrode and the second electrode; The flux layer is disposed on the alloy melt.

2. The three-terminal fuse according to claim 1, characterized in that: 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, characterized in that: The thickness of the insulating dielectric layer is 100 nm to 5 μm.

4. The three-terminal fuse according to claim 1, characterized in that: The thickness of the surface electrode is 30-500 nm.

5. The three-terminal fuse according to claim 1, characterized in that: The area of ​​the insulating medium layer is larger than the area of ​​the heating element layer.

6. The three-terminal fuse according to claim 1, characterized in that: The electrode is a composite electrode, and comprises a silver layer and a gold layer.

7. A method for preparing a three-terminal fuse according to any one of claims 1 to 6, 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 at a high temperature to obtain a heating element layer; (5) cleaning 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 onto the substrate after step (9).

8. The method for preparing a three-terminal fuse according to claim 7, characterized in that: Step (2) includes: printing silver paste on the substrate and obtaining a silver layer through high temperature sintering; 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.

9. The method for preparing a three-terminal fuse according to claim 7, characterized in that: Step (8) includes fixing the alloy melt on the surface electrode, the first electrode and the second electrode by welding.

10. The method for preparing a three-terminal fuse according to claim 7, characterized in that: 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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