Thermal protection type piezoresistor component manufacturing method

Abstract

The invention discloses a thermal protection type piezoresistor component manufacturing method which comprises the following steps: manufacturing pin supports including an upper pin support, a middle pin support and a lower pin support; the pin support is placed in a welding tool mold; welding flux is dispensed or coated at the welding position of the lower pin support; placing the chip-type pressure-sensitive chip on the lower pin support; solder needing to be connected with the fusible metal is dispensed or coated on the upper surface of the chip-type pressure-sensitive chip; solder needing to be connected with the fusible metal is dispensed or coated on the upper and middle pin supports; the two ends of the fusible metal are placed on the upper surface of the chip-type pressure-sensitive chip and the welding positions of the upper pin support and the middle pin support; welding the sheet-type pressure-sensitive chip, the pin support and the fusible metal together; packaging the welded components into an insulating plastic packaging layer by adopting a plastic packaging process; and then trimming to form a thermal protection type varistor component product. By using the method provided by the invention, the thermal protection type piezoresistor component with small volume and low cost can be produced in batches.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a heat protection type varistor component, and belongs to the technical field of electronic components. Background Art

[0002] The performance of varistor (MOV) will decay during use or after long-term use. For example, the varistor voltage decreases and the leakage current increases, which will cause the current passing through the varistor to increase greatly, the product temperature rises, and eventually cause the product to explode. In severe cases, there will be arcs and open flames. In order to avoid the above situation, a varistor (TMOV) with over-temperature protection has been developed.

[0003] There are two main categories of thermally protected varistors (TMOVs) on the market: (1) Varistor + temperature fuse / temperature fuse: The welded varistor and temperature fuse / temperature fuse are bonded together and then encapsulated with epoxy resin. The advantage of this type of product is its simple structure; the disadvantages are its large size, slow response speed and high cost.

[0004] (2) Varistor + ceramic body + fusible metal: First, glue and fix the ceramic sheet (or ceramic device base) on the chip varistor, then weld the leads on both sides of the chip, then weld one end of the fusible metal to the third lead fixed on the ceramic sheet, and weld the other end of the fusible metal to the same side of the chip varistor (some ceramic devices have a cover, then add the cover), and then use environmental resin material to encapsulate. The disadvantages of this type of product are large size, the welding temperature during welding has an impact on the fusible metal, the epoxy resin curing temperature has an impact on the fusible metal, most of them are manual operations, and the product quality consistency is poor.

[0005] The thermal fuse or thermal fuse mentioned in the above products is a single component composed of leads connected at both ends of a fusible metal. The fusible metal is generally tin or tin alloy.

[0006] Customers of the above two types of products must use manual plug-in when using them, which has low work efficiency. In order to improve customer work efficiency, a shell plus potting process is adopted, which is larger in size and higher in cost.

[0007] Therefore, how to produce a varistor component with over-temperature protection that is compact, low-cost, mass-produced, and machine-pluggable by customers has become a technical problem that needs to be urgently solved in the industry. Summary of the invention

[0008] The purpose of the present invention is to provide a method for manufacturing a thermal protection type varistor component. The method can be used to mass produce a thermal protection type varistor component with a small size and low cost.

[0009] The technical solution of the present invention is a method for manufacturing a thermal protection type varistor component, wherein the varistor component comprises a chip type varistor chip, a pin bracket, a fusible metal, and an insulating plastic sealing layer, and the manufacturing method is as follows: 1) Make pin brackets, including upper middle pin brackets and lower pin brackets; 2) Place the pin bracket into the welding tooling mold; 3) Apply or apply solder to the lower pin bracket welding point; 4) Place the chip type pressure sensitive chip on the lower pin bracket; 5) Apply solder to the surface of the chip varistor or apply the solder that needs to be connected to the fusible metal; 6) Apply or apply solder to the upper middle pin bracket where the fusible metal needs to be connected; 7) Place the two ends of the fusible metal on the upper surface of the chip varistor and the welding point between the upper middle pin bracket and the chip; 8) Weld the chip type varistor, the pin bracket and the fusible metal together; 9) Use plastic encapsulation technology to encapsulate the welded components into an insulating plastic encapsulation layer; 10) Then the ribs are cut to form a thermal protection type varistor component product.

[0010] In the aforementioned method for manufacturing a thermal protection type varistor component, when the varistor component does not include a jumper, but the pin bracket includes an upper pin bracket, an upper middle pin bracket and a lower pin bracket, after the components welded together are encapsulated in an insulating plastic layer using a plastic encapsulation process, the upper pin bracket exposed outside the insulating plastic layer needs to be cut off before proceeding to the next step; When the varistor component further includes a jumper, and the pin bracket includes an upper pin bracket, an upper middle pin bracket and a lower pin bracket, the manufacturing method is as follows: 1) Make pin brackets, including upper pin brackets, upper middle pin brackets and lower pin brackets; 2) Place the pin bracket into the welding tooling mold; 3) Apply or apply solder to the lower pin bracket welding point; 4) Place the chip type pressure sensitive chip on the lower pin bracket; 5) Apply or apply solder to the surface of the chip varistor chip to connect the jumper and the fusible metal; 6) Apply or apply solder to the upper pin bracket and the upper middle pin bracket for connecting the jumper and the fusible metal; 7) Place the two ends of the jumper on the upper surface of the chip-type pressure-sensitive chip and the welding point between the upper pin bracket and it; 8) Place the two ends of the fusible metal on the upper surface of the chip varistor and the welding point between the upper middle pin bracket and the chip; 9) Weld the chip type varistor, pin bracket, jumper and fusible metal together; 10) Use plastic encapsulation technology to encapsulate the welded components into an insulating plastic encapsulation layer; 11) Then the ribs are cut to form a thermal protection type varistor component product.

[0011] In the aforementioned method for manufacturing a thermally protected varistor component, when the varistor component also includes a shell, after the components are welded, the welded components are loaded into an insulating shell, and then an insulating organic material is poured into the insulating shell, and after the insulating organic material is cured, a shell-enclosed thermally protected varistor component product is formed.

[0012] In the aforementioned method for manufacturing a thermal protection type varistor component, the chip-type varistor chip is a circular, square or other polygonal chip-type varistor chip.

[0013] In the aforementioned method for manufacturing a thermal protection type varistor component, starting from step 5) until the components are welded to form an assembly, this process adopts jumper technology.

[0014] In the aforementioned method for manufacturing a thermal protection type varistor component, the jumper is a flat sheet of conductive metal material.

[0015] In the aforementioned method for manufacturing a thermally protected varistor component, the fusible metal is a cylindrical, square column, or long flat strip structure made of tin or a tin alloy having a melting point of 120° C. to 300° C.

[0016] In the aforementioned method for manufacturing a heat-protected varistor component, the insulating plastic sealing layer is an insulating material that is a mixture of one or more of epoxy resin, liquid crystal polymer, polycarbonate, ABS plastic material, polystyrene, and phenolic resin.

[0017] In the aforementioned method for manufacturing a thermally protected varistor component, the insulating organic material is an insulating material of a mixture of one or more of epoxy resin, liquid crystal polymer, polycarbonate, ABS plastic material, polystyrene, and phenolic resin.

[0018] In the aforementioned method for manufacturing a thermal protection type varistor component, the fusing temperature C of the fusible metal> the welding temperature A when each component is welded> the plastic encapsulation temperature B.

[0019] The beneficial effects of the present invention are as follows: compared with the prior art, the method of the present invention can be used to assemble a chip-type varistor chip, a pin bracket, a jumper, a fusible metal and an insulating plastic layer together to form a thermal protection type varistor component. Compared with the existing varistor component, the varistor component has one end of the fusible metal connected to the suspended pin bracket and the other end connected to the varistor chip, eliminating the temperature fuse and the ceramic sheet, and the product can be made more miniaturized. The jumper technology process is used for the varistor component of this structure, and each component can be welded at one time, which is convenient for batch production, shortens the production cycle, and reduces the production cost; and the chip-type varistor chip, the pin bracket, the jumper, and the fusible metal can adopt the plastic packaging process, and the packaging process can be operated by machine, which improves the production efficiency. At the same time, by controlling the welding temperature in the production process, the welding temperature is lower than the fusing temperature of the fusible metal, so that the ceramic sheet does not need to be set in the whole structure; at the same time, by controlling the packaging temperature in the production process, the packaging temperature is lower than the welding temperature, avoiding the situation of welding point falling off, solder casting short circuit, etc. in the packaging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a top view of a three-pin varistor component according to the first embodiment of the present invention; Figure 2 yes Figure 1 A side cross-sectional view of Figure 3 is a top view of a two-pin varistor component according to a second embodiment of the present invention; Figure 4 is a top view of a two-pin varistor component according to a third embodiment of the present invention; Figure 5 It is a top view of a two-pin shell-mounted varistor component according to a fourth embodiment of the present invention.

[0021] Figure numerals: 10 - chip type varistor; 21 - upper pin bracket; 22 - upper middle pin bracket; 23 - lower pin bracket; 30 - jumper; 40 - fusible metal; 50 - insulating plastic sealing layer; 60 - shell; 70 - insulating organic material. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0023] TMOV products have two-pin usage and three-pin usage (with monitoring) when used. The two-pin and three-pin products of the same size can share the bracket and plastic encapsulation mold. If necessary, the two-pin product can also be made with a dedicated bracket and plastic encapsulation mold.

[0024] Embodiment 1 of the present invention: A TMOV-14D471K three-pin varistor component is manufactured by the method of the present invention, such as Figure 1 , Figure 2 As shown, the specific implementation is as follows: 1) Making a pin bracket corresponding to the 14D471K chip (chip-type pressure-sensitive chip 10), including an upper pin bracket 21, an upper middle pin bracket 22 and a lower pin bracket 23; 2) Place the pin bracket into the welding tooling mold; 3) Apply or apply solder to the lower pin bracket 23; 4) Place the 14D471K chip (chip-type pressure-sensitive chip 10) on the lower pin bracket 23; 5) Apply or apply solder to the upper surface of the 14D471K chip (chip varistor chip 10) for connecting the jumper 30 and the fusible metal 40; 6) Apply solder to the upper pin bracket 21 and the upper middle pin bracket 22 to connect the jumper 30 and the fusible metal 40; 7) Place the two ends of the jumper 30 on the welding point between the upper surface of the chip-type pressure-sensitive chip 10 and the upper pin bracket 21; 8) Place the two ends of the fusible metal 40 on the welding point between the upper surface of the chip type varistor chip 10 and the upper pin bracket 22; 9) Welding the chip type varistor chip 10, the pin bracket, the jumper 30, and the fusible metal 40 together; 10) The components welded together are encapsulated in an insulating plastic layer 50 using a plastic encapsulation process.

[0025] 11) Then cut the ribs to form a three-pin TMOV-14D471K product for over-temperature protection.

[0026] Embodiment 2 of the present invention: The method of the present invention is used to manufacture a TMOV-14D471K two-pin varistor component. This embodiment adopts a shared pin bracket and a plastic encapsulation mold solution, such as Figure 3 As shown, the specific implementation is as follows: 1) Making a pin bracket corresponding to the 14D471K chip (chip-type pressure-sensitive chip 10), including an upper pin bracket 21, an upper middle pin bracket 22 and a lower pin bracket 23; 2) Place the pin bracket into the welding tooling mold; 3) Apply or apply solder to the lower pin bracket 23; 4) Place the 14D471K chip (chip type pressure sensitive chip 10) on the lower pin bracket 23; 5) Apply solder to the fusible metal 40 to be connected on the upper surface of the chip varistor 10 or apply it; 6) Apply solder to the fusible metal 40 that needs to be connected on the upper middle pin bracket 22 points; 7) Place the two ends of the fusible metal 40 on the welding point between the upper surface of the chip type varistor chip 10 and the upper middle pin bracket 22; 8) Welding the chip type varistor chip 10, the lead bracket, and the fusible metal 40 together; 9) Encapsulating the welded components in an insulating plastic encapsulation layer 50 by using a plastic encapsulation process; 10) Cut off the upper pin bracket 21 exposed to the outside of the insulating plastic packaging layer 50; 11) Then cut the ribs to form a TMOV-14D471K two-pin product for over-temperature protection.

[0027] Embodiment 3 of the present invention: The method of the present invention is used to manufacture a TMOV-10D271K two-pin varistor component, using a dedicated two-pin bracket and a plastic packaging mold, such as Figure 4 As shown, the specific implementation is as follows: 1) Making a dedicated two-pin bracket corresponding to the 10D271K chip (chip-type pressure-sensitive chip 10), including an upper middle pin bracket 22 and a lower pin bracket 23; 2) Place the pin bracket into the welding tooling mold; 3) Apply or apply solder to the lower pin bracket 23; 4) Place the 10D271K chip (chip-type pressure-sensitive chip 10) on the lower pin bracket 23; 5) Apply solder to the fusible metal 40 to be connected on the upper surface of the 10D271K chip (chip varistor chip 10) or apply solder to the fusible metal 40 to be connected; 6) Apply solder to the fusible metal 40 that needs to be connected on the upper middle pin bracket 22 points; 7) Place the two ends of the fusible metal 40 on the welding point between the upper surface of the chip type varistor chip 10 and the upper pin bracket 22; 8) Welding the chip type varistor chip 10, the lead bracket, and the fusible metal 40 together; 9) Encapsulating the welded components in an insulating plastic encapsulation layer 50 by using a plastic encapsulation process; 10) Then cut the ribs to form a TMOV-10D271K two-pin product for over-temperature protection.

[0028] Embodiment 4 of the present invention: Since the size of the varistor chip is large and it is difficult to encapsulate it in plastic, a potting and shell encapsulation process can be used to encapsulate it. The method of the present invention is used to manufacture a TMOV-25D751K three-pin shell-mounted varistor component, such as Figure 5 As shown, the specific implementation is as follows: 1) Making a pin bracket corresponding to the 25D751K chip (chip-type pressure-sensitive chip 10), including an upper pin bracket 21, an upper middle pin bracket 22 and a lower pin bracket 23; 2) Place the pin bracket into the welding tooling mold; 3) Apply or apply solder to the lower pin bracket 23; 4) Place the 25D751K chip (chip type pressure sensitive chip 10) on the lower pin bracket 23; 5) Apply or apply solder to the upper surface of the 25D751K chip (chip varistor chip 10) for connecting the jumper 30 and the fusible metal 40; 6) Apply solder to the upper pin bracket 21 and the upper middle pin bracket 22 to connect the jumper 30 and the fusible metal 40; 7) Place the two ends of the jumper 30 on the upper surface of the chip-type pressure-sensitive chip 10 and the welding position of the upper pin bracket 21; 8) Place the two ends of the fusible metal 40 on the welding point between the upper surface of the chip type varistor chip 10 and the upper pin bracket 22; 9) Welding the chip type varistor chip 10, the pin bracket, the jumper 30, and the fusible metal 40 together; 10) Installing the welded components into the insulating housing 60; 11) Potting insulating organic material 70, after solidification, to form TMOV-25D751K three-pin shell product for over-temperature protection.

[0029] In the above embodiment, the specific structure and specific construction requirements of each component are as follows: The chip-type pressure-sensitive chip 10 is a circular, square or other polygonal chip-type pressure-sensitive chip with various structures, and is not limited to a certain structural form, and can adapt to different product structures.

[0030] Each embodiment starts from step 5) until each component is welded to form an assembly, and this process adopts the jumper technology process.

[0031] The jumper 30 is a flat sheet of conductive metal material, which is easy to process and connect with other components, and can reduce the thickness of the entire product, so that the product volume can be made smaller.

[0032] The fusible metal 40 is a cylindrical, square, or long flat strip structure made of tin or tin alloy with a melting point of 120°C to 300°C. When the temperature exceeds the melting temperature of the fusible metal, the fusible metal 40 melts, thereby providing the product with over-temperature protection.

[0033] The insulating plastic sealing layer 50 is an insulating material of one or more mixtures of epoxy resin, liquid crystal polymer, polycarbonate, ABS plastic material, polyethylene, phenolic resin, etc., to ensure good insulation performance.

[0034] The insulating organic material 70 is an insulating material of one or more mixtures of epoxy resin, liquid crystal polymer, polycarbonate, ABS plastic material, polyethylene, phenolic resin, etc., to ensure good insulation performance.

[0035] The temperature when the components are welded together to form an assembly is A, and the encapsulation temperature when the welded assembly is encapsulated in the insulating plastic encapsulation layer 50 by the plastic encapsulation process is B. The melting temperature C of the fusible metal 40 is greater than the welding temperature A and the plastic encapsulation temperature B. By controlling the welding temperature during the manufacturing process, the welding temperature is lower than the melting temperature of the fusible metal 40, so that the entire structure does not need to be provided with a ceramic sheet for heat insulation, ensuring that the fusible metal 40 will not be melted during the welding process; at the same time, by controlling the plastic encapsulation temperature during the manufacturing process, the plastic encapsulation temperature is lower than the welding temperature, avoiding the occurrence of welding point shedding / solder casting short circuit during the encapsulation process.

Claims

1. A method for manufacturing a thermal protection type varistor component, characterized in that: The varistor component comprises a varistor chip (10), a pin bracket, a fusible metal (40), and an insulating plastic sealing layer (50), and the manufacturing method thereof is as follows: 1) Making a pin bracket, including an upper middle pin bracket (22) and a lower pin bracket (23); 2) Place the pin bracket into the welding tooling mold; 3) Apply or apply solder to the welding point of the lower pin bracket (23); 4) placing the chip-type pressure-sensitive chip (10) on the lower pin support (23); 5) applying solder to the fusible metal (40) to be connected on the upper surface of the chip-type varistor (10); 6) Apply or apply solder to the fusible metal (40) to be connected on the upper middle pin bracket (22); 7) placing the two ends of the fusible metal (40) on the upper surface of the chip-type varistor (10) and the welding point between the upper middle pin bracket (22) and the chip; 8) welding the chip type varistor chip (10), the pin bracket, and the fusible metal (40) together; 9) Encapsulating the welded components into an insulating plastic encapsulation layer (50) using a plastic encapsulation process; 10) Then the ribs are cut to form a thermal protection type varistor component product.

2. The method for manufacturing a thermal protection type varistor component according to claim 1, characterized in that: When the varistor component does not include a jumper (30), but the pin bracket includes an upper pin bracket (21), an upper middle pin bracket (22), and a lower pin bracket (23), after the components welded together are encapsulated in an insulating plastic sealing layer (50) using a plastic sealing process, the upper pin bracket (21) exposed outside the insulating plastic sealing layer (50) needs to be cut off before proceeding to the next step; When the varistor component further includes a jumper (30), and the pin bracket includes an upper pin bracket (21), an upper middle pin bracket (22), and a lower pin bracket (23), the manufacturing method is as follows: 1) manufacturing a pin bracket, including an upper pin bracket (21), an upper middle pin bracket (22) and a lower pin bracket (23); 2) Place the pin bracket into the welding tooling mold; 3) Apply or apply solder to the welding point of the lower pin bracket (23); 4) placing the chip-type pressure-sensitive chip (10) on the lower pin support (23); 5) applying solder to the upper surface of the chip-type varistor (10) for connecting the jumper (30) and the fusible metal (40); 6) Apply or apply solder to the upper pin bracket (21) and the upper middle pin bracket (22) to connect the jumper (30) and the fusible metal (40); 7) placing the two ends of the jumper (30) on the upper surface of the chip-type pressure-sensitive chip (10) and the welding point between the upper pin bracket (21) and the chip; 8) placing the two ends of the fusible metal (40) on the upper surface of the chip-type varistor (10) and the welding point between the upper middle pin bracket (22) and the chip; 9) welding the chip-type varistor chip (10), the pin bracket, the jumper (30), and the fusible metal (40) together; 10) Encapsulating the welded components into an insulating plastic encapsulation layer (50) using a plastic encapsulation process; 11) Then the ribs are cut to form a thermal protection type varistor component product.

3. A method for manufacturing a thermal protection type varistor component according to claim 1 or 2, characterized in that: When the varistor component further includes a housing (60), after the components are welded, the welded components are installed in the insulating housing (60), and then an insulating organic material (70) is poured into the insulating housing (60), and after the insulating organic material (70) is cured, a housing-enclosed heat-protected varistor component product is formed.

4. The method for manufacturing a thermal protection type varistor component according to claim 1, characterized in that: The sheet-type pressure-sensitive chip (10) is a circular, square or other polygonal sheet-type pressure-sensitive chip.

5. A method for manufacturing a thermal protection type varistor component according to claim 1 or 2, characterized in that: Starting from step 5) until the individual components are welded to form an assembly, this process uses the jumper technology process.

6. The method for manufacturing a thermal protection type varistor component according to claim 2, characterized in that: The jumper sheet (30) is a flat sheet of conductive metal material.

7. The method for manufacturing a thermal protection type varistor component according to claim 1, characterized in that: The fusible metal (40) is a cylindrical, square column, or long flat strip structure made of tin or a tin alloy having a melting point of 120°C to 300°C.

8. The method for manufacturing a thermal protection type varistor component according to claim 1, characterized in that: The insulating plastic sealing layer (50) is an insulating material that is a mixture of one or more of epoxy resin, liquid crystal polymer, polycarbonate, ABS plastic material, polyethylene, and phenolic resin.

9. The method for manufacturing a thermal protection type varistor component according to claim 3, characterized in that: The insulating organic material (70) is an insulating material that is a mixture of one or more of epoxy resin, liquid crystal polymer, polycarbonate, ABS plastic material, polyethylene, and phenolic resin.

10. A method for manufacturing a thermal protection type varistor component according to claim 1 or 2, characterized in that: The fusing temperature C of the fusible metal (40)>the welding temperature A when each component is welded>the plastic sealing temperature B.

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