TW202034363A - Fuse resistor assembly and method of manufacturing the fuse resistor assembly - Google Patents

Abstract

Disclosed is a fuse resistor assembly including a first resistor and a second resistor which distribute applied currents or voltages and a fuse located between the first resistor and the second resistor and having one side coupled with the first resistor and the other side coupled with the second resistor to be connected to the first resistor and the second resistor in series. Here, the fuse includes a stick-shaped fuse rod and a fusible coating layer applied to a surface of the fuse rod and fuses due to overcurrents generated at the first resistor and the second resistor.

Description

Fuse resistor assembly and method for manufacturing fuse resistor assembly

[Cross-reference of related applications]

This application claims the priority and rights of Korean Patent Application No. 2019-0019917 filed on February 20, 2019, and the entire disclosure of the case is incorporated herein by reference.

The present invention relates to a fusing resistor assembly, and more specifically, to a fusing resistor assembly including a fuse existing between resistors and a method of manufacturing the same.

Generally speaking, micro fuses are installed at the power input terminals of electronic products such as televisions, video cassette recorders and the like to prevent circuit damage and damage by breaking the circuit when overcurrent flows in the circuit. The fire broke out at the base plate. The micro-fuse acts as a circuit breaker due to its fusing performance under abnormal conditions such as overload and the like.

In the case of fuses, copper with a relatively low specific resistance value and a relatively high temperature coefficient and melting point is used as the material for forming the fusible element layer, so that even when the rated normal current is changed to a high current of 10A or higher At this time, the fuse can still be blown stably. This is due to an overcurrent equal to or higher than the current while the high current flows stably through the fuse for a certain period of time. Therefore, the fuse is used in home appliances such as large televisions, large monitors, and the like instead of existing fuses.

However, the conventional fusing resistor assembly has a problem in that the fusing performance of the fuse is not constant according to the heating of the resistor, and it does not react sensitively to overcurrent.

The present invention aims to provide a fuse resistor assembly and a manufacturing method thereof. The fuse resistor assembly improves the fusing performance of the fuse by connecting the fuse in series between the resistors.

According to an aspect of the present invention, there is provided a fuse resistor assembly, which includes: a first resistor and a second resistor, which distribute the applied current or voltage; and a fuse, which is positioned between the first resistor and the first resistor Between the second resistors, there is one side coupled to the first resistor and the other side coupled to the second resistor to be connected in series to the first resistor and the second resistor. Here, the aforementioned fuse includes: a rod-shaped fuse rod; and a meltable coating layer, which is applied to the surface of the aforementioned fuse rod and is attributed to the heat generated at the aforementioned first resistor and the aforementioned second resistor. The current melts.

The foregoing first resistor may include: a first resistor bar; a first outer resistor cap coupled to one side of the foregoing first resistor bar; and a first inner resistor cap connected to the foregoing first resistor bar The other side is coupled; and a first resistance wire, which is assembled to close the first resistor bar and connect the first outer resistor cap to the first inner resistor cap. The foregoing second resistor may include: a second resistor bar; a second outer resistor cap coupled to one side of the foregoing second resistor bar; and a second inner resistor cap connected to the foregoing second resistor bar The other side is coupled; and a second resistance wire, which is assembled to close the second resistor bar and connect the second outer resistor cap to the second inner resistor cap.

The first inner resistor cap may include: a first resistor insertion groove having a groove configured to allow one side of the first resistor rod to be inserted and coupled to the other side of the first resistor rod; and a first The fuse insertion groove has a groove configured to allow its other side to be inserted and coupled to one side of the aforementioned fuse.

The second inner resistor cap may include: a second resistor insertion groove having a groove configured to allow one side of the second resistor rod to be inserted and coupled to the other side of the second resistor rod; and a second The fuse insertion groove has a groove configured to allow the other side of the fuse to be inserted and coupled to the other side of the fuse.

The meltable coating layer can be formed by coating the surface of the fuse rod with a tin component.

The meltable coating layer may include a trimming pattern, and the trimming pattern is formed to adjust the melting time caused by the overcurrent.

The aforementioned trimming pattern can be cut by one or more of different number of cutting points and cutting shapes.

The fuse resistor assembly may further include a component protection cover assembled to enclose the first resistor, the second resistor, and the fuse.

According to another aspect of the present invention, a method of manufacturing a fuse resistor assembly is provided. The foregoing method includes: forming a first resistor and a second resistor, which distribute the applied current or voltage; connecting a fuse in series between the first resistor and the second resistor, and the fuse is The overcurrent generated by the first resistor and the second resistor is fused; and the first resistor, the second resistor, and the fuse are sealed with a component protection cover. Here, one side of the fuse is insert-coupled to the first inner resistor cap of the first resistor, and the other side of the fuse is insert-coupled to the second inner resistor cap of the second resistor .

The foregoing connecting the fuse in series between the first resistor and the second resistor may include connecting the first resistor to the fuse in series, and the first resistor includes: a first resistor inserted A groove having a groove configured to allow one side to be inserted into the other side coupled to the first resistor bar; and a first fuse insertion groove having a groove configured to allow the other side of the first resistor rod Insert the coupling groove with one side of the aforementioned fuse.

The foregoing connecting the fuse in series to the first resistor and the second resistor may include connecting the second resistor to the fuse in series, and the second resistor includes: a second resistor inserted in A groove having a groove configured to allow one side to be coupled to the other side of the second resistor rod; and a second fuse insertion groove having a groove configured to allow the other side Insert the coupling groove with the other side of the aforementioned fuse.

The aforementioned fuse may include a meltable coating layer that is melted by overcurrent and formed on a rod-shaped fuse rod.

The meltable coating layer may include a trimming pattern, and the trimming pattern is formed to adjust the melting time caused by the overcurrent.

The aforementioned trimming pattern can be cut by one or more of different number of cutting points and cutting shapes.

Since the description of the present invention is only an embodiment for structural and functional description, the scope of the present invention should not be interpreted as being limited by the embodiments described herein. That is, since the embodiments can be variously changed and can have various shapes, the scope of the present invention should be understood to include equivalents that can embody its technical concept.

When it is stated that a component is "connected" to another component, it should be understood that one component can be directly connected to another component, but another component can exist in between. On the other hand, when it is stated that a component is "directly connected" to another component, it should be understood that no other component exists in between.

Unless otherwise defined, the terms used herein have the same meaning as generally understood by those who are familiar with the art. The terms defined in the general dictionary should be interpreted as consistent with the contextual meaning of the relevant technology and cannot be interpreted as an ideal or excessively formal meaning, unless clearly defined in the present invention.

1A is a perspective view illustrating a fuse resistor assembly 10 according to an embodiment of the present invention, and FIG. 1B is a longitudinal cross-sectional surface of the fuse resistor assembly shown in FIG. 1A (taken along A-A' The cross-section) cross-sectional view taken.

1A and 1B, the fuse resistor assembly 10 includes a first resistor 100, a second resistor 200, a fuse 300, and a component protection cover 400.

The first resistor 100 includes a conductive resistor part and restrains inrush current. In addition, the second resistor 200 also includes a conductive resistor component and restrains the inrush current.

2 is a reference view illustrating detailed components of the first resistor 100 or the second resistor 200.

2, the first resistor 100 includes a first resistor bar 102, a first outer resistor cap 104, a first inner resistor cap 106, and a first resistance wire.

The first resistor bar 102 may be formed of a ceramic material, and may include a cylindrical or prismatic shape.

The first outer resistor cap 104 is coupled to one side of the first resistor bar 102. The first outer resistor cap 104 can be inserted into and coupled to one end of the first resistor rod 102. The first outer resistor cap 104 may be a cap: it includes a unidirectional insertion groove G0 (for example, a circular groove or an angular groove) formed only in the one side, so that the first resistor rod 102 The one end can be inserted into it. The first outer resistor cap 104 may be formed of a conductive material.

At the same time, the first resistor outer lead 104-2 may be coupled to the other side of the first outer resistor cap 104 (that is, the outer side of the cap). The first resistor outer lead 104-2 is a conductive wire. The first resistor outer lead 104-2 may be connected to the first outer resistor cap 104 using methods such as spot welding, laser welding, welding and the like.

The first inner resistor cap 106 can be inserted into and coupled to the other end of the first resistor bar 102. For this purpose, the first inner resistor cap 106 may have a bidirectional groove structure (for example, a circular groove or an angular groove), and may include a first resistor insertion groove G1 and a first fuse insertion groove G2. The first resistor insertion groove G1 has a groove structure formed to be inserted and coupled to the other side of the first resistor bar 102, and the first fuse insertion groove G2 has a groove structure formed to be inserted and coupled to the fuse The groove structure on one side of 300. The first inner resistor cap 106 may be formed of a conductive material.

The first resistance wire 108 is a conductive wire that surrounds the first resistor bar 102 and connects the first outer resistor cap 104 to the first inner resistor cap 106. The first resistance wire 108 spirally surrounds the surface of the first resistor bar 102 and connects the first outer resistor cap 104 to the first inner resistor cap 106. The first resistance line 108 includes a resistor component that generates heat due to overcurrent. One end 108-1 of the first resistance line 108 is connected to one side of the first outer resistor cap 104, and the other end 108-2 of the first resistance line 108 is connected to one side of the first inner resistor cap 106.

Also, referring to FIG. 2, the second resistor 200 includes a second resistor bar 202, a second outer resistor cap 204, a second inner resistor cap 206 and a second resistance wire 208.

The second resistor bar 202 may be formed of a ceramic material including a shape such as a cylindrical shape or a prismatic shape.

The second outer resistor cap 204 includes a cap structure coupled to one side of the second resistor bar 202.

The second inner resistor cap 206 includes a cap structure coupled to the other side of the second resistor bar 202. For this purpose, the second inner resistor cap 206 may include: a second resistor insertion groove G1', which has a recess configured to allow one side thereof to be inserted and coupled to the other side of the second resistor rod 202 Groove; and the second fuse insertion groove G2', which has been configured to allow its other side to be inserted into the groove coupled to the other side of the fuse 300.

The second resistance wire 208 surrounds the second resistor bar 202 and connects the second outer resistor cap 204 to the second inner resistor cap 206. The second resistance line 208 may have a resistance value equal to the resistance value of the first resistance line 108 and may have a resistance value different from the resistance value of the first resistance line 108.

The second resistor bar 202 has a structure equal to or similar to that of the first resistor bar 102 of the first resistor 100, and the second outer resistor cap 204 has a structure equal to or similar to the first outer resistor cap 104 Structure. The second inner resistor cap 206 has a structure equal to or similar to the structure of the first inner resistor cap 106 of the first resistor 100, and the second resistance line 208 has a first resistance equal to or similar to the first resistor 100 The structure of the line 108 structure. Therefore, a detailed description of each component of the second resistor 200 will be omitted.

The fuse 300 is positioned between the first resistor 100 and the second resistor 200, electrically connects the first resistor 100 to the second resistor 200, and performs the function of a fusible body that is being destroyed by overcurrent. That is, the fuse 300 has one side coupled to the first resistor 100 and the other side coupled to the second resistor 200, is connected to the first resistor 100 and the second resistor 200 in series, and performs Destroy the function of the circuit connection caused by heat or overcurrent.

3 is a reference view illustrating the fuse 300 coupled between the first inner resistor cap 106 of the first resistor 100 and the second inner resistor cap 206 of the second resistor 200. 3, one side of the fuse 300 can be inserted into and coupled to the first inner resistor cap 106 of the first resistor 100, and the other side of the fuse 300 can be inserted into and coupled to the second resistor 200 of the second inner resistor cap 206.

The fuse 300 may include a rod-shaped fuse bar 302 and a meltable coating layer 304. The meltable coating layer 304 is applied to the surface of the fuse bar 302 and is formed by the first resistor 100 and the second resistor 200. The generated overcurrent melts.

The fuse bar 302 may include a cylindrical or prismatic shape, and may be formed of a ceramic material.

When an overvoltage or an overcurrent is applied to cause the first resistor 100 or the second resistor 200 to generate heat, the fusible coating layer 304 melts due to the heat and cuts off the electrical connection. The meltable coating layer 304 can be formed by coating the surface of the fuse rod 302 with a tin component. The fusible coating layer 304 may be, for example, a fusible body including a low melting point metal or alloy having a melting point at or below 450°C, for example, from tin (Sn), silver (Ag), antimony (Sb) , At least one element of indium (In), bismuth (Bi), aluminum (Al), zinc (Zn), copper (Cu), and nickel (Ni), but not limited to this.

The fusible coating layer 304 is a trimming pattern that is assembled to adjust the melting time caused by the overcurrent. The trimming pattern can be formed by laser cutting or diamond cutting. Here, the trimming pattern can be cut by one or more of different number of cutting points and cutting shapes. Here, the cutting shape may be a dot, linear, or spiral shape, or may be a combination thereof.

4 is a reference view illustrating a trimming pattern formed on the meltable coating layer 304 of the fuse 300 according to the present invention. FIG. 4A illustrates a point-shaped trimming pattern, and FIG. 4B illustrates a linear-shaped trimming pattern.

Depending on the number of cutting points or the difference in cutting shape, the trimming pattern can cause a difference in the melting time of the fusible coating layer 304 caused by overcurrent. The difference in the melting time of the meltable coating layer 304 according to the trimming pattern will be described with reference to FIGS. 5 to 7.

5 is a reference view illustrating an example of comparing the melting time based on the number of cut points, FIG. 6 is a reference view illustrating an embodiment of comparing the melting time based on the point shape in the cut shape, and FIG. 7 is a reference view illustrating the comparison based on the cut shape A reference view of another embodiment of the line shape comparing the melting time.

Referring to Figure 5, it can be seen that as the number of cutting points in the trimming pattern increases, the melting time gradually decreases. Also, referring to FIG. 6, it can be seen that as the cutting point in the cutting shape of the trimming pattern increases in the longitudinal direction, the melting time decreases. Also, referring to FIG. 7, it can be seen that as the length of the linear or spiral line in the cut shape of the trimming pattern increases, the melting time decreases. Therefore, it is possible to adjust the melting time of the fuse resistor assembly 10 caused by the overcurrent by selecting the trimming pattern of the fusible coating layer 304 according to the design purpose.

The component protection cover 400 seals the first resistor 100, the second resistor 200 and the fuse 300. The component protection cover 400 protects the surfaces of the first resistor 100, the second resistor 200, and the fuse 300. In addition, the component protection cover 400 serves as a cover assembled to insulate the current flowing through the first resistor 100, the second resistor 200, and the fuse 300 from the outside.

FIG. 8 is a flowchart illustrating an embodiment of a method of manufacturing a fuse resistor assembly according to the present invention.

First, a first resistor and a second resistor are formed, which distribute the applied current or voltage (S500). Here, the first resistor may include a first resistor bar, a first outer resistor cap coupled to one side of the first resistor bar, and a first inner resistor cap coupled to the other side of the first resistor bar. A resistor cap and a first resistance wire surrounding the first resistor bar and connecting the first outer resistor cap to the first inner resistor cap. Here, the first inner resistor cap may include: a first resistor insertion groove having a groove configured to allow one side thereof to be inserted and coupled to the other side of the first resistor rod; and a first The fuse insertion groove has a groove configured to allow its other side to be inserted and coupled to one side of the fuse. Furthermore, the second resistor may include a second resistor bar, a second external resistor cap coupled to one side of the second resistor bar, and a second internal resistor coupled to the other side of the second resistor bar A resistor cap and a second resistance wire surrounding the second resistor bar and connecting the second outer resistor cap to the second inner resistor cap. Here, the second inner resistor cap may include: a second resistor insertion groove having a groove configured to allow one side thereof to be inserted and coupled to the other side of the second resistor rod; and a second The fuse insertion groove has a groove configured to allow the other side of the fuse to be inserted and coupled to the other side of the fuse.

The process of forming the first resistor will be described as follows. After the first outer resistor cap and the first inner resistor cap are coupled to the two ends of the first resistor bar, the first resistor outer lead is coupled to one side of the first outer resistor cap. Then, the first resistance wire surrounds the first resistor bar and connects the first outer resistor cap to the first inner resistor cap. The process of forming the second resistor is equal to the process of forming the first resistor.

After operation S500, a fuse blown by the overcurrent generated by the first resistor and the second resistor is connected in series between the first resistor and the second resistor (S502). The fuse may be a rod-shaped fusible body including a low melting point metal or alloy, for example, at least one element from Sn, Ag, Sb, In, Bi, Al, Zn, Cu, and Ni. The fuse may include a ceramic tube, terminals formed at both ends of the ceramic tube, and a fusible body wire inserted in the ceramic tube. One side of the fuse can be inserted into the first fuse insertion groove coupled to the first resistor to be connected in series to the first fuse insertion groove, and the other side of the fuse can be inserted and coupled to the second resistor The second fuse insertion groove of the connector is connected to the second fuse insertion groove in series.

The fuse can be formed by coating a rod-shaped fuse rod with a meltable coating layer melted by overcurrent. The meltable coating layer is a trim pattern formed to adjust the melting time caused by the overcurrent and can be cut by one or more of different number of cutting points and cutting shapes.

After operation S502, the first resistor, the second resistor, and the fuse are sealed by the component protection cover (S504). The component protection cover performs an insulation function with respect to the current flowing through the first resistor, the second resistor and the fuse.

The fuse resistor assembly 10 according to the present invention has a structure in which a fuse corresponding to a fusible body is positioned between the resistors to connect two wire wound resistors in series. The performance of the fusing resistor assembly 10 according to the present invention can be seen by testing the thermal/electrical performance, such as reflow, surge, partial short circuit and the like.

9A to 9H are reference tables for explaining the performance test of the fuse resistor assembly according to an embodiment of the present invention, and FIG. 10 is a table comparing the results of the tests shown in FIGS. 9A to 9H.

9A to 9H and 10, the fuse resistor assembly 10 according to the present invention is injection molded using materials such as thermoplastic resin and thermosetting resin, so that the durability of the fusible body with respect to external heat can be achieved in the reflow process Provided while executing.

Furthermore, according to the present invention, the fusible body is positioned on the inner side compared to the existing injection molded product, so that the influence on the heat flowing in from the outside (the heat flowing in through the reflow wire) can be minimized. Also, due to the heat sink effect caused by the ceramic rods of the first resistor and the second resistor placed on both sides of the fuse, the heat close to the fuse is mainly caused by the first resistor and the first resistor. The second resistor is cut off, so that the influence of external heat can be minimized.

Also, since the fuse is positioned between the first resistor and the second resistor so that the fuse is heated by the first resistor and the second resistor at its two sides, the fusing time is comparable to that of only one resistor. The provided knowledge status can be reduced compared to that.

In addition, since it is possible to minimize the size of the resistor, the surge performance can be enhanced while the first resistor 100 and the second resistor 200 are wound.

According to the embodiment of the present invention, since the fuse is connected to the resistor while the fuse is connected between the two resistors, the radiant heat generated at the resistor is effectively transmitted to the fuse, so that the fuse's fusing performance It can react sensitively according to the overcurrent flowing through the resistor. Therefore, the circuit element can be properly protected from the load caused by the overcurrent.

In particular, according to the present invention, a fuse including a fuse bar coated with a fusible body is connected in series between the resistors, so that the durability of the fused resistor assembly can be increased. Therefore, regardless of external impact, damage to the fusing resistor assembly can be minimized, and at the same time, the fusing performance of the fuse caused by the overcurrent can be accurately implemented according to the trimming pattern.

Although exemplary embodiments of the present invention have been described above and illustrated in the drawings, the present invention is not limited to the specific embodiments described above, and various modifications can be made by those who are generally familiar with the art. Depart from the essence of the present invention claimed by the scope of patent application and should not be understood as being separated from the technical concept or prospect of the present invention.

10: Fuse resistor assembly 100: first resistor 102: first resistor bar 104: The first outer resistor cap 104-2: Outer lead of the first resistor 106: first inner resistor cap 108: The first resistance line 108-1: end 108-2: end 200: second resistor 202: second resistor bar 204: second outer resistor cap 206: second inner resistor cap 208: second resistance wire 300: Fuse 302: (stick-shaped) fuse rod 304: Fusible coating layer 400: Component protection cover G0: One-way insertion groove G1: The first resistor is inserted into the groove G1’: Insert the second resistor into the groove G2: The first fuse is inserted into the groove G2’: The second fuse is inserted into the groove S500: Operation S502: Operation S504: Operation

By describing the exemplary embodiments of the present invention in detail with reference to the accompanying drawings, the above and other objectives, features and advantages of the present invention will become more apparent to those skilled in the art.

Fig. 1A is a perspective view of a fuse resistor assembly according to an embodiment of the present invention.

Fig. 1B is a cross-sectional view of the fusing resistor assembly shown in Fig. 1A taken along its longitudinal cross-sectional surface (a cross-section taken along A-A').

Fig. 2 is a reference view illustrating detailed components of the first resistor or the second resistor.

3 is a reference view illustrating the fuse coupled between the first resistor and the second resistor.

4A and 4B are reference views illustrating the trimming pattern formed on the meltable coating layer 304 of the fuse 300 according to the present invention.

FIG. 5 is a reference view illustrating an example of comparing the melting time according to the number of cutting points.

6 is a reference view illustrating an embodiment of comparing the melting time according to the point shape in the cut shape.

FIG. 7 is a reference view illustrating another embodiment of comparing the melting time according to the line shape among the cut shapes.

FIG. 8 is a flowchart illustrating an embodiment of a method of manufacturing a fuse resistor assembly according to the present invention.

9A to 9H are reference tables for explaining the performance test of the fuse resistor assembly according to an embodiment of the present invention.

Figure 10 is a table comparing the results of the tests shown in Figures 9A to 9H.

10: Fuse resistor assembly

Claims (14)

A fuse resistor assembly, which includes: The first resistor and the second resistor, the aforementioned first resistor and the second resistor distribute the applied current or voltage; and The fuse is positioned between the first resistor and the second resistor, and has one side coupled to the first resistor and the other side coupled to the second resistor to be connected in series To the aforementioned first resistor and the aforementioned second resistor; The aforementioned fuses include: Stick-shaped fuse rod; and The meltable coating layer is applied to the surface of the fuse bar and melted due to the overcurrent generated at the first resistor and the second resistor. The fuse resistor assembly described in claim 1, wherein the aforementioned first resistor includes: First resistor bar; The first outer resistor cap, which is coupled to one side of the aforementioned first resistor rod; The first inner resistor cap is coupled to the other side of the aforementioned first resistor rod; and A first resistance wire which is assembled to enclose the first resistor rod and connect the first outer resistor cap to the first inner resistor cap, and The aforementioned second resistor includes: Second resistor rod; A second outer resistor cap, which is coupled to one side of the aforementioned second resistor rod; The second inner resistor cap is coupled to the other side of the aforementioned second resistor rod; and The second resistance wire is assembled to enclose the second resistor rod and connect the second outer resistor cap to the second inner resistor cap. The fuse resistor assembly described in claim 2, wherein the aforementioned first inner resistor cap includes: The first resistor insertion groove has a groove configured to allow one side to be inserted into the other side of the first resistor rod; and The first fuse insertion groove has a groove configured to allow its other side to be inserted and coupled to one side of the aforementioned fuse. The fuse resistor assembly described in claim 2, wherein the aforementioned second inner resistor cap includes: The second resistor insertion groove has a groove that is configured to allow one side to be inserted and coupled to the other side of the second resistor rod; and The second fuse insertion groove has a groove configured to allow the other side of the fuse to be inserted and coupled to the other side of the fuse. The fuse resistor assembly according to claim 1, wherein the fusible coating layer is formed by coating the surface of the fuse rod with a tin component. The fuse resistor assembly according to claim 1, wherein the fusible coating layer includes a trim pattern, and the trim pattern is formed to adjust the melting time caused by the overcurrent. The fusing resistor assembly according to claim 6, wherein the trimming pattern is cut by one or more of different numbers of cutting points and cutting shapes. The fuse resistor assembly described in claim 1, which further includes a component protection cover assembled to enclose the first resistor, the second resistor, and the fuse. A method of manufacturing a fuse resistor assembly, the aforementioned method includes the following steps: Form a first resistor and a second resistor, which distribute the applied current or voltage; Connecting a fuse in series between the first resistor and the second resistor, and the fuse is blown by the overcurrent generated by the first resistor and the second resistor; and Enclose the aforementioned first resistor, the aforementioned second resistor and the aforementioned fuse with a component protection cover; One side of the fuse is insert-coupled with the first inner resistor cap of the first resistor, and the other side of the fuse is insert-coupled with the second inner resistor cap of the second resistor. The method according to claim 9, wherein the connecting the fuse in series to the first resistor and the second resistor includes connecting the first resistor to the fuse in series, and the first The resistor includes: a first resistor insertion groove, which has a groove that is configured to allow one side to be inserted and coupled to the other side of the first resistor rod; and a first fuse insertion groove, which has It is assembled to allow the other side of the fuse to be inserted into the coupling groove. The method according to claim 9, wherein the connecting the fuse in series to the first resistor and the second resistor includes connecting the second resistor to the fuse in series, and the second The resistor includes: a second resistor insertion groove, which has a groove that is configured to allow one side to be inserted and coupled to the other side of the second resistor rod; and a second fuse insertion groove, which has It is assembled to allow the other side of the fuse to be inserted into the coupling groove. The method according to claim 9, wherein the fuse includes a meltable coating layer that is melted by an overcurrent and formed on a rod-shaped fuse rod. The method according to claim 12, wherein the meltable coating layer includes a trimming pattern, and the trimming pattern is formed to adjust the melting time caused by the overcurrent. The method described in claim 11, wherein the trimming pattern is cut by one or more of different numbers of cutting points and cutting shapes.

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