WO2019000306A1

WO2019000306A1 - Anti-surge wire wound low temperature fuse resistor and manufacturing method thereof

Info

Publication number: WO2019000306A1
Application number: PCT/CN2017/090733
Authority: WO
Inventors: Shang-Yo Lee
Original assignee: Lee Shang Yo
Priority date: 2017-06-29
Filing date: 2017-06-29
Publication date: 2019-01-03
Also published as: CN110622260B; EP3646354A4; JP6836669B2; JP2020526042A; EP3646354A1; CN110622260B8; KR20200024258A; CN110622260A

Abstract

A fuse resistor includes an insulative rod, a first winding wire, a second winding wire and a connection wire. The insulative rod has a first end and a second end. The first winding wire wounds the insulative rod from the first end, and one end of the first winding wire is welded on a first cap. The second winding wire wounds the insulative rod from the second end, and one end of the second winding wire is welded on a second cap. The connection wire is disposed between the first winding wire and the second winding wire. The melting point of the connection wire is lower than the melting point of the first winding wire and the second winding wire. The first winding wire and the second winding wire are disconnected from each other, and electrically connected through the connection wire. The fuse resistor further includes a first electrical cover layer electrically connecting the end of the first winding wire to the first cap, and a second electrical cover layer electrically connecting the end of the second winding wire to the second cap, for enhancing fixing of the first winding wire and the second winding wire and increasing anti-surge effect.

Description

ANTI-SURGE WIRE WOUND LOW TEMPERATURE FUSE RESISTOR AND MANUFACTURING METHOD THEREOF

TECHNICAL FIELD

The present disclosure relates to a fuse resistor and a method for fabricating the same, and more particularly, to an anti-surge wire wound low temperature fuse resistor and a method for fabricating the same.

DISCUSSION OF THE BACKGROUND

When a circuit is operated normally, a fuse resistor performs as a fixed resistor. While working current exceeds rated current, the resistor blows due to overheating so as to protect the circuit. In general, a fuse temperature of a wire wound fuse resistor is a melting point of its wire. However, based on considering resistance and other electrical properties, the wire material of the conventional fuse resistor is essentially made of an alloy with a high melting point. The fuse temperature of the wire is too high, and there is a procedure of glowing red. The procedure of glowing red may burn and destroy circuits and other components, and thus effect of circuit protection is affected.

SUMMARY

One aspect of the present disclosure provides an anti-surge wire wound low temperature fuse resistor.

A fuse resistor according to some embodiments of the present disclosure includes an insulative rod, a first winding wire, a second winding wire and a connection wire. The insulative rod has a first end and a second end. The first winding wire winds the insulative rod from the first end of the insulative rod. The second winding wire winds the insulative rod from the second end of the insulative rod. The connection wire is disposed between the first winding wire and the second winding wire, wherein a melting temperature of the connection wire is lower than that of the first winding wire and that of the second winding wire, and the first winding wire and the second winding wire are separated from each other and electrically connected via the connection wire.

In some embodiments, the fuse resistor further includes a first insulating layer covering the first winding wire and the second winding wire, wherein the first insulating layer has an opening exposing a portion of the insulative rod.

In some embodiments, a material of the first insulating layer includes epoxy resin, a silicone non-flammable paint or an enamel paint.

In some embodiments, the opening includes a slot opening surrounding the insulative rod and partially exposing the insulative rod.

In some embodiments, the opening includes a dot opening partially exposing the insulative rod.

In some embodiments, the connection wire is in contact with the first winding wire and the second winding wire through the opening of the first insulating layer.

In some embodiments, the fuse resistor further includes a second insulating layer covering the first insulating layer and the connection wire, and filling into the opening of the first insulating layer.

In some embodiments, a material of the second insulating layer includes epoxy resin, a silicone non-flammable paint or an enamel paint.

In some embodiments, the fuse resistor further includes a first cap and a second cap, wherein the first cap is electrically welded on an end of the first winding wire from the first end of the insulative rod, and the second cap is electrically welded on an end of the second winding wire from the second end of the insulative rod.

In some embodiments, the fuse resistor further includes a first electrical cover layer electrically connecting an end of the first winding wire to the first cap, and a second electrical cover layer electrically connecting an end of the second winding wire to the second cap.

In some embodiments, materials of the first electrical cover layer and the second electrical cover layer respectively include tin, copper, iron, silver, nickel or an alloy thereof.

In some embodiments, thicknesses of the first electrical cover layer and the second electrical cover layer are between 1 micrometer and 20 micrometers, respectively.

A method for fabricating a fuse resistor according to some embodiments of the present disclosure includes the following steps: providing an insulative rod； winding a wire on the insulative rod； cutting off the wire to form a first winding wire and a second winding wire separated from each other； and forming a connection wire for electrically connecting the first winding wire to the second winding wire, wherein a melting point of the connection wire is lower than those of the first winding wire and the second winding wire.

In some embodiments, the method further includes: forming a first insulating layer on the insulative rod and the wire before cutting off the wire； and forming opening in the first insulating layer and cutting off the wire.

In some embodiments, the method further includes: forming a second insulating layer for covering the first insulating layer and the connection wire and filling into the opening of the first insulating layer.

In some embodiments, the method further includes: covering a first cap on a first end of the insulative rod, and covering a second cap on a second end of the insulative rod.

In some embodiments, the method further includes: electrically welding one end of the wire on the first cap, and electrically welding the other end of the wire on the second cap.

In some embodiments, the method further includes: electrically connecting an end of the first winding wire to the first cap by using a first electrical cover layer, and electrically connecting an end of the second winding wire to the second cap by using a second electrical cover layer.

In some embodiments, the first electrical cover layer, the second electrical cover layer and the connection wire are formed together by the same process.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. Please note that in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

Figure 1 is a schematic view showing a fuse resistor in accordance with an embodiment of the present disclosure.

Figures 2 to 5 are schematic views showing a method for fabricating a fuse resistor in accordance with an embodiment of the present disclosure.

Figure 6 is a schematic view showing a fuse resistor in accordance with another embodiment of the present disclosure.

Figures 7 to 9 are schematic views showing a method for fabricating a fuse resistor in accordance with another embodiment of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of elements and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath” , “below” , “lower” , “above” , “upper” , “on” and the like, may be used herein for ease of description to describe one element or feature’s relationship to another element (s) or feature (s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Please refer to Figure 1. Figure 1 is a schematic view showing a fuse resistor in accordance with an embodiment of the present disclosure. As shown in Figure 1, the fuse resistor 1 of the present embodiment includes an insulative rod 10, a first winding wire 22, a second winding wire 24 and a connection wire 26. The insulating wire 10 has a first end 101 and a second end 102. In the present embodiment, the insulative rod 10 can include a ceramic rod, but the material of the insulative rod 10 is not limited to ceramic material, and any insulating material such as a glass fiber capable of achieving the purpose of the present disclosure can be used. In addition, in the present embodiment, the shape of the insulative rod 10 is, but not limited to, a cylindrical shape.

The insulative rod 10 is wound by the first winding wire 22 from a first end 101, and wound by the second winding wire 24 from a second end 102, wherein the first winding wire 22 and the second winding wire 24 are not directly connected but have a gap therebetween. In some embodiments, the insulative rod 10 is wound by the first winding wire 22 and the second winding wire 24 in a spiral-wound manner. In some embodiments, the gap between the first winding wire 22 and the second winding wire 24 is between about 0.05 mm and about 2 mm. The connection wire 26 is disposed between the first winding wire 22 and the second winding wire 24, and has a length slightly more than the gap between the first winding wire 22 and the second winding wire 24 for connecting the first winding wire 22 and the second winding wire 24. The melting point of the connection wire 26 is lower than the melting points of the first winding wire 22 and the second winding wire 24, and the first winding wire 22 and the second winding wire 24 are separated from each other and electrically connected by the connection wire 26.

In the present embodiment, materials of the first winding wire 22 and the second winding wire 24 can include or can be selected from the materials having higher melting point than the connection wire 26. For example, the melting points of the first winding wire 22 and the second winding wire 24 are between about 800℃ and about 1500℃, and the melting point of the connection wire 26 can be lower than about 500℃or lower than 300℃, and can be, but not limited to, about 200℃ to about 300℃. The materials of the first winding wire 22, the second winding wire 24 and the connection wire 26 can be determined according to the electrical specification and the safety specification of the resistor. In some embodiments, the materials of the first winding wire 22 and the second winding wire 24 can include or can be selected from nickel-copper alloy or other suitable conductive metal or alloy materials with high melting points, and the material of the connection wire 26 can include or can be selected from tin, copper, other connective metals or alloy materials with lower melting points. By the above configuration, when the working current of the fuse resistor 2 in the present embodiment exceeds rated current, the connection wire 26 having a lower melting point has a lower fusing temperature and a faster fusing speed, such that the connection wire 26 would be fused first to protect the circuit. In addition, it is noted that under the normal operation, the operation temperature of the fuse resistor 1 is under about 70℃, and thus the connection wire 26 having the lower melting point would not affect the normal operation of the fuse resistor 1.

In some embodiments, the fuse resistor 1 can further include a first insulating layer 12 covering the first winding wire 22 and the second winding wire 24. The first insulating layer 12 has an opening 12S exposing a portion of the insulative rod 10. In some embodiments, the material of the first insulating layer 12 can include or can be selected from an insulating paint such as epoxy resin, or other insulating materials. In some embodiments, the connection wire 26 is in contact with the first winding wire 22 and the second winding wire 24 via the opening 12S of the first insulating layer 12. In some embodiments, the opening 12S of the first insulating layer 12 may include a slot opening, which surrounds the insulative rod 10 and partially exposes the insulative rod 10. In some embodiments, a width of the slot opening of the first insulating layer 12 is between, but not limited to, about 0.05 mm and 2 mm.

In some embodiments, the fuse resistor 1 can further include a second insulating layer 14 covering the first insulating layer 12 and the connection layer 26, and filling the opening 12S of the first insulating layer 12. In some embodiments, the material of the second insulating layer 14 can include or can be selected from an insulating paint such as epoxy resin, a silicone non-flammable paint, an enamel paint or other insulating materials.

In some embodiments, the fuse resistor 1 can further include a first cap 32 and a second cap 34. The first cap 32 covers the first end 101 of the insulative rod 10 and is connected to the first winding wire 22, and the second cap 34 covers the second end 102 of the insulative rod 10 and is connected to the second winding wire 24. In some embodiment, the materials of the first cap 32 and the second cap 34 can include iron, steel, aluminum, copper, other metals, an alloy or a graphite material. In some embodiments, one end of the first winding wire 22 can be welded first on the first cap 32, and one end of the second winding wire 24 can be welded first on the second cap 34. In some embodiments, the fuse resistor 1 can further include a first electrical cover layer 361 for electrically connecting one end of the first winding wire 22 to the first cap 32, and a second electrical cover layer 362 for electrically connecting one end of the second winding wire 24 to the second cap 34. In some embodiments, the materials of the first electrical cover layer 361 and the second electrical cover layer 362 can include, but not limited to, tin, copper, iron, silver, nickel or other alloys. In some embodiments, the first electrical cover layer 361 and the second electrical cover layer 362 can be formed by, but not limited to, electroplating. In some embodiments, the first electrical cover layer 361, the second electrical cover layer 362 and the connection wire 26 can be formed together by the same process to simplify the fabrication procedure. In some embodiments, the thicknesses of the first electrical cover layer 361 and the second electrical cover layer 362 are, but not limited to, between about 1 micrometer and about 20 micrometers, respectively. Under a surge shock situation, about more than 90％of occurrence that the conventional wire wound resistor breaks occurs at the solder point between the wire and the cap, resulting in an open circuit failure. Therefore, the first electrical cover layer 361 and the second electrical cover layer 362 can be used respectively for reinforcing the welding portion of the first winding wire 22 and the second winding wire 24, so as to enhance firmness of the welding portion, reduce the production failure rate and even increase reliability of welding. The welding firmness of the first winding wire 22 and the second winding wire 24 can be ensured by the first electrical cover layer 361 and the second electrical cover layer 362, such that the anti-surge effect of the fuse resistor 1 can be increased.

In some embodiments, the fuse resistor 1 can further include a first conductive line 42 extending outwards from the first cap 32 and electrically connected to the first cap 32, and a second conductive line 44 extending outwards from the second cap 34 and electrically connected to the second cap 34. The first conductive line 42 and the second conductive line 44 can be electrically connected to an external circuit, for example, a printed circuit board.

Please refer to Table 1. The fusing test results of the fuse resistors in comparative embodiments and embodiments of the present disclosure are listed in Table 1.

Table 1

In the fusing tests shown in Table 1, the fuse resistor in the comparative embodiment and the fuse resistor in the embodiment of the present disclosure have the same resistance value, i.e. 1Ω, and the same power, i.e. 2 W, wherein the first winding wire and the second winding wire of the fuse resistor in the comparative embodiment are directly connected, and the first winding wire and the second winding wire of the fuse resistor in the embodiment of the present disclosure are electrically connected via the connection wire with the low melting point. For example, the material of the connection wire can be tin, and formed by electroplating. As shown in Table 1, the errors of the resistance values of the fuse resistors in the comparative embodiment and the embodiment of the present disclosure are both in an acceptable range (±5％) , and in the condition that the fusing power is set as 40 times, the fusing time and the fusing temperature of the fuse resistor in the embodiment of the present disclosure are both lower than those of the fuse resistor in the comparative embodiment, proving that the fuse resistor in the embodiment of the present disclosure effectively enhances the protection effect to the circuit.

Please refer to Figures 2, 3, 4 and 5. Figures 2 to 5 are schematic views showing a method for fabricating a fuse resistor in accordance with an embodiment of the present disclosure. As shown in Figure 2, an insulative rod 10 is provided. The insulative rod 10 has a first end 101 and a second end 102. Subsequently, the insulative rod 10 is wound by a wire 21. In some embodiments, a first cap 32 and a second cap 34 can be formed at two sides of the insulative rod 10, and a first conductive line 42 and a second conductive line 44 can be formed at outer sides of the first cap 32 and the second cap 34 to extend outwards. In some embodiments, two ends of the wire 21 can be welded on the first cap 32 and the second cap 34 by welding. For example, one end of the wire 21 can be welded on the first cap 32 first, then the insulative rod 10 is wounded by the wire 21, and other end of the wire 21 is welded on the second cap 34.

As shown in Figure 3, a first insulating layer 12 is formed on the insulative rod 10 and the wire 21. As shown in Figure 4, subsequently, an opening 12S is formed in the first insulating layer 12, and the wire 21 is cut off, so as to form a first winding wire 22 and a second winding wire 24 separated from each other. In some embodiments, the opening 12S of the first insulating layer 12 is a slot opening, which surrounds the insulative rod 10 and partially exposes the insulative rod 10. In some embodiments, the formation of the slot opening of the first insulating layer 12 and the formation of cutting the wire 21 can be implemented simultaneously. In some embodiments, for example, a cutting tool can be used for forming the slot opening in the first insulating layer 12 and cutting off the wire 21. As shown in Figure 5, a connection wire 26 is formed for electrically connecting the first winding wire 22 to the second winding wire 24. In some embodiments, the connection wire 26 can be formed by electroplating, being immersed in a tin bath or other suitable processes. In some embodiments, in order to reinforce firmness of the welding points between the first winding wire 22 and the first cap 32 and between the second winding wire 24 and the second cap 34, a first electrical cover layer 361 can be formed for electrically connecting one end of the first winding wire 22 to the first cap 32 (by electroplating, for example) , and a second electrical cover layer 362 can be formed for electrically connecting one end of the second winding wire 24 to the second cap 34 (by electroplating, for example) , such that the welding firmness is enhanced. As shown in Figure 1, a second insulating layer 14 is then formed to cover the first insulating layer 12 and the connection wire 26 and fill into the opening 12S in the first insulting layer 12, such that a fuse resistor 1 of the present disclosure is formed.

The fuse resistor and the manufacturing method of the present disclosure are not limited to the above-mentioned embodiments, and may have other different embodiments. To simplify the description and for the convenience of comparison between each of the embodiments of the present disclosure, the identical components in each of the following embodiments are marked with identical numerals. For making it easier to compare the difference between the embodiments, the following description will detail the dissimilarities among different embodiments and the identical features will not be redundantly described.

Please refer to Figure 6. Figure 6 is a schematic view showing a fuse resistor in accordance with another embodiment of the present disclosure. In contrast to the fuse resistor 1 of Figure 1, the opening 12S of the first insulating layer 12 of the fuse resistor 2 includes a dot opening, which partially exposes the insulative rod 10. In some embodiments, the shape of the dot opening may include any regular or irregular geometric shape. In some embodiments, a width or a diameter of the dot opening of the first insulating layer 12 is between, but not limited to, about 0.05 mm and 2 mm. In the present embodiment, the material of the first insulating layer 12 can include or can be selected from an insulating paint such as epoxy resin, a silicone non-flammable paint, an enamel paint or other insulating materials. The connection wire 26 is in contact with the first winding wire 22 and the second winding wire 24 via the opening 12S of the first insulating layer 12. Furthermore, the second insulating layer 14 covers the first insulating layer 12 and the connection layer 26, and fills the opening 12S of the first insulating layer 12. In the present embodiment, the material of the second insulating layer 14 can include or can be selected from an insulating paint such as epoxy resin, a silicone non-flammable paint, an enamel paint or other insulating materials. The locations, connections, materials and other characteristics of components of the fuse resistor 2 such as the insulative rod 10, the first winding wire 22, the second winding wire 24, the connection layer 26, the first cap 32, the second cap 34, the first electrical cover layer 361, the second electrical cover layer 362, the first conductive line 42 and the second conductive line 44 may be similar to that of the fuse resistor 1 of Figure 1, and thus are not redundantly described.

Please refer to Figures 7, 8 and 9. Figures 7 to 9 are schematic views showing a method for fabricating a fuse resistor in accordance with an embodiment of the present disclosure. As shown in Figure 2, an insulative rod 10 is provided. The insulative rod 10 has a first end 101 and a second end 102. Subsequently, the insulative rod 10 is wound by a wire 21. In some embodiments, a first cap 32 and a second cap 34 can be formed at two sides of the insulative rod 10, and a first conductive line 42 and a second conductive line 44 can be formed at outer sides of the first cap 32 and the second cap 34 to extend outwards. In some embodiments, two ends of the wire 21 can be welded on the first cap 32 and the second cap 34 by welding. For example, one end of the wire 21 can be welded on the first cap 32 first, then the insulative rod 10 is wounded by the wire 21, and other end of the wire 21 is welded on the second cap 34. Subsequently, a first insulating layer 12 is formed on the insulative rod 10 and the wire 21.

As shown in Figure 8, subsequently, an opening 12S is formed in the first insulating layer 12, and the wire 21 is cut off, so as to form a first winding wire 22 and a second winding wire 24 separated from each other. In some embodiments, the opening 12S of the first insulating layer 12 is a dot opening, which partially exposes the insulative rod 10. In some embodiments, the formation of the dot opening of the first insulating layer 12 and the formation of cutting the wire 21 can be implemented simultaneously. In some embodiments, for example, a cutting tool can be used for forming the dot opening in the first insulating layer 12 and cutting off the wire 21. As shown in Figure 9, a connection wire 26 is formed in the dot opening for electrically connecting the first winding wire 22 to the second winding wire 24. In some embodiments, the connection wire 26 can be formed by electroplating, being immersed in a tin bath or other suitable processes. In some embodiments, in order to reinforce firmness of the welding points between the first winding wire 22 and the first cap 32 and between the second winding wire 24 and the second cap 34, a first electrical cover layer 361 can be formed for electrically connecting one end of the first winding wire 22 to the first cap 32 (by electroplating, for example) , and a second electrical cover layer 362 can be formed for electrically connecting one end of the second winding wire 24 to the second cap 34 (by electroplating, for example) , such that the welding firmness is enhanced. As shown in Figure 6, a second insulating layer 14 is then formed to cover the first insulating layer 12 and the connection wire 26 and fill into the opening 12S in the first insulting layer 12, such that a fuse resistor 2 of the present disclosure is formed.

In the fuse resistor of the present disclosure, the first winding wire and the second winding wire is connected by the connection wire, such that the fusing temperature and the fusing speed of the fuse resistor are well controlled, and the application range and safety of the fuse resistor are improved. In addition, in the fuse resistor of the present disclosure, the electrical cover layer is used for reinforcing welding points between the wire and the cap, so as to enhance welding firmness, avoid looseness of wire and reduce production failure. Hence, the fuse resistor of the present disclosure has the failure rate of surge-resisting welding point lower than 0.1 ppm. In the present disclosure, the anti-surge effect of the fuse resistor is improved, such that the fuse resistor of the present disclosure can be applied in anti-surge circuits, circuits of a spark plug and an ignition system of a vehicle.

The foregoing outlines structures of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.

Claims

A fuse resistor, comprising:

an insulative rod, having a first end and a second end；

a first winding wire, winding the insulative rod from the first end of the insulative rod；

a second winding wire, winding the insulative rod from the second end of the insulative rod； and

a connection wire, disposed between the first winding wire and the second winding wire, wherein a melting temperature of the connection wire is lower than those of the first winding wire and the second winding wire, and the first winding wire and the second winding wire are separated from each other and electrically connected via the connection wire.
The fuse resistor of claim 1, further comprising a first insulating layer covering the first winding wire and the second winding wire, wherein the first insulating layer has an opening exposing a portion of the insulative rod.
The fuse resistor of claim 2, wherein a material of the first insulating layer comprises epoxy resin, a silicone non-flammable paint or an enamel paint.
The fuse resistor of claim 2, wherein the opening includes a slot opening surrounding the insulative rod and partially exposing the insulative rod.
The fuse resistor of claim 2, wherein the opening includes a dot opening partially exposing the insulative rod.
The fuse resistor of claim 2, wherein the connection wire is in contact with the first winding wire and the second winding wire through the opening of the first insulating layer.
The fuse resistor of claim 6, further comprising a second insulating layer covering the first insulating layer and the connection wire, and filling into the opening of the first insulating layer.
The fuse resistor of claim 7, wherein a material of the second insulating layer comprises epoxy resin, a silicone non-flammable paint or an enamel paint.
The fuse resistor of claim 1, further comprising a first cap and a second cap, wherein the first cap is electrically welded on an end of the first winding wire from the first end of the insulative rod, and the second cap is electrically welded on an end of the second winding wire from the second end of the insulative rod.
The fuse resistor of claim 9, further comprising a first electrical cover layer electrically connecting an end of the first winding wire to the first cap, and a second electrical cover layer electrically connecting an end of the second winding wire to the second cap.
The fuse resistor of claim 10, wherein materials of the first electrical cover layer and the second electrical cover layer respectively comprise tin, copper, iron, silver, nickel or an alloy thereof.
The fuse resistor of claim 10, wherein thicknesses of the first electrical cover layer and the second electrical cover layer are between 1 micrometer and 20 micrometers, respectively.
A method for fabricating a fuse resistor, comprising:

providing an insulative rod；

winding a wire on the insulative rod；

cutting off the wire to form a first winding wire and a second winding wire separated from each other； and

forming a connection wire for electrically connecting the first winding wire to the second winding wire, wherein a melting point of the connection wire is lower than those of the first winding wire and the second winding wire.
The method of claim 13, further comprising:

forming a first insulating layer on the insulative rod and the wire before cutting off the wire； and

forming an opening in the first insulating layer and cutting off the wire.
The method of claim 14, wherein the opening includes a slot opening surrounding the insulative rod and partially exposing the insulative rod.
The method of claim 14, wherein the opening includes a dot opening partially exposing the insulative rod.
The method of claim 14, further comprising: forming a second insulating layer for covering the first insulating layer and the connection wire and filling into the opening of the first insulating layer.
The method of claim 13, further comprising: covering a first cap on a first end of the insulative rod, and covering a second cap on a second end of the insulative rod.
The method of claim 18, further comprising: electrically welding one end of the wire on the first cap, and electrically welding the other end of the wire on the second cap.
The method of claim 19, further comprising: electrically connecting an end of the first winding wire to the first cap by using a first electrical cover layer, and electrically connecting an end of the second winding wire to the second cap by using a second electrical cover layer.
The method of claim 20, wherein the first electrical cover layer, the second electrical cover layer and the connection wire are formed together by a process.