Transformer bushing and method for preparing the same

Abstract

The present application discloses a transformer bushing and a method for preparing the transformer bushing, wherein the transformer bushing comprises: a conductive rod; multiple insulating layers and multiple capacitor screens, which are alternately arranged on the periphery of the conductive rod, wherein the capacitor screen farthest from the conductive rod is defined as the end screen, and the capacitor screen closest to the end screen is defined as the second end screen; the second end screen comprises a first end portion protruding axially from the end screen; a conductive connector, which extends from the first end portion of the second end screen to the side of the end screen away from the conductive rod, and a first insulating layer is provided between the conductive connector and the end screen, and a second insulating layer is provided on the side of the conductive connector away from the end screen; a voltage tap lead, one end of which passes through the second insulating layer and is electrically connected to the conductive connector, and the other end of which extends to the outside of the transformer bushing. In the above manner, the present application can prevent the voltage tap lead from passing through the end screen when it is led out.

Description

Technical Field

[0001] The present application relates to the technical field of transformers, and in particular to a transformer bushing and a method for preparing the transformer bushing. Background Art

[0002] In the US standard, the measurement taps of transformer bushings generally include: voltage taps and test taps. The voltage tap leads must be drawn from the secondary end screen of the transformer bushing, and the test tap leads must be drawn from the end screen of the transformer bushing. The voltage tap can provide power to external test instruments when measuring through the test tap, and of course it can also be used directly for measurement; the test tap can be used to measure, for example, dielectric loss, capacitance, etc.

[0003] The inventors of the present application have discovered during long-term research that the voltage tap lead of the existing transformer bushing needs to pass through the end screen, which may result in insufficient withstand voltage between the end screen and the sub-end screen, thereby causing the transformer bushing to fail partial discharge or even breakdown. Summary of the invention

[0004] The purpose of the present application is to provide a transformer bushing and a method for preparing the transformer bushing, which can prevent the voltage tap lead from passing through the end screen when leading out.

[0005] To achieve the above-mentioned purpose, a technical solution adopted in the present application is: to provide a transformer bushing, the transformer bushing comprising: a conductive rod; multiple insulating layers and multiple capacitor screens, which are alternately arranged on the periphery of the conductive rod, wherein the capacitor screen farthest from the conductive rod is defined as an end screen, and the capacitor screen closest to the end screen is defined as a second end screen; the second end screen comprises a first end portion protruding axially from the end screen; a conductive connector extending from the first end portion of the second end screen to a side of the end screen away from the conductive rod, and a first insulating layer is provided between the conductive connector and the end screen, and a second insulating layer is provided on a side of the conductive connector away from the end screen; a voltage tap lead, one end of which passes through the second insulating layer and is electrically connected to the conductive connector, and the other end of which extends to the outside of the transformer bushing.

[0006] Wherein, the conductive connecting member includes: a first lead, one end of which is electrically connected to the first end portion, and the other end of which extends to the surface of the first insulating layer; a first metal sheet, located on the surface of the first insulating layer, one end of the first metal sheet is electrically connected to the other end of the first lead, and the other end of the first metal sheet is electrically connected to the voltage tap lead.

[0007] Wherein, the first metal sheet is copper foil, and the width of the copper foil is 20 mm-50 mm.

[0008] Wherein, the conductive connecting member further comprises: a second metal sheet located on a side surface of the first end portion of the secondary end screen away from the conductive rod, and the second metal sheet is electrically connected to the one end of the first lead.

[0009] Wherein, the conductive connecting member includes: a conductive block, which is located on the surface of the first end of the secondary end screen away from the side of the conductive rod, and the conductive block is flush with the first insulating layer; a third metal sheet, which is located on the surface of the first insulating layer, one end of which is electrically connected to the surface of the conductive block exposed from the first insulating layer, and the other end of which is electrically connected to the voltage tap lead.

[0010] Wherein, the end screen includes a second end portion axially protruding from the conductive connecting piece; the transformer bushing also includes: a test tap lead, one end of which passes through the first insulating layer and the second insulating layer outside the second end portion and is electrically connected to the second end portion, and the other end of which extends to the outside of the transformer bushing.

[0011] Wherein, the transformer bushing further includes: a flange, which is sleeved on the periphery of the second insulating layer, and the voltage tap lead and the test tap lead are both led out through the flange.

[0012] The voltage tap lead is led out from a first position of the second insulating layer, and the test tap lead is led out from a second position of the second insulating layer; in the radial direction of the transformer bushing, the first position and the center point of the transformer bushing have a first connecting line, the second position and the center point have a second connecting line, and the angle between the first connecting line and the second connecting line is between 30° and 180°; and / or the angle between the connecting line between the first position and the second position and the axial direction of the transformer bushing is between 70° and 90°.

[0013] To achieve the above-mentioned purpose, another technical solution adopted in the present application is: to provide a method for preparing a transformer bushing, the preparation method comprising: alternately winding multiple layers of insulating layers and multiple layers of capacitor screens around the outer periphery of a conductive rod; wherein the capacitor screen farthest from the conductive rod is defined as an end screen, and the capacitor screen closest to the end screen is defined as a second end screen; the second end screen includes a first end portion protruding axially from the end screen; after forming the end screen and a first insulating layer outside the end screen, a first opening is opened on the first insulating layer, and the first opening extends to the first end portion of the second end screen; one end of a conductive connector is electrically connected to the first end portion through the first opening, and the other end of the conductive connector is extended to the first insulating layer; a second insulating layer is formed outside the conductive connector, and a second opening is formed on the second insulating layer, and the second opening extends to the other end of the conductive connector; a voltage tap lead is electrically connected to the conductive connector through the second opening.

[0014] Among them, the step of passing one end of the conductive connector through the first opening and electrically connecting it to the first end, and extending the other end of the conductive connector to the first insulating layer includes: passing one end of a first lead through the first opening and electrically connecting it to the first end, and extending the other end of the first lead to the surface of the first insulating layer; and setting a first metal sheet on the surface of the first insulating layer, and electrically connecting one end of the first metal sheet to the other end of the first lead.

[0015] Different from the prior art, the transformer bushing provided by the present application includes a conductive connector, one end of which is connected to the secondary end screen, the other end of which extends to the side of the end screen away from the conductive rod, and a first insulating layer is provided between the conductive connector and the end screen, and a second insulating layer is provided on the side of the conductive connector away from the end screen; one end of the voltage tap lead is electrically connected to the conductive connector after passing through the second insulating layer. The beneficial effect of the present application is that the voltage tap lead is led out from the secondary end screen through the conductive connector, and the conductive connector extends from the first end of the secondary end screen that is not covered by the end screen to the side of the end screen away from the secondary end screen, and the conductive connector does not pass through the end screen, that is, when the present application leads the voltage tap lead out from the secondary end screen through the conductive connector, neither the conductive connector nor the voltage tap lead needs to pass through the end screen, and the insulation strength is high, which reduces the probability of partial discharge failure or even breakdown of the transformer bushing due to the setting method of the voltage tap lead.

[0016] In addition, in the present application, the conductive connector includes a first metal sheet, which is located on the surface of the first insulating layer. The first metal sheet is copper foil, which has good conductivity and a soft texture, and is convenient for subsequent winding. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0018] Figure 1 A cross-sectional schematic diagram of an implementation method of a transformer bushing of the present application;

[0019] Figure 2 for Figure 1 An enlarged schematic diagram of an implementation method of the boxed area;

[0020] Figure 3 for Figure 1 An enlarged schematic diagram of another implementation method of the boxed area;

[0021] Figure 4 This is a structural schematic diagram of another embodiment of the transformer bushing of the present application;

[0022] Figure 5 for Figure 2 A cross-sectional schematic diagram of an embodiment of a transformer bushing;

[0023] Figure 6 This is a schematic flow chart of an implementation method of a transformer bushing preparation method according to the present application. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] See also Figure 1-Figure 2 , Figure 1 This is a cross-sectional schematic diagram of an embodiment of a transformer bushing of the present application. Figure 2 for Figure 1 The enlarged schematic diagram of an embodiment of the box area in the figure, the transformer bushing 10 comprises:

[0026] Conductive rod 100; in the present embodiment, the conductive rod 100 may be made of a metal material such as aluminum or copper, and the conductive rod 100 may be configured as a conductive tube with a hollow structure or a solid structure.

[0027] Multiple layers of insulating layers (not marked) and multiple layers of capacitor screens (not marked) are alternately arranged on the periphery of the conductive rod 100, that is, a layer of capacitor screen is arranged between two adjacent layers of insulating layers, and a layer of insulating layer is arranged between two adjacent layers of capacitor screens; the material of the capacitor screen can be aluminum foil, electroplated cloth, carbon fiber cloth, etc. Among them, the capacitor screen farthest from the conductive rod 100 is defined as the end screen 102, and the capacitor screen closest to the end screen 102 is defined as the second end screen 104, and the second end screen 104 includes a first end 1040 axially protruding from the end screen 102, that is, the positive projection of the end screen 102 on the second end screen 104 does not cover the second end screen 104, and the first end 1040 of the second end screen 104 is exposed from the projection of the end screen 104. Specifically, the multiple layers of insulating layers and the multiple layers of capacitor screens can be directly wound around the conductive rod 100 in sequence; or a winding tube can be arranged outside the conductive rod 100, and the multiple layers of insulating layers and the multiple layers of capacitor screens are wound on the winding tube in sequence.

[0028] The conductive connector 106 extends from the first end 1040 of the secondary end screen 104 to the end screen 102 away from the conductive rod 100 , and a first insulating layer 108 is provided between the conductive connector 106 and the end screen 102 . A second insulating layer 101 is provided on the side of the conductive connector 106 away from the end screen 102 .

[0029] The voltage tap lead 103 has one end passing through the second insulating layer 101 to be electrically connected to the conductive connector 106 , and the other end extending to the outside of the transformer bushing 10 .

[0030] In this embodiment, when the voltage tap lead 103 is led out from the secondary end screen 104 through the conductive connector 106, neither the conductive connector 106 nor the voltage tap lead 103 needs to pass through the end screen 102, and the insulation strength is high, which reduces the probability of partial discharge failure or even breakdown of the transformer bushing 10 due to the setting method of the voltage tap lead 103.

[0031] In one embodiment, please refer to Figure 2, the conductive connector 106 includes a first lead 160 and a first metal sheet 162; one end of the first lead 160 is electrically connected to the first end 1040, and the other end of the first lead 160 extends to the surface of the first insulating layer 108. For example, the first lead 160 can extend 30 mm along the axial direction on the surface of the first insulating layer 108. One end of the first lead 160 can be electrically connected to the first end 1040 by welding or the like, and the first lead 160 can be a copper wire or the like; in addition, in other embodiments, the first lead 160 can also extend in other directions, and the electrical connection method can also be crimping or the like, or other metal wires such as aluminum wires or the like, which are not limited here. The first metal sheet 162 is located on the surface of the first insulating layer 108, and one end of the first metal sheet 162 is electrically connected to the other end of the first lead 160. For example, the electrical connection can be achieved by welding or the like, and the other end of the first metal sheet 162 is electrically connected to the voltage tap lead 103. The first metal sheet 162 extends along the axial direction on the surface of the first insulating layer 108, and the extended length can be calculated according to the product, for example, the length can be 188mm, etc. The specific extended length is designed according to the specifications of different products. In addition, in the present embodiment, the first metal sheet 162 can be a copper foil, and the width of the copper foil is 20mm-50mm, for example, 20mm, 30mm, 40mm, 50mm, etc. In the present embodiment, the copper foil has good conductivity and a soft texture, which is convenient for later winding. Of course, in other embodiments, the conductive connector 106 may also include only the first lead 160, which is electrically connected to the voltage tap lead 103 after extending to a predetermined position along the axial direction on the surface of the first insulating layer 108.

[0032] In another embodiment, please continue to refer to Figure 2 In addition to the first lead 160 and the first metal sheet 162, the conductive connector 106 also includes a second metal sheet 164, which is located on the side surface of the first end 1040 of the secondary end screen 104 away from the conductive rod 100. The second metal sheet 164 is electrically connected to one end of the first lead 160, for example, by welding or the like. In this embodiment, the second metal sheet 164 can be a hard copper foil or the like. Since the material of the secondary end screen 104 is generally aluminum foil, which is relatively soft, the second metal sheet 164 is introduced as a welding point to ensure the welding strength of the first lead 160.

[0033] In yet another embodiment, see Figure 3 , Figure 3 for Figure 1An enlarged schematic diagram of another embodiment of the box area. In this embodiment, the conductive connector 106a includes a conductive block 160a and a third metal sheet 162a; wherein the conductive block 160a is located on the surface of the first end 1040a of the secondary end screen 104a away from the conductive rod 100a, and the conductive block 160a is flush with the first insulating layer 108a; the conductive block 160a can be a copper block, solder, etc. The third metal sheet 162a is located on the surface of the first insulating layer 108a, one end of which is electrically connected to the surface of the conductive block 160a exposed from the first insulating layer 108a, and the other end of which is electrically connected to the voltage tap lead 103a. The third metal sheet 162a can be a copper foil, and the width of the copper foil is 20mm-50mm, for example, 20mm, 30mm, 40mm, 50mm, etc. In this embodiment, the copper foil has good conductivity and soft texture, which is convenient for later winding. Of course, in other embodiments, the third metal sheet 162a can also be replaced by a lead, for example, a copper wire, etc.

[0034] In yet another embodiment, please refer again to Figure 2 , the end screen 102 includes a second end 1020 that protrudes axially from the conductive connector 106; that is, the orthographic projection of the conductive connector 106 on the end screen 102 does not completely cover the end screen 102, and the second end 1020 of the end screen 102 is exposed from the orthographic projection of the conductive connector 106. The transformer bushing 10 provided in the present application also includes a test tap lead 105, one end of which passes through the first insulating layer 108 and the second insulating layer 101 outside the second end 1020 and is electrically connected to the second end 1020, and the other end of which extends to the outside of the transformer bushing 10. During testing, the voltage tap lead 103 can provide power to the external test instrument, and the test tap lead 105 can perform measurements, for example, measuring dielectric loss, measuring capacitance, etc. In an application scenario, please refer to Figure 1 , Figure 2 and Figure 4 , Figure 4 FIG. 1 is a schematic diagram of another embodiment of the transformer bushing of the present application. In this embodiment, the transformer bushing 10 further includes a flange 200 ( Figure 1 The flange 200 is not shown in the figure, and is sleeved on the outer periphery of the second insulating layer 101, and the voltage tap lead 103 and the test tap lead 105 are both led out through the flange 200. Specifically, an insulating tube is further provided outside the second insulating layer 101, and the flange 200 is glued outside the insulating tube, and the voltage tap lead 103 and the test tap lead 105 both pass through the insulating tube and are led out through the flange 200.

[0035] In this embodiment, if Figure 2As shown, the voltage tap lead 103 is led out from the first position A of the second insulating layer 101, and the test tap lead 105 is led out from the second position B of the second insulating layer 101; the angle between the connecting line L1 of the first position A and the second position B and the axial direction L2 of the transformer bushing 10 is between 70° and 90°, for example, 70°, 80°, 90°, etc. The voltage tap lead 103 and the test tap lead 105 are generally fixed on the flange 200 through terminals, and the terminals are generally large, and the voltage tap terminals are larger than the test tap terminals. The flange 200 will be subjected to bending moments during testing and operation. During installation, the test tap terminals should be kept away from the upper gluing position as much as possible so that the flange 200 has sufficient thickness at this position to increase strength, thereby generating an angle between L1 and L2. When the above design method is adopted, the height of the flange 200 can be reduced.

[0036] In addition, in this embodiment, Figure 5 As shown, Figure 5 for Figure 2 A cross-sectional schematic diagram of an embodiment of a transformer bushing in FIG. In the radial direction of the transformer bushing 10, the first position A and the center point C of the transformer bushing 10 have a first connection line L3, the second position B and the center point C have a second connection line L4, and the angle between the first connection line L3 and the second connection line L4 is between 30° and 180°, for example, 30°, 45°, 90°, 120°, 145°, 180°, etc. This design method can stagger the terminals of the voltage tap lead 103 and the test tap lead 105 to have a sufficient installation distance.

[0037] Please also read Figure 2 and Figure 6 , Figure 6 This is a flow chart of an embodiment of a method for preparing a transformer bushing of the present application, the preparation method comprising:

[0038] S101: Multiple insulating layers and multiple capacitor screens are alternately wound around the outer periphery of the conductive rod 100; wherein the capacitor screen farthest from the conductive rod 100 is defined as the end screen 102, and the capacitor screen closest to the end screen 102 is defined as the second end screen 104; the second end screen 104 includes a first end portion 1040 protruding axially from the end screen 102.

[0039] Specifically, the above step S101 specifically includes: firstly, wrapping an insulating layer around the outer periphery of the conductive rod 100, so that the insulating layer is directly attached to the conductive rod 100; after the insulating layer is wrapped, the capacitive screen is wrapped; after the capacitive screen is wrapped, the insulating layer is wrapped again, and the above steps are repeated to wrap multiple layers of insulating layers and multiple layers of capacitive screen around the outer periphery of the conductive rod 100. In addition, in the present embodiment, in the direction away from the conductive rod 100, the length of the capacitive screen gradually decreases, and the multiple layers of capacitive screen are arranged in a stepped shape.

[0040] S102 : After the last screen 102 and the first insulating layer 108 outside the last screen 102 are formed, a first opening (not shown) is opened on the first insulating layer 108 , and the first opening extends to the first end 1040 of the second-last screen 104 .

[0041] Specifically, in this embodiment, a first opening may be opened on the first insulating layer 108 by using a cutter, laser or the like. The first opening may extend in a straight line or in a curve.

[0042] S103 : passing one end of the conductive connecting member 106 through the first opening to electrically connect to the first end portion 1040 , and extending the other end of the conductive connecting member 106 onto the first insulating layer 108 .

[0043] Specifically, in the above step S103 , one end of the conductive connecting member 106 may be electrically connected to the first end portion 1040 by welding or the like.

[0044] S104 : forming a second insulating layer 101 outside the conductive connecting member 106 , and forming a second opening on the second insulating layer 101 , wherein the second opening extends to the other end of the conductive connecting member 106 .

[0045] Specifically, the second insulating layer 101 may be formed on the outer side of the conductive connection member 106 by winding; and the second opening may be formed on the second insulating layer 101 by cutting or laser.

[0046] S105 : Pass the voltage tap lead 103 through the second opening to electrically connect to the conductive connection member 106 .

[0047] Specifically, the voltage tap lead 103 and the other end of the conductive connector 106 may be electrically connected by welding or the like.

[0048] In one embodiment, when the structure of the conductive connecting member 106 is Figure 2 , the above step S103 specifically includes: A. passing one end of the first lead 160 through the first opening and electrically connecting it to the first end 1040, and extending the other end of the first lead 160 to the surface of the first insulating layer 108; for example, the first lead 160 can be fixedly connected to the first end 1040 by solder, and the gap between the first opening and the first lead 160 can be filled with solder. B. setting the first metal sheet 162 on the surface of the first insulating layer 108, and one end of the first metal sheet 162 is electrically connected to the other end of the first lead 160.

[0049] Of course, in this embodiment, in order to increase the welding strength between the first lead 160 and the first end 1040, before the above-mentioned step S102, it also includes: after the secondary end screen 104 is formed, a second metal sheet 164 is set at the first end 1040 of the secondary end screen 104; the above-mentioned step S102 specifically includes: after the end screen 102 and the first insulating layer 108 outside the end screen 102 are formed, a first opening (not shown) is opened on the first insulating layer 108, and the first opening extends to the second metal sheet 164 set on the first end 1040 of the secondary end screen 104.

[0050] In another embodiment, when the structure of the conductive connecting member 106a is as follows Figure 3 As shown in , the above step S103 specifically includes: A. Disposing a conductive block 160a (e.g., a copper block, solder, etc.) in the first opening, and the conductive block 160a can be flush with the height of the first insulating layer 108a. B. Disposing a third metal sheet 162a on the surface of the first insulating layer 108a, and one end of the third metal sheet 162a is electrically connected to the surface of the conductive block 160a exposed from the first insulating layer 108a.

[0051] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A transformer bushing, characterized in that: The transformer bushing comprises: Conductive rod; Multiple insulating layers and multiple capacitive screens are alternately arranged around the conductive rod, wherein the capacitive screen farthest from the conductive rod is defined as an end screen, and the capacitive screen closest to the end screen is defined as a second end screen; the second end screen includes a first end portion axially protruding from the end screen; A conductive connecting member extending from the first end of the secondary end screen to a side of the end screen away from the conductive rod, with a first insulating layer between the conductive connecting member and the end screen, and a second insulating layer disposed on a side of the conductive connecting member away from the end screen; a voltage tap lead, one end of which passes through the second insulating layer and is electrically connected to the conductive connector, and the other end of which extends to the outside of the transformer bushing; Wherein, the end screen includes a second end portion axially protruding from the conductive connector; the transformer bushing also includes: a test tap lead, one end of which passes through the first insulating layer and the second insulating layer outside the second end portion and is electrically connected to the second end portion, and the other end of which extends to the outside of the transformer bushing; The transformer bushing further comprises: a flange, which is sleeved on the periphery of the second insulating layer, and the voltage tap lead and the test tap lead are both led out through the flange; At the same time, the conductive connecting member includes: a first lead, one end of which is electrically connected to the first end portion, and the other end of which extends to the surface of the first insulating layer; a first metal sheet, located on the surface of the first insulating layer, one end of the first metal sheet is electrically connected to the other end of the first lead, and the other end of the first metal sheet is electrically connected to the voltage tap lead; Alternatively, the conductive connector includes: a conductive block, located on the surface of the first end of the secondary screen away from the side of the conductive rod, and the conductive block is flush with the first insulating layer; a third metal sheet, located on the surface of the first insulating layer, one end of which is electrically connected to the surface of the conductive block exposed from the first insulating layer, and the other end of which is electrically connected to the voltage tap lead.

2. The transformer bushing according to claim 1, characterized in that: When the conductive connection member includes the first lead and the first metal sheet, the first metal sheet is a copper foil, and the width of the copper foil is 20 mm-50 mm.

3. The transformer bushing according to claim 2, characterized in that: The conductive connector also includes: The second metal sheet is located on a side surface of the first end portion of the secondary end screen away from the conductive rod, and the second metal sheet is electrically connected to the one end of the first lead.

4. The transformer bushing according to claim 1, characterized in that: The voltage tap lead is led out from a first position of the second insulating layer, and the test tap lead is led out from a second position of the second insulating layer; In the radial direction of the transformer bushing, the first position and the center point of the transformer bushing have a first connecting line, the second position and the center point have a second connecting line, and the angle between the first connecting line and the second connecting line is between 30° and 180°; and / or, The angle between the line connecting the first position and the second position and the axial direction of the transformer bushing is between 70° and 90°.

5. A method for preparing a transformer bushing according to any one of claims 1 to 4, characterized in that: The preparation method comprises: Multiple layers of insulating layers and multiple layers of capacitive screens are alternately wound around the outer periphery of the conductive rod; wherein the capacitive screen farthest from the conductive rod is defined as an end screen, and the capacitive screen closest to the end screen is defined as a second end screen; the second end screen includes a first end portion axially protruding from the end screen; After the end screen and the first insulating layer outside the end screen are formed, a first opening is opened on the first insulating layer, and the first opening extends to the first end of the secondary end screen; Passing one end of the conductive connector through the first opening to electrically connect to the first end portion, and extending the other end of the conductive connector to the first insulating layer; forming a second insulating layer outside the conductive connecting member, and forming a second opening on the second insulating layer, wherein the second opening extends to the other end of the conductive connecting member; A voltage tap lead is passed through the second opening to electrically connect to the conductive connection member.

6. The preparation method according to claim 5, characterized in that: The step of passing one end of the conductive connector through the first opening and electrically connecting the first end portion, and extending the other end of the conductive connector onto the first insulating layer, comprises: Passing one end of a first lead through the first opening and electrically connecting it to the first end portion, and extending the other end of the first lead to the surface of the first insulating layer; A first metal sheet is disposed on the surface of the first insulating layer, and one end of the first metal sheet is electrically connected to the other end of the first lead.

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