WO2009096386A1

WO2009096386A1 - Resistor and method of manufacturing resistor

Info

Publication number: WO2009096386A1
Application number: PCT/JP2009/051261
Authority: WO
Inventors: Keishi Nakamura
Original assignee: Koa Corporation
Priority date: 2008-01-30
Filing date: 2009-01-27
Publication date: 2009-08-06
Also published as: JP2009182144A

Abstract

This object aims to provide the structure of a resistor in which a resistor with a low resistant value can be precisely manufactured in a simple production process and a method of manufacturing the resistor. A resistor (10) is provided with a rod-like resistance member (11) made from a resistance alloy material and cylindrical electrodes (12a, 12b) comprised of a metallic material jointed to circumferences of both ends of the resistance member, wherein the electrodes (12a, 12b) and the resistance member (11) are jointed by a rotary swaging process. The resistor (11) has a small diameter portion (11a) and a large diameter portions (11b, 11c) that is larger in diameter than the small diameter portion and is arranged at the both edges of the small diameter portion. The electrodes (12a, 12b) are jointed with the outer circumferential surface of the large diameter portion by the rotary swaging process.

Description

Resistor and manufacturing method thereof

The present invention relates to a current detection resistor that can detect a large current with high accuracy, and has electrodes made of an electrode metal material such as copper at both ends of a resistor made of a resistance alloy material such as a copper nickel alloy. .

A resistor described in Patent Document 1 is known as an example of the current detection resistor. This resistor includes a plate-like electrode made of a highly conductive electrode metal material such as copper joined to the lower surfaces of both ends of a plate-like resistor made of a resistance alloy material such as a copper nickel alloy by rolling or the like. Further, a molten solder layer is disposed on the lower surfaces of both electrodes. According to the resistor having such a structure, it has a low resistance value of several mΩ or less, a good TCR, and no trimming cut, so that it can function as a surface mount type current detection resistor having a low series inductance. it can.

However, in the manufacture of the resistor, after joining a plate made of an electrode metal material to a plate made of a resistance alloy material by rolling or the like, it is cut into a flat shape with a rotary blade while passing through the plate. Therefore, there is a limit to the thickness accuracy of the resistance alloy material by cutting, and in order to maintain the accuracy of the resistance value variation, it was necessary to process again after making the product shape. For this reason, in order to obtain a highly accurate low resistance value, there has been a problem that the machining process becomes complicated. Further, the above-described resistor has a problem that when mounted on a printed wiring board or the like, the mounting surface is limited only to the molten solder layer on the lower surface of the electrode, and it is difficult to connect the wiring to the other surface.
JP 2002-57009 A

The present invention has been made based on the above-described circumstances, and can produce a low-resistance resistor with a simple manufacturing process with high accuracy and can be connected to a wiring pattern on a mounting board in addition to the lower surface of the resistor. It is an object of the present invention to provide a resistor having a simple electrode and a method for manufacturing the same.

The resistor of the present invention includes a rod-shaped resistor made of a resistance alloy material and a cylindrical electrode made of a metal material joined to the outer peripheral surfaces of both ends of the resistor, and the electrode and the resistor are connected to a rotary swage. It is characterized by being joined by processing. The resistor has a small-diameter portion and a large-diameter portion larger in diameter than the small-diameter portion at both ends, and an electrode is joined to the outer peripheral surface of the large-diameter portion by rotary swaging.

Also, the method of manufacturing a resistor according to the present invention comprises preparing a cylindrical resistance material made of a resistance alloy and a cylindrical electrode metal material, inserting the resistance material into the electrode metal material, and performing rotary swaging. By forming a joined body in which the resistance material and the electrode metal material are joined, and cutting the joined body while rotating, a part of the resistance material is exposed around the joined body, and the electrode metal material is removed from the joined body. A resistor and an electrode are formed separately in the axial direction.

According to the present invention, it is possible to easily obtain a joined body in which a rod-shaped resistor made of a resistance alloy material is covered with a cylindrical electrode metal material by using a rotary swaging technique for a metal tube material, A highly conductive metal electrode can be bonded with a high bonding strength to a rod-shaped resistor made of a resistance alloy material by a simple manufacturing process without requiring expensive capital investment. Then, by cutting the rod-shaped joined body while rotating it, the electrode metal material is separated in the axial direction of the joined body to form a small diameter portion of the resistor. Therefore, it is possible to easily achieve a high finished dimensional accuracy and to produce a resistor with little variation in resistance value.

FIG. 1A is a perspective view showing a resistor according to a first embodiment of the present invention. FIG. 1B is a cross-sectional view of the resistor. FIG. 2A is a perspective view showing a resistor of the modified example. FIG. 2B is a cross-sectional view of the resistor. FIG. 3A is a perspective view showing a resistor of the modified example. FIG. 3B is a cross-sectional view of the resistor. FIG. 4A is a perspective view showing a resistor of the modified example. FIG. 4B is a cross-sectional view of the resistor. FIG. 5A is a perspective view showing a resistor of the modified example. FIG. 5B is a cross-sectional view of the resistor. FIG. 6 is a cross-sectional view showing an example of mounting the resistor on a multilayer board. FIG. 7A shows the manufacturing process of the resistor according to the first embodiment in the order of steps, the left side is a perspective view and the right side is a sectional view thereof. FIG. 7B shows the manufacturing process of the resistor of the first embodiment in the order of steps, the left side is a perspective view, and the right side is a sectional view thereof. FIG. 7C shows the manufacturing process of the resistor of the first embodiment in the order of steps, the left side is a perspective view, and the right side is a sectional view thereof. FIG. 7D shows a manufacturing process of the resistor according to the first embodiment in order of steps, the left side is a perspective view, and the right side is a sectional view thereof. FIG. 8 is a perspective view showing a resistor according to the second embodiment of the present invention. FIG. 9A is a cross-sectional view showing the resistor. FIG. 9B is a plan view showing the resistor. FIG. 9C is a side view showing the resistor. FIG. 10 is a perspective view showing a modification of the resistor. FIG. 11A is a perspective view illustrating the manufacturing process of the resistor according to the second embodiment in the order of processes. FIG. 11B is a perspective view illustrating the manufacturing process of the resistor according to the second embodiment in the order of processes. FIG. 11C is a perspective view illustrating the manufacturing process of the resistor according to the second embodiment in the order of processes.

Hereinafter, an embodiment of a resistor and a manufacturing method thereof according to the present invention will be described with reference to the accompanying drawings. In addition, in each figure, the same code | symbol is attached | subjected and demonstrated to the same or equivalent member or element.

FIG. 1A is a perspective view showing a resistor according to a first embodiment of the present invention, and FIG. 1B is a sectional view thereof. The resistor 10 includes a columnar (rod-like) resistor 11 made of a resistance alloy material having a low resistivity and a good resistance temperature coefficient (TCR), such as copper nickel, nichrome, manganin, and iron chromium, and the resistor. 11 are provided with cylindrical (tubular)

electrodes

12a and 12b made of a metal material having a high conductivity such as copper or copper alloy joined to the outer peripheral surfaces of both ends. Here, the resistivity of the electrode metal material is preferably 1/50 or less of the resistivity of the resistance alloy material.

The resistor 11 has a narrow diameter portion 11a and

thick diameter portions

11b and 11c that are larger in diameter than the narrow diameter portion at both ends.

Cylindrical electrodes

12a and 11c are formed on the outer peripheral surfaces of the

large diameter portions

11b and 11c. 12b is joined. The inner peripheral surfaces of the

electrodes

12a and 12b and the outer peripheral surfaces of the resistor large-

diameter portions

11b and 11c are joined by applying pressure to the interface by a rotary sledge process (metal compression plastic deformation process) and performing a heat treatment.

For the rotary swaging, for example, a metal compression plastic deformation technique as disclosed in Japanese Patent Application Laid-Open No. 2002-158044 and Japanese Patent Application Laid-Open No. 5-74323 can be used. It is a technology to compress and plastically deform the work metal radially inward by striking (compressing) the work metal outer peripheral surface in the radial direction (toward the center of the work metal) with dies arranged around For example, it is used when caulking a core wire portion made up of a number of electric wires arranged inside a metal cylinder (see Japanese Patent Application Laid-Open No. 2002-158044).

In the resistor 10 of the present invention, a cylindrical resistor 11 and

electrodes

12a and 12b made of an electrode metal material (copper) are fixed by caulking (pressure welding) using a rotary swaging process and subsequent heat treatment. As a result, a diffusion state between the metals is formed at the interface between the inner peripheral surface of the

electrodes

12a and 12b and the outer peripheral surface of the resistor 11, and a good joint state is obtained both electrically and mechanically. A uniform and strong bonding state of the metal electrode to the resistor important for the resistor for current detection having a low resistance value can be obtained.

The small-diameter portion 11a of the resistor 11 is a portion that forms the resistance value of the resistor 10, and the resistance value of the resistor 10 is proportional to the length of the small-diameter portion 11a and inversely proportional to the cross-sectional area. For this reason, since the required resistance value accuracy can be obtained by processing the length and diameter of the small-diameter portion 11a with high accuracy, by cutting the resistor 11 while rotating the round bar-shaped resistor 11, The small-diameter portion 11a can be easily machined to a required diameter with high accuracy, whereby a low-resistance resistor can be manufactured with a simple manufacturing process and with good finishing accuracy.

The finished dimensional accuracy of flat plate cutting is usually about ± 10 to 30 μm. However, the finished dimensional accuracy of rotary cutting processing determines the diameter of the resistor material by bite machining while rotating the workpiece itself. The finishing accuracy of φ (diameter) can be ± 5μm or less. For this reason, in the rotational cutting process, the machining accuracy is higher than that in the plane cutting process, and the finish accuracy of the resistance value is improved. For example, a high resistance value accuracy within ± 1% can be easily realized. .

2A and 2B are a perspective view and a cross-sectional view showing a modification of the resistor 10 shown in FIGS. 1A and 1B. In addition to the resistor configuration shown in FIGS. 1A and 1B, the resistor 10a includes

molten solder layers

13a and 13b on the entire outer peripheral surface of

cylindrical electrodes

12a and 12b made of a metal material such as copper. The

molten solder layers

13a and 13b are formed by bringing the outer peripheral surface of the

electrodes

12a and 12b into contact with the molten solder liquid and rotating the

cylindrical electrodes

12a and 12b, thereby applying the molten solder liquid to the entire outer peripheral surface. Then, the

molten solder layers

13a and 13b solidified by cooling can be applied. Of course, a molten tin layer may be used instead of the molten solder layer.

By providing the

molten solder layers

13a and 13b on the surfaces of the

cylindrical electrodes

12a and 12b, when the resistor 10a is surface-mounted on a mounting board such as a printed board, it can be easily soldered to a wiring pad on the mounting board. Thus, the

electrodes

12a and 12b can be fixed, and the mountability of the resistor 10 can be improved.

3A and 3B are a perspective view and a cross-sectional view showing a further modification of the resistor 10 shown in FIGS. 1A and 1B. In this embodiment, the

molten solder layers

13a and 13b are provided so as to cover not only the outer peripheral surfaces of the

cylindrical electrodes

12a and 12b but also the entire end surfaces of the round bar-shaped resistor 10b. As a result, when the resistor is surface-mounted on a mounting board such as a printed circuit board, solder fillets can be formed on both end faces of the

electrodes

12a and 12b, thereby further improving the mountability of the resistor. it can. Note that the

molten solder layers

13a and 13b may be formed by plating.

Further, the resistor 10 of this embodiment includes a protective film 14 made of a resin film or the like that covers the entire outer peripheral surface of the small diameter portion 11 a of the resistor 11. Thereby, even if a foreign substance adheres to the small-diameter portion 11a of the resistor 11, any influence on the small-diameter portion 11a of the resistor 11 is prevented, and the resistor 11 can be protected.

4A and 4B are a perspective view and a cross-sectional view showing a further modification of the resistor 10 shown in FIGS. 1A and 1B. In other words, the resistor 10 shown in FIGS. 1A and 1B includes

cylindrical electrodes

12a and 12b on the outer periphery of the large-

diameter portions

11b and 11c of the columnar resistor 11. 10c is formed by pressing the electrode portion from above and below by pressing or the like to form a flat surface 12f on the surfaces of the

electrodes

12a and 12b. Thereby, when surface-mounting a round bar-shaped resistor, rolling of a round-bar-shaped resistor can be prevented and the stability of surface mounting can be improved.

FIGS. 5A and 5B are a perspective view and a cross-sectional view showing a further modification of the resistor 10 shown in FIGS. 4A and 4B. In order to form the flat surface 12f on the surfaces of the

electrodes

12a and 12b, the upper and lower portions of the

electrodes

12a and 12b are removed by cutting to form the flat surface 12f as in the resistor 10d of this modification. Good.

FIG. 6 shows an example of mounting the resistor 10 (10a-10d) on a multilayer board. In this example, the multilayer substrate is a substrate 21 provided with

wiring patterns

21a and 21b, a substrate 22 provided with openings 22a,

vias

23a and 23b, and

wiring patterns

23c and 23d including conductors passing through the vias. Etc., and the resistor 10 (10a-10d) is accommodated in the opening 22a. In the resistor 10 (10a-10d), the lower portions of the

electrodes

12a and 12b are connected to the current

supply wiring patterns

21a and 21b, and the upper portions of the

electrodes

12a and 12b are connected to the voltage

detection wiring patterns

23c and 23d. ing.

As described above, the resistor 10 (10a-10d) according to the present invention includes the

cylindrical electrodes

12a and 12b disposed on the outer circumferences of both ends of the rod-shaped resistor 11, so that the electrodes having the same potential in any direction from top to bottom and from side to side. Can be provided, and a current detecting resistor showing the same stable resistance value can be provided no matter which direction is joined to the wiring pattern of the mounting substrate. Therefore, the wiring pattern provided on the mounting board can be connected not only from the lower surface but also from the upper surface of the resistor, which is effective when used as an embedded component on a multilayer mounting board or the like.

Next, with reference to FIG. 7A thru | or FIG. 7D, the manufacturing method of the resistor of 1st Embodiment of this invention is demonstrated. First, as shown in FIG. 7A, a cylindrical resistance material 11m made of a resistance alloy material having a low resistivity and a good temperature coefficient of resistance (TCR), such as copper nickel, nichrome, manganin, and iron chromium, and the resistance material A cylindrical electrode metal material 12m made of copper or a copper alloy capable of inserting 11m inside is prepared.

Then, as shown in FIG. 7B, the resistance material 11m is inserted into the cylindrical electrode metal material 12m, and a cylindrical shape is formed on the outer peripheral surface of the columnar resistance material 11m by rotary sledge processing (metal compression plastic deformation processing). The inner peripheral surface of the electrode metal material 12m is joined by caulking to form a joined body 16 subjected to heat treatment.

Next, as shown in FIG. 7C, a part along the axial direction of the joined body 16 is cut in the radial direction while rotating the joined body 16 using a lathe or the like. That is, the electrode metal material 12m is cut from the surface in the radial direction so that a portion along the axial direction of the resistance material 11m is exposed over the periphery of the joined body, and further cut to a required diameter for resistance. A small-diameter portion 11a of the body 11 is formed. As a result, the electrode metal material 12m is separated in the axial direction of the joined body 16 across the small-diameter portion 11a of the resistor 11, and the cylindrical electrode 12 is formed. The resistor 11 has a small-diameter portion 11a and a large-diameter portion. A portion 11d is formed.

Then, by cutting along the cutting line 17 (see the right figure in FIG. 7C) at the center of the electrode 12, the electrode 12 is separated into

electrodes

12a and 12b, and as shown in FIG. 1A and FIG. 1B). Furthermore, the resistor 10a shown to FIG. 2A and FIG. 2B is obtained by providing the

molten solder layers

13a and 13b in the outer peripheral surface of

electrode

12a, 12b as needed. Further, if necessary, a protective film 14 is provided on the outer periphery of the small-diameter portion 11a of the resistor 11, and

molten solder layers

13a and 13b are provided on the outer peripheral surfaces of the

electrodes

12a and 12b and the resistor end surfaces. The resistor 10b shown in 3B is obtained.

8 is a perspective view showing a resistor according to a second embodiment of the present invention, FIG. 9A is a sectional view thereof, FIG. 9B is a plan view thereof, and FIG. 9C is a side view thereof. The resistor 30 includes a plate-like resistor 31 having flat front and back surfaces and arcs at both ends, and

electrodes

32a and 32b made of a metal material joined to both ends of the resistor 31 by rotary swaging. Prepare. The resistor 31 is made of a resistance alloy material having a low resistivity and a good resistance temperature coefficient (TCR), such as copper nickel, nichrome, manganin, and iron chromium, as in the first embodiment, and the

electrodes

32a and 32b. Is made of a high conductivity metal material such as copper or copper alloy as in the first embodiment.

The resistor 31 includes a thin plate portion 31a whose front and back surfaces are flat and

thick plate portions

31b and 31c having arcs at both ends. The outer periphery of the

thick plate portions

31b and 31c of the resistor 31 is subjected to rotary swaging.

Electrodes

32a and 32b made of bonded high conductivity metal materials are provided. By rotary swaging and heat treatment, a diffusion state of mutual metals is formed at the interface between the inner peripheral surfaces of the

electrodes

32a and 32b and the outer peripheral surfaces of the

resistors

31a and 31b, which is good both electrically and mechanically. A junction state is obtained, and a uniform and strong junction state of the electrode to the resistor important for a resistor for detecting a current having a low resistance value is obtained.

The thin plate portion 31a of the resistor 31 is a portion that forms the resistance value of the resistor 30, and the resistance value of the resistor 30 is proportional to the length of the thin plate portion 31a (interval between the

electrodes

32a and 32b). It is inversely proportional to the cross-sectional area of 31a (the cross-sectional area of the plane perpendicular to the length of the thin plate portion 31a). For this reason, a highly accurate resistance value is obtained by processing the length and cross-sectional area of the thin plate portion 31a with high accuracy.

FIG. 10 is a perspective view showing a modification of the resistor according to the second embodiment of the present invention. In this resistor 30a, the

electrodes

32a and 32b of the resistor 30 are further provided with grooves 37z in which the resistance material (the surface of the resistor 31) is exposed, further separating the electrodes, the electrode 32a into the

electrodes

32c and 32d, and the electrode 32b. Is separated into

electrodes

32e and 32f. Thereby, an electrode can be isolate | separated into a current supply terminal and a voltage detection terminal, and the resistor for current detection of a 4 terminal structure can be created.

Next, with reference to FIG. 11A thru | or FIG. 11C, the manufacturing method of the resistor of 2nd Embodiment of this invention is demonstrated. The first half of this resistor manufacturing method is the same as the first half of the resistor manufacturing method of the first embodiment shown in FIGS. 7A and 7B. That is, a cylindrical resistance material 11m made of a resistance alloy material having a low resistivity and a good resistance temperature coefficient (TCR), such as copper nickel, nichrome, manganin, and iron chromium, and the resistance material 11m can be inserted therein. A cylindrical electrode metal material 12m made of copper or a copper alloy is prepared, a resistance material 11m is inserted into the cylindrical electrode metal material 12m, and a cylindrical resistance is obtained by rotary swaging (metal compression plastic deformation processing). The inner peripheral surface of the cylindrical electrode metal material 12m is joined to the outer peripheral surface of the material 11m by caulking to form a joined body 16 subjected to heat treatment.

In the subsequent steps, unlike the resistor manufacturing method of the first embodiment, as shown in FIG. 11A, first, the joined body 16 is pressed in a vertical direction by pressing or the like to compress and plastically deform the joined body, and the outer periphery of the joined body. A flat surface 36f is formed above and below. In the compression-deformed joint 36, the cylindrical resistance material 11m is deformed into a plate-shaped resistance material 31m having flat front and back surfaces and arcuate ends, and the cylindrical electrode metal material 12m is circular at both ends. It is deformed into a cylindrical electrode metal material 32m joined to the outer periphery of an arc-shaped plate-shaped resistance material 31m.

Next, as shown in FIG. 11B, a groove 37 by cutting is formed on each of the flat surfaces 36f to expose the resistance material 31m, and a pair of elongated shapes are formed at both ends of the plate-shaped resistance material 31m. The

electrodes

32a and 32b are formed separately. At this time, the resistive material 31m is formed with a thin plate portion 31a having flat front and back surfaces and

thick plate portions

31b and 31c having arcs at both ends (see FIG. 11C). Since it is a part that forms a resistance value, it is cut so as to obtain a thickness corresponding to the required resistance value.

Next, as shown in FIG. 11C, the joined body 36 is cut to a required length to be separated into individual resistors 30. Thus, the resistor 30 according to the second embodiment of the present invention shown in FIG. 8 is obtained. It is done. Each of the

electrodes

32a and 32b of this resistor is further provided with a groove in which the resistance material 31m is exposed, so that each of the

electrodes

32a and 32b is further separated, and the four-terminal structure current detecting resistor shown in FIG. It can also be. Moreover, you may make it provide a molten solder layer or a solder plating electrode in the protective film surrounding the thin-plate part 31a of the resistor 31, and an electrode part similarly to the resistor of 1st Embodiment shown to FIG.

Further, if necessary, the thickness of the thin plate portion 31a of the resistor 31 may be adjusted to trim the resistance value. In addition, although the example which cuts and separates to each resistor 30 after forming the groove | channel 37 in the elongate joined body 36 was demonstrated, the elongate joined body 36 is cut | disconnected and separated to each resistor 30 After that, the groove 37 may be formed to separate the

electrodes

32a and 32b.

According to the method of manufacturing a resistor of the second embodiment of the present invention, a rod-shaped resistance alloy material is inserted into a cylindrical electrode metal material, and a joined body is formed by pressure welding (swaging) and heat treatment. Crushing is performed to form flat surfaces above and below the outer periphery of the joined body, and grooves are formed by cutting on each of the flat surfaces to expose the resistance material and to form a pair of electrodes. A metal plate resistor having an arc-shaped electrode on the end face can be easily obtained by cutting to a size of.

Therefore, since there is no need for expensive equipment investment such as electron beam welding, and heat treatment can be easily performed as a wire rod, it is possible to dramatically improve the bondability of the electrode metal material to the resistance alloy material as compared with the caulking method. . And since the metal electrodes with flat shapes on the upper and lower surfaces can be formed on the left and right sides of the plate-shaped resistor at the arc-shaped end surface, it is a surface-mount type metal plate resistor, and easy to form fillets when soldering The stress can be relieved by the arc-shaped metal electrode against the stress accompanying the expansion and contraction of the mounting substrate due to thermal stress such as heat cycle, and a metal plate resistor resistant to stress can be realized.

Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

The resistor of the present invention is a current detection resistor capable of detecting a large current with high accuracy, having electrodes made of an electrode metal material such as copper at both ends of a resistor made of a resistance alloy material such as a copper nickel alloy. It can be used in a vessel.

Claims

A rod-shaped resistor made of a resistance alloy material;
A cylindrical electrode made of a metal material joined to the outer peripheral surfaces of both ends of the resistor,
A resistor comprising the electrode and the resistor joined by rotary swaging.
The resistor has a narrow-diameter portion and a thick-diameter portion having a diameter larger than that of the thin-diameter portion at both ends thereof, and the electrode is joined to an outer peripheral surface of the large-diameter portion. Item 1. The resistor according to item 1.
2. The resistor according to claim 1, wherein the resistor is cylindrical and the electrode is cylindrical.
The resistor according to claim 1, wherein a flat surface is formed on the surface of the electrode.
Prepare a cylindrical resistance material made of a resistance alloy and a cylindrical electrode metal material,
Inserting the resistive material into the electrode metal material;
Forming a joined body obtained by joining the resistance material and the electrode metal material by rotary swaging;
By cutting while cutting the joined body, a part of the resistance material is exposed around the joined body, and the electrode metal material is separated in the axial direction of the joined body, so that the resistor and the electrode are separated. Forming a resistor.
6. The method of manufacturing a resistor according to claim 5, wherein a flat surface is formed on the electrode.
A plate-like resistor whose front and back surfaces are flat and arc-shaped at both ends;
A resistor comprising an electrode made of an electrode metal material joined to both ends of the resistor by rotary swaging.
The resistor according to claim 7, wherein the electrode is further separated at both ends of the resistor.
Prepare a cylindrical resistance material made of a resistance alloy and a cylindrical electrode metal material,
Inserting the resistive material into the electrode metal material;
Forming a joined body obtained by joining the resistance material and the electrode metal material by rotary swaging;
Pressing the joined body to form flat surfaces above and below the outer periphery of the joined body,
A method for manufacturing a resistor, comprising: forming a groove by cutting on each of the flat surfaces to expose the resistance material and forming a pair of electrodes.
10. The method of manufacturing a resistor according to claim 9, wherein the electrode is further provided with a groove in which the resistance material is exposed, and the electrode is further separated.