Shunt resistors and shunt resistor devices

Abstract

To provide a shunt resistor enabling suppression of variations of a characteristic thereof depending on a connection position of wiring for detecting voltage.SOLUTION: A shunt resistor 1 comprises an electrode member 10. The electrode member 10 comprises: a contact portion 10a coming in contact with a resistor 5; and a slit 20 formed in a contact portion 10a.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a shunt resistor and a shunt resistor device. [Background technology]

[0002] There are shunt resistors that pass a current through a resistor and detect the magnitude of the current from the voltage across the resistor (see, for example, Patent Document 1). Such shunt resistors include a disk-shaped resistor and two electrodes formed on both sides of the resistor. One of the two electrodes is connected to a wiring (pad), and the other is connected to a bonding wire. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-170478 A Summary of the Invention [Problem to be solved by the invention]

[0004] The electrodes connected to the bonding wire have a potential distribution. Therefore, if the connection position of the bonding wire is shifted, the detected resistance value and the temperature coefficient of resistance (TCR) of the shunt resistor may change. The temperature coefficient of resistance is an index that indicates the rate of change in resistance value due to temperature.

[0005] Therefore, an object of the present invention is to provide a shunt resistor and a shunt resistor device that can suppress variations in the characteristics of the shunt resistor due to the connection position of the wiring for voltage detection. [Means for solving the problem]

[0006] In one aspect, a shunt resistor is provided, comprising an electrode member made of a conductive material, the electrode member comprising a contact portion that contacts a resistor and a slit formed in the contact portion.

[0007] In one embodiment, the slits extend in a direction perpendicular to the direction of the current. In one embodiment, the contact portion has a first surface adjacent to the resistor and a second surface opposite the first surface, and the slit is a through hole connected to the first surface and the second surface.

[0008] In one embodiment, a shunt resistor device is provided that includes a resistor, an electrode member having a contact portion that contacts the resistor, and a voltage detection wiring connected to the electrode member. The electrode member has a slit formed in the contact portion, and the voltage detection wiring is disposed in a first wiring region between the slit and a slit side end of the electrode member.

[0009] In one embodiment, the shunt resistor device includes a current wiring connected to the electrode member, the current wiring being arranged in a second wiring region opposite the first wiring region across the slit. In one embodiment, the slits extend in a direction perpendicular to the direction of the current. In one embodiment, the contact portion has a first surface adjacent to the resistor and a second surface opposite the first surface, and the slit is a through hole connected to the first surface and the second surface. Effect of the Invention

[0010] According to the present invention, by forming a slit at the contact portion, it is possible to suppress variation in the characteristics of the shunt resistor due to the connection position of the wiring for voltage detection. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view illustrating an embodiment of a shunt resistor for current sensing. [Diagram 2] FIG. 1 is a perspective view illustrating an embodiment of a shunt resistor for current sensing. [Diagram 3] FIG. 2 illustrates one embodiment of a mounting land pattern. [Figure 4] 4 is a diagram showing a shunt resistor device mounted on the mounting land pattern shown in FIG. 3. [Diagram 5] FIG. 13 is a diagram for explaining measurement positions of resistance value and TCR to verify the effectiveness of the shunt resistor having slits formed therein in this embodiment. [Figure 6] 1 is a graph showing changes in resistance value of a shunt resistor depending on the measurement position. [Figure 7] 1 is a graph showing changes in TCR of a shunt resistor depending on the measurement position. [Figure 8] FIG. 13 illustrates another embodiment of a shunt resistor. [Figure 9] FIG. 13 illustrates another embodiment of a shunt resistor. [Figure 10] 10 is a diagram showing an embodiment of a shunt resistor device configured by mounting the shunt resistor shown in FIG. 9 on the mounting land pattern shown in FIG. [Figure 11] 10 is a diagram showing another embodiment of a shunt resistor device configured by mounting the shunt resistor shown in FIG. 9 on the mounting land pattern shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are designated by the same reference numerals and redundant description will be omitted.

[0013] Figures 1 and 2 are perspective views showing one embodiment of a shunt resistor for current detection. As shown in Figures 1 and 2, the shunt resistor 1 includes a plate-shaped (thin plate) resistive element 5 having a predetermined thickness and width, a plate-shaped (thin plate) electrode 6 made of a conductive material, and an electrode member 10 made of a conductive material.

[0014] An example of the material of the resistor 5 is a low resistance alloy material such as a Cu-Mn-Ni based alloy or a Ni-Cr based alloy. An example of the material of the electrodes 6 and the electrode members 10 is copper (Cu), which is a highly conductive metal.

[0015] The resistor 5 has a first resistor surface 5a and a second resistor surface 5b which is the surface opposite to the first resistor surface 5a. The electrode member 10 is connected to the first resistor surface 5a, and the electrode 6 is connected to the second resistor surface 5b. That is, the electrode 6, the resistor 5, and the electrode member 10 are layered in this order in the thickness direction of the shunt resistor 1.

[0016] 1 and 2, the thickness direction of the shunt resistor 1 is a direction parallel to the vertical direction. The first direction is the length direction of the shunt resistor 1. The second direction is the width direction of the shunt resistor 1, which is a direction perpendicular to the first direction.

[0017] The electrode member 10 includes a main body 11 having a rectangular shape, and a terminal portion 14 extending in the thickness direction from the main body 11. The main body 11 and the terminal portion 14 are an integrally molded member.

[0018] The electrode member 10 (more specifically, the main body portion 11) has a contact portion 10a that contacts the resistor 5. By moving the electrode member 10 in the direction indicated by the outlined arrow in FIG. 1, the contact portion 10a of the electrode member 10 is connected to the resistor 5 (see FIG. 2). The terminal portion 14 is disposed on the opposite side of the contact portion 10a with respect to a center line CL of the electrode member 10. The center line CL is an imaginary line segment that extends parallel to the second direction of the shunt resistor 1 and bisects the electrode member 10.

[0019] The terminal portion 14 and the electrode 6 (and the resistor 5) are disposed spaced apart from each other in a first direction of the shunt resistor 1. This first direction is parallel to the direction of current flow through the shunt resistor 1.

[0020] The electrode member 10 may be connected to the first resistor surface 5a of the resistor 5 by a connection means such as welding such as pressure welding, solder, metal nanoparticles (silver paste using silver nanoparticles, copper paste using copper nanoparticles), etc. The electrode 6 may also be connected to the second resistor surface 5b of the resistor 5 by a similar connection means. The terminal portion 14 and the electrode 6 are subjected to a surface treatment such as Sn plating or Ni plating to enable solder mounting.

[0021] 1 and 2, the electrode member 10 has a slit 20 formed in the contact portion 10a. The slit 20 is a long hole extending in a direction perpendicular to the current direction (i.e., a direction parallel to the second direction).

[0022] The slit 20 penetrates from the surface of the electrode member 10 to reach the resistor 5. More specifically, the contact portion 10a has a first surface 21 adjacent to the resistor 5 and a second surface 22 opposite to the first surface 21, and the slit 20 is a through hole connected to the first surface 21 and the second surface 22.

[0023] The electrode member 10 has both ends 23, 24 in the first direction. The end 23 is a slit-side end adjacent to the slit 20, and the end 24 is an opposite end spaced apart from the slit 20. Thus, the distance between the slit 20 and the slit-side end 23 is smaller than the distance between the slit 20 and the opposite end 24.

[0024] 2, a voltage detection wiring 25 is connected during mounting to a wiring area A1 (a frame surrounded by a dotted line) between the slit 20 and the slit-side end 23. This voltage detection wiring 25 is a wiring (terminal) for detecting a potential difference in the resistor 5 (a potential difference generated between the first resistor surface 5a and the second resistor surface 5b). The resistor 5, the electrode member 10, and the voltage detection wiring 25 connected to the electrode member 10 constitute a shunt resistor device 100.

[0025] In one embodiment, the voltage detection wiring 25 may be a bonding wire. In this case, the wiring area A1 of the electrode member 10 (more specifically, the contact portion 10a) is subjected to a surface treatment (e.g., NiP plating, Ni plating, etc.) that enables bonding.

[0026] Fig. 3 is a diagram showing one embodiment of a mounting land pattern. Fig. 4 is a diagram showing a shunt resistor device 100 mounted on the mounting land pattern shown in Fig. 3. As shown in Figs. 3 and 4, a lead wire 33 is disposed between the current-carrying patterns 30 and 31, and the lead wire 33 is connected to the current-carrying pattern 31. The lead wire 33 is a voltage detection terminal for detecting the voltage of the resistor 5.

[0027] The current-carrying patterns 30, 31 are formed on a circuit board such as a printed circuit board (not shown). The terminal portion 14 and the electrode 6 are connected (joined) to the current-carrying patterns 30, 31, respectively, by means of solder or the like. A current path is formed by the current-carrying pattern 30, the shunt resistor 1, and the current-carrying pattern 31. In this embodiment, the voltage measuring device 26 can be used to measure the potential difference between the voltage detection wiring 25 and the lead wire 33 (i.e., the potential difference in the resistor 5). A current value is calculated by measuring the potential difference. The calculated current value is used to control, for example, various devices mounted on an automobile.

[0028] Fig. 5 is a diagram illustrating measurement positions of resistance and TCR to verify the effectiveness of the shunt resistor 1 having the slits 20 according to this embodiment. Fig. 6 is a graph showing the change in resistance of the shunt resistor 1 depending on the measurement position. Fig. 7 is a graph showing the change in TCR of the shunt resistor 1 depending on the measurement position.

[0029] Fig. 6 shows the simulation results of the resistance value when the width of the slit 20 (1.5mm to 4.5mm) and the measurement position (1.5mm, 3.0mm, 3.7mm, 5.0mm) are changed. Fig. 7 shows the simulation results of the TCR when the width of the slit 20 (1.5mm to 4.5mm) and the measurement position (1.5mm, 3.0mm, 3.7mm, 5.0mm) are changed.

[0030] In this embodiment, the set resistance value of the shunt resistor 1 is 100 μΩ. When the position 0 mm is set as the reference position (the center position of the electrode member 10 on the center line CL (see FIG. 1)), the measurement position of the resistance value and TCR corresponds to the distance from this reference position to the slit side end 23.

[0031] The horizontal axis of FIG. 6 indicates the measurement position of the resistance value, and the vertical axis of FIG. 6 indicates the resistance value [mΩ]. As is clear from FIG. 6, at a position closer to the reference position of the electrode member 10, the greater the width of the slit 20, the greater the resistance value. The farther the measurement position is from the reference position of the electrode member 10, the smaller the resistance value. Therefore, the resistance value can be changed by changing the width of the slit 20. On the other hand, at the position of the slit side end 23 rather than the position of the slit 20, the resistance value decreases as the width of the slit 20 increases, but does not change significantly.

[0032] For this reason, when the voltage detection wiring 25 is connected (bonded) to a position closer to the reference position than the position of the slit 20, the resistance value characteristics change depending on the connection position of the voltage detection wiring 25. On the other hand, when the voltage detection wiring 25 is connected (bonded) to a position closer to the slit side end 23 than the position of the slit 20, the resistance value characteristics hardly change depending on the connection position of the voltage detection wiring 25. Therefore, in order to suppress variation in the characteristics of the shunt resistor 1, it is desirable to connect the voltage detection wiring 25 to a position closer to the slit side end 23 than the position of the slit 20.

[0033] 6, the resistance value can be changed depending on the position where the slit 20 is formed. That is, if the slit 20 is formed at a position closer to the reference position, the resistance value becomes large, and if the slit 20 is formed at a position closer to the slit-side end 23, the resistance value becomes small.

[0034] The horizontal axis of FIG. 7 indicates the measurement position of the TCR, and the vertical axis of FIG. 7 indicates the TCR [ppm / deg]. As is clear from FIG. 7, at a position on the reference position side of the electrode member 10, the larger the width of the slit 20, the more positive the TCR. The farther the measurement position is from the reference position of the electrode member 10, the more negative the TCR. Therefore, the TCR can be changed by changing the width of the slit 20. On the other hand, at the position of the slit side end 23, if the width of the slit 20 is larger than the position of the slit 20, the TCR becomes negative. The TCR hardly changes even if the measurement position is changed.

[0035] For this reason, when the voltage detection wiring 25 is connected (bonded) to a position closer to the reference position than the position of the slit 20, the TCR characteristics change depending on the connection position of the voltage detection wiring 25. On the other hand, when the voltage detection wiring 25 is connected (bonded) to a position closer to the slit side end 23 than the position of the slit 20, the TCR characteristics hardly change depending on the connection position of the voltage detection wiring 25. Therefore, in order to suppress variation in the characteristics of the shunt resistor 1, it is desirable to connect the voltage detection wiring 25 to a position closer to the slit side end 23 than the position of the slit 20.

[0036] As is clear from Fig. 7, the TCR characteristics can be changed by changing the width of the slit 20. In particular, as shown in Fig. 7, the TCR characteristics resulting from changing the width of the slit 20 change more significantly at the position of the slit side end 23 than at the position on the reference position side.

[0037] 7, the TCR can be changed depending on the position where the slit 20 is formed. That is, when the slit 20 is formed at a position on the reference position side, the TCR is adjusted to the positive side, and when the slit 20 is formed at a position on the slit-side end 23 side, the TCR is adjusted to the negative side.

[0038] The additional effect of forming the slit 20 is as follows. In the shunt resistor of Patent Document 1 (i.e., JP 2018-170478 A), one method of changing the resistance value is to cut the resistor. For example, by cutting the side of the resistor, the cross-sectional area (i.e., the current path) of the resistor is reduced to increase the resistance value. However, this method may cause residual stress in the resistor. Such residual stress may cause the resistance value to fluctuate after mounting on the circuit board. According to this embodiment, the resistance value can be changed by forming the slit 20 without cutting the resistor 5. Therefore, the resistance value does not fluctuate due to the residual stress.

[0039] 8 and 9 are diagrams showing another embodiment of the shunt resistor 1. The configuration of this embodiment that is not particularly described is the same as that of the above-mentioned embodiment, so duplicated description will be omitted. As shown in Figs. 8 and 9, the electrode member 50 has a smaller size than the electrode member 10 according to the above-mentioned embodiment. More specifically, the electrode member 50 has a shorter length in the first direction than the electrode member 10.

[0040] The electrode member 50 has a contact portion 50a over its entirety that contacts the resistor 5. By moving the electrode member 50 in the direction shown by the outlined arrow in Fig. 8, the contact portion 50a of the electrode member 50 is connected to the resistor 5 (see Fig. 9). As shown in Fig. 9, the electrode member 50 has the same size as the resistor 5 and the electrode 6.

[0041] The surface of the electrode member 50 (the surface surrounded by the dotted line in FIG. 9 (in other words, the entire surface of the contact portion 50a)) is subjected to a surface treatment (e.g., NiP plating, Ni plating, etc.) that enables bonding. The electrode 6 is subjected to a surface treatment such as Sn plating, Ni plating, etc. to enable solder mounting.

[0042] As in the above-described embodiment, the slit 20 is a long hole extending in a direction perpendicular to the current direction. The contact portion 50a of the electrode member 50 has a first surface 51 adjacent to the resistor 5 and a second surface 52 opposite to the first surface 51, and the slit 20 is a through hole connected to the first surface 51 and the second surface 52.

[0043] Fig. 10 is a diagram showing an embodiment of a shunt resistance device 100 configured by mounting the shunt resistor shown in Fig. 9 on the mounting land pattern shown in Fig. 3. In the embodiment shown in Fig. 10, the shunt resistance device 100 includes a voltage detection wiring 25 and a current wiring 55 connected to an electrode member 50.

[0044] 10, the voltage detection wiring 25 is disposed in a wiring area A1 (a frame surrounded by a dotted line) between the slit 20 and the slit-side end 53. The current wiring 55 is disposed in a wiring area A2 (a frame surrounded by a dotted line) on the opposite side of the slit 20 from the wiring area A1. This wiring area A2 is the area between the slit 20 and the opposite end 54.

[0045] 10, the current wiring 55 is a plurality of bonding wires (four in FIG. 10), but the number of the current wirings 55 is not limited to this embodiment. The current wiring 55 is connected to the current-carrying pattern 30 and the electrode member 50. A current path is formed by the current-carrying pattern 30, the current wiring 55, the shunt resistor 1, and the current-carrying pattern 31.

[0046] Fig. 11 is a diagram showing another embodiment of the shunt resistance device 100 configured by mounting the shunt resistor shown in Fig. 9 on the mounting land pattern shown in Fig. 3. In the embodiment shown in Fig. 11, the shunt resistance device 100 includes a current wiring 56 configured from a clip-shaped terminal instead of the current wiring 55 configured from a plurality of bonding wires. As shown in Figs. 10 and 11, the shunt resistance device 100 may include at least one of a plurality of bonding wires and a clip-shaped terminal as the current wiring.

[0047] The above-described embodiments have been described for the purpose of enabling a person having ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments are naturally possible for a person skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope according to the technical idea defined by the claims. [Explanation of symbols]

[0048] 1 Shunt resistor 5 Resistor 5a 1st resistor surface 5b Second resistor surface 6 electrodes 10 Electrode material 10a Contact area 11 Main body 14 Terminal section 20 Slit 21 Page 1 22 Side 2 23 Slit side end 24 Opposite end 25 Voltage detection wiring 26 Voltage measuring device 30 Current Pattern 31 Current Pattern 33 Lead Line 50 Electrode material 50a Contact area 51 Page 1 52 Side 2 53 Slit side end 54 Opposite end 55 Current wiring 56 Current wiring

Claims

1. A shunt resistor comprising an electrode member, an electrode, and a resistor, each made of a conductive material, the resistor is a plate having a thickness and has a first resistor surface and a second resistor surface; The electrode member is A contact portion that contacts the resistor; A slit is formed in the contact area, the contact portion has a first surface adjacent to the resistor and a second surface opposite the first surface; A shunt resistor, wherein the contact portion, the resistor, and the electrode are stacked in the thickness direction, so that the first surface is connected to a surface of the first resistor, and the electrode is connected to a surface of the second resistor.

2. The shunt resistor according to claim 1 , wherein the slit is elongated in a direction perpendicular to a current direction.

3. A shunt resistor as described in claim 1 or claim 2, wherein the slit is a through hole penetrating the first surface and the second surface.

4. The device includes a resistor, an electrode member, an electrode, and a voltage detection wiring connected to the electrode member, the resistor is a plate having a thickness and has a first resistor surface and a second resistor surface; the electrode member has a contact portion that contacts the resistor, the contact portion has a first surface adjacent to the resistor and a second surface opposite the first surface; By stacking the contact portion, the resistor, and the electrode in a thickness direction, the first surface is connected to a surface of the first resistor, and the electrode is connected to a surface of the second resistor, The electrode member has a slit formed in the contact portion, The voltage detection wiring is disposed in a first wiring region between the slit and a slit side end of the electrode member.

5. The shunt resistor device includes a current wiring connected to the electrode member, The shunt resistor device according to claim 4 , wherein the current wiring is arranged in a second wiring region on an opposite side to the first wiring region across the slit.

6. The shunt resistor device according to claim 4 or 5, wherein the slit is elongated in a direction perpendicular to a current direction.

7. A shunt resistor device described in any one of claims 4 to 6, wherein the slit is a through hole penetrating the first surface and the second surface.

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