Shunt resistor

Abstract

To provide a shunt resistor that can monitor the status.SOLUTION: A shunt resistor 1 includes at least two laminated elements 50 including resistors 5 attached to an electrode member 10. The electrode member 10 includes at least two contact portions 10a that are in contact with the at least two laminated elements 50.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] There is a shunt resistor that passes current through a resistor body and detects the magnitude of the current from the voltage across both ends thereof (see, for example, Patent Document 1). Such a shunt resistor includes a disc-shaped resistor body and two electrodes formed on both surfaces of the resistor body. 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

Summary of the Invention

Problems to be Solved by the Invention

[0004] The electrode connected to the bonding wire has a potential distribution. Therefore, when the connection position of the bonding wire is displaced, the detected resistance value and the resistance temperature coefficient (TCR) of the shunt resistor may change. The resistance temperature coefficient is an index indicating the rate of change of the resistance value with temperature.

[0005] In the surface-mounted shunt resistor as described above, its state (such as the presence or absence of a fault and the risk of a fault) cannot be grasped. Therefore, even when the shunt resistor fails or may fail due to the application of a large current or the like, the failure of the shunt resistor cannot be predicted or detected.

[0006] Therefore, an object of the present invention is to provide a shunt resistor and a shunt resistor device capable of grasping the state. [Means for solving the problem]

[0007] In one embodiment, a shunt resistor is provided, comprising an electrode member made of a conductive material and at least two stacked elements each having a resistor attached to the electrode member. The electrode member has at least two contact portions that contact the at least two stacked elements.

[0008] In one embodiment, the electrode member is provided with an electrode member-side slit formed in the contact portion. In one embodiment, the laminated element includes a first electrode positioned on the opposite side of the electrode member, with the resistor in between. In one embodiment, the laminated element includes a second electrode disposed between the resistor and the electrode member.

[0009] In one embodiment, the laminated element is provided with a laminated element-side slit formed in the second electrode. In one embodiment, the electrode member has a structure that allows adjustment of the temperature coefficient of resistance, which is an index indicating the rate of change in resistance due to temperature, by its thickness.

[0010] In one embodiment, a shunt resistor device is provided comprising the shunt resistor, at least two voltage detection wires connected to the at least two contact portions, and at least two voltage detection wires connectable to an inner region of a current-carrying pattern for mounting the at least two multilayer elements. The current-carrying pattern has notches formed in the inner region.

[0011] In one embodiment, the electrode member is provided with an electrode member-side slit formed in the contact portion, and each of the at least two voltage detection wires connected to the at least two contact portions is arranged in the wiring region between the electrode member-side slit and the end of the electrode member. [Effects of the Invention]

[0012] By arranging at least two laminated elements, the state of the shunt resistor can be grasped.

Brief Description of the Drawings

[0013] [Figure 1] It is a perspective view showing an embodiment of a shunt resistor for current detection. [Figure 2] It is a longitudinal sectional view of the shunt resistor shown in FIG. 1. [Figure 3] It is a diagram showing a shunt resistor mounted on a mounting land pattern. [Figure 4] FIGS. 4(a) and 4(b) are diagrams showing other embodiments of the electrode member. [Figure 5] FIGS. 5(a) and 5(b) are diagrams showing other embodiments of the energization pattern. [Figure 6] It is a diagram showing a current path formed by the energization pattern and the shunt resistor. [Figure 7] It is a diagram showing a current path formed by the energization pattern and the shunt resistor. [Figure 8] It is a diagram showing a current path formed by the energization pattern and the shunt resistor. [Figure 9] It is a diagram showing a current path formed by the energization pattern and the shunt resistor. [Figure 10] It is a diagram showing another embodiment of the shunt resistor. [Figure 11] It is a diagram showing another embodiment of the shunt resistor. [Figure 12] It is a diagram showing a slit formed in the second electrode.

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are denoted by the same reference numerals and redundant descriptions are omitted.

[0015] FIG. 1 is a perspective view showing an embodiment of a shunt resistor for current detection. FIG. 2 is a longitudinal sectional view of the shunt resistor shown in FIG. 1. As shown in FIGS. 1 and 2, the shunt resistor 1 includes an electrode member 10 made of a conductive material and at least two laminated elements 50 attached to the electrode member 10. In the embodiment shown in FIGS. 1 and 2, the shunt resistor 1 includes two laminated elements 50, but may include three or more laminated elements 50.

[0016] The laminated element 50 includes a plate-shaped (thin plate-shaped) resistor 5 having a predetermined thickness and width, and a plate-shaped (thin plate-shaped) electrode (first electrode) 6A made of a conductive material. The electrode 6A is disposed on the opposite side of the electrode member 10 with the resistor 5 interposed therebetween.

[0017] Examples of the material of the resistor 5 include resistance alloy materials such as Cu-Mn-Ni alloys and Ni-Cr alloys. An example of the material of the electrode 6A and the electrode member 10 is copper (Cu), a highly conductive metal.

[0018] The resistor 5 has a first resistor surface 5a and a second resistor surface 5b that 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 6A is connected to the second resistor surface 5b. That is, the electrode 6A, the resistor 5, and the electrode member 10 are laminated in this order in the thickness direction of the shunt resistor 1.

[0019] In FIGS. 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 and is parallel to the current direction of the current passing through the shunt resistor 1. The second direction is the width direction of the shunt resistor 1 and is perpendicular to the first direction.

[0020] The electrode member 10 has contact portions 10a that contact the multilayer element 50 (in this embodiment, the resistor 5 and the electrode 6A). The number of contact portions 10a corresponds to the number of multilayer elements 50. In this embodiment, since the shunt resistor 1 has two multilayer elements 50, the electrode member 10 has two contact portions 10a.

[0021] The two stacked elements 50 are arranged symmetrically with respect to the center line CL of the electrode member 10, and are arranged in series with respect to the electrode member 10, but spaced apart, in the first direction of the shunt resistor 1. 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. The electrode member 10 has both ends 23 in the first direction.

[0022] The electrode member 10 may be connected to the first resistive surface 5a of the resistor 5 by a conductive adhesive such as metal nanoparticles (silver paste using silver nanoparticles or copper paste using copper nanoparticles), welding such as pressure welding, or soldering. The electrode 6A may be connected to the second resistive surface 5b of the resistor 5 by a similar connection. The electrode 6A is surface-treated with Sn plating or Ni plating to enable solder mounting. Surface plating of the electrode 6A is not required.

[0023] The electrode member 10 has a structure that allows adjustment of the temperature coefficient of resistance (TCR), which is an index indicating the rate of change in resistance due to temperature, by adjusting its thickness. More specifically, the accuracy of the TCR can be improved by adjusting the thickness of the electrode member 10. For example, the TCR can be lowered by making the electrode member 10 thinner. In one embodiment, the electrode member 10 may have the same thickness as the resistor 5, or it may have a thinner thickness than the resistor 5.

[0024] As shown in Figures 1 and 2, the electrode member 10 is provided with a slit (more specifically, an electrode member-side slit) 20A formed in the contact portion 10a. By forming a slit in the contact portion 10a of the electrode member 10 in this way, the TCR can be adjusted. In this embodiment, the slit 20A is an elongated hole extending in a direction perpendicular to the current direction (i.e., parallel to the second direction) and penetrates from the surface of the electrode member 10 to the resistor 5. In one embodiment, the slit 20A may be a recess formed on the surface of the electrode member 10. Each of the two ends 23 is adjacent to the slit 20A formed in the contact portion 10a.

[0025] Figure 3 shows a shunt resistor mounted on a mounting land pattern. As shown in Figure 3, the shunt resistor 1 has a wiring area AR (the frame enclosed by the dotted line in Figure 3) located between the slit 20A and both ends 23. The wiring area AR constitutes part of the contact area 10a, and one end of the voltage detection wiring 25 is connected to the wiring area AR during mounting. The other end of the voltage detection wiring 25 is connected to the connector 35.

[0026] Figures 4(a) and 4(b) show other embodiments of the electrode member. As shown in Figure 4(a), the electrode member 10 may have a slit 20A formed in one of its two contact portions 10a. As shown in Figure 4(b), the electrode member 10 may not have a slit 20A. In the embodiment shown in Figure 4(b), the wiring region AR is formed in the region adjacent to both ends 23.

[0027] The voltage detection wiring 25 is a wiring (terminal) for detecting the potential difference between the electrode member 10 and the voltage detection wiring 33. The multilayer element 50, the electrode member 10, and the voltage detection wiring 25 connected to the electrode member 10 constitute a shunt resistor device 100.

[0028] The number of voltage detection wires 25 corresponds to the number of multilayer elements 50. Therefore, the shunt resistor device 100 has at least two voltage detection wires 25 connected to at least two contact portions 10a. In one embodiment, the voltage detection wires 25 may be bonding wires. In this case, the wiring region AR of the electrode member 10 (more specifically, the contact portion 10a) is subjected to a surface treatment that enables bonding (e.g., NiP plating or Ni plating). Surface treatment of the electrode member 10 is not required.

[0029] As shown in Figure 3, the shunt resistors 1 are arranged on adjacent current-carrying patterns 30. Voltage detection wiring (leader wires) 33 are arranged between the current-carrying patterns 30. The leader wires 33 are voltage detection terminals for detecting the potential difference that occurs between them and the electrode members 10. The current-carrying patterns 30 are formed on a circuit board such as a printed circuit board (not shown). The multilayer element 50 (more specifically, electrode 6A) is connected (bonded) to the current-carrying patterns 30 by means of soldering or other means.

[0030] The energizing pattern 30 has a main body portion 30a, an inner region 30b located inside the main body portion 30a, and a notch portion 30c formed in the inner region 30b that demarcates the main body portion 30a and the inner region 30b. In the embodiment shown in Figure 3, the notch portion 30c completely separates the main body portion 30a and the inner region 30b, and the stacked element 50 is connected to the inner region 30b and a part of the main body portion 30a of the energizing pattern 30. The lead wire 33 is connected to the inner region 30b of the energizing pattern 30.

[0031] Figures 5(a) and 5(b) show other embodiments of the current-carrying pattern. In the embodiment shown in Figure 5(a), the notch 30c has an arc shape and completely separates the main body 30a and the inner region 30b. In the embodiment shown in Figure 5(b), the notch 30c has an L shape and the main body 30a and the inner region 30b are connected. The lead wire 33 is not directly connected to the inner region 30b of the current-carrying pattern 30, but is spaced apart. Note that the electrode 6A shown in the figure is the electrode when the multilayer element 50 is connected to the current-carrying pattern.

[0032] Figures 6 to 9 show the current path formed by the current-carrying pattern and the shunt resistor. A voltage detection wire 25 is connected to the electrode member 10 of the shunt resistor 1, and a lead wire 33 is connected to the current-carrying pattern 30, forming a current path that flows from the current-carrying pattern 30 in the thickness direction of the shunt resistor 1. In this embodiment, a voltage measuring device 26 is used to measure the potential difference between the voltage detection wire 25 and the lead wire 33 (i.e., the potential difference in the resistor 5). The current value is calculated by measuring this potential difference.

[0033] According to this embodiment, the shunt resistor 1 comprises at least two multilayer elements 50 and is configured to measure the potential difference in each multilayer element 50. If an abnormality occurs in the shunt resistor 1, the resistance value of the abnormal multilayer element 50 changes. According to this embodiment, by arranging at least two multilayer elements 50 and comparing the resistance values ​​of multiple multilayer elements 50, the state of the shunt resistor 1 can be determined. Therefore, even if the shunt resistor 1 has failed or is likely to fail, the failure of the shunt resistor 1 can be predicted or detected.

[0034] In the embodiment shown in Figure 6, the shunt resistor 1 has a number of slits 20A corresponding to the number of multilayer elements 50, and the current-carrying pattern 30 has a number of notches 30c corresponding to the number of multilayer elements 50. In the embodiment shown in Figure 7, the shunt resistor 1 has a single slit 20A, and the current-carrying pattern 30 has a single notch 30c. In the embodiment shown in Figure 8, the shunt resistor 1 has a number of slits 20A corresponding to the number of multilayer elements 50, but the current-carrying pattern 30 does not have a notch 30c. In the embodiment shown in Figure 9, the shunt resistor 1 does not have a slit 20A, and the current-carrying pattern 30 has a number of notches 30c corresponding to the number of multilayer elements 50.

[0035] Figure 10 shows another embodiment of the shunt resistor. In the embodiment described above, the shunt resistor 1 has at least one of the slit 20A and the notch 30c, but as shown in Figure 10, the shunt resistor 1 does not have to have either the slit 20A or the notch 30c.

[0036] Figure 11 shows another embodiment of the shunt resistor. As shown in Figure 11, the multilayer element 50 may include an electrode (second electrode) 6B positioned between the resistor 5 and the electrode member 10.

[0037] Figure 12 shows a slit formed in the second electrode. As shown in Figure 12, the laminated element 50 may have a laminated element-side slit 20B formed in the second electrode 6B. In the embodiment shown in Figure 12, the electrode member-side slit 20A and the laminated element-side slit 20B penetrate to reach the resistor 5, but in one embodiment, the electrode member-side slit 20A may be a recess formed on the surface of the electrode member 10. Alternatively, the electrode member-side slit 20A may be a through hole to the second electrode 6B. Since the TCR is affected by the width, length, and formation position of the slit, it is desirable to form it in a way that ensures a good TCR. In the embodiment shown in Figure 12, the current-carrying pattern 30 does not have a notch 30c, but it may have a notch 30c.

[0038] The embodiments described above are intended to enable persons with ordinary skill in the art to implement the present invention. Various modifications of the above embodiments can be made naturally by those skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments as well. Therefore, the present invention is not limited to the embodiments described, but is to be interpreted in the broadest sense according to the technical idea defined by the claims. [Explanation of Symbols]

[0039] 1. Shunt resistor 5 Resistors 5a 1st resistor surface 5b Second resistor surface 6A 1st electrode 6B 2nd electrode 10 Electrode members 10a Contact area 20A Slit (Electrode Member Side Slit) 20B Slit (Slit on the multilayer element side) 23 Both ends 25 Voltage detection wiring 26 Voltage measuring device 30 power supply patterns 30a Main body 30b Inner area 30c cut section 33 Voltage detection wiring (lead wire) 35 connectors 50 stacked elements 100 Shunt Resistors CL center line AR wiring area

Claims

1. An electrode member made of a conductive material, The electrode member is attached to at least two stacked elements, each having a resistor, The electrode member has at least two contact portions that contact the at least two stacked elements, The aforementioned multilayer element has a structure in which the resistor is sandwiched between the first electrode and the second electrode. The electrode member has a surface facing the current-carrying pattern on which the two stacked elements are mounted. The second electrode of each stacked element is connected to the contact portion on the surface. The first electrode is connected to the current flow pattern, A shunt resistor device in which the current-carrying pattern, the first electrode, the resistor, the second electrode, and the electrode member are stacked in the thickness direction.

2. The shunt resistor device according to claim 1, wherein the electrode member is provided with an electrode member-side slit formed at the contact portion.

3. The shunt resistor device according to claim 1, wherein the laminated element is provided with a laminated element-side slit formed in the second electrode.

4. The shunt resistor device according to claim 1, wherein the electrode member has a structure that allows adjustment of the temperature coefficient of resistance, which is an index indicating the rate of change in resistance value due to temperature, by its thickness.

5. A shunt resistor according to claim 1 or claim 2, At least two voltage detection wires connected to the surface opposite to the surface of the at least two contact portions, The system comprises at least two voltage detection wires that can be connected to the inner region of the energizing pattern, The current-carrying pattern has a notch formed in the inner region, comprising a shunt resistor device.

6. The electrode member is provided with an electrode member side slit formed in the contact portion, The shunt resistor device according to claim 5, wherein each of the at least two voltage detection wires connected to the at least two contact portions is located in the wiring region between the electrode member side slit and the end of the electrode member.

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