Current detection multilayer resistors

Abstract

To provide a lamination type resister which achieves stabilization of a resistance characteristic.SOLUTION: A lamination type resister comprises: a resister constructed by a resistance material; and two electrodes nipping the resister. In the resister which is formed in a thin shape for detecting a high-frequency current and is formed by reducing a self-inductance value, the resistance material for detecting the current is constructed by: a metal body made of a metal material such as nichrome having a conductivity; and an insulation particle made of an insulation material such as alumina. A resister formed by mixing the metal body and the insulation particle is exposed to an end surface of the lamination type resister, and contains: a particle having an insulation property; and a three-dimensional net type metal body surrounding the particle. A rate of the metal body against the resistance material is 30 vol% or more and 80 vol% or less.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention provides a method for detecting current For current detection This relates to multilayer resistors. [Background technology]

[0002] Patent Document 1 discloses a resistive material in which flat metal particles are added at a predetermined ratio to an insulating matrix material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-019685 Summary of the Invention [Problem to be solved by the invention]

[0004] In the resistive materials described above, the matrix material is an insulator, which increases the electrical resistance. However, unless the metal particles are flattened, it is difficult to secure a path for current to flow, and the contact state between the metal particles is likely to change depending on the usage conditions.

[0005] For example, there is a concern that the resistance value of the resistive material may fluctuate due to changes in the contact state caused by temperature changes in the resistive material, or due to dielectric breakdown when a high voltage is applied to the resistive material. In this way, resistive materials whose matrix material is an insulator are prone to unstable resistance characteristics.

[0006] The present invention has been made in view of these problems, and has as its object to provide a multilayer resistor that stabilizes the resistance characteristics. [Means for solving the problem]

[0007] According to one aspect of the present invention, cornerA current detection multilayer resistor is configured as a laminated structure including a plate-shaped resistor having a first plane and a second plane in a thickness direction, a first electrode formed on the first plane, a second electrode formed on the second plane, and the resistor, the first electrode, and the second electrode, and is mounted on a wiring pattern or a power semiconductor for current detection, the resistor has a length on the first plane and the second plane that is greater than a length in a stacking direction of the stacked structure, The resistor is made of a resistive material having a specific resistance of 200 μΩ·cm or more and 300,000 μΩ·cm or less, and is formed by mixing a metal body made of a conductive metal material with insulating particles made of an insulating material, and the resistor is exposed at an end face of the current detection multilayer resistor, and the end face of the current detection multilayer resistor is shaped so that the first electrode, the second electrode and the resistor are flush with each other. A current sensing stacked resistor is provided. [Effects of the Invention]

[0008] According to this aspect, the three-dimensional mesh structure of the metal body makes it easier to form a conductive path within the resistance material, thereby stabilizing the resistance characteristics. [Brief explanation of the drawings]

[0009] [Figure 1A] FIG. 1A is a diagram showing an example of the configuration of a resistor according to an embodiment of the present invention. [Figure 1B] FIG. 1B is a cross-sectional view taken along line II-II in FIG. 1A. [Figure 2] FIG. 2 is a diagram showing an example of a method for manufacturing a resistor. [Figure 3] FIG. 3 is a diagram showing another example of a method for manufacturing a resistor. [Figure 4] FIG. 4 is a diagram illustrating the shape of metal powder for producing a resistance material. [Figure 5] FIG. 5 is a diagram showing an example of the structure of the resistive material in this embodiment. [Figure 6] FIG. 6 is a diagram showing another example of the structure of the resistive material in this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] [Resistor Description] First, the structure of a resistor 1 of this embodiment will be described with reference to FIGS. 1A and 1B.

[0012] FIG. 1A is a perspective view showing the structure of a resistor 1 in this embodiment, and FIG. 1B is a cross-sectional view of the resistor 1 taken along line II-II in FIG. 1A.

[0013] The resistor 1 is a resistor for detecting current, and is called a current detection resistor or a shunt resistor. The resistor 1 is mounted in, for example, a power module and used for detecting large currents.

[0014] In order to improve the accuracy of detecting high-frequency currents, the resistor 1 of this embodiment is formed to be thin and have a small self-inductance value. The resistor 1 is formed in a disk shape and includes a resistive element 11 made of a resistive material, and two electrodes 21 and 22 that sandwich the resistive element 11.

[0015] The thickness t1 of the resistor 11 is set to, for example, several millimeters (mm) or less so that the self-inductance value of the resistor 1 is small. In this embodiment, the thickness t1 of the resistor 11 is 0.2 mm. Furthermore, in order to facilitate mounting on a wiring pattern or a power semiconductor, the diameter R of the resistor 11 is set to, for example, several mm so that it is larger than the thickness t1 of the resistor 11. In this embodiment, the diameter R of the resistor 11 is 3 mmφ.

[0016] In this embodiment, a current path is formed in the thickness direction of the resistor 11, which is shorter than the current path of a general shunt resistor. Therefore, the resistivity (volume resistance value) of the resistor 11 is set to a value larger than the resistivity of the alloy alone used as a resistance material of a general shunt resistor.

[0017] For example, when resistor 1 is used to detect large currents, it is expected that the resistance value of resistor 11 will be set to a value in the range of 50 μΩ to 1,000 μΩ. Therefore, the resistive material that constitutes resistor 11 is preferably one that can be designed to have a specific resistance (volume resistivity) in the range of 200 μΩ·cm (microohm centimeters) to 300,000 μΩ·cm.

[0018] The resistive material as described above is formed by mixing conductive metal powder and insulating particles so that the resistivity of resistor 11 is greater than the resistivity (50 μΩ·cm to 100 μΩ·cm) of resistors in general shunt resistors.

[0019] The two electrodes 21 and 22 are electrodes for passing a current in the thickness direction of the resistor 11, and are made of a highly conductive metal material. The electrodes 21 and 22 are formed on both sides of the resistor 11, and the electrode formed on one side of the resistor 11 is called the first electrode 21, and the electrode formed on the other side is called the second electrode 22.

[0020] The thickness t2 of each of the electrodes 21 and 22 is made thin to reduce the height of the resistor 1. For example, the thickness t2 is made thinner than the thickness t1 of the resistive element 11. In this embodiment, the thickness t2 of each of the electrodes 21 and 22 is 0.1 mm.

[0021] In this way, the resistor 1 has a small thickness h while maintaining the resistance required for current detection, thereby reducing the self-inductance value. Therefore, it is possible to suppress high-frequency current detection errors caused by the inductance of the resistor 1.

[0022] [Resistance material explanation] The resistive material 11a is composed of insulating particles and a three-dimensional mesh-like metal body surrounding the insulating particles so that the resistivity of the resistive body 11 is higher than that of resistors in general shunt resistors. The resistive material 11a is a sintered body obtained by sintering metal powder and insulating particles to form the metal body.

[0023] The metal powder before sintering preferably has an aspect ratio of 1.0 to 2.0, and the metal powder preferably has a particle size of 0.5 μm to 20 μm, and the insulating particles preferably have a particle size of 0.1 μm to 10 μm.

[0024] Here, the metal bodies and insulating particles that make up the resistive material 11a will be described.

[0025] <Metal body> The metal body of the resistive material 11a may be a resistive material of a general shunt resistor. From the viewpoint of ensuring the stability of the resistance characteristics, a metal material suitable for detecting a large current, such as an alloy whose resistance value of the resistive material 11 changes little with temperature change, is preferred.

[0026] Specific examples include at least one alloy selected from resistance materials such as nichrome, Manganin (registered trademark), Zeranin (registered trademark), and copper-nickel. In particular, it is preferable to use nichrome from the viewpoint of ensuring the resistance value of the resistance material. Furthermore, it is preferable to use Manganin (registered trademark) from the viewpoint of workability. Thus, it is preferable to form the metal body of the resistance material 11a using at least one selected from the group consisting of nichrome, copper-manganese, and copper-nickel.

[0027] Nichrome here refers to a Ni-Cr alloy or an alloy containing it as the main component, copper manganese refers to a Cu-Mn alloy or an alloy containing it as the main component, and copper nickel refers to a Cu-Ni alloy or an alloy containing it as the main component. Manganin (registered trademark) refers to a Cu-Mn-Ni alloy or an alloy containing it as the main component, and Zeranin (registered trademark) refers to a Cu-Mn-Sn alloy or an alloy containing it as the main component.

[0028] The ratio of the metal bodies contained in the resistive material 11a is 30 vol% or more and 80 vol% or less. If the ratio of the metal bodies is less than 30 vol%, the resistive material 11a will not be able to secure a current path and will no longer function as a resistive material. On the other hand, if the ratio of the metal bodies exceeds 80 vol%, the resistivity of the resistive material 11a will decrease to a value almost equal to the resistivity of the metal bodies alone.

[0029] <Insulating particles> On the other hand, the insulating particles of the resistance material 11a can be made of a ceramic material that has excellent heat resistance as well as insulating properties. For example, in order to prevent cracks from occurring at the joint due to thermal stress, at least one ceramic material selected from the group consisting of aluminum oxide (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4), and zirconia (ZrO2) can be used. Hereinafter, aluminum oxide and aluminum nitride will be referred to as alumina and aluminum nitride, respectively.

[0030] Among the above ceramic materials, alumina, which is widely used as an insulating material, is preferred from the viewpoints of heat dissipation and heat cycle durability. Furthermore, for applications requiring higher heat dissipation, it is preferred to select aluminum nitride, which has high thermal conductivity, and for applications requiring high heat cycle durability, it is preferred to select silicon nitride.

[0031] A method for manufacturing the resistor 1 will now be briefly described with reference to FIGS.

[0032] FIG. 2 is a diagram for explaining an example of a method for manufacturing the resistor 1 according to this embodiment.

[0033] First, a disk-shaped resistance material 11a, and disk-shaped electrode materials 21a and 22a are prepared. The electrode materials 21a and 22a are made of a highly conductive metal material such as copper (Cu).

[0034] As shown in Fig. 2(a), a disk-shaped electrode material 21a, a disk-shaped resistance material 11a, and a disk-shaped electrode material 22a are stacked in this order. These stacked materials are joined by, for example, pressure welding or sintering, to form a laminated structure 1a as shown in Fig. 2(b).

[0035] Next, as shown in Fig. 2(c), the laminated structure 1a is punched into individual pieces in a circular shape using a processing method such as a punch, thereby forming the disk-shaped resistor 1 as shown in Fig. 2(d).

[0036] Although the resistor 1 is formed in a disk shape in this embodiment, the resistor 1 may be formed in a polygonal shape such as a triangle or a square. A manufacturing method for forming the resistor 1 in a rectangular plate shape will be described below.

[0037] 3A to 3C are diagrams illustrating another example of the method for manufacturing the resistor 1 according to this embodiment. The steps from Fig. 3A to Fig. 3B are the same as the steps from Fig. 2A to Fig. 2B.

[0038] After the laminated structure 1a is formed as shown in Fig. 3(b), it is cut into individual pieces by a processing method such as dicing into a rectangular shape as shown in Fig. 3(c), thereby forming rectangular plate-shaped resistors 1 as shown in Fig. 3(d).

[0039] Next, a method for manufacturing the resistance material 11a in this embodiment will be described.

[0040] The manufacturing method of the resistive material 11a includes a mixing step of mixing a conductive metal powder (metal powder) with an insulating powder (insulating powder), and a sintering step of sintering the mixed powder obtained by mixing while applying pressure to the mixed powder by a uniaxial pressing method at a predetermined temperature.

[0041] In the mixing step, it is preferable that the metal powder used is a powder of a metal having a melting point lower than that of the insulating powder, and that the metal powder is granulated so that the particle size is equal to or smaller than that of the insulating powder.

[0042] In the sintering process, the mixed powder is pressed by, for example, placing the container for the mixed powder in a near-vacuum state. The higher the pressing pressure, the lower the resistivity of the resistance material 11a, but the easier it is to ensure a conductive path (current path) through which current flows. Therefore, it is preferable to set the pressing pressure higher. The predetermined temperature is lower than the melting point of the metal powder, and is preferably set to a temperature about 15% lower than the melting point of the metal powder.

[0043] By the above-described manufacturing method, metal bodies are formed in a three-dimensional network between insulating particles in the resistance material 11a.

[0044] Next, the function and effect of the resistance material 11a in this embodiment will be described.

[0045] According to this embodiment, the resistive material 11a for detecting a current includes insulating particles and a three-dimensional mesh-like metal body surrounding the insulating particles, and the ratio of the metal body to the entire resistive material 11a is within the range of 30 vol% to 80 vol%.

[0046] Since the resistive material 11a contains insulating particles, the resistive material 11a has a higher resistivity than the metal body alone. In addition, the metal body of the resistive material 11a has a current path formed in a three-dimensional mesh shape surrounding the insulating particles, which makes it easier to ensure contact area between the metal particles and increases adhesion, resulting in stable resistance characteristics.

[0047] Furthermore, the current path is less likely to be interrupted by temperature changes or application of high voltage, and the influence on the resistivity of the entire resistive material 11a is reduced. Therefore, the resistivity of the resistive material 11a can be made larger than the resistivity of the metal body alone, while stabilizing the resistance characteristics of the resistive material 11a.

[0048] Furthermore, according to this embodiment, the conductive metal body of the resistance material 11a is formed using at least one metal powder selected from the group consisting of nichrome, copper-manganese, and copper-nickel. These metal powders are alloys used for current detection, and have small changes in resistance value due to temperature changes. Therefore, by using these alloys, it is easy to ensure the resistance value required for current detection and to suppress an increase in TCR.

[0049] Furthermore, according to this embodiment, the insulating particles are formed using at least one insulating powder selected from the group consisting of alumina, aluminum nitride, silicon nitride, and zirconia. These insulating powders are ceramic materials with low thermal expansion coefficients and are used as substrate materials. Therefore, by using these insulating powders, the thermal stress of the resistor 11 made of the resistive material 11a can be made closer to the thermal stress of the substrate. Therefore, the occurrence of cracks due to heat cycles between the resistor 11 and the substrate can be suppressed.

[0050] Furthermore, according to this embodiment, by forming the metal body of the resistive material 11a into a three-dimensional mesh structure, the TCR can be kept within the allowable range of 100 ppm or less, thereby making it possible to suppress a decrease in detection accuracy when detecting current using the resistor 1.

[0051] Furthermore, it is possible to design the resistivity of the resistive material 11a to be within the range of 200 μΩ·cm to 30,000 μΩ·cm, which makes it possible to ensure the resistance value required for current detection even with the vertical resistor 1 structure shown in FIG.

[0052] Furthermore, according to this embodiment, the resistive material 11a is formed by sintering a conductive metal powder and insulating particles, which makes it easier to form the metal body of the resistive material 11a into a three-dimensional mesh shape.

[0053] The aspect ratio of the metal powder before sintering is between 1.0 and 2.0, which gives the resistive material isotropic resistance, and therefore the orientation of the resistive material does not need to be considered when fabricating resistor 1, making it easy to process.

[0054] Furthermore, according to this embodiment, the resistor 11 is made of a resistive material 11a containing insulating particles in a conductive metal body, and two electrodes 21 and 22 sandwiching the resistive material 11a, and the metal body is continuously formed in the direction between the electrodes 21 and 22 in the resistor 11. As a result, many current paths are formed in the resistor 11 so as to avoid the insulating particles, and the resistivity of the resistor 11 can be increased while stabilizing the resistance characteristics of the resistor 11.

[0055] According to this embodiment, the resistive material 11a is manufactured by mixing insulating particles and metal powder, heating the mixed powder to a predetermined temperature lower than the melting point of the metal powder, and sintering the mixed powder under pressure, thereby forming a three-dimensional mesh-like metal body surrounding the insulating particles in the resistor 11.

[0056] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0057] For example, in the above embodiment, the electrodes 21 and 22 of the resistor 1 have the same area and thickness, but the electrodes 21 and 22 may be formed so that at least one of the area and thickness is different from each other. Also, through holes may be formed in the electrodes 21 and 22.

[0058] The electrodes 21 and 22 may be formed on both sides of the resistive material 11a by plating, vacuum deposition, ion plating, sputtering, vapor phase growth, cold spraying, or the like. [Example]

[0059] Next, a test specimen based on the resistance material 11a of this embodiment was prepared, and various measurements were carried out to evaluate the resistance characteristics of the resistance material 11a. The test specimen preparation method and its evaluation will be described below.

[0060] [Preparation of specimen] Alumina powder (ALM-41-01: manufactured by Sumitomo Chemical Co., Ltd.) was used as insulating powder for producing the resistance material 11a. Nichrome powder (powder D50 with a particle size of 6 μm produced by atomizing Evanome (registered trademark)) was used as metal powder for producing the resistance material 11a. Furthermore, as comparative examples, a test piece made of alumina alone and a test piece made of nichrome alone were prepared.

[0061] <Mixing / granulation> First, the above-mentioned two powders were weighed out in the mixing ratio shown in Table 1, and mixed and granulated using a mortar and pestle until the two powders were mixed almost uniformly.

[0062] The average particle size of each particle of the granulated mixed powder is as follows: Alumina powder: average particle size 2.2 μm ·Nichrome powder: average particle size 2.0μm

[0063] <Pressing and sintering> Next, the granulated mixed powder was placed in a carbon die with a diameter of 10 mm. Then, using a hot press (multipurpose high-temperature furnace Hi-Multi 5000: manufactured by Fuji Denpa Kogyo Co., Ltd.), the mixed powder in the carbon die was heated to a predetermined temperature lower than the melting point of nichrome, and sintered while applying pressure. The sintered specimen was a disk-shaped sintered body with a diameter of 10 mm and a thickness of 1.8 mm.

[0064] The hot pressing conditions were as follows: Atmosphere: 20 Pa or less Press pressure: 3.0kN~3.9kN Sintering temperature: 1000℃~1200℃ ·Holding time: 10 minutes

[0065] Several specimens were prepared by changing the ratio of alumina powder to nichrome powder. When preparing the specimens, the pressing pressure was changed as necessary for each ratio of alumina powder to nichrome powder.

[0066] [Evaluation method] The test specimens obtained as described above were subjected to the following evaluation tests.

[0067] <Shape of metal powder before sintering> Calculation of metal powder aspect ratio A scanning electron microscope (JSM-7000F: manufactured by JEOL Ltd.) was used, and the image was taken at 1,800x magnification. in The particles of nichrome powder (nichrome particles) were photographed, and the aspect ratio of the photographed nichrome particles was calculated.

[0068] The aspect ratio of the nichrome particles was determined by selecting any of the nichrome particles in the captured SEM image. Randomly select 20 particles, and calculate the length of the long side of each selected nichrome particle by dividing the length of the short side.

[0069] <Test specimen structure> A focused ion beam observation device (NB-5000: Hitachi High-Technologies Corporation) was used to observe the image at 10,000 magnification. in The cross section of the specimen was photographed.

[0070] <Resistance characteristics> Calculation of resistivity The resistance value of the test specimen was measured when the temperature of the test specimen was 25°C, and the resistivity was calculated based on this resistance value.

[0071] Specific resistance (μΩ cm) = resistance value (Ω) x area (cm 2 ) / Thickness (cm) Here, the area is 0.25π (cm 2 ) and the thickness is 0.18 (cm).

[0072] -Measurement of temperature coefficient of resistance The temperature coefficient of resistance (TCR) represents the rate at which the resistance value of a test piece changes due to a change in temperature. In shunt resistors, the larger the temperature coefficient of resistance, the greater the tendency for current detection errors to increase. The temperature coefficient of resistance is expressed by the following formula:

[0073] Resistance temperature coefficient (ppm / ℃)=(R-Ra) / Ra÷(T-Ta)×1,000,000 Here, Ra is the resistance value at the reference temperature, Ta is the reference temperature, R is the resistance value in the steady state, and T is the temperature at which the steady state is reached.

[0074] <Thermal properties> Measurement of linear expansion coefficient The linear expansion coefficient of a specific specimen was measured from among multiple specimens. The linear expansion coefficient represents the rate at which the length and volume of a specimen expand per temperature due to a rise in temperature.

[0075] [Evaluation results] The evaluation results for the resistor structure of the test specimen are explained below. <Shape of metal powder> Figure 4 shows an example of an SEM image of the granulated nichrome powder. As shown in Figure 4, the particles of the nichrome powder were almost spherical because they were not subjected to a flattening treatment. Specifically, the aspect ratio of the nichrome particles was within the range of 1.0 to 1.7.

[0076] In this way, by using nichrome powder having an aspect ratio in the range of 1.0 or more and 2.0 or less as the metal powder of the resistance material 11a, the alumina powder and nichrome powder are mixed uniformly, which makes it easier for the alumina powder to be uniformly dispersed inside the test piece.

[0077] <Structure of the specimen> Figure 5 shows SEM images of the cross section of a test piece with a 50:50 alumina powder and nichrome powder ratio, and Figure 6 shows SEM images of the cross section of a test piece with a 60:40 alumina powder and nichrome powder ratio.

[0078] 5 and 6, the black parts are alumina particles (particles of alumina powder), and the other parts are nichrome powder. The color intensity of the other parts varies depending on the crystal orientation of the nichrome.

[0079] As shown in Figures 5 and 6, the specimen has a sea-island structure consisting of islands containing insulating alumina particles and a sea made of metallic nichrome powder. It is believed that the sea-island structure remains even when the specimen is cut from any direction.

[0080] Therefore, in the specimen, a large number of nichrome particles melted and connected three-dimensionally around the unmelted alumina particles, forming a mesh-like network. That is, the metal body to which the nichrome particles are bonded is formed so as to enclose at least a part of the surface of the alumina particle.

[0081] In this way, the test specimen is composed of insulating particles and a three-dimensional mesh-like metal body surrounding the particles. This allows the alumina particles to reduce the amount of current passing through per unit area, while the three-dimensional mesh-like nichrome ensures many paths for the current to flow.

[0082] On the other hand, conventional resistance materials that use alumina as a matrix material have difficulty securing a current path unless the metal particles are flattened, and the contact area between the nichrome particles is narrowed, which tends to result in poor contact. Generally, areas where the contact between the nichrome particles is poor are prone to changes in contact due to temperature changes or the application of high voltage, which can cause fluctuations in the resistance value.

[0083] In contrast, in the resistive material 11a of this embodiment, the nichrome metal is formed into a three-dimensional mesh, so the contact area between the nichrome particles is larger than in resistive materials using alumina as a matrix material, and therefore the areas with poor contact can be reduced.In addition, the nichrome particles melt and bond together, improving adhesion and preventing dielectric breakdown due to the application of high voltage.

[0084] In the resistive material 11a, the insulating material (alumina particles) is present as a filler in a particle state without being melted. This structure makes it less susceptible to dielectric breakdown due to high voltage or high temperature. Note that if the matrix is ​​made of insulating material (alumina), the insulation is non-uniform, making it more likely to undergo dielectric breakdown at high voltage. On the other hand, in this embodiment, a metal body is formed in a three-dimensional mesh around the insulating material, which stabilizes the resistance characteristics.

[0085] Furthermore, as shown in Figure 6, even when the nichrome content in the test specimen is reduced from 50 vol% to 40 vol%, the occupancy rate of alumina particles per unit area increases, but the nichrome powder is formed to surround a large number of alumina particles in a three-dimensional mesh. Therefore, regardless of the nichrome content, the resistivity of the resistance material 11a can be increased while stabilizing the resistance characteristics. Note that even when the nichrome content is reduced to 30 vol%, a similar three-dimensional nichrome mesh structure is formed.

[0086] <Resistance characteristics / thermal characteristics> The resistance and thermal properties of the specimens are shown in Tables 1 and 2.

[0087] [Table 1]

[0088] [Table 2]

[0089] According to the results shown in Table 1, specimen T1, which contained 20 vol% nichrome, was unable to secure a current path and far exceeded the resistance required for a resistive material, exhibiting properties almost similar to that of an insulator. Furthermore, specimen T10, which contained 90 vol% nichrome, had a low resistivity almost equivalent to that of nichrome alone.

[0090] Therefore, the nichrome content is preferably 30 vol% or more and 80 vol% or less of the entire resistance material 11a. By changing the nichrome content within this range, it is possible to design the resistivity to a value between 200 μΩ·cm and 30,000 μΩ·cm, and to keep the TCR below 100 ppm, which is the allowable range from the viewpoint of ensuring current detection accuracy. To further reduce the TCR, it is preferable to design the nichrome content to a value between 35 vol% and 80 vol%.

[0091] Furthermore, according to the results shown in Table 1, it was found that as the nichrome content decreases from 40 vol%, the resistivity and TCR tend to rise sharply. The reason for this is presumably that as the three-dimensional mesh-like current paths in the test specimen become thinner and the number of current paths decreases, the effects of changes in the contact state between nichrome particles due to changes in temperature, current, etc. become more likely to appear in both the resistivity and TCR.

[0092] However, because the nichrome is formed into a three-dimensional mesh, it is easier to secure a current path compared to when alumina is used as the matrix material, and this suppresses the abrupt change in resistance characteristics that accompanies changes in the nichrome content. Therefore, even if the nichrome content is reduced, the TCR remains below 100 ppm. For the same reason, it is thought that individual differences are also suppressed.

[0093] From the above results, it was found that when the nichrome content is 30 vol% or more and 80 vol% or less of the entire resistive material 11a, the resistivity of the resistive material 11a is made larger than the resistivity of nichrome alone, while stable resistive characteristics are obtained.

[0094] In the above examples, nichrome was used as the metal body, but it is also possible to form a three-dimensional mesh using at least one alloy selected from the group consisting of copper-manganese and copper-nickel. Furthermore, the content of the alloy is preferably 30 vol% or more and 80 vol% or less from the viewpoint of ensuring a higher resistivity than the alloy alone while maintaining the function as a resistor.

[0095] Although alumina was used as the insulating particles, it is believed that similar resistance characteristics can be obtained by using at least one ceramic powder selected from the group consisting of aluminum nitride, silicon nitride, and zirconia.

[0096] In the above embodiment, only insulating alumina powder is added to conductive nichrome powder to form the resistive material 11a, but other powders may be added to improve the resistive characteristics. Even if the resistive material 11a is formed by adding other powders to the nichrome powder in addition to the alumina powder, it is possible to form a three-dimensional mesh-like metal body surrounding the particles.

[0097] According to the results shown in Table 2, the linear expansion coefficient of the test specimens was greater than that of test specimen T0, which consisted of alumina alone, and less than that of test specimen T11, which consisted of nichrome alone. As the nichrome content decreased, the linear expansion coefficient of the test specimens approached that of test specimen T0, which consisted of alumina alone.

[0098] In this way, by mixing the ceramic material used for the substrate material as insulating particles, it is possible to suppress cracks that occur at the joint between the resistor 1 and the substrate due to heat cycles. [Explanation of symbols]

[0099] 1 resistor 11 Resistance Body 11a Resistance Materials 21, 22 electrodes

Claims

1. A resistor having a rectangular plate shape and a first plane and a second plane in the thickness direction; a first electrode formed on the first plane; a second electrode formed on the second plane; a current detection multilayer resistor configured as a laminated structure of the resistor, the first electrode, and the second electrode, and mounted on a wiring pattern or a power semiconductor for current detection, the resistor has a length in the first plane and the second plane that is greater than a length in a stacking direction of the stacked structure, The resistor is made of a resistive material having a specific resistance of 200 μΩ cm or more and 300,000 μΩ cm or less, and is formed by mixing a metal body made of a conductive metal material with insulating particles made of an insulating material, and the resistor is exposed at an end surface of the current detection multilayer resistor, and the end surface of the current detection multilayer resistor is shaped so that the first electrode, the second electrode and the resistor are flush with each other. Multilayer resistor for current detection.

2. 2. The current detection multilayer resistor according to claim 1, The current detection multilayer resistor, wherein the metal element contained in the resistor is 30 vol % or more and 80 vol % or less.

3. 3. The current detection multilayer resistor according to claim 1, The metal body is a current detection multilayer resistor formed in a three-dimensional mesh between the first electrode and the second electrode.

4. 4. The current detection multilayer resistor according to claim 1, The resistor is a current detection multilayer resistor, which is a sintered body obtained by sintering metal powder for forming the metal body and the insulating particles.

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