Microresistive element with conductive structure of different materials and measurement notch

Abstract

To provide a microresistive element with a heterogeneous conductive structure and a measurement notch for power modules that handle high current and high frequency measurements, thereby improving measurement accuracy and system stability. [Solution] The alloy body 10 has a first end 11 and a second end 12, with a first conductive terminal 21 and a third conductive terminal 23 provided on the first end 11, and a second conductive terminal 22 and a fourth conductive terminal 24 provided on the second end 12. The first conductive terminal 21, the third conductive terminal 23, the second conductive terminal 22, and the fourth conductive terminal 24 are joined to the alloy body 10 and configured as a conductive structure of different materials. Lateral notches 30 are cut in between the first conductive terminal 21 and the third conductive terminal 23 and between the second conductive terminal 22 and the fourth conductive terminal 24, and the lateral notches 30 extend to the middle area of ​​the alloy body 10, forming a separation area for current input and voltage measurement.

Description

TECHNICAL FIELD

[0001] The present invention relates to a micro-resistance element, in particular to a micro-resistance element having a dissimilar material conductive structure and a measurement notch, which improves the accuracy and stability of resistance value measurement by arranging a specific notch at the boundary of dissimilar materials, reduces the interference of temperature coefficient of resistance (TCR) and contact resistance on measurement results, and is suitable for high-precision current sensing and power control elements. BACKGROUND ART

[0002] Most conventional micro-resistance elements adopt a metal plate-like structure, usually using an alloy material as the main conductive body, with conductive terminals for welding to a circuit board disposed at both ends thereof. The conductive terminals are formed by welding pure copper blocks, or by electroplating copper layers on both ends of the alloy body. However, the pure copper blocks require separate assembly, which increases complexity. In addition, the electroplated copper layer may have non-uniform electroplating thickness, or due to changes in the mixing ratio of the plating solution and differences in processing conditions, the conductive properties become inconsistent, causing fluctuations in the total resistance value of the element, and the error proportion becomes even more obvious especially for elements with a nominal value of less than 1 mΩ.

[0003] Besides, the temperature coefficient of resistance (TCR) of copper material is much higher than that of common alloy materials, so the resistance value is prone to change due to thermal effect during operation, which affects the accuracy and stability. For this reason, a four-terminal micro-resistance element 100 as usually shown in Figure 1 is introduced to separate the current and voltage contacts in an attempt to reduce the error caused by contact resistance. However, the voltage detection point of this type of element is mostly located at the boundary between the copper terminal and the alloy body, and the actual measurement result is still interfered by the composite material, so that the electrical behavior of the alloy body cannot be accurately reflected. The detailed measurement results are as shown in Figure 2.

[0004] Furthermore, as described in Patent Document 1, a TCR calibration slot may be formed between the main terminal of the conductive band and the voltage sensing terminal, and the TCR value observed at the voltage sensing terminal may be compensated by adjusting the depth of the calibration slot. This device primarily adjusts the TCR compensation effect through the depth of the calibration slot, with its measurement end formed within a conductive band structure. However, the arrangement of lateral notches between the conductive terminals of different materials and the alloy body, as well as the structure of the area that separates current input and voltage measurement, which is cut from an intermediate position between the two conductive terminals on the same side and extends to the middle area of ​​the alloy body.

[0005] Furthermore, to meet the needs of high-current applications such as electric vehicles, servers, and AI computing systems, it is common practice to use multiple low-resistance elements in parallel. However, while using multiple elements in parallel improves the total current capacity and reduces the equivalent resistance, factors such as welding consistency, contact pressure, and heat dissipation inconsistencies make it difficult to control actual application errors, and it also increases the number of elements and manufacturing costs. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] People's Republic of China Patent No. CN102696079B Specification [Overview of the project] [Problems that the invention aims to solve]

[0007] Conventional microresistors are often limited by problems such as non-uniform conductivity, temperature coefficient differences, and measurement errors that occur at the boundaries of dissimilar materials when measuring low resistance currents. As a result, there are technical problems in terms of measurement accuracy for low resistance values, temperature stability, and control of interference between dissimilar materials.

[0008] The objective of this invention is to provide a microresistivity element with a heterogeneous conductive structure and a measuring notch that improves measurement accuracy and system stability and is applicable to power modules that handle high current and high frequency measurements. [Means for solving the problem]

[0009] This invention relates to a microresistivity element having a conductive structure of different materials and a measuring notch, and includes an alloy body, the alloy body having a first end and a second end provided opposite to each other, a first conductive terminal and a third conductive terminal provided at the first end of the alloy body and made of copper, a second conductive terminal and a fourth conductive terminal provided at the second end of the alloy body and made of copper, the first conductive terminal, the third conductive terminal and the second conductive terminal and the fourth conductive terminal are each joined to the alloy body and configured as a conductive structure of different materials, further, a lateral notch is cut between the first conductive terminal and the third conductive terminal, and a lateral notch is cut between the second conductive terminal and the fourth conductive terminal, the lateral notch extends to the middle area of ​​the alloy body to form a separation area for current input and voltage measurement, and improves the accuracy of resistance measurement.

[0010] Vertical slits are provided on both sides of the alloy body near the first and second conductive terminals. These vertical slits are perpendicular to the horizontal notches, and by cutting and stretching a portion of the thickness of the alloy body, the measurement area is further defined, improving the accuracy of resistance measurement. [Effects of the Invention]

[0011] This invention can achieve the following effects.

[0012] Firstly, the accuracy of the measured voltage will be improved. By providing a lateral notch within the alloy body, the voltage measurement point will be moved away from the boundary between dissimilar materials (copper / alloy), reducing measurement errors due to fluctuations in contact resistance and improving stability and repeatability at low resistance values.

[0013] Secondly, the influence of the dissimilar material transition area is reduced. By employing an alloy body with conductive terminals (plated copper layer or copper insert) on both sides and designing a lateral notch extending from the copper area to the middle section of the alloy, the main conductive structure and the measurement structure are effectively isolated, which helps stabilize the conduction behavior.

[0014] Thirdly, the consistency of the current distribution in the reinforced measurement area is enhanced. Lateral notches restrict the area through which the main current flows, further concentrating the current flowing through the measurement point on the alloy body, reducing the effects of leakage or bypass, and helping to precisely measure minute voltage differences.

[0015] Fourth, it offers a simplified structure and ease of processing. Notches can be formed by machining or etching, and it is manufactured by combining standard metal sheet materials with an electroplating process, resulting in a relatively simple manufacturing process and suitability for mass production.

[0016] Fifth, it can be further optimized according to needs. By providing a separate vertical slit structure in the middle of the main body, the degree of isolation of the measured current is further increased, reducing interference from parasitic paths and helping to meet the needs of specific applications requiring high-resolution resistance detection. [Brief explanation of the drawing]

[0017] [Figure 1] This is a cross-sectional view of a conventional microresistor. [Figure 2] This figure shows the relationship between temperature, resistance, and TCR for a conventional microresistivity element. [Figure 3] This is a cross-sectional view of a microresistivity element showing a first embodiment of the present invention. [Figure 4] This figure shows the relationship between resistance temperature, resistance value, and TCR according to the first embodiment of the present invention. [Figure 5] This is a cross-sectional view of a microresistivity element showing a second embodiment of the present invention. [Figure 6] This figure shows the relationship between resistance temperature, resistance value, and TCR according to the second embodiment of the present invention. [Figure 7]It is a diagram showing the relationship among temperature, resistance value, and TCR obtained at an ultra-low resistance value. [Mode for Carrying Out the Invention]

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0019] (First Embodiment) As shown in Figure 3, in the first embodiment of the present invention, the micro-resistance element includes an alloy body 10, and has a first end 11 and a second end 12 disposed opposite to each other. The alloy body 10 is made of a precision resistance alloy material, for example, a nickel-chromium based alloy, a manganese-copper alloy, or other resistance value material having a stable thermal coefficient, and serves as the main measurement area. The alloy body 10 has two opposite ends, each of which is provided with a pair of conductive terminals, specifically, a first conductive terminal 21 and a third conductive terminal 23 disposed on the side of the first end 11, and a second conductive terminal 22 and a fourth conductive terminal 24 disposed on the side of the second end 12. The first conductive terminal 21, the second conductive terminal 22, the third conductive terminal 23, and the fourth conductive terminal 24 are respectively extended from both ends of the alloy body 10 into its inner area and fitted, so as to enhance the electrical contact stability between these conductive terminals 21, 22, 23, 24 and the alloy body 10. The first conductive terminal 21, the second conductive terminal 22, the third conductive terminal 23, and the fourth conductive terminal 24 are made of a metal material with excellent conductivity (e.g., copper), and are fixed to both ends of the alloy body 10 by electroplating, sintering or mechanical pressure welding, forming a current path with stable and low contact resistance for the entire element.

[0020] Lateral notches 30 are provided at each of the first conductive terminal 21, the third conductive terminal 23, the second conductive terminal 22, and the fourth conductive terminal 24. The lateral notches 30 are cut from their respective pre-installed positions to intermediate positions between the first conductive terminal 21 and the third conductive terminal 23, and between the second conductive terminal 22 and the fourth conductive terminal 24, and extend beyond the first conductive terminal 21, the third conductive terminal 23, and the second conductive terminal 22 and the fourth conductive terminal 24 toward the middle area of ​​the alloy body 10. The initial end of the lateral notch 30 is located at the boundary between the first conductive terminal 21, the third conductive terminal 23, the second conductive terminal 22, the fourth conductive terminal 24 and the alloy body 10, and penetrates at least a portion of the alloy body 10. These features create a measurement area with a clear boundary within the element structure, effectively separating current interference between the conductive terminal and the measurement area, improving the accuracy of resistance measurement, and avoiding measurement bias due to terminal resistance variation or non-uniform contact.

[0021] Figure 4 shows the TCR analysis diagram for alloy body 10, which was tested based on a manganese copper tin alloy resistance material with a temperature coefficient (TCR ± 10 ppm / °C). Figure 4 shows the test results using the microresistor element shown in Figure 3. Even when the temperature rose from 25°C to 130°C, the change in resistance value was less than ±0.2%, and the change in TCR value was less than ±20 ppm°C, demonstrating stability.

[0022] (Second embodiment) Figures 5 and 6 show a second embodiment of the present invention. As shown in Figure 5, in this embodiment, in addition to the lateral notch 30 provided in the alloy body 10, vertical slits 40 are provided near the first conductive terminal 21 and near the second conductive terminal 22 of the alloy body 10. The two vertical slits 40 are located on the extended area of ​​the horizontal notch 30, and the vertical slits 40 are perpendicular to the horizontal notch 30 and cut and extend a portion of the thickness of the alloy body 10. By making the horizontal and vertical cut sections intersect in the middle area of ​​the alloy body 10, the working area for resistance measurement is further clearly partitioned and concentrated. The introduction of the vertical slits 40 further suppresses the lateral diffusion effect in the current distribution of the alloy body 10, helping to improve the accuracy of the analysis of minute resistance values, reducing interference to resistance measurement results due to edge effects, and optimizing the stability and accuracy in the actual application of the optimized element.

[0023] Figure 6 is a TCR analysis diagram based on alloy body 10 made from a manganese copper-tin alloy resistance material with a temperature coefficient (TCR ± 10 ppm / °C). Figure 6 shows the results of testing with the microresistivity element shown in Figure 5. Even when the temperature rose from 25°C to 130°C, the change in resistance value was less than ±0.2%, and the change in TCR value was less than ±20 ppm°C. The second embodiment showed even more stable results compared to the first embodiment.

[0024] Figure 7 shows the results obtained at ultra-low resistance values, demonstrating that the resistance values ​​are stable and the TCR values ​​do not vary significantly.

[0025] As a specific effect of this invention, the microresistivity element can be used as an electrical connection interface for introducing and deriving current by contacting the first conductive terminal 21 and the second conductive terminal 22 via external measuring equipment, and as a voltage difference measurement connection interface at the third conductive terminal 23 and the fourth conductive terminal 24. By applying current, a current path is formed in the element, creating a main resistance reaction area in the middle area of ​​the alloy body 10. This reaction area is defined by a lateral notch 30 (and a vertical slit 40, if present), allowing a measuring probe to be brought into contact at a specific position to obtain a stable voltage drop signal. This helps eliminate errors caused by terminal contact resistance and non-uniformity of the contact surface, improving the practicality and repeatability of precise current monitoring of microresistive elements, power module protection, or temperature control systems.

[0026] The above describes embodiments of the present invention, and any modifications that do not depart from the claims are included within the scope of the rights of the present invention. [Explanation of Symbols]

[0027] 10 Alloy body 11 First end 12 Second end 21 First conductive terminal 22 Second conductive terminal 23 Third conductive terminal 24 Fourth conductive terminal 30 horizontal notches 40 vertical slits

Claims

1. A microresistive element having a conductive structure of different materials and a measuring notch, comprising an alloy body, The alloy body has a first end and a second end that are provided opposite to each other. The first conductive terminal and the third conductive terminal are provided at the first end of the alloy body, and are made of copper. The second conductive terminal and the fourth conductive terminal are provided at the second end of the alloy body, and are made of copper. The first conductive terminal, the third conductive terminal, the second conductive terminal, and the fourth conductive terminal are each joined to the alloy body and configured as a conductive structure of different materials. Furthermore, a lateral notch is cut between the first conductive terminal and the third conductive terminal, and a lateral notch is cut between the second conductive terminal and the fourth conductive terminal, and the lateral notch extends to the middle area of ​​the alloy body to form a separation area for current input and voltage measurement, thereby improving the accuracy of resistance measurement. This is a microresistivity element having a conductive structure of different materials and measurement notches.

2. The first to fourth conductive terminals are each extended from both ends of the alloy body into its internal area and fitted, thereby enhancing the electrical contact stability between these conductive terminals and the alloy body, as described in claim 1, for a microresistivity element having a conductive structure of different materials and a measuring notch.

3. A microresistivity element having a conductive structure of different materials and a measuring notch, as described in claim 1, characterized in that vertical slits are provided near the first and second conductive terminals on both sides of the alloy body, the vertical slits are perpendicular to the horizontal notch, and the measurement area is further defined by cutting and stretching a portion of the thickness of the alloy body, thereby improving the accuracy of resistance measurement.

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