Integrated planar curve-shaped dual-resistance current sampling element and preparation method

Abstract

The application discloses an integrated planar curve-shaped double-resistance current sampling element and a preparation method thereof. The current sampling element comprises a resistance body, an insulating layer, a plurality of electrodes and a packaging body. The resistance body comprises a sampling resistance and a reference resistance. Electrodes are arranged at both ends of the sampling resistance and the reference resistance. The preparation method fundamentally eliminates processing stress by means of over-mold injection molding technology, realizes high consistency of the two resistances at a material microscopic level, fundamentally solves a long-term matching problem, designs a specific non-linear isolation structure, maximizes effective heat conduction area and efficiency between the sampling resistance and the reference resistance, thereby establishing a faster and more uniform temperature field between the two areas, and further improving current sampling, especially real-time performance and accuracy of dynamic current sampling.

Description

Technical Field

[0001] This invention relates to the field of precision electronic components and sensor manufacturing technology, specifically to an integrated planar curved dual-resistance current sampling element and its preparation method. Background Technology

[0002] In the field of high-precision current sampling, an integrated dual-resistor structure, where the sampling resistor and reference resistor are thermally coupled but electrically isolated, is an effective solution to the temperature drift problem. Existing technologies typically employ an integrated dual-resistor structure with linear separation. While simple linear insulating dividers can achieve basic thermal coupling, under high-power pulse or rapid load changes, a slight temperature difference and thermal response hysteresis may still exist between the two regions due to limited heat conduction paths. Currently, the mainstream methods for manufacturing such components include: planar processing: forming the resistor pattern and isolation trenches on the resistor body through photolithography and etching. This method is suitable for simple linear trenches, but when manufacturing complex curved trenches, it suffers from poor etching uniformity, difficulty in controlling sidewall morphology, low material utilization, and cannot achieve three-dimensional structures. All of the above methods face bottlenecks due to inherent limitations in the process, particularly in achieving extreme consistency between the two resistor bodies and complex structural designs. Summary of the Invention

[0003] Purpose of the invention: This invention proposes an integrated planar curved dual-resistance current sampling element and its preparation method. By designing a non-linear isolation structure and preparing it through a potting and curing process, the effective heat conduction area and efficiency between the sampling resistor region and the reference resistor region are maximized, thereby establishing a faster and more uniform temperature field between the two regions.

[0004] Technical Solution: This invention proposes an integrated planar curved dual-resistance current sampling element, comprising a resistor body and an encapsulation body located around the resistor body; the resistor body includes a sampling resistor and a reference resistor, both of which are continuously bent along the same extension direction, and each bend of the sampling resistor and the reference resistor corresponds one-to-one with the same bending angle and direction; an insulating layer is provided between the sampling resistor and the reference resistor, the insulating layer is also continuously bent, one side of the insulating layer is attached to the sampling resistor, and the other side is attached to the reference resistor; the sampling resistor and the reference resistor are electrically insulated but thermally coupled; electrodes are provided at both ends of the sampling resistor and the reference resistor.

[0005] Preferably, the sampling resistor, reference resistor, and insulating layer are serpentine, sawtooth, or wavy in shape.

[0006] Preferably, the ratio of the total length of the insulating layer to the projected straight line length of the insulating layer in the horizontal direction is the thermal coupling gain coefficient, and the thermal coupling gain coefficient ranges from 1.5 to 5.0.

[0007] Preferably, the resistor body is made of manganese copper alloy-epoxy resin composite material, wherein the mass ratio of each component of the manganese copper alloy is: manganese 8%~12%, copper 83%~87%, and nickel 4%~6%.

[0008] Preferably, the insulating layer material is an insulating thermally conductive silicone grease, and the encapsulation material is an epoxy potting compound, modified silicone, or polyurethane potting compound.

[0009] Preferably, the electrode extends out of the package and contacts the outside, and the electrode material is a silver-palladium alloy.

[0010] A method for fabricating an integrated planar curved dual-resistance current sampling element includes the following steps:

[0011] S1: Provide a mold with a cavity, wherein the cavity is a continuous bent shape with the same shape as the sampling resistor and the reference resistor, and the thickness of the cavity is the sum of the thickness of the sampling resistor, the thickness of the reference resistor and the thickness of the insulating layer. A detachable isolation core is provided inside the cavity, and the shape of the isolation core is the same as the shape of the insulating layer.

[0012] S2: Prepare the resistance paste and pour the resistance paste into the cavity until it is completely filled;

[0013] S3: Simultaneously solidify the resistance paste in the cavity to form a preform with a sampling resistance region and a reference resistance region;

[0014] S4: After curing is completed and the insulating core is removed, an integrated resistor preform with partition channels is obtained;

[0015] S5: An insulating layer is formed by filling and curing the spacer within the integrated resistor preform;

[0016] S6: Demold the integrated resistor preform with an insulating layer, set electrodes at both ends of the sampling resistor and the reference resistor, and pot and solidify the integrated resistor preform to form an encapsulation body, thus obtaining the current sampling element.

[0017] Preferably, the isolation wall is serpentine, sawtooth, or wavy in shape, and the insulating layer material is insulating thermally conductive silicone grease.

[0018] Preferably, the specific steps of the resistive slurry preparation process are as follows: When using a manganese copper alloy-epoxy resin composite material, prepare 70-78 parts by weight of manganese copper alloy powder, 15-20 parts by weight of epoxy resin, 3-5 parts by weight of curing agent, 0.8-1.5 parts by weight of polymeric dispersant, and 0.2-1.0 parts by weight of defoamer; sequentially add epoxy resin, polymeric dispersant, and defoamer into a mixing tank and mix evenly; add all manganese copper alloy powder in batches and stir at 300-600 r / min for 25-40 min until the powder is fully impregnated; after stirring, add curing agent and continue stirring for 10-15 min to mix evenly; after grinding and refining and vacuum degassing, it is ready for use.

[0019] Preferably, the resistive slurry preparation process further includes: when using a silver alloy-epoxy resin composite material, preparing 70-80 parts by weight of flake silver powder, 12-18 parts by weight of submicron spherical silver powder, 10-14 parts by weight of liquid epoxy resin, 0.6-1.0 parts by weight of polymeric dispersant, 0.15-0.4 parts by weight of defoamer, 3-4 parts by weight of curing agent compatible with liquid epoxy resin, and 0.5-1.5 parts by weight of DBE solvent; wherein the median particle size range of the flake silver powder is 2-4 μm, and the median particle size range of the submicron spherical silver powder is 0.5-1.5 μm. μm; First, stir and mix epoxy resin, polymeric dispersant, defoamer, and DBE solvent evenly; first, add flake silver powder and stir at low speed for 20 min, then add submicron spherical silver powder and continue stirring for 20-30 min. Perform multi-stage gradient grinding on the stirred slurry to control the fineness of the slurry to ≤5μm; after grinding, maintain the temperature at 15℃-25℃, add curing agent and stir for 8-12 min; after vacuum degassing at -0.085~-0.095MPa for 15-20 min, it is ready for use; the temperature during the preparation of the resistance slurry is controlled at 15℃-28℃.

[0020] Beneficial effects: This invention, through the design of a non-linear isolation structure, increases the heat conduction area, thereby significantly reducing the thermal equilibrium time. The optimized heat conduction path avoids local "thermal dead zones," ensuring that the temperature measured by the reference resistor is more representative of the average temperature of the sampling resistor. This invention uses mold casting, ensuring that the sampling resistor and reference resistor originate from the same batch of slurry and are simultaneously cured in the same mold, guaranteeing absolute consistency in composition, density, and microstructure, fundamentally solving the long-term matching problem. It avoids all external force operations such as mechanical cutting, etching, and winding, resulting in uniform stress during the curing process and extremely high long-term stability of the component. Mold casting is suitable for flexible production of multi-variety, small-batch, high-performance components, reducing the manufacturing cost of complex structural components. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the mold structure in preparation method S1 of the present invention;

[0022] Figure 2 This is a schematic diagram of the component structure after the preparation method S2 of the present invention is completed;

[0023] Figure 3 This is a schematic diagram of the isolation core being removed in step S4 of the preparation method of the present invention;

[0024] Figure 4 This is a schematic diagram of the component structure after step S5 of the preparation method of the present invention;

[0025] Figure 5 This is a schematic diagram of the component structure after welding the electrodes in preparation method S6 of the present invention;

[0026] Figure 6 This is a schematic diagram of the overall structure of the integrated planar curved dual-resistance current sampling element in this invention;

[0027] Figure 7 This is a schematic diagram of the mold structure without an isolation core in the preparation method of the present invention;

[0028] Figure 8 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0029] Example 1

[0030] like Figure 6 As shown, an integrated planar curved dual-resistance current sampling element includes a resistor body, an insulating layer 1, electrodes 4, and a package 6. The resistor body includes a sampling resistor 2 and a reference resistor 3. Both the sampling resistor 2 and the reference resistor 3 are continuously bent along the same extension direction, and each bend of the sampling resistor 2 and the reference resistor 3 corresponds one-to-one with the same bending angle and direction. An insulating layer 1 is provided between the sampling resistor 2 and the reference resistor 3. One side of the insulating layer 1 is connected to the sampling resistor 2, and the other side is connected to the reference resistor 3. The ratio of the total length of the insulating layer 1 to the linear projection length of the insulating layer 1 in the horizontal direction is the thermal coupling gain coefficient, which ranges from 1.5 to 5.0. The shapes of the sampling resistor 2, the reference resistor 3, and the insulating layer 1 are serpentine, sawtooth, or wavy. This substantially increases the contact boundary length between the sampling resistor 2 and the reference resistor 3 without changing the physical distance between them. The time required for the sampling resistor 2 and the reference resistor 3 to reach temperature equilibrium under a step-high current load is significantly shortened. To maximize the effective thermal conductivity area and efficiency between the sampling resistor and the reference resistor, a faster and more uniform temperature field is established between them. The resistor body material is a manganese-copper alloy-epoxy resin composite material, where the mass ratio of the manganese-copper alloy components is: manganese 8%~12%, copper 83%~87%, and nickel 4%~6%. The insulating layer 1 material is insulating thermally conductive silicone grease.

[0031] Both sampling resistor 2 and reference resistor 3 have electrodes 4 at both ends. Electrodes 4 are made from silver-palladium conductive paste and are fabricated using any one of the following processes: screen printing sintering, chip bonding, or metal plating deposition. Electrodes 4 are tightly attached to the ends of the resistor body, forming a strong ohmic contact. Electrodes 4 at the sampling resistor 2 are used to connect the measured current, converting the current signal into a voltage sampling signal. Electrodes 4 at the reference resistor 3 are used to acquire a reference voltage signal, achieving temperature drift compensation and signal calibration. The electrodes 4 at the sampling resistor 2 and reference resistor 3 have identical structure, dimensions, materials, and fabrication processes. This identical parameter configuration eliminates sampling errors caused by differences in electrode resistance and contact resistance, ensuring the symmetry and consistency of the dual-resistor signal acquisition, and further improving current sampling accuracy and long-term stability.

[0032] The package 6 encapsulates the resistor body, insulation layer 1, and the outer side of electrode 4. Electrode 4 extends out of the package 6 to contact the outside, facilitating subsequent external measurements. The package 6 is made of epoxy potting compound, modified silicone, or polyurethane potting compound. An integrated potting and curing process is used to form a unified protective shell after potting. The functions and effects of the package are: firstly, to achieve overall electrical insulation, preventing the intrusion of external dust, moisture, and oil, and avoiding component leakage and short circuits; secondly, to provide excellent mechanical protection, buffering damage from vibration and impact, and eliminating additional stress during use; thirdly, to assist in overall heat dissipation, maintaining uniform overall component temperature; simultaneously, the package is tightly bonded to the internal structures, effectively delaying the aging of the resistor body and electrodes, significantly extending the component's lifespan, and adapting to long-term operation under complex conditions such as high power and dynamic current.

[0033] Example 2

[0034] A method for fabricating an integrated planar curved dual-resistance current sampling element includes the following steps:

[0035] S1: Provide a mold 8 with a cavity 8-1. The cavity 8-1 is a continuous bent shape with the same shape as the sampling resistor 2 and the reference resistor 3. The thickness of the cavity 8-1 is the sum of the thickness of the sampling resistor 2, the thickness of the reference resistor 3 and the thickness of the insulating layer 1. A detachable isolation core 8-2 is provided inside the cavity 8-1. The shape of the isolation core 8-2 is the same as the shape of the insulating layer 1.

[0036] S2: Prepare the resistance paste and pour the resistance paste into the cavity 8-1 until it is completely filled;

[0037] The preparation process of the resistance paste is as follows:

[0038] When using a manganese-copper alloy-epoxy resin composite material, prepare the following components by weight: 70-78 parts manganese-copper alloy powder, 15-20 parts epoxy resin, 3-5 parts curing agent, 0.8-1.5 parts polymeric dispersant, and 0.2-1.0 parts defoamer. The average particle size of the manganese-copper alloy powder is 5-15 μm, and the mass ratio of each component is: manganese 8%-12%, copper 83%-87%, and nickel 4%-6%. The epoxy resin should be electronic-grade bisphenol A type epoxy resin (such as E-44, E-51, or a combination thereof), the curing agent should be a polyetheramine curing agent (such as D2000, D400, or a combination thereof), the polymeric dispersant should be a copolymer dispersant containing acidic groups (such as BYK-163), and the defoamer should be a modified polysiloxane defoamer (such as BYK-065).

[0039] In preparation, epoxy resin, polymeric dispersant, and defoamer are first added to a mixing tank and mixed evenly. Then, all manganese-copper alloy powder is added in batches and stirred at 300–600 rpm for 25–40 minutes to fully impregnate and break up any agglomerates, ensuring the metal powder is fully impregnated and evenly dispersed within the epoxy resin matrix. After stirring, the curing agent is added and stirred at 200–400 rpm for 10–15 minutes to ensure uniform mixing with the resin system. The mixture can be further refined by grinding and vacuum degassing as needed. Vacuum degassing involves placing the mixed slurry in a vacuum degassing device and degassing for 15–30 minutes under a vacuum of ≤-0.095 MPa until no obvious bubbles escape from the slurry surface, resulting in a uniform, highly fluid resistive slurry. The manganese-copper alloy-epoxy resin slurry exhibits excellent chemical stability, requires no low-temperature control, and can be prepared entirely at room temperature.

[0040] When using a silver alloy-epoxy resin composite material, prepare 70-80 parts by weight of flake silver powder, 12-18 parts by weight of submicron spherical silver powder, 10-14 parts by weight of liquid epoxy resin, 0.6-1.0 parts by weight of polymeric dispersant, 0.15-0.4 parts by weight of defoamer, 3-4 parts by weight of curing agent, and 0.5-1.5 parts by weight of DBE solvent. The median particle size range of the flake silver powder is 2-4 μm, and the median particle size range of the submicron spherical silver powder is 0.5-1.5 μm. The defoamer is a polyether-modified silicone defoamer, and the curing agent is a polyether amine curing agent, such as D230 or D400, or a modified aliphatic amine or alicyclic amine curing agent. It is suitable for low-temperature mixing processes and can effectively prevent silver powder oxidation and premature gelation of the slurry.

[0041] The premixed carrier is prepared by first stirring and mixing epoxy resin, dispersant, defoamer, and DBE solvent until uniform;

[0042] Powder batch feeding: First, add flake silver powder and stir at low speed for 20 minutes, then add submicron spherical silver powder and continue stirring for 20-30 minutes. The bulk density is increased by relying on the mutual filling of the compound silver powder.

[0043] Grinding and refining: Perform multi-stage gradient grinding to control the fineness of the slurry to ≤5μm, so that the silver sheets can fully overlap and reduce the contact resistance of the particles;

[0044] Hardener mixing: After grinding, keep the temperature at 15℃~25℃, add hardener and stir for 8~12 minutes to avoid heat oxidation of silver powder;

[0045] Vacuum degassing: -0.085~-0.095MPa vacuum degassing for 15~20min to completely eliminate internal microbubbles;

[0046] The preparation process is kept at a temperature of 15℃~28℃ to avoid frictional heat generated during stirring and grinding, which could lead to silver powder oxidation and premature gelation of the slurry.

[0047] The prepared resistance slurry is slowly poured into the cavity 8-1 of the mold 8, ensuring a continuous flow of slurry without air bubbles being incorporated, until the cavity 8-1 is completely filled with the resistance slurry and the slurry surface is flush with the upper edge of the mold. After pouring, the mold 8 is placed on a flat surface and left to stand for 5-15 minutes to allow the residual stress inside the slurry to release naturally, in preparation for the subsequent curing step.

[0048] S3: Simultaneously cure the resistive paste inside the cavities 8-1 on both sides of the isolation core 8-2 to form a preform with sampling resistance 2 and reference resistance 3.

[0049] S4: After curing is completed and the insulating core is removed, an integrated resistor preform with partition channel 7 is obtained;

[0050] S5: An insulating layer 1 is formed by filling and curing the partition channel 7 of the integrated resistor blank. The insulating layer 1 is made of insulating thermally conductive silicone grease, which realizes the electrical isolation between the sampling resistor 2 and the reference resistor 3, while maintaining the thermal coupling state.

[0051] S6: Demold the integrated resistor preform with insulating layer 1, and set electrodes at both ends of sampling resistor 2 and reference resistor 3. Use laser trimming process to precisely fine-tune the resistance values ​​of sampling resistor 2 and reference resistor 3. After trimming, perform electrical performance testing on the semi-finished product and remove unqualified products. Then, encapsulate and cure the qualified products to form package 6. After encapsulation, protect the surface of the component. Finally, perform finished product testing and screening to obtain the current sampling component.

[0052] The electrode setup can be achieved using any one of the following methods: screen printing sintering, chip welding, or metal plating deposition.

[0053] Laser resistance fine-tuning employs a laser trimming process: an infrared laser beam selectively cuts the resistive element, and the resistance changes of sampling resistor 2 and reference resistor 3 are measured in real time. The laser automatically stops cutting when the resistance reaches the preset target range. The laser cutting direction is parallel to the current direction, alternately cutting straight edges on the non-electrode opposite sides of the resistive conductor to avoid creating protrusions or sharp points, ensuring a uniform and smooth current flow within the resistive body. After laser trimming, the resistance accuracy of sampling resistor 2 and reference resistor 3 is controlled within ±0.1%, ensuring the matching accuracy of the two resistors.

[0054] The electrical performance testing of semi-finished products uses automated testing equipment to conduct preliminary electrical performance tests on the laser-adjusted resistor preforms, including the resistance accuracy of sampling resistor 2 and reference resistor 3 and the matching degree of the two resistors. Semi-finished products that still do not meet the standards after adjustment are rejected to prevent defective products from flowing into the subsequent packaging process.

[0055] The encapsulation process employs an integrated potting and curing technique: the tested and qualified semi-finished resistor preform is placed in a packaging mold, and encapsulation is performed using epoxy potting compound, modified silicone, or polyurethane potting compound as the encapsulation material. After potting, it is cured by heat to form an integrated encapsulation body 6, allowing the electrodes 4 to protrude from the encapsulation body 6 and contact the outside environment. The encapsulation body 6 covers the resistor body, the insulating layer 1, and the outer periphery of the inner part of the electrodes, achieving overall electrical insulation and mechanical protection, and assisting in overall heat dissipation.

[0056] Surface protection employs a conformal coating process: the surface of the encapsulated resistor element is cleaned to remove oil and impurities, and then conformal coating is applied using spraying, brushing, or dipping techniques to form a dense, transparent protective film. The conformal coating is selected from acrylic resins, polyurethanes, epoxy resins, or silicones, with acrylic resins or silicone conformal coatings being preferred. The coating thickness is controlled between 25 and 75 micrometers, providing moisture resistance, salt spray resistance, corrosion resistance, dust resistance, shock resistance, and insulation properties, without affecting the component's heat dissipation performance.

[0057] The finished product testing and screening process utilizes automated testing equipment to perform full-parameter inspections on the packaged and surface-protected current sampling components. This includes checking the resistance accuracy, temperature coefficient, and dual-resistance matching degree of sampling resistor 2 and reference resistor 3, as well as the overall insulation resistance and withstand voltage of the components. Components that do not meet the technical specifications are rejected to ensure the consistency and reliability of the products leaving the factory. After testing and screening, qualified components are labeled and packaged, completing the finished product manufacturing process.

[0058] The curing methods in S3 and S5 are heating, ultraviolet light irradiation or chemical catalysis. The electrode setup in S6 includes any one of screen printing sintering, patch welding or metal plating deposition. The electrode material is silver-palladium conductive paste.

[0059] like Figures 1 to 7As shown, the integrated dual-resistance current sensing element manufactured above uses 75 parts by weight of manganese-copper alloy powder with an average particle size of 5μm, a manganese content of 10%, a copper content of 85%, and a nickel content of 5%, 18 parts by weight of electronic-grade bisphenol A special epoxy resin E-44, 1.2 parts by weight of BYK-163 polymeric dispersant, and 0.8 parts by weight of BYK-065 defoamer. The mixture is first stirred at 300-600 r / min for 20-40 minutes to impregnate the metal powder, and then 4 parts by weight of polyetheramine D2000 curing agent are added. The mixture is stirred at 200-400 r / min for 10-20 minutes to mix evenly. After vacuum degassing (vacuum degree ≤ -0.095MPa, time 15-30 minutes), a uniformly mixed resistor body slurry is formed.

[0060] The insulating layer uses insulating thermally conductive silicone grease, and the electrode 4 uses silver-palladium conductive paste. The silver-palladium conductive paste is applied to both ends of the sampling resistor 2 and the reference resistor 3 via screen printing using a screen printing process. Then, it is sintered at 180–260°C for 10–30 minutes to ensure a strong ohmic contact between the electrode 4 and the resistor body. The encapsulation body 6 is made of epoxy potting compound and is formed using an integral potting and curing process. It covers the resistor body, the insulating layer 1, and the inner portion of the electrode 4, with one end of the electrode 4 extending out of the encapsulation body 6 to contact the outside.

Claims

1. An integrated planar curved dual-resistance current sampling element, characterized in that, The resistor body includes a resistor body and a package (6) located around the resistor body. The resistor body includes a sampling resistor (2) and a reference resistor (3). The sampling resistor (2) and the reference resistor (3) are both continuously bent along the same extension direction. Each bend of the sampling resistor (2) and the reference resistor (3) corresponds to one another and the bending angle and bending direction are the same. An insulating layer (1) is provided between the sampling resistor (2) and the reference resistor (3). The insulating layer (1) is also continuously bent. One side of the insulating layer (1) is attached to the sampling resistor (2) and the other side is attached to the reference resistor (3). The sampling resistor (2) and the reference resistor (3) are electrically insulated but thermally coupled. Electrodes (4) are provided at both ends of the sampling resistor (2) and the reference resistor (3).

2. The integrated planar curved dual-resistance current sampling element according to claim 1, characterized in that, The sampling resistor (2), reference resistor (3) and insulating layer (1) are serpentine, sawtooth or wavy in shape.

3. The integrated planar curved dual-resistance current sampling element according to claim 1, characterized in that, The ratio of the total length of the insulating layer (7) to the projected straight line length of the insulating layer (7) in the horizontal direction is the thermal coupling gain coefficient, which ranges from 1.5 to 5.

0.

4. The integrated planar curved dual-resistance current sampling element according to claim 1, characterized in that... The resistor body is made of manganese copper alloy-epoxy resin composite material or silver alloy-epoxy resin composite material. The mass ratio of each component of the manganese copper alloy in the manganese copper alloy-epoxy resin composite material is: manganese 8%~12%, copper 83%~87%, and nickel 4%~6%.

5. The integrated planar curved dual-resistance current sampling element according to claim 1, characterized in that, The insulating layer (1) is made of insulating thermally conductive silicone grease, and the encapsulation body (6) is made of epoxy potting compound, modified silicone or polyurethane potting compound.

6. The integrated planar curved dual-resistance current sampling element according to claim 1, characterized in that, The electrode (4) extends out of the encapsulation body (6) and comes into contact with the outside world. The material of the electrode (4) is a silver-palladium alloy.

7. A method for fabricating an integrated planar curved dual-resistance current sampling element according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Provide a mold (8) with a cavity (8-1), the cavity (8-1) being a continuous bent shape with the same shape as the sampling resistor (2) and the reference resistor (3), and the thickness of the cavity (8-1) being the sum of the thickness of the sampling resistor (2), the thickness of the reference resistor (3) and the thickness of the insulating layer (1), and a detachable isolation core (8-2) is provided inside the cavity (8-1), the shape of the isolation core (8-2) being the same as the shape of the insulating layer (1); S2: Prepare the resistance paste and pour the resistance paste into the cavity (8-1) until it is completely filled; S3: Simultaneously solidify the resistive slurry in the cavity (8-1) to form a preform with a sampling resistance region (2) and a reference resistance region (3); S4: After curing is completed and the isolation core is removed, an integrated resistor preform with a partition channel (7) is obtained; S5: Fill and cure the partition channel (7) of the integrated resistor preform to form an insulating layer (1); S6: Demold the integrated resistor preform with insulating layer (1), and set electrodes (4) at both ends of sampling resistor (2) and reference resistor (3), and pot and solidify the integrated resistor preform to form a package (6) to obtain the current sampling element.

8. The preparation method according to claim 7, characterized in that, The isolation wall (8-2) is serpentine, sawtooth or wavy in shape, and the insulating layer (1) is made of insulating thermally conductive silicone grease.

9. The preparation method according to claim 7, characterized in that, The specific steps of the resistive slurry preparation process are as follows: When using a manganese-copper alloy-epoxy resin composite material, prepare 70-78 parts by weight of manganese-copper alloy powder, 15-20 parts by weight of epoxy resin, 3-5 parts by weight of curing agent, 0.8-1.5 parts by weight of polymeric dispersant, and 0.2-1.0 parts by weight of defoamer; sequentially add epoxy resin, polymeric dispersant, and defoamer into a mixing tank and mix evenly; add all manganese-copper alloy powder in batches and stir at 300-600 r / min for 25-40 min until the powder is fully impregnated; after stirring, add curing agent and continue stirring for 10-15 min to mix evenly; after grinding and refining and vacuum degassing, it is ready for use.

10. The preparation method according to claim 9, characterized in that, The preparation process of the resistive slurry further includes: when using a silver alloy-epoxy resin composite material, preparing 70-80 parts by weight of flake silver powder, 12-18 parts by weight of submicron spherical silver powder, 10-14 parts by weight of liquid epoxy resin, 0.6-1.0 parts by weight of polymeric dispersant, 0.15-0.4 parts by weight of defoamer, 3-4 parts by weight of curing agent compatible with liquid epoxy resin, and 0.5-1.5 parts by weight of DBE solvent; wherein the median particle size range of the flake silver powder is 2-4 μm, and the median particle size range of the submicron spherical silver powder is 0.5-1.5 μm. First, stir and mix the epoxy resin, polymeric dispersant, defoamer, and DBE solvent evenly. Then, add flake silver powder and stir at low speed for 20 minutes, followed by adding submicron spherical silver powder and continuing to stir for 20-30 minutes. Perform multi-stage gradient grinding on the stirred slurry to control the fineness of the slurry to ≤5μm. After grinding, maintain the temperature at 15℃-25℃, add the curing agent and stir for 8-12 minutes. After vacuum degassing at -0.085~-0.095MPa for 15-20 minutes, it is ready for use. The temperature during the preparation of the resistive slurry is controlled at 15℃-28℃.

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