An integrated dual-resistance current sensing element and a method of manufacturing the same

Abstract

The application discloses an integrated double-resistance current sensing element and a manufacturing method thereof, which comprises a body, a filling layer, a plurality of electrodes and a package body; a channel is etched at the center of the resistance body to separate the resistance body into a sampling resistance area and a reference resistance area; the filling layer is arranged in the channel and contacts the sampling resistance area and the reference resistance area on the two sides; and the sampling resistance area and the reference resistance area are both provided with electrodes. The sensing element prepared by the application is divided into two by a unique physical structure design, and the two are connected through an insulating high-thermal-conductivity medium in the middle, so that the most extreme thermal coupling is realized, and thus the resistance value of the reference resistance can accurately reflect the real temperature of the sampling resistance in real time, and the long-term precision and stability of current sampling are fundamentally improved.

Description

Technical Field

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

[0002] In fields such as power electronics and battery management, which require accurate sampling of large currents, a common approach is to use a sampling resistor in conjunction with an amplifier. However, under high current, the sampling resistor heats up due to self-heating, causing its resistance to change with temperature (temperature drift), leading to measurement errors. Existing technologies typically address this by: using low-temperature-drift resistors, such as manganin resistors, but these are costly and still exhibit some temperature drift; external temperature sensor compensation, where a thermistor (such as an NTC) or temperature sensor chip is installed near the sampling resistor to estimate the resistance temperature rise and compensate by measuring the ambient temperature. This method suffers from problems such as temperature hysteresis and positional deviation, resulting in limited compensation accuracy; and software algorithm compensation, which establishes complex temperature drift models, but these models are susceptible to individual differences and aging, leading to poor long-term stability. None of these methods fundamentally solve the problem of direct, real-time measurement of the sampling resistor's body temperature, making it difficult to guarantee the accuracy and reliability of current sampling under long-term operation, dynamic loads, or high-temperature environments. Summary of the Invention

[0003] Purpose of the invention: This invention proposes an integrated dual-resistance current sensing element and its manufacturing method, which divides the resistor body into two parts and connects them in the middle with thermally conductive insulating adhesive to achieve insulation and thermal coupling, thereby improving the long-term accuracy and stability of current sampling.

[0004] Technical Solution: The present invention proposes an integrated dual-resistance current sensing element, comprising a resistor body and an encapsulation disposed around the resistor body; the resistor body is etched with channels to divide the resistor body into a sampling resistor region and a reference resistor region, and a filling layer is disposed in the channels, one end of the filling layer being connected to the sampling resistor region and the other end being connected to the reference resistor region, the sampling resistor region and the reference resistor region being electrically insulated but thermally coupled; a first electrode is disposed at both ends of the sampling resistor region, and a second electrode is disposed at both ends of the reference resistor region.

[0005] Preferably, the width of the channel is 50μm to 500μm.

[0006] Preferably, the filler layer material is a thermally conductive insulating adhesive.

[0007] Preferably, the resistor body material is a manganese copper alloy, a nickel-chromium alloy, or an Evan alloy; the resistor body shape is a thin film or a foil.

[0008] Preferably, a plurality of first electrodes are fixed at both ends of the sampling resistor region, and the first electrodes pass through the package and contact the outside; the second electrodes are fixed at both ends of the reference resistor region, and one end of the second electrode extends out of the package and contacts the outside. The first electrodes are thick copper electrodes plated with nickel and then tin, and the second electrodes are gold-plated electrodes. The size of the first electrodes is larger than the size of the second electrodes.

[0009] Preferably, the package thickness on the side of the sampling resistor region away from the fill layer is less than the package thickness on the side of the reference resistor region away from the fill layer.

[0010] Preferably, the encapsulation body is an insulating material, preferably epoxy resin or silicone.

[0011] A method for manufacturing an integrated dual-resistance current sensing element includes the following steps:

[0012] Step 1: Provide a uniformly doped resistor body;

[0013] Step 2: Etch a channel on the resistor body from Step 1 to divide the resistor body into a sampling resistor area and a reference resistor area;

[0014] Step 3: Prepare a filling layer in the channel of Step 2, with the two sides of the filling layer respectively attached to the sampling resistor region and the reference resistor region;

[0015] Step 4: Form the first electrode at both ends of the sampling resistor region in Step 3, and form the second electrode at both ends of the reference resistor region;

[0016] Step 5: Prepare a package on the surface of the filling layer, the sampling resistor region and the reference resistor region, with the first electrode and the second electrode extending out of the package to obtain a rough current sensing element;

[0017] Step 6: Perform high-temperature aging and power load screening tests on the crude current sensing element to eliminate elements with inconsistent drift, and obtain the final current sensing element.

[0018] Preferably, the first electrode and the second electrode are fixed by electroplating or welding; the first electrode is a thick copper electrode plated with nickel and then tin, the second electrode is a gold-plated electrode, and the size of the first electrode is larger than the size of the second electrode.

[0019] Preferably, the channel is formed by laser etching, mechanical cutting or chemical etching, the channel width is 50μm to 500μm, and the filling layer material is thermally conductive insulating adhesive.

[0020] Beneficial Effects: The current sensing element prepared by this invention exhibits zero temperature sensing hysteresis. The reference resistor region and the sampling resistor region are integral and at the same temperature, enabling instantaneous reflection of any temperature changes in the sampling resistor due to self-heating or environmental variations, thus solving the problem of temperature sensing hysteresis in external sensors. High Compensation Accuracy: Since this invention directly measures the temperature effect of the resistive element itself—i.e., resistance change—rather than estimating temperature, the compensation is direct and accurate, requiring no complex temperature-resistance model. Good Long-Term Stability: In the manufacturing method of this invention, the two resistors originate from the same material and undergo the same process; therefore, their responses to long-term aging (such as resistance drift) are highly consistent. The "tracking" ability of the reference resistor to the sampling resistor does not significantly decrease with increasing usage time. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the current sensing element structure of the present invention;

[0022] Figure 2 This is a cross-sectional view of the current sensing element of the present invention;

[0023] Figure 3 This is a schematic diagram of the current sensing element of the present invention before filling the substrate;

[0024] Figure 4 This is a flowchart of the manufacturing method of the current sensing element of the present invention. Detailed Implementation

[0025] Example 1

[0026] like Figure 1 and Figure 2As shown, the present invention proposes an integrated dual-resistance current sensing element, comprising a resistor body, a filling layer 1, a sampling resistor region 2, a reference resistor region 3, a first electrode 4, a second electrode 5, a package 6, and a channel 7. The channel 7 is etched onto the resistor body, formed by laser etching, mechanical cutting, or chemical etching. The width of the channel 7 is 50μm to 500μm. The resistor body is physically separated into the sampling resistor region 2 and the reference resistor region 3 by the channel 7. The resistor body is made of a low-temperature coefficient resistance alloy material, such as manganese-copper alloy or nickel-chromium alloy, and its shape is a thin film or foil. A filling layer 1 is disposed within the channel 7, with one side of the filling layer 1 contacting the sampling resistor region 2 and the other side contacting the reference resistor region 3. The filling layer 1 is made of an insulating thermally conductive adhesive, serving to support the resistor body and achieve thermal connection with the external heat dissipation path. Although sampling resistor region 2 and reference resistor region 3 are electrically isolated, they are derived from the same material block and are very close together. Through the insulating thermally conductive adhesive in between and the extremely low thermal resistance of their own materials, they achieve near-ideal thermal coupling, ensuring that sampling resistor region 2 and reference resistor region 3 maintain the same temperature during operation. The first electrode 4 is a thick copper electrode plated with nickel and then tin, and the second electrode 5 is a gold-plated electrode. The size of the first electrode 4 is larger than that of the second electrode 5.

[0027] The first electrode 4 is fixed to both ends of the sampling resistor region 2 by welding or electroplating. The first electrode 4 is used to carry load currents of amperes or above and usually has a large area and low resistance. The second electrode 5 is fixed to both ends of the reference resistor region 3 by welding or electroplating. The second electrode 5 is used to connect to external weak measurement circuits (such as constant current sources and high input impedance ADCs), and its design focuses more on contact reliability and low thermoelectric potential.

[0028] The filling layer 1, sampling resistor region 2, and reference resistor region 3 are sealed by the encapsulation body 6 for protection. The high-current motor 4 and the second electrode 5 extend out of the encapsulation body 6 and contact the outside environment for subsequent measurements. The thickness of the encapsulation body 6 on the upper surface of the sampling resistor region 2 is less than the thickness of the encapsulation body 6 on the upper surface of the reference resistor region 3. The encapsulation body 6 is thinned or has windows in the upper surface area corresponding to the sampling resistor region 2 to optimize the heat dissipation capacity of the sampling resistor region 2 to the environment. The encapsulation body on the upper surface of the reference resistor region 3 maintains a standard thickness to reduce the influence of ambient airflow fluctuations on the reference resistor region 3. The encapsulation body is made of insulating material, using epoxy resin and silicone.

[0029] Example 2

[0030] like Figure 3 and Figure 4 As shown, a method for manufacturing an integrated dual-resistance current sensing element includes the following steps:

[0031] Step 1: Provide a uniformly doped resistor body. The resistor body can be selected from manganese copper alloy or nickel chromium alloy.

[0032] Step 2: A channel 7 is formed on the resistor body in Step 1 by laser etching, mechanical cutting or chemical etching to divide the resistor body into a sampling resistor area 2 and a reference resistor area 3. The width of the channel 7 is 50μm to 500μm.

[0033] Step 3: Fill the channel 7 in step 2 with thermally conductive insulating adhesive and cure it to form a filling layer 1. The two sides of the filling layer 1 are respectively attached to the sampling resistor area 2 and the reference resistor area 3.

[0034] Step 4: The first electrode 4 is fixed at both ends of the sampling resistor region 2 in step 3 by electroplating or welding, and the second electrode 5 is fixed at both ends of the reference resistor region 3 by electroplating or welding. The first electrode 4 is a thick copper electrode that is plated with nickel and then tin, and the second electrode 5 is a gold-plated electrode. The size of the first electrode 4 is larger than the size of the second electrode 5.

[0035] Step 5: Prepare a package 6 on the surface of the filling layer 1, the sampling resistor region 2 and the reference resistor region 3, with the first electrode 4 and the second electrode 5 extending out of the package 6, to obtain a rough current sensing element.

[0036] Step 6: Perform high-temperature aging and power load screening tests on the crude current sensing element to eliminate elements with inconsistent drift, and obtain the final current sensing element.

[0037] High-temperature aging: The components are placed in a constant temperature environment of 85℃~125℃ for 24h~168h to allow the internal stress of the components to be fully released and the resistance value to stabilize.

[0038] Power load screening applies 50% to 100% of the rated power to sampling resistor region 2 and continues for 1 to 24 hours to simulate actual high current operating conditions. The resistance changes of the sampling resistor region and the reference resistor region are monitored simultaneously to screen out components whose drift trends are highly consistent.

[0039] like Figures 1 to 3 As shown, the resistor body of the integrated dual-resistance current sensing element manufactured above is made of a thin film of manganese-copper alloy. A 50-micrometer-wide channel 7 is laser-etched into the resistor body, dividing it into a sampling resistor region 2 on the left and a reference resistor region 3 on the right. The sampling resistor region 2 and the reference resistor region 3 are electrically isolated. A filling layer 1 is provided inside the channel 7. The filling layer 1 is a high-polymer thermally conductive insulating adhesive, thereby ensuring insulation and efficient thermal coupling between the sampling resistor region 2 and the reference resistor region 3. The first electrode 4 is a thick copper electrode plated with nickel and then tin, which is welded to both ends of the sampling resistor region 2. The second electrode 5 is a NiCr / Ni / Au multilayer electrode, which is welded to both ends of the reference resistor region 3. The package 6 is molded from black epoxy resin, sealing the filling layer 1, the sampling resistor region 2, and the reference resistor region 3. The first electrode 4 and the second electrode 5 extend out of the package 6 and come into contact with the outside.

[0040] During operation, the load current flows in through the first electrode 4 on one side of the sampling resistor region 2, passes through the sampling resistor region 2, and then flows through the first electrode 4 on the other side of the sampling resistor region 2, generating a millivolt-level sampling voltage V. sense An external precision measurement circuit injects a constant current of 100 microamps into the reference resistor region 3 through the second electrodes 5 at both ends, and measures the voltage V across the reference resistor region 3. ref Due to thermal coupling, the resistance R of reference resistor region 3... ref The resistance value R of sampling resistor region 2 sense It changes synchronously with temperature. (According to formula I) load =V sense / R ref Calculate the load current.

Claims

1. An integrated dual-resistor current sensing element, characterized by, The resistor body includes a resistor body and a package (6) disposed around the resistor body. The resistor body is etched with a channel (7) to divide the resistor body into a sampling resistor region (2) and a reference resistor region (3). A filling layer (1) is disposed in the channel (7). One end of the filling layer (1) is connected to the sampling resistor region (2) and the other end is connected to the reference resistor region (3). The sampling resistor region (2) and the reference resistor region (3) are electrically insulated but thermally coupled. A first electrode (4) is disposed at both ends of the sampling resistor region (2) and a second electrode (5) is disposed at both ends of the reference resistor region (3).

2. The integrated dual-resistor current sense element of claim 1, wherein, The width of the channel (7) is 50μm to 500μm.

3. The integrated dual-resistor current sense element of claim 1, wherein, The filler layer (1) is made of thermally conductive insulating adhesive.

4. The integrated dual-resistor current sense element of claim 1, wherein, The resistor body material is a manganese copper alloy, a nickel-chromium alloy, or an Evan alloy; the resistor body shape is a thin film or a foil.

5. The integrated dual-resistor current sense element of claim 1, wherein, Several first electrodes (4) are fixed at both ends of the sampling resistor region (2), and the first electrodes (4) pass through the package (6) and contact the outside. The second electrodes (5) are fixed at both ends of the reference resistor region (3), and one end of the second electrodes (5) extends out of the package (6) and contacts the outside. The first electrodes (4) are thick copper electrodes plated with nickel and then tin, and the second electrodes (5) are gold-plated electrodes. The size of the first electrodes (4) is larger than the size of the second electrodes (5).

6. The integrated dual-resistor current sense element of claim 1, wherein, The thickness of the package (6) on the side of the sampling resistor region (2) away from the filling layer (1) is less than the thickness of the package (6) on the side of the reference resistor region (3) away from the filling layer (1).

7. The integrated dual-resistor current sense element of claim 1, wherein, The encapsulation body (6) is an insulating material, preferably epoxy resin or silicone.

8. A method for manufacturing an integrated dual-resistance current sensing element according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Provide a uniformly doped resistor body; Step 2: Etch a channel (7) on the resistor body in Step 1 to divide the resistor body into a sampling resistor area (2) and a reference resistor area (3); Step 3: Prepare a filling layer (1) in the channel (7) in step 2. The filling layer (1) is attached to the sampling resistor region (2) and the reference resistor region (3) on both sides respectively. Step 4: A first electrode (4) is formed at both ends of the sampling resistor region (2) in step 3, and a second electrode (5) is formed at both ends of the reference resistor region (3); Step 5: Prepare a package (6) on the surface of the filling layer (1), the sampling resistor region (2) and the reference resistor region (3), with the first electrode (4) and the second electrode (5) extending out of the package (6) to obtain a rough current sensing element; Step 6: Perform high-temperature aging and power load screening tests on the crude current sensing element to eliminate elements with inconsistent drift, and obtain the final current sensing element.

9. The method for manufacturing the integrated dual-resistance current sensing element according to claim 8, characterized in that, The first electrode (4) and the second electrode (5) are fixed by electroplating or welding. The first electrode (4) is a thick copper electrode that is plated with nickel and then tin, and the second electrode (5) is a NiCr / Ni / Au multilayer electrode. The size of the first electrode (4) is larger than that of the second electrode (5).

10. The method for manufacturing the integrated dual-resistance current sensing element according to claim 8, characterized in that, The channel (7) is formed by laser etching, mechanical cutting or chemical etching. The width of the channel (7) is 50μm to 500μm. The filling layer (1) is made of thermally conductive insulating adhesive.

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