An integrated current sensor based on magnetic ceramic material and a manufacturing method thereof

Abstract

The application discloses an integrated current sensor based on a magnetic ceramic material and a manufacturing method thereof, relates to the technical field of current sensors, and comprises annular magnetic ceramic substrates which are connected through two annular framework structures, the two framework structures are respectively located at inner and outer rings, and the framework joints in the two framework structures correspond to each other; circuit lines, sampling resistors and damping resistors are integrally arranged in the top and bottom of the magnetic ceramic substrates, the circuit lines are connected with the framework structures to form spiral winding coils, and the output ends of the winding coils are electrically connected with the sampling resistors; and the damping resistors are provided in plurality and are connected in parallel to the winding coils, so that the problems of large volume and low reliability of a traditional current sensor are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of current sensor, in particular to an integrated current sensor based on magnetic ceramic material and a manufacturing method thereof. BACKGROUND

[0002] With the rapid development of power electronics technology and high-power systems, system devices are constantly moving towards miniaturization, lightweight and high integration; under this background, the accurate detection of the current of the key electrical link inside the system becomes particularly important, especially in the application scenarios of high-density power conversion and transmission in limited space, which puts forward more stringent requirements for current sensors: not only high measurement accuracy, wide dynamic frequency response range and strong anti-interference ability, but also compact structure, easy integration and high reliability design requirements.

[0003] At present, in the field of high-precision current measurement, Rogowski Coil current sensors are widely used due to their non-contact measurement, wide frequency band and good linearity. The more mature implementation schemes in the prior art mainly include two types:

[0004] The first type is a hollow ring structure scheme, which adopts an insulating wire uniformly wound on a non-magnetic ring-shaped skeleton, and its working principle is based on Faraday's law of electromagnetic induction; when the measured current-carrying conductor passes through the center of the coil, the alternating magnetic field generated will induce an induced electromotive force proportional to the current rate of change (di / dt) at both ends of the coil. In order to restore the original current signal, an external analog integration circuit (such as an RC active integrator) or a digital integration algorithm must be used to process the induced signal.

[0005] The advantage of this scheme is that there is no magnetic saturation phenomenon, and the linearity is excellent. However, due to the lack of magnetic field concentration of the magnetic core, it is often necessary to increase the number of turns of the coil or the cross-sectional area of the conductor to improve the sensitivity, which directly leads to a significant increase in the size of the sensor, making it difficult to adapt to the trend of device miniaturization.

[0006] The second type is a closed structure scheme with a magnetic core, which selects a high magnetic permeability magnetic material to make a ring-shaped magnetic core, and tightly winds the sensing coil on the surface of the magnetic core to form a closed magnetic circuit. The use of the magnetic core can effectively concentrate the magnetic force lines, reduce the magnetic resistance and leakage of the magnetic circuit, and enhance the magnetic field coupling efficiency through its high magnetic permeability characteristics. The structure itself has a certain integration effect, so that the electromotive force induced by the coil can be directly converted into a voltage signal proportional to the measured current through a simple sampling resistor, thereby eliminating the need for complex external integration links.

[0007] Although the magnetic core scheme reduces the size of the magnetic circuit to some extent, it still belongs to a discrete structure in essence - the magnetic core and the coil are usually independently manufactured and then combined through subsequent assembly processes. This discrete mode limits the further compression of the sensor volume, making it difficult to meet the requirements of ultra-high integration of modern systems.

[0008] Chinese patent CN114783711A discloses a method for manufacturing a resistor on the surface of an aluminum nitride high-temperature co-fired ceramic substrate. Although the resistor element is integrated on the ceramic substrate through a specific process (laser etching / thick film printing) to achieve the built-in and high performance of electronic components, this method cannot be directly applied to the design of current sensors.

[0009] Therefore, we propose a current sensor with small volume and high reliability. SUMMARY

[0010] The purpose of the present application is to provide an integrated current sensor based on magnetic ceramic material and a manufacturing method thereof, which solves the problems of large volume and low reliability of traditional current sensors.

[0011] The present application is achieved by the following technical solutions:

[0012] An integrated current sensor based on magnetic ceramic material, comprising a circular ring-shaped magnetic ceramic substrate, two annular skeleton structures are arranged in the circular ring-shaped magnetic ceramic substrate, the two skeleton structures are located at the inner circle and the outer circle respectively, and the bones in the two skeleton structures correspond one by one;

[0013] The top and bottom of the magnetic ceramic substrate are integrally integrated with circuit lines, sampling resistors and damping resistors, wherein the circuit lines are connected with the skeleton structure to form a spiral winding coil, and the output end of the winding coil is electrically connected with the sampling resistor; the damping resistor is provided as a plurality of damping resistors connected in parallel to the winding coil.

[0014] Further, the distance between adjacent circuit lines in the winding coil is 50-100 .

[0015] Further, the top and bottom of the magnetic ceramic substrate are provided with a metal shielding layer.

[0016] Further, the magnetic ceramic substrate, circuit lines, sampling resistors and damping resistors are integrated into an integrated structure by a low-temperature co-firing process.

[0017] Further, the circuit lines include straight circuit lines and bent circuit lines.

[0018] The winding coil is composed of a plurality of basic units connected in sequence, wherein the basic unit comprises a straight circuit line, a bent circuit line, a first bone joint of an outer ring skeleton structure, and a third bone joint of an inner ring skeleton structure, the head end of the straight circuit line is electrically connected with the top end of the first bone joint of the outer ring skeleton structure, the bottom end of the first bone joint of the outer ring skeleton structure is electrically connected with the bent end of the bent circuit line, and the straight end of the bent circuit line is electrically connected with the bottom end of the third bone joint of the inner ring skeleton structure.

[0019] The tail end of the straight circuit line and the top end of the third bone joint of the inner ring skeleton structure are respectively used for electrical connection with other basic units.

[0020] A manufacturing method of an integrated current sensor based on a magnetic ceramic material, specifically comprising:

[0021] S1. Mix the magnetic ceramic powder, organic binder and solvent according to a preset ratio, and then obtain a plurality of green ceramic tapes through a flow casting process;

[0022] S2. Perform a punching operation on the surface of each green ceramic tape to obtain a through hole, and open a blind hole on the surface of two green ceramic tapes;

[0023] S3. Form corresponding circuit lines, sampling resistors and damping resistors in the blind holes by using a screen printing process; select a conductive paste mixed with silver powder, borosilicate and glass powder, and fill the through holes by using a vacuum hole filling machine to form metal nodes;

[0024] S4. Correspond the metal nodes of the plurality of green ceramic tapes one by one to form a skeleton structure, and then stack to form a sensor prototype;

[0025] S5. Use an isostatic pressing machine to press the sensor prototype at a pressure of 20 MPa and a temperature of 70℃ for 10-15 minutes;

[0026] S6. Heat the sensor prototype after pressure retention to 450℃ at a rate of 2-5℃ / min, and keep warm for 1.5-2 hours;

[0027] S7. Rapidly heat the sensor prototype after heat preservation to 850-900℃, keep warm for 20 minutes, and obtain a current sensor;

[0028] S8. Cut the current sensor, electroplate the end electrode, and detect the appearance to obtain a current sensor finished product.

[0029] Further, in the S1, the magnetic ceramic powder is a nickel-zinc ferrite, the organic binder is polyvinyl butyl, the solvent is butyl carbitol, and the mixing is performed by using a ball mill.

[0030] Further, in the S2, for the through hole or blind hole with a hole diameter <100 , a laser punching machine is used for operation; for the through hole or blind hole with a hole diameter >100 If the through hole is not provided, a mechanical punching operation is performed using a hard alloy punch.

[0031] Further, the sampling resistor and the damping resistor in S3 have a resistivity of 100-150 .

[0032] Further, after the corresponding circuit line, the sampling resistor and the damping resistor are formed in the blind hole by the screen printing process, the green ceramic tape needs to be dried by hot air at 80 DEG C for 10 minutes.

[0033] The technical scheme of the present application has at least the following advantages and beneficial effects:

[0034] The application discloses an integrated current sensor based on a magnetic ceramic material and a manufacturing method thereof, and the integrated current sensor is prepared by combining a magnetic ceramic material with high magnetic permeability and a multilayer ceramic co-firing process, and the cross layout of a magnetic circuit and an electric circuit is realized by using a multilayer ceramic lamination technology, so that the layout can be reasonably arranged in limited space, and the problem of bulky volume caused by the dispersed arrangement of elements in a traditional structure is avoided. Meanwhile, the integrated design makes the elements closely combined, unnecessary space occupation is reduced, and the volume and the integration degree have strong competitiveness, so that the integrated current sensor can better adapt to the requirements of miniaturization and high integration degree of modern electronic equipment.

[0035] In addition, the sampling resistor and the damping resistor are directly integrated in the ceramic substrate and electrically connected with the winding coil, so that the parasitic inductance and the parasitic capacitance introduced by traditional external elements are effectively avoided, the signal distortion and the resonance risk under high frequency are greatly reduced, the working bandwidth of the sensor is widened, the flatness of the frequency response is improved, and the precision in high dynamic range current measurement is ensured.

[0036] In addition, the magnetic ceramic substrate and all internal circuit elements are made into an integrated structure by using a low-temperature co-firing process, and have excellent structural strength, vibration resistance and impact resistance, and the ceramic substrate itself has air tightness, so that the sensor can stably work in a humid and dusty environment, and the reliability during long-term use is significantly improved.

[0037] In particular, the metal shielding layer is arranged on the top surface and the bottom surface of the magnetic ceramic substrate, so that the influence of external electromagnetic interference on the internal sensitive sensing circuit can be effectively inhibited, the external radiation of the magnetic field of the sensor itself can be reduced, and the signal-to-noise ratio and the measurement stability in a complex electromagnetic environment are improved. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 Fig. 1 is a structural schematic diagram of an integrated current sensor based on a magnetic ceramic material according to the present application.

[0039] Figure 2 A schematic diagram of a skeleton structure of the present application;

[0040] Figure 3 A schematic diagram of the structure of A in Figure 2 ;

[0041] Figure 4 An equivalent circuit diagram of an integrated current sensor based on magnetic ceramic material of the present application;

[0042] Figure 5 A flow chart of the manufacturing method of an integrated current sensor based on magnetic ceramic material of the present application.

[0043] Reference signs: 1, magnetic ceramic substrate; 2, skeleton structure; 3, circuit line; 31, straight circuit line; 32, bent circuit line; 4, sampling resistor; 5, damping resistor; 6, current line to be measured; 7, metal shielding layer. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0045] Embodiment 1

[0046] As shown in Figures 1-3 , an integrated current sensor based on magnetic ceramic material comprises a circular ring-shaped magnetic ceramic substrate 1, two annular skeleton structures 2 are arranged in the circular ring-shaped magnetic ceramic substrate 1, the two skeleton structures 2 are respectively located at the inner circle and the outer circle, and the bones in the two skeleton structures 2 correspond one by one;

[0047] The top and bottom of the magnetic ceramic substrate 1 are integrally integrated with circuit lines 3, sampling resistors 4 and damping resistors 5, wherein the circuit lines 3 are connected with the corresponding skeleton structures 2 to form spiral winding coils, and the output ends of the winding coils are electrically connected with the sampling resistors 4; the damping resistors 5 are provided in plurality, and the plurality of damping resistors 5 are connected in parallel to the winding coils;

[0048] In particular, the distance between adjacent circuit lines 3 in the winding coil is 50-100 Thus, on the limited surface area of the annular ceramic substrate, more coil turns can be arranged in unit area, and higher turns can significantly enhance the induced electromotive force, thereby improving the sensor's detection capability for tiny current, and to achieve the same sensitivity and turns, the design with fine line width / line spacing can be much smaller than the traditional hand-wound coil, perfectly meeting the core demand of "miniaturization";

[0049] In addition, the circuit line 3 includes a straight circuit line 31 and a bent circuit line 32;

[0050] The winding coil is composed of a plurality of basic units connected in sequence, wherein the basic unit includes the straight circuit line 31, the bent circuit line 32, the first bone segment of the outer circle skeleton structure, and the third bone segment of the inner circle skeleton structure, the head end of the straight circuit line 31 is electrically connected to the top end of the first bone segment of the outer circle skeleton structure, the bottom end of the first bone segment of the outer circle skeleton structure is electrically connected to the bent end of the bent circuit line 32, and the straight end of the bent circuit line 32 is electrically connected to the bottom end of the third bone segment of the inner circle skeleton structure;

[0051] It should be noted that the straight circuit line 31 is located on the inner top surface of the magnetic ceramic substrate 1, and the bent circuit line 32 is located on the inner bottom surface of the magnetic ceramic substrate 1, and the "first" and "third" in the first bone segment of the outer circle skeleton structure and the third bone segment of the inner circle skeleton structure are only used to distinguish the relative positions between the bone segments in the two skeleton structures, that is, there is one bone segment corresponding to the interval between the first bone segment and the third bone segment;

[0052] The tail end of the straight circuit line 31 and the top end of the third bone segment of the inner circle skeleton structure are respectively used for electrical connection with other basic units, more specifically, the tail end of the straight circuit line 31 is electrically connected to the top end of the bone segment of the inner circle skeleton structure in another basic unit, and the top end of the third bone segment of the inner circle skeleton structure is electrically connected to the head end of the straight circuit line 31 in another basic unit, thereby forming a spiral winding coil after being connected in sequence.

[0053] And the winding coil described above, as shown in Figure 2 and Figure 3 It can also be staggered with the winding coil after reversing the direction to form a loop structure, the purpose of which is to effectively improve the electromagnetic interference immunity of the sensor. In this structure, the external uniform interference magnetic field induces an electromotive force of equal size and opposite direction in adjacent but opposite direction coil segments, which cancel each other out, so that the net induced voltage of the entire coil to the external interference field is close to zero, significantly suppressing the influence of common-mode interference on the output signal, and improving the measurement accuracy and stability of the sensor in complex electromagnetic environment.

[0054] In addition, the fine and uniform wiring can effectively control and reduce the distributed capacitance and parasitic inductance of the coil, since the distributed capacitance is the main factor limiting the high frequency response of the Rogowski coil, reducing the distributed capacitance can push the resonant frequency of the sensor to a higher frequency band, thereby expanding its effective working bandwidth; and the more uniform wire spacing avoids the problem of local capacitance concentration and multiple resonance points caused by inconsistent spacing in traditional winding, making the frequency response of the sensor more flat in a wide frequency band, and the measurement result more accurate.

[0055] In addition, the middle part of the circular ring of the magnetic ceramic base 1 is used for the measured current line 6 to pass through, so that the magnetic ceramic base 1 can gather, guide and significantly enhance the magnetic field generated by the measured current, wherein the principle of the current sensor measuring the measured current line 6 is that:

[0056] As shown in the equivalent circuit diagram shown in Figure 4 , when the sensor is working, the coil output end is terminated by a terminal sampling resistor , in the figure , I represents the measured current flowing in the measured current wire, is the induced current in the closed coil, is the winding resistance of the induction coil, is the distributed capacitance of the induction coil, is the self-inductance of the induction coil, is the mutual inductance between the measured current wire and the current sensor, represents the induced electromotive force of the current sensor, is an embedded damping resistor network used to suppress the parasitic resonance effect brought by the multi-turn Rogowski coil structure, is the rated voltage;

[0057] When the measured current line 6 passes through the center of the sensor circular ring, according to the Ampere loop law, the current will generate an alternating magnetic field around the measured current line 6, which is proportional to the rate of change of the current, and then according to the Faraday's law of electromagnetic induction, when the alternating magnetic field generated by the measured current line 6 passes through the winding coil of the current sensor, an electromotive force will be induced in the coil;

[0058] And the current sensor in the signal conversion and output, due to winding coil, sampling resistance 4 and damping resistance 5 network together constitute an equivalent circuit, and the induced electromotive force will be in the closed loop of the coil to produce an induced current; thus in a specific frequency range, that is, when the coil self-inductance reactance is much larger than the total resistance of the loop, the sensor works in the self-integral mode, in this mode, the induced current is proportional to the current to be measured, the induced current flows through the terminal embedded sampling resistance 4, according to Ohm's law, it can be converted into a voltage output signal that can be directly measured, therefore, the final output voltage output signal is proportional to the current itself, and no longer need external complex integral circuit to restore the current rate signal, finally according to the sensitivity coefficient of the sensor, the actual measured current value can be converted.

[0059] Example 2

[0060] The top and bottom of the magnetic ceramic substrate 1 are provided with a metal shielding layer 7;

[0061] Because in the actual working environment, especially in high-power power electronic system, there are a large number of complex electromagnetic noise sources around the sensor, such as switching power supply, high-frequency oscillation, magnetic field of adjacent conductor, etc.; through the metal shielding layer 7, a Faraday cage is formed, which can effectively block and absorb these external electric field and high-frequency magnetic field; thereby preventing external noise from coupling into the internal sensitive induction coil, significantly reducing the noise in the output signal, thereby greatly improving the signal-to-noise ratio and measurement accuracy of the sensor.

[0062] And the magnetic ceramic substrate 1 can effectively concentrate the magnetic flux, but part of the magnetic field will leak out from the top and bottom, the metal shielding layer 7 provides a low magnetic resistance closed path for these stray magnetic fields, "restricts" them inside the sensor, so that more magnetic flux is guided through the induction coil, enhancing the efficiency of the magnetic field, indirectly improving the sensitivity, and reducing the electromagnetic interference of the sensor's own magnetic field to other sensitive circuits outside, making the system integration more stable and reliable.

[0063] In addition, the metal shielding layer 7 is usually connected to the ground potential of the system, providing a stable and clean reference ground plane for the internal signals of the sensor, and forming a controllable transmission line structure with the internal signal lines, which helps to maintain the stability of the signal transmission path impedance and reduce signal reflection; and provides a low-impedance discharge path for common-mode interference current to prevent it from affecting the differential signal.

[0064] In addition, under the high-speed changing current signal, each segment of the lead wire of the Rogowski coil has a distributed inductance and a ground / turn-to-turn capacitance, which makes the coil itself a complex distributed parameter circuit, so that when the coil is long, it will resonate at multiple frequency points, forming multiple resonance peaks, which seriously distorts the frequency response.

[0065] Therefore, by spacing four circuit lines 3 between two adjacent damping resistors 5, the entire long coil is effectively divided into several segments with very short electrical lengths. Each damping resistor 5 is responsible for suppressing the high-frequency resonance of its respective coil segment. This distributed design can more effectively and evenly flatten the entire frequency response curve, eliminate multiple resonance points, thereby expanding the working bandwidth of the sensor and ensuring accurate measurement results even at high frequencies.

[0066] Furthermore, this design method can provide damping at a sufficient number of points to ensure effectiveness, while avoiding excessive sensitivity loss due to overly dense resistor arrangement. Thus, while ensuring sufficient suppression of resonance, it maximizes the retention of sensor sensitivity and achieves the best performance balance.

[0067] Meanwhile, using fixed and regular intervals makes the distribution parameters of the damping network uniform and predictable, ensuring that mass-produced sensors have highly consistent frequency response characteristics. The regular distribution also allows engineers to accurately predict its impact through simulation during the design phase and compensate for it in circuit design, which greatly improves product yield and design reliability.

[0068] Example 3

[0069] like Figure 5 The method for fabricating an integrated current sensor based on magnetic ceramic materials, as shown, specifically includes:

[0070] S1. Mix magnetic ceramic powder, organic binder and solvent in a preset ratio, and then obtain multiple green ceramic tapes through a casting process;

[0071] The use of nickel-zinc ferrite as the magnetic ceramic powder ensures high magnetic permeability of the substrate, providing an efficient path for magnetic field coupling. The addition of polyvinyl butyral organic binder and butyl carbitol solvent, mixed at high speed using a ball mill, aims to form a uniform, bubble-free slurry. Subsequently, by precisely controlling the blade gap, a slot-cast coating machine is used for application, followed by drying in a hot air tunnel at 60-80℃ for 15-20 minutes, resulting in a uniform thickness and a smooth surface (surface roughness less than 0.5). The green ceramic tape, with its excellent flexibility, provides a reliable dielectric material basis for subsequent screen printing and multilayer lamination, which is the primary guarantee for achieving consistent sensor performance.

[0072] In addition, the preset ratio of magnetic ceramic powder, organic binder and solvent is as follows: magnetic ceramic powder 80%-85%, organic binder 7%-10% and solvent 10%-12%, and the specific ratio can be: nickel-zinc ferrite powder 80%, polyvinyl butyral 9%, butyl carbitol 11%;

[0073] S2. The surface of each green ceramic tape is punched to obtain through holes, and the surface of two green ceramic tapes is punched to obtain blind holes;

[0074] For through holes or blind holes with a hole diameter <100 , a laser puncher is used, and the quality of the hole wall is controlled by adjusting the pulse energy and frequency during the operation to avoid slag residues; for through holes with a hole diameter >100 , a mechanical puncher with a hard alloy punch is used;

[0075] S3. The corresponding circuit line 3, sampling resistor 4 and damping resistor 5 are formed in the blind hole by using a screen printing process. Before screen printing, the nickel-chromium thick film resistor paste is prepared according to the design requirements. The resistivity of the paste is 100-150 , and the sintering shrinkage can be controlled by adjusting the ratio of nickel-chromium to glass powder, and the viscosity can be adjusted by adding an organic carrier. When screen printing, the deviation of the line distance should be ≤±5 . After printing, the green ceramic tape is dried by hot air at 80°C for 10 minutes to reduce solvent residues. Then, the resistance value of the unsintered resistor layer is tested by the four-probe method, and the deviation should be ≤±10%;

[0076] The conductive paste of silver powder, borosilicate and glass powder is selected to fill the through hole by a vacuum hole filling machine. The pressure of the vacuum hole filling machine is -0.08 MPa to form a metal node, and the protrusion height of the metal node is ≤5 . In addition, the hole filling quality needs to be detected by X-ray perspective to ensure that there is no cavity or bubble, and the consistency of the hole filling height is verified by a laser height gauge;

[0077] S4. The metal nodes of multiple green ceramic tapes are one-to-one corresponding. The positioning is performed by using a positioning pin or an optical alignment system for accurate alignment between layers to form a skeleton structure 2. The metal guide rods correspond to form a bone joint, and then the sensor prototype is stacked;

[0078] It should be noted that when stacking, the first to second layers from top to bottom are green ceramic tapes containing only through holes, the third layer is a green ceramic tape containing blind holes, the fourth layer to the fourth layer from bottom to top are green ceramic tapes containing only through holes, the third layer from bottom to top is a green ceramic tape containing blind holes, and the first to second layers from bottom to top are green ceramic tapes containing only through holes. The first to second layers and the first to second layers from bottom to top are metal shielding layers 7, the third layer and the third layer from bottom to top are wire layers, and the remaining layers are structure layers;

[0079] In addition, the blind hole for screen printing the circuit line 3 is connected to the through hole at both ends, which can ensure that the circuit line 3 and the skeleton structure 2 formed by multiple metal nodes can form a path, and finally form a winding coil.

[0080] S5. Adopting isostatic press to keep pressure on sensor prototype for 10~15 minutes under 20MPa pressure and 70℃ temperature, so as to make the layers closely combined and the pressure decay rate <5%, while the layering quality of the sensor prototype needs to be detected by X-ray perspective to check the layering deviation (allowable deviation ≤10 ), and ultrasonic scanning is used to check the internal cavity or layering to ensure the structural integrity;

[0081] S6. The sensor prototype after pressure keeping is heated to 450℃ at a rate of 2~5℃ / min, and kept for 1.5~2 hours, which is a degassing step. Slow heating rate and long time keeping at 450℃ are used to make the organic binder (PVB, etc.) in the green ceramic tape decompose and volatilize smoothly and sufficiently. If the temperature is raised too fast, the organic matter will be rapidly gasified, which will cause the product to bubble, crack or have cavities. This step can completely remove the organic matter, providing a clean substrate for subsequent high-temperature sintering, and is a prerequisite for obtaining a dense and defect-free ceramic structure.

[0082] S7. The sensor prototype after keeping is quickly heated to 850~900℃ and kept for 20 minutes to obtain a current sensor. This step is a sintering stage, which is the key to realizing the integration of ceramic medium and metal conductor. At the low-temperature co-firing temperature of 850~900℃, diffusion and fusion occur between the particles of the magnetic ceramic powder, and the ceramic substrate is densified to form a hard ceramic base. At the same time, the internal silver conductor paste is sintered at this temperature to form a firm chemical bond and ohmic contact with the ceramic base. This process finally integrates the green ceramic tape and all the embedded elements (circuit, resistor, vertical interconnection) into a single, high-strength three-dimensional structure, realizing the integration of the magnetic circuit and the circuit. In addition, the atmosphere needs to be controlled during sintering. If copper is used for hole filling, it needs to be in a nitrogen or hydrogen-nitrogen mixed atmosphere. In addition, the resistance value needs to be re-measured after sintering to verify the sintering effect.

[0083] S8. The current sensor is cut, the end electrode is plated, and the appearance is detected to obtain the current sensor product, i.e. the magnetic ceramic base 1. The cutting step is to use a diamond grinding machine to cut the sintered body to ensure that the edge has no burrs. The end electrode plating is to form the end electrode by chemical nickel plating and tin plating. The nickel layer acts as a barrier layer to prevent the migration of the silver internal electrode, and the tin layer provides excellent weldability and oxidation resistance to prevent oxidation and improve welding reliability. The final appearance detection is to check cracks, delamination and other defects by AOI (Automated Optical Inspection), and to verify the thickness and uniformity of the end electrode plating layer by XRF (X-Ray Fluorescence), to ensure that it meets the design specifications.

[0084] The current sensor made by the manufacturing method completely eliminates the assembly space and interface of traditional discrete components, and more coil turns can be wound on the limited annular substrate, so that high sensitivity is realized in a small volume, and the contradiction between miniaturization and high sensitivity is solved.

[0085] The preferred embodiments of the present application have been described above with the preferred embodiments, but the present application is not limited to the above examples, and various modifications and changes can be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An integrated current sensor based on magnetic ceramic material, characterized in that, It includes a circular magnetic ceramic substrate (1), and two circular skeleton structures (2) are set inside the circular magnetic ceramic substrate (1). The two skeleton structures (2) are located in the inner circle and the outer circle respectively, and the joints in the two skeleton structures (2) correspond one to one. The magnetic ceramic substrate (1) has integrated circuit lines (3), sampling resistors (4) and damping resistors (5) on both the top and bottom. The circuit lines (3) are connected to the skeleton structure (2) to form a spiral winding coil. The output end of the winding coil is electrically connected to the sampling resistor (4). Multiple damping resistors (5) are connected in parallel to the winding coil. The circuit lines (3) include straight circuit lines and bent circuit lines; The winding coil is composed of multiple basic units connected in sequence. The basic unit includes a straight circuit line (31), a bent circuit line (32), a first segment of the outer ring skeleton structure and a third segment of the inner ring skeleton structure. The head end of the straight circuit line (31) is electrically connected to the top end of the first segment of the outer ring skeleton structure, the bottom end of the first segment of the outer ring skeleton structure is electrically connected to the bent end of the bent circuit line (32), and the straight end of the bent circuit line (32) is electrically connected to the bottom end of the third segment of the inner ring skeleton structure. The tail end of the straight circuit line (31) and the top end of the third segment of the inner ring skeleton structure are used for electrical connection with other basic units, respectively.

2. The integrated current sensor based on magnetic ceramic material according to claim 1, characterized in that: The spacing between adjacent circuit lines (3) in the winding coil is 50~100 mm. .

3. The integrated current sensor based on magnetic ceramic material according to claim 1, characterized in that: The magnetic ceramic substrate (1) is provided with metal shielding layers (7) at both the top and bottom.

4. The integrated current sensor based on magnetic ceramic material according to claim 1, characterized in that: The magnetic ceramic substrate (1), circuit line (3), sampling resistor (4) and damping resistor (5) are integrated into a single structure using a low-temperature co-firing process.

5. A method for fabricating an integrated current sensor based on magnetic ceramic materials, comprising the integrated current sensor based on magnetic ceramic materials as described in any one of claims 1-4, characterized in that, Specifically, it includes: S1. Mix magnetic ceramic powder, organic binder and solvent in a preset ratio, and then obtain multiple green ceramic tapes through a casting process; S2. Drill holes on the surface of each green ceramic strip to obtain through holes, and make blind holes on the surface of two of the green ceramic strips; S3. The corresponding circuit lines (3), sampling resistors (4) and damping resistors (5) are formed in the blind holes using screen printing technology; a conductive paste made of silver powder, borosilicate and glass powder is selected and the through holes are filled by a vacuum filling machine to form metal nodes; S4. The metal nodes of multiple green ceramic strips are matched one by one to form a skeleton structure (2), and then stacked to form a sensor prototype; S5. The sensor prototype is pressurized at 20MPa and 70℃ for 10-15 minutes using an isostatic press. S6. Heat the pressure-held sensor prototype to 450℃ at a rate of 2~5℃ / min, and hold for 1.5~2 hours; S7. Rapidly heat the heat-insulated sensor prototype to 850~900℃ and keep it at that temperature for 20 minutes to obtain the current sensor; S8. Cut the current sensor, plate the terminal electrodes, and perform appearance inspection to obtain the finished current sensor.

6. The method for fabricating an integrated current sensor based on magnetic ceramic materials according to claim 5, characterized in that: In S1, the magnetic ceramic powder is nickel-zinc ferrite, the organic binder is polyvinyl butyral, and the solvent is butyl carbitol, and they are mixed by ball milling.

7. The method for fabricating an integrated current sensor based on magnetic ceramic materials according to claim 5, characterized in that: S2, for aperture <100 For through holes or blind holes, a laser drilling machine is used; for holes with a diameter >100 mm... For through holes, a carbide punch is used for mechanical punching.

8. The method for fabricating an integrated current sensor based on magnetic ceramic materials according to claim 5, characterized in that: The sampling resistor (4) and damping resistor (5) in S3 have a resistivity of 100~150. .

9. The method for fabricating an integrated current sensor based on magnetic ceramic materials according to claim 5, characterized in that: After the S3 uses screen printing to form the corresponding circuit lines (3), sampling resistor (4) and damping resistor (5) in the blind hole, the green ceramic tape needs to be dried with hot air at 80°C for 10 minutes.

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