An integrated co-fired inductor and a preparation method and application thereof

Abstract

The application provides an integrated co-firing inductor and a preparation method and application thereof. The inductor comprises a magnetic core and a conductor penetrating the inside of the magnetic core. Two ends of the conductor are flush with two opposite surfaces of the magnetic core, and two electrodes are correspondingly arranged at the two ends of the conductor. The dimensional accuracy of the magnetic core in the height direction is within + / -0.05mm. The preparation method comprises the following steps: (1) preparing the conductor and pressing the magnetic core with a groove; (2) placing the conductor in the groove of the magnetic core to obtain a combination; (3) placing the combination in a mold cavity, adding magnetic powder for mold pressing to obtain a semi-finished product; (4) performing heat treatment on the semi-finished product, electroplating at the two ends of the conductor after annealing, and obtaining the integrated co-firing inductor. The inductor provided by the application is suitable for three-dimensional integrated circuits. The inductor can be simultaneously attached to two PCBs, and the dimensional accuracy of the inductor in the height direction is improved, thereby meeting the circuit design requirements.

Description

Technical Field

[0001] This invention belongs to the field of inductor manufacturing technology, and relates to an integrated co-fired inductor, and more particularly to an integrated co-fired inductor, its preparation method and application. Background Technology

[0002] Inductors, as one of the three major passive electronic components in electronic product circuit boards, are widely used in various fields such as consumer electronics, communications, industrial equipment, automobiles, new energy, and the Internet of Things. In recent years, with the rapid iteration of domestic communication technologies and the large-scale construction of related industries such as the Internet of Things and smart cities, the Chinese inductor market has grown rapidly.

[0003] To meet increasingly urgent application demands, the development trend of inductors is gradually showing characteristics such as miniaturization, high frequency, and high power, which places higher demands on the reliability and integrated design of surface mount inductors. Surface mount inductors mainly consist of three parts: coil, magnetic core, and electrodes. Among them, the design of the electrodes is a key factor affecting the inductor's solderability, solderability, and integrated design.

[0004] With the development of integrated design technology, 3D integrated circuits require inductors to be mounted on two PCBs simultaneously to meet circuit design requirements. At the same time, this application places higher demands on the dimensional accuracy of the inductors in the height direction.

[0005] CN 112435844A discloses a co-fired inductor and its fabrication method. The fabrication method includes: filling a mold cavity with magnetic powder, embedding at least one wire in the magnetic powder with both ends of the wire extending out of the mold cavity, followed by sequential molding and heat treatment to obtain a magnetic core, and bending and tinning the wire extending out of the magnetic core to obtain the co-fired inductor. However, the electrodes of the inductor are bent from the side to the bottom, with the two electrodes on the same horizontal plane, which can only be mounted on a single PCB board and is not suitable for three-dimensional integrated circuits. Furthermore, the one-time molding process makes it difficult to guarantee the dimensional accuracy in the height direction of the inductor.

[0006] Therefore, how to provide an integrated co-fired inductor suitable for three-dimensional integrated circuits and its fabrication method, so that the inductor can be mounted on two PCBs at the same time, while improving the dimensional accuracy of the inductor in the height direction to meet the circuit design requirements, has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide an integrated co-fired inductor, its preparation method, and its application. The integrated co-fired inductor is particularly suitable for three-dimensional integrated circuits. The inductor can be mounted on two PCBs simultaneously, and the dimensional accuracy in the height direction of the inductor is improved, thus meeting the circuit design requirements.

[0008] To achieve this objective, the present invention employs the following technical solution:

[0009] In a first aspect, the present invention provides an integrated co-fired inductor, the integrated co-fired inductor comprising a magnetic core and a conductor penetrating the interior of the magnetic core.

[0010] The two ends of the conductor are flush with the two surfaces opposite to the magnetic core, and two electrodes are respectively provided at the two ends of the conductor.

[0011] The direction in which the two electrodes are located is taken as the height direction of the magnetic core. The dimensional accuracy of the magnetic core in the height direction is within ±0.05mm, for example, it can be ±0.05mm, ±0.04mm, ±0.03mm, ±0.02mm or ±0.01mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0012] This invention aligns the two ends of the conductor running through the inside of the magnetic core with the two opposing surfaces of the magnetic core, enabling the inductor to be mounted on two PCBs simultaneously. This is particularly suitable for 3D integrated circuits, and the dimensional accuracy of the magnetic core in the height direction is limited to within ±0.05mm, meeting the dimensional accuracy requirements of circuit design.

[0013] Preferably, the material of the magnetic core includes any one or a combination of at least two of iron-based soft magnetic materials, cobalt-based soft magnetic materials, or nickel-based soft magnetic materials. Typical but non-limiting combinations include combinations of iron-based soft magnetic materials and cobalt-based soft magnetic materials, combinations of cobalt-based soft magnetic materials and nickel-based soft magnetic materials, combinations of iron-based soft magnetic materials and nickel-based soft magnetic materials, or combinations of iron-based soft magnetic materials, cobalt-based soft magnetic materials, and nickel-based soft magnetic materials.

[0014] Preferably, the conductor is made of copper.

[0015] Preferably, the shape of the conductor includes any one of the following: straight, spiral, S-shaped, Z-shaped, U-shaped, or W-shaped.

[0016] Preferably, the cross-sectional shape of the conductor includes any one of a rectangle, a circle, or an ellipse.

[0017] In a second aspect, the present invention provides a method for preparing an integral co-fired inductor as described in the first aspect, the method comprising the following steps:

[0018] (1) Prepare a conductor and press out a magnetic core with grooves;

[0019] (2) The conductor is placed in the groove of the magnetic core to obtain the assembly;

[0020] (3) Place the assembly into the mold cavity, add magnetic powder and mold it to obtain a semi-finished product;

[0021] (4) The semi-finished product is heat-treated and annealed, and then electroplated at both ends of the conductor to obtain an integral co-fired inductor.

[0022] The preparation method provided by the present invention places the combination of conductor and magnetic core in a mold cavity, adds magnetic powder and then performs molding. The height and length of the resulting inductor are controlled by the mold cavity size, and the width is the thickness after pressing. This improves the dimensional accuracy of the magnetic core in the height direction and avoids the difficult-to-control change in the height of the magnetic core due to pressing.

[0023] Preferably, the pressing pressure in step (1) is 0.5-3 T / cm. 2 For example, it could be 0.5T / cm 2 0.75T / cm 2 1T / cm 2 1.25T / cm 2 1.5T / cm 2 1.75T / cm 2 2T / cm 2 2.25T / cm 2 2.5T / cm 2 2.75T / cm 2 Or 3T / cm 2 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0024] Preferably, the groove in step (1) includes a bottom surface and two opposite sides, and the length of the groove is the same as the length of the conductor.

[0025] Preferably, the bottom surface dimensions of the assembly in step (3) are adapted to the bottom surface dimensions of the mold cavity.

[0026] In this invention, the bottom surface dimensions of the assembly are adapted to the bottom surface dimensions of the mold cavity, specifically by the bottom surface dimensions of the assembly being slightly smaller than the bottom surface dimensions of the mold cavity, so as to ensure that the assembly can be placed exactly inside the mold cavity.

[0027] Preferably, the magnetic powder in step (3) includes any one or a combination of at least two of iron-based magnetic powder, cobalt-based magnetic powder or nickel-based magnetic powder. Typical but non-limiting combinations include combinations of iron-based magnetic powder and cobalt-based magnetic powder, combinations of cobalt-based magnetic powder and nickel-based magnetic powder, combinations of iron-based magnetic powder and nickel-based magnetic powder, or combinations of iron-based magnetic powder, cobalt-based magnetic powder and nickel-based magnetic powder.

[0028] Preferably, the compression pressure in step (3) is 3-20 T / cm. 2 For example, it could be 3T / cm 2 4T / cm 26T / cm 2 8T / cm 2 10T / cm 2 12T / cm 2 14T / cm 2 16T / cm 2 18T / cm 2 Or 20T / cm 2 However, this does not apply to all values ​​listed; other unlisted values ​​within the same range also apply.

[0029] Preferably, the heat treatment in step (4) includes two temperature gradients, namely a first temperature and a second temperature.

[0030] This invention divides the heat treatment process of the magnetic core into two temperature gradients. The first temperature gradient is the adhesive removal stage, which allows the adhesive to be slowly discharged from the magnetic core. The second temperature gradient is to eliminate the internal stress and crystal defects of the metal powder particles, generate a solid-state phase transition reaction, change the crystal structure of the metal powder particles, and form a new magnetic domain structure inside the metal powder particles, thereby improving the magnetic properties of the metal magnetic powder core.

[0031] Preferably, the first temperature is 300-450℃, for example, it can be 300℃, 320℃, 340℃, 360℃, 380℃, 400℃, 420℃, 440℃ or 450℃, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0032] Preferably, the heating time for the first temperature is 60-180 min, for example, it can be 60 min, 80 min, 100 min, 120 min, 140 min, 160 min or 180 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the holding time at the first temperature is 30-120 min, for example, it can be 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] Preferably, the second temperature is 550-750℃, for example, it can be 550℃, 560℃, 580℃, 600℃, 620℃, 640℃, 660℃, 680℃, 700℃, 720℃, 740℃ or 750℃, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0035] Preferably, the heating time of the second temperature is 60-240 min, for example, it can be 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, 200 min, 220 min or 240 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Preferably, the holding time at the second temperature is 30-120 minutes, for example, it can be 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes or 120 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the annealing cooling time in step (4) is 120-240 min, for example, it can be 120 min, 140 min, 160 min, 180 min, 200 min, 220 min or 240 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, step (4) further includes impregnation, spraying and peeling of the inductor in sequence between annealing and electroplating.

[0039] As a preferred embodiment of the second aspect of the present invention, the preparation method includes the following steps:

[0040] (1) Prepare conductors and use 0.5-3T / cm 2 The pressure is used to press out a grooved magnetic core; the groove includes a bottom surface and two opposite sides, and the length of the groove is the same as the length of the conductor;

[0041] (2) The conductor is placed in the groove of the magnetic core to obtain the assembly;

[0042] (3) Place the assembly into the mold cavity, wherein the bottom dimensions of the assembly are adapted to the bottom dimensions of the mold cavity; add magnetic powder for molding, and press with a pressing pressure of 3-20 T / cm. 2 A semi-finished product is obtained; the magnetic powder includes any one or a combination of at least two of iron-based magnetic powder, cobalt-based magnetic powder, or nickel-based magnetic powder.

[0043] (4) The semi-finished product is heat-treated by first heating it to 300-450℃ within 60-180 min and holding it for 30-120 min, then heating it to 550-750℃ within 60-240 min and holding it for 30-120 min, and finally cooling it down within 120-240 min and then performing impregnation, spraying and peeling in sequence, and electroplating at both ends of the conductor to obtain an integral co-fired inductor.

[0044] Thirdly, the present invention provides an application of the integrated co-fired inductor as described in the first aspect in three-dimensional integrated circuits.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) The present invention makes the two ends of the conductor running through the inside of the magnetic core flush with the two surfaces opposite to the magnetic core, so that the inductor can be mounted on two PCB boards at the same time, which is particularly suitable for three-dimensional integrated circuits. It also limits the dimensional accuracy of the magnetic core in the height direction to within ±0.05mm, which meets the dimensional accuracy requirements of circuit design.

[0047] (2) The preparation method provided by the present invention places the combination of conductor and magnetic core in the mold cavity, adds magnetic powder and then performs molding. The height and length of the resulting inductor are controlled by the size of the mold cavity, and the width is the thickness after pressing. This improves the dimensional accuracy of the magnetic core in the height direction and avoids the difficult-to-control change in the height of the magnetic core due to pressing. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the integrated co-fired inductor structure provided by the present invention;

[0049] Figure 2 This is a flowchart of the integrated co-fired inductor fabrication method provided by the present invention.

[0050] Wherein: 1-Magnetic core; 2-Conductor; 3-Electrode. Detailed Implementation

[0051] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0052] Example 1

[0053] This embodiment provides an integral co-fired inductor and its preparation method, such as Figure 1As shown, the integrated co-fired inductor includes a magnetic core 1 and a conductor 2 that penetrates the interior of the magnetic core 1; the two ends of the conductor 2 are flush with the two opposite surfaces of the magnetic core 1, and two electrodes 3 are respectively provided at the two ends of the conductor 2; the direction in which the two electrodes 3 are located is taken as the height direction of the magnetic core 1, the height of the magnetic core 1 is 3mm, and the dimensional accuracy in the height direction is ±0.03mm.

[0054] Specifically, the magnetic core 1 is made of iron-nickel + iron-silicon-aluminum alloy, and the conductor 2 is made of copper; the conductor 2 is straight in shape and has a rectangular cross-section.

[0055] In this embodiment, the preparation method includes the following steps:

[0056] (1) Prepare conductor 2, and use 1.5T / cm 2 The pressure is used to press out a grooved magnetic core 1; the groove includes a bottom surface and two opposite sides, and the length of the groove is the same as the length of the conductor 2;

[0057] (2) The conductor 2 is placed in the groove of the magnetic core 1 to obtain the assembly;

[0058] (3) The assembly is placed in the mold cavity, the bottom dimensions of the assembly being adapted to the bottom dimensions of the mold cavity. Iron-nickel + iron-silicon-aluminum magnetic powder is added for molding, and the pressing pressure is 12T / cm. 2 To obtain a semi-finished product;

[0059] (4) The semi-finished product is heat-treated by first heating it to 375°C within 120 min and holding it for 75 min, then heating it to 650°C within 150 min and holding it for 75 min, and finally cooling it down within 180 min. Then, it is impregnated, sprayed and stripped in sequence, and electroplated at both ends of the conductor 2 to obtain an integral co-fired inductor.

[0060] Example 2

[0061] This embodiment provides an integral co-fired inductor and its preparation method, such as Figure 1 As shown, the integrated co-fired inductor includes a magnetic core 1 and a conductor 2 that penetrates the interior of the magnetic core 1; the two ends of the conductor 2 are flush with the two opposite surfaces of the magnetic core 1, and two electrodes 3 are respectively provided at the two ends of the conductor 2; the direction in which the two electrodes 3 are located is taken as the height direction of the magnetic core 1, the height of the magnetic core 1 is 3mm, and the dimensional accuracy in the height direction is ±0.03mm.

[0062] Specifically, the magnetic core 1 is made of iron-nickel alloy, and the conductor 2 is made of copper; the conductor 2 is straight in shape and has a rectangular cross-section.

[0063] In this embodiment, the preparation method includes the following steps:

[0064] (1) Prepare conductor 2, and use 0.5T / cm 2 The pressure is used to press out a grooved magnetic core 1; the groove includes a bottom surface and two opposite sides, and the length of the groove is the same as the length of the conductor 2;

[0065] (2) The conductor 2 is placed in the groove of the magnetic core 1 to obtain the assembly;

[0066] (3) The assembly is placed in the mold cavity, the bottom dimensions of the assembly being adapted to the bottom dimensions of the mold cavity. Iron-nickel magnetic powder is added for molding, and the pressing pressure is 3T / cm. 2 To obtain a semi-finished product;

[0067] (4) The semi-finished product is heat-treated by first heating it to 450°C within 180 min and holding it for 30 min, then heating it to 750°C within 240 min and holding it for 30 min, and finally cooling it down within 240 min. Then, it is impregnated, sprayed and stripped in sequence, and electroplated at both ends of the conductor 2 to obtain an integral co-fired inductor.

[0068] Example 3

[0069] This embodiment provides an integral co-fired inductor and its preparation method, such as Figure 1 As shown, the integrated co-fired inductor includes a magnetic core 1 and a conductor 2 that penetrates the interior of the magnetic core 1; the two ends of the conductor 2 are flush with the two opposite surfaces of the magnetic core 1, and two electrodes 3 are respectively provided at the two ends of the conductor 2; the direction in which the two electrodes 3 are located is taken as the height direction of the magnetic core 1, the height of the magnetic core 1 is 3mm, and the dimensional accuracy in the height direction is ±0.03mm.

[0070] Specifically, the magnetic core 1 is made of iron-cobalt alloy, and the conductor 2 is made of copper; the conductor 2 is straight in shape and has a rectangular cross-section.

[0071] In this embodiment, the preparation method includes the following steps:

[0072] (1) Prepare conductor 2, and use 3T / cm 2 The pressure is used to press out a grooved magnetic core 1; the groove includes a bottom surface and two opposite sides, and the length of the groove is the same as the length of the conductor 2;

[0073] (2) The conductor 2 is placed in the groove of the magnetic core 1 to obtain the assembly;

[0074] (3) The assembly is placed in the mold cavity, the bottom dimensions of the assembly being adapted to the bottom dimensions of the mold cavity. Iron-cobalt magnetic powder is added for molding, and the pressing pressure is 20T / cm. 2 To obtain a semi-finished product;

[0075] (4) The semi-finished product is heat-treated by first heating it to 300°C within 60 minutes and holding it for 120 minutes, then heating it to 550°C within 60 minutes and holding it for 120 minutes, and finally cooling it down within 120 minutes. Then, it is impregnated, sprayed and stripped in sequence, and electroplated at both ends of the conductor 2 to obtain an integral co-fired inductor.

[0076] Example 4

[0077] This embodiment provides an integrated co-fired inductor and its preparation method. Except for changing the shape of conductor 2 to a spiral shape and its cross-sectional shape to a circle, the rest of the structure and conditions are the same as in embodiment 1, so they will not be described in detail here.

[0078] Example 5

[0079] This embodiment provides an integrated co-fired inductor and its preparation method. Except for changing the shape of conductor 2 to S-shape and its cross-sectional shape to elliptical, the rest of the structure and conditions are the same as in embodiment 1, so they will not be described in detail here.

[0080] Example 6

[0081] This embodiment provides an integrated co-fired inductor and its preparation method. Except that step (4) is changed to: heat treatment of the semi-finished product, first heating it to 650°C within 270 min and holding it at that temperature for 75 min, then cooling it down within 180 min and then performing impregnation, spraying and peeling in sequence, and electroplating at both ends of the conductor 2 to obtain an integrated co-fired inductor; the remaining steps and conditions are the same as in embodiment 1, so they will not be repeated here.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing an integral co-fired inductor, specifically using the preparation method disclosed in Example 1 of CN112435844A, which will not be described in detail here.

[0084] The performance test results of the integrated co-fired inductors obtained in Examples 1 and 6 and Comparative Example 1 are shown in Table 1.

[0085] Table 1

[0086]

[0087] Where Spec represents the specification; Avg represents the average value; and Std represents the standard deviation. The specific test conditions are as follows: dimensions are measured using digital vernier calipers; inductance measurement conditions are 100kHz, 1.0Vrms, 0Adc; inductance measurement conditions under saturation current are 100kHz, 1.0Vrms, saturation current (e.g., 40Adc, 70Adc); and DCR is measured at 25℃.

[0088] As shown in Table 1, the standard deviation (std) of the height direction of the products in Examples 1 and 6 is 0.01 mm, that is, the dimensional accuracy (±3std) in the height direction is 0.03 mm, both meeting the accuracy requirement within ±0.05 mm. Compared with Example 1, Example 6 has a single-stage heating process, while Example 1 uses a two-stage heating process. Due to the excessively rapid heating during the glue removal process, Example 6 may have the risk of magnetic core bulging or cracking. In Comparative Example 1, the standard deviation (std) of the height direction is 0.04 mm, that is, the dimensional accuracy (±3std) in the height direction is ±0.12 mm, which cannot meet the accuracy requirement of ±0.05 mm. In Comparative Example 1, the height is controlled by the pressing stroke, resulting in poor accuracy, while in Examples 1 and 6, the product height is controlled by the mold cavity size, resulting in high accuracy.

[0089] As can be seen, this invention aligns the two ends of the conductor running through the inside of the magnetic core with the two opposing surfaces of the magnetic core, enabling the inductor to be mounted on two PCBs simultaneously. This is particularly suitable for three-dimensional integrated circuits, and the dimensional accuracy of the magnetic core in the height direction is limited to within ±0.05mm, meeting the dimensional accuracy requirements of circuit design.

[0090] Furthermore, the preparation method provided by the present invention places the combination of conductor and magnetic core in a mold cavity, adds magnetic powder and then performs molding. The height and length of the resulting inductor are controlled by the mold cavity size, and the width is the thickness after pressing. This improves the dimensional accuracy of the magnetic core in the height direction and avoids the difficult-to-control change in the height of the magnetic core due to pressing.

[0091] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing an integrally co-fired inductor, characterized in that, The integrated co-fired inductor includes a magnetic core and a conductor penetrating the interior of the magnetic core. The fabrication method includes the following steps: (1) Prepare a conductor and press out a magnetic core with grooves; (2) The conductor is placed in the groove of the magnetic core to obtain the assembly; (3) Place the assembly into the mold cavity, add magnetic powder and mold it to obtain a semi-finished product; (4) The semi-finished product is heat-treated and annealed, and then electroplated at both ends of the conductor to obtain an integral co-fired inductor; The groove in step (1) includes a bottom surface and two opposite sides, and the length of the groove is the same as the length of the conductor; In step (3), the bottom dimensions of the assembly are adapted to the bottom dimensions of the mold cavity; the two ends of the conductor are flush with the two surfaces opposite to the magnetic core, and two electrodes are respectively provided at the two ends of the conductor; The direction in which the two electrodes are located is taken as the height direction of the magnetic core, and the dimensional accuracy of the magnetic core in the height direction is within ±0.05mm.

2. The preparation method according to claim 1, characterized in that, The magnetic core is made of any one or a combination of at least two of the following: iron-based soft magnetic materials, cobalt-based soft magnetic materials, or nickel-based soft magnetic materials.

3. The preparation method according to claim 1, characterized in that, The conductor is made of copper.

4. The preparation method according to claim 1, characterized in that, The shape of the conductor includes any one of the following: straight, spiral, S-shaped, Z-shaped, U-shaped, or W-shaped.

5. The preparation method according to claim 1, characterized in that, The cross-sectional shape of the conductor includes any one of rectangular, circular, or elliptical shapes.

6. The preparation method according to claim 1, characterized in that, The pressing pressure in step (1) is 0.5-3 T / cm. 2 .

7. The preparation method according to claim 1, characterized in that, The magnetic powder in step (3) includes any one or a combination of at least two of iron-based magnetic powder, cobalt-based magnetic powder, or nickel-based magnetic powder.

8. The preparation method according to claim 1, characterized in that, The pressing pressure for compression molding in step (3) is 3-20 T / cm. 2 .

9. The preparation method according to claim 1, characterized in that, The heat treatment in step (4) includes two temperature gradients, namely a first temperature and a second temperature.

10. The preparation method according to claim 9, characterized in that, The first temperature is 300-450℃.

11. The preparation method according to claim 9, characterized in that, The heating time to the first temperature is 60-180 minutes.

12. The preparation method according to claim 9, characterized in that, The holding time at the first temperature is 30-120 minutes.

13. The preparation method according to claim 9, characterized in that, The second temperature is 550-750℃.

14. The preparation method according to claim 9, characterized in that, The heating time for the second temperature is 60-240 minutes.

15. The preparation method according to claim 9, characterized in that, The holding time at the second temperature is 30-120 minutes.

16. The preparation method according to claim 1, characterized in that, The annealing cooling time in step (4) is 120-240 min.

17. The preparation method according to claim 1, characterized in that, Step (4) includes impregnation, spraying and peeling of the inductor in sequence between annealing and electroplating.

18. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Prepare conductors and use 0.5-3T / cm 2 The pressure is used to press out a grooved magnetic core; the groove includes a bottom surface and two opposite sides, and the length of the groove is the same as the length of the conductor; (2) The conductor is placed in the groove of the magnetic core to obtain the assembly; (3) Place the assembly into the mold cavity, wherein the bottom dimensions of the assembly are adapted to the bottom dimensions of the mold cavity; add magnetic powder for molding, and press with a pressing pressure of 3-20 T / cm. 2 A semi-finished product is obtained; the magnetic powder includes any one or a combination of at least two of iron-based magnetic powder, cobalt-based magnetic powder, or nickel-based magnetic powder. (4) The semi-finished product is heat-treated by first heating it to 300-450℃ within 60-180 min and holding it for 30-120 min, then heating it to 550-750℃ within 60-240 min and holding it for 30-120 min, and finally cooling it down within 120-240 min and then performing impregnation, spraying and peeling in sequence, and electroplating at both ends of the conductor to obtain an integral co-fired inductor.

19. The application of a monolithic co-fired inductor prepared by the preparation method according to any one of claims 1-18 in the field of three-dimensional integrated circuits.

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