Inductance element and preparation method thereof

Abstract

The invention provides an inductance element and a preparation method thereof, the inductance element comprises a magnetic part and a winding embedded in the magnetic part, and the magnetic part comprises metal magnetic powder and first glass powder; the winding is a linear or spiral coil, the number of turns of the coil is not less than 2, an insulating layer is arranged on the surface of the coil, and the insulating layer comprises second glass powder; wherein the softening temperature of the first glass powder is lower than that of the second glass powder. According to the inductance element and the preparation method thereof, the second glass powder is adopted as a coil insulation material, the insulation mode is compatible with a copper-iron co-firing process, a multi-circle copper-iron co-firing inductor can be prepared, and therefore the inductance element with a large inductance value is obtained; the second glass powder is only in a softened state and cannot flow, so that the second glass powder on the surfaces of the coils cannot permeate into gaps of the metal magnetic powder, and the insulation performance between the coils is guaranteed.

Description

Technical Field

[0001] The present application belongs to the technical field of inductor components, and in particular, relates to an inductor component and a preparation method thereof. Background Art

[0002] One-piece molded inductors use metal powder as the magnetic material and are pressed together with the coil. The coil is embedded in the magnetic material and has high saturation resistance, good shielding characteristics, and little magnetic leakage, making it a popular application. In order to meet the increasing demand for power density of electronic products, one-piece molded inductors have also been developing in the direction of miniaturization and power, and continuously improving their anti-saturation ability and high temperature resistance.

[0003] The current one-piece molded inductor has a preparation process that includes: first, fully mixing the granulated magnetic powder with thermoplastic epoxy resin, pressing it into a T-shaped core column without heating, then putting the flat copper coil coated with insulating paint on the surface on the T-shaped core column, and bending out the pins, then putting the assembled coil into the mold cavity, filling the powder again, and pressing it under heating conditions. The powder filled again is tightly combined with the T-shaped core column under the combined action of heating and pressure, and then the lead end is prepared by insulation coating, laser stripping, and electroplating. The inductor made by this process has a disadvantage: the temperature it withstands depends on the tolerance temperature of the resin bonding the magnetic powder. When the temperature is higher than the tolerance temperature of the resin, the resin will age and decompose, causing the inductor to lose strength. Generally, resins with good bonding properties cannot work for a long time at about 200°C, which determines the upper power limit of the one-piece molded inductor using this production process. In order to increase the upper power limit of the inductor, an inductor prepared by a copper-iron co-firing process is proposed. The inductor produced by this process needs to be sintered. After sintering, the bonding between the powders depends on the inorganic grain boundary phase. In this way, the inductor can theoretically work at close to 300°C, which is much higher than 200°C. However, the disadvantage of the inductor produced by this process is that since it needs to be sintered after forming, the sintering temperature is above 700°C, and the insulation layer of the copper wire will be destroyed. The inductor can only adopt a single-layer coil design, resulting in the inability to obtain a high inductance value.

[0004] In summary, the current preparation process of inductors requires sintering, and the high sintering temperature causes the insulation layer between the coils to be destroyed. Summary of the invention

[0005] In view of this, the present application provides an inductor element and a method for preparing the same, so as to solve the technical problem that the insulating layer between the multi-layer coils is easily damaged during the copper-iron co-firing process.

[0006] In a first aspect, the present application provides an inductor element, the inductor comprising a magnetic portion and a winding buried in the magnetic portion, the magnetic portion comprising metal magnetic powder and a first glass powder;

[0007] The winding is a linear or spiral coil, wherein the number of turns of the coil is not less than 2, and an insulating layer is provided on the surface of the coil, and the insulating layer includes a second glass powder;

[0008] Wherein, the softening temperature of the first glass powder is lower than the softening temperature of the second glass powder.

[0009] In some embodiments, the softening temperature of the second glass frit is 0-200° C. higher than the softening temperature of the second glass frit.

[0010] In some embodiments, the softening temperature of the first glass powder is 500°C to 600°C, and the softening temperature of the second glass powder is 600°C to 700°C.

[0011] In some embodiments, the metal magnetic powder includes at least one of iron-based amorphous powder, iron-nickel alloy powder, and carbonyl iron powder.

[0012] In some embodiments, the metal magnetic powder is spherical powder or quasi-spherical powder, and the surface of the metal magnetic powder is subjected to insulation treatment.

[0013] In some embodiments, the first glass powder and the second glass powder include at least one of soda-lime glass powder, aluminum borosilicate glass powder, bismuth borosilicate glass powder, zinc borosilicate glass powder, and calcium borosilicate glass powder.

[0014] In some embodiments, the metal magnetic powder is an iron-based amorphous powder, wherein the preparation of the iron-based amorphous powder comprises the following steps:

[0015] Providing an iron-based amorphous strip with a thickness of 20 μm to 30 μm;

[0016] The strip is crushed and ground into fine powder;

[0017] The fine powder is sieved to obtain the iron-based amorphous powder with a D50 between 13 μm and 17 μm.

[0018] In a second aspect, the present application provides a method for preparing an inductor element, comprising the following steps:

[0019] preparing a magnetic part;

[0020] Winding at least two groups of coils on the magnetic part to form a winding;

[0021] preparing an insulating layer on the surface of the coil;

[0022] The inductor element is obtained by sintering using a copper-iron co-firing process.

[0023] In some embodiments, the preparation of the magnetic portion comprises the following steps:

[0024] Providing metal magnetic powder, first glass powder, organic solvent and adhesive;

[0025] First, the metal magnetic powder and part of the organic solvent are mixed to obtain a first mixture, then the binder is mixed with part of the organic solvent to form a glue solution, and the glue solution is mixed with the first mixture to obtain a second mixture;

[0026] Add the first glass powder to the second mixture, mix evenly, and continue stirring and kneading until a loose soil block is obtained, and then granulate to obtain magnetic particles;

[0027] The magnetic particles are pressed to obtain the magnetic portion.

[0028] In some embodiments, before adding the first glass powder to the second mixture, the method includes:

[0029] The second mixture is continuously stirred and kneaded to allow the organic solvent to evaporate continuously until the second mixture begins to form large wet soil lumps.

[0030] In some embodiments, in the step of adding the first glass powder to the second mixture and mixing, the mixing includes:

[0031] Continue stirring and kneading for 0.5 h to 1 h until no white powder can be seen with the naked eye.

[0032] In some embodiments, the step of preparing an insulating layer on the surface of the coil comprises the following steps:

[0033] Providing the following raw materials in parts by weight: 100 parts of a second glass powder, 5 to 10 parts of polyvinyl butyral, 80 to 100 parts of an organic solvent, and 1 to 3 parts of a dispersant, and mixing all of the raw materials to obtain a flowable slurry;

[0034] Pre-treating the surface of the coil except for the lead-out end portion;

[0035] The surface of the pretreated coil except the lead-out end is immersed in the slurry, and after drying, it is baked to obtain an insulating layer covering the coil except the lead-out end.

[0036] In some embodiments, in the copper-iron co-firing process for sintering, the conditions of the copper-iron co-firing process include:

[0037] The sintering time is 1h~2h;

[0038] The peak temperature is 450℃~550℃;

[0039] The insulation period is 10min to 20min.

[0040] The inductor element provided in the embodiment of the present application adopts the second glass powder as the material for coil insulation. This insulation method is compatible with the copper-iron co-firing process, and a multi-turn copper-iron co-firing inductor can be prepared to obtain an inductor element with a large inductance value. The softening temperature of the second glass powder of the coil is higher than the softening temperature of the first glass powder used as a sintering aid in the magnetic part. Its function is to infiltrate and enhance the bonding of the two glasses (the first glass powder and the second glass powder) during high-temperature sintering. In this way, during the co-firing process after molding, the first glass powder mixed in the metal magnetic powder begins to flow to promote sintering, and can also infiltrate and bond with the insulating layer formed by the second glass powder on the surface of the coil. However, since the softening temperature of the second glass powder on the surface of the coil is higher, the second glass powder is only in a softened state and cannot flow. In this way, the second glass powder on the surface of the coil will not penetrate into the gap of the metal magnetic powder, thereby ensuring the insulation performance between the multi-layer coils. The first glass powder mixed in the metal magnetic powder is converted into a flow in the liquid phase during sintering to play a role in sintering, and after cooling, it solidifies and provides strength, thereby improving the mechanical strength of the inductor element.

[0041] The method for preparing the inductor element provided in the embodiment of the present application has the following advantages:

[0042] Integrated manufacturing: The coil and the magnetic part (ferrite core) are sintered simultaneously at high temperature to form a whole, reducing the assembly steps. High temperature sintering: High temperature sintering technology is used to ensure good bonding between the copper coil and the magnetic core. The copper-iron co-firing process can improve the reliability of the inductor because the one-piece molding reduces the risk of failure due to poor welding or mechanical connection. High efficiency: The copper-iron co-firing process can improve the efficiency of the inductor because the close bonding between the copper coil and the magnetic core reduces energy loss. Stable performance: Due to the good bonding between the copper coil and the magnetic core, the performance of the inductor is more stable at different temperatures and frequencies. The one-piece molded inductor prepared by this method in the embodiment of the present application can withstand higher temperatures and obtain a larger inductance value than the one-piece molded inductor of an ordinary bonded magnet. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 It is a schematic diagram of a process of preparing an inductor element provided in an embodiment of the present application;

[0045] Figure 2 is a schematic flow chart of step S10 in the method for preparing an inductor element provided in an embodiment of the present application;

[0046] Figure 3 is a schematic flow chart of step S30 in the method for preparing an inductor element provided in an embodiment of the present application;

[0047] Figure 4 It is a sintering curve diagram in step S40 in the method for preparing an inductor element provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0049] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0050] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0051] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0052] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0053] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways. "Multiple" means two or more.

[0054] In order to meet the application of higher power density, a copper-iron co-fired inductor has appeared on the market. It is used in power modules that match GPU (Graphics Processing Unit) power supply. Since the power required by GPU is several times greater than that of ordinary CPU (Central Processing Unit), the ambient temperature and the required power are also greater, which makes the operating temperature of the inductor in the power module higher. In order to allow the inductor to withstand higher operating temperatures, a company has proposed a technical solution of copper-iron co-firing. Its structure is a flat copper wire passing through a cubic magnetic material. The difference between the preparation process of this inductor and the existing conventional inductor is that its material is not only cured by resin after molding, but also sintered. The bonding between the powders after sintering depends on the inorganic grain boundary phase, so that the inductor can theoretically work at close to 300°C.

[0055] The inductor made by the above process has a disadvantage that, since it needs to be sintered after forming, the sintering temperature is above 700°C, and the insulation layer of the copper wire will be destroyed. Therefore, the inductor design can only adopt a single-layer coil design, which makes it difficult to obtain a higher inductance value. That is, when the above method is used to prepare a high-inductance inductor component with multi-layer coils, the insulation layer between the multi-layer coils is easily destroyed during the sintering process.

[0056] In summary, the inductor element and preparation method provided in the embodiments of the present application are aimed at solving the insulation problem between multi-layer coils under the copper-iron co-firing process. Specifically, a low-melting-point second glass powder is used as the material of the insulating layer. This insulation method is compatible with the copper-iron co-firing inductor process, and multi-turn copper-iron co-fired inductors can be prepared to obtain a large inductance value. Since the softening temperature of the second glass powder on the surface of the coil is higher, the second glass powder is only in a softened state and cannot flow. In this way, the second glass powder on the surface of the coil will not penetrate into the gap between the metal magnetic powder, thereby ensuring the insulation performance between the multi-layer coils.

[0057] An embodiment of the present application provides an inductor element, comprising a magnetic portion and a winding, wherein the winding is embedded in the magnetic portion;

[0058] The magnetic part includes metal magnetic powder and first glass powder;

[0059] The winding is a linear or spiral coil, the number of turns of the coil is not less than 2, and the surface of the coil is provided with an insulating layer, and the insulating layer includes a second glass powder;

[0060] The softening temperature of the first glass powder is lower than the softening temperature of the second glass powder.

[0061] The inductor element provided in the embodiment of the present application adopts the second glass powder as the material for coil insulation. This insulation method is compatible with the copper-iron co-firing process, and a multi-turn copper-iron co-firing inductor can be prepared to obtain an inductor element with a large inductance value. The softening temperature of the second glass powder of the coil is higher than the softening temperature of the first glass powder used as a sintering aid in the magnetic part. Its function is to infiltrate and enhance the bonding of the two glasses (the first glass powder and the second glass powder) during high-temperature sintering. In this way, during the co-firing process after molding, the first glass powder mixed in the metal magnetic powder begins to flow to promote sintering, and can also infiltrate and bond with the insulating layer formed by the second glass powder on the surface of the coil. However, since the softening temperature of the second glass powder on the surface of the coil is higher, the second glass powder is only in a softened state and cannot flow. In this way, the second glass powder on the surface of the coil will not penetrate into the gap of the metal magnetic powder, thereby ensuring the insulation performance between the multi-layer coils. The first glass powder mixed in the metal magnetic powder is converted into a flow in the liquid phase during sintering to play a role in sintering, and after cooling, it solidifies and provides strength, thereby improving the mechanical strength of the inductor element.

[0062] In applications, an inductor is a basic electronic component used to store magnetic field energy. It usually consists of one or more windings (coils) that can be wrapped around a magnetic core (such as a ferrite core) or hollow. Inductors are widely used in electronic circuits, such as power supply filtering, signal tuning, impedance matching, etc. The magnetic part is the core (ferrite core), and the winding is the copper wire (enameled wire) wound around the core.

[0063] The winding is a linear or spiral coil. In the embodiment of the present application, the winding method of the coil is different. The linear and spiral shapes refer to the shape of the cross-sectional view of the coil. The number of turns of the coil is not less than 2, that is, in the embodiment of the present application, the number of turns of the coil is 2, 3, 4, 5, 6, 7, ..., and other integers greater than or equal to 2. In application, the number of turns of the coil has a direct impact on the performance of the inductor. The more turns of the coil, the greater the inductance (L) of the inductor, but it also affects other key parameters such as direct current resistance (DCR), quality factor (Q value) and self-resonant frequency (SRF). The number of turns of the coil needs to be determined according to the specific application requirements. For example, in applications requiring high inductance and low loss, you may choose to increase the number of turns of the coil. In applications requiring high frequency response and small size, you may tend to reduce the number of turns.

[0064] The insulation layer on the coil is an important part in the manufacture of inductor components. It is used to ensure the safe operation of the inductor and improve its performance. The role of the insulation layer includes but is not limited to preventing short circuits, improving mechanical stability, and reducing energy loss. The functions of the insulation layer include:

[0065] Prevent short circuits: The insulation layer can prevent contact between coils and avoid the occurrence of short circuits. Improve mechanical stability: The insulation layer can increase the mechanical strength of the coil and reduce damage caused by vibration or external force. Reduce energy loss: A good insulation layer can help reduce eddy current loss and hysteresis loss and improve the efficiency of the inductor. Improve temperature resistance: The insulation layer can improve the temperature resistance of the inductor so that it can still work normally in a high temperature environment. Improve heat dissipation: Some insulating materials have good thermal conductivity, which can help the inductor dissipate heat better. Increase durability: The insulation layer can protect the coil from environmental factors (such as humidity, corrosive gases, etc.) and extend the service life of the inductor.

[0066] In application, the insulating layer on the coil does not cover the lead-out end of the coil, that is, except for the lead-out end, the rest of the coil is covered with an insulating layer, and the lead-out end is used to connect current.

[0067] In applications, the insulation layer takes the following shapes. Enameled wire: This is the most common form of insulation, with a layer of insulating paint coated on the surface of the wire, usually used in low-frequency applications. Film insulation: Uses materials such as polyester film and polyimide film as the insulation layer, suitable for high-frequency and high-temperature applications. Polytetrafluoroethylene (PTFE): Has excellent insulation properties and temperature resistance, suitable for extreme environments. Polyvinyl butyral (PVB): Although not common in inductor manufacturing, it can be used as an insulating material or adhesive. Silane coupling agent: Used to improve the adhesion between the insulation layer and the coil, improving insulation performance and stability.

[0068] In the embodiment of the present application, the insulating layer on the coil includes a second glass powder, and a low-melting-point glass is used as the insulating material of the coil. This insulation method is compatible with the copper-iron co-firing process, and a multi-turn copper-iron co-firing inductor can be prepared to obtain a large inductance value. The softening temperature of the low-melting-point second glass powder of the coil is higher than that of the first glass powder used as a sintering aid in the metal magnetic powder. The effect is that the two glasses are infiltrated and enhanced during sintering, but the second glass powder on the surface of the coil will not immerse in the magnetic powder, causing the insulation layer of the coil to fail. This is because the softening temperature of the second glass powder on the surface of the coil is higher, so the second glass powder is only in a softened state and cannot flow, so that the second glass powder on the surface of the coil will not penetrate into the gap between the metal magnetic powder, thereby ensuring the insulation performance between the multi-layer coils.

[0069] In some embodiments, the first glass powder and the second glass powder include at least one of soda-lime glass powder, aluminum borosilicate glass powder, bismuth borosilicate glass powder, zinc borosilicate glass powder, and calcium borosilicate glass powder. In a specific embodiment, the first glass powder includes at least one of soda-lime glass powder, aluminum borosilicate glass powder, bismuth borosilicate glass powder, zinc borosilicate glass powder, and calcium borosilicate glass powder; the second glass powder includes at least one of soda-lime glass powder, aluminum borosilicate glass powder, bismuth borosilicate glass powder, zinc borosilicate glass powder, and calcium borosilicate glass powder.

[0070] The difference between softening temperature and melting point is that softening temperature is the temperature at which a material starts to become soft or flow when heated. This temperature point is not a clear transition point, but a gradual process. Softening temperature is often used to describe the behavior of polymers, composite materials or certain amorphous solid materials. Melting point is the temperature point when a crystalline substance changes from solid to liquid. This is a clear phase change process, usually accompanied by the absorption of heat. Softening temperature is a temperature range rather than a single temperature point. Melting point is a clear temperature point, not a range.

[0071] Therefore, when the first glass powder and the second glass powder are single substances, the softening temperature is also the melting point. For example, when the first glass powder contains only aluminoborosilicate glass powder and the second glass powder contains only calcium borosilicate glass powder, the softening temperature of the first glass powder is lower than the softening temperature of the second glass powder, which should be understood as the melting point of the first glass powder is lower than the melting point of the second glass powder. Generally speaking, the first glass powder and the second glass powder are a mixture, so they are usually described by the softening temperature, and the softening process of the glass is reversible. After being softened by heat, it will return to its original solid state after cooling.

[0072] In some embodiments, the softening temperature of the second glass powder is 0 to 200°C higher than the softening temperature of the second glass powder. By limiting the softening temperature difference between the second glass powder and the first glass powder, it is to ensure that in the copper-iron co-firing process, the second glass powder as the insulating layer material will not be immersed in the magnetic part and cause the insulating layer to be damaged. In application, the softening temperature of the second glass powder is 10°C, 20°C, 50°C, 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, etc., which is any value within the range of 0 to 200°C, higher than the softening temperature of the second glass powder.

[0073] Furthermore, in some embodiments, the softening temperature of the first glass powder is 500°C to 600°C, and the softening temperature of the second glass powder is 600°C to 700°C. In this way, the softening temperature of the first glass powder is 100°C lower than that of the second glass powder. In this way, during the co-firing process after the inductor element is formed, the first glass powder mixed in the metal magnetic powder starts to flow to promote sintering, and can also be infiltrated and combined with the second glass powder on the surface of the coil. However, the second glass powder on the surface of the coil is only in a softened state and cannot flow because of its higher softening temperature (100°C higher). In this way, the second glass powder on the surface of the coil will not penetrate into the gap between the metal magnetic powder, ensuring the insulation performance between the multi-layer coils. In addition, the softening temperature of the first glass powder is lower than the softening temperature of ordinary glass, and is selected between 500°C and 700°C, preferably between 500°C and 600°C, because the sintering temperature range of the inductor is between 700°C and 900°C, and the softening temperature must be lower than the sintering temperature to ensure fluidity. After the glass softens, it can use the tension of the liquid to cover the surface of the copper wire and solidify after cooling to play an insulating role. In this way, the glass morphology will not change below 500°C.

[0074] In some embodiments, the metal magnetic powder is a spherical powder or a quasi-spherical powder, and the surface of the metal magnetic powder is subjected to insulation treatment. Furthermore, the insulation treatment includes treatment with SiO2 or Al2O3. Spherical or quasi-spherical particles can provide better fluidity, which is conducive to easier filling and compaction during the manufacturing process. Amorphous structure: The amorphous structure has lower magnetic anisotropy than crystalline materials, and can provide higher magnetic permeability and lower loss. Insulating layer: The SiO2 or Al2O3 insulating layer on the surface can improve the insulation between particles, reduce eddy current losses, and thus improve the high-frequency performance of the material.

[0075] In some embodiments, the metal magnetic powder includes at least one of iron-based amorphous powder, iron-nickel alloy powder, and carbonyl iron powder. Metal magnetic powder is a material used to manufacture high-performance magnetic components, which has excellent magnetic properties and physical properties. Metal magnetic powder is generally used to manufacture electronic components such as magnetic cores, inductors, transformers, etc., especially in applications requiring high saturation flux density, low loss and a wide operating temperature range. Types of metal magnetic powder include but are not limited to iron powder, iron silicon aluminum alloy (FeSiAl), iron nickel molybdenum alloy (FeNiMo), iron nickel molybdenum cobalt alloy (FeNiMoCo), etc.

[0076] In some embodiments, the metal magnetic powder is an iron-based amorphous powder, wherein the preparation of the iron-based amorphous powder comprises the following steps:

[0077] Providing an iron-based amorphous strip with a thickness of 20 μm to 30 μm;

[0078] Crushing the strip and grinding it into fine powder;

[0079] The fine powder is sieved to obtain an iron-based amorphous powder with a D50 between 13 μm and 17 μm.

[0080] The amorphous powder crushed by strip is very different from the ordinary spherical amorphous powder. The amorphous phase of the amorphous strip is purer, and the proportion of the amorphous phase is larger after sintering, which makes the material have better insulation properties. In addition, the surface of the amorphous spherical powder prepared by the crushing of strip amorphous and the air flow mill is not smooth, and the strength of the green body after forming is higher, which is conducive to reducing the poor crushing and improving the qualified rate of the inductor processing process. In the application, the preparation method of iron-based amorphous powder is to take an iron-based amorphous strip with a thickness of 20 to 30 μm, crush it, and use the air flow mill under nitrogen protection to grind the iron-based amorphous fragments into fine powder, and control the particle size distribution to D50 = 13 to 17 μm, and remove the coarse particles through a 500 mesh sieve.

[0081] The present application embodiment provides a method for preparing an inductor element, such as Figures 1 to 4 As shown, the following steps are included:

[0082] S10, preparing a magnetic part;

[0083] S20, winding at least two groups of coils on the magnetic part to form a winding;

[0084] S30, preparing an insulating layer on the surface of the coil;

[0085] S40, sintering is performed using a copper-iron co-firing process to obtain an inductor component.

[0086] The preparation method of the inductor element provided in the embodiment of the present application, the coil and the magnetic part (ferrite core) are sintered at high temperature at the same time to form a whole, which reduces the assembly steps and adopts high temperature sintering technology to ensure good bonding between the copper coil and the magnetic core. The copper-iron co-firing process can improve the reliability of the inductor because the one-piece molding reduces the risk of failure due to poor welding or mechanical connection. The copper-iron co-firing process can improve the efficiency of the inductor because the close bonding between the copper coil and the magnetic core reduces energy loss. Due to the good bonding between the copper coil and the magnetic core, the performance of the inductor at different temperatures and frequencies is more stable.

[0087] In some embodiments, in step S10, preparing the magnetic portion includes the following steps:

[0088] S11, providing metal magnetic powder, a first glass powder, an organic solvent and a binder;

[0089] S12, firstly mixing the metal magnetic powder and part of the organic solvent to obtain a first mixture, then mixing the binder and part of the organic solvent to form a glue solution, and mixing the glue solution with the first mixture to obtain a second mixture;

[0090] S13, adding the first glass powder to the second mixture, mixing, and continuously stirring and kneading until a loose soil block is obtained, and then granulating to obtain magnetic particles;

[0091] S14, pressing the magnetic particles to obtain a magnetic portion.

[0092] In the embodiment of the present application, the first glass powder with a low softening temperature is used as a sintering aid and a binder, and is mixed in the metal magnetic powder. During sintering, the first glass powder is converted into a mobile phase to play a role in sintering, and after cooling, it solidifies and provides strength. The inductor element obtained in this way has a higher mechanical strength.

[0093] In step S11, the metal magnetic powder is selected from at least one of spherical iron-based amorphous powder, iron-nickel alloy powder, and carbonyl iron powder, the surface of which has been treated with SiO2 insulation, the organic solvent includes but is not limited to anhydrous ethanol, acetone, etc., and the binder includes one of epoxy resin, polyvinyl butyral, or polyethylene glycol. The organic solvent plays a role in dispersing the mixed metal magnetic powder.

[0094] In step S12, the metal magnetic powder and the organic solvent (anhydrous ethanol or acetone) accounting for 10 to 15 wt% of the weight of the metal magnetic powder are fully mixed with a kneader for 0.5 to 1 hour to form a thin slurry. The binder and the organic solvent (anhydrous ethanol or acetone) of the same mass as the binder are mixed and stirred to form a uniform glue solution, which is then poured into the uniformly mixed thin slurry and stirred for 0.5 to 1 hour to make it uniform, thereby obtaining a second mixture.

[0095] After step S12 and before step S13, the second mixture is continuously stirred and kneaded to allow the organic solvent to evaporate continuously until the second mixture begins to hang on the paddle to form large wet lumps. When the powder slurry begins to hang on the stirring paddle and form large wet lumps, the low softening point glass powder is uniformly added to improve the mechanical strength, density and stability of the composite material by utilizing the bonding effect and low softening point characteristics of the glass powder without affecting the uniformity of the mixture.

[0096] In step S13, the first glass powder is added to the second mixture for mixing, and the mixing includes:

[0097] Continue stirring and kneading for 0.5 to 1 hour until the white powder cannot be seen with the naked eye. Ensure that the first glass powder and the second mixture are fully mixed so that the first glass powder with a low softening point can form a continuous bonding network during the curing process, thereby improving the mechanical strength of the composite material. The bonding effect of the glass powder can reduce the pores inside the material, improve the density of the material, and thus improve its stability and reliability. In the application, after step S13, it also includes: placing in a constant temperature drying oven and baking at about 50 to 60°C for 1 to 2 hours. Thereby obtaining metal magnetic particles, which are convenient for subsequent pressing and molding.

[0098] In step S30, an insulating layer is prepared on the surface of the coil, including the following steps:

[0099] S31, providing the following raw materials in parts by weight: 100 parts of a second glass powder, 5 to 10 parts of polyvinyl butyral, 80 to 100 parts of an organic solvent, and 1 to 3 parts of a dispersant, and mixing all the raw materials to obtain a flowable slurry;

[0100] S32, pre-treating the surface of the coil except the lead-out end;

[0101] S33, immersing the pre-treated surface of the coil except the lead-out end into the slurry, drying it, and then baking it to obtain an insulating layer covering the coil except the lead-out end.

[0102] The preparation method of the inductor element provided in the embodiment of the present application, wherein an insulating layer is prepared on the coil, and compared with the conventional insulating layer material selection, a second glass powder is added in the embodiment of the present application. By using the second glass powder having a higher softening temperature than the first glass powder, the second glass powder and the first glass powder are infiltrated and increased in bonding during high-temperature sintering. However, since the second glass powder has a high softening temperature and does not flow, it will not be immersed in the metal magnetic powder, thereby ensuring that the insulating layer of the coil is intact.

[0103] In step S31, the softening temperature of the second glass powder is 600-700°C. Since the sintering temperature range of the inductor is 700-900°C, the softening temperature of the second glass powder should be lower than the sintering temperature to ensure fluidity. After the glass softens, it can cover the surface of the coil by the tension of the liquid and solidify after cooling to play an insulating role. In this way, the glass shape will not change below 500°C; polyvinyl butyral plays the role of an adhesive to make the slurry have a certain viscosity so that it can be hung on the surface of the coil; the organic solvent is responsible for dissolving and dispersing the powder; BYK110 is a commonly used inorganic powder dispersant; the role of the silane coupling agent is to enhance the bonding between the second glass powder and the copper wire.

[0104] In step S32, the surface of the coil except the lead-out end is pretreated, including immersing the surface of the coil except the lead-out end in a silane coupling agent, clamping the lead-out end and hanging it to dry until there is no obvious liquid, in order to enhance the bonding between the second glass powder and the coil.

[0105] In step S40, the copper-iron co-firing process includes: after the inductor is formed, the entire inductor is placed in a bell furnace, evacuated to 10-3 MPa, filled with nitrogen or argon protection, and sintering is started. The sintering curve (such as Figure 4 As shown in the figure, the temperature starts from room temperature, rises to 900°C at 5°C / min, is kept at this temperature for 2 hours, and then the temperature is automatically lowered to below 50°C and the furnace door is opened; at this time, the internal copper electrodes of the inductor and the magnetic parts wrapped by the electrodes are processed together at high temperature under a protective atmosphere, and finally the inductor element of the embodiment of the present application is obtained.

[0106] In application, the conditions of copper-iron co-firing process include:

[0107] The sintering time is 1 to 2 hours;

[0108] The peak temperature is 450-550°C;

[0109] The insulation section is 10 to 20 minutes. The sintering time is 1 to 2 hours to ensure that the materials are fully sintered and form a good bond. Too short a sintering time may result in insufficient material bonding, while too long a sintering time may result in excessive sintering of the materials, affecting performance. The peak temperature is 450 to 550°C. Within this temperature range, the copper coil and magnetic powder can be well sintered to form a stable structure. Too low a peak temperature may result in insufficient sintering, while too high a peak temperature may cause material deformation or performance degradation. The insulation section is 10 to 20 minutes. The purpose is to maintain a high temperature for a period of time after reaching the peak temperature to ensure that the materials react and bond fully at high temperature. Too short an insulation time may not be enough for the materials to be fully sintered, while too long an insulation time may result in unnecessary energy consumption.

[0110] The application also includes surface spraying of inductor components and paint stripping and electroplating of lead ends.

[0111] Examples and Comparative Examples

[0112] Examples 1 to 3 are prepared by the inductor preparation method provided in the embodiments of the present application to obtain inductor components of different sizes. Comparative Examples 1 to 3 are prepared by the inductor components using the existing integrated molding process to obtain inductor components of different sizes.

[0113] Examples 4 to 6 are prepared by the inductor preparation method provided in the examples of the present application. Comparative Examples 4 to 6 are basically the same as Example 4, except for the type of amorphous powder, as shown in Table 2.

[0114] Performance Testing

[0115] The inductance values ​​of Examples 1 to 3 and Comparative Examples 1 to 3 were measured and the temperature rise current (A) was tested. Please see Table 1 for specific results.

[0116] The bending strength of the blanks of Examples 4 to 6 and Comparative Examples 4 to 6 was tested, and the specific results are shown in Table 2.

[0117] Table 1 Test results of inductance measurement and temperature rise current (A) of Examples 1 to 3 and Comparative Examples 1 to 3

[0118]

[0119] Table 2 Test results of the bending strength of the blanks in Examples 4 to 6 and Comparative Examples 4 to 6

[0120]

[0121] It can be seen from Table 1 and Table 2 that the inductance value of the inductor element provided in the embodiment of the present application is much higher than that of the inductor prepared by the existing process. Moreover, the strength of the embodiment of the present application using the band-shaped crushed air flow milled iron-based amorphous powder is significantly higher than that of the comparative example using the spherical atomized alloy powder.

[0122] The inductor element and preparation method provided in the embodiments of the present application use an amorphous material which is a spherical or spherical powder of banded amorphous after air flow grinding. Compared with the green body formed by atomized spherical powder, this powder has greater strength and reduces breakage. In addition, after sintering, the proportion of amorphous phase is greater, the product loss is lower, the heat is less, and the product temperature rise rated current is higher. Low-melting-point glass (second glass powder) is used as the material of the coil insulation layer. This insulation method is compatible with the copper-iron co-fired inductor process, and multiple turns of copper-iron co-fired inductor can be prepared, so that a large inductance value can be obtained. The softening temperature of the second glass component on the surface of the coil is higher than the softening temperature of the first glass powder used as a sintering aid in the metal magnetic powder. The effect is that the two glass powders are infiltrated and enhanced during sintering, but the second glass powder on the surface of the coil will not be immersed in the gap of the metal magnetic powder, thereby avoiding damage and failure of the insulation layer on the surface of the coil.

[0123] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0124] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. An inductor element, characterized in that: The inductor comprises a magnetic part and a winding buried in the magnetic part, wherein the magnetic part comprises metal magnetic powder and a first glass powder; The winding is a linear or spiral coil, wherein the number of turns of the coil is not less than 2, and an insulating layer is provided on the surface of the coil, and the insulating layer includes a second glass powder; Wherein, the softening temperature of the first glass powder is lower than the softening temperature of the second glass powder.

2. The inductor element according to claim 1, wherein: The softening temperature of the second glass frit is 0 to 200° C. higher than the softening temperature of the second glass frit.

3. The inductor element according to claim 2, wherein: The softening temperature of the first glass powder is 500°C to 600°C, and the softening temperature of the second glass powder is 600°C to 700°C.

4. The inductor element according to claim 1, wherein: The metal magnetic powder includes at least one of iron-based amorphous powder, iron-nickel alloy powder and carbonyl iron powder; And / or, the metal magnetic powder is spherical powder or quasi-spherical powder, and the surface of the metal magnetic powder is subjected to insulation treatment; And / or, the first glass powder and the second glass powder include at least one of soda-lime glass powder, aluminum borosilicate glass powder, bismuth borosilicate glass powder, zinc borosilicate glass powder, and calcium borosilicate glass powder.

5. The inductor element according to claim 4, characterized in that The metal magnetic powder is an iron-based amorphous powder, wherein the preparation of the iron-based amorphous powder comprises the following steps: Providing an iron-based amorphous strip with a thickness of 20 μm to 30 μm; The strip is crushed and ground into fine powder; The fine powder is sieved to obtain the iron-based amorphous powder with a D50 between 13 μm and 17 μm.

6. A method for preparing an inductor element, characterized in that: The following steps are involved: preparing a magnetic part; Winding at least two groups of coils on the magnetic part to form a winding; preparing an insulating layer on the surface of the coil; The inductor element is obtained by sintering using a copper-iron co-firing process.

7. The preparation method according to claim 6, characterized in that: The preparation of the magnetic part comprises the following steps: Providing metal magnetic powder, first glass powder, organic solvent and adhesive; First, the metal magnetic powder and part of the organic solvent are mixed to obtain a first mixture, then the binder is mixed with part of the organic solvent to form a glue solution, and the glue solution is mixed with the first mixture to obtain a second mixture; Add the first glass powder to the second mixture, mix evenly, and continue stirring and kneading until a loose soil block is obtained, and then granulate to obtain magnetic particles; The magnetic particles are pressed to obtain the magnetic portion.

8. The preparation method according to claim 7, characterized in that: Before adding the first glass powder to the second mixture, the method comprises: The second mixture is continuously stirred and kneaded to allow the organic solvent to evaporate continuously until the second mixture begins to form large wet soil blocks; And / or, in the step of adding the first glass powder to the second mixture and mixing, the mixing includes: Continue stirring and kneading for 0.5 h to 1 h until no white powder can be seen with the naked eye.

9. The preparation method according to claim 6, characterized in that: The step of preparing an insulating layer on the surface of the coil comprises the following steps: Providing the following raw materials in parts by weight: 100 parts of a second glass powder, 5 to 10 parts of polyvinyl butyral, 80 to 100 parts of an organic solvent, and 1 to 3 parts of a dispersant, and mixing all of the raw materials to obtain a flowable slurry; Pre-treating the surface of the coil except for the lead-out end portion; The surface of the pretreated coil except the lead-out end is immersed in the slurry, and after drying, it is baked to obtain an insulating layer covering the coil except the lead-out end.

10. The preparation method according to any one of claims 6 to 9, characterized in that: In the copper-iron co-firing process for sintering, the conditions of the copper-iron co-firing process include: The sintering time is 1h~2h; The peak temperature is 450℃~550℃; The insulation period is 10min to 20min.

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