A high-reliability glue-coated inductor and its preparation method

Abstract

The present application relates to the field of electronic equipment technology, specifically disclosing a high-reliability glue-coated inductor and a method for preparing the same. The present application defines the raw material components of the magnet and magnetic glue, selecting a first magnetic powder containing both chromium and aluminum and a second magnetic powder as a matching component. During the magnet molding process, after hydrogen reduction treatment, a reduction product layer composed of metallic chromium and metallic aluminum can form on the outside of the oxide film between the powders. The silver in the electrode has good bonding ability with the chromium and aluminum in the reduction product layer, which helps to enhance the peeling force of the electrode, reduces the possibility of disconnection between the electrode and the magnet, and fully meets the current product reliability requirements of automotive electronic equipment.

Description

Technical Field

[0001] The present application relates to the technical field of electronic equipment, and more specifically, to a high-reliability glue-coated inductor and a preparation method thereof. Background Art

[0002] As automotive electronics become increasingly integrated, the number of functional modules continues to grow, including infotainment systems, advanced driver assistance systems (ADAS), electronic stability programs (ESP), and in-vehicle communication modules. These diverse systems often require different voltages for normal operation, while a vehicle's battery typically only provides a limited number of voltage outputs. This requires the vehicle's power system to accurately convert voltages.

[0003] As a key component in voltage conversion modules, inductors play an indispensable role in the voltage conversion process. By storing and releasing energy, inductors stabilize the current in the circuit, helping to maintain voltage continuity and consistency. In DC / DC converters, inductors convert the high voltage provided by the battery into a low voltage suitable for various electronic modules. They can also boost low voltage to a high voltage for specific high-power devices. With the rise of electric vehicles (EVs) and hybrid electric vehicles (HEVs), the role of inductors has become even more prominent. The battery systems of new energy vehicles require more efficient voltage management and conversion technologies to support the operation of the electric motor and power the onboard electronic devices. Inductors must not only withstand high currents but also maintain stable performance under various vehicle operating conditions, placing higher demands on their quality and reliability.

[0004] In the related art, there is an I-shaped cross-section inductor, which is prepared according to the following method: (1) iron silicon soft magnetic powder (FeSi) and a binder are mixed, and a green body is obtained after molding. The green body is sintered at 800°C for 3 hours, and then subjected to hydrogen reduction treatment at 850°C for 0.3 hours to obtain a magnet for use; iron silicon soft magnetic powder (FeSi) and epoxy resin are mixed to obtain magnetic glue, which is set aside; (2) a winding is wound on the outside of the magnet, and then the magnetic glue is coated on the outside of the winding. Finally, a silver electrode is welded to the bottom of the magnet to obtain an I-shaped cross-section inductor.

[0005] Regarding the above-mentioned related technologies, the inventors believe that although the I-shaped inductors in the related technologies have a certain degree of reliability, the electrodes therein may still peel off during use, resulting in disconnection between the inductor and the electrodes, making it difficult to fully meet the current product reliability requirements of automotive electronic equipment. Summary of the Invention

[0006] In related technologies, the electrodes may still peel off during use, resulting in disconnection between the inductor and the electrodes, making it difficult to fully meet the product reliability requirements of current automotive electronic equipment. To improve this defect, this application provides a high-reliability glue-coated inductor and its preparation method.

[0007] In a first aspect, the present application provides a high-reliability adhesive-coated inductor, which adopts the following technical solution:

[0008] A high-reliability glue-coated inductor comprises a magnet, a winding, and magnetic glue, wherein the winding is wound on the magnet, the magnetic glue is coated on the outside of the winding, and an external electrode is welded to the bottom of the magnet. The raw material components of the magnet include a first magnetic powder and a second magnetic powder, wherein the elemental composition of the first magnetic powder is: 74-88wt% Fe, 4-8wt% Si, 7-15wt% Cr, and 1%-3wt% Al, and the components of the second magnetic powder include at least one of FeSiCr, FeSiAl, and FeSi, and the first magnetic powder accounts for 80-95wt% of the powder raw material components of the magnet. The components of the magnetic glue include a third magnetic powder and epoxy resin, wherein the third magnetic powder is modified carbonyl iron powder, and the modified carbonyl iron powder is carbonyl iron powder coated with an inorganic protective layer.

[0009] By adopting the above-mentioned technical solution, this application defines the raw material components of the magnet and magnetic glue, selecting a first magnetic powder containing both chromium and aluminum and a second magnetic powder as a complementary component. During the magnet forming process, chromium and aluminum can increase the thickness of the oxide film between the powder particles, improving the bonding between the powder particles. After hydrogen reduction treatment, a reduction product layer composed of metallic chromium and metallic aluminum can form on the outside of the oxide film. The silver in the electrode has good bonding ability with the chromium and aluminum in the reduction product layer, which helps to enhance the peeling force of the electrode, reduces the possibility of disconnection between the electrode and the magnet, and fully meets the product reliability requirements of current automotive electronic equipment.

[0010] Preferably, the modified carbonyl iron powder is prepared according to the following method:

[0011] (1) Degreasing the carbonyl iron powder with ethanol, and then drying the carbonyl iron powder for later use; preparing phosphoric acid solution as a phosphating agent for later use;

[0012] (2) Add carbonyl iron powder to the phosphating solution, and obtain passivated iron powder after mechanical stirring. Mix the passivated iron powder with magnesium powder and place it in a vacuum tube furnace. After vacuum calcination, cool it in the furnace to obtain modified carbonyl iron powder.

[0013] By adopting the above technical solution, the present application first uses phosphoric acid to phosphate the carbonyl iron powder, forming a phosphate protective layer on the surface of the carbonyl iron powder to obtain passivated iron powder. Then, the present application co-calcines the passivated iron powder and magnesium powder under vacuum conditions, and the magnesium element slowly evaporates under high temperature conditions, while the phosphate decomposes under high temperature conditions to release oxygen. The vapor formed by the magnesium element can combine with the oxygen released by the phosphate and deposit on the surface of the phosphate protective layer to form a magnesium oxide protective layer. Under the double coating of phosphate and magnesium oxide, the modified carbonyl iron powder can have a higher magnetic permeability, thereby enhancing the inductance performance of the inductor device.

[0014] Preferably, the magnesium content of the modified carbonyl iron powder is 0.1-0.5 wt %.

[0015] By adopting the above technical solution, the present application optimizes the magnesium content in the modified carbonyl iron powder. Within this content range, magnesium oxide can form a coating on the surface of the phosphate protective layer, which helps to obtain modified carbonyl iron powder with higher magnetic permeability.

[0016] Preferably, the magnesium content of the modified carbonyl iron powder is 0.2-0.4 wt %.

[0017] By adopting the above technical solution, when magnesium oxide is excessively coated on the surface of the phosphate protective layer, the magnetic properties of the modified carbonyl iron powder are actually affected. However, within the above range, the modified carbonyl iron powder can have good magnetic properties and also help enhance the inductance performance of the inductor device.

[0018] Preferably, the modified carbonyl iron powder is prepared according to the following method:

[0019] The carbonyl iron powder is mixed with a solvent and stirred to obtain an iron powder dispersion, TEOS, aluminum sol and ammonia water are added to the iron powder dispersion, stirred and reacted, and then evaporated to dryness to obtain modified carbonyl iron powder.

[0020] By adopting the above technical solution, the present application uses TEOS as the silicon source and silica sol as the aluminum source, and uses ammonia water to promote the condensation of TEOS and aluminum sol, forming an inorganic coating layer composed of silica and alumina on the surface of the carbonyl iron powder, thereby obtaining a modified carbonyl iron powder with good magnetic properties.

[0021] Preferably, the solvent is at least one of ethanol and water.

[0022] By adopting the above technical solution, the present application optimizes the solvent type used in the preparation of the inorganic coating layer. While water can better promote the hydrolysis of TEOS, it also affects the bonding of the TEOS hydrolysis product with the carbonyl iron powder. Therefore, when ethanol is used as the solvent, the inorganic coating layer is more effective in coating the carbonyl iron powder, helping to increase the magnetic permeability of the modified carbonyl iron powder and also enhancing the inductive performance of the inductor device.

[0023] Preferably, the average particle size of the first magnetic powder is greater than the average particle size of the second magnetic powder, the particle size distribution of the first magnetic powder is 5-35 μm, and the particle size distribution of the second magnetic powder is 1-8 μm.

[0024] By adopting the above technical solution, the present application limits the particle size of the first magnetic powder and the second magnetic powder, which helps to improve the inductance performance of the inductor device.

[0025] Preferably, the particle size distribution of the third magnetic powder is 3-12 μm.

[0026] By adopting the above technical solution, the present application limits the particle size of the third magnetic powder, which helps to improve the inductance performance of the inductor device.

[0027] Preferably, the weight of the third magnetic powder accounts for 75-90% of the total weight of the magnetic glue.

[0028] By adopting the above technical solution, the present application limits the proportion of the third magnetic powder in the magnetic glue, which helps to improve the inductive performance of the inductive device.

[0029] In a second aspect, the present application provides a method for preparing a high-reliability adhesive-coated inductor, which adopts the following technical solution.

[0030] A method for preparing a high-reliability glue-coated inductor comprises the following steps:

[0031] (1) The first magnetic powder, the second magnetic powder and the binder are mixed, and a green body is obtained after compression molding. The green body is sintered at 800°C for 3-5 hours, and then subjected to hydrogen reduction treatment at 850°C for 0.3-1 hour to obtain a magnet for standby use; the third magnetic powder is mixed with epoxy resin to obtain a magnetic glue for standby use;

[0032] (2) Winding is placed on the outside of the magnet, then magnetic glue is coated on the outside of the winding, and finally silver electrodes are welded to the bottom of the magnet to obtain a high-reliability glue-coated inductor.

[0033] By adopting the above technical solution, the present application first uses the first and second magnetic powders as raw materials and, with the aid of a binder, prepares a green body. Then, the present application forms an oxide layer between the powders through high-temperature sintering, and then reduces the surface of the oxide layer to a single substance through hydrogen reduction treatment, thereby obtaining a magnet with good bonding ability with the silver electrode. By winding the outside of the magnet and applying magnetic glue, an inductor with high reliability and excellent magnetic properties can be obtained.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. This application defines the raw material components of the magnet and magnetic glue, selecting a first magnetic powder containing both chromium and aluminum and a second magnetic powder as a complementary component. During the magnet forming process, after hydrogen reduction treatment, a reduction product layer composed of metallic chromium and aluminum forms outside the oxide film between the powders. The silver in the electrode has good bonding with the chromium and aluminum in the reduction product layer, which helps enhance the peeling force of the electrode and reduces the possibility of disconnection between the electrode and the magnet, fully meeting the product reliability requirements of current automotive electronic equipment.

[0036] 2. In this application, phosphate and silicate are preferably used as inorganic coating layers to coat the carbonyl iron powder, and magnesium oxide is further introduced on the basis of phosphate, and aluminum oxide is further introduced on the basis of silicate, thereby achieving a good coating effect and obtaining modified carbonyl iron powder with higher magnetic permeability.

[0037] 3. The method of this application first prepares a green body, then sintering it at high temperature to form an oxide layer between the powders. Then, hydrogen reduction treatment reduces the oxide layer surface to its elemental form, resulting in a magnet with good bonding ability to the silver electrode. By winding the magnet outside and applying magnetic adhesive, an inductor with high reliability and excellent magnetic properties can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a front view of the high-reliability glue-coated inductor according to an embodiment of the present application.

[0039] Figure 2 4 is a bottom view of the high-reliability adhesive-coated inductor according to an embodiment of the present application.

[0040] Description of reference numerals:

[0041] 1. Magnet; 2. Winding; 3. Magnetic glue; 4. External electrode; 5. Precipitation transition layer. DETAILED DESCRIPTION

[0042] The present application is further described in detail below with reference to the Examples, Preparation Examples and Comparative Examples. The raw materials involved in the present application can all be obtained commercially.

[0043] The following is an explanation using Preparation Example 1.

[0044] Preparation Example 1

[0045] In this preparation example, the aluminum sol is prepared by adding aluminum isopropoxide to isopropanol and stirring. After ultrasonic dispersion, the aluminum alcohol phase is added dropwise to an aqueous phase in which polyvinyl pyrrolidone (the amount used is 1% of the total weight of aluminum isopropoxide) is dissolved at a water-alcohol ratio of 100:1 (weight ratio). The mixture is then stirred at a constant temperature of 90° C. After complete hydrolysis, nitric acid is added at a molar ratio of nitric acid:aluminum isopropoxide = 4:1, and the mixture is stirred at a constant temperature to obtain an aluminum sol.

[0046] In this preparation example, the modified carbonyl iron powder was prepared according to the following method:

[0047] 60 g of carbonyl iron powder was mixed with 90 mL of solvent (deionized water) and stirred to obtain an iron powder dispersion. 3 mL of TEOS, 2 mL of aluminum sol and 1 mL of ammonia water were added to the iron powder dispersion. After stirring and reacting, the mixture was evaporated to dryness at 50°C to obtain modified carbonyl iron powder.

[0048] Preparation Example 2

[0049] The difference between this preparation example and preparation example 1 is that anhydrous ethanol is used as the solvent.

[0050] Preparation Example 3

[0051] In this preparation example, the modified carbonyl iron powder was prepared according to the following method:

[0052] (1) Weigh 40 g of carbonyl iron powder and place it in 50 mL of ethanol solution and mechanically stir for 30 min to complete oil removal. Then, dry the carbonyl iron powder at 50 ° C for 30 min and set aside. Prepare a phosphoric acid solution with a concentration of 0.04 g / mL as a phosphating agent and set aside.

[0053] (2) Carbonyl iron powder was added to the phosphating solution at a ratio of 2.5 g / mL. After 30 minutes of mechanical stirring, the passivated iron powder was obtained. The passivated iron powder was mixed with magnesium powder and placed in a vacuum tube furnace. The mixture was first vacuumed for 30 minutes, then heated to 650°C, kept warm for 1 hour, and then cooled with the furnace to obtain modified carbonyl iron powder with a magnesium content of 0.1 wt%.

[0054] As shown in Table 1, the difference between Preparation Examples 3-7 is that the magnesium content of the modified carbonyl iron powder is different.

[0055] Table 1 Magnesium content of modified carbonyl iron powder

[0056]

[0057] In the following examples and comparative examples, the Fe content of FeSiCr is 93.5 wt %, the Si content is 3.5 wt %, and the Cr content is 3.0 wt %; the Fe content of FeSi is 96.5 wt %, the Si content is 3.5 wt %; and the Fe content of FeSiAl is 92.5 wt %, the Si content is 3.5 wt %, and the Al content is 4 wt %.

[0058] The following description will be made using Example 1 as an example.

[0059] Example 1

[0060] This embodiment provides a high reliability glue coated inductor, referring to Figure 1 、 Figure 2 The high-reliability coated inductor includes a magnet 1, a winding 2 and magnetic glue 3. The cross-section of the magnet 1 is an "I" shape. The winding 2 is spirally wound on the middle column of the "I" structure of the magnet 1. The magnetic glue 3 is wrapped around the outside of the winding 2. An external electrode 4 (silver electrode) is welded to the bottom of the magnet 1. A precipitation transition layer 5 is formed in the area where the external electrode 4 contacts the magnet 1.

[0061] In this embodiment, the raw material components of the magnet include a first magnetic powder and a second magnetic powder. The elemental composition of the first magnetic powder (referred to as the first magnetic powder composition) is: 74wt% Fe, 8wt% Si, 15wt% Cr, 3wt% Al, and the particle size distribution of the first magnetic powder is 5-35μm; the component of the second magnetic powder is FeSiCr, and the particle size distribution of the second magnetic powder is 1-8μm. The proportion of the first magnetic powder in the powder raw material components of the magnet (referred to as the first magnetic powder proportion) is 95wt%.

[0062] In this embodiment, the adhesive is prepared by mixing bisphenol A epoxy resin, curing agent 2-methylimidazole, plasticizer di(2-ethylhexyl) phthalate, and aluminate coupling agent. The amount of the curing agent is 30% by weight of the bisphenol A epoxy resin, the amount of the plasticizer is 1% by weight of the bisphenol A epoxy resin, and the amount of the aluminate coupling agent is 3% by weight of the bisphenol A epoxy resin.

[0063] In this embodiment, the weight of the third magnetic powder accounts for 75% of the total weight of the magnetic glue (referred to as the third magnetic powder proportion), and the remaining 25% is adhesive; the third magnetic powder is the modified carbonyl iron powder of Preparation Example 1, and the particle size distribution of the modified carbonyl iron powder is 3-12 μm.

[0064] This embodiment provides a method for preparing a high-reliability adhesive-coated inductor, comprising the following steps:

[0065] (1) The first magnetic powder, the second magnetic powder and the binder are mixed and molded to obtain a green body, which is sintered at 800°C for 3 hours and then subjected to hydrogen reduction treatment at 850°C for 0.3 hours to obtain a magnet for later use; the third magnetic powder is mixed with epoxy resin to obtain magnetic glue for later use; in this step, the weight of the epoxy resin in the binder is 2% of the total weight of the first magnetic powder and the second magnetic powder;

[0066] (2) Winding is placed on the outside of the magnet, then magnetic glue is coated on the outside of the winding, and finally silver electrodes are welded to the bottom of the magnet to obtain a high-reliability glue-coated inductor.

[0067] As shown in Table 2, the differences between Examples 1-3 mainly lie in the different production and processing parameters.

[0068] Table 2 Production and processing parameters

[0069]

[0070] As shown in Table 3, the difference between Examples 3-9 is that the preparation examples of the modified carbonyl iron powder are different.

[0071] Table 3 Preparation example of modified carbonyl iron powder

[0072]

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that the first magnetic powder, the second magnetic powder and the third magnetic powder are all replaced by FeSi.

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 1 is that the first magnetic powder is replaced by FeSi.

[0077] Comparative Example 3

[0078] The difference between this comparative example and Example 1 is that the first magnetic powder does not contain aluminum.

[0079] Comparative Example 4

[0080] The difference between this comparative example and Example 1 is that the first magnetic powder does not contain chromium.

[0081] 1. Inductance

[0082] The inductance value L of the sample was tested using a 3260B LCR meter. The results are shown in Table 4.

[0083] 2. Electrode peeling force

[0084] The electrode peeling force of the samples was tested using a tensile testing machine. The results are shown in Table 4.

[0085] Table 4 Test results

[0086]

[0087] Combining Examples 1-3 with Comparative Examples 1-2 and Table 4, it can be seen that the electrode peeling forces measured in Examples 1-3 are all relatively high. This is because, after hydrogen reduction treatment, a reduction product layer composed of metallic chromium and aluminum forms on the outer surface of the oxide film. The silver in the electrode has good bonding with the chromium and aluminum in the reduction product layer, which helps enhance the electrode peeling force and reduces the possibility of disconnection between the electrode and the magnet, fully meeting the product reliability requirements of current automotive electronic equipment. Comparative Examples 1-2, on the other hand, have relatively low aluminum and chromium contents, resulting in relatively low electrode peeling forces.

[0088] Combining Example 1 and Comparative Examples 3-4 with Table 4, it can be seen that the electrode peeling force measured in Example 1 is relatively high, indicating that when the first magnetic powder lacks any one of aluminum and chromium, it will have a greater impact on the electrode peeling force.

[0089] Combining Example 3 and Example 4 with Table 4, it can be seen that the inductance value measured in Example 4 is higher. This is because when ethanol is selected as the solvent, the inorganic coating layer has a better coating effect on the carbonyl iron powder, which helps to improve the magnetic permeability of the modified carbonyl iron powder and also helps to enhance the inductance performance of the inductor device.

[0090] Combining Example 4 and Example 5 and Table 4, it can be seen that the inductance value measured in Example 5 is higher, indicating that under the double coating of phosphate and magnesium oxide, the modified carbonyl iron powder can have a higher magnetic permeability, thereby enhancing the inductance performance of the inductor device.

[0091] From Examples 5-9 and Table 4, it can be seen that when the magnesium content of the modified carbonyl iron powder is within the range of 0.2-0.4, the modified carbonyl iron powder can have better magnetic properties, thus helping to enhance the inductance performance of the inductor device.

[0092] The above embodiments are merely explanations of the present application and are not limitations of the present application. After reading this specification, those skilled in the art may make modifications to the embodiments of the present application as needed without any creative contribution. However, as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A high reliability glue coated inductor, characterized in that: The invention comprises a magnet (1), a winding (2) and a magnetic glue (3), wherein the winding (2) is wound on the magnet (1), the magnetic glue (3) is coated on the outside of the winding (2), and an external electrode (4) is welded to the bottom of the magnet (1); the raw material components of the magnet include a first magnetic powder and a second magnetic powder, the element composition of the first magnetic powder is: 74-88wt% Fe, 4-8wt% Si, 7-15wt% Cr, 1%-3wt% Al, the components of the second magnetic powder include at least one of FeSiCr, FeSiAl, and FeSi, and the first magnetic powder accounts for 80-95wt% of the powder raw material components of the magnet; the components of the magnetic glue include a third magnetic powder and epoxy resin, the third magnetic powder is modified carbonyl iron powder, and the modified carbonyl iron powder is carbonyl iron powder with an inorganic protective layer coated on the surface.

2. The high reliability coated inductor according to claim 1, characterized in that: The modified carbonyl iron powder is prepared according to the following method: (1) Degreasing the carbonyl iron powder with ethanol, and then drying the carbonyl iron powder for later use; preparing phosphoric acid solution as a phosphating agent for later use; (2) Add carbonyl iron powder to the phosphating solution, and obtain passivated iron powder after mechanical stirring. Mix the passivated iron powder with magnesium powder and place it in a vacuum tube furnace. After vacuum calcination, cool it in the furnace to obtain modified carbonyl iron powder.

3. The high reliability adhesive coated inductor according to claim 2, characterized in that: The magnesium content of the modified carbonyl iron powder is 0.1-0.5 wt %.

4. The high reliability coated inductor according to claim 3, characterized in that: The magnesium content of the modified carbonyl iron powder is 0.2-0.4 wt %.

5. The high reliability coated inductor according to claim 1, characterized in that: The modified carbonyl iron powder is prepared according to the following method: The carbonyl iron powder is mixed with a solvent and stirred to obtain an iron powder dispersion, TEOS, aluminum sol and ammonia water are added to the iron powder dispersion, stirred and reacted, and then evaporated to dryness to obtain modified carbonyl iron powder.

6. The high reliability adhesive coated inductor according to claim 5, characterized in that: The solvent is at least one of ethanol and water.

7. The high reliability coated inductor according to claim 1, characterized in that: The average particle size of the first magnetic powder is greater than the average particle size of the second magnetic powder. The particle size distribution of the first magnetic powder is 5-35 μm, and the particle size distribution of the second magnetic powder is 1-8 μm.

8. The high reliability adhesive coated inductor according to claim 1, characterized in that: The particle size distribution of the third magnetic powder is 3-12 μm.

9. The high reliability adhesive coated inductor according to claim 8, characterized in that: The weight of the third magnetic powder accounts for 75-90% of the total weight of the magnetic glue.

10. The method for preparing a high-reliability coated inductor according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) The first magnetic powder, the second magnetic powder and the binder are mixed, and a green body is obtained after compression molding. The green body is sintered at 800°C for 3-5 hours, and then subjected to hydrogen reduction treatment at 850°C for 0.3-1 hour to obtain a magnet for standby use; the third magnetic powder is mixed with epoxy resin to obtain a magnetic glue for standby use; (2) Winding is placed on the outside of the magnet, then magnetic glue is coated on the outside of the winding, and finally silver electrodes are welded to the bottom of the magnet to obtain a high-reliability glue-coated inductor.

Images