Ferrite core composition and method for preparing ferrite core

Abstract

Provided are: a ferrite core composition comprising a castable and insulating additive containing Mn, Zn, Fe, and Ni; and a method for preparing same, wherein an atomic ratio of Mn is in the range of 0.39270 to 0.39392, an atomic ratio of Zn is in the range of 0.19870 to 0.19939, an atomic ratio of Fe is in the range of 2.3943 to 2.40094, and an atomic ratio of Ni is in the range of 0.00861 to 0.01432.

Description

Ferrite core composition and method for manufacturing a ferrite core

[0001] The present invention relates to a ferrite core composition having a high saturation magnetic flux density and a method for manufacturing a ferrite core.

[0002] Ferrite is an oxide-based magnetic material with Fe2O3 as its main component. Ferrite cores are manufactured by compressing and sintering the ferrite material and serve as the magnetic core used in the main transformer and output inductor of automotive low-voltage DC-DC converters; specifically, they act as the pathway (magnetic core) for magnetic field lines generated by current changes in the Cu coil.

[0003] Figure 1 is a graph of the magnetic flux density of a conventional ferrite core. C1 represents the magnetic flux density of a metal ferrite core, C2 represents the magnetic flux density of a ferrite core for high saturation (High Bs), and C3 represents the magnetic flux density of a low-loss ferrite core.

[0004] Ferrite cores, which have lower losses compared to metal cores, are difficult to apply as they are because their inductance decreases sharply above 350 mT due to their relatively low saturation flux density, requiring a design that increases the size. When the size increases unnecessarily in this way, the amount of copper used increases, leading to heat generation and a problem of rising manufacturing costs.

[0005] The magnetic flux density (B) can be calculated according to the following formula.

[0006] [Equation 1]

[0007]

[0008] In the above equation, N is the number of winding turns, A is the cross-sectional area of ​​the core, l is the current, and L is the inductance.

[0009] As can be seen from the above equation regarding magnetic flux density, if the number of coil turns is increased to meet the required inductance value in a DC-DC converter circuit while keeping the size fixed, the external magnetic field may increase unintentionally, resulting in a decrease in the inductance value. In other words, in the case of conventional low-loss ferrite, if applied to a power module with a specific capacity (3.0kW) or higher, the saturation magnetic flux density decreases at high temperatures (100℃), making it impossible to meet the required inductance value of the module. Consequently, the size must be increased additionally to meet the required inductance value, and the amount of coil increases.

[0010] On the other hand, since automotive DC-DC converters have volume limitations such as width, length, and height, increasing the size to use ferrite, which has lower losses compared to metal cores, makes it impossible to apply them within limited spaces.

[0011] For example, the saturation flux density of currently existing ferrite cores with high saturation flux density is in the range of 430 to 450 mT (@100℃), but it must be at least 480 mT to be applicable to DC-DC converters (3.6 kW or more) without increasing size.

[0012] Therefore, there is a need to develop a ferrite core with high saturation magnetic flux density that can replace the currently applied metal core without increasing size.

[0013] The technical problem of the present invention is to provide a ferrite core composition having a high saturation magnetic flux density and a method for manufacturing a ferrite core that can be applied to an electric power module (DC-DC converter for mHEV) without increasing size.

[0014] One aspect of the present invention provides a ferrite core composition comprising castable and insulating additives including Mn, Zn, Fe, and Ni, wherein the atomic ratio of Mn is in the range of 0.39270 to 0.39392, the atomic ratio of Zn is in the range of 0.19870 to 0.19939, the atomic ratio of Fe is in the range of 2.3943 to 2.40094, and the atomic ratio of Ni is in the range of 0.00861 to 0.01432.

[0015] According to the example, the ratio of Mn:Zn may be 1.5:1 or higher.

[0016] According to the example, the insulating additive may be selected from one or more of CaO, SiO2, and Nb2O5.

[0017] According to the example, the insulating additive may include all of CaO, SiO2, and Nb2O5.

[0018] According to the examples, based on the total weight of the cast product, the content of CaO may be in the range of 0.1 to 1,000 ppm, the content of SiO2 may be in the range of 0.1 to 200 ppm, and the content of Nb2O5 may be in the range of 0.1 to 300 ppm, but is not limited thereto.

[0019] According to the example, the ferrite core composition may have a saturation magnetic flux density of 480 mT (@100℃) or more.

[0020] Another aspect of the present invention provides a method for manufacturing a ferrite core comprising the steps of: preparing a castable material by mixing Mn3O4, ZnO, Fe2O3, and NiO; adding and mixing CaO, SiO2, and Nb2O5 to the castable material; and sintering the mixed composition at a temperature of 1,300°C or higher for 4 hours or more.

[0021] The above castable material can be prepared by mixing Mn3O 48.49 to 8.54 mol%, ZnO 12.89 to 12.97 mol%, Fe2O 377.68 to 78.10 mol%, and NiO 0.56 to 0.93 mol%.

[0022] According to an example, in the method for manufacturing the ferrite core, the insulating additive may be added in such a way that, based on the total weight of the castable material, the content of CaO is in the range of 0.1 to 1,000 ppm, the content of SiO2 is in the range of 0.1 to 200 ppm, and the content of Nb2O5 is in the range of 0.1 to 300 ppm.

[0023] According to the example, the sintering temperature is preferably in the range of 1320℃ to 1350℃.

[0024] The present invention can provide a ferrite core composition having a high saturation magnetic flux density that can be applied to an electric power module (DC-DC converter for mHEV) without increasing size, and a method for manufacturing a ferrite core.

[0025] The MnZn ferrite core composition according to an embodiment of the present invention has a high saturation magnetic flux density of 480 mT (@100℃) or higher, and accordingly, can be applied to DC-DC converters of 3.6 kW or higher without increasing the size.

[0026] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below.

[0027] Figure 1 is a graph of the magnetic flux density of a ferrite core according to a comparative example.

[0028] Figure 2 is a graph of the magnetic flux density of a ferrite core according to an embodiment.

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0030] However, the technical concept of the present invention is not limited to some of the described embodiments but can be implemented in various different forms, and within the scope of the technical concept of the present invention, one or more of the components among the embodiments may be selectively combined or substituted.

[0031] In addition, terms used in the embodiments of the present invention (including technical and scientific terms) may be interpreted in a sense that is generally understood by those skilled in the art to which the present invention belongs, unless explicitly and specifically defined otherwise. Terms that are commonly used, such as terms defined in advance, may be interpreted in consideration of their meaning in the context of the relevant technology.

[0032] Furthermore, the terms used in the embodiments of the present invention are for the purpose of describing the embodiments and are not intended to limit the present invention.

[0033] In this specification, the singular form may include the plural form unless specifically stated otherwise in the text, and when described as "at least one of A and B and C (or more than one)," it may include one or more of all combinations that can be formed from A, B, and C.

[0034] In addition, terms such as first, second, A, B, (a), (b), etc. may be used when describing the components of the embodiments of the present invention.

[0035] These terms are intended merely to distinguish a component from other components and are not limited by the nature, order, sequence, etc., of the said component.

[0036] And where it is stated that a component is 'connected', 'combined', or 'joined' to another component, that component may include not only cases where it is directly connected, combined, or joined to the other component, but also cases where it is 'connected', 'combined', or 'joined' due to another component located between the component and the other component.

[0037] Furthermore, when described as being formed or placed "above or below" each component, "above" or "below" includes not only cases where two components are in direct contact with each other, but also cases where one or more other components are formed or placed between the two components. Additionally, when expressed as "above or below," it may include the meaning of a downward direction as well as an upward direction relative to a single component.

[0038] A ferrite core composition according to an embodiment of the present invention comprises castable and insulating additives including Mn, Zn, Fe, and Ni, wherein the atomic ratio of Mn is in the range of 0.39270 to 0.39392, the atomic ratio of Zn is in the range of 0.19870 to 0.19939, the atomic ratio of Fe is in the range of 2.3943 to 2.40094, and the atomic ratio of Ni is in the range of 0.00861 to 0.01432.

[0039] In addition, it is desirable that the ratio of Mn:Zn is 1.5:1 or higher.

[0040] In the above ferrite core composition, the insulating additive may be selected from one or more of CaO, SiO2, and Nb2O5, and it is preferable to include all of CaO, SiO2, and Nb2O5.

[0041] The specific content of the insulating additives may be based on the total weight of the casting, such that the content of CaO is 1,000 ppm or less, the content of SiO2 is 200 ppm or less, and the content of Nb2O5 is 300 ppm or less. For example, the content of CaO may be in the range of 0.1 to 1,000 ppm, the content of SiO2 may be in the range of 0.1 to 200 ppm, and the content of Nb2O5 may be in the range of 0.1 to 300 ppm, but is not limited thereto.

[0042] In the case of conventional low-loss ferrites, when applied to power modules of a specific capacity (3.0kW) or higher, the saturation flux density drops at high temperatures (100℃), making it impossible to meet the required inductance value; consequently, the size had to be increased to meet the required inductance. For example, to apply a conventional low-loss core to a 3.6kW module, the volume must be increased by approximately 20% to 30% to achieve the same performance, and even for conventional high-saturation flux cores, a volume increase of 10% to 20% is required.

[0043] Even in the case of existing ferrite cores with high saturation flux density, the saturation flux density is in the range of 430 to 450 mT (@100℃), but it must be at least 480 mT to be applicable to DC-DC converters (3.6 kW or more) without increasing the size.

[0044] In this invention, to develop a ferrite having a high saturation magnetic flux density compared to existing commercial products, optimization design for the following key factors was carried out step-by-step in terms of composition / process design.

[0045] First, in Step 1, the castability content ratio (Fe, Mn, Zn, Ni) of the ferrite core composition was optimized. In Step 2, non-magnetic additives (CaO, SiO2, Nb2O5, ZrO2, The content of V2O5 was optimized. Then, the process conditions were adjusted in three steps after heat treatment.

[0046] The composition of the ferrite core according to an embodiment of the present invention was obtained through the following experiment.

[0047] First, the change in magnetic flux density according to the atomic weight ratio of the castables was measured to define the castable content ratio (Fe, Mn, Zn, Ni).

[0048] A search for compositions within the compositional range of ① Fe+Co = 2.025 ~ 2.325 and ② Mn and Zn atomic ratio (Mn / Zn atomic ratio) = 1 ~ 12 was conducted, and experiments were performed on the top 15 compositions out of approximately 250 compositions. Table 1 below shows the castability mixing ratios and the measured saturation magnetic flux density (Bs) at 100°C.

[0049] ExampleMnZnFeNiSiO2Nb2O5CaOBs@100℃ [mT]Density(g / cc)stoichiometry[ppm]1-10.671580.160012.168410.00000003005004324.801-20.671580.160012.168410.00000 00004354.811-30.393920.199392.400940.00576(1,800)03001,0004744.721-40.393920.199392.400940.00576(1,800)0004604.66

[0050] Next, to optimize the Ni content, the saturation magnetic flux density was checked according to the Ni content after fixing the mixing ratio of Fe, Mn, and Ni. As shown in Table 2 below, the saturation magnetic flux density was measured to be high when the Ni content was in the range of 2,700 ppm to 4,500 ppm.

[0051] Example MnZnFeNiSiO2Nb2O5CaOBs@100℃ [mT]Density (g / cc)stoichiometry[ppm]2-10.394500.199702.405800.00000003001,0004544.662-20.394200.199472.403500.00288(900)03001,0004614.702- 30.393400.199102.398900.00861(2,700)03001,0004704.703-10.386300 .195502.355600.06262(20,000)03001,0004274.603-20.378400.191502. 307400.12268(40,000)03001,0004164.583-30.370800.187702.261200.18034(60,000)03001,0004084.574-10.393000.198902.396600.01147(3,6 00)03001,0004594.694-20.392700.198702.394300.01432(4,500)03001,0004734.744-30.392300.198502.392000.01717(5,400)03001,0004594.69

[0052] Through the above experiment, it can be confirmed that a ferrite core having a high saturation magnetic flux density is obtained when, in the castability of the ferrite core composition, the atomic ratio of Mn is in the range of 0.39270 to 0.39392, the atomic ratio of Zn is in the range of 0.19870 to 0.19939, the atomic ratio of Fe is in the range of 2.3943 to 2.40094, and the atomic ratio of Ni is in the range of 0.00861 to 0.01432, and regarding the insulating additives based on the total weight of the castability, the content of CaO is in the range of 0.1 to 1,000 ppm, the content of SiO2 is in the range of 0.1 to 200 ppm, and the content of Nb2O5 is in the range of 0.1 to 300 ppm.

[0053] In addition, magnetic flux density was measured while varying the ratio of Mn to Zn in the ferrite core composition to 1:1, 1.5:1, and 3:1. As shown in Table 3 below, it was confirmed that the saturation magnetic flux density increases when the ratio of Mn to Zn is 1.5:1 or higher.

[0054] ExampleMnZnFeNiSiO2Nb2O5CaOBs@100℃ [mT]Density(g / cc)stoichiometry[ppm]5-1(MnZn1)0.296250.296252.398900. 00861(2,700)03001,0004564.685-2(MnZn1.5)0.355500.237002.398900.00861( 2,700)03001,0004684.755-3(MnZn3)0.444380.148132.398900.00861(2,700)0 3001,0004814.702-30.393400.199102.398900.00861(2,700)03001,0004844.77

[0055] A method for manufacturing a ferrite core according to an embodiment of the present invention comprises the steps of: preparing a castable material by mixing Mn3O4, ZnO, Fe2O3, and NiO; adding and mixing CaO, SiO2, and Nb2O5 to the castable material; and sintering the mixed composition at a temperature of 1,300°C or higher for 4 hours or more.

[0056] The above castable material can be prepared by mixing Mn3O 48.49~8.54 mol%, ZnO 12.89~12.97 mol%, Fe2O 377.68~78.10 mol%, and NiO 0.56~0.93 mol%.

[0057] In addition, in the method for manufacturing the ferrite core, the insulating additive may be added based on the total weight of the castable material such that the content of CaO is in the range of 0.1 to 1,000 ppm, the content of SiO2 is in the range of 0.1 to 200 ppm, and the content of Nb2O5 is in the range of 0.1 to 300 ppm.

[0058] In order to optimize the heat treatment process in the method of manufacturing a ferrite core, the physical properties of the ferrite core were measured by varying the sintering temperature and holding time, and the results are shown in Table 4 and Figure 2 below. Figure 2 shows a graph of the change in magnetic flux density according to temperature for ferrite cores having the compositions of Examples 2-3 containing 0, 100 ppm, and 200 ppm of Si, respectively.

[0059] Referring to Table 4 and Figure 2, it can be confirmed that a ferrite core having a high saturation magnetic flux density of 480 mT or more was produced when the ferrite core was maintained at a sintering temperature of 1,300°C or higher for 4 hours or more, preferably at 1,320°C to 1,350°C, and more preferably at 1,330°C for about 4 hours during the manufacturing process.

[0060] Sample nameMnZnFeNiSiO2Nb2O5CaOBs@100℃ [mT]Density(g / cc)stoichiometry[ppm]5-1 (MnZn1)0.296250.296252.398900.00861(2,700)03001,0004384.685-2 (MnZn1.5)0.355500.237002.398900.00861(2,700)03001,0004714.755-3 (MnZn3)0.444380.148132.398900.00861(2,700)03001,0004774.702-3.Si1000.393400.199102.398 900.00861(2,700)1003001,0004814.732-3.Si2000.393400.199102.398900.00861(2,700)2003001, 0004824.811-30.393920.199392.400940.00576(1,800)03001,0004844.742-30.393400.199102.398900.00861(2,700)03001,0004834.774-10.393000.198902.396600.01147(3,600)03001,0004854.79

[0061] As such, the MnZn ferrite core composition according to the embodiment of the present invention has a high saturation magnetic flux density of 480 mT (@100℃) or higher, and accordingly, it can be applied to DC-DC converters of 3.6 kW or higher without increasing the size.

[0062] From the foregoing description, those skilled in the art to which the present invention pertains will understand that the present invention may be implemented in other specific forms without altering its technical concept or essential features. In this regard, the above embodiments should be understood as illustrative in all respects and not restrictive. The scope of the present invention should be interpreted as including all modifications or variations derived from the meaning and scope of the claims set forth below and their equivalents, rather than from the above detailed description.

Claims

1. A ferrite core composition comprising castable and insulating additives including Mn, Zn, Fe, and Ni, The atomic ratio of the above Mn is in the range of 0.39270 to 0.39392, and The atomic weight ratio of the above Zn is in the range of 0.19870 to 0.19939, and The atomic weight ratio of the above Fe is in the range of 2.3943 to 2.40094, and A ferrite core composition in which the atomic weight ratio of Ni is in the range of 0.00861 to 0.01432.

2. In Paragraph 1, A ferrite core composition in which the ratio of Mn:Zn is 1.5:1 or higher.

3. In Paragraph 1, The above insulating additive is one or more selected from CaO, SiO2, and Nb2O5, in a ferrite core composition.

4. In Paragraph 3, The above insulating additive is a ferrite core composition containing all of CaO, SiO2, and Nb2O5.

5. In Paragraph 4, Based on the total weight of the above-mentioned cast product, The content of the above CaO is in the range of 0.1 to 1,000 ppm, and The content of the above SiO2 is in the range of 0.1 to 200 ppm, and A ferrite core composition having a Nb2O5 content in the range of 0.1 to 300 ppm.

6. In Paragraph 1, Ferrite core composition having a magnetic flux density of 480 mT (@100℃) or higher.

7. A step of preparing a castable material by mixing Mn3O4, ZnO, Fe2O3, and NiO; Step of adding and mixing CaO, SiO2, and Nb2O5 to the above-mentioned castable material: A method for manufacturing a ferrite core comprising the step of sintering the above-mentioned mixed composition at a temperature of 1,300°C or higher for 4 hours or more.

8. In Paragraph 7, A method for manufacturing a ferrite core, wherein the above-mentioned castable material is a mixture of Mn3O 48.49 to 8.54 mol%, ZnO 12.89 to 12.97 mol%, Fe2O 377.68 to 78.10 mol%, and NiO 0.56 to 0.93 mol%.

9. In Paragraph 7, Based on the total weight of the above-mentioned castable material, The content of the above CaO is in the range of 0.1 to 1,000 ppm, and The content of the above SiO2 is in the range of 0.1 to 200 ppm, and A method for manufacturing a ferrite core in which the above Nb2O5 content is added in the range of 0.1 to 300 ppm.

10. In Paragraph 7, A method for manufacturing a ferrite core in which the sintering temperature is in the range of 1320℃ to 1350℃.

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