Moisture-resistant soft magnetic composite material and method for manufacturing the same, and integrally formed inductor

Abstract

The application relates to the technical field of integrally-formed inductors, in particular to a moisture-resistant soft magnetic composite material and a preparation method thereof and an integrally-formed inductor. The moisture-resistant soft magnetic composite material comprises the following components by mass: 100 parts of soft magnetic powder, 2-5 parts of a resin bonding agent and silicon resin, wherein the mass ratio of the silicon resin to the resin bonding agent is (0.3-2.0):100. The moisture-resistant soft magnetic composite material can avoid the phenomenon of explosion of the integrally-formed inductor during a reflow soldering process after moisture absorption.

Description

Technical Field

[0001] This invention relates to the field of integrally molded inductor technology, and more specifically, to a moisture-resistant soft magnetic composite material, its preparation method, and an integrally molded inductor. Background Technology

[0002] Molded inductors are increasingly widely used due to their advantages such as miniaturization, strong electromagnetic interference resistance, low noise, and high frequency operation. A molded inductor is mainly composed of soft magnetic powder and a binder. The soft magnetic powder contributes to the electromagnetic properties, while the binder helps to reduce losses by blocking eddy current transmission between the powder particles and, after curing, improves the bonding force between the soft magnetic powder particles. If a molded inductor absorbs too much moisture during storage, the moisture will vaporize during subsequent reflow soldering, causing it to burst. Summary of the Invention

[0003] Therefore, it is necessary to provide a moisture-resistant soft magnetic composite material and its preparation method, as well as a one-piece molded inductor. This moisture-resistant soft magnetic composite material can effectively suppress the moisture absorption of the one-piece molded inductor, thereby reducing the occurrence of cracking during subsequent reflow soldering.

[0004] In one aspect, the present invention provides a moisture-resistant soft magnetic composite material, comprising the following components in parts by weight:

[0005] 100 parts of soft magnetic powder

[0006] 2-5 parts of resin adhesive, and

[0007] The silicone resin and the resin adhesive are in a mass ratio of (0.3 to 2.0): 100.

[0008] In one embodiment, the mass ratio of the silicone resin to the resin adhesive is (0.3 to 1.0): 100.

[0009] In one embodiment, the soft magnetic powder includes one or more of carbonyl iron powder, iron-silicon-chromium powder, iron-silicon-aluminum powder, iron-silicon powder, nickel-iron soft magnetic alloy, amorphous iron powder, and nanocrystalline iron powder.

[0010] In one embodiment, the resin adhesive is prepared from raw materials including resin and curing agent, wherein the resin does not include silicone resin.

[0011] In one embodiment, the resin includes one or more of epoxy resin, phenolic resin, and cyanate ester.

[0012] In one embodiment, the curing agent includes one or more of acid anhydride curing agents and amine curing agents.

[0013] In one embodiment, the anhydride curing agent includes one or more of phthalic anhydride, maleic anhydride, and hexahydrophthalic anhydride.

[0014] In one embodiment, the amine curing agent includes one or more of diaminodiphenylmethane, m-phenylenediamine, and 4,4-diaminophenyl sulfone.

[0015] In one aspect, the present invention also provides a method for preparing the above-mentioned moisture-resistant soft magnetic composite material, which includes the following steps:

[0016] The soft magnetic powder, the resin binder, the silicone resin, and the organic solvent are mixed and granulated.

[0017] In one embodiment, the organic solvent includes one or more of acetone, N,N-dimethylformamide, and methyl acetate.

[0018] In one embodiment, a drying step is further included, wherein the drying temperature is 40°C to 80°C.

[0019] In another aspect, the present invention provides a molded inductor comprising the aforementioned moisture-resistant soft magnetic composite material and a coil embedded in the moisture-resistant soft magnetic composite material.

[0020] The aforementioned moisture-resistant soft magnetic composite material reduces hygroscopicity by adding silicone resin to the resin binder, thus preventing the molded inductor from absorbing excessive moisture during storage and reducing the likelihood of cracking during subsequent reflow soldering. The moisture absorption of the molded inductor during storage can be further controlled by adjusting the silicone resin content. In summary, adding silicone resin to the resin binder and controlling its content significantly improves the hygroscopicity of the molded inductor, thereby solving the problem of cracking during reflow soldering. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is an appearance view of the integrally molded inductor obtained in Embodiment 1 of the present invention after moisture absorption and reflow soldering;

[0023] Figure 2This is an appearance view of the integrally molded inductor obtained in Embodiment 2 of the present invention after moisture absorption and reflow soldering;

[0024] Figure 3 This is an appearance view of the integrally molded inductor obtained in Embodiment 3 of the present invention after moisture absorption and reflow soldering;

[0025] Figure 4 This is a view of the integrally molded inductor obtained in Comparative Example 1 of the present invention after moisture absorption and reflow soldering.

[0026] Figure 5 This is an appearance diagram of the integrally molded inductor obtained in Comparative Example 2 of the present invention after moisture absorption and reflow soldering. Detailed Implementation

[0027] Reference will now be made to detailed embodiments of the present invention, one or more of which are described below. Each example is provided for explanation and not for limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0028] Therefore, this invention is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of the invention are disclosed in or will be apparent from the following detailed description. It will be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the invention.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof as used herein are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises the listed elements is not necessarily limited to those elements but may include other elements not expressly listed or elements inherent to such a composition, step, method, article, or apparatus.

[0030] Unless otherwise shown or indicated in the operational embodiments, all figures used to represent the amounts, physicochemical properties, etc., of ingredients in the specification and claims are to be understood to be adjusted by the term "about" in all cases. For example, therefore, unless stated to the contrary, the numerical parameters listed in the foregoing specification and appended claims are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired characteristics by utilizing the teachings disclosed herein. The use of numerical ranges indicated by endpoints includes all numbers within that range and any range within that range; for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4, and 5, etc.

[0031] The first objective of this invention is to provide a moisture-resistant soft magnetic composite material, comprising the following components in parts by weight:

[0032] The mixture comprises 100 parts of soft magnetic powder, 2-5 parts of resin adhesive, and silicone resin, wherein the mass ratio of silicone resin to resin adhesive is (0.3-2.0):100.

[0033] The aforementioned moisture-resistant soft magnetic composite material reduces the hygroscopicity of the soft magnetic composite material by adding silicone resin to the resin binder. This prevents the molded inductor from absorbing excessive moisture during storage and reduces the likelihood of cracking during subsequent reflow soldering. The aforementioned moisture-resistant soft magnetic composite material significantly improves the hygroscopicity of the molded inductor, thereby solving the problem of cracking during reflow soldering.

[0034] In some embodiments, the mass percentage of silicone resin in the resin adhesive can be any value between (0.3 to 2.0):100. Exemplary examples include 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, 1.6:100, 1.7:100, 1.8:100, 1.9:100, and 2.0:100. By adjusting the mass percentage of silicone resin within this range, its moisture resistance can be significantly improved without affecting the magnetic properties of the integrally molded inductor. For example, to illustrate this: after adding silicone resin at a mass ratio of 2.0:100 to the resin adhesive, the integral molded inductor was subjected to moisture absorption for 240 hours at a temperature of 60℃ and a humidity of 95%RH, and then reflow soldered. The bursting rate of the integral molded inductor was 0.

[0035] In some embodiments, the silicone resin may be one or more of KBM-303 and KR-48.

[0036] In some embodiments, the soft magnetic powder is not limited in many ways, and any soft magnetic powder known in the art can be selected, including, but not limited to, one or more of carbonyl iron powder, iron-silicon-chromium powder, iron-silicon-aluminum powder, iron-silicon powder, nickel-iron soft magnetic alloy, amorphous iron powder and nanocrystalline iron powder.

[0037] In some embodiments, the resin adhesive may be any commonly used resin adhesive in the art, for example, one or more of epoxy resin adhesive, phenolic resin adhesive and cyanate ester adhesive.

[0038] In some embodiments, the resin adhesive can be prepared from raw materials including resin (other than silicone resin) and curing agent.

[0039] In some embodiments, the resin may be one or more of epoxy resin, phenolic resin, and cyanate ester.

[0040] In some embodiments, the type of curing agent is not limited, and those skilled in the art can select it according to conventional formulations. For example, the curing agent may be one or more of acid anhydride curing agents, amine curing agents, and imidazole curing agents.

[0041] The anhydride curing agent may be one or more of phthalic anhydride, maleic anhydride and hexahydrophthalic anhydride, and the amine curing agent may be one or more of diaminodiphenylmethane, m-phenylenediamine and 4,4-diaminophenyl sulfone.

[0042] In some implementations, the mass ratio of resin to curing agent can be selected according to actual needs, so that the curing agent can completely cure the resin without affecting the strength and magnetic properties of the soft magnetic composite material. For example, it can be 100:(6-50).

[0043] The second objective of this invention is to provide a method for preparing the above-mentioned moisture-resistant soft magnetic composite material, which includes the following steps:

[0044] The soft magnetic powder, resin binder, silicone resin and organic solvent are mixed and granulated.

[0045] In some embodiments, those skilled in the art may select any known organic solvent according to actual needs. For example, the organic solvent may be one or more of acetone, N,N-dimethylformamide and methyl acetate.

[0046] Preferably, the organic solvent is acetone.

[0047] In some implementations, granulation methods commonly used in the art can be selected for granulation, such as agglomeration granulation or extrusion granulation.

[0048] In some embodiments, the preparation method of the moisture-resistant soft magnetic composite material further includes a drying step. The drying method is not limited, for example, it can be ventilation drying or heating drying. The conditions for heating drying are also not limited, and the heating temperature and time can be any commonly used values. Preferably, the drying temperature can be 40℃~80℃ and the time can be 50min~120min.

[0049] A third objective of this invention is to provide an integrally molded inductor, comprising the aforementioned moisture-resistant soft magnetic composite material and a coil embedded within the moisture-resistant soft magnetic composite material.

[0050] In some embodiments, the method of embedding the coil in the moisture-resistant soft magnetic composite material can be any method known in the art, for example, it can be a powder metallurgy process.

[0051] In some implementations, the material and shape of the coil are not limited; for example, it can be a copper coil, and the coil shape can be circular, square, flat, multi-strand combination, etc.

[0052] In some implementations, the model number of the integrally molded inductor may also be a model number commonly used in the art, such as the 0640-R15 model, but is not limited thereto.

[0053] The present invention will be further described in detail below with reference to specific embodiments and comparative examples.

[0054] Example 1

[0055] 1) Raw materials for preparing moisture-resistant soft magnetic composite materials:

[0056] Take 100 parts by weight of soft magnetic powder Fe 92 Si 3.5 Cr 4.5 3 parts resin adhesive (composed of cyanate ester and 4,4'-diaminodiphenyl sulfone in a mass ratio of 100:6), 12 parts acetone, and silicone resin (KBM-303), wherein the silicone resin accounts for 0.3% of the mass percentage of the epoxy resin adhesive.

[0057] 2) Preparation process of moisture-resistant soft magnetic composite materials:

[0058] Dissolve the above-mentioned resin adhesive and silicone resin in acetone, mix thoroughly, and then add Fe. 92 Si 3.5 Cr 4.5 The powder was stirred evenly, granulated, and baked at 60°C for 1 hour to obtain a moisture-resistant soft magnetic composite material.

[0059] 3) Fabrication of integrally molded inductors

[0060] Using powder metallurgy, the coil winding is embedded in the aforementioned moisture-resistant soft magnetic composite material, pressed into shape, and baked to produce an integrally molded inductor with model number 0640-R15. The baking process is as follows: holding at 60℃ for 1 hour, then holding at 80℃ for 1 hour, then holding at 120℃ for 1 hour, and finally holding at 160℃ for 3 hours.

[0061] Performance testing:

[0062] 1) Cracking Test: 100 integrally molded inductors of model 0640-R15 were prepared and placed under conditions of 60℃ and 95%RH for 240 hours to absorb moisture. They were then placed in a reflow oven and left to stand at room temperature for 1 hour. The cracking rate was observed. Cracking was determined by whether the crack length on any face of the integrally molded inductor exceeded half the length of that face. If the crack length on any face exceeded half the length of that face, the product was considered cracked; otherwise, it was considered uncracking. The cracking rate is shown in Table 2. The product appearance is as follows. Figure 1 As shown;

[0063] 2) Relative permeability test: The moisture-resistant soft magnetic composite material prepared above was pressed into a magnetic ring with OD=14mm and ID=8mm under a pressure of 5T, and wound with 13.5 turns of copper wire with a diameter of 0.5mm. Finally, the inductance value was tested with a Tonghui TH-2829 LCR meter, and the relative permeability was finally calculated, as shown in Table 2.

[0064] Example 2

[0065] The preparation method in this embodiment is basically the same as that in Example 1, except that the silicone resin accounts for 1.0% of the mass of the epoxy resin adhesive. The specific steps are as follows:

[0066] 1) Raw materials for preparing moisture-resistant soft magnetic composite materials:

[0067] Take 100 parts by weight of soft magnetic powder Fe 92 Si 3.5 Cr 4.5 3 parts resin adhesive (composed of cyanate ester and 4,4'-diaminodiphenyl sulfone in a mass ratio of 100:6), 12 parts acetone, and silicone resin (KBM-303), wherein the silicone resin accounts for 1.0% of the mass percentage of the epoxy resin adhesive.

[0068] 2) Preparation process of moisture-resistant soft magnetic composite materials:

[0069] Dissolve the above-mentioned resin adhesive and silicone resin in acetone, mix thoroughly, and then add Fe. 92 Si 3.5 Cr 4.5The powder was stirred evenly, granulated, and baked at 60°C for 1 hour to obtain a moisture-resistant soft magnetic composite material.

[0070] 3) Fabrication of integrally molded inductors

[0071] Using powder metallurgy, the coil winding is embedded in the aforementioned moisture-resistant soft magnetic composite material, pressed into shape, and baked to produce an integrally molded inductor with model number 0640-R15. The baking process is as follows: holding at 60℃ for 1 hour, then holding at 80℃ for 1 hour, then holding at 120℃ for 1 hour, and finally holding at 160℃ for 3 hours.

[0072] Performance testing:

[0073] 1) Cracking Test: 100 integrally molded inductors of model 0640-R15 were prepared and placed under conditions of 60℃ and 95%RH for 240 hours to absorb moisture. They were then placed in a reflow oven and left to stand at room temperature for 1 hour. The cracking rate was observed. Cracking was determined by whether the crack length on any face of the integrally molded inductor exceeded half the length of that face. If the crack length on any face exceeded half the length of that face, the product was considered cracked; otherwise, it was considered uncracking. The cracking rate is shown in Table 2. The product appearance is as follows. Figure 2 As shown;

[0074] 2) Relative permeability test: The moisture-resistant soft magnetic composite material prepared above was pressed into a magnetic ring with OD=14mm and ID=8mm under a pressure of 5T, and wound with 13.5 turns of copper wire with a diameter of 0.5mm. Finally, the inductance value was tested with a Tonghui TH-2829 LCR meter, and the relative permeability was finally calculated, as shown in Table 2.

[0075] Example 3

[0076] The preparation method in this embodiment is basically the same as that in Example 1, except that the silicone resin accounts for 2.0% of the mass of the epoxy resin adhesive. The specific steps are as follows:

[0077] 1) Raw materials for preparing moisture-resistant soft magnetic composite materials:

[0078] Take 100 parts by weight of soft magnetic powder Fe 92 Si 3.5 Cr 4.5 3 parts resin adhesive (composed of cyanate ester and 4,4'-diaminodiphenyl sulfone in a mass ratio of 100:6), 12 parts acetone, and silicone resin (KBM-303), wherein the silicone resin accounts for 2.0% of the mass percentage of the epoxy resin adhesive.

[0079] 2) Preparation process of moisture-resistant soft magnetic composite materials:

[0080] Dissolve the above-mentioned resin adhesive and silicone resin in acetone, mix thoroughly, and then add Fe. 92 Si 3.5 Cr 4.5 The powder was stirred evenly, granulated, and baked at 60°C for 1 hour to obtain a moisture-resistant soft magnetic composite material.

[0081] 3) Fabrication of integrally molded inductors

[0082] Using powder metallurgy, the coil winding is embedded in the aforementioned moisture-resistant soft magnetic composite material, pressed into shape, and baked to produce an integrally molded inductor with model number 0640-R15. The baking process is as follows: holding at 60℃ for 1 hour, then holding at 80℃ for 1 hour, then holding at 120℃ for 1 hour, and finally holding at 160℃ for 3 hours.

[0083] Performance testing:

[0084] 1) Cracking Test: 100 integrally molded inductors of model 0640-R15 were prepared and placed under conditions of 60℃ and 95%RH for 240 hours to absorb moisture. They were then placed in a reflow oven and left to stand at room temperature for 1 hour. The cracking rate was observed. Cracking was determined by whether the crack length on any face of the integrally molded inductor exceeded half the length of that face. If the crack length on any face exceeded half the length of that face, the product was considered cracked; otherwise, it was considered uncracking. The cracking rate is shown in Table 2. The product appearance is as follows. Figure 3 As shown;

[0085] 2) Relative permeability test: The moisture-resistant soft magnetic composite material prepared above was pressed into a magnetic ring with OD=14mm and ID=8mm under a pressure of 5T, and wound with 13.5 turns of copper wire with a diameter of 0.5mm. Finally, the inductance value was tested with a Tonghui TH-2829 LCR meter, and the relative permeability was finally calculated, as shown in Table 2.

[0086] Example 4

[0087] The preparation method in this embodiment is basically the same as that in Example 1, except that the soft magnetic powder is carbonyl iron powder. The specific steps are as follows:

[0088] 1) Raw materials for preparing moisture-resistant soft magnetic composite materials:

[0089] By weight, take 100 parts of soft magnetic powder carbonyl iron powder, 3 parts of resin adhesive (composed of cyanate ester and 4,4'-diaminodiphenyl sulfone in a mass ratio of 100:6), 12 parts of acetone, and silicone resin (KBM-303), wherein the silicone resin accounts for 0.3% of the mass percentage of the epoxy resin adhesive.

[0090] 2) Preparation process of moisture-resistant soft magnetic composite materials:

[0091] The above-mentioned resin adhesive and silicone resin were dissolved in acetone, mixed evenly, and then carbonyl iron powder was added and stirred evenly. The mixture was granulated and baked at 60°C for 1 hour to obtain a moisture-resistant soft magnetic composite material.

[0092] Comparative Example 1

[0093] The preparation method of this comparative example is basically the same as that of Example 1, except that no silicone resin was added. The specific steps are as follows:

[0094] 1) Raw materials for preparing moisture-resistant soft magnetic composite materials:

[0095] Take 100 parts by weight of soft magnetic powder Fe 92 Si 3.5 Cr 4.5 3 parts resin adhesive (composed of cyanate ester and 4,4'-diaminodiphenyl sulfone in a mass ratio of 100:6), 12 parts acetone;

[0096] 2) Preparation process of moisture-resistant soft magnetic composite materials:

[0097] Dissolve the above-mentioned resin adhesive in acetone, mix well, and then add Fe. 92 Si 3.5 Cr 4.5 The powder was stirred evenly, granulated, and baked at 60°C for 1 hour to obtain a moisture-resistant soft magnetic composite material.

[0098] 3) Fabrication of integrally molded inductors

[0099] Using powder metallurgy, the coil winding is embedded in the aforementioned moisture-resistant soft magnetic composite material, pressed into shape, and baked to produce an integrally molded inductor with model number 0640-R15. The baking process is as follows: holding at 60℃ for 1 hour, then holding at 80℃ for 1 hour, then holding at 120℃ for 1 hour, and finally holding at 160℃ for 3 hours.

[0100] Performance testing:

[0101] 1) Cracking Test: 100 integrally molded inductors of model 0640-R15 were prepared and placed under conditions of 60℃ and 95%RH for 240 hours to absorb moisture. They were then placed in a reflow oven and left to stand at room temperature for 1 hour. The cracking rate was observed. Cracking was determined by whether the crack length on any face of the integrally molded inductor exceeded half the length of that face. If the crack length on any face exceeded half the length of that face, the product was considered cracked; otherwise, it was considered uncracking. The cracking rate is shown in Table 2. The product appearance is as follows. Figure 4 As shown;

[0102] 2) Relative permeability test: The moisture-resistant soft magnetic composite material prepared above was pressed into a magnetic ring with OD=14mm and ID=8mm under a pressure of 5T, and wound with 13.5 turns of copper wire with a diameter of 0.5mm. Finally, the inductance value was tested with a Tonghui TH-2829 LCR meter, and the relative permeability was finally calculated, as shown in Table 2.

[0103] Comparative Example 2

[0104] The preparation method of this comparative example is basically the same as that of Example 1, except that the silicone resin accounts for 2.1% of the epoxy resin adhesive by mass. The specific steps are as follows:

[0105] 1) Raw materials for preparing moisture-resistant soft magnetic composite materials:

[0106] Take 100 parts by weight of soft magnetic powder Fe 92 Si 3.5 Cr 4.5 3 parts resin adhesive (composed of cyanate ester and 4,4'-diaminodiphenyl sulfone in a mass ratio of 100:6), 12 parts acetone, and silicone resin (KBM-303), wherein the silicone resin accounts for 2.1% of the mass percentage of the epoxy resin adhesive.

[0107] 2) Preparation process of moisture-resistant soft magnetic composite materials:

[0108] Dissolve the above-mentioned resin adhesive in acetone, mix well, and then add Fe. 92 Si 3.5 Cr 4.5 The powder was stirred evenly, granulated, and baked at 60°C for 1 hour to obtain a moisture-resistant soft magnetic composite material.

[0109] 3) Fabrication of integrally molded inductors

[0110] Using powder metallurgy, the coil winding is embedded in the aforementioned moisture-resistant soft magnetic composite material, pressed into shape, and baked to produce an integrally molded inductor with model number 0640-R15. The baking process is as follows: holding at 60℃ for 1 hour, then holding at 80℃ for 1 hour, then holding at 120℃ for 1 hour, and finally holding at 160℃ for 3 hours.

[0111] Performance testing:

[0112] 1) Cracking Test: 100 integrally molded inductors of model 0640-R15 were prepared and placed under conditions of 60℃ and 95%RH for 240 hours to absorb moisture. They were then placed in a reflow oven and left to stand at room temperature for 1 hour. The cracking rate was observed. Cracking was determined by whether the crack length on any face of the integrally molded inductor exceeded half the length of that face. If the crack length on any face exceeded half the length of that face, the product was considered cracked; otherwise, it was considered uncracking. The cracking rate is shown in Table 2. The product appearance is as follows. Figure 5 As shown;

[0113] 2) Relative permeability test: The moisture-resistant soft magnetic composite material prepared above was pressed into a magnetic ring with OD=14mm and ID=8mm under a pressure of 5T, and wound with 13.5 turns of copper wire with a diameter of 0.5mm. Finally, the inductance value was tested with a Tonghui TH-2829 LCR meter, and the relative permeability was finally calculated, as shown in Table 2.

[0114] The formulations of Examples 1-3 and Comparative Examples 1-2 are shown in Table 1:

[0115] Table 1

[0116] No. Soft magnetic powder (parts) Resin binder (parts) Silicone resin (%) Example 1 100 3 0.3 Example 2 100 3 1.0 Example 3 100 3 2.0 Comparative Example 1 100 3 / Comparative Example 2 100 3 2.1

[0117] Note: " / " indicates that the amount of this component added is 0, or no component was added.

[0118] Table 2

[0119] No. Cracking ratio (%) Relative magnetic permeability Example 1 13.5 34.8 Example 2 3.2 34.1 Example 3 0 33.8 Comparative Example 1 40.6 35.2 Comparative Example 2 0 31.8

[0120] The test data in the table above shows that adding silicone resin to the adhesive can improve the moisture resistance of the molded inductor, thereby significantly reducing the degree of surface cracking and the cracking rate after reflow soldering. However, further adjusting the amount of silicone resin added will sacrifice the magnetic properties of the molded inductor.

[0121] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0122] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A moisture-resistant soft magnetic composite material, characterized in that, The components include the following parts by weight: 100 parts of soft magnetic powder 2-5 parts of resin adhesive, wherein the resin adhesive is prepared from raw materials including resin and curing agent, wherein the resin does not include silicone resin, and the curing agent includes one or more of acid anhydride curing agents and amine curing agents. The silicone resin and the resin adhesive are in a mass ratio of (0.3 to 2.0):100, and the silicone resin includes one or more of KBM-303 and KR-48.

2. The moisture-resistant soft magnetic composite material according to claim 1, characterized in that, The mass ratio of the silicone resin to the resin adhesive is (0.3-1.0):

100.

3. The moisture-resistant soft magnetic composite material according to claim 1, characterized in that, The soft magnetic powder includes one or more of the following: carbonyl iron powder, iron-silicon-chromium powder, iron-silicon-aluminum powder, iron-silicon powder, nickel-iron soft magnetic alloy, amorphous iron powder, and nanocrystalline iron powder.

4. The moisture-resistant soft magnetic composite material according to claim 1, characterized in that, The resin includes one or more of epoxy resin, phenolic resin, and cyanate ester.

5. The moisture-resistant soft magnetic composite material according to claim 1, characterized in that, The anhydride curing agent includes one or more of phthalic anhydride, maleic anhydride, and hexahydrophthalic anhydride, and the amine curing agent includes one or more of diaminodiphenylmethane, m-phenylenediamine, and 4,4-diaminophenyl sulfone.

6. A method for preparing a moisture-resistant soft magnetic composite material as described in any one of claims 1 to 5, characterized in that, Includes the following steps: The soft magnetic powder, the resin binder, the silicone resin, and the organic solvent are mixed and granulated.

7. The method for preparing the hygroscopically resistant soft magnetic composite material according to claim 6, characterized in that, The organic solvent includes one or more of acetone, N,N-dimethylformamide, and methyl acetate.

8. The method for preparing the moisture-resistant soft magnetic composite material according to claim 6 or 7, characterized in that, It also includes a drying step, wherein the drying temperature is 40°C to 80°C.

9. A molded inductor, characterized in that, It includes the moisture-resistant soft magnetic composite material as described in any one of claims 1 to 5 and the coil winding embedded in the moisture-resistant soft magnetic composite material.

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