Coil encapsulation core and coil components

Abstract

This invention provides a coil-encapsulated core and coil component that can simultaneously achieve improved insulation and improved initial permeability. One coil-encapsulated core comprises magnetic powder and resin and encapsulates a coil made of conductor, and also contains a modifier.

Description

Technical Field

[0001] This invention relates to coil-encapsulated magnetic cores and coil components, and particularly to coil components preferred for use as power supply inductors, such as choke coils for power supply smoothing circuits in electronic devices, and coil-encapsulated magnetic cores contained in such coil components. Background Technology

[0002] In the field of consumer and industrial electronic equipment, surface-mount coil components are often used as inductors for power supplies. This is because surface-mount coil components are small, thin, and have excellent electrical insulation properties, and can be manufactured at low cost. One specific structure of surface-mount coil components is the planar coil structure that utilizes printed circuit board technology.

[0003] In such coil components, the electromagnetic properties of the coil core encapsulated within the coil (conductor) have a significant impact on the electromagnetic properties of the coil component. For example, in order to reduce the magnetic cohesion between magnetic powders, a technique has been proposed to add a dispersant to the coil core encapsulated within the coil (see Patent Document 1).

[0004] However, in the existing technology of adding dispersants to the magnetic core of the coil, if the amount added is small, there is a problem that the insulation between the magnetic powders becomes insufficient; if the amount added is too large, there is a problem that the magnetic properties are reduced.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 11-126721 Summary of the Invention

[0008] The present invention was developed in view of this practical situation, and its purpose is to provide a coil-encapsulated magnetic core and coil components that can simultaneously improve insulation and initial permeability.

[0009] To achieve the above objectives, the coil involved in this invention is encapsulated in a magnetic core.

[0010] It is a coil core containing magnetic powder and resin and encapsulated within a coil made of conductor.

[0011] Contains modifiers.

[0012] The coil-encapsulated magnetic core of the present invention contains a modifier, which prevents the magnetic powder from contacting each other, thereby achieving both improved insulation and improved initial permeability.

[0013] Alternatively, the modifier may be a substance having a polycaprolactone structure.

[0014] Modifiers with a polycaprolactone structure significantly improve the insulation and initial permeability of coils encapsulated in the magnetic core.

[0015] Alternatively, for example, the content of the modifier may be 0.1 to 0.8 wt% relative to the total amount of the coil encapsulated in the magnetic core.

[0016] By setting the content of the modifier within the aforementioned range, the effect of improving the insulation of the coil-encapsulated core and the initial permeability is particularly significant.

[0017] Alternatively, for example, the magnetic powder may also contain a soft magnetic metal.

[0018] By using magnetic powder containing soft magnetic metals, the initial permeability of the coil encapsulated in the magnetic core can be increased.

[0019] Alternatively, for example, the magnetic powder may also be part of an insulating coating particle consisting of soft magnetic powder made of soft magnetic metal and coated with an insulating coating containing SiO2.

[0020] By incorporating magnetic powder as part of the insulating coating particles, the insulation of the coil encapsulated in the magnetic core can be further improved.

[0021] Alternatively, for example, the magnetic powder may also consist of at least two types of magnetic powder with different particle sizes, namely small-diameter powder and large-diameter powder.

[0022] By using two or more types of magnetic powder, such as three, the density of the coil encapsulated in the magnetic core is increased, which can improve the initial permeability.

[0023] Furthermore, the coil component according to the present invention has:

[0024] A coil, which is made of conductors;

[0025] The coil is encapsulated in a magnetic core, which contains magnetic powder and resin and is encapsulated within the coil.

[0026] A pair of external terminals, which are electrically connected to the coil,

[0027] The coil encapsulated in the magnetic core contains a modifier.

[0028] The coil component of the present invention contains a modifier in the coil-encapsulated magnetic core, which prevents the magnetic powder from contacting each other. As a result, both the insulation of the coil-encapsulated magnetic core and the initial permeability are improved. Attached Figure Description

[0029] Figure 1 This is a perspective view of the coil component according to the first embodiment of the present invention.

[0030] Figure 2 yes Figure 1An exploded perspective view of the coil component shown.

[0031] Figure 3 It is along Figure 1 The cross-sectional view of line III-III shown.

[0032] Figure 4 It is along Figure 1 The cross-sectional view of line IV-IV is shown.

[0033] Figure 5 This is a schematic diagram of magnetic powder with an insulating coating.

[0034] Figure 6 It is a graph showing the measurement results related to the amount of modifier added and the insulation breakdown strength of the coil encapsulated in the magnetic core.

[0035] Figure 7 It is a graph showing the measurement results related to the amount of modifier added and the initial permeability of the coil encapsulated in the magnetic core.

[0036] Figure 8 It is a graph showing the results of the measurements related to the amount of modifier added and the three-point bending strength of the coil encapsulated in the magnetic core.

[0037] Figure 9 This is a cross-sectional view of the coil component according to the second embodiment of the present invention.

[0038] Explanation of symbols

[0039] 2. 102…coil components

[0040] 4…External terminal

[0041] 4a…inner layer

[0042] 4b…outer layer

[0043] 10…Main Body

[0044] 10a… Upper surface

[0045] 10b…lower surface

[0046] 17… Coil sealed into magnetic core

[0047] 11…Insulating substrate

[0048] 12, 13… Internal conductor paths

[0049] 12a, 13a... connection terminals

[0050] 12b, 13b... lead wire contact section

[0051] 14… Protective insulation layer

[0052] 15…upper core

[0053] 15a…Midfoot

[0054] 15b…side foot

[0055] 16…lower core

[0056] 18… Through-hole conductor

[0057] 20…Magnetic powder

[0058] 22… Insulating coating particles

[0059] 22…Insulating coating

[0060] 11i…through hole

[0061] C1~C4… Coil conductor pattern

[0062] 111, 112… Magnetic layers

[0063] 117… Coil sealed in magnetic core

[0064] 104, 105…external terminals

[0065] 140~144… interlayer insulation

[0066] 161, 162... Electrode layers. Detailed Implementation

[0067] The present invention will now be described based on the embodiments shown in the accompanying drawings.

[0068] First Implementation Method

[0069] As one embodiment of the coil component of the present invention, examples can be given. Figures 1-4 The coil component 2 is shown. (As shown) Figure 1 As shown, the coil component 2 has a rectangular flat body 10 and a pair of external terminals 4, 4 respectively mounted at both ends of the body 10 in the X-axis direction. The external terminals 4, 4 cover the X-axis end face of the body 10, and partially cover the upper surface 10a and lower surface 10b of the body 10 in the Z-axis direction at their attachments to the X-axis end face. In addition, the external terminals 4, 4 also partially cover a pair of side faces of the body 10 in the Y-axis direction.

[0070] like Figure 2 As shown, the main body 10 has a coil-sealed magnetic core 17 composed of an upper core 15 and a lower core 16, and has internal conductor passages 12 and 13 and a through-hole conductor 18 (see reference). Figure 3 The coil 19. In addition, the main body 10 has an insulating substrate 11 at its central part in the Z-axis direction.

[0071] The insulating substrate 11 is preferably made of a common printed substrate material in which epoxy resin is impregnated with glass cloth, but there is no particular limitation.

[0072] In addition, in this embodiment, the insulating substrate 11 is rectangular, but it can also be other shapes. The method of forming the insulating substrate 11 is not particularly limited, and it can be formed by injection molding, doctor blade method, screen printing, etc.

[0073] Furthermore, an internal electrode pattern consisting of circular spiral internal conductor passages 12 is formed on the upper surface (a main surface) of the insulating substrate 11 in the Z-axis direction. The internal conductor passages 12 form part of the coil 19. There are no particular limitations on the material of the internal conductor passages 12; for example, good conductors such as Cu and Au can be used.

[0074] A connection end 12a is formed at the inner peripheral end of the spiral-shaped internal conductor passage 12. In addition, a lead wire contact portion 12b is formed at the outer peripheral end of the spiral-shaped internal conductor passage 12, exposed along the X-axis direction end (X negative direction end) of the main body portion 10.

[0075] An internal electrode pattern consisting of spiral internal conductor passages 13 is formed on the lower surface (another main surface) of the insulating substrate 11 in the Z-axis direction. The internal conductor passages 13 form part of the coil 19. In addition, there are no particular limitations on the material of the internal conductor passages 13, and they are the same as those of the internal conductor passages 12. For example, good conductors such as Cu and Au can be used.

[0076] A connection end 13a is formed at the inner peripheral end of the spiral-shaped internal conductor passage 13. In addition, a lead wire contact portion 13b is formed at the outer peripheral end of the spiral-shaped internal conductor passage 13, so as to expose the end (positive X direction end) along the other X-axis direction of the main body portion 10.

[0077] like Figure 3 As shown, connection terminals 12a and 13a are formed on opposite sides of the insulating substrate 11 in the Z-axis direction, and at the same position in the X-axis and Y-axis directions. Therefore, connection terminals 12a and 13a are electrically connected via through-hole conductors 18 embedded in through-holes 11i formed in the insulating substrate 11. That is, the spiral-shaped internal conductor passage 12 and the same spiral-shaped internal conductor passage 13 are electrically connected in series via the through-hole conductors 18.

[0078] like Figure 2 As shown, the spiral-shaped internal conductor passage 12, viewed from the upper surface 10a side (positive X-axis direction side) of the main body 10, forms a spiral that rotates counterclockwise from the lead contact portion 12b at the outer peripheral end to the connecting end 12a at the inner peripheral end.

[0079] In contrast, the spiral-shaped internal conductor passage 13, viewed from the upper surface 10a side (positive X-axis direction side) of the main body 10, forms a spiral that rotates counterclockwise from the connection end 13a, which is the inner peripheral end, to the lead contact part 13b, which is the outer peripheral end.

[0080] Therefore, the direction of the magnetic flux generated by flowing current through the spiral internal conductor paths 12 and 13 is consistent in both internal conductor paths 12 and 13. The magnetic flux generated in the spiral internal conductor paths 12 and 13 overlaps and reinforces each other, resulting in a large inductance. Thus, the internal conductor paths 12 and 13, which are made of conductors, and the through-hole conductor 18 constitute the coil 19.

[0081] like Figure 2 As shown, the upper core 15 has a cylindrical central foot 15a protruding downward in the Z-axis direction at the center of the rectangular flat core body. In addition, the upper core 15 has plate-shaped side feet 15b protruding downward in the X-axis direction at both ends of the rectangular flat core body in the Y-axis direction.

[0082] The lower core 16 has the same rectangular flat plate shape as the core body of the upper core 15. The middle foot 15a and the side foot 15b of the upper core 15 are connected to the central part and the end in the Y-axis direction of the lower core 16 respectively and integrated.

[0083] In addition, Figure 2 In this design, the coil-encapsulated magnetic core 17 is depicted separately as an upper core 15 and a lower core 16, but they can also be integrated by the core composition described below. Additionally, the middle leg 15a and / or side leg 15b formed on the upper core 15 can also be formed on the lower core 16. In either case, the coil-encapsulated magnetic core 17 constitutes a completely closed magnetic circuit, within which there are no gaps.

[0084] like Figure 2 As shown, a protective insulating layer 14 is interposed between the upper core 15 and the internal conductor passage 12 to insulate them. Additionally, a rectangular sheet-like protective insulating layer 14 is interposed between the lower core 16 and the internal conductor passage 13 to insulate them. A circular through-hole 14a is formed in the center of the protective insulating layer 14. Furthermore, a circular through-hole 11h is also formed in the center of the insulating substrate 11. The middle leg portion 15a of the upper core 15 extends downwards towards the lower core 16 through these through-holes 14a and 11h and connects to the center of the lower core 16.

[0085] like Figure 4As shown, in this embodiment, the external terminal 4 has an inner layer 4a that contacts the X-axis end face of the main body 10 and an outer layer 4b formed on the surface of the inner layer 4a. The inner layer 4a also covers a portion of the upper surface 10a and lower surface 10b of the main body 10 at its X-axis end face attachment, and the outer layer 4b covers its outer surface. Figure 4 As shown, a pair of external terminals 4, 4 are electrically connected to the coil 19 encapsulated in the magnetic core 17 via lead contacts 12b, 13b.

[0086] Here, the coil-encapsulated magnetic core 17 in the main body 10 includes magnetic powder and resin. Additionally, the coil-encapsulated magnetic core 17 includes a modifier. That is, the coil-encapsulated magnetic core 17 is composed of a magnetic material containing magnetic powder, resin, and a modifier.

[0087] The magnetic powder of this embodiment will be described below.

[0088] The magnetic powder in this embodiment, for example, has at least two types of magnetic powder with different particle sizes (D50), namely small-diameter powder and large-diameter powder. However, the magnetic powder constituting the coil-encapsulated magnetic core 17 is not limited to this, and may also have one or more types of magnetic powder with different particle sizes. Here, D50 refers to the diameter of the particle size with a cumulative value of 50%.

[0089] Therefore, among the two types of magnetic powder, the magnetic powder with a larger D50 is designated as the large-diameter powder, and the magnetic powder with a smaller D50 than the large-diameter powder is designated as the small-diameter powder. The magnetic powder preferably contains a soft magnetic metal. In the magnetic powder of this embodiment, the large-diameter powder is composed of iron or an iron-based alloy, and the small-diameter powder is composed of a Ni-Fe alloy, both of which are composed of soft magnetic metals. However, the small-diameter powder may also be composed of an iron-based alloy. Alternatively, the magnetic powder may also be a ferrite powder.

[0090] The iron-based alloy in this embodiment refers to an alloy containing 80% by weight or more iron. Furthermore, if the iron content is 80% by weight or more, there are no particular restrictions on the type of large-diameter powder; in addition to Fe-based amorphous powder and carbonyl iron powder (pure iron powder), various Fe-based alloys and nanocrystals can also be used.

[0091] The Ni-Fe alloy in this embodiment refers to an alloy containing 28% by weight or more Ni and the remainder consisting of Fe and other elements. The content of other elements is not particularly limited, but can be set to 8% by weight or less when the Ni-Fe alloy as a whole is 100% by weight.

[0092] In addition, the magnetic powder in this embodiment can also be as follows: Figure 5The soft magnetic powder 20 shown is composed of a soft magnetic metal and is part of an insulating coating particle 23 covered by an insulating coating 22 containing SiO2. Furthermore, "covered by an insulating coating" means that more than 50% of the powder particles in the powder are covered by the insulating coating.

[0093] The particle size of insulating coating particles 23 is Figure 5 The length of d1. Additionally... Figure 5 The length of d2, which is the maximum thickness of the insulating coating 22 in the insulating coating particle 23, becomes the thickness of the insulating coating 22 in the insulating coating particle 23. Furthermore, the insulating coating 22 does not necessarily need to cover the entire surface of the soft magnetic powder 20. Soft magnetic powder 20 whose surface is covered by the insulating coating 22 by more than 50% is considered as the insulating coating particle 23.

[0094] The magnetic powder of this embodiment has the above-described structure, and a coil component 2 with excellent initial permeability, core loss, withstand voltage, insulation resistance and DC overlap characteristics can be obtained.

[0095] The magnetic powder of this embodiment will be described in more detail below.

[0096] The D50 of the large-diameter powder (or, in the case where the large-diameter powder is part of the insulating coating particles 23, the D50 of the insulating coating particles) is not particularly limited, but is preferably 10–40 μm, more preferably 15–30 μm. The D50 of the small-diameter powder (or, in the case where the small-diameter powder is part of the insulating coating particles 23, the D50 of the insulating coating particles) is not particularly limited, but is preferably 10–40 μm, more preferably 15–30 μm. Figure 5 In the case of a portion of the insulating coating particles 23 shown, the D50 of the insulating coating particles 23 is not particularly limited, but is preferably 0.5 to 1.5 μm, more preferably 0.5 to 1.0 μm (excluding 1.0 μm), and even more preferably 0.7 to 0.9 μm.

[0097] The particle size inhomogeneity of the preferred small-diameter powder is relatively small. Specifically, the D90 (the diameter of 90% of the particle size cumulatively) of the small-diameter powder is preferably 4.0 μm or less. Furthermore, when the small-diameter powder is part of the insulating coating particles 23, the D90 is the insulating coating particles themselves. With a D90 of 4.0 μm or less, the initial permeability is increased and the core loss is reduced.

[0098] Large-diameter and small-diameter powders are preferably spherical. Specifically, in this embodiment, spherical means having a sphericity of 0.9 or higher. Furthermore, sphericity can be measured using an image-based particle size analyzer.

[0099] The Ni content in the Ni-Fe alloy is preferably 40-85%, and particularly preferably 75-82%. By setting the Ni content within the above range, the initial permeability is increased and the core loss is reduced. Furthermore, the above-mentioned content is a weight ratio.

[0100] The proportion of small-diameter powder in the total magnetic powder is preferably 5-25%, more preferably 6.5-20%. By setting the proportion of small-diameter powder within the above range, the initial permeability is increased and the core loss is reduced. Furthermore, the above proportions are by weight.

[0101] The thickness of the insulating coating 22 is not particularly limited, but it is preferable to set the average thickness of the insulating coating 22 for small-diameter powders to be 5 to 45 nm, and particularly preferably 10 to 35 nm. In addition, the thickness of the insulating coating 22 can be the same for both small-diameter and large-diameter powders, or the thickness of the insulating coating 22 for large-diameter powders can be thicker than that for small-diameter powders.

[0102] The material of the insulating coating 22 is not particularly limited, and insulating coatings commonly used in this art can be used. Preferably, it comprises a glass film composed of SiO2 or a phosphate-formed film containing phosphates, and particularly preferably, a glass film composed of SiO2. Furthermore, the method of applying the insulating coating is not particularly limited, and methods commonly used in this art can be employed.

[0103] Furthermore, the magnetic powder of this embodiment may also include medium-diameter powder with a D50 smaller than that of large-diameter powder and a D50 larger than that of small-diameter powder. That is, the magnetic powder may also include at least three types of magnetic powder with different particle sizes, namely small-diameter powder, medium-diameter powder, and large-diameter powder.

[0104] In this case, the medium-diameter powder is preferably coated with an insulating coating in the same way as the large-diameter and small-diameter powders.

[0105] The D50 of the medium diameter powder (when the medium diameter powder is part of the insulating coating particles 23) is Figure 5 The D50 of the insulating coating particles 23 shown is preferably 3.0 to 10 μm. When the D50 of the medium-diameter powder is within the above-mentioned range, the magnetic permeability is improved.

[0106] There are no particular restrictions on the material of medium-diameter powder, but it is preferred to use the same material as large-diameter powder, which is made of iron or iron-based alloy.

[0107] Furthermore, regarding the proportion of each powder in the total magnetic powder, it is preferable that the proportion of large-diameter powder is 70-80%, the proportion of medium-diameter powder is 10-15%, and the proportion of small-diameter powder is 10-15%. By adopting the above proportions, core loss is reduced and magnetic permeability is increased.

[0108] In this embodiment, the particle size of the large-diameter powder, medium-diameter powder, and small-diameter powder, as well as the thickness of the insulating coating, are measured using a transmission electron microscope. Furthermore, the particle size and material of the large-diameter powder, medium-diameter powder, and small-diameter powder in this embodiment are generally not substantially changed during the manufacturing process of the coil component 2.

[0109] As the magnetic powder of this embodiment, by using the magnetic powder with the insulating coating described above, a high-density coil-insertion core 17 can be formed under low pressure or non-pressure forming, and a coil-insertion core 17 with high permeability and low loss can be achieved.

[0110] Furthermore, it is believed that a high-density coil-insertion core 17 can be obtained because medium-diameter powder and / or small-diameter powder fill the gaps created when only large-diameter powder is used. Additionally, to further increase the density of the coil-insertion core 17, it is considered to use only small-diameter powder instead of medium-diameter powder. By omitting medium-diameter powder, a coil-insertion core 17 with higher permeability is sometimes obtained compared to the case where medium-diameter powder is used.

[0111] In contrast, when using both medium-diameter and small-diameter powders, even if various conditions such as changes in the Ni content of the small-diameter powder change, a coil-sealed magnetic core 17 with minimal changes in characteristics corresponding to these changes can be obtained. Therefore, when using both medium-diameter and small-diameter powders, the manufacturing stability of the coil-sealed magnetic core 17 is higher than that when using only small-diameter powder.

[0112] The content of magnetic powder encapsulated in the coil core 17 is preferably 90-99% by weight, more preferably 95-99% by weight. If the amount of magnetic powder relative to the resin or modifier is reduced, the saturation magnetic flux density and permeability decrease; conversely, if the amount of magnetic powder is increased, the saturation magnetic flux density and permeability increase. Therefore, the saturation magnetic flux density and permeability can be adjusted by the amount of magnetic powder.

[0113] The resin contained in the coil encapsulated in the magnetic core 17 functions as an insulating and bonding material. Liquid epoxy resin or powdered epoxy resin is preferably used as the resin material. Furthermore, the resin content is preferably 1 to 10% by weight, more preferably 1 to 5% by weight. Additionally, a resin solution is preferably used when mixing the magnetic powder, resin, and modifier to obtain the magnetic core composition. The solvent for the resin solution is not particularly limited.

[0114] The modifier contained in the coil encapsulated in the magnetic core 17 inhibits the contact between the magnetic powder particles. The preferred material for the modifier is a substance having a polycaprolactone structure. Examples of substances having a polycaprolactone structure include polycaprolactone diol, polycaprolactone tetraol, and other polyurethane raw materials, or a portion of polyester.

[0115] The content of the modifier in the coil-encapsulated magnetic core 17 is preferably 0.1 to 0.8 wt% relative to the total amount of the coil-encapsulated magnetic core 17. By setting the content of the modifier to a predetermined level or higher, an effective improvement in insulation and initial permeability can be expected. Furthermore, by setting the content of the modifier to a predetermined level or lower, a decrease in three-point bending strength can be prevented. In addition, in the coil-encapsulated magnetic core 17, the resin reacts thermally and acts as a binder, whereas the modifier does not exhibit the same reaction as the resin. Furthermore, existing dispersants do not achieve the same effect as the modifier. This is presumably because the modifier is adsorbed onto the entire surface of the magnetic powder by coating it, whereas the dispersant has sites adsorbed onto the magnetic powder surface (adsorption groups) and sites not adsorbed onto the magnetic powder surface, which has an impact.

[0116] The manufacturing method of coil component 2 will be described below.

[0117] First, spiral-shaped internal conductor pathways 12 and 13 are formed on the insulating substrate 11 by plating. The plating conditions are not particularly limited. Alternatively, they can be formed using methods other than plating.

[0118] Next, a protective insulating layer 14 is formed on both sides of the insulating substrate 11, on which the internal conductor passages 12 and 13 are formed. The method for forming the protective insulating layer 14 is not particularly limited. For example, the protective insulating layer 14 can be formed by immersing the insulating substrate 11 in a resin solution diluted with a high-boiling-point solvent and then drying it.

[0119] Next, a formation of Figure 2 The coil, consisting of the upper core 15 and the lower core 16 shown, is encapsulated in a magnetic core 17. For this purpose, the aforementioned magnetic core composition is coated onto the surface of an insulating substrate 11 on which a protective insulating layer 14 is formed. The coating method is not particularly limited and is typically performed by printing.

[0120] Next, the solvent components of the printed magnetic core composition are evaporated, forming a coil that is sealed into the magnetic core 17, thus forming... Figure 1 The main body 10 is shown.

[0121] In addition, the density of the main body 10 and the coil-encapsulated magnetic core 17 is increased. There is no particular limitation on the method for increasing the density of the main body 10 and the coil-encapsulated magnetic core 17; for example, a stamping process can be used.

[0122] Then, the upper surface 10a and lower surface 10b of the main body 10 are ground to make the main body 10 meet the specified thickness. Then, it is heat-cured to cross-link the resin. There is no particular limitation on the grinding method; for example, a method using a fixed grinding stone can be used. In addition, there are no particular limitations on the temperature and time of heat curing, as long as they are appropriately controlled according to the type of resin, etc.

[0123] Then, the main body 10 is cut into single pieces. There is no particular limitation on the cutting method; for example, various cutting methods can be described.

[0124] The above methods are used to obtain the formation Figure 1 The main body 10 is shown before the external terminal 4. Furthermore, in the state before cutting, the main body 10 is integrally connected in the X-axis direction and the Y-axis direction.

[0125] In addition, after cutting, the monolithic main body 10 is etched. There are no particular limitations on the conditions for the etching process.

[0126] Next, electrode material is applied to both ends of the etched main body 10 in the X-axis direction to form an inner layer 4a. As the electrode material, a thermosetting resin containing conductive powder, such as Ag powder, can be used, which contains conductive powder such as epoxy powder in a thermosetting resin, similar to the epoxy resin used in the magnetic core composition described above.

[0127] Next, the electrode paste coated to form the inner layer 4a is subjected to terminal plating via barrel plating to form the outer layer 4b. The outer layer 4b can also be a multilayer structure with two or more layers. There are no particular limitations on the formation method and material of the outer layer 4b; for example, it can be formed by plating Ni on the inner layer 4a and then plating Sn on the Ni plating. The coil component 2 can be manufactured using the above method.

[0128] In this embodiment, the coil-encapsulated magnetic core 17 of the main body 10 contains magnetic powder and resin. Therefore, by creating a state in which tiny gaps are formed between the magnetic powder particles, the saturation magnetic flux density is increased. Thus, magnetic saturation can be prevented by not forming an air gap between the upper core 15 and the lower core 16. Therefore, it is not necessary to perform high-precision machining of the magnetic core to form the gap.

[0129] Furthermore, in the coil component 2 of this embodiment, by forming it as an assembly on the substrate surface, the positional accuracy of the coil 19 is very high, allowing for miniaturization and thinning. By using a soft magnetic metal material as the magnetic powder, the DC overlap characteristic can be improved compared to ferrite, eliminating the need for magnetic gap formation.

[0130] Furthermore, in coil component 2, a substance with a polycaprolactone structure, i.e., a modifier, is included in the core composition and the coil-encapsulated core 17. Therefore, the contact between the magnetic powders in the coil-encapsulated core 17 can be suppressed. As a result, the insulation and initial permeability of the coil-encapsulated core 17 can be improved.

[0131] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the present invention. For example, even... Figures 1-4Any coil component other than the coil component shown, as long as the coil core encapsulated in coil 19 contains magnetic powder, resin and modifier, is a coil component of the present invention.

[0132] Second Implementation Method

[0133] Figure 9 This is a cross-sectional view showing the coil component 102 according to the second embodiment of the present invention. The coil component 102, a portion of which has a structure similar to... Figure 2 The coil component 2 shown is different and includes: a coil composed of multiple coil conductor patterns C1, C2, C3, and C4; a coil-encapsulated magnetic core 117 composed of magnetic body layers 111 and 112 containing magnetic powder and resin; and a pair of external terminals 104 and 104 electrically connected to the coil. Additionally, the coil component 102 has interlayer insulating layers 140, 141, 142, 143, and 144, and electrode layers 161 and 162.

[0134] Figure 9 The coil conductor patterns C1 to C4 shown are each formed into a coil pattern with two turns wound in a spiral shape. Each coil conductor pattern C1 to C4 is stacked through interlayer insulating layers 141 to 144. Adjacent coil conductor patterns C1 to C4 are connected to each other through through-hole conductors in the interlayer insulating layers 141 to 143. Thus, the coil conductor patterns C1 to C4 form an interconnected coil.

[0135] The coil conductor patterns C1 to C4 and the through-hole conductors are made of good conductors such as Cu, and the interlayer insulation layers 141 to 143 are formed of resin, for example.

[0136] The coil, consisting of magnetic layers 111 and 112, is sealed within the magnetic core 117. Figure 2 The coil shown, consisting of an upper core 15 and a lower core 16, is encased in the same material as the magnetic core 17, forming a closed magnetic circuit. Furthermore, with... Figure 2 The coil-encapsulated magnetic core 117 shown is the same as that in the coil-encapsulated magnetic core 117, which is composed of magnetic body layers 111 and 112 and contains a modifier. Furthermore, the magnetic powder, resin and modifier contained in the magnetic body layers 111 and 112 can be the same as those contained in the coil-encapsulated magnetic core 17 of the first embodiment.

[0137] A pair of external terminals 104 formed on the side of the coil component 102 are connected to the coil (coil conductor patterns C1 to C4) encapsulated in the coil core 117 via electrode layers 161 and 162. The electrode patterns 161 and 162 are made of Cu, for example, and the external terminals 104 are made of a laminated film of Ni and Sn, for example, but are not limited to these.

[0138] The coil component 102 in the second embodiment is manufactured as follows: Resin layers forming interlayer insulating layers 140-144 and conductor layers forming coil conductor patterns C1-C4 and electrode layers 161, 162 are alternately layered on a predetermined support substrate. Unnecessary portions (e.g., portions corresponding to the middle leg portion 112a of the magnetic body layer 112) of the resin are then removed. The same core composition as used in the first embodiment for manufacturing the coil core 17 is inserted into the space where the resin has been removed. After forming the magnetic body layer 112, the support substrate is removed, and the same core composition is used to further form the magnetic body layer 111.

[0139] Next, the resin contained in the magnetic layers 111 and 112 is cross-linked by heat curing, and then cut into single pieces to expose the electrode layers 161 and 162. External terminals 104 are then formed on the electrode layers 161 and 162, resulting in... Figure 9 The coil component 102 is shown. Furthermore, the interlayer insulating layers 140-144 can be formed by spin coating or patterning by photolithography. Additionally, the conductor layers that form the coil conductor patterns C1-C4 and the electrode layers 161, 162 can be formed by film formation using thin film methods such as sputtering or film growth using electrolytic plating.

[0140] Figure 9 The coil component 102 shown is the same as the coil component 2 in the first embodiment. It contains a substance with a polycaprolactone structure, i.e., a modifier, in the core composition and the coil-encapsulated core 117. Therefore, the adsorption of magnetic powder within the coil-encapsulated core 117 is suppressed. This improves the insulation and initial permeability of the coil-encapsulated core 117. Furthermore, regarding the common parts with the coil component 2, the coil component 102 exhibits the same effects as the coil component 2.

[0141] Example

[0142] The present invention will now be described based on embodiments. However, the present invention is not limited to these embodiments.

[0143] Ten samples were prepared with modifier contents in the coil-encapsulated magnetic core 17 at 0 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%, 1.0 wt%, and 1.2 wt% relative to the total amount of the coil-encapsulated magnetic core 17. For each sample, the initial permeability μi, insulation breakdown strength (voltage), and three-point bending strength were evaluated. As a modifier, a substance with a polycaprolactone structure (trade name BYK-LP C 22435 (manufacturer: BYK)) was used.

[0144] The components in each sample, excluding the modifier contained in the coil-encapsulated magnetic core 17, are common, as shown below.

[0145] <Magnetic Powder>

[0146] (1) Large diameter powder: Fe-based amorphous powder (D50: 26μm)

[0147] (2) Medium diameter powder: carbonyl iron powder (D50: 4.0μm)

[0148] (3) Small diameter powder: Ni-Fe alloy powder (Ni content: 78% by weight, D50: 0.9μm, D90: 1.2μm)

[0149] The magnetic powder is used as a magnetic powder in the coil encapsulation core 17, with a mixing ratio of 80% large-diameter powder, 10% medium-diameter powder, and 10% small-diameter powder. For the large-diameter powder, medium-diameter powder, and small-diameter powder, an insulating film composed of glass containing SiO2 is formed with a film thickness of 20 nm or more.

[0150] <Resin>

[0151] Epoxy resin

[0152] Ten magnetic core compositions were prepared by mixing epoxy resin and modifier relative to magnetic powder in the proportions shown in Table 1, with further addition of solvent. Using the prepared magnetic core compositions, specimens were fabricated for determining insulation breakdown strength, initial permeability, and three-point bending strength, respectively.

[0153] [Table 1]

[0154] Magnetic powder Epoxy resin Modifier Mix ratio 1 98 2.0 0 Mix ratio 2 98 1.9 0.1 Mix ratio 3 98 1.8 0.2 Mixing ratio 4 98 1.7 0.3 Mix ratio 5 98 1.6 0.4 Mix ratio 6 98 1.5 0.5 Mixing ratio 7 98 1.4 0.6 Mixture ratio 8 98 1.2 0.8 Mix ratio 9 98 1.0 1.0 Mixture ratio 10 98 0.8 1.2

[0155] (Unit: wt%)

[0156] <Insulation breaking strength>

[0157] In the insulation breakdown strength test, a sample with a coil core of 0.65 mm thickness was prepared and cured using the above-mentioned magnetic composition. In the insulation breakdown strength test, the voltage when a DC current of 2 mA flows through the prepared sample in the thickness direction was measured, and the insulation breakdown strength (V / mm) was calculated based on the measured voltage. Figure 6 This is a graph showing the results of measuring the insulation breakdown strength of 10 samples with different contents of modifier.

[0158] like Figure 6As shown, the samples containing the modifier showed an increase in insulation breakdown strength compared to the samples without the modifier (0 wt%). However, among the 10 samples, the sample with 0.4 wt% modifier showed the best insulation breakdown strength, with significant improvements observed in samples with 0.1–0.8 wt% modifier and particularly significant improvements in samples with 0.2–0.6 wt%.

[0159] <Initial permeability>

[0160] In the experiment on initial permeability, for Figure 2 The prepared magnetic core composition is coated onto an insulating substrate 11, which has a protective insulating layer 14 and internal conductor pathways 12 and 13. This is then shaped and cured to form a main body 10. External terminals 4, each 1.3 mm wide, are provided at both ends of the main body 10, ready for use with… Figures 1-4 The sample is identical to coil component 2 shown (with different contents of modifier). Figure 7 This is a graph showing the results of measuring the initial magnetic permeability μi of 10 samples with different contents of modifier.

[0161] like Figure 7 As shown, the samples containing the modifier showed an increase in initial permeability μi compared to the samples without the modifier (0 wt%). However, among the 10 samples, the initial permeability μi was best with a modifier content of 0.6 wt%, and the improvement was significant in samples with a modifier content of 0.2–0.8 wt%, with a particularly significant improvement observed in samples with a modifier content of 0.3–0.6 wt%.

[0162] <Three-point bending strength>

[0163] In the three-point bending strength test, a specimen was prepared using the prepared core composition, forming a coil sealed within the core with a width of 5 mm, a length of 30 mm, and a thickness of 0.7 mm. The three-point bending strength of each specimen at room temperature was measured using an automated precision universal tensile testing machine (Shimadzu AGS-X), with varying modifier content. The testing conditions were set as follows: force sensor capacity 5 kN, distance between support points 10 mm, and test speed 1 mm / min. The three-point bending strength σ was calculated using Equation 1 based on the load W (N) at fracture measured by the automated precision universal tensile testing machine.

[0164] σ=(3×L×W) / (2×b×h^2) (Formula 1)

[0165] Furthermore, in Equation 1, L is the distance between the fulcrums, b is the width of the specimen, and h is the thickness of the specimen. Figure 8This is a graph showing the results of measuring the three-point bending strength of 10 samples with different modifier contents.

[0166] like Figure 8 As shown, the samples containing the modifier showed a slight tendency for a decrease in three-point flexural strength compared to the samples without the modifier (0 wt%). However, for samples with a modifier content of 0.8 wt% or less, sufficient three-point flexural strength was confirmed to be above 60 MPa.

Claims

1. A coil sealed in a magnetic core, wherein, It is a coil core containing magnetic powder and resin and encapsulated within a coil made of conductor. The coil encapsulated in the magnetic core contains a modifier. The modifier is a substance with a polycaprolactone structure. The content of the magnetic powder is 90-99 wt% of the magnetic core into which the coil is sealed. The content of the modifier is 0.3~0.8 wt% relative to the total amount of the coil encapsulated in the magnetic core.

2. The coil-encased magnetic core according to claim 1, characterized in that, The content of the modifier is 0.3 to 0.6 wt% relative to the total amount of the coil encapsulated in the magnetic core.

3. The coil-encased magnetic core according to claim 1, wherein, The magnetic powder contains a soft magnetic metal.

4. The coil-encased magnetic core according to claim 3, wherein, The magnetic powder is a soft magnetic powder made of soft magnetic metal, which is part of the insulating coating particles covered by an insulating coating containing SiO2.

5. The coil-encased magnetic core according to claim 1, wherein, The magnetic powder comprises small-diameter powder and large-diameter powder, which are at least two types of magnetic powders with different particle sizes.

6. A coil component, wherein, have: A coil, which is made of conductors; A coil is encapsulated within a magnetic core, which comprises magnetic powder and resin and is encapsulated within the coil; and A pair of external terminals, which are electrically connected to the coil, The coil encapsulated in the magnetic core contains a modifier. The modifier is a substance with a polycaprolactone structure. The content of the magnetic powder is 90-99 wt% of the magnetic core into which the coil is sealed. The content of the modifier is 0.3~0.8 wt% relative to the total amount of the coil encapsulated in the magnetic core.

7. The coil-encased magnetic core according to claim 1, characterized in that, The content of the modifier is 0.4~0.6 wt% of the total amount of the coil encapsulated in the magnetic core.

8. The coil-encased magnetic core according to claim 5, characterized in that, The small diameter powder has a D90 of less than 4μm and is coated with an insulating coating.

9. The coil-encased magnetic core according to claim 5, characterized in that, The small-diameter powder is composed of a Ni-Fe alloy.

10. The coil-encased magnetic core according to claim 5, characterized in that, The proportion of the small-diameter powder in the total magnetic powder is 6.5-20%.

11. The coil-encased magnetic core according to claim 5, characterized in that, The insulating coating of the large-diameter powder of the magnetic powder is thicker than the insulating coating of the small-diameter powder of the magnetic powder.

12. The coil-encased magnetic core according to claim 5, characterized in that, It also contains medium-diameter powder with a particle size larger than the small-diameter powder and a particle size smaller than the large-diameter powder.

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