JP7018710B2 - Electronic components, manufacturing methods of electronic components and electronic modules - Google Patents

Description

The present invention relates to an electronic component, a method for manufacturing the electronic component, and an electronic component module, and more particularly to an electronic component represented by a ferrite bead inductor or the like.

Switching power supplies are used in recent electronic devices, and radiation noise from AC (Alternating Current) cables has become a problem. Electronic components such as ferrite bead inductors are used to reduce this radiation noise.

In general, it is known that the frequency characteristic of inductance in electronic components such as ferrite bead inductors has a frequency region in which a peak suddenly appears immediately before the self-resonant frequency. Therefore, normally, a region having a relatively small inductance fluctuation of the frequency before the frequency region showing this peak is used. The boundary between this frequency domain and the frequency domain indicating the peak may be referred to as the frequency usage limit. The frequency usage limit is not uniquely defined, but can be shown as a frequency in which the inductance value is increased by a certain percentage from the nominal value, for example, a frequency in which the inductance value is increased by 10% from the nominal value. .. In addition, there is a frequency that shows a peak in the impedance frequency characteristics. The frequency indicating this peak can be used as a guide for how far the frequency can be used. In general, electronic components such as ferrite bead inductors have a high frequency usage limit, and those having high impedance in a wider frequency band are desired. However, in electronic components such as ferrite bead inductors, the frequency usage limit and the frequency characteristics of impedance greatly change due to fluctuations in the DC current value, so that the usable frequency band is limited.

Further, in electronic components such as ferrite bead inductors, the magnetic permeability of the magnetic material becomes saturated as the applied DC current value increases. As a result, there is a problem that the inductance value of an electronic component such as a ferrite bead inductor is lowered and the effect of reducing radiation noise is reduced.

Generally, the relationship between the flowing current value and the inductance value is called a DC superimposition characteristic. Good DC superimposition characteristics mean that (1) the inductance value obtained is large with respect to the DC current value flowing through the coil, and (2) the inductance value does not change even if the DC current value flowing through the coil fluctuates. It means that two characteristics are good. If the DC superimposition characteristic is poor, problems such as unnecessary resonance of the circuit and self-oscillation also occur.

In order to improve the latter DC superimposition characteristic, that is, the change in the inductance value due to the fluctuation of the DC current value flowing through the coil, a magnetic material having a small magnetic permeability may be used for the core. However, the former DC superimposition characteristic, that is, the inductance value obtained with respect to the DC current value flowing through the coil becomes small, and the noise reduction effect also becomes small. In this way, electronic components such as ferrite bead inductors are required to have a good balance of the antinomy characteristics of "larger inductance value when DC current is applied" and "smaller change in inductance value when DC current is applied". There is.

As another method for improving the DC superimposition characteristic, an electronic component that alleviates magnetic saturation by blocking the magnetic flux circulating along the inner and outer surfaces of the coil with a magnetic gap has been proposed. For example, the electronic component proposed in Patent Document 1 (Japanese Patent Laid-Open No. 10-199730) has a void structure in the core as a magnetic gap. However, there are manufacturing difficulties such as powder molding and member assembly. For this reason, it has been difficult to provide a void structure in the core of an electronic component manufactured by continuous molding as in Patent Document 2 (Japanese Patent Laid-Open No. 8-83730). FIG. 11 is an explanatory diagram showing the magnetic flux of the electronic component of the prior art proposed in Patent Document 2. The one-point chain frame in FIG. 11 is a schematic enlarged view near the boundary between the magnetic material and the coil. The electronic component shown in FIG. 11 includes a magnetic material portion, a coil, and an external electrode. The magnetic material portion is composed of a magnetic material made of a magnetic material having a high magnetic permeability as a shaft core and a magnetic material made of a magnetic material having a high magnetic permeability as an outer cover. In the electronic component of the prior art shown in FIG. 11, since the circumference of the coil is entirely covered with a magnetic material having a high magnetic permeability, the magnetic flux is concentrated on the magnetic material in the vicinity of the coil. Therefore, magnetic saturation is likely to occur, and the DC superimposition characteristic is poor. Further, as shown in the one-point chain frame of FIG. 11, leakage flux is generated between the coil pitches and inhibits the magnetic flux generated by the coils, so that the inductance value decreases.

Therefore, using the laminating method, in Patent Document 3 (Japanese Patent Laid-Open No. 5-413823) and Patent Document 4 (Japanese Patent Laid-Open No. 9-330819), instead of the void structure, a part of the core is made of a low magnetic permeability material containing an insulating material. A laminated electronic component having a magnetic gap has been proposed.

Japanese Unexamined Patent Publication No. 10-199730 Japanese Unexamined Patent Publication No. 8-83730 Japanese Unexamined Patent Publication No. 5-41323 Japanese Unexamined Patent Publication No. 9-330819

However, in the electronic components proposed in Patent Documents 3 and 4, the circumference of the internal conductor is entirely covered with a magnetic material having a low magnetic permeability, so that the effective magnetic permeability of the magnetic material constituting the internal conductor is low. .. For this reason, the inductance value when a direct current current is applied cannot be sufficiently obtained, and the direct current superimposition characteristics are not compatible with each other in a well-balanced manner. Further, the laminated electronic component requires a complicated manufacturing process, and it is difficult to easily perform continuous molding as in the extrusion molding proposed in Patent Document 2. Furthermore, no consideration was given to changes in the frequency usage limit and impedance frequency characteristics due to fluctuations in the DC current value.

An object of the present invention is to provide an electronic component which has a good frequency band and DC superimposition characteristics and can be easily continuously molded.

The electronic component of the present invention includes an insulator portion made of a plurality of ceramic insulator materials having different magnetic permeability, a coil having a central axis embedded in the insulator portion, and a central axis direction in which the central axis extends. It is provided with an external electrode formed on the surface of the insulator portion and directly bonded to the coil, and the insulator portion includes at least the central axis and is located inside the inner peripheral surface of the coil. A first insulator made of a ceramic insulator material having a magnetic coefficient, a third insulator made of a ceramic insulator material having a high magnetic permeability located outside the inner peripheral surface of the coil, and the first and third insulators. A second insulator, which is sandwiched between the insulators and is made of a low magnetic permeability ceramic insulator material, is characterized in that the second insulator is in contact with at least a part of the coil. do.

According to the present invention, it is possible to suppress changes in the frequency usage limit and the frequency characteristics of the impedance due to fluctuations in the DC current value, and thereby without being limited by fluctuations in the usable frequency due to fluctuations in the DC current value. A good frequency band can be obtained. In addition, it is possible to achieve both the two DC superimposition characteristics of "larger inductance value when DC current is applied" and "smaller change in inductance value when DC current is applied" in a well-balanced manner. Further, since the coil and the external electrode provided in the direction of the central axis extending in the central axis of the coil are directly bonded, continuous molding can be easily performed.

It is a schematic diagram which shows the 1st structure of the electronic component which concerns on 1st Embodiment. It is explanatory drawing which shows the magnetic flux of the electronic component which concerns on 1st Embodiment. It is a schematic sectional drawing which shows the 2nd structure of the electronic component which concerns on 1st Embodiment. It is a schematic cross-sectional view which shows the 2nd structure of the electronic component which concerns on 1st Embodiment which used ferrite as an insulator material. It is a schematic cross-sectional view which shows the structure of the electronic component which concerns on 2nd Embodiment. It is a schematic cross-sectional view which shows the structure of the electronic component which concerns on other embodiment. It is a schematic diagram of the manufacturing method of the electronic component which concerns on 1st Embodiment. It is a schematic diagram of the manufacturing method of the electronic component which concerns on 2nd Embodiment. It is a graph which shows the frequency characteristic of the inductance in an example of the prior art and the electronic component of this invention. It is a graph which shows the frequency characteristic of the impedance in an example of the prior art and the electronic component of this invention. It is explanatory drawing which shows the magnetic flux of the electronic component of the prior art.

The present invention will be described in detail below with reference to the drawings as appropriate. These are non-limiting examples, and the present invention is not limited to the illustrated embodiments. In addition, since the characteristic parts of the invention may be emphasized in the drawings, the accuracy of the scale is not always guaranteed in each part of the drawings.

<First configuration of electronic components according to the first embodiment>
FIG. 1 is a schematic diagram showing a first configuration of an electronic component according to a first embodiment. FIG. 1A is a schematic perspective view showing a first configuration of an electronic component according to a first embodiment. 1 (B) is a schematic cross-sectional view taken along the line AA'(the central axis of the coil) of FIG. 1 (A). FIG. 1C is a schematic cross-sectional view taken along the line BB'of FIG. 1B. In the following description, an inductor is mentioned as one of the specific embodiments of the electronic component which is the object of the present invention, but the electronic component may be, for example, a transformer, a common mode filter for a power supply, or the like. An electronic module including such an electronic component is also an embodiment of the present invention.

As shown in FIG. 1A, the electronic component of the present invention has an insulator portion 10 (for example, L: 1.0 to 10.0 mm, W: 0.5 to 10.0 mm, H: 0.5 to 10.0 mm), a coil 20 (for example, a wire diameter of 25 to 200 μm) and an external electrode 30 (for example, e: 0 to 4.0 mm).

The insulator portion 10 is composed of a first insulator 10a, a second insulator 10b, and a third insulator 10c. In the first configuration of the electronic component according to the first embodiment, the first insulator 10a includes the central axis AA'of the coil 20 and is located inside the inner peripheral surface of the coil 20. The second insulator 10b is located sandwiched between the first insulator 10a and the third insulator 10c. The third insulator 10c is located outside the inner peripheral surface of the coil 20. Here, "inside" means a direction approaching the central axis AA'of the coil 20 in the electronic component, and "outside" means a direction toward the outer surface of the electronic component. With this configuration, the inner peripheral surface of the coil 20 is covered with the second insulator 10b. That is, the second insulator 10b is in contact with at least a part of the coil 20. In the direction orthogonal to the central axis direction of the coil 20, the average thickness, which is the average value of the thickness t of the second insulator 10b, is, for example, 30 to 300 μm. Here, the average thickness means the average value of the thickness t measured 20 times or more in the direction orthogonal to the central axis direction of the coil 20. The average thickness of the second insulator 10b is preferably 50 μm or more, and more preferably 100 μm to 200 μm.

The ceramic insulator material constituting the insulator portion 10 is not limited depending on the required magnetic permeability and frequency characteristics such as Ni-Zn-Cu ferrite, Mn-Zn-Cu ferrite, or a metallic magnetic material. Illustrated. In the present invention, the magnetic characteristics of the insulator will be described by the magnetic permeability, but it can also be specified by the saturation magnetic flux density.

The first insulator 10a and the third insulator 10c constituting the insulator portion 10 of the electronic component are made of a ceramic insulator material having a high magnetic permeability, and have a magnetic permeability of 50 or more. The second insulator 10b is made of a ceramic insulator material having a low magnetic permeability, and has a magnetic permeability of 30 or less. Preferably, the magnetic permeability of the first insulator 10a is 100 to 1500, the magnetic permeability of the second insulator 10b is 3 to 30, and the magnetic permeability of the third insulator 10c is 50 to 1500. be. If the magnetic permeability of the second insulator 10b is smaller than 3, it becomes difficult to fire the first insulator 10a and the third insulator 10c at the same time, which is not preferable. If the magnetic permeability of the second insulator 10b is larger than 30, the magnetic flux concentrated on the insulator near the coil 20 cannot be dispersed in a well-balanced manner, which is not preferable.

The coil 20 is formed by forming a conducting wire, which is a conductive material, into a spiral shape. The spiral shape has a central axis, and the central axis is shown by the alternate long and short dash line AA'in FIG. 1 (A). Although it is wound in a spiral shape in the present embodiment, it can take various shapes depending on the specifications such as a spiral shape, and is not limited to the present embodiment. As the conductive material, various materials used as electrodes of conventional electronic parts can be used without particular limitation, typically Ag, and preferably Ag substantially free of other metals. , 100 parts by weight of Ag and 50 parts by weight or less of other metals may be mixed or alloyed, and examples of the other metals include, but are not limited to, Au, Cu, Pt, Pd and the like.

The external electrodes 30 are provided on both end faces of the insulator portion 10 (longitudinal direction of the insulator) in the central axis direction in which the central axis AA'of the coil 20 extends, and also cover the periphery of both end faces thereof. It may be provided. As the material of the external electrode 30, various materials used as the external electrode 30 of the conventional electronic component can be used without particular limitation, and for example, Ag, Cu, Pt, Ni, Zn, Sn and the like are not limited. Illustrated.

Here, both ends of the coil 20 joined to the external electrode 30 do not require a leader wire provided in the laminated electronic component. In a laminated electronic component, it is difficult to bend a conductor wire from a lead-out portion to a connection to a terminal electrode because the conductor wire is directional, and a large space is required. In the electronic component of this embodiment, the external electrode 30 and the spiral coil 20 are directly bonded. Therefore, the electronic component of the present embodiment can increase the number of turns of the coil 20 while reducing the size as compared with the laminated electronic component provided with the leader wire, and obtains a high inductance value with a simple configuration. be able to. Further, the labor of processing is saved, and continuous molding becomes easy.

FIG. 2 is an explanatory diagram showing the magnetic flux of the electronic component according to the first embodiment. The electronic component shown in FIG. 2 is a second insulator made of a ceramic insulator material having a low magnetic permeability between a first insulator 10a made of a ceramic insulator material having a high magnetic permeability and a third insulator 10c. It has a body 10b. The second insulator 10b arranged so as to block the magnetic flux D circulating along the inner and outer surfaces of the coil 20 can adjust the amount of the magnetic flux D flowing with respect to the coil 20 in a well-balanced manner, and the insulator in the vicinity of the coil 20 can be adjusted. The concentration of the magnetic flux D can be dispersed. Further, as shown in the one-point chain frame of FIG. 2, the leakage flux E generated between the pitches of the coils 20 is reduced, and the decrease in the inductance value due to the inhibition of the magnetic flux is suppressed. Therefore, it is possible to suppress changes in the frequency usage limit and impedance frequency characteristics due to fluctuations in DC current, and "larger inductance value when DC current is applied" and "smaller changes in inductance value when DC current is applied". It is possible to achieve both of the two DC superimposition characteristics in a well-balanced manner. The second insulator 10b may be preferably 3% or less, more preferably 1% or less, with respect to the larger magnetic permeability of the first insulator 10a and the third insulator 10c. If it is better.

<Second configuration of electronic components according to the first embodiment>
3A and 3B are schematic cross-sectional views showing a second configuration of the electronic component according to the first embodiment. The second configuration of the electronic component according to the first embodiment is a preferable example of the first configuration of the electronic component according to the first embodiment.

In the second configuration of the electronic component according to the first embodiment, the first insulator 10a includes the central axis AA'of the coil 20 and is located inside the inner peripheral surface of the coil 20. The second insulator 10b is located sandwiched between the first insulator 10a and the third insulator 10c. The third insulator 10c is located outside the inner peripheral surface of the coil 20 and inside the outer peripheral surface of the coil 20. With this configuration, the inner peripheral surface of the coil 20 is covered with the second insulator 10b, and at least a part of the coil 20 is located in the second insulator 10b. Preferably, at least 10% or more of the wire diameter of the coil 20 is located in the second insulator 10b in the direction orthogonal to the central axis direction of the coil 20.

4 (A) and 4 (B) show the first embodiment in the case where the first, second and third insulators 10a, 10b and 10c using ferrite as the ceramic insulator material are integrally formed by firing. It is a schematic cross-sectional view which shows the 2nd structure of the electronic component which concerns on. The one-point chain frame of FIGS. 4A and 4B is a schematic enlarged view of the vicinity of the boundary between the first, second and third insulators 10a, 10b and 10c and the coil 20.

As shown in FIGS. 4A and 4B, diffusion regions 12a and 12b in which the materials of the respective insulators are mixed are formed on the boundary surface with the first, second and third insulators 10a, 10b and 10c. It is formed. The presence of the diffusion regions 12a and 12b can be clearly determined, for example, in an SEM (Scanning Electron Microscope) observation image or the like. When the first, second and third insulators 10a, 10b and 10c using ferrite as the ceramic insulator material are integrally formed by firing, as shown in FIG. 4A, the coil 20 has a diffusion region. It is located within 12b. Therefore, the volume of the diffusion region 12b occupied in the insulator portion 10 becomes smaller in volume of the coil 20 located in the diffusion region 12b, and it is preferable in that the magnetic permeability of the required portion in the vicinity of the coil 20 can be secured. be. Further, as shown in FIG. 4A, when the second insulator 10b including the diffusion region 12b is not completely divided by the coil 20 and is continuous, the average thickness of the second insulator 10b is calculated. It is suitable in that it does not cause a defect even if it is made small. Further, as shown in FIG. 4B, when there is continuity between the second insulator 10b and the diffusion region 12b, the adhesion between the second insulator 10b and the third insulator 10c is good, and the adhesion is good. It is preferable in that the connection between the second insulator 10b and the third insulator 10c is ensured, and the electronic component can cope with a moisture-resistant environment.

<Electronic components according to the second embodiment>
FIG. 5A is a schematic cross-sectional view showing the configuration of the electronic component according to the second embodiment. 5 (B) is a schematic cross-sectional view taken along the line CC'of FIG. 5 (A). The difference from the configuration of the electronic component according to the first embodiment is the position where the coil 20 and the second insulator 10b are in contact with each other. In the first embodiment, the inner peripheral surface of the coil 20 is covered with the second insulator 10b, but in the second embodiment, the outer peripheral surface of the coil 20 is covered with the second insulator 10b.

In the electronic component according to the second embodiment, the first insulator 10a includes the central axis AA'of the coil 20 and is located inside the inner peripheral surface of the coil 20, and the second insulator 10b is It is located sandwiched between the first insulator 10a and the third insulator 10c, and the third insulator 10c is located outside the outer peripheral surface of the coil 20. The average thickness of the second insulator 10b in the direction orthogonal to the central axis direction of the coil 20 is, for example, the wire diameter of the coil 20 to 300 μm. The average thickness of the second insulator 10b is preferably 100 μm or more, and more preferably 120 μm to 200 μm. The first insulator 10a and the third insulator 10c constituting the insulator portion 10 of the electronic component are made of a ceramic insulator material having a high magnetic permeability, and have a magnetic permeability of 50 or more. The second insulator 10b is made of a ceramic insulator material having a low magnetic permeability, and has a magnetic permeability of 30 or less. Preferably, the magnetic permeability of the first insulator 10a is 100 to 1500, the magnetic permeability of the second insulator 10b is 3 to 30, and the magnetic permeability of the third insulator 10c is 50 to 1500. be. If the magnetic permeability of the second insulator 10b is smaller than 3, it becomes difficult to fire the first insulator 10a and the third insulator 10c at the same time, which is not preferable. If the magnetic permeability of the second insulator 10b is larger than 30, the magnetic flux concentrated on the insulator near the coil 20 cannot be dispersed in a well-balanced manner, which is not preferable. The second insulator 10b may be preferably 3% or less, more preferably 1% or less, with respect to the larger magnetic permeability of the first insulator 10a and the third insulator 10c. If it is better.

In the electronic component according to the second embodiment, the third insulator 10c as an outer cover located on the outermost side of the insulator portion 10 is manufactured by covering the second insulator 10b. Since the third insulator 10c covers the second insulator 10b having smaller irregularities than the coil 20, a good shape can be prepared, the dimensional variation of the electronic component is small, and the shape stability is improved. Suitable.

More preferably, when the material of the insulator portion 10 is ferrite, the diffusion generated when the first, second and third insulators 10a, 10b and 10c constituting the insulator portion 10 are joined by firing. The coil 20 may be located in the regions 12a and 12b.

<Electronic components according to other embodiments>
FIG. 6 is a schematic cross-sectional view showing the configuration of electronic components according to other embodiments. 6A and 6B show an example of electronic components having different inner diameters of the coil 20 at both terminals of the coil 20. FIG. 6C shows an example of an electronic component composed of a plurality of coils 20. FIG. 6D shows an example of an electronic component in which the coil 20 is in contact with all of the first, second and third insulators 10a, 10b and 10c constituting the insulator portion 10. The configuration of the electronic component according to the present embodiment is based on the assumption that, for example, as long as the second insulator 10b made of a ceramic insulator material having a low magnetic permeability and the coil 20 are in contact with each other, they may be appropriately combined. , The scope of the present invention is not limited by the inner diameter of the coil 20 or the number of coils 20.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the embodiments described in these examples.

The electronic component of the present invention can be manufactured so as to have the above-mentioned configuration by appropriately using the prior art. The following is an example of a non-limiting manufacturing method.

<Manufacturing method of electronic components according to the first embodiment>
FIG. 7 is an explanatory diagram of a method for manufacturing an electronic component according to the first embodiment.

As shown in FIG. 7, the binder and the insulator raw material powder made of Ni—Zn—Cu ferrite having a magnetic permeability of, for example, 900 are kneaded with a kneader 51 to homogenize the insulator raw material powder and the binder. 61 is pressurized and supplied to the primary extruder 71, and a desired first insulator having a diameter of, for example, 0.2 to 2.5 mm, formed from a mouthpiece of an outlet having a circular cross section of the primary extruder 71. A rod 81 having a circular cross section of a winding core of 10a is extruded at a rate of, for example, 30 m / min and dried in a dryer 91.

Next, the rod 81 is again fed into the secondary extrusion molding machine 72. In the secondary extruder 72, a kneading material 62 obtained by kneading a binder and an insulator raw material powder made of Ni—Zn—Cu ferrite having a magnetic permeability of, for example, 5 in a kneader 52 is pressed against the secondary extruder 72. The rod body 82 having a circular cross section, in which the second insulator 10b is bonded to the rod body 81, is extruded from the base of the outlet having a circular cross section of the secondary extrusion molding machine 72.

Here, when the coil 20 is not located in the second insulator 10b as in the first configuration of the electronic component according to the first embodiment shown in FIG. 1, the rod 82 is dried by the dryer 92. After that, the lead wire 22 is wound by the winding machine 100. On the other hand, when the coil 20 is located in the second insulator 10b as in the second configuration of the electronic component according to the first embodiment shown in FIG. 3, the rod 82 is not dried. , The lead wire 22 is wound by the winding machine 100. By not incorporating the drying process by the dryer 92, the pitch of the winding machine 100 and the like can be adjusted, and the lead wire 22 can be embedded in the rod body 82 which is the winding core. Therefore, the coil 20 is located in the second insulator 10b as in the second configuration of the electronic component according to the first embodiment shown in FIG.

Next, the rod body 82 around which the conductor wire 22 is wound is fed into the tertiary extrusion molding machine 73. In the tertiary extruder 73, a kneading material 63 obtained by kneading a binder and an insulator raw material powder made of Ni—Zn—Cu ferrite having a magnetic permeability of, for example, 900 in a kneader 53 is pressed against the tertiary extruder 73. The rod body 82 is supplied and the rod body 82 is covered with the kneading material 63 to form an outer cover body 83 having a rectangular cross section.

Next, it is cut according to the size of the firing furnace or the shape of the setter laid underneath, fired at 600 to 1000 ° C., for example, 900 ° C., and cut with a cutter according to the dimensions of individual electronic components. The main body 41, which is each of the cut insulating portions 10, is barrel-polished with barrel powder and water to give rounded corners. Then, a silver paste composed of silver powder and a solvent is applied to both end faces of the main body 41 and the end portions of the outer peripheral surface connected to the silver paste and baked to form the external electrode 30. At this time, the terminals of the coil 20 exposed on both end faces of the main body 41 and the external electrodes 30 are connected. The silver layer of the external electrode 30 is nickel-plated and solder-plated.

<Manufacturing method of electronic components according to the second embodiment>
FIG. 8 is an explanatory diagram of a method for manufacturing an electronic component in the second embodiment.

As shown in FIG. 8, the binder and the insulator raw material powder made of Ni—Zn—Cu ferrite having a magnetic permeability of, for example, 900 are kneaded with a kneader 51 to homogenize the insulator raw material powder and the binder. 64 is pressurized and supplied to the primary extruder 71, and a desired first insulator having a diameter of, for example, 0.2 to 2.5 mm, formed from a mouthpiece of an outlet having a circular cross section of the primary extruder 71. The rod 84 having a circular cross section of the winding core of 10a is extruded at a rate of, for example, 30 m / min and dried in a dryer 91. After drying, the conductor wire 22 is wound around the rod body 84 by the winding machine 100.

Next, the rod body 84 around which the conductor wire 22 is wound is fed into the secondary extrusion molding machine 72. In the secondary extruder 72, a kneading material 65 obtained by kneading a binder and an insulator raw material powder made of Ni—Zn—Cu ferrite having a magnetic permeability of, for example, 5 in a kneader 52 is pressed against the secondary extruder 72. The rod 85 having the second insulator 10b bonded to the rod 84 is extruded from the mouthpiece of the outlet having a circular cross section of the secondary extrusion molding machine 72, and dried by the dryer 92.

Then, the rod 85 is fed into the tertiary extrusion molding machine 73 again. In the tertiary extruder 73, a kneading material 66 obtained by kneading a binder and an insulator raw material powder made of Ni—Zn—Cu ferrite having a magnetic permeability of, for example, 900 in a kneader 53 is pressed against the tertiary extruder 73. The rod body 85 is supplied and the rod body 85 is covered with the kneading material 66, and the outer body body 86 having a square cross section is formed. Since the steps after forming the outer cover 86 are the same as the method for manufacturing electronic components according to the first embodiment described above, the description thereof will be omitted.

The electronic component of the present invention was actually produced by the above-mentioned manufacturing method, and the average thickness of the second insulator 10b was changed. It was measured whether it changed.

The dimensions of the insulator portion 10 of the electronic component were 4.5 mm × 3.2 mm × 3.2 mm. The magnetic permeability of the first insulator 10a was 900, the magnetic permeability of the second insulator 10b was 3, and the magnetic permeability of the third insulator 10c was 900. The average thickness of the second insulator 10b was calculated from the average value measured at 20 points by polishing the cross section passing through the coil axis along the coil axis. The wire diameter of the coil 20 was 100 μm, and the pitch of the coil 20 was 240 μm. 9 and 10 show the measurement results of the frequency characteristics of the inductance and the frequency characteristics of the impedance in the electronic component of the first configuration according to the conventional and the first embodiment of the present invention, respectively.

FIG. 9 is a graph showing the frequency characteristics of the inductance in the electronic component of the first configuration according to the conventional and the first embodiment of the present invention. The vertical axis of FIG. 9 shows the inductance (μH), and the horizontal axis shows the frequency (MHz). 9 (A) shows the conventional electronic component shown in FIG. 11, that is, an electronic component not provided with the second insulator 10b, and FIG. 9 (B) shows the present invention in which the average thickness of the second insulator 10b is 50 μm. An example of an electronic component, FIG. 9C, is an example of an electronic component of the present invention in which the average thickness of the second insulator 10b is 100 μm. As shown in FIG. 9, the electronic component of the example of the present invention has a smaller change in the inductance value even when the current value is changed, as compared with the conventional electronic component. Further, the frequency usage limit is high and the inductance value is high. Therefore, in the electronic component of the present invention, a good frequency band can be obtained without being limited by the fluctuation of the usable frequency due to the fluctuation of the DC current value. Further, the electronic component of the present invention has a well-balanced balance between the two DC superimposition characteristics of "larger inductance value when DC current is applied" and "smaller change in inductance value when DC current is applied". Further, as the average thickness of the second insulator 10b of the electronic component of the present invention increases, the frequency usage limit becomes higher, and the change in the inductance value becomes smaller even when the current value is changed.

FIG. 10 is a graph showing the frequency characteristics of impedance in the electronic component of the first configuration according to the conventional and the first embodiment of the present invention. The vertical axis of FIG. 10 shows impedance (Ω), and the horizontal axis shows frequency (MHz). The conventional electronic component shown in FIG. 11, that is, the electronic component not provided with the second insulator 10b, and FIG. 10B is an example electronic component of the present invention in which the average thickness of the second insulator 10b is 50 μm. FIG. 10C is an electronic component of an example of the present invention in which the average thickness of the second insulator 10b is 100 μm. As shown in FIG. 10, the electronic component of the example of the present invention has a smaller change in the peak point of impedance even when the current value is changed, as compared with the conventional electronic component. Therefore, in the electronic component of the present invention, a good frequency band can be obtained without being limited by the fluctuation of the usable frequency due to the fluctuation of the DC current value. Further, as the average thickness of the second insulator 10b of the electronic component of the present invention becomes larger, the change in impedance becomes smaller even when the current value is fluctuated, and the peak point of the impedance shifts to the higher frequency side.

The following measurements were made for the electronic components of Examples and Comparative Examples below. The dimensions of the insulator portion 10 of the electronic component were 4.5 mm × 3.2 mm × 3.2 mm. The magnetic permeability of the first insulator 10a was 900, the magnetic permeability of the second insulator 10b was 3, and the magnetic permeability of the third insulator 10c was 900. The average thickness of the second insulator was calculated from the average value measured at 20 points by polishing the cross section passing through the coil axis along the coil axis. The wire diameter of the coil 20 was 100 μm, and the pitch of the coil 20 was 240 μm. The position (%) of the coil in the fifth embodiment is the thickness (μm) of the coil 20 located in the second insulator 10b in the direction orthogonal to the central axis direction of the coil 20 with the wire diameter of the coil 20 being 100 μm. It is the average value of the divided values (%). The thickness of the coil 20 located in the second insulator 10b was calculated by polishing the cross section passing through the coil shaft along the coil shaft and measuring it using an optical microscope. For the measurement, an LCR meter was used, and 10 pieces were measured for each Example and Comparative Example to obtain an average value. The inductance in Table 1 is a DC current of 200 mA and an inductance value at a frequency of 10 MHz. The frequency usage limit in Table 1 has no unambiguous definition, but here it is a frequency in which the inductance value is increased by 10% from the nominal value. The impedance max frequency (MHz) in Table 1 is a frequency at which the impedance at a direct current of 200 mA becomes the maximum value (peak value).

Table 2 shows the inductance values at a frequency of 10 MHz at each DC current value (200, 400, 600 and 800 mA). In the comparative example, the inductance value fluctuates greatly depending on the direct current, whereas in the embodiment, the larger the average thickness of the second insulator 10b, the more the inductance value does not fluctuate even if the direct current value changes. This indicates that it can always be used as a stable inductance regardless of the value of the DC current value.

Table 3 shows the impedance max frequency (MHz), which is the frequency at which the impedance at each DC current value (200, 400, 600 and 800 mA) becomes the maximum value (peak value). The comparative example greatly fluctuates due to the direct current current, and when the direct current value is low, the impedance max frequency is lower than when the direct current value is high, whereas in the embodiment, the average of the second insulator 10b. The larger the thickness, the larger the impedance max frequency does not fluctuate even if the DC current value changes, and further, the impedance max frequency is high both when the DC current value is low and when the DC current value is high. This indicates that it can always be used stably up to a high frequency regardless of the value of the DC current value.

10 Insulator part 10a First insulator 10b Second insulator 10c Third insulator 20 Coil 30 External electrode

Claims (7)

An insulator part made of multiple ceramic insulator materials with different magnetic permeability,
A coil having a central axis embedded in the insulator portion and
An electronic component comprising an external electrode formed on the surface of the insulator portion in the central axis direction in which the central axis extends and directly bonded to the coil.
The insulator part is at least
A first insulator made of a ceramic insulator material having a high magnetic permeability, which includes the central axis and is located inside the inner peripheral surface of the coil.
A third insulator made of a ceramic insulator material having a high magnetic permeability, which is located outside the inner peripheral surface of the coil,
A second insulator that covers the first insulator and is sandwiched between the first and third insulators and is made of a ceramic insulator material having a low magnetic permeability.
The average thickness of the second insulator is 100 μm or more in the direction orthogonal to the central axis direction.
The magnetic permeability of the second insulator is 3 to 30, and the magnetic permeability is 3 to 30.
The magnetic permeability of the second insulator is 3% or less of the magnetic permeability of the larger magnetic permeability of the first and third insulators.
At least a portion of the coil is located within the second insulator.
The third insulator is located outside the inner peripheral surface of the coil and inside the outer peripheral surface of the coil.
Electronic components. The electronic component according to claim 1, wherein at least 10% or more of the wire diameter of the coil is located in the second insulating body in a direction orthogonal to the central axis direction. An insulator part made of multiple ceramic insulator materials with different magnetic permeability,
A coil having a central axis embedded in the insulator portion and
An electronic component comprising an external electrode formed on the surface of the insulator portion in the central axis direction in which the central axis extends and directly bonded to the coil.
The insulator part is at least
A first insulator made of a ceramic insulator material having a high magnetic permeability, which includes the central axis and is located inside the inner peripheral surface of the coil.
A third insulator made of a ceramic insulator material having a high magnetic permeability, which is located outside the inner peripheral surface of the coil,
A second insulator that covers the first insulator and is sandwiched between the first and third insulators and is made of a ceramic insulator material having a low magnetic permeability.
The average thickness of the second insulator is 100 μm or more in the direction orthogonal to the central axis direction.
The magnetic permeability of the second insulator is 3 to 30, and the magnetic permeability is 3 to 30.
The magnetic permeability of the second insulator is 3% or less of the magnetic permeability of the larger magnetic permeability of the first and third insulators.
The coil is located in the second insulator and
The third insulator is located outside the outer peripheral surface of the coil.
Electronic components. The electronic component according to any one of claims 1 to 3 , wherein the average thickness of the second insulator is 100 μm to 300 μm in a direction orthogonal to the central axis direction. One of claims 1 to 4 , wherein the magnetic permeability of the second insulator is 1 % or less of the magnetic permeability of the larger magnetic permeability of the first and third insulators. Electronic components described in the section. An electronic module including the electronic component according to any one of claims 1 to 5 . The process of forming a winding core by extruding a kneaded material, which is a mixture of insulator raw material powder and binder, and
The process of winding a conducting wire around the core to form a coil,
The step of forming the outer cover by extruding the kneaded material and
A step of firing the core and the outer body and then cutting them to a predetermined length.
The method for manufacturing an electronic component according to any one of claims 1 to 6 , further comprising a step of forming an external electrode to be joined to the coil.

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