JP7302348B2 - inductors and electronic circuits - Google Patents

Description

The present disclosure relates to inductors and electronic circuits comprising such inductors.

Conventionally, metal composite inductors have been used as inductors for switching power supply circuits that require small size and large current. Metal composite inductors can be used as noise countermeasures because they can reduce the gap between magnetic materials and have less magnetic flux leakage than ferrite inductors. A method of reducing noise leaking from an inductor using a shield member has also been proposed. For example, the inductor disclosed in Patent Document 1 intends to reduce noise leaking from the inductor by surrounding a core made of a metallic magnetic material that covers windings with a shield member.

JP 2018-98270 A

However, due to the parasitic capacitance of the metal magnetic material, metal composite inductors may leak noise in frequency bands higher than the low frequency band (0 to 2 MHz, etc.), and there is a problem that noise in these frequency bands cannot be sufficiently reduced. there were.

Further, in the inductor disclosed in Patent Document 1, by adjusting the thickness of the shield member, it is possible to shield from low frequencies to high frequencies, but it is necessary to newly add a terminal for connecting the shield member to the substrate. There was a problem that the structure became complicated.

The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide an inductor and an electronic circuit capable of reducing noise leakage from low to high frequencies with a simple structure.

To achieve the above object, an inductor (30) according to an embodiment of the present disclosure includes a coil (300), a metal magnetic member (310) formed so as to cover the coil with a soft magnetic metal, and a ferrite magnetic A ferrite magnetic member ( 323 ) made of a material through which at least one of the coil input side end (301) and the coil output side end (302) passes , and on the opposite side of the metal magnetic member from the substrate side A non-grounded metal plate (340) placed in contact with the metal magnetic member and between the metal magnetic member and the ferrite magnetic member, and between the metal magnetic member and the ferrite magnetic member on the substrate side of the metal magnetic member a non-grounded metal plate (341) placed in the

In this configuration, since the input-side end wire and the output-side end wire of the coil pass through the ferrite magnetic member, when current flows through the end wire, the ferrite magnetic member around the end wire causes Magnetic loss occurs around the end wire. The magnetic loss reduces the high frequency band and the intermediate frequency band of the current generating the magnetic field, thereby reducing the noise in the high frequency band and the intermediate frequency band caused by the current. As a result, it is possible to reduce the noise in the high frequency band and the intermediate frequency band leaking from the inductor.

1 is a schematic diagram of an electronic circuit according to a first embodiment of the present disclosure; FIG. 1 is a perspective view of an inductor according to a first embodiment; FIG. FIG. 3 is a vertical sectional view showing the AA section of the inductor shown in FIG. 2; FIG. 4 is a diagram showing the level of noise leaked from an inductor; FIG. 5 is a perspective view of an inductor according to a second embodiment; FIG. 6 is a vertical sectional view showing a BB section of the inductor shown in FIG. 5; FIG. 11 is a perspective view of an inductor according to a third embodiment; FIG. 8 is a vertical sectional view showing a CC section of the inductor shown in FIG. 7; FIG. 11 is a perspective view of an inductor according to a fourth embodiment; FIG. 10 is a vertical sectional view showing a DD section of the inductor shown in FIG. 9; FIG. 11 is a perspective view of an inductor according to a fifth embodiment; FIG. 12 is a vertical sectional view showing the EE section of the inductor shown in FIG. 11; FIG. 11 is a perspective view of an inductor according to a sixth embodiment; FIG. 14 is a vertical sectional view showing the FF section of the inductor shown in FIG. 13; FIG. 11 is a perspective view of an inductor according to a seventh embodiment; FIG. 16 is a vertical sectional view showing the GG section of the inductor shown in FIG. 15;

<First embodiment>
A first embodiment of the present disclosure will be described below with reference to FIGS. 1 to 4. FIG. As shown in FIG. 1, the electronic circuit 1 according to the first embodiment includes a substrate 10, a power supply IC 20, an inductor 30, and a capacitor 40. As shown in FIG. A power supply IC 20 , an inductor 30 and a capacitor 40 are arranged on the substrate 10 . The inductor 30 is electrically connected to the power supply IC 20 on the input side and electrically connected to the capacitor 40 on the output side.

The power supply IC 20 is an electronic device that supplies power to the inductor 30 . The power supply IC 20 can function as a switching power supply that supplies currents of various frequencies.

The inductor 30 is an electronic element that stores and discharges electricity using interconversion of electrical energy and magnetic field energy. The inductor 30 can store power supplied by the power supply IC 20 and supply the stored power to the capacitor 40 .

The capacitor 40 is an electronic element that stores and discharges electricity. Capacitor 40 smoothes the power supplied by inductor 30 .

Next, the structure of the inductor 30 will be described with reference to FIGS. 2 and 3. FIG. The inductor 30 includes a coil 300 , a metal magnetic member 310 and a ferrite magnetic member 320 .

The coil 300 is a wound conductive wire and generates a magnetic field when energized. An input-side end portion 301 of the coil 300 is connected to an input-side external terminal 330 via a ferrite magnetic member 320 . An output-side end 302 of the coil 300 is connected to an output-side external terminal 331 .

Metal magnetic member 310 is a member formed to cover coil 300 . The metal magnetic member 310 can be formed by integrally molding a mixture of a plurality of soft magnetic metals having a small particle size such as particles or powders and a binder that holds the soft magnetic metals. In this embodiment, iron or the like can be used as the soft magnetic metal. Also, a heat-resistant resin or the like can be used as a binder for holding the soft magnetic metal.

The shape of the metal magnetic member 310 can be, for example, a rectangular parallelepiped shape as shown in FIGS. Note that the metal magnetic member 310 may have various other shapes as long as it can cover the coil 300 .

The ferrite magnetic member 320 is a member arranged so as to be in contact with the metal magnetic member 310 on the input side of the coil 300 . The ferrite magnetic member 320 can be formed by integrally molding a mixture of a plurality of ferrite magnetic materials having a small particle size such as particles or powders and a binder that holds the ferrite magnetic materials. The ferrite magnetic material used for the ferrite magnetic member 320 preferably has high magnetic permeability. In this embodiment, a heat-resistant resin or the like can be used as the binder that holds the ferrite magnetic material. The shape of the ferrite magnetic member 320 can be, for example, a flat plate shape as shown in FIGS.

The input and output sides of inductor 30 are connected to substrate 10 through external terminals 330 and 331, respectively. The external terminal 330 on the input side is electrically connected to the power supply IC 20 . The external terminal 331 on the output side is electrically connected to the capacitor 40 . When the inductor 30 is installed on the substrate 10 , the external terminals 330 and 331 on the input and output sides are soldered to the lands of the substrate 10 . Thereby, the inductor 30 can be fixed to the substrate 10 .

Next, measurement results of noise leaked from the inductor 30 according to the present embodiment will be described with reference to FIG. The graph shown in FIG. 4 shows measurement results of leakage noise when the inductor 30 with the ferrite magnetic member 320 arranged on the input side and the inductor without the ferrite magnetic member 320 arranged are driven with an alternating current of 400 kHz. showing. This graph shows both the noise propagated from the inductor 30 to the external terminal 331 on the output side and the noise spatially leaked all around the inductor 30 .

As shown in FIG. 4, in the inductor 30 in which the ferrite magnetic member 320 is arranged, the noise in the high frequency band (DAB band), the noise in the high frequency band and the low frequency band (AM Lower measured noise in the intermediate frequency band (FM band) between In the present embodiment, since the end wire on the input side of the coil 300 passes through the ferrite magnetic member 320, magnetic loss occurs around the end wire when current flows through the end wire, generating a magnetic field. The high and intermediate frequency bands of the current being generated are reduced. As a result, it is considered that the noise in the high frequency band and the intermediate frequency band caused by the current is reduced.

In this experiment, since the inductor 30 was driven with an alternating current of 400 kHz, the direction of the current flowing through the coil 300 changed periodically. Therefore, when the current direction is from the input side to the output side, it is considered that the magnetic loss due to the ferrite magnetic member 320 reduces the current in the high frequency band and the intermediate frequency band flowing from the external terminal 330 on the input side to the coil 300. I get it. On the other hand, when the current direction is from the output side to the input side, it is considered that the current in the high frequency band and the intermediate frequency band flowing from the coil 300 to the external terminal 330 on the input side decreased due to the magnetic loss caused by the ferrite magnetic member 320. . As a result, not only the noise propagated from the coil 300 to the external terminal 331 on the output side, but also the noise spatially leaking to the entire periphery of the inductor 30 is reduced.

(Effect of the first embodiment)
In the first embodiment, current passes through the input side end 301 of the coil 300 passing through the ferrite magnetic member 320 arranged between the input side external terminal 330 and the metal magnetic member 310 . Therefore, due to the magnetic loss caused by the ferrite magnetic member 320, the energy of the current in the high frequency band and the intermediate frequency band passing through the input end 301 is reduced. As a result, noise in the high frequency band and the intermediate frequency band leaking from the inductor 30 can be reduced.

Furthermore, in the first embodiment, the ferrite magnetic member 320 is formed by integrally molding a mixture of a plurality of ferrite magnetic materials and a binder that holds the ferrite magnetic materials. Therefore, the manufacturability of the ferrite magnetic member 320 can be improved. Moreover, the gap between the ferrite magnetic materials in the ferrite magnetic member 320 can be made small, and the magnetic field leaking from the inductor 30 can be reduced.

Furthermore, in the first embodiment, the metal magnetic member 310 is formed by integrally molding a mixture of a plurality of soft magnetic metals and a binder that holds the soft magnetic metals. Therefore, the manufacturability of the metal magnetic member 310 can be improved. Moreover, the gap between the soft magnetic metals in the metal magnetic member 310 can be made small, and the magnetic field leaking from the inductor 30 can be reduced. Furthermore, by reducing the gap between the soft magnetic metals in the metal magnetic member 310, it is possible to reduce the vibration noise generated by the coil 300 when energized.

Furthermore, in the first embodiment, since the entire coil 300 is covered with the metal magnetic member 310, the inductor 30 has excellent direct current current performance compared to an inductor in which only a portion of the coil is covered with the metal magnetic member. It has superposition properties. Therefore, the inductor 30 can pass a larger current than an inductor of the same size in which only part of the coil is covered with a metal magnetic member. Thereby, the inductor 30 can be miniaturized.

<Second embodiment>
Next, the second embodiment will be described with reference to FIGS. 5 and 6, focusing on differences from the first embodiment. In the second embodiment, in addition to the ferrite magnetic member 320 on the input side, a ferrite magnetic member 321 is arranged between the metal magnetic member 310 and the external terminal 331 on the output side.

As with the ferrite magnetic member 320, the ferrite magnetic member 321 is formed by integrally molding a mixture of a plurality of ferrite magnetic materials with small grain sizes such as particles or powder and a binder that holds the ferrite magnetic materials. be able to. The ferrite magnetic material and binder of the ferrite magnetic member 321 are the same as those of the ferrite magnetic member 320 . The shape of the ferrite magnetic member 321 can be a flat plate shape as shown in FIGS. An output-side end 302 of the coil 300 is connected to an output-side external terminal 331 via a ferrite magnetic member 321 .

(Effect of Second Embodiment)
In the second embodiment, a ferrite magnetic member 320 and a ferrite magnetic member 321 are arranged between a metal magnetic member 310 and an input-side external terminal 330 and an output-side external terminal 331, respectively. As a result, both the input side and the output side of the inductor 30 reduce the energy in the high frequency band and the intermediate frequency band due to the magnetic loss caused by the ferrite magnetic members 320 and 321 . As a result, the noise in the high frequency band and the intermediate frequency band leaking from the inductor 30 can be further reduced.

<Third Embodiment>
Next, the third embodiment will be described with reference to FIGS. 7 and 8, focusing on differences from the above-described embodiments. In a third embodiment, ferrite magnetic members 322 are placed on three sides of metal magnetic member 310 . These three surfaces are a substrate-side surface 311 and two opposing surfaces 312 and 313 of the four surfaces perpendicular to the substrate 10 .

As with the ferrite magnetic member 320, the ferrite magnetic member 322 is formed by integrally molding a mixture of a plurality of ferrite magnetic materials with small grain sizes such as particles or powder and a binder that holds the ferrite magnetic materials. be able to. The ferrite magnetic material and binder of the ferrite magnetic member 322 are the same as those of the ferrite magnetic member 320 . The shape of the ferrite magnetic member 322 can be U-shaped as shown in FIGS.

The external terminal 332 on the input side and the external terminal 333 on the output side are L-shaped. Bottom surfaces of these external terminals 332 and 333 are fixed to the substrate 10 . The shape of the external terminals 332 and 333 may be flat like the external terminals 330 and 331 according to the first embodiment.

An input-side end 301 of the coil 300 extends toward the substrate and is connected to an input-side external terminal 332 via a ferrite magnetic member 322 . An output-side end portion 302 of the coil 300 extends toward the substrate and is connected to an output-side external terminal 333 via a ferrite magnetic member 322 . An input-side end portion 301 and an output-side end portion 302 of the coil 300 extend parallel to the substrate 10 and connect to an input-side external terminal 332 and an output-side external terminal 333 via a ferrite magnetic member 322, respectively. may be connected.

(Effect of the third embodiment)
In a third embodiment, a non-conductive ferrite magnetic member 322 is placed between the metal magnetic member 310 and the substrate 10 . As a result, capacitive coupling between the metal magnetic member 310 and conductors in the substrate 10 can be reduced. As a result, it is possible to prevent the noise in the high frequency band and the intermediate frequency band from propagating to the substrate 10 due to the capacitive coupling.

<Fourth Embodiment>
Next, with reference to FIGS. 9 and 10, the fourth embodiment will be described, focusing on differences from the third embodiment. In the fourth embodiment, the ferrite magnetic member 323 is arranged so as to cover the entire surface of the metal magnetic member 310 . As with the ferrite magnetic member 320, the ferrite magnetic member 323 is formed by integrally molding a mixture of a plurality of ferrite magnetic materials with small grain sizes such as particles or powders and a binder that holds the ferrite magnetic materials. be able to. The ferrite magnetic material and binder of the ferrite magnetic member 323 are the same as those of the ferrite magnetic member 320 . The shape of the ferrite magnetic member 323 can be a rectangular parallelepiped shape as shown in FIGS.

(Effect of the fourth embodiment)
In a fourth embodiment, a non-conductive ferrite magnetic member 323 is also placed on top of the metal magnetic member 310 . Accordingly, when a metal component is arranged on the upper surface of the inductor 30, capacitive coupling between the metal component and the metal magnetic member 310 can be reduced. As a result, it is possible to reduce the noise in the high frequency band and the intermediate frequency band leaking upward from the inductor 30 due to the capacitive coupling.

<Fifth Embodiment>
Next, referring to FIGS. 11 and 12, the fifth embodiment will be described, focusing on differences from the third embodiment. In the fifth embodiment, a metal plate 340 is arranged so as to be in contact with the metal magnetic member 310 on the opposite side of the metal magnetic member 310 from the substrate side. Note that metal plate 340 is not grounded. Moreover, the metal plate 340 can be made into flat plate shape. Furthermore, the metal plate 340 can be made of various metals.

The external terminal 332 on the input side and the external terminal 333 on the output side are L-shaped. Bottom surfaces of these external terminals 332 and 333 are fixed to the substrate 10 . The shape of the external terminals 332 and 333 may be flat like the external terminals 330 and 331 according to the first embodiment.

(Effect of the fifth embodiment)
In the fifth embodiment, the metal plate 340 generates an eddy current in the metal plate 340 in a direction that cancels out the magnetic field generated by the coil 300 by energization. Since the metal plate 340 is not grounded, no eddy current leaks, and the eddy current generates a magnetic field opposite to the direction of the magnetic field generated by the coil 300 . As a result, the magnetic field of the coil 300 and the magnetic field of the metal plate 340 cancel each other out, so that the noise caused by the magnetic field of the coil 300 can be reduced. As a result, the magnetic field leaking from the upper portion of the inductor 30 can be reduced, and the noise caused by the leakage magnetic field can be reduced.

Moreover, in the fifth embodiment, since the metal plate 340 is not grounded, it is not necessary to provide the inductor 30 with a structure necessary for grounding the metal plate 340 . Therefore, the structure of inductor 30 can be simplified.

<Sixth Embodiment>
Next, with reference to FIGS. 13 and 14, the sixth embodiment will be described, focusing on differences from the fifth embodiment. In the sixth embodiment, in addition to metal plate 340 , metal plate 341 is arranged between metal magnetic member 310 and ferrite magnetic member 322 on the substrate side of metal magnetic member 310 . Note that metal plate 341 is not grounded. Moreover, the metal plate 341 can be made into flat plate shape. Furthermore, the metal plate 341 can be made of various metals.

An input-side end portion 301 and an output-side end portion 302 of the coil 300 extend parallel to the substrate 10 so as not to contact the metal plate 341 , respectively, and are connected via a ferrite magnetic member 322 to an input-side external terminal 332 and an output-side end portion 302 . It is connected to the external terminal 333 on the output side. The shape of the input-side external terminal 332 and the output-side external terminal 333 may be flat like the input-side external terminal 330 and the output-side external terminal 331 according to the first embodiment.

(Effect of the sixth embodiment)
In the sixth embodiment, the magnetic field generated by coil 300 causes eddy currents in metal plates 340 and 341 . Since these metal plates 340 and 341 are not grounded, no eddy current leaks, and the eddy current generates a magnetic field opposite to the direction of the magnetic field generated by the coil 300 . As a result, the magnetic field of the coil 300 and the magnetic fields of the metal plates 340 and 341 cancel each other out, so noise caused by the magnetic field of the coil 300 can be reduced. As a result, magnetic fields leaking from the upper and lower portions of the inductor 30 can be reduced, and noise caused by these leaking magnetic fields can be reduced.

<Seventh Embodiment>
Next, with reference to FIGS. 15 and 16, the seventh embodiment will be described, focusing on differences from the fourth embodiment. In the seventh embodiment, a metal plate 340 is arranged so as to be in contact with the metal magnetic member 310 on the opposite side of the metal magnetic member 310 from the substrate side. A metal plate 341 is arranged between the metal magnetic member 310 and the ferrite magnetic member 322 on the substrate side of the metal magnetic member 310 . The metal plates 340 and 341 can be flat plates. Also, the metal plates 340 and 341 can be made of various metals.

An input-side end portion 301 and an output-side end portion 302 of the coil 300 extend parallel to the substrate 10 so as not to contact the metal plate 341 , respectively, and are connected via a ferrite magnetic member 322 to an input-side external terminal 332 and an output-side end portion 302 . It is connected to the external terminal 333 on the output side. The shape of the input-side external terminal 332 and the output-side external terminal 333 may be flat like the input-side external terminal 330 and the output-side external terminal 331 according to the first embodiment.

(Effect of the seventh embodiment)
In the seventh embodiment, the magnetic field generated by coil 300 causes eddy currents in metal plates 340 and 341 . Since these metal plates 340 and 341 are not grounded, no eddy current leaks, and the eddy current generates a magnetic field opposite to the direction of the magnetic field generated by the coil 300 . As a result, the magnetic field of the coil 300 and the magnetic fields of the metal plates 340 and 341 cancel each other out, so noise caused by the magnetic field of the coil 300 can be reduced. As a result, magnetic fields leaking from the upper and lower portions of the inductor 30 can be reduced, and noise caused by these leaking magnetic fields can be reduced.

<Other embodiments>
The present disclosure is not limited to the embodiments described above, and can be implemented with various modifications. For example, in the first embodiment, a ferrite magnetic member may be arranged on the output side of the coil 300 instead of on the input side of the coil 300 . In this case, as shown in FIG. 6, the output-side end 302 of the coil 300 is connected to the output-side external terminal 331 via the output-side ferrite magnetic member 321 . As a result, on the output side of the inductor 30, the energy of the current in the high frequency band and the intermediate frequency band passing through the ferrite magnetic member 320 is reduced due to the magnetic loss caused by the ferrite magnetic member 320. FIG. As a result, noise in the high frequency band and the intermediate frequency band leaking from the inductor 30 can be reduced.

Further, in the third embodiment, the ferrite magnetic member 322 may be arranged on the surface 314 on the side opposite to the substrate side instead of the surface 311 on the substrate side. Accordingly, when a metal component is arranged on the upper surface of the inductor 30, capacitive coupling between the metal component and the metal magnetic member 310 can be reduced. As a result, it is possible to reduce the noise in the high frequency band and the intermediate frequency band leaking upward from the inductor 30 due to the capacitive coupling. In this case, the input-side end portion 301 and the output-side end portion 302 of the coil 300 extend in parallel with the substrate 10 , and are connected via the ferrite magnetic member 322 to an input-side external terminal 332 and an output-side external terminal 332 . It is connected to terminal 333 .

Furthermore, in the third embodiment, in addition to the surface 311 on the substrate side and the two surfaces 312 and 313, the ferrite magnetic member 322 may be arranged on the surface 314 opposite to the substrate side. Accordingly, when a metal component is arranged on the upper surface of the inductor 30, capacitive coupling between the metal component and the metal magnetic member 310 can be reduced. As a result, it is possible to reduce the noise in the high frequency band and the intermediate frequency band leaking upward from the inductor 30 due to capacitive coupling.

Furthermore, in the sixth and seventh embodiments, the metal plate 340 may not be placed, and only the metal plate 341 on the substrate side may be placed. Furthermore, in the sixth embodiment, in addition to the metal plates 340 and 341 , metal plates may be arranged on the four surfaces of the metal magnetic member 310 perpendicular to the substrate 10 . In this case, these metal plates should not come into contact with the input end 301 and the output end 302 of the coil 300 .

Reference Signs List 1 electronic circuit 10 substrate 30 inductor 300 coil 301 input side end 302 output side end 310 metal magnetic member 311 to 314 surfaces 320 to 323 ferrite magnetic member 330, 332 input side external terminal , 331, 333 external terminals on the output side, 340, 341 metal plates

Claims (4)

a coil (300);
a metal magnetic member (310) formed by a soft magnetic metal so as to cover the coil and installed on a substrate ;
a non-conductive ferrite magnetic member ( 323 ) made of a ferrite magnetic material through which at least one of the coil input end (301) and the coil output end (302) passes ;
a non-grounded metal plate (340) disposed between the metal magnetic member and the ferrite magnetic member in contact with the metal magnetic member on the side opposite to the substrate side of the metal magnetic member;
a non-grounded metal plate (341) disposed between the metal magnetic member and the ferrite magnetic member on the substrate side of the metal magnetic member;
an inductor (30) comprising: An inductor (30) according to claim 1 , wherein said ferrite magnetic member is formed by a mixture of said ferrite magnetic material and a binder holding said ferrite magnetic material . An inductor (30) according to claim 1 or 2 , wherein the metallic magnetic member is formed by a mixture of the soft magnetic metal and a binder holding the soft magnetic metal . An electronic circuit (1) comprising an inductor according to any one of claims 1-3 .

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