JP3508329B2 - Chip type noise filter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type noise filter, and more particularly to a chip type noise filter used for a power supply line, a signal line and the like.

[0002]

2. Description of the Related Art Conventionally, as a chip type noise filter of this type, there is a structure in which a coil 27 is wound around a core 21 of a bobbin 20 as shown in FIG. The bobbin 20 includes a core 21 and flanges 22 and 23 at both ends thereof, and a pair of input / output terminal electrodes 24 and 25 are provided at both ends of one flange 22 of the bobbin 20. The outer surface of the coil 27 is coated with an insulating resin, and the lead portions 28, 2 at both ends of the coil 27 are covered.
9 is electrically connected to each of the input / output terminal electrodes 24 and 25 by solder 30 or the like. Furthermore, the core 21
The coil 27 wound around is covered with an insulating resin 26 for protecting it, as shown in FIG.

The chip-type noise filter having such a structure has input / output terminal electrodes 24 and 25 at both ends of the collar 22.
Are used by connecting between the wiring patterns forming the signal lines of the printed wiring board.

[0004]

However, the chip type noise filter as described above has the coil 27 in the high frequency range.
Stray capacitance is generated between the wires and the coil does not function as a coil. Therefore, noise generated in the power supply line, the signal line, and the like cannot be removed.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a chip type noise filter capable of enhancing the noise removing effect in a high frequency range.

[0006]

According to the present invention, there is provided a bobbin having a collar on a core, an earth terminal electrode and a pair of input / output terminal electrodes provided on the collar of the bobbin, the core, and the earth terminal electrode. Both ends of the input / output terminal electrode are connected to the ground electrode, and the outer surface of the core electrode is covered with a resin containing a dielectric material. The core electrode is in contact with the surface of the ground electrode. A chip-type noise filter, comprising: a coil wound around the coil. Further, in the above chip type noise filter, the outer surface of the coil is covered with a conductive resin that is electrically conductively connected to the ground terminal electrode, or includes a dielectric material coated on the outer surface of the coil. In the chip type noise filter, a metal film is formed on the outer surface of the resin, and the metal film is in conductive contact with the surface of the ground electrode. Further, a bobbin provided with a collar on the core, a ground terminal electrode and a pair of input / output terminal electrodes provided on the collar of the bobbin, and both ends of each of the input / output terminal electrodes are connected and an outer surface is The coil is coated with a resin containing a dielectric material and wound around the core, and the conductive resin covers the coil. The conductive resin is conductively connected to the ground terminal electrode. Is a chip-type noise filter. Further, a bobbin provided with a collar on the core, a ground terminal electrode and a pair of input / output terminal electrodes provided on the collar of the bobbin, and both ends of each of the input / output terminal electrodes are connected and an outer surface is A coil coated with a resin containing a dielectric material and wound around the core; and a metal film formed on the outer surface of the resin containing the dielectric material coated on the outer surface of the coil, wherein the metal The film is a chip type noise filter, which is connected to the ground terminal electrode.

According to the chip-type noise filter of the present invention, the core is provided with the ground electrode, and the coil whose outer surface is coated with the resin containing the dielectric material is brought into contact with the surface of the ground electrode to attach to the core. Since it is wound, the ground electrode is connected to the ground terminal electrode and grounded, and the stray capacitance generated between the coil wires can be reduced, and moreover, the capacitance between the coil wire and the ground terminal electrode can be reduced. Can be formed. Further, the core is provided with a ground electrode, the outer surface is covered with a resin containing a dielectric material, and the outer surface of the coil wound around the core in contact with the ground electrode is covered with a conductive resin. Therefore, the ground electrode is electrically connected to the ground terminal electrode, and the conductive resin is electrically connected to the ground terminal electrode to be grounded to reduce the stray capacitance generated between the wires of the coil. A large capacitance can be formed between the coil wire and the ground terminal electrode. Further, the core is provided with a ground electrode, and the coil wound around the core in contact with the ground electrode has an outer surface coated with a resin containing a dielectric material, and the outer surface of the resin is covered with a metal. Since a film is formed, this metal film makes conductive contact with the ground electrode, this ground electrode is connected to the ground terminal electrode and grounded, and the stray capacitance generated between the wires of the coil can be reduced. Moreover, a capacitance can be formed between the coil wire and the ground terminal electrode. Further, although the ground electrode is not provided on the core, the outer surface is covered with a resin containing a dielectric material, and the outer surface of the coil wound around the core is covered with a conductive resin. This conductive resin is electrically connected to the ground terminal electrode and grounded to reduce the stray capacitance generated between the wires of the coil, and moreover, to form the capacitance between the wire of the coil and the ground terminal electrode.

Although the ground electrode is not provided on the core, the coil wound around the core has an outer surface coated with a resin containing a dielectric material, and the outer surface of the resin has a metal film. When this metal film is connected to the ground terminal electrode and grounded, the stray capacitance generated between the coil wires can be reduced, and the capacitance between the coil wire and the ground terminal electrode can be reduced. Can be formed.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view of an embodiment (1) of a chip type noise filter according to the present invention, in which a coil 9 is wound around a core 2 of a bobbin 1.
[Fig. 2] is a front view of the wound coil 9 of Fig. 1 covered with a resin 14. 3A and 3B are a perspective view and a bottom view of the bobbin 1 used in an embodiment (1) of the chip type noise filter of the present invention. FIG. 4 shows a coil 9 used in the chip type noise filter of the present invention shown in FIG.
FIG. As shown in FIGS. 3A and 3B, the bobbin 1 in the chip-type noise filter of this embodiment (1) includes a core 2 and collars 3 and 4 at both ends thereof. Has been formed. A pair of input / output terminal electrodes 5 and 6 is provided on one flange 3 of the bobbin 1 from the lower surface on the outer side of the opposite ends to the end surface. Further, there is a ground terminal electrode 7 between the input / output terminal electrodes 5 and 6, and the ground terminal electrode 7 is provided from the outer lower surface to the end surface to the inner upper surface of the collar 3. A ground electrode 8 connected to the ground terminal electrode 7 is provided on the surface of the core 2.

A coil 9 is wound around the core 2 in one layer in contact with the surface of the ground electrode 8.
In this coil 9, as shown in FIG. 1, the lead portions 10 and 11 at both ends are connected to the input / output terminal electrodes 5 and 6, respectively.
It is connected by solder 13 or the like. Further, the coil 9 wound around the core 2 is covered with a resin 14 such as an epoxy resin for protecting it, as shown in FIG.
The coil 9 is made of a wire 16 whose outer surface is coated with a resin 12 containing a dielectric material, as shown in the sectional view of FIG.

In the chip type noise filter having such a structure, the input / output terminal electrodes 5 and 6 at both ends of the collar 3 are connected between the wiring patterns forming the signal lines of the printed wiring board, and the input / output terminals are connected. The ground terminal electrode 7 between the electrodes 4 and 5 is used by connecting to a wiring pattern forming a ground line. According to this embodiment (1), the coil 9 whose outer surface is covered with the resin 12 containing the dielectric material is used.
Is contacted with the surface of the ground electrode 8 and wound around the core 2. Therefore, the ground electrode 8 is connected to the ground terminal electrode 7 and grounded, and the stray capacitance generated between the wires 16 of the coil 9 is generated. Can be made smaller, and moreover, a capacitance can be formed between the wire 16 of the coil 9 and the ground terminal electrode 7.

Next, another embodiment (2) of the present invention will be described. In this embodiment (2), in the chip-type noise filter of the above embodiment (1), the resin 14 for protecting the coil 9 wound around the core 2 is conductive instead of insulating resin such as epoxy resin. It is made of a conductive resin and is formed by conductively connecting the conductive resin to the ground terminal electrode 7. According to this embodiment (2), since the outer surface of the coil 9 wound around the core 2 is brought into contact with the surface of the ground electrode 8 and covered with the conductive resin, the ground electrode 8 is grounded. For the terminal electrode 7,
Further, the conductive resin is conductively connected to the ground terminal electrode 7 and grounded to reduce the stray capacitance generated between the wires 16 of the coil 9, and moreover, the wire 16 of the coil 9 and the ground terminal electrode. It is possible to form a larger capacity between 7 and 7.

Next, another embodiment (3) of the present invention will be described. In this embodiment (3), in the chip type noise filter of the above embodiment (1), as shown in the sectional view of FIG. 6, the entire outer surface of the resin containing the dielectric material coated on the outer surface of the coil 9 is used. Further, the metal film 15 is formed by plating or the like. According to this embodiment (3), since the metal film 15 is formed on the outer surface of the coil 9 and comes into contact with the surface of the ground electrode 8 and is wound around the core 2, the metal film 15 is formed. Conductive contact with the ground electrode 8, the ground electrode 8 is connected to the ground terminal electrode 7 and grounded, and the stray capacitance generated between the wires 16 of the coil 9 can be reduced. Capacitance can be formed between the ground terminal electrodes 7.

Next, another embodiment (4) of the present invention will be described. In this embodiment (4), in the chip-type noise filter of the above-mentioned embodiment (1), the bobbin is as shown in FIG.
The core 14 of the bobbin 1 shown in FIG. 1 is provided with no ground electrode 8 and the resin 14 for protecting the coil 9 wound around the core 2 is made of a conductive material instead of an insulating resin such as an epoxy resin. And is formed by electrically connecting the conductive resin to the ground terminal electrode 7. According to this embodiment (4), the core 2
Since the outer surface of the coil 9 wound around the coil 9 is covered with a conductive resin, the conductive resin is conductively connected to the ground terminal electrode and grounded, and the wire 1 of the coil 9 is
The stray capacitance generated between the electrodes 6 can be reduced, and further, a capacitance can be formed between the wire 16 of the coil 9 and the ground terminal electrode 7.

Next, another embodiment (5) of the present invention will be described. In this embodiment (5), in the chip-type noise filter of the above embodiment (1), the bobbin is as shown in FIG.
The core 2 of the bobbin 1 shown in FIG. 2 is provided with no ground electrode 8, and the outer surface of the resin containing the dielectric material coated on the outer surface of the coil 9 is plated with metal film 1
5 is formed, and this metal film 15 is formed by being electrically conductively connected to the ground terminal electrode 7 with solder or the like. According to this embodiment (5), since the metal film 15 is formed on the outer surface of the coil 9, the metal film 15 is connected to the ground terminal electrode 7 and grounded, and the wire 16 of the coil 9 is connected. The stray capacitance generated between them can be reduced, and moreover, a capacitance can be formed between the wire 16 of the coil 9 and the ground terminal electrode 7.

As described above, each of the chip type noise filters of the present invention shown in each of the embodiments can be used as a distributed constant type low pass filter having an equivalent circuit as shown in FIG.

The present invention is not limited to the contents described in the above embodiments, but can be arbitrarily changed within the scope not departing from the spirit of the present invention. For example, the brim provided on the core 2 is not limited to both ends of the core 2 and may be provided on one end of the core 2. Further, the input / output terminal electrodes 5 and 6 and the ground terminal electrode 7 may be provided at arbitrary positions on the collar 3. Further, the ground electrode 8 provided on the core 2 does not necessarily have to be provided on the entire surface of the core 2, but may be provided on the surface of the core 2 that contacts the coil 9 to be wound. In addition, the above-mentioned embodiments (1) and (3)
The insulating resin 14 covering the coil 9 wound around the core 2 in (5) is for protecting the coil 9 and is not necessarily provided.

Further, the coil 9 wound around the core 2 is not limited to the single winding as in the above embodiment, but may be a multi-layer winding. In the case of this multi-layer winding, particularly in Examples (3) and (5), the metal film 15 is formed on the entire outer surface of the resin containing the dielectric material with which the outer surface of the coil 9 is coated. The metal film 15 is grounded via the ground terminal electrode 7, and the stray capacitance generated between the wires 16 of the coil 9 can be uniformly reduced from the lower layer to the upper layer, and the noise removing effect in the high frequency range can be obtained. It is more enhanced and more preferable as a noise filter.

[0020]

As described above, according to the chip-type noise filter of the present invention, the stray capacitance formed between the wires 16 of the coil 9 can be made smaller than that of the conventional one, and the excellent high-frequency characteristics can be obtained. It can be used as a distributed constant type low-pass filter in which a capacitance is formed between the wire 16 of the coil 9 and the ground terminal electrode 7. Therefore, it is possible to realize a chip-type noise filter capable of enhancing the effect of removing noise generated in the power supply line, the signal line, and the like.

[Brief description of drawings]

FIG. 1 is a front view of a chip type noise filter according to an embodiment of the present invention, in which a coil is wound around a core of a bobbin.

FIG. 2 is a front view of the wound coil of FIG. 1 covered with resin.

FIG. 3 is a perspective view (a) and a bottom view (b) of a core used in a chip type noise filter according to an embodiment of the present invention.

4 is a cross-sectional view of a coil used in the chip-type noise filter of FIG.

5 is an equivalent circuit diagram of the chip type noise filter of FIG.

FIG. 6 is a cross-sectional view of a coil used in a chip type noise filter according to another embodiment of the present invention, in which a metal film is formed on the outer surface of the coil.

FIG. 7 is a front view of a conventional chip-type noise filter in which a coil is wound around a bobbin core.

8 is a front view of the wound coil of FIG. 7 covered with resin. FIG.

[Explanation of symbols]

1 ... Bobbin 2 ... core Three, four ... Tsuba 5, 6 ... Input / output terminal electrodes 7 ... Ground terminal electrode 8: Ground electrode 9 ... coil 10, 11 ... Lead part 12 ... Resin containing dielectric material 13 ... Solder 14 ... Resin covering the wound coil 15 ... Metal film

Claims (5)

(57) [Claims] 1. A bobbin having a collar on a core, an earth terminal electrode and a pair of input / output terminal electrodes provided on the collar of the bobbin, and a ground provided on the core in connection with the earth terminal electrode. An electrode and a coil wound around the core in contact with the surface of the ground electrode, the outer surface of which is connected to both ends of the input / output terminal electrode and which is covered with a resin containing a dielectric material; A chip-type noise filter comprising: 2. The chip type noise filter according to claim 1, wherein an outer surface of the coil is covered with a conductive resin which is conductively connected to the ground terminal electrode. 3. A metal film is formed on the outer surface of a resin containing a dielectric material coated on the outer surface of the coil, and the metal film is in conductive contact with the surface of the ground electrode. The chip type noise filter according to claim 1. 4. A bobbin having a collar on the core, a ground terminal electrode and a pair of input / output terminal electrodes provided on the collar of the bobbin, and both ends of each of the input / output terminal electrodes are connected, The outer surface is covered with a resin containing a dielectric material, and the coil is wound around the core, and the conductive resin covers the outer surface of the coil. The conductive resin is the ground terminal electrode. A chip-type noise filter, which is electrically conductively connected to. 5. A bobbin having a collar on the core, a ground terminal electrode and a pair of input / output terminal electrodes provided on the collar of the bobbin, and both ends of each of the input / output terminal electrodes are connected, The coil has an outer surface coated with a resin containing a dielectric material and is wound around the core, and a metal film formed on the outer surface of the resin containing the dielectric material coated on the outer surface of the coil. The chip-type noise filter, wherein the metal film is connected to the ground terminal electrode.