JP2016048725A - Common mode filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a common mode filter capable of making high impedance characteristics compatible with excellent frequency characteristics.SOLUTION: The common mode filter includes: an insulator 10 including side surfaces 10A and 10B; two planar coils 20A and 20B which are embedded in the insulator 10 and disposed so as to confront each other while vertically holding an insulation layer 11M therebetween; an external electrode 41 for an inner end; an external electrode 42 for an outer end; two inner lead-out parts 31A and 31B which connects inner end portions of the planar coils 20A and 20B with the external electrode 41 for the inner end; and two outer lead-out parts 32A and 32B which connect outer end portions of the planar coils 20A and 20B with the external electrode 42 for the outer end. A shortest distance from the side surface 10A to the planar coils 20A and 20B is longer than a shortest distance from the side surface 10B to the planar coils 20A and 20B.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laminated common mode filter.

  As the need for portable electronic devices and thin electronic devices expands, common mode filters used for differential transmission circuits of these electronic devices are also required to be smaller and thinner, and to cope with higher frequencies. Is also sought. As devices become smaller in common mode filters, the coil diameter becomes the determining factor for component size. Patent Document 1 discloses that when a common mode filter is miniaturized, a coil having a shape close to a quadrangle similar to a chip shape is formed.

JP 2013-45784 A

  In miniaturization of common mode filters, it is considered important to use an insulator more effectively than ever. In addition to miniaturization, it is necessary to maintain and improve electrical characteristics. In view of the above, an object of the present invention is to provide a common mode filter that can achieve both high impedance characteristics and excellent frequency characteristics.

As a result of intensive studies by the present inventors, the present invention having the following characteristics has been completed.
(1) an insulator having at least one pair of opposing side surfaces, and two planar coils that are embedded in the insulator and arranged to face each other with an insulating layer perpendicular to the side surfaces sandwiched from above and below, The inner end external electrode formed on one side surface of the pair of opposing side surfaces, the outer end external electrode formed on the other side surface of the pair of opposing side surfaces, and the inside of each planar coil Two inner lead portions for connecting the outer end portion and the inner end external electrode, and two outer lead portions for connecting the outer end portion and the outer end external electrode of each planar coil, The shortest distance from one side surface to the planar coil is larger than the shortest distance from the other side surface to the planar coil. Common mode filter (2) When viewed in plan from one side surface, the external electrode is closer to the innermost circumference of the planar coil. (1) located outside Common mode filter.
(3) The two inner lead portions are formed on (A) a plane above the upper planar coil or (B) a plane below the lower planar coil, and the two inner lead portions and 2 The minimum value of the distance between two planar coils is larger than the distance between the two planar coils.
(4) Both of the two inner lead portions are formed on a plane above the upper planar coil, and the minimum value of the distance between the two inner lead portions and the two planar coils is less than the interval between the two planar coils. Large common mode filter (1).
(5) The insulator has a non-magnetic body and magnetic bodies disposed on both upper and lower sides of the non-magnetic body, the two planar coils are in the non-magnetic body, and the two inner lead portions are the non-magnetic body and the magnetic body. The common mode filter according to any one of (1) to (4).

  ADVANTAGE OF THE INVENTION According to this invention, the common mode filter which can make a high impedance characteristic and the outstanding frequency characteristic compatible is provided. Specifically, the capacitance between the inner end external electrode and the planar coil can be kept low, and even if the device is downsized, both improvement in frequency characteristics and high impedance characteristics can be achieved. In a preferred embodiment, the outer electrode is disposed outside the innermost circumference diameter of the planar coil, so that the capacity between the outer electrode and the planar coil can be kept low, thereby increasing the inner circumference diameter, and the frequency. Impedance can be increased without degrading characteristics. In another preferred embodiment, since the distance between the inner lead portion and the planar coil is large, the capacity between them can be kept low, and the frequency characteristics can be improved. In a further preferred embodiment, since the inner lead portion is above the upper planar coil, it is possible to reduce the height of the insulator while keeping the capacitance low. In another preferred embodiment, the height of the insulator can be further reduced while the capacitance is kept low by providing the inner lead portion between the non-magnetic material and the magnetic material.

It is a schematic diagram of the common mode filter of this invention. It is a model top view of the common mode filter of this invention. It is a schematic cross section of the common mode filter of the present invention. It is a schematic cross section of the common mode filter of the present invention.

  Hereinafter, the present invention will be described in detail with appropriate reference to the drawings. However, the present invention is not limited to the illustrated embodiment, and in the drawings, the characteristic portions of the invention may be emphasized and expressed, so that the accuracy of the scale is not necessarily guaranteed in each part of the drawings. Not.

  1A and 1B are schematic views of a common mode filter of the present invention. FIG. 1A is a plan view and FIG. 1B is a cross-sectional view. According to the present invention, the common mode filter has a laminated structure in which the two planar coils 20A and 20B sandwich the insulating layer 11M from above and below. In the present invention, the concept of “upper and lower” is for the convenience of explanation of the laminated structure and for the convenience of the directionality of each configuration described later, and does not limit the order of the steps at the time of manufacture. It is not intended to limit the directionality or arrangement during use. Therefore, which of the two planar coils 20A and 20B is recognized as “upper” is arbitrary. Each of the planar coils 20A and 20B has an inner end 21 and an outer end 22 of a spiral coil. Regarding the laminated structure including two planar coils, the aspect and the manufacturing method can refer to the related art as appropriate, and the manufacturing examples are introduced in the examples described later.

  The planar coils 20 </ b> A and 20 </ b> B exist so as to be embedded in the insulator 10. The insulator 10 has at least one pair of opposing side surfaces 10A and 10B. These side surfaces 10A and 10B are substantially perpendicular to the “up and down” direction defined above. Preferably, the insulator 10 has a rectangular parallelepiped shape, and this shape is substantially equal to the overall size of the common mode filter.

  The insulator 10 preferably includes a nonmagnetic body 11 and a magnetic body 12, and more preferably, the magnetic body 12 is disposed on both upper and lower sides of the nonmagnetic body 11. Preferably, the two planar coils 20 </ b> A and 20 </ b> B are positioned so as to be embedded in the nonmagnetic body 11. Examples of the material of the magnetic body 12 include, but are not limited to, Ni—Zn—Cu ferrite, Mn—Zn—Cu ferrite, or a metal magnetic material according to necessary magnetic permeability and frequency characteristics. Examples of the material of the nonmagnetic material 11 include Zn ferrite, Zn—Cu ferrite that can be sintered at low temperature, borosilicate glass, a mixture of borosilicate glass and crystalline silica, or a resin. Regarding the insulator 10, the prior art can be referred to as appropriate for its mode and manufacturing method, and manufacturing examples are introduced in the examples described later.

  External electrodes 41 and 42 are formed on the side surfaces 10A and 10B. The external electrodes are classified into an inner end external electrode 41 that is electrically connected to the inner end 21 of the planar coil 20 and an outer end external electrode 42 that is electrically connected to the outer end 22. it can. Electrical connection between the respective end portions 21 and 22 and the external electrodes 41 and 42 is performed by a later-described lead portion. Of the side surfaces 10A and 10B described above, the surface on which the inner end external electrode 41 is formed is referred to as "one side surface 10A", and the surface on which the outer end external electrode 42 is formed is referred to as "the other side surface 10B". . The specific shapes and manufacturing methods of the external electrodes 41 and 42 can be referred to as needed in the prior art or the examples described later, and typically include manufacturing by plating technology.

  The lead portions 31 and 32 are connected and electrically connected to the end portions 21 and 22 of the planar coils 20A and 20B and the external electrodes 41 and 42, respectively. Each extraction part 31 * 32 consists of a conductor. The inner lead portion 31 is connected to the inner end portion 21 and the inner end external electrode 41 of the planar coils 20A and 20B. The outer lead portion 32 is connected to the outer end portion 22 of the planar coils 20A and 20B and the outer end external electrode.

  According to the present invention, the shortest distance L2 from one side surface 10A to the planar coil 20 is larger than the shortest distance L1 from the other side surface 10B to the planar coil 20. In other words, in the insulator 10, the planar coils 20 </ b> A and 20 </ b> B are arranged so as to be biased so as to approach the outer end external electrode 42. As a result, the capacitance between the inner end external electrode 41 and the planar coil 20 can be kept low, and even if the device is downsized, both improvement in frequency characteristics and high impedance characteristics can be achieved. FIG. 2 is a schematic plan view of the common mode filter of the present invention. The planar coil 20 is closer to the outer end external electrode 42 than in the embodiment of FIG. 1, and the above-described value of L2 / L1 is improved. From the viewpoint of making the effect more effective, the value of L2 / L1 is preferably 1.2 to 2.0.

  When viewed in plan from one side surface 10 </ b> A, the external electrode is preferably located outside the innermost circumference of the planar coil 20. Here, “plan view from one side surface 10A” means a perspective view when the other side surface 10B is viewed from one side surface 10A, and “the external electrode is located outside the innermost periphery of the planar coil. "Means that the position of the external electrode 41 on the other side surface 10B when viewed in plan from one side surface 10A is located outside the innermost round position of the planar coil. That is, as shown in FIG. 2, the symbol b that is the distance between the two external electrodes 41 on the other side surface 10 </ b> B is greater than the symbol a that is the distance between the innermost circumferences of the planar coils. Further, the external electrode 42 on the other side surface 10A is located in the same manner.

  FIG. 1B is a schematic cross-sectional view of the common mode filter of the present invention. Preferably, as shown in FIG. 1B, the outer lead portions 32A and 32B are formed in the same plane as the respective planar coils 20A and 20B.

  The inner lead portion 31 is usually formed on a different surface from the planar coil 20 for the convenience of pattern formation. Connection conductors 51 </ b> A and 51 </ b> B exemplified by via technology can be used for connection between the planar coil 20 and the inner lead portion 31. As a preferred embodiment of the planar coil 20, the inner lead portion 31 is formed on (A) a plane above the upper planar coil 20A or (B) a plane below the lower planar coil 20B. . The two inner lead portions 31A and 32B may be formed on the same plane, or may be formed on different planes as shown in FIG. As shown in FIG. 1B, the inner lead portion 31A connected to the upper planar coil 20A is further above the coil 20A and is connected to the lower planar coil 20B. 31B may be further below the coil 20B.

  FIG. 3 is a schematic cross-sectional view of the common mode filter of the present invention. As shown in FIG. 3, according to a particularly preferred aspect, the two inner lead portions 31 are both formed in a plane above the upper planar coil 20 </ b> A. At this time, the two inner lead portions 31 may be formed on different planes, or the two inner lead portions 31 may be formed on the same plane as in the form of FIG. 3 (in the latter case, In the cross-sectional view as shown in FIG. 3, only one inner drawer is visible.) Even if it is considered that both of the two inner lead portions 31 are formed on a plane that is “below” the “lower” planar coil 20B, the entire common mode filter is viewed upside down. , “The two inner lead portions are both formed in a plane above the upper planar coil”, the above-mentioned particularly preferable embodiment is included.

  FIG. 4 is a schematic cross-sectional view of the common mode filter of the present invention. In the preferred embodiment of the present invention, the minimum value of the distance between the two inner lead portions 31 and the two planar coils 20 is larger than the distance between the two planar coils 20. The distance between the two planar coils 20A and 20B is indicated by the symbol c in FIG. As the “distance between the two inner lead portions and the two planar coils”, four distances are assumed. These four distances can be obtained by using the symbols depicted in FIG. 1B, “a distance between the inner lead portion 31A and the planar coil 20A”, “a distance between the inner lead portion 31A and the planar coil 20B”, and “inner side”. “Distance between the lead portion 31B and the planar coil 20A” and “Distance between the inner lead portion 31B and the planar coil 20B”. In this preferred embodiment, attention is paid to the minimum value of these distances. Referring to FIG. 4 again, in this embodiment, the two inner lead portions 31 are formed on the same plane. Therefore, the “distance between the two inner lead portions and the two planar coils” is “the distance between the inner lead portion 31 and the planar coil 20A” and “the distance between the inner lead portion 31 and the planar coil 20B”. The former (symbol d), which is assumed to have a short distance, is evaluated as the “minimum value” described above. In this preferred embodiment, the distance of the symbol d is longer than the distance of the symbol c. Since the distance between the inner lead portion 31 and the planar coil 20 is large, the capacity between them can be kept low, and the frequency characteristics can be improved.

  In the form of FIG. 4, the inner lead portion 31 is between the non-magnetic body 11 and the magnetic body 12. The presence of the inner lead portion 31 between the nonmagnetic material 11 and the magnetic material 12 is preferable in that the height of the insulator 10 can be further reduced while keeping the capacitance low. Preferably, only one of the two inner lead portions 31 may be between the non-magnetic body 11 and the magnetic body 12, and in view of the advantages, more preferably, the two inner lead portions 31 Both are between the non-magnetic body 11 and the magnetic body 12.

  The common mode filter of the present invention is characterized by the arrangement of planar coils and lead portions, and the specific method for manufacturing a device having the above-described characteristics is not particularly limited, and the prior art can be referred to as appropriate. For example, Ag or the like is exemplified as the material of the conductor of the planar coil 20, and a printing method using a paste or the like is illustrated as a non-limiting example as a manufacturing method thereof, for connecting the planar coil 20 and the inner lead portion 31 on different planes. For the formation of the connection conductor 51, through-hole technology and the like can be referred to as appropriate. With respect to the creation of the through hole, for example, a technique such as punching with a mold or drilling by laser processing is not limited. As a typical manufacturing example of a common mode filter, a magnetic sheet and a non-magnetic sheet that are precursors of each insulating layer are obtained, a conductor paste or the like is printed on the sheet, and through holes are appropriately provided to form a coil. Are formed by pressure bonding, removing the resin (debinding), and firing. Specific examples of these production methods will be described in detail in the following examples.

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

First, in order to obtain a magnetic sheet, a slurry is prepared by adding butyral resin and a solvent to Ni-Zn-based ferrite fine powder (permeability 900) after calcined and pulverized mainly containing FeO ₂ , ZnO, and NiO. did. This slurry was applied with a doctor blade so as to have a constant thickness, dried, and cut into a predetermined size to produce a magnetic sheet. Next, in order to obtain a nonmagnetic sheet, a butyral resin and a solvent were added to the borosilicate glass powder to prepare a slurry. The slurry was applied with a doctor blade so as to have a constant thickness, dried, and cut into a predetermined size to produce a non-magnetic sheet. Through holes were formed at predetermined positions in the nonmagnetic sheet. Next, an Ag paste was printed on the nonmagnetic sheet using a screen plate and dried to obtain a pattern of a planar coil (the number of turns: 5.5 t), each lead portion, and the connecting conductor. Next, the magnetic material sheet, the nonmagnetic material sheet, and the nonmagnetic material sheet on which each pattern was printed were laminated and press-bonded. After cutting this to a predetermined size, it was subjected to binder removal treatment at 500 ° C. for 1 hr, and baked in an atmospheric furnace at 890 ° C. for 2 hr to form a laminate chip. An Ag paste for each external electrode was applied to the side surface of the obtained laminate chip by a printing method, and was baked in air at about 600 ° C. for 1 hour to form a terminal electrode. Each terminal electrode was subjected to nickel electrolytic barrel plating and then subjected to solder electrolytic barrel plating to form each external electrode. In this way, common mode filters of Examples and Comparative Examples were obtained.

The size of the insulator of the common mode filter obtained in each example and comparative example is as follows.
Examples 1 to 6, Comparative Example 1 1.2 mm × 1.0 mm × 0.5 mm,
Example 7 1.2 mm × 1.0 mm × 0.45 mm,
Example 8 1.2 mm × 1.0 mm × 0.4 mm
The schematic diagram of each product is as follows.
Examples 1 to 4, Comparative Example 1 FIG.
Embodiment 5 FIG.
Example 6 FIG. 3
Example 7 FIG. 4
Example 8 ... not shown

  Tables 1 and 2 show the dimensions of the common mode filters obtained in the examples and comparative examples. Each dimension was adjusted by adjusting the sheet thickness of the nonmagnetic material.

表１におけるａ、ｂは図２に示す寸法であり、ｃ、ｄは、図４に示す寸法である。

In Table 1, a and b are dimensions shown in FIG. 2, and c and d are dimensions shown in FIG.

表２におけるＬ１、Ｌ２は図１に示す寸法である。

L1 and L2 in Table 2 are the dimensions shown in FIG.

(Evaluation)
Table 3 summarizes the product characteristics of the common mode filter of each example and comparative example.

  For measurement of impedance and cut-off frequency, an Agilent network analyzer E5071C was used. The peak value of the impedance is a common mode impedance, and this peak value is obtained. The cut-off frequency is obtained by measuring the insertion loss of the transmission characteristics of the differential mode. The frequency at which the insertion loss was 3 dB was taken as the cutoff frequency.

DESCRIPTION OF SYMBOLS 10: Insulator 11: Nonmagnetic body 12: Magnetic body 20: Planar coil 31: Inner extraction part 32: Outer extraction part 41: External electrode for inner ends 42: External electrode for outer ends

Claims (5)

An insulator having at least one pair of opposing sides;
Two planar coils embedded in an insulator and disposed so as to face each other with an insulating layer perpendicular to the side surface sandwiched from above and below,
An inner end external electrode formed on one side surface of the pair of opposing side surfaces;
An outer electrode for an outer end formed on the other side surface of the pair of opposing side surfaces;
Two inner lead portions connecting the inner end of each planar coil and the inner end external electrode;
Two outer lead portions connecting the outer end portion of each planar coil and the outer end external electrode;
The shortest distance from one side to the planar coil is greater than the shortest distance from the other side to the planar coil.   The common mode filter according to claim 1, wherein the external electrode is located outside the innermost circumference of the planar coil when viewed from one side.   The two inner lead portions are formed in (A) a plane above the upper plane coil, or (B) a plane below the lower plane coil, and the two inner lead portions and the two plane coils. The common mode filter according to claim 1, wherein a minimum value of the distance between and is larger than a distance between two planar coils.   The two inner lead portions are both formed in a plane above the upper planar coil, and the minimum value of the distance between the two inner lead portions and the two planar coils is larger than the distance between the two planar coils. Item 2. The common mode filter according to Item 1.   The insulator has a non-magnetic body and magnetic bodies disposed on both upper and lower sides of the non-magnetic body, the two planar coils are in the non-magnetic body, and the two inner lead portions are between the non-magnetic body and the magnetic body. The common mode filter according to any one of claims 1 to 4, wherein:

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