JP2008210978A - Wire-wound electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire-wound electronic component capable of reducing a direct-current resistance value (Rdc) and having a small eddy-current loss. <P>SOLUTION: The wire-wound electronic component 2 comprises a drum core 4 having a wire 10a provided by an insulating coating, a core part 4a wound by the wire 10a so as to form a coil part 10, and a pair of flanges 4b, 4c formed on the both sides in an axial direction of the core part 4a and having an external diameter larger than that of the core part 4a. The thickness in the axial direction of the respective flanges 4b, 4c are 0.22 to 0.26 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wound electronic component that can reduce a direct current resistance value (Rdc) and has low eddy current loss.

  As a wire-wound electronic component such as an inductor, a transformer, and a choke coil, for example, a wire-wound electronic component shown in Patent Document 1 below is known. A wire-wound electronic component includes a drum core having a core portion in which an insulation-coated wire is wound so as to form a coil, and a pair of flange portions formed on both sides in the axial direction of the core portion. It has.

In patent document 1, as shown to the paragraph 0018, there exists general description that the axial direction thickness of a collar part is 0.2-0.5 mm. However, in particular, in a wound electronic component having a short axial length of the drum core, there is a problem that Rdc cannot be reduced when the axial thickness of the collar portion is greater than a predetermined value. Conventionally, there has been a demand for a simple means for reducing eddy current loss in a wound electronic component.
JP 10-163033 A

  The present invention has been made in view of such a situation, and an object thereof is to provide a wound electronic component that can reduce a direct current resistance value (Rdc) and has low eddy current loss.

In order to achieve the above object, a wire wound electronic component according to the present invention includes:
An insulated wire;
A core portion around which the wire is wound so as to form a coil;
A winding-type electronic component comprising a drum core formed on both sides in the axial direction of the core, and having a pair of flanges having a larger outer diameter than the core;
The axial thickness of each said collar part is 0.22-0.26 mm.

  When the thickness of the jaw is thinner than 0.22 mm, the particle size of the ferrite granule constituting the heel part is about 50 μm or less, so that the granule density is lowered and the mechanical strength in the heel part may be lowered. There is. Further, when the thickness of the jaw portion becomes thicker than 0.26 mm, it is necessary to relatively shorten the axial length of the winding core portion, and the number of turns of the wire in the first layer is reduced, so that the same inductance is obtained. It is necessary to increase the number of layers. Therefore, in some cases, the winding portion of the outermost layer wire becomes larger than the flange portion, which is contrary to the demand for downsizing of parts.

  In the present invention, since the axial thickness of the flange portion is 0.22 to 0.26 mm, the axial length of the core portion can be relatively increased when the overall length of the drum core is not changed. Become. Therefore, it is not necessary to increase the number of winding layers in the winding core, and the size of the part can be reduced.

  In the present invention, since the axial thickness of the flange portion can be reduced, the axial width of the external electrode formed on the outer peripheral portion of the flange portion can also be reduced. Therefore, eddy current that may be generated in the external electrode can also be reduced, and eddy current loss can be reduced. If the eddy current loss can be reduced, a decrease in inductance can be prevented. The external electrode needs to be formed so as not to expose the connection line in view of the appearance of the component.

  Preferably, the total length of the drum core in the axial direction is 1.5 to 2.4 mm. The present invention is particularly effective when the axial length of the drum core is short.

  Preferably, the outer diameter of the wire coated with insulation is 25 to 130 μm. In the present invention, since the axial thickness of the flange portion is 0.22 to 0.26 mm, the axial length of the core portion can be relatively increased when the overall length of the drum core is not changed. Become. Therefore, if the number of turns is the same so as not to change the inductance, the outer diameter of the wire wound around the core portion can be increased, and the DC resistance value (Rdc) can be reduced.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is a schematic longitudinal sectional view of a wound electronic component according to an embodiment of the present invention,
FIG. 2 is a schematic perspective view of the wire wound electronic component shown in FIG.

  As shown in FIGS. 1 and 2, a coil chip component 2 as a wound electronic component according to an embodiment of the present invention has a drum core 4 as a core (core material). The drum core 4 is made of a ferrite material. The drum core 4 has a core portion 4 a in which a wire 10 a constituting the coil portion 10 is wound along the axial direction X of the core 4.

  A first flange portion 4b and a second flange portion 4c are formed integrally with the first end portion and the second end portion, which are both ends in the axial direction X of the core portion 4a. The outer dimensions of the first flange 4b and the second flange 4c are larger than the outer diameter of the core 4a.

  The cross section of the core part 4a is not particularly limited, and may be a rectangular cross section, a circular cross section, or other cross sectional shapes. The cross-sectional shape of the 1st collar part 4b and the 2nd collar part 4c is square shape, such as a rectangular cross section. Although the different size may be sufficient as the 1st collar part 4b and the 2nd collar part 4c, Preferably it is the same size. For example, when the first flange portion 4b and the second flange portion 4c are rectangular cross sections, the vertical and horizontal dimensions are (0.8 to 1.7 mm) × (0.8 to 1.7 mm).

  In this embodiment, axial thickness t1 and t2 of the 1st collar part 4b and the 2nd collar part 4c are 0.22-0.26 mm, respectively. These axial thicknesses t1 and t2 may be slightly different, but are preferably substantially the same. The total length L0 of the core 4 including the axial thicknesses t1 and t2 of the first flange 4b and the second flange 4c is preferably 1.5 to 2.4 mm.

  A method for producing the drum core 4 having the first flange portion 4b, the second flange portion 4c, and the core portion 4a is not particularly limited. However, the drum core 4 is usually obtained integrally by compression molding a magnetic material such as ferrite powder.

  As shown in FIG. 1, the wire 10a is wound around the core part 4a. In the present embodiment, the wire 10a is wound around the winding core portion 4a with three winding layers, and the coil portion 10 is formed.

  The connecting portions 10b and 10c formed at both ends of the wire 10a constituting the coil portion 10 are connected to the base electrode film 20 at the outer peripheral positions of the flange portions 4b and 4c. The wire 10a is, for example, a wire in which a copper wire is covered with an insulating film such as urethane resin, and the wire diameter (outer diameter) of the wire 10a is preferably 25 to 130 μm.

  The base electrode film 20 is obtained, for example, by applying and forming an electrode paste containing conductive particles such as Ag, glass frit and binder resin, followed by drying and baking. Although the drying temperature in that case is not specifically limited, 100-300 degreeC and baking temperature are about 600-800 degreeC. The film thickness of the base electrode layer 20 after the baking treatment is not particularly limited, but is usually about 20 to 30 μm.

  After the base electrode layer 20 and the connecting portions 10b and 10c are connected, the outer resin portion 50 is formed by molding a resin in the outer circumferential concave portion of the core portion 4a where the coil portion 10 is formed. The outer diameter of the exterior resin portion 50 is approximately the same as the outer diameter of the flange portions 4b and 4c.

  The resin constituting the exterior resin portion 50 is not particularly limited, and examples thereof include an epoxy resin, a phenol resin, and a polyester resin. Preferably, a diallyl phthalate resin mixed with magnetic powder is used. As the magnetic powder mixed in the exterior resin portion, for example, Ni—Zn ferrite is used. The exterior resin portion 50 is formed by means such as injection molding.

  As shown in FIG. 1, after the exterior resin part 50 is formed, a conductive paste film (conductive electrode film) 30 is formed so as to cover the outer peripheral surface and the outer end surface of the base electrode layer 20. The conductive paste film 30 is formed by applying a conductive paste and then drying it. The conductive paste in this case includes, for example, conductive particles such as Ag, a binder resin, a solvent, and the like. Drying after the application of the conductive paste is performed under temperature conditions such that the exterior resin portion 50 does not deteriorate.

  The ratio of the binder resin per unit area of the conductive paste film 30 is preferably 5 area% or more and 35 area% or less. In addition, as a method of setting the ratio of the binder resin per unit area of the conductive paste film 30 to 5 area% or more and 35 area% or less, with respect to the entire conductive particles and binder resin included in the conductive paste, What is necessary is just to let the ratio of binder resin be 5 volume% or more and 35 volume% or less. If the ratio of the binder resin in the conductive paste is too small, the adhesion between the conductive paste film 30 and the base electrode layer 20 may be deteriorated, and the conductive paste film 30 may crack, and the ratio of the binder resin is too large. The completed coil chip component 2 may cause a solder explosion phenomenon. However, by setting the ratio of the binder resin in the conductive paste within the above range, these problems can be prevented.

  Preferably, the unit area is 100 μm × 100 μm. Preferably, the resin is uniformly dispersed within the unit area of the conductive paste film.

  Preferably, the particle diameter of the conductive particles is 0.5 to 10 μm, and the distance between the conductive particles in the conductive paste film 30 is 20 μm or less. More preferably, the particle diameter of the conductive particles is 1 to 6 μm, and the distance of the conductive particles in the conductive paste film 30 is 12 μm or less.

  That is, in the conductive paste film 30, the conductive particles are distributed at such a density that the conductive particles are in contact with each other, and a large gap (gap larger than the conductive particles) is not generated between the conductive particles. The binder resin can be uniformly dispersed in the electric paste film 30, and the binder resin can be prevented from agglomerating to a size larger than that of the conductive particles. As a result, the adhesion between the conductive paste film 30 and the outer electrode film 40 formed on the conductive paste film 30 can be improved, and the solder explosion phenomenon can be effectively prevented.

  The thickness of the conductive paste film 30 is not particularly limited, but is preferably about 20 to 50 μm, and more preferably 20 to 30 μm.

  After forming the conductive paste film 30, as shown in FIG. 1, an outer electrode film 40 made of a plating film is formed outside the conductive paste film 30. Although the outer electrode film 40 may be a single layer, in the present embodiment, the outer electrode film 40 is formed of a three-layer plating film. The outer electrode film 40 includes, for example, three layers of a Cu plating film, a Ni plating film formed so as to cover the Cu plating film, and a Sn plating film formed so as to cover the Ni plating film.

  Preferably, each of the Cu plating film and the Ni plating film has a thickness of 4 to 8 μm. Preferably, the Sn plating film has a thickness of 3 to 9 μm.

  As described above, the strength of each plating film can be improved by making each plating film thicker than before. As a result, each plating film (outer electrode film 40) can be prevented from being lost or damaged, and a solder explosion phenomenon can be prevented. The conductive paste film 30 and the outer electrode film 40 constitute the outer electrode 60.

  In this embodiment, since the axial thickness of the flange portion is 0.22 to 0.26 mm, the axial length of the core portion 4a is relatively long when the overall length L0 of the drum core 4 is not changed. It becomes possible to do. Therefore, it is not necessary to increase the number of winding layers in the core part 4a, and the component 2 can be downsized.

  Further, in the present embodiment, since the axial thicknesses t1 and t2 of the flange portions 4b and 4c can be reduced, as shown in FIG. 2, the external electrode 60 formed on the outer peripheral portion of the flange portions 4b and 4c. The width in the axial direction X can also be reduced. Therefore, the eddy current I that may be generated in the external electrode 60 by the magnetic flux M of the coil can also be reduced, and eddy current loss can be reduced. If the eddy current loss can be reduced, a decrease in inductance can be prevented. The external electrode 60 needs to be formed in order to prevent the connecting portions 10b and 10c shown in FIG.

  Further, in the present embodiment, since the axial thicknesses t1 and t2 of the flange portions 4b and 4c are 0.22 to 0.26 mm, when the total length L0 of the drum core 4 is not changed, the core portion 4a is relatively. It becomes possible to lengthen the axial direction length. Therefore, if the number of turns is the same so as not to change the inductance, the outer diameter of the wire wound around the core part 4a can be increased in the range of 25 to 130 μm. As a result, the DC resistance value ( Rdc) can be reduced.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention. For example, the specific cross-sectional structure of the coil chip component according to the present invention is not limited to the embodiment shown in FIG. 1 and may have various aspects.

Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.
Example 1

  As Example 1, a coil chip component 2 shown in FIGS. 1 and 2 was produced. In the manufacture of the coil chip component 2, the drum core 4 has the flanges 4b and 4c having axial thicknesses t1 and t2 of 0.24 mm, a total length L0 of 1.9 mm, and the flanges 4b and 4c. A core 4 having a horizontal cross-sectional dimension of 1.2 mm × 1.2 mm and a core section 4a having a horizontal cross-sectional dimension of 0.5 mm × 0.5 mm was used. Further, as the wire 10a, a wire having an outer diameter of 0.08 mm obtained by coating a copper wire with a urethane resin was used.

A wire was wound around the core portion 4a of the core 4 so that the inductance was 10 μH, and the coil chip component 2 shown in FIGS. 1 and 2 was produced. The DC resistance (Rdc) of the coil chip part 2 was measured and found to be 0.368Ω.
Comparative Example 1

As the drum core 4, the core 4 having axial thicknesses t1 and t2 of the flange portions 4b and 4c of 0.325 mm and a wire having an outer diameter of 0.075 mm are used, respectively. Coil chip parts were produced. The DC resistance (Rdc) of the coil chip part was measured and found to be 0.424Ω.
Evaluation 1

By comparing Comparative Example 1 and Example 1, it was confirmed that the DC resistance (Rdc) of Example 1 could be reduced by about 13% compared to Comparative Example 1.
Example 2

A coil chip component was manufactured in the same manner as in Example 1 except that a wire was wound around the core portion 4a of the core 4 so that the inductance was 22 μH. The DC resistance (Rdc) of the coil chip part was measured and found to be 0.874Ω.
Comparative Example 2

A coil chip component was manufactured in the same manner as in Comparative Example 1 except that a wire was wound around the core portion 4a of the core 4 so that the inductance was 22 μH. The DC resistance (Rdc) of the coil chip part was measured and found to be 1.239Ω.
Evaluation 2

  By comparing Comparative Example 2 and Example 2, it was confirmed that the DC resistance (Rdc) of Example 2 could be reduced by about 30% compared to Comparative Example 2.

FIG. 1 is a schematic longitudinal sectional view of a wire wound electronic component according to an embodiment of the present invention. FIG. 2 is a schematic perspective view of the wire wound electronic component shown in FIG.

Explanation of symbols

2 ... Coil chip parts (winding type electronic parts)
DESCRIPTION OF SYMBOLS 4 ... Drum core 4a ... Core part 4b ... 1st collar part 4c ... 2nd collar part 5 ... Element main body 10 ... Coil part 10a ... Wire 10b, 10c ... Connection part 20 ... Base electrode film 30 ... Conductive paste film 40 ... Outer electrode film 50 ... Exterior resin part 60 ... External electrode

Claims (3)

An insulated wire;
A core portion around which the wire is wound so as to form a coil;
A winding-type electronic component comprising a drum core formed on both sides in the axial direction of the core, and having a pair of flanges having a larger outer diameter than the core;
A wound-type electronic component in which the axial thickness of each of the flanges is 0.22 to 0.26 mm.   The wire-wound electronic component according to claim 1, wherein an overall length of the drum core in the axial direction is 1.5 to 2.4 mm.   The wound electronic component according to claim 1, wherein an outer diameter of the insulation-coated wire is 25 to 130 μm.

Images