JP3103787B2 - Magnetic shield type chip inductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductor for a transmission device used in a communication device or the like, and more particularly to a magnetic shield type chip inductor having a narrow tolerance.

[0002]

2. Description of the Related Art As a prior art of a magnetic shield type chip inductor formed in a square shape, as shown in FIG. 1, a winding 6 is wound around a square drum core 1 having a square flange 1a and a flange base plate 1b at both ends. And cover the square case core 2 for magnetic shielding around the flange 1 a and the winding 6.
The terminal of the winding is pulled out to the exposed terminal electrode 3,
A resin in which a resin is injected and fixed between the cores is disclosed in Japanese Patent Publication No. Hei 3-6804 and Japanese Utility Model Application Laid-Open No. Sho 61-156212. As shown in FIG. 2, terminal electrodes 3 are formed at both ends of a base plate 1b of a rectangular drum core 1 having the same structure as that shown in FIG. Japanese Patent Application Laid-Open No. 2-88211 discloses that the leading end of the wire 6 is wound and fixed with the solder 4.

[0003]

However, the prior art
Kind of inductor drum core is difficult to hold and winding
There was a difficult problem. In addition, in the case of the conventional structure shown in FIG. 1, when the rectangular drum core and the rectangular case core for shielding are combined, as shown in FIG. The relative position of the core 2 is shifted and the gap between the two is apt to fluctuate, and it is difficult to realize an inductor having a narrow tolerance, which is difficult to use. Another problem is that since the drum core and the case core are in contact with each other over a large area, the magnetic path does not become a sufficiently open magnetic path, and the DC superimposition characteristic deteriorates. Therefore, it is important to minimize the contact between the two and improve the DC bias characteristics while maintaining a high inductance. Also,
In the case of the conventional drum core shown in FIG. 2, the terminal electrode 3 is formed on the flange 1b as shown in FIG. 2A, and the lead end of the winding 6 is wound therearound as shown in FIG. 2B. Since the soldering is performed by soldering, there is a problem that the flatness of the bottom surface is poor and the bonding between the electrode and the circuit pattern on the printed circuit board is not stable.
Therefore, an object of the present invention is to solve these problems.

[0004]

The present invention solves the above problems by the following means. (1) The present invention, a stepped portion is provided on the base plate, interposed with square drum core having a casing core and mating flange on the other end, a gap between the front notated flange around the drum core more becomes, the de a rectangular casing core covered as
Protruding from the base plate outside the step of the ram core
A groove is formed on two sides, and an electrode is formed around the groove and around it
Then, a winding is applied to the drum core, and
Wrap around the two sides including the groove, and wrap it around the upper surface of the electrode.
Only solder the wires and square the bottom of the square case core
A gap is formed by floating from the base plate of the drum core.
Magnetically shielded chip inductor with resin fixed between
To provide.

[0005] (2) The present invention may further be provided respectively a recess for chucking the two different side portion and the two sides of the base plate.

[0006]

The ferrite core for an inductor and the chip inductor using the same according to the present invention are provided on a substrate provided on a base plate.
Since it has a locking groove, it can be used to
Is easier to do. Also fits the drum core on the base plate
A step is provided to engage with the matching case core.
-Easy positioning of the score and winding on the base plate
The tangled part at the beginning does not interfere with the winding work
Thus, the winding becomes easy. In addition, four or more mountain-shaped small protrusions are provided inside and outside the case core, and these are shared with the steps.
As a result, variations due to the eccentricity of the case core can be suppressed, and a chip inductor having high inductance characteristics with excellent narrow tolerance can be provided. In addition, by employing a structure in which the bottom edge of the case core is floated from the base plate and fixed with resin, it is possible to provide a shielded chip inductor having a high rated current that hardly causes magnetic saturation.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. 3A and 3B show an embodiment of a square drum core, wherein FIG. 3A is a plan view, FIG.
(C) is a side view. 4A and 4B show an embodiment of a square case core combined with the square drum core of FIG. 3, wherein FIG. 4A is a bottom view and FIG. 4B is an inverted front view. For the square drum core and the square case core, a well-known ferrite sintered body having a high magnetic permeability obtained by molding and firing metal oxide powder is used.

[0008] In FIG. 3, square drum core 1 is more an upper flange 1a of the square, and an intermediate angular columnar winding core, and a step portion 1d of the same shape and the same size as the upper flange 1a, a base plate 1b Become. As can be seen from (b), a concave groove 1e for winding a wire of a winding is formed in the bottom surface of the two protruding sides of the base plate 1b in parallel with the peripheral surface of the step portion 1d. These concave grooves 1e have such a size that the twisted wire is not exposed on the lower surface of the base plate 1b.
Also, as can be seen from (a), an R-shaped notch 1f is provided to limit the width of the winding wire. Further, as shown in (a), the other two sides of the base plate project outward beyond the surface of the step 1d by the thickness of the case core. That is, the periphery of the step 1d of the base plate 1b provides a surface for supporting the lower end of the case core. These other two sides have two chucking recesses 1c for attachment to the jig of the automatic winding device.

In FIG. 4, a rectangular case core 2 is a rectangular cylinder having four walls with a substantially constant thickness. The case core 2 preferably has notches 2b at four corners on the bottom side. These cutouts are provided to pull out the wire at the winding end or inject resin to fix the square case core and the square drum core. At the substantially center of the four surfaces of the inner wall, a vertically extending chevron 2
a is formed. In the example shown in the figure, these chevron projections 2a extend to the entire height of the drum core. However, when the square case core 2 is fitted to the square drum core 1, the square flange 1a of the case square drum core 1 and the square flange 1a It may be formed only at the portion facing the step 1d. These chevron projections are used to prevent surface contact between the cores 1 and 2 and may be sufficiently low, for example, about 50 to 100 μm is sufficient.

FIG. 5 is a front view of a magnetic shield type inductor formed by combining a square drum core 1 and a square case core 2, and FIG. 6 is a perspective view thereof. A conductive paste is applied to the concave groove 1e of the square drum core 1 and the protruding portion of the base plate 1b near the concave groove 1e, baked, plated to form an electrode 3, and automatically wound using the chucking concave portion 1c. Winding 6 is applied by a machine, and a wire lead-out portion 6a at the end thereof is drawn out and wound around the two protruding sides of the base plate 1b through the concave groove 1e to form a wire flaking portion 6b. For electrical connection and mechanical fixing between the electrode 3 and the electrode 3. Wire tying part 6
Since b is not soldered to the lower surface, the lower surface of the base plate 1b is flat, which facilitates mounting on a printed circuit board.

Next, the rectangular case core 2 is fitted to the rectangular drum core 1 having the windings and the electrodes, and the lower edge of the rectangular case core 2 is sandwiched by the base plate 1b.
a, 5b is injected and heated after being pre-cured with ultraviolet light,
Fix the cores together. Due to the presence of the chevron projection 2a, only a linear or point-like contact occurs between the flange 1a and the step 1d of the square drum core 1 and the square case core 2. For this reason, the magnetic path formed by the two cores is a closed magnetic path close to the open magnetic path, and a high-inductance chip inductor can be obtained because magnetic ferrite having a high magnetic permeability is used. In addition, since it is relatively close to the open magnetic circuit, the rated current is relatively high. In addition, the gap between both cores is angled projection 2
a is kept constant by a, so that an inductance with a narrow tolerance is obtained.

FIG. 7 shows a case where the mounting structure shown in FIGS. 5 and 6 is slightly modified to form an inductor for a high rated current. In the figure, the two cores are positioned by a jig so that a slight gap 7 is formed between the base plate 1b of the square drum core 1 and the bottom surface of the square case core 2, and fixed with an ultraviolet curing resin. As a result, the magnetic path becomes an open magnetic path, so that a chip inductor having a high rated current can be obtained with a narrow tolerance.
In the above description, the chevron projection is provided on the side of the square case core, but may be provided on the flange of the square drum core and the peripheral surface of the step portion.

[0013]

As described above, the ferrite core for an inductor and the chip inductor using the same according to the present invention are provided with a step for fitting with a square case core on a base plate, and further, inside the case core. Since four or more mountain-shaped small protrusions are provided on the front, rear, left, and right, variations due to eccentricity of the case core can be suppressed, and a chip inductor having excellent narrow inductance and high inductance characteristics can be provided. In addition, by employing a structure in which the bottom edge of the case core is floated from the base plate and fixed with resin, it is possible to provide a shielded chip inductor having a high rated current that hardly causes magnetic saturation. In addition, 2 exposed from the case core of the base plate.
Since a concave groove is formed in the bottom of the side for winding the lead wire of the winding, the bottom surface of the base plate becomes flat, and mounting on a printed circuit board can be facilitated. Further, since the chucking concave portions are provided in the base plate, the winding operation can be facilitated.

[Brief description of the drawings]

1A and 1B show a conventional shield type chip inductor, wherein FIG. 1A is a plan view and FIG. 1B is a sectional view.

2 (a) is a bottom perspective view, and FIG. 2 (b) is a bottom perspective view with a winding applied thereto, showing a drum core of another conventional shield type chip inductor.

FIG. 3 shows an embodiment of a square drum core of the present invention,
(A) is a plan view, (b) is a front view, and (c) is a side view.

FIG. 4 shows an embodiment of the square case core of the present invention,
(A) is a bottom view and (b) is an inverted side view.

FIG. 5 is a front view of the shielded chip inductor of the present invention.

FIG. 6 is a perspective view of a shield type chip inductor of the present invention.

FIG. 7 is a front view of a shielded chip inductor according to a modification of the present invention.

[Explanation of symbols]

 Reference Signs List 1 square drum core 1a upper flange 1b base plate 1c chucking recess 1d step 1e concave groove 1f R-shaped notch 2 square case core 2a angled protrusion 2b notch 3 electrode 4 solder 5a, 5b UV curable resin 6 winding 6a Wire lead-out part 6b Wire tying part 7 Clearance

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-191226 (JP, A) Japanese Utility Model Showa 64-39612 (JP, U) Japanese Utility Model Showa 57-183713 (JP, U) Japanese Utility Model Showa 64- 35720 (JP, U) JP-A 3-113810 (JP, U) JP-A 6-11316 (JP, U) JP-A 7-18420 (JP, U) Jiko 56-19372 (JP, Y2) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01F 17 / 04,27 / 02 H01F 27 / 24,27 / 29

Claims (2)

(57) [Claims] 1. A stepped portion is provided on the base plate, so as to be interposed and square drum core having a casing core and mating flange on the other end, a gap between the front notated flange around the drum core more will, the Dora the square case core covered
2 projecting from the base plate outside of the stepped portion of the arm core
Forming a groove on the side, forming an electrode around the groove and around the groove, applying a winding to the drum core, winding a lead wire of the winding around the two sides including the groove, forming an electrode; Solder the wire only to the top surface and square the bottom of the square case core
A gap is formed by floating from the base plate of the drum core.
A magnetic shield type chip inductor with a gap fixed by resin . 2. The magnetic shield type chip inductor according to claim 1, wherein chucking concave portions are provided on two sides of the base plate different from the two sides.