JPH0794342A - Surface-mount type coil - Google Patents

Abstract

PURPOSE:To provide a surface-mount type coil wherein a drum-type core is used and which is lessened in height and enhanced in joining strength between a drum-type core and a pad. CONSTITUTION:A high-frequency transformer of a surface-mount type coil is equipped with a drum-type core 32 wound with a winding 31 and a pad 37 which is possessed of a housing hole 34 where one flange 33b of the drum-type core 32 is housed and where lead terminals 36 connected to the end 35 of the winding 31 are fixed, wherein the housing hole 34 is provided with an engaging means 40 used for fastening the flange 33b of the drum-type core 32. Therefore, the low drum-type core 32 and the pad 37 are enhanced in joining strength between them by the engaging means 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mounting type coil such as a high frequency transformer and a choke coil which are surface mounted on a circuit board of an electronic device.

[0002]

2. Description of the Related Art In recent years, there is a strong consumer demand for miniaturization and high performance of electronic devices, and accordingly, transformers, choke coils, etc. of coil components occupying a relatively large volume in electronic components mounted on electronic circuit boards. Has been developed with a drum-shaped core that is suitable for surface mounting while achieving a small size and a thin shape.

For example, in a transformer, particularly in a high frequency transformer used in a DC / DC converter, an inverter or the like, a shape in which a flange portion is provided at each of an upper end and a lower end of a columnar coil winding shaft portion which is generally provided in a vertical direction. A surface-mounted type in which a winding is wound around the coil winding shaft portion of the drum type core made of the magnetic material is often used.

FIG. 6 is a sectional view showing the structure of the conventional surface mount type high frequency transformer.

In the figure, when the drum type core 1 is used as a high frequency transformer, since a plurality of windings are wound, a plurality of lead terminals for winding the windings and connecting to the mounting board are required. . Therefore, conventionally, a metal-made lead terminal 3 is protruded from a side surface, bent into an S-shape, and a pedestal 4 made of synthetic resin is separately prepared and fixed so that its tip is in contact with the surface of a mounting substrate. One flange 5 of the drum-shaped core 1 is adhered and fixed to substantially the center of the upper surface of the lead terminal 3
The operation of winding the end portion of the winding wire 8 around the base portion 7 of the base, winding it around the winding shaft portion of the drum core 1 and winding it around other lead terminals is repeated, and then the lead terminals 3 are solder-dipped to achieve high frequency. The transformer 10 was constructed. Further, the choke coil has the same configuration.

Since the drum type core 1 generally has a high resistivity, a powder of ferrite (nickel zinc ferrite, manganese zinc ferrite, etc.), which is an oxide magnetic material used as a high frequency magnetic core material, is pressed. Molded,
Made by sintering.

On the other hand, a low-height coil having a structure in which the height of the surface-mounted coil using the drum core as described above is further reduced is disclosed in Japanese Utility Model Laid-Open No. 90409/1993.

FIG. 7 is an exploded perspective view for explaining the structure of the low-profile coil, and FIG. 8 is a vertical sectional view of the low-profile coil.

In FIG. 7 and FIG. 8, a coil 25 has a pedestal 13 in which projecting lead terminals 11a to 11f and a through hole 12 are arranged, a ferrite cover 14 inserted in the through hole 12, and arranged. The structure is provided with a drum-type ferrite core 16 housed in the ferrite cover 14 and around which the winding 15 is wound.

In the figure, the ferrite cover 14 is inserted into and fixed to the inner peripheral surface 17 of the through hole 12 of the pedestal 13. In this respect, although no fixing means for the joint portion 18 is disclosed, it is considered that the fixing means is usually performed by an adhesive.

In the above structure, the ferrite cover 14 is lowered by the height of the pedestal 13 (the drum type ferrite core 16 is naturally lowered), and the height is further reduced.

The ferrite cover bottom surface 19 and the pedestal bottom surface 20 have lead-out grooves 21a to 21f for guiding the winding end portions 15a to 15f to the lead terminals 11a to 11f.
2a to 22f are provided respectively.

[0013]

However, in the surface mount type coil 25 having a structure in which the ferrite cover 14 is inserted into the through hole provided in the pedestal, which is known from Japanese Utility Model Laid-Open No. 3-90409, the through hole 12 is not formed. The inner peripheral surface 23 is provided perpendicular to the pedestal 13.

In this structure, when an adhesive is used to fix the ferrite cover 14 to the pedestal 13 as described above, a slight joining portion 18 between the through hole inner peripheral surface 23 of the pedestal and the outer peripheral surface of the ferrite cover 18 is used. It will be fixed in. In this respect, when the lead-out grooves 21a ..., 22a ... Provided in the ferrite cover 14 and the pedestal 13 have a large cross-sectional area, the contact area of the joint portion 18 is further reduced.

In the fixed state, the bonding strength between the ferrite cover 14 and the pedestal 13 is generally weak, and when the bonding strength of the adhesive is weakened due to vibration or other impact, the ferrite cover 14 and the drum-type ferrite core 16 are inserted from the through hole 12 into the pedestal 1.
There was a problem that there is a great risk of falling out of 3.

The above situation is not the surface mount type coil structure disclosed in Japanese Utility Model Laid-Open Publication No. 90409/1990, which has the ferrite cover 14 as a constituent element, but the one flange portion 17 of the drum type ferrite core 16 is directly passed through the through hole 12. Insert into the inner surface 2
Even in the surface-mounted coil having the structure fixed to No. 3, there is no doubt that the same problem occurs in the above-mentioned configuration in which the pedestal is simply provided with the through hole.

Further, when the ferrite cover 14 is inserted into the through hole 12 of the pedestal 13, there is a problem that the ferrite cover 14 is not properly inserted and may be inclined or may further enter from the bottom surface of the pedestal and protrude from the bottom surface. .

Further, since the drum-type ferrite core 16 is axisymmetric, in the step of fixing the drum-type ferrite core 16 to the pedestal 13 after winding the winding, the lead-out direction of the winding is set at the time of assembling the winding. There was a problem that we could not decide uniquely.

Furthermore, the completed surface mount type coil 25 described above.
Since is generally symmetrical, there is a problem that it takes time to confirm the lead terminals 11a to 11f when mounting the circuit board.

The present invention has been made in view of the above circumstances, and mainly realizes the reduction of the height of the surface mounting type coil using the drum type core and enhances the bonding strength between the drum type core and the pedestal. A surface mount coil having a structure is provided.

[0021]

According to the present invention, there are provided (1) a drum core around which a winding is wound, a housing hole for housing one flange portion of the drum core, and an end of the winding. A surface mount coil having a pedestal to which a plurality of lead terminals for connecting parts are fixed, and a locking means for locking one flange of the drum core in a storage hole of the pedestal. (2) The surface mount coil according to (1), characterized in that the locking means is made of the same material as the lead terminal. By doing so, (3) a plurality of lead terminals having a drum core around which a winding is wound and a housing hole for housing one flange portion of the drum core and connecting the ends of the winding are provided. In a surface mount type coil with a fixed pedestal, (4) The drum type core is provided with a positioning means for mutual positioning in one of the flange portion of the drum type core and the accommodating hole of the pedestal. The above-mentioned object is achieved by providing a surface-mounted coil according to (3), characterized in that the other flange portion of the core is provided with a direction display means.

[0022]

In the present invention, since the one flange portion of the drum-shaped core is completely inserted into the accommodation hole (in other words, the through hole 12 in the conventional example) provided in the pedestal, the thickness of the flange portion is equal to the thickness of the flange portion. Contributes to lowering the height of the coil.

Further, since the storage hole is provided with a locking means for locking the collar portion, the drum core is stably placed by the locking means, and the drum-shaped core penetrates the storage hole and falls off. There is no such thing.

Further, when the collar portion is fixed to the housing hole with an adhesive, the bonding area is larger by the locking means than the conventional case of the housing hole having only a vertical peripheral surface. Is improved.

When the locking means is made of the same material as the lead terminal, the lead terminal is an iron-based or copper-based frame, so that the strength is high although the locking means is thin. Therefore, the height can be further reduced as compared with the case where the locking means is the same synthetic resin as the pedestal.

Further, in the case of a surface mount type coil having positioning means for mutual positioning in one of the collar portion of the drum type core and the accommodating hole of the pedestal, the drum type core is preliminarily assembled at the time of assembly. Since it is easy to fit the pedestal to each other, the drum core is correctly placed in the accommodation hole in a predetermined positional relationship and is not inclined.

Further, in the case of the surface mount coil having the other collar portion (the collar portion not accommodated in the accommodating hole) of the drum type core provided with the direction indicating means, the positions of the lead terminal and the winding are uniquely provided. Since the relationship can be grasped at a glance, it becomes easy to confirm the directivity of the surface mounting coil, which is a symmetrical component at the time of winding assembly and circuit board mounting.

[0028]

Embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the same reference numerals are used for members having the same shape.

FIG. 1 is an exploded perspective view for explaining a high frequency transformer as a typical example of the surface mount type coil according to claim 1 of the present invention, and FIG. 2 is a vertical sectional view of the high frequency transformer.

1 and 2, the high frequency transformer 3
Reference numeral 0 designates a drum core 32 around which the winding 31 is wound, and a housing hole 3 for housing one flange portion 33b of the drum core 32.
And a pedestal 37 to which a plurality of lead terminals 36 for connecting the ends 35 of the windings 31 are fixed, the surface mounting type coil having a drum shape in a storage hole 34 of the pedestal 37. The structure is characterized in that a locking means 40 for locking one flange portion 33 of the core 32 is provided.

More specifically, the drum type core 32 described above.
Is obtained by pressure molding and sintering a general ferrite powder as a magnetic material, has flanges 33a and 33b at both ends, and has a core part around which a winding is wound in the center. In addition, the one flange portion 33b is provided with an uneven portion 39 that fits with the locking means 40 provided in the storage hole 34 of the pedestal.

Ferrite, which is the material of the drum core 32, is an oxide magnetic material and has a relatively large resistance and a small high frequency loss, and is therefore widely used as a magnetic material especially for high frequencies. There are types such as nickel ferrite, nickel cobalt ferrite, nickel zinc ferrite, manganese zinc ferrite and the like.

Next, the pedestal 37 is made of synthetic resin and is made by injection molding of, for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), phenol resin or the like.

Further, the lead terminals 36a ...
This is a solder-plated terminal made of iron-based metal such as 2-alloy or copper-based metal such as phosphor bronze and copper containing iron.

The winding 31 is an insulating coated conductive wire such as an enamel coated conductive wire or a polyurethane coated conductive wire, and is wound as primary and secondary windings in an overlapping manner.

In the surface-mounted coil 30 having the above structure, the one flange portion 33b of the drum coil 32 is completely accommodated in the accommodation hole 34 of the pedestal 37, so that the thickness of the collar portion is lower than the coil height. It is clear that it will contribute to

Further, locking means 40 is provided in the storage hole 34.
As a part of the inner peripheral surface 41 as a protruding portion
Set to 0. ) Is made of the same material (synthetic resin) as the pedestal.

The partially projecting portion 40 is the drum core 3
There is no particular limitation as long as the shape is such that it fits into the concave-convex portion 39 of the second collar portion 33b and the entire collar portion 33b is stored and locked in the storage hole 34. In this embodiment, the drum-shaped core 32 is stably locked by the partially protruding portions 40 facing each other.

Next, the surface mount type coil according to claim 2 starts with a metal frame (hereinafter referred to as a lead frame) 43 of continuous integral lead terminals 36a ... By press molding as shown in the perspective view of FIG. More drum-shaped core collar 3
A locking means 40 'for locking 3b is additionally provided so that the partially projecting portion 40' of the housing hole is made of the same material as the lead terminals 36a at the same time when the pedestal is molded (the above-mentioned iron-based or copper-based metal). Formed in.

The lead frame 43 has a thickness of 0.5 m.
Although it is m or less, it is stronger than synthetic resin.

Therefore, it is apparent that the thickness can be made thinner than the locking means 40 of the pedestal made of synthetic resin of the first embodiment, which contributes to further height reduction of the coil.

Next, FIG. 4 is an exploded perspective view in which the drum type coil 45 and the pedestal 51 of the surface mount type coil 50 according to claim 3 of the present invention are separated, and FIG. 5 is a line AB of FIG. The corresponding vertical cross section of the said drum type core 45 and the pedestal 51 in a CD line is shown.

As is apparent from FIGS. 4 and 5, the surface mount type coil 50 is positioned in one of the flange portions 46b of the drum type core 45 and the accommodation hole 44 of the pedestal 51, respectively, by positioning means 47a for positioning each other. 47d, 48a to 48d
In addition, the inner peripheral surface 52 of the storage hole 44 is not perpendicular to the pedestal 51 but is provided with a taper so that the diameter gradually decreases toward the bottom surface side.

The positioning means 47a, 48a, ... are fitted to each other in a state where the one flange portion 46b of the drum core 45 is housed, so that the drum core 45 can be rotated while being housed in the housing hole 44. , Never tilt.

Further, the contact area between the drum-shaped core 45 and the pedestal 51 is increased by the positioning means and the locking means, and the joint strength between them is increased.

The positioning means 47a ..., 48a ...
If the arrangement of the groups is asymmetrical or the shapes and sizes of the groups are different, the drum core 4 is uniquely formed.
Needless to say, the positioning of the pedestal 5 and the pedestal 51 is performed.

Next, as shown in FIGS. 4 and 5, the surface mount coil according to claim 4 of the present invention has the other flange portion 46a of the drum core 45 (one which is not housed in the housing hole 44). Since it is located on the upper surface, which is the side viewed by the operator during surface mounting, it has a structure in which it is provided with the direction display means 53.

The direction display means 53 is provided by engraving or coating with a paint such as a red dot.

The direction indicating means 53 determines the lead-out direction of each winding at the time of winding the winding, and the positional relationship of the lead terminals 56a to 56h can be uniquely grasped at a glance during the surface mounting work of the coil. It becomes easy to confirm the directionality of the symmetrical coil.

In addition, as a reminder, the surface mount type coil according to the present invention covers all of the coil components including the drum type core and the pedestal for mounting the drum type core, the shape of the drum type core, and the number of lead terminals. Of course, the material of the pedestal and the like are not limited to those in the above-mentioned embodiment.

[0051]

Since the surface mount coil according to the present invention is constructed as described above, it has the following effects.

(1) The height of the flange of the drum core is reduced by the thickness of the flange, and the drum core is stably placed by the locking means, which has the excellent effect of improving the bonding strength. .

(2) Since the locking means made of the same material as the lead terminal can be made thin, it has an excellent effect that the height can be further reduced.

(3) Since the positioning means uniquely determines the positioning at the time of joining the drum core and the pedestal,
It has an excellent effect of being properly joined.

(4) The direction display means has an excellent effect that the direction can be easily confirmed during the winding winding work and the surface mounting work.

[Brief description of drawings]

FIG. 1 is an exploded perspective view for explaining a high frequency transformer as a typical example of a surface mount coil according to claim 1 of the present invention.

FIG. 2 is a vertical sectional view of the high frequency transformer.

FIG. 3 is a perspective view of a lead frame of a surface mount coil according to claim 2 of the present invention.

FIG. 4 is an exploded perspective view showing a drum type coil and a pedestal of a surface mount type coil according to claim 3 of the present invention.

FIG. 5 is a corresponding longitudinal section of the drum core and the pedestal taken along the lines AB and CD in the previous figure.

FIG. 6 is a sectional view showing a structure of a conventional surface mount type high frequency transformer.

FIG. 7 is an exploded perspective view for explaining the structure of a conventional low-profile coil.

FIG. 8 is a vertical sectional view of the low-profile coil.

[Explanation of symbols]

1, 32, 45 Drum type core 3, 36 Lead terminal 4, 37, 51 Pedestal 5, 17, 33a, 33b, 46a, 46b Collar part 7 Pedestal base part 8, 15, 31 Winding 10, 30, 50 Surface mounting Type coil 11a to 11f, 56a to 56h, 52a to 52h Lead terminal 12 Through hole 13, 37, 51 Pedestal 14 Ferrite cover 15a to 15f, 35 Winding end 16 Ferrite core 18 Joint 19 Ferrite cover bottom 20 Pedestal bottom 21a -21f Derivation groove 22a-22f Derivation groove 23 Through hole inner peripheral surface 25 Coil 34,44 Storage hole 39 Concavo-convex part 40,40 'Locking means 41 Inner peripheral surface 43 Lead frame 47a-47d, 48a-48d Positioning means 53 direction Display means

Claims (4)

[Claims] 1. A drum core around which a winding is wound, a housing hole for housing one flange portion of the drum core, and a plurality of lead terminals for connecting the ends of the winding are fixed. A surface mount coil including a pedestal, wherein the housing hole of the pedestal is provided with locking means for locking one flange portion of the drum core. 2. The surface mount coil according to claim 1, wherein the locking means is made of the same material as the lead terminal. 3. A drum core around which a winding is wound, a housing hole for housing one flange of the drum core, and a plurality of lead terminals for connecting the ends of the winding are fixed. A surface mount coil including a pedestal, characterized in that one of the flanges of the drum core and the storage hole of the pedestal are provided with positioning means for mutual positioning. coil. 4. The surface-mounted coil according to claim 3, wherein the other flange portion of the drum core is provided with a direction display means.