JP2004207371A - Surface mounting choke coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface mounting choke coil which can surely insulate a mounting substrate such as the printed wiring board and a core with a resin molding. <P>SOLUTION: The choke coil is formed of a core 11 with the upper part opened including a bottom surface 12 integrated with a projected magnetic core 15 at the upper surface and a circumferential wall 13 integrally projected at the circumference of the bottom surface, a winding 16 wound around the magnetic core, and a flat magnetic material 17 provided at the upper opening part of the core to cover the winding. This choke coil is mounted on the mounting substrate. A resin mold 18 is provided at the lower surface of the bottom surface of the core. This resin mold is provided with a terminal 21 connected to the terminal 16a of the winding. The mounting substrate and core are insulated with the resin mold. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultra-compact shield type surface mount choke coil.
[0002]
[Prior art]
2. Description of the Related Art In recent years, various electronic devices have been significantly multifunctional due to higher integration and higher frequency, and furthermore, have been reduced in size and weight. Looking at notebook PCs as highly integrated electronic equipment, multi-function, high-quality flows have resulted in large currents for each line that supplies power to recording devices and CPUs as CPU speeds up (improves processing capacity). Is progressing. As the current increases and the integration increases, heat generation on the circuit increases, and it is an important issue to suppress such heat generation.
[0003]
As a choke coil used in various electronic devices such as a conventional notebook personal computer, a soft magnetic core material such as a Ni-Zn-based ferrite, a Mn-Zn-based ferrite, or an Fe-based alloy powder magnet is used. A type using a core or the like has been commercialized.
[0004]
Ni-Zn ferrites have low DC bias characteristics due to low saturation magnetic flux density, but are excellent in high frequency characteristics due to high specific resistance. Since the saturation magnetic flux density of the powder magnetic flux of the Fe-based alloy is higher than that of the Ni-Zn-based ferrite, the DC superposition characteristics are excellent. However, since the specific resistance is low, there is a problem that the core loss rapidly increases at a high frequency.
[0005]
As a soft magnetic material that satisfies these requirements by improving these problems, there is Mn-Zn-based ferrite. However, in the case of the Mn-Zn based ferrite, although the DC superimposition characteristics and the core loss at high frequencies can be improved, the lower surface of the bottom portion of the choke coil mounted on the mounting board is now mounted on the mounting board with the progress of high integration. There is a problem that a pattern exists and insulation failure occurs between the mounting substrate and the magnetic body. Conventionally, as a measure for preventing such insulation failure, means such as using a bobbin or resin molding has been adopted.
[0006]
[Problems to be solved by the invention]
However, when a bobbin is used, the shape is greatly restricted, and the limit to recent miniaturization, or when a choke coil is resin-molded, stress is applied to the magnetic material when the resin is cured, which increases the core loss and There have been problems such as variations in inductance.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object a simple structure that can reliably insulate between a mounting board and a core and have a small inductance variation. It is to provide a mounting choke coil.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned object, the present invention is directed to a core having an upper opening having a bottom portion having a magnetic core portion integrally projecting from the top surface and a peripheral wall portion integrally provided around the bottom portion. And a winding wound around the magnetic core portion, and a plate-shaped magnetic body provided in an upper opening of the core so as to cover the winding, and is mounted on a mounting board. A coil, wherein a resin molded body is provided on a lower surface of a bottom portion of the core, a terminal connected to a terminal of the winding is provided on the resin molded body, and the mounting substrate and the core are insulated by the resin molded body. It is characterized by having done.
[0009]
According to a second aspect of the present invention, a core having an upper opening having a bottom portion and a peripheral wall portion integrally provided around the bottom portion, and a magnetic core portion are provided so as to cover the upper opening of the core, and a magnetic core portion is integrally formed on the lower surface. A surface mounted choke coil mounted on a mounting board, comprising a flat plate-shaped magnetic body provided and a winding wound around the magnetic core, wherein a resin molded body is provided on a lower surface of a bottom surface of the core. And a terminal connected to a terminal of the winding is provided on the resin molded body, and the mounting substrate and the core are insulated by the resin molded body.
[0010]
According to a third aspect, the resin molded body according to the first or second aspect has a bottom surface and a side wall, and the bottom surface and the side wall are provided with a large number of heat radiation holes. .
[0011]
According to the configuration, the mounting board such as a printed board and the core can be reliably insulated by the resin molded body, and moreover, by providing a large number of heat radiation holes in the bottom and side walls constituting the resin molded body, The heat radiation effect can be enhanced.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
1 and 2 show a first embodiment, FIG. 1 is an exploded perspective view of a surface mount choke coil, and FIG. 2 is a perspective view of a state where the surface mount choke coil is mounted on a mounting board.
[0014]
As shown in FIG. 1, a core 11 made of Mn—Zn-based ferrite has a rectangular bottom portion 12. A pair of peripheral wall portions 13 having arcuate concave portions 13a facing each other protruding upward are integrally formed on both ends of the bottom portion 12, and cutout portions 14 facing each other are provided on both sides of the bottom portion 12. Have been. Further, a columnar magnetic core portion 15 protruding upward is protruded from the center of the bottom portion 12 to form a core 11 having an upper opening.
[0015]
A winding 16 composed of an air-core coil is fitted to the magnetic core 15 of the core 11, and both ends 16a of the winding 16 are led out. Further, a plate-shaped magnetic body 17 made of Mn—Zn-based ferrite is provided so as to close the upper opening of the core 11, and both ends of the magnetic body 17 are formed on the upper end surface of the peripheral wall 13 of the core 11 by thermosetting. It is fixed with a synthetic resin adhesive. Notches 17 a corresponding to the notches 14 of the core 11 are provided on both sides of the magnetic body 17.
[0016]
Further, a resin molded body 18 is fixed to the lower surface of the bottom portion 12 of the core 11 with a thermosetting synthetic resin adhesive. The bottom surface portion 18a of the resin molded body 18 has a rectangular shape having substantially the same size as the bottom surface portion 12 including the peripheral wall portion 13 of the core 11, and both side plates 19 for closing the cutout portions 14 of the core 11 project upward on both side portions. The two end portions are provided with joining surfaces 19a to be joined to the peripheral wall portion 13.
[0017]
Further, a continuous groove 20 is provided from the lower surface of the resin molded body 18 to the outer surface of both side plates 19, and a terminal 21 is fixed to the groove 20. The terminal 21 is formed by bending a strip having a plate thickness substantially equal to the depth of the concave groove 20 into an L-shape. The lower bent portion 21 a of the terminal 21 protrudes from the lower surface of the bottom surface 18 a of the resin molded body 18, and the upper end protrudes above the side plates 19. The terminal 16a of the winding 16 is soldered to the protruding portion of the terminal 21 in a tangled state.
[0018]
The surface mounting choke coil thus configured is mounted on a mounting substrate 22 having a land pattern, as shown in FIG. 2, and a resin molded body 18 is provided on the lower surface of the bottom portion 12 of the core 11. Therefore, the mounting board 22 and the core 11 can be electrically insulated by the resin molded body 18.
[0019]
In addition, since the core 11 and the magnetic body 17 are formed of Mn-Zn-based ferrite, DC superimposition characteristics and core loss at high frequencies can be improved, and variations in inductance can be reduced. Moreover, even if a land pattern exists on the mounting substrate 22 due to the high integration, the mounting substrate 22 and the core 11 can be completely electrically insulated, and the reliability can be improved.
[0020]
In the above-described embodiment, the terminal 16a of the winding 16 is soldered in a state of being entangled with the protruding portion of the terminal 21. However, the terminal is provided with a cut portion to form a clip structure. May be pinched or fixed by spot welding, fusing welding, or the like.
[0021]
FIG. 3 shows a second embodiment, and the same components as those in the first embodiment are denoted by the same reference numerals and description thereof will be omitted. In the present embodiment, a large number of heat radiation holes 23 composed of small holes are provided in the bottom portion 18a of the resin molded body 18 and the side plates 19, and the other configuration is the same as that of the first embodiment.
[0022]
According to the present embodiment, a heat dissipation effect can be obtained in addition to the electrical insulation effect between the mounting board 22 and the core 11 of the first embodiment.
[0023]
FIG. 4 shows a third embodiment, in which the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, the magnetic core portion 15 is divided into upper and lower portions, the upper magnetic core portion 15a is provided integrally on the lower surface of the magnetic body 17, and the lower magnetic core portion 15b is provided integrally with the core 11.
[0024]
FIG. 5 shows the fourth embodiment, and the same components as those of the first and third embodiments are denoted by the same reference numerals and description thereof will be omitted. In the present embodiment, the resin molded body 18 is divided into two right and left parts so that a gap 24 is formed below the bottom part 12 of the core 11. This gap 24 has the effect of improving the heat radiation effect.
[0025]
FIG. 6 shows a fifth embodiment, in which the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, the winding is a rectangular copper wire edgewise wound winding 25, and the end of the winding 25 is a terminal 25a.
[0026]
【The invention's effect】
As described above, according to the present invention, it is possible to reliably insulate a core from a mounting substrate such as a printed board and the like by a resin molded body, and furthermore, to provide a large number of heat radiation to the bottom and side walls constituting the resin molded body. By providing the holes, the heat radiation effect can be enhanced.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a choke coil according to a first embodiment of the present invention.
FIG. 2 shows the same embodiment, and is a perspective view of a state in which a surface mount choke coil is mounted on a mounting board.
FIG. 3 is an exploded perspective view of a choke coil according to the second embodiment of the present invention.
FIG. 4 is an exploded perspective view of a choke coil, showing a third embodiment of the present invention.
FIG. 5 is an exploded perspective view of a choke coil according to a fourth embodiment of the present invention.
FIG. 6 is an exploded perspective view of a choke coil according to a fifth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Core, 12 ... Bottom part, 13 ... Peripheral wall part, 15 ... Magnetic core part, 16 ... Winding, 17 ... Magnetic body, 18 ... Resin molding, 21 ... Terminal, 23 ... Heat dissipation hole

Claims (3)

A core having an upper opening having a bottom surface having a magnetic core portion integrally projecting from the upper surface thereof and a peripheral wall portion integrally provided around the bottom surface portion; a winding wound around the magnetic core portion; A surface-mounted choke coil, comprising a flat magnetic body provided in an upper opening of the core so as to cover a wire, and mounted on a mounting board,
A resin molded body is provided on the lower surface of the bottom surface of the core, a terminal connected to the terminal of the winding is provided on the resin molded body, and the mounting substrate and the core are insulated by the resin molded body. Surface mount choke coil. A flat core having a bottom portion and a core having an upper opening having a peripheral wall portion integrally provided around the bottom portion, and a core provided to cover the upper opening of the core, and a magnetic core portion integrally projecting from the lower surface. A magnetic body, and a surface-mounted choke coil configured of a winding wound around the magnetic core portion and mounted on a mounting board,
A resin molded body is provided on the lower surface of the bottom surface of the core, a terminal connected to the terminal of the winding is provided on the resin molded body, and the mounting substrate and the core are insulated by the resin molded body. Surface mount choke coil. 3. The surface mount choke coil according to claim 1, wherein the resin molded body has a bottom surface and a side wall, and the bottom surface and the side wall are provided with a large number of heat radiation holes. .

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