JPH11288824A - Choke coil - Google Patents

Abstract

(57) [Problem] To provide a choke coil for a switching power supply used in various electronic devices, and to provide a thin, small, low-loss component for surface mounting that can be automatically mounted at low cost. Aim. SOLUTION: Magnetic cores 14 are incorporated from both sides of a molded coil having a surface mounting terminal portion 12 on the bottom surface of a molded body 13 holding a winding 11, and a leading end portion of a lead lead portion 11a of a wire constituting the winding 11 is attached. Bend to surface mount terminal 1
No. 2 was formed, and the surface mount terminal portion 12 was located on the lower surface of the magnetic core 14 and was substantially inside the projected area from above the magnetic core 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a choke coil for a switching power supply used in various electronic devices.

[0002]

2. Description of the Related Art In recent years, with the development of various portable electronic devices, market demands for miniaturization, thinning, high performance, low power consumption, and the like have increased. In particular, switching power supplies are required to be compatible with high-density mounting mainly by surface mounting and to reduce loss. In particular, choke coils, which are the main key parts that make up a switching power supply, are required to be thin, compact, low-loss, and inexpensive parts that can be surface-mounted. It's no exaggeration to say that you hold the key to meeting your needs.

As a conventional choke coil, those shown in FIGS. 23 to 26 are generally used.

Hereinafter, a conventional choke coil will be described with reference to FIGS.

FIG. 23 is an external view showing a conventional choke coil, FIGS. 24 and 25 are configuration diagrams showing other typical examples of the conventional choke coil, and FIG. 26 is a top view for explaining the conventional choke coil. is there. 23 to 26, 1 is a winding, 2 is a magnetic core, 3 is a terminal block base, 4 is an extraction pin,
Reference numeral 5 denotes a molded body case, 6 denotes a surface mounting terminal, 7 denotes a lead winding portion, 8 denotes a coil base, and 9 denotes a gap between the windings 1.

[0008] In FIG. 23 of the related art, after winding a winding 1 around a toroidal type magnetic core 2 is mounted on a terminal block base 3, a drawer pin 4 is pulled out from the terminal base 3 to complete the process.

FIG. 24 shows an example in which the structure of the toroidal coil of FIG. 23 has been devised so that it can be surface-mounted. After the surface-mounting terminals 6 have been previously attached to the molded body case 5 by insert molding or the like, similar to FIG. The manufactured toroidal coil is incorporated into the molded body case 5 and the lead winding portion 7 of the surface mount terminal 6 is formed.
Is completed by connecting the parts. Here, the molded body case 5 is used for improving the chucking property because the upper surface of the conventional toroidal coil has an uneven surface, so that chucking cannot be performed when automatically mounting the surface mount component.

FIG. 25 is another typical example devised as a surface-mountable choke coil.
After the same toroidal coil as described above is mounted on the coil base 8, the molded body case 5 is mounted from the upper surface to complete it, and the leading end of the lead 1 a of the winding 1 is used as the surface mounting terminal 10. .

Next, the structure of a conventional toroidal type coil will be described with reference to the top view of FIG. The toroidal coil winds the winding 1 around the magnetic core 2 as shown in FIG. That is, the cross-sectional area and the wire diameter of the winding 1 are determined by the inner circumference of the magnetic core 2.
Generally has a structure in which a gap 9 between the windings 1 is formed on the outer peripheral surface of the winding.

[0010]

However, the conventional structure shown in FIG. 23 does not have a surface mountable structure. In the configuration shown in FIGS. 24 and 25, the molded body case 5, the surface mounting terminals 6,
A device for combining additional components such as the coil base 8 is required. That is, there is a problem that the number of parts increases and assembly becomes complicated, so that the manufacturing cost also increases. Further, the conventional toroidal coil has a structure in which a gap 9 between the windings 1 is formed on the outer peripheral portion of the magnetic core 2 as shown in FIG. 26, so that a thick winding cannot be closely wound. For this reason, in a choke coil of the same volume, there is a problem that the cross-sectional area of the winding 1 is reduced and the resistance is increased.

An object of the present invention is to solve the above problems and to provide a thin, small, low-loss choke coil for surface mounting that can be automatically mounted in a choke coil, which is a main key part of a switching power supply, at low cost. And

[0012]

In order to solve the above-mentioned problems, a choke coil according to the present invention is provided by incorporating a magnetic core from both sides of a molded coil having surface-mounting terminals on the bottom surface of a molded body holding a winding. The leading end of the lead portion of the wire constituting the wire is bent to form a surface-mounting terminal portion, and the surface-mounting terminal portion is positioned so as to be on the lower surface of the magnetic core and substantially inside the projected area from above the magnetic core. It was made.

According to the above-described structure, the surface-mounting terminal portion is formed by using the tip of the winding, and the molding of the winding makes it possible to use extra parts such as a molded body case, a coil base, and a surface-mounting terminal. Since no parts are used, the number of parts can be reduced,
It has a simple structure with no connection between the surface-mounting terminal and the winding, thus reducing costs. In addition, by incorporating the magnetic core from both sides, and by providing the surface mounting terminal portion within the projected area of the core and the lower surface portion of the magnetic core, the thick wire can be wound tightly without any gap and the surface mounting terminal portion can be It is possible to draw out with the shortest distance, and it is possible to effectively use the lower surface of the magnetic core and the empty space within the projected area of the magnetic core, and it is possible to simultaneously reduce the resistance and reduce the size. Further, since the upper surface of the choke coil is not a winding having irregularities but a magnetic core or a molded body, chucking at the time of automatic mounting becomes easy.

[0014] Thus, the object of providing a thin, small, low-loss component that can be automatically mounted and is compatible with surface mounting at low cost can be achieved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a winding is formed by incorporating magnetic cores from both sides of a molded coil having a surface mounting terminal portion on the bottom surface of a molded body holding a winding. The surface-mounting terminal portion is formed by bending the end of the wire lead-out lead portion, and the surface-mounting terminal portion is positioned so as to be on the lower surface of the magnetic core and substantially inside the projected surface contact from above the magnetic core. In addition, since no extra parts such as a molded body case, a coil base, and a surface mount terminal are used, the number of parts can be reduced, and a simple structure without a connection part between the surface mount terminal and the winding can be achieved, thereby reducing costs. In addition, the thick wire can be wound tightly without any gap, the surface-mounting terminal can be pulled out from the lead-out lead at the shortest distance, and the free space in the projected area of the lower surface of the magnetic core and the magnetic core can be effectively used. Resistance and miniaturization can be realized at the same time. Further, since the upper surface of the choke coil is not a winding having irregularities but a magnetic core or a molded body, chucking at the time of automatic mounting becomes easy.

According to a second aspect of the present invention, in addition to the structure of the first aspect, the upper surface of the molded body incorporating the magnetic core is projected from the top surface of the magnetic core, and the choke coil is automatically mounted. In some cases, the protrusion can be chucked, so that the magnetic core can be prevented from being cracked or chipped during mounting, and the quality can be improved.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, the upper surface of the molded body in which the magnetic core is incorporated is made flat, and chuck errors during automatic mounting can be reduced. Productivity is improved.

According to a fourth aspect of the present invention, in addition to the configuration of the first aspect, a step portion for supporting at least a part of the back surface of the magnetic core is provided on the molded body, and the upper surface of the step portion is flat and the magnetic core is flat. Since the magnetic cores to be assembled from both sides can be incorporated in parallel without any step, the assemblability is improved and automation is facilitated.

According to a fifth aspect of the present invention, in addition to the configuration of the first aspect, the magnetic core incorporated from both sides is a flat type magnetic core having a thin back surface. Since the dimensions in the mounting direction can be reduced,
The mounting area on the board can be reduced without increasing the occupied volume of the choke coil.

According to a sixth aspect of the present invention, in addition to the configuration of the first aspect, the shape of the terminal forming portion can be fixed in advance even if the winding line shape changes greatly. Becomes easier. In addition, productivity can be improved because the shape can be set in advance to facilitate bending.

According to a seventh aspect of the present invention, in addition to the configuration of the first aspect, the front end of the winding is processed into a square or flat shape to form a surface mount terminal. The connection area between the printed circuit board and the printed circuit board is increased, so that the connection reliability and the stability during reflow mounting are improved.

According to an eighth aspect of the present invention, in addition to the configuration of the first aspect, the surface-mounting terminals are arranged in parallel with the winding width direction of the winding, and the winding is formed by molding with a molded body. Since the movable direction of the mold is parallel to the terminal when the mold is moved, the mold can be pulled out in two directions, and the mold structure design and manufacturing costs can be reduced.

According to a ninth aspect of the present invention, in addition to the configuration of the first or eighth aspect, the first fine bending at the time of forming the terminal is performed in the same plane as the lead portion of the winding. If this part is used as a fulcrum and the final bending is performed for the second time, it is possible to prevent the winding shape from being distorted due to bending stress that does not use space in the winding width direction. Can be smaller.

According to a tenth aspect of the present invention, in addition to the configuration of the first aspect, a step portion for supporting the outer leg portion of the magnetic core is provided on the molded body, and the outer leg portion of the magnetic core is provided with the step portion. Since the position is regulated by the portion, the displacement of the magnetic core in the rotational direction can be prevented.

According to an eleventh aspect of the present invention, in addition to the configuration of the first aspect, a concave portion is provided on the inner surface of the molded body into which the center magnetic leg of the magnetic core is inserted. Molding can be performed with the safety distance of more than a predetermined value secured,
The thickness of the molded body is not uneven, and the safety of the choke coil is improved.

According to a twelfth aspect of the present invention, in addition to the structure of the first aspect, a recess is formed on the lower surface of the molded body, and a space can be secured between the choke coil and the substrate. It can be used as a space for preventing residual cleaning agent and flux during reflow mounting, preventing excess solder from flowing in, and venting gas.

According to a thirteenth aspect of the present invention, in addition to the configuration of the first aspect, the outer shape of the molded body is set to be larger than the outer shape of the magnetic core, and the outer shape of the resin molded body has higher dimensional accuracy than the magnetic core. The external dimensions are determined by the part, and the external accuracy of the choke coil is improved.

According to a fourteenth aspect of the present invention, in addition to the structure of the first aspect, the side surface of the surface mounting terminal portion is exposed, and the solder fillet portion when mounted on a printed circuit board is provided on the side surface. Since it can be formed, the mounting strength on the substrate is improved.

According to a fifteenth aspect of the present invention, in addition to the configuration of the first or ninth aspect, after the lead-out lead portion of the winding is drawn substantially straight downward, the lead portion is pulled parallel to the winding width direction of the winding. Since the surface mounting terminal portion is formed by bending, the fine bending process is eliminated or further facilitated, so that the winding can be easily automated and the equipment cost can be reduced.

According to a sixteenth aspect of the present invention, in addition to the structure of the first aspect, the tip is bent after molding to form a surface-mounting terminal portion, and even when the wire diameter of the winding changes. Since it is not necessary to design the mold in consideration of the dimensions of the terminal forming portion, the design of the mold is facilitated.

According to a seventeenth aspect of the present invention, in addition to the structure of the first aspect, the cross-sectional shape of the center magnetic leg of the flat core is formed into a flat shape such as an ellipse or an ellipse. The degree of freedom in shape setting, such as the reduction in thickness and the reduction in the area occupied by the board, is expanded, and it becomes easier to respond to customer needs.

According to an eighteenth aspect of the present invention, in addition to the structure of the first aspect, a wire having a cross section having a high space factor, such as a square wire or a flat wire, is used as a winding. Since the cross-sectional area of the wire can be increased and the shape of the winding portion can also be changed, the range of responding to customer needs including lower resistance and flexibility in shape setting is further expanded.

The invention according to claim 19 of the present invention uses a copper wire having an insulating film having a circular cross section as the winding, so that the winding operation can be performed efficiently.

According to a twentieth aspect of the present invention, an inverted trapezoidal terminal block is integrally provided at a lower portion of a molded body, and surface mount terminal portions are disposed on tapered surfaces on the front and rear surfaces of the terminal block. The surface mounting terminal portion can be arranged in the tapered surface of the terminal block, and the size can be reduced.

According to a twenty-first aspect of the present invention, 30 to 60 are provided so that both ends of the winding project outward at the lower part of the winding.
The configuration is such that the surface mount terminal portion is drawn out at an angle of degrees and the front surface and the back surface of the terminal block of the molded body are pulled out, and the pitch of the surface mount terminal portion can be arbitrarily set.

According to a twenty-second aspect of the present invention, the surface-mounting terminal portions at both ends of the winding are arranged slightly apart from the tapered surfaces on the front and back surfaces of the terminal block of the molded body. In addition, the resin does not adhere to the surface-mounting terminals during the molding of the windings, so that the reliability during mounting can be improved.

According to the twenty-third aspect of the present invention, the tip of the surface-mounting terminal is bent to engage with the terminal block of the molded body, and the position of the surface-mounting terminal can be stably maintained. become.

According to a twenty-fourth aspect of the present invention, there is provided an engagement groove formed in a tapered surface on a front surface and a back surface of a terminal block of a molded body by narrowing a tip of a surface mounting terminal portion and bending it to form an engagement portion. , And the strength of the surface mounting terminal portion can be improved.

According to a twenty-fifth aspect of the present invention, a notch is provided inside the bent portion to form the surface-mounting terminal portion by bending both ends of the winding. The bending accuracy can be prevented from lowering due to springback.

According to a twenty-sixth aspect of the present invention, an arc-shaped guide portion is provided along the lower portion of the center magnetic leg of the magnetic core at the center of the step portion provided on both sides of the molded body. As a result, the magnetic core can be stably and smoothly incorporated into the molded coil.

According to a twenty-seventh aspect of the present invention, the lower portion of the back portion of the magnetic core is formed along the upper surface of the stepped portion having a C-shape, and the lower portion of the winding is widely covered and the leakage magnetic flux is formed. Can be reduced.

According to a twenty-eighth aspect of the present invention, the upper part of the magnetic leg of the outer leg of the magnetic core is configured to be thick, and the upper part of the winding is covered as widely as possible to reduce the leakage magnetic flux. Reduction can be achieved.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

(Embodiment 1) A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram showing a first embodiment of a choke coil of the present invention, and FIG. 2A is a left side view of a winding for explaining the first embodiment of the present invention. , FIG. 2
(B) is the front view, FIG. 2 (c) is the bottom view, and FIG.
FIG. 3B is a left side view of the magnetic core incorporated state for explaining the first embodiment of the present invention, FIG.
FIG. 4A is a front view of a magnetic core for explaining the first embodiment of the present invention, FIG. 4B is a cross-sectional view taken along line XX ′ of FIG.
FIG. 5A is a top view of a completed product for explaining the first embodiment of the present invention, FIG. 5B is a front view thereof, FIG. 5C is a bottom view thereof, and FIG. It is the same right view.

1 to 5, reference numeral 11 denotes a winding made of a copper wire having an insulating film having a circular cross section, 11a denotes a lead, 12 denotes a surface mounting terminal, 12a denotes a bent portion, 13 denotes a formed body, and 13a denotes a formed body. Reference numeral 13b denotes a flat portion of the molded body 13, 13c denotes a step portion of the molded body 13 supporting the back surface of the magnetic core 14, and 14a denotes a flat back surface of the magnetic core 14. As shown in FIG. 2, the winding 11 is tightly wound by a winding jig without any gap, and then the leading ends of the lead-out leads 11 a at both ends are bent at the positions of the bent portions 12 a, and the foremost portion is used as the surface mounting terminal 12. It is formed below the winding 11 so that it can be used.

Next, as shown in FIG. 3, the surface mounting terminals are made of a high heat resistant plastic insulating resin such as PPS, modified nylon, liquid crystal polymer or the like which can withstand heat during reflow mounting, or a thermosetting insulating resin not melted by heat. A molded body 1 for molding and insulating the entire winding 11 except the lower surface of the portion 12 by molding.
3 to form a molded coil. The magnetic core 14 is assembled from both sides of the molded coil to complete a choke coil.

In manufacturing the winding 11 of the choke coil, the dimensions of the bent portion 12a were set such that the surface-mounting terminal portion 12 was substantially inside the projected area from above the magnetic core 14. The upper surface of the molded body 13 is flattened to make the core 1
4 and the flat portion 1a of the molded body 13 so as to protrude from the top surface of the magnetic core 14.
3b is provided. Further, a step 13c is provided on the molded body 13 so that the flat back portion 14a can be supported when the magnetic core 14 is assembled from both sides, and the step 13c is formed in a C shape so that both ends are lower than the center. In addition, the upper surface is set to be flat and parallel to the direction in which the magnetic core 14 is incorporated.

Further, a guide portion 13h composed of an arc-shaped concave portion matching the lower surface portion of the central magnetic leg 14b of the magnetic core 14 is provided at the center of the upper surface of the step portion 13c, so that the magnetic core 14 can be easily and stably assembled. It is configured to be able to maintain.

The magnetic core 14 used here is shown in FIG.
(A) and (b), the center magnetic leg 14b and the outer leg magnetic leg 1
4c was used, the thickness of the back portion 14a having a small thickness and a large width was used to form a flat back portion 14a. The shape of the flat back portion 14a is set to such a width and thickness that when combined with the molded coil, the empty space above the step portion 13c of the molded body 13 supporting the back portion 14a of the magnetic core 14 is substantially filled. . In addition, the magnetic leg 14c of the outer leg has a thick upper portion, and in this regard, the outer periphery of the winding 11 is also covered with the magnetic core 14 as much as possible, so that leakage magnetic flux is reduced.

According to the above configuration, the surface-mounting terminal portion 12 is formed using the tip of the winding 11 and the winding 1
By molding no. 1, the number of components can be reduced because extra parts such as the molded body case 5, the coil base 8, and the surface mounting terminals 6 which are conventionally used are not used. And the cost can be reduced.

Also, the magnetic cores 14 are incorporated from both sides,
In addition, by providing the surface mounting terminal portion 12 within the projected area of the lower surface portion of the magnetic core 14 and the magnetic core 14, the thick wire can be wound in close contact with no gap, and the surface mounting terminal portion 12 can be wound at the shortest distance from the lead 11 a. As a result, the lower surface of the magnetic core 14 and the empty space within the projected area of the magnetic core 14 can be effectively used, so that the resistance can be reduced and the size can be reduced at the same time. Further, the upper surface of the choke coil is not the winding 11 having irregularities, but the magnetic core 14 or the molded body 13.
Therefore, chucking by suction during automatic mounting becomes easy.

As a result, the object of providing a thin, small, low-loss component that can be automatically mounted and is compatible with surface mounting can be achieved at low cost.

Also, since the protrusion 13a is provided on the molded body 13 in which the magnetic core 14 is incorporated and is protruded from the top surface of the magnetic core 14, the protrusion 13a is used when the choke coil is automatically mounted.
Thus, chucking by suction can be performed, and cracking and chipping of the magnetic core 14 at the time of mounting can be prevented, thereby improving quality.

Further, by making the upper surface of the molded body 13 in which the magnetic core 14 is incorporated flat, it is possible to reduce chuck errors during automatic mounting, thereby improving productivity.

Also, a step 13c for supporting the back surface 14a of the magnetic core 14 is provided on the molded body 13, and the magnetic core 14 is incorporated along the upper surface of the step 13c. , The magnetic core 14 can be assembled from both sides, thereby improving the assemblability and facilitating automation.

In addition, the upper surface of the step portion 13c has a C-shape, and the lower portion of the back surface portion 14a of the magnetic core 14 also has a shape along the step portion 13c. And the leakage magnetic flux can be reduced.

Further, since the shape of the magnetic core 14 incorporated from both sides is a flat magnetic core having a flat back portion 14a, the empty space of the step portion 13c of the molded body 13 can be effectively used, and the occupied volume of the choke coil can be increased. The mounting area on the substrate can be reduced.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to FIGS. FIG.
(A) is a front view of a magnetic core according to a second embodiment of the present invention, in which a magnetic core is assembled, FIG. 6 (b) is a left side view thereof, and FIG.
FIG. 7B is a left side view of a winding for explaining a second embodiment of the present invention, FIG. 7B is a front view thereof, FIG. 7C is a bottom view thereof, and FIG. 8 (b) is a front view, FIG. 8 (c) is a bottom view, and FIG. 9 is FIG. 8 (a) of the molded coil. ), FIG. 10 (a) is a top view of a completed product for explaining the second embodiment of the present invention, FIG. 10 (b) is a front view thereof, and FIG. 10 (c). Is a bottom view, FIG. 10D is a right side view, and FIG. 11 is a second view of the present invention.
FIG. 7 is a board mounting state diagram for describing the embodiment.

6 to 11, reference numeral 12b denotes a processed end portion of the surface mount terminal portion 12, 12c denotes an exposed portion of the surface mount terminal portion 12, and 13d denotes a step of the molded body 13 supporting the magnetic leg 14c of the outer leg of the magnetic core 14. Parts, 13e and 13f are recesses of the molded body 13,
13g denotes an outer shape of the molded body 13, 15 denotes a solder fillet portion, 16 denotes a printed board, and 17 denotes a conductive pattern.

The basic configuration is the same as that of the first embodiment of the present invention. The major difference lies in the device for forming the surface mount terminal portion 12 by processing the tip of the winding 11 and the winding 11.
This is a point that the device 13 is devised to the molded body 13 that holds.

Hereinafter, a detailed description will be given of a device for forming the surface mount terminal portion 12 by processing the tip of the winding 11 with reference to the drawings. After the winding 11 is wound as shown in FIG. 7, a round wire is pressed from a portion of the front end processed portion 12b to the front end with a die and processed into a flat rectangular cross section. The processing of the tip may be performed before the winding of the winding 11. Next, as shown in FIG. 7A, the first fine bending process is performed in the same plane as the lead-out lead portion 11a of the winding wire 11, and this portion is used as a fulcrum as shown in FIG. Line 11
A second bending process is performed in a direction parallel to the winding width direction in which the coil is wound, thereby completing the production of the coil portion.

Next, a description will be given of points in which a device for the molded body 13 for holding the winding 11 is added. As shown in FIGS. 8 and 9, a step 13d for supporting the magnetic leg 14c of the outer leg of the magnetic core 14 is provided, and a concave portion 13e is formed on the inner surface of the molded body 13 into which the central magnetic leg 14b of the magnetic core 14 is inserted. Provided, a concave portion 13f provided on the lower surface of the molded body 13, a terminal exposed portion 12c provided by exposing a side surface of the surface mount terminal portion 12,
Further, as shown in FIG. 10, when the magnetic core 14 is assembled and completed, the dimensions are set so that the outer shape portion 13g of the molded body 13 is larger than the outer shape contour line of the magnetic core 14.

With the above configuration, the following new effects can be obtained in addition to the effects obtained in the first embodiment of the present invention.

First, the shape of the terminal forming portion can be made constant in advance even if the wire diameter of the winding 11 changes largely by processing the tip of the winding 11 to form a terminal. It will be easier. In addition, productivity can be improved because the shape can be set in advance to facilitate bending.

Further, the connection area between the surface mount terminal section 12 and the printed circuit board 16 is increased by processing the tip end of the winding 11 into a square or flat shape to form a terminal, so that connection reliability and stability during reflow mounting are improved. The performance is improved.

Further, by arranging the surface-mounting terminals 12 in parallel with the winding width direction of the windings 11, the movable direction of the mold when the windings 11 are molded with the molding 13 is parallel to the surface-mounting terminals 12. Therefore, the mold can be removed in two directions, and the mold structure design and manufacturing costs can be reduced.

Further, if the first fine bending at the time of forming the terminal is performed in the same plane as the lead 11a of the winding 11, the second final bending can be performed using this portion as a fulcrum. Since the shape of the winding 11 can be prevented from being disturbed by bending stress without using a space in the winding width direction, the dimension in the winding width direction can be reduced.

Further, since the step 13d for supporting the magnetic leg 14c of the outer leg of the magnetic core 14 is provided in the molded body 13, the position of the magnetic leg 14c of the outer leg of the magnetic core 14 is regulated by the step 13d. Can be prevented from shifting in the rotation direction.

Further, by providing a concave portion 13e on the inner surface of the molded body 13 into which the center magnetic leg 14b of the magnetic core 14 is inserted, molding can be performed in a state where a safe distance between the magnetic core 14 and the winding 11 is at least a predetermined value. Therefore, the thickness of the molded body 13 does not become uneven, and the safety of the choke coil is improved.

Further, since the recess 13f is formed in the lower surface of the molded body 13, a space can be secured between the choke coil and the printed board 16 as shown in FIG. It can be used as a space for preventing, preventing inflow of extra solder, venting, etc.

Further, by setting the outer shape of the molded body 13 larger than the outer shape of the magnetic core 14, the outer dimensions are determined by the outer shape portion 13g of the molded body 13 having higher dimensional accuracy than the magnetic core 14, thereby improving the outer shape accuracy of the choke coil. .

By exposing the side surface of the surface mount terminal portion 12, the solder fillet portion 15 when mounted on the printed circuit board 16 as shown in FIG.
Since it can be formed on the side surface, the mounting strength on the substrate is improved.

(Embodiment 3) Next, a third embodiment of the present invention will be described with reference to FIGS. FIG.
2 (a) is a left side view of a winding for explaining a third embodiment of the present invention, FIG. 12 (b) is a front view thereof, and FIG.
13 (c) is a bottom view, FIG. 13 (a) is a left side view of a winding for explaining another example of the third embodiment of the present invention, and FIG. 13 (b) is a front view thereof. 14 (a) is a left side view of a winding for explaining another example in the third embodiment of the present invention, and FIG. 14 (b) is a front view thereof. FIG.
In FIG. 14, the basic configuration is the same as the first embodiment and the second embodiment of the present invention.

Hereinafter, a detailed description will be given with reference to the drawings. The configuration shown in FIG. 12 shows a second embodiment of the present invention.
Is basically the same as that of FIG.
When the leading end of the wire 11 is processed, the lead-out lead portion 11a is pulled out substantially straight downward, and then bent parallel to the winding width direction of the winding 11 to form the surface-mounting terminal portion 12. The configuration shown in FIGS. 13 and 14 is basically the same as the configuration shown in FIG.
The point is that the coil portion is completed without performing a final bending process for forming the terminal portion, and the point portion of the winding 11 is not processed to keep the dimensions of the terminal forming portion constant. In FIGS. 13 and 14, the shape of the coil portion is formed in the state shown in the figure, and then molded with resin. After that, the tip portion is bent and used as the surface mount terminal portion 12.

As described above, according to the configuration of FIG. 12, the lead-out lead portion 11a of the winding 11 is pulled out substantially straight downward, and then bent parallel to the winding width direction of the winding 11 to form the surface-mounting terminal portion 12. This eliminates or further facilitates the initial fine bending process, so that winding winding can be easily automated and equipment costs can be reduced.

In addition, according to the configuration shown in FIGS. 13 and 14, the tip of the winding 11 is bent to form the surface mounting terminal 12 after molding, so that the dimensions of the surface mounting terminal 12 can be changed even when the wire diameter of the winding 11 changes. Therefore, it is not necessary to design the mold in consideration of the above, so that the design of the mold for the mold becomes easy.

(Embodiment 4) Next, a fourth embodiment of the present invention will be described with reference to FIGS. FIG.
5 is a configuration diagram of a choke coil showing a fourth embodiment of the present invention, FIG. 16 is a cross-sectional view of a winding for explaining the fourth embodiment of the present invention, and FIG. It is a block diagram of the choke coil which shows the other example in embodiment of this invention. The drawing is basically the same as the first embodiment of the present invention.
The cross-sectional shape of b is a flat shape such as an ellipse shown in FIG. 15 and an ellipse shown in FIG.
6, the wire is wound using an elliptical wire having a higher space factor than that of the round wire so that the long axes of the wire sections are arranged in the horizontal direction.

In the configuration shown in FIG. 15, since the short-axis side of the cross-sectional shape of the center magnetic leg 14b of the magnetic core 14 is set in the vertical direction, the height of the choke coil can be reduced. Although not shown in the drawing, the height of the choke coil increases when the major axis side is set in the vertical direction, but the area occupied by the board when mounted on a printed board can be reduced.

In FIG. 17, the center magnetic leg 1 of the magnetic core 14 is shown.
Although the sectional shape of 4b is set to be elliptical, the effect is the same as that of FIG.

The cross-sectional shape of the central magnetic leg 14b of the magnetic core 14 is an ellipse and an ellipse in the present embodiment, but it goes without saying that the effect is the same if the shape is a flat type.

As described above, the configuration as shown in FIGS. 15 and 17 further increases the degree of freedom in shape setting, such as making the device thinner and reducing the area occupied by the substrate, thereby facilitating customer needs.

Further, according to the configuration of FIG. 16, the short-axis side of the cross section of the winding 11 is set in the vertical direction, so that the height of the choke coil is further reduced. Although not shown, the height of the choke coil is increased by setting the major axis side to the vertical direction, but the area occupied by the board when mounted on a printed board can be further reduced. Furthermore, since the cross-sectional shape of the winding 11 is set to a shape different from a circle and an elliptical shape having a higher space factor than the circle, the cross-sectional area of the winding 11 increases, the resistance of the choke coil decreases, and In addition to expanding the degree of freedom in setting, it is possible to respond to customer needs for low loss.

Although the cross-sectional shape of the winding 11 is elliptical in FIG. 16, the cross-sectional shape is different from a circle and the space factor is higher than the circle, for example,
It goes without saying that the same effect can be obtained if the shape is an ellipse, rectangle, or square. In practice, the effect can be obtained by using what is called a flat wire or a square wire.

As described above, by using a wire having a cross section having a high space factor of a square wire or a flat wire as the winding 11, the sectional area of the winding 11 can be further increased and the shape of the winding portion can be increased. Can be varied, which further expands the range of response to customer needs, including lower resistance and flexibility in setting the shape.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIGS. FIG.
8 is an exploded perspective view of a choke coil showing a fifth embodiment of the present invention, FIG. 19 is the same perspective view, and FIGS. 20 (a) to (d).
21 is the same top view, front view, bottom view and side view, FIG.
(A)-(c) is the front view, bottom view, and side view of the same molded coil. 18 to 21 are basically the same as the first to third embodiments, and only different points will be described.

An inverted trapezoidal terminal block 18 is integrally provided below the molded body 13 on which the winding 11 is molded.
The upper surface on both sides is a stepped portion 13c, and the upper surface on the front and back surfaces of the terminal block 18 is a stepped portion 13d. The winding 11 is wound almost closely, and both ends are bent at an angle of 30 to 60 degrees so as to protrude outward at the lower part of the winding 11,
The leading end is bent in parallel with the winding width direction of the winding 11 to form the surface mounting terminal 12.

At the time of bending the surface mount terminal portion 12, a notch 19 is formed inside the bent portion 12a to facilitate bending, and a small distance Z from the tapered front and rear wall surfaces of the terminal block 18. It is arranged with. This is to prevent the resin from adhering to the surface mounting terminal portion 12 when molding the molded body 13 to the winding wire 11 and hindering the soldering. Further, the surface mounting terminal portion 12 is located within the outer shape of the step portion 13d, and is configured to be flush with the bottom surface of the terminal block 18.

Further, a concave portion 13f is provided on the bottom surface of the terminal block 18 to secure a space for preventing residual cleaning agent and flux during mounting, preventing excess solder from flowing in, and venting gas.

(Embodiment 6) Next, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 22 (a)
(C) is the front view, bottom view, and side view of the choke coil which shows 6th Embodiment of this invention. The basic configuration is the same as that of the fifth embodiment, and only different points will be described.

The front end and the rear surface of the terminal block 18 are formed by making the tip of the surface mount terminal section 12 drawn out from the terminal blocks 18 at both ends of the winding 11 thinner and bending it toward the terminal block 18 side. Is provided with an engagement groove 20 at one end thereof.
The surface mounting terminal portion 12 can be fixed by inserting the engaging portion 12d into the mounting portion 12 so that even if an external force is applied to the surface mounting terminal portion 12, the surface mounting terminal portion 12 is shifted from a predetermined position and cannot be surface mounted. Is prevented.

[0092]

As described above, according to the present invention, a magnetic core is incorporated from both sides of a molded coil having a surface mounting terminal portion on the bottom surface of a molded body holding a winding, and a lead for drawing out a wire constituting the winding. The surface mount terminal is formed by bending the tip of the part, and this surface mount terminal is located on the lower surface of the magnetic core and almost inside the projected area from above the magnetic core, using extra parts Since there are no components, the number of parts can be reduced, and a simple structure without a connection portion between the surface mount terminal portion and the winding can be achieved to reduce the cost. Also, low resistance and miniaturization can be realized at the same time. Further, since the upper surface of the choke coil is not a winding having irregularities but a magnetic core or a molded body, chucking at the time of automatic mounting becomes easy.

As a result, it is possible to achieve the object of providing a thin, small, low-loss component that can be automatically mounted and is compatible with surface mounting at low cost.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a choke coil of the present invention.

2 (a) is a left side view of a winding for explaining a first embodiment of the present invention, (b) is a front view, and (c) is a bottom view.

FIG. 3 (a) is a left side view of a magnetic core incorporated state for explaining the first embodiment of the present invention.

FIG. 4A is a front view of a magnetic core for explaining a first embodiment of the present invention, and FIG.

5A is a top view of a completed product for explaining the first embodiment of the present invention, FIG. 5B is a front view thereof, FIG. 5C is a bottom view thereof, and FIG.

FIG. 6A is a front view of a magnetic core according to a second embodiment of the present invention, in which the magnetic core is assembled. FIG.

FIG. 7A is a left side view of a winding for explaining a second embodiment of the present invention, FIG. 7B is a front view, and FIG.

8A is a left side view of a molded coil for explaining a second embodiment of the present invention, FIG. 8B is a front view thereof, and FIG.

FIG. 9 is a sectional view taken along the line YY ′ of a molded coil for describing a second embodiment of the present invention.

10A is a top view of a completed product for explaining a second embodiment of the present invention, FIG. 10B is a front view, FIG. 10C is a bottom view, and FIG.

FIG. 11 is a diagram showing a state of mounting on a substrate for explaining a second embodiment of the present invention;

12 (a) is a left side view of a winding for explaining a third embodiment of the present invention, (b) is a front view, and (c) is a bottom view.

FIG. 13A is a left side view of a winding showing another example according to the third embodiment of the present invention. FIG.

14A is a left side view of a winding showing another example of the third embodiment of the present invention, and FIG.

FIG. 15 is a configuration diagram of a choke coil showing a fourth embodiment of the present invention.

FIG. 16 is a sectional view of a winding for explaining a fourth embodiment of the present invention;

FIG. 17 is a configuration diagram of a choke coil showing another example according to the fourth embodiment of the present invention.

FIG. 18 is an exploded perspective view of a choke coil according to a fifth embodiment of the present invention.

FIG. 19 is a perspective view of the same.

20A is a top view thereof, FIG. 20B is a front view thereof, FIG. 20C is a bottom view thereof, and FIG.

21A is a front view of the molded coil, FIG. 21B is a bottom view thereof, and FIG.

FIG. 22 (a) is a front view of a choke coil according to a sixth embodiment of the present invention, (b) is a bottom view thereof, and (c) is a side view thereof.

FIG. 23 is an external view showing a conventional choke coil.

FIG. 24 is a configuration diagram showing another typical example of a conventional choke coil.

FIG. 25 is a configuration diagram showing another typical example of a conventional choke coil.

FIG. 26 is a top view illustrating a conventional choke coil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Winding 11a Lead-out lead part 12 Surface mounting terminal part 12a Bend part 12b Tip processing part 12c Terminal exposure part 12d Engagement part 13 Molded body 13a Projection part 13b Flat part 13c Step part 13d Step part 13e Recess 13f Recess 13g Outer part 13h Guide portion 14 Magnetic core 14a Back portion 14b Central magnetic leg portion 14c Magnetic leg of outer leg 15 Solder fillet portion 16 Printed circuit board 17 Conductive pattern 18 Terminal block 19 Notch 20 Engagement groove

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01F 37/00 H05K 1/18 H H01F 15/02 FL // H05K 1/18 15/10 H (72) Inventor Yu Yoshihara Matsushita Electric Industrial Co., Ltd. (72) Inventor Kiyoshi Takagi 1006 Kadoma Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (28)

[Claims] 1. A surface mount terminal in which magnetic cores are incorporated from both sides of a molded coil having a surface mount terminal portion on the bottom surface of a molded body holding a winding, and a leading end of a lead wire lead portion of a wire constituting the winding is bent. A choke coil having a surface-mounting terminal portion located on the lower surface of the magnetic core and positioned substantially inside a projection contact from above the magnetic core. 2. The choke coil according to claim 1, wherein an upper surface portion of the molded body into which the magnetic core is incorporated projects from a top surface of the magnetic core. 3. The choke coil according to claim 2, wherein the upper surface of the molded body incorporating the magnetic core is flat. 4. The choke according to claim 1, wherein a stepped portion for supporting at least a part of the back surface of the magnetic core is provided on the molded body, and the upper surface of the stepped portion is shaped like a letter C and parallel to the direction in which the core is incorporated. coil. 5. The choke coil according to claim 1, wherein the magnetic core incorporated from both sides is a flat magnetic core having a thin back surface. 6. The choke coil according to claim 1, wherein a tip portion of the winding is processed into a surface mounting terminal portion. 7. The choke coil according to claim 1, wherein a tip portion of the winding is processed into a square or flat shape to form a surface mounting terminal portion. 8. The choke coil according to claim 1, wherein the surface-mounting terminal portions are arranged in parallel with a winding width direction of the winding. 9. The choke coil according to claim 1, wherein the first fine bending at the time of forming the terminal is performed in the same plane as the lead portion of the winding. 10. The choke coil according to claim 1, wherein a stepped portion for supporting the magnetic leg of the outer leg of the magnetic core is provided on the molded body. 11. The choke coil according to claim 1, wherein a recess is provided on an inner surface of the molded body into which the center magnetic leg of the magnetic core is inserted. 12. The choke coil according to claim 1, wherein a recess is formed in a lower surface of the molded body. 13. The choke coil according to claim 1, wherein the outer shape of the molded body is set larger than the outer shape of the magnetic core. 14. The choke coil according to claim 1, wherein a side surface of the surface mount terminal portion is exposed. 15. The choke coil according to claim 1, wherein the lead portion of the winding is drawn out substantially straight downward, and then bent in parallel with the winding width direction of the winding to form a surface mount terminal portion. 16. The choke coil according to claim 1, wherein a tip is bent after molding to form a surface mounting terminal portion. 17. The choke coil according to claim 1, wherein the cross-sectional shape of the center magnetic leg of the flat core is a flat shape such as an ellipse or an ellipse. 18. The choke coil according to claim 1, wherein a wire having a cross section having a high space factor such as a square wire or a flat wire is used as the winding. 19. The choke coil according to claim 1, wherein a copper wire having an insulating film having a circular cross section is used as the winding. 20. The choke coil according to claim 1, wherein an inverted trapezoidal terminal block is integrally provided at a lower portion of the molded body, and surface mount terminal portions are disposed on tapered surfaces on the front and back surfaces of the terminal block. 21. Pull out both ends of the winding at an angle of 30 to 60 degrees so as to protrude outward at the lower part of the winding, and draw out the surface mount terminal portions on the front and back tapered surfaces of the terminal block of the molded body. The choke coil according to claim 20, wherein the choke coil is configured. 22. The choke coil according to claim 20, wherein the surface-mounted terminal portions at both ends of the winding are located slightly apart from the tapered surfaces on the front and back surfaces of the terminal block of the molded body. 23. The choke coil according to claim 22, wherein the tip of the surface mount terminal portion is bent to engage with the terminal block of the molded body. 24. The terminal according to claim 22, wherein the tip of the surface-mounting terminal portion is thinned and bent to form an engaging portion, and the engaging portion is engaged with an engaging groove provided in a tapered surface on the front and back surfaces of the terminal block of the molded body. Choke coil. 25. The choke coil according to claim 1, wherein a notch is provided inside the bent portion to form a surface mount terminal portion by bending both ends of the winding. 26. The choke coil according to claim 4, wherein an arc-shaped guide portion is provided along the lower portion of the center magnetic leg of the magnetic core at the center of the step portion provided on both sides of the molded body. 27. The choke coil according to claim 4, wherein a lower portion of the back surface of the magnetic core is formed along the upper surface of the stepped portion having a C shape. 28. The choke coil according to claim 10, wherein the upper part of the magnetic leg of the outer leg of the magnetic core is configured to be thick.