JPH09306744A - Chip inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate mounting by a structure including a core composed of a winding core of a circular cross section with rectangular brims formed on both ends thereof and with outer electrode conductive films formed on the brims, a winding connected with the outer electrode conductive films, and an enclosure member having portions corresponding to the corners of the brim which are protruding toward the corners and having a flat surface corresponding to each side of the brim. SOLUTION: A magnetic core 1 includes a winding core 1a of a circular cross section and rectangular brims 1b, 1b provided on both ends thereof. On the outer lateral surface and peripheral surface of the brims 1b, 1b having a V-shaped groove 2 formed in each side thereof, outer electrode conductive films (films) 3, 3 are formed. An insulated wire is wound on the winding core 1a of the magnetic core 1, thus mounting a winding 4. Terminals 5, 5 are inserted in the V-shaped grooves 2, 2 and connected with the films 3, 3. On the surface of an enclosure member 6 of synthetic resin applied on the entire outer peripheral surface of the winding 4, portions inner than the peripheral surfaces of the brims 1b, 1b and corresponding to the corners of the brims 1b, 1b protrude outward from inscribed circles of the brims 1b, 1b, and a surface 6a of the enclosure member 6 corresponding to each side of the brims 1b, 1b is flattened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip inductor mounted on a printed board.

[0002]

2. Description of the Related Art Conventionally, this type of chip-shaped inductor is
For example, as shown in FIG. 8, an end of a winding b wound around a winding core of a drum-shaped core a is connected to an external electrode c composed of a lead frame fixed to the outer surface of a circular brim of the core a. ,
The drum-shaped core a and the external electrode c are covered with a rectangular parallelepiped exterior resin d, and the L-shaped portion at the tip of the external electrode c is exposed on both side surfaces and the lower surface of the exterior resin d. .

[0003]

The conventional chip-shaped inductor described above can be easily and surely mounted because it can be surely sucked and held by the suction nozzle when it is mounted on a printed circuit board by an automatic mounting machine. However, since a large amount of exterior resin is required and an external electrode composed of a lead frame is used, the manufacturing cost becomes high and the size becomes large. The present invention provides a chip-shaped inductor that solves the above problems.

[0004]

In order to solve the above-mentioned problems, according to the present invention, as described in claims 1 and 2, a square flange is formed at both ends of a winding core having a circular cross section, and the flange is externally provided. A core on which a conductive coating for electrodes is formed, a winding wound around the core of the core and having an end connected to the conductive coating for external electrodes, and the entire circumference of the winding only on the outer peripheral surface of the winding. At least one side of the square-shaped collar that is attached to the outer surface of the square-shaped collar and has a surface corresponding to each side of the square-shaped flange that is flattened so that a portion of the surface corresponding to the corner of the collar protrudes toward the corner. Corresponding to the outer peripheral surface of the winding, and the outer surface of the outer surface is planarized. Further, as described in claims 3 and 4, a core in which a conductive cap for an external electrode having a circular cross section and a rectangular shape at both ends is fitted, and a terminal wound around the core is connected to the conductive cap for the external electrode. And a portion of the surface corresponding to a corner portion of the conductive cap, which is adhered over the entire circumference only on the outer peripheral surface of the winding wire and projects toward the corner portion. An exterior material whose surface corresponding to a side is planarized or an exterior material whose surface is planarized by being applied only on the outer peripheral surface of the winding corresponding to at least one side of the rectangular external electrode conductive cap. It is characterized by being formed.

According to the first to fourth aspects of the present invention, in the chip-shaped inductor of the present invention, the suction nozzle of the automatic mounting machine is attached to the exterior material which is attached only on the outer peripheral surface of the winding and whose surface is flattened. When applied, it is easily adsorbed and transferred onto the printed circuit board. The conductive coating for external electrodes attached to the square flanges on both ends of the core or the square conductive caps for external electrodes fitted on both ends of the core with a circular cross section are connected to the conductive parts of the printed circuit board by soldering. The inventive chip-shaped inductor is mounted on a printed circuit board.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of the chip-shaped inductor of the present invention.

In the figure, reference numeral 1 is a magnetic core made of, for example, ferrite, which is composed of a winding core 1a having a circular cross section and square flanges 1b, 1b provided at both ends thereof and having a side of, for example, 0.8 mm. For example, silver, silver-platinum or copper and lead deposited on the outer and peripheral surfaces of the collars 1b, 1b having a V-shaped groove 2 having a depth of 0.06 mm by plating or dipping / baking. -The conductive coatings 3 and 3 for external electrodes made of tin or the like are formed. A winding 4 having a diameter of, for example, 50 to 100 μm and a coating material of polyurethane, polyamideimide, or the like is wound around the winding core 1a of the magnetic core 1 to wind the winding 4, and the terminals 5 and 5 of the winding are wound around the collar 1b. V-shaped groove 2,
2 is inserted into the external electrode conductive coatings 3 and 3 and joined by welding, thermocompression bonding or ultrasonic vibration. In this thermocompression bonding, the heated head is pressed against the terminal 5 of the insulation-coated electric wire so that the terminal 5 is deformed and flattened and diffusion-bonded to the conductive coating 3. In ultrasonic vibration, the insulating coating of the terminal 5 is removed by the vibration of the head, and the cleaned copper wire and the conductive coating 3 are joined by pressing the heated head. Since the cross section of the winding core 1a is formed in a circular shape, the insulation-coated electric wire can be wound in close contact with the surface of the winding core 1a, and the variation in the inductance value is greater than that in the case where the winding core has a rectangular cross section. Is less likely to damage the insulation coating of the wire. Reference numeral 6 denotes an exterior material made of an insulating material such as an epoxy synthetic resin (which may contain a filler), which is attached to the entire outer peripheral surface of the winding wire 4 by potting, for example. Inner than the peripheral surfaces of the collars 1b, 1b and the collars 1b, 1b
The surface 6a of the exterior material 6 corresponding to each side of the collars 1b, 1b is planarized by projecting outwardly from the inscribed circles of the collars 1b, 1b.

This inductor uses the magnetic core 1, but in the case of a low-inductance inductor, a core made of an insulator such as alumina may be used, and the exterior material 6 may be used.
May be coated not on the entire outer peripheral surface of the winding wire 4 but on the intermediate portion of the winding wire 4 except for both ends in the axial direction, as shown in FIG. .

The chip-shaped inductor is easily transferred and arranged on the printed circuit board by applying a suction nozzle of an automatic mounting machine to the flattened surface 6a of the exterior material 6 to adsorb the chip-shaped inductor to the outside formed on the collar 1b. The electrode conductive coatings 3, 3 are mounted on the printed board by soldering to the conductive parts of the printed board. In this chip-shaped inductor, it is not necessary to consider the mounting surface when arranging the chip-shaped inductor on the printed board, and since the collar 1b of the magnetic core 1 is formed in a square shape, it rolls like a circular collar. Never.

The conductive coatings 3 and 3 for the external electrode of the magnetic core 1 or the insulative core are, as shown in FIG. 3A, by changing the depth of dipping or plating the collars 1b and 1b of the core. It may be attached to a part of the peripheral surface of the width of 1b, 1b, or may be attached up to the inner surface of the collars 1b, 1b as shown in FIG. 3 (B).

The magnetic core 1 of the chip-shaped inductor
Grooves 1b, 1b of the groove 2 into which the terminal 5 of the winding 4 is inserted,
Although the groove 2 is formed, the grooves 2 and 2 may not be formed,
Further, as shown in FIGS. 4A and 4B, the terminal 5 of the winding 4 is inclined with respect to the thickness direction of the collar 1b, or
It may be connected to the outer electrode conductive coatings 3 and 3 in a state of being bent along the outer surfaces of b and 1b. Also in this case, as in the case shown in FIG. 1, the terminals 5 and 5 of the winding wire 4 are flatly deformed and joined to the conductive coatings 3 and 3 for external electrodes of the collar 1b by welding, thermocompression bonding or ultrasonic vibration. .

FIG. 5 shows another chip-shaped inductor of the present invention.

In this inductor, the exterior material 6 is attached to the outer peripheral surface of the winding wire 4 corresponding to one side of the peripheral surface of the rectangular collars 1b and 1b. The surface 6a of the exterior material 6 has a collar 1
The inner surfaces of the peripheral surfaces b and 1b are planarized. Other structures are not different from those shown in FIG. This exterior material 6
Can also be similarly applied to the outer peripheral surface of the winding 4 corresponding to the other one side or two sides of the peripheral surfaces of the square collars 1b, 1b.

The groove 2 formed on the collar 1b is formed on each side of the collar 1b and 1b in the inductor shown in FIG. 1 and on two opposite sides in the inductor shown in FIG. 5, but the groove 1b is necessary. It can be set to an appropriate number according to. When the groove 1b is formed on all four sides, the terminals 5 and 5 of the winding 4 can be inserted and joined to any of the four grooves 1b in order to obtain a desired inductance value.

FIG. 6 shows another chip-shaped inductor according to the present invention.

Magnetic or insulating core 1 _{1 of} this inductor
It has been circular in cross section, to which the winding 4 wound insulated wire is wound, rectangular external electrode on the opposite ends of the core 1 ₁ so as to press the terminal 5 of the winding 4 The conductive cap 7 is fitted and fixed. The outer peripheral surface of the winding 4 is covered with an exterior material 6 made of, for example, a synthetic resin. In the same manner as shown in FIG. 1, the exterior material 6 has a surface 6a which is inside the outer peripheral surface of the external electrode conductive caps 7, 7 and whose portions corresponding to the corners of the conductive caps 7, 7 are electrically conductive. Surfaces 6a, which project outward from the inscribed circles of the caps 7 and 7 and correspond to the respective sides of the rectangular conductive caps 7 and 7, are formed flat.

FIG. 7 shows a chip-shaped inductor which is a modification of the one shown in FIG.

In this inductor, a rectangular outer electrode conductive cap 7 is fitted to both ends of a magnetic or insulating core 1 ₁ having a circular cross section, and then wound around the core 1 ₁ . Both ends 5 and 5 of the wound winding 4 are the caps 7 and 7.
Connected to the outer peripheral surface of the above by the above-mentioned joining,
Other configurations are the same as those shown in FIG.

In the inductor shown in FIGS. 6 and 7,
Similar to the inductor shown in FIG. 2, the jacket material 6 may be attached over the entire circumference on the outer peripheral surface of the intermediate portion of the winding 4 excluding both ends in the axial direction. Thus, it can be attached on the outer peripheral surface of the winding wire 4 corresponding to at least one side of the peripheral surface of the rectangular outer electrode conductive cap 7.
In the chip-shaped inductors shown in FIGS. 1, 2, 5, 6 and 7, the surface of the exterior material 6 may be planarized so as not to interfere with suction by the suction nozzle of the automatic mounting machine,
That is, the cross-sectional shape may be such that it is not concentric with the winding core 1a and that the unevenness due to the winding of the insulating coated electric wire is reduced in the axial direction of the winding core 1a. Further, the exterior material 6 of the inductor shown in the same drawing is either the collar 1b or the conductive cap 7
Since it is formed on the inner side of the peripheral surface, it is preferable in terms of mountability, but it may be formed on the outer side or flush. Further, for example, an epoxy resin containing magnetic powder such as ferrite powder and red iron oxide powder may be used as the exterior material 6.
When this material is used, the inductance value is improved, the number of turns can be reduced by the increased amount, and the shield effect is produced. Further, the collar 1 of the magnetic core 1 shown in FIGS.
Although b is formed in a square shape with rounded corners, it may be rectangular or polygonal as long as it is square, and may or may not have rounded corners of 0.1 mm to 0.3 mm. . Further, the conductive cap 7 for external electrode of the chip-shaped inductor shown in FIGS. 6 and 7 is also formed in a square shape, but may be a polygonal shape if it is a square shape.

[0021]

Industrial Applicability The present invention can easily and surely suck and transfer by a suction nozzle when mounting on a printed circuit board by an automatic mounting machine, and can be carried out like a drum core having a circular brim. Since it does not roll on the printed circuit board, it is easy to mount. Also, unlike the above-mentioned conventional example, a large amount of exterior resin is not required and it is not necessary to use an external electrode composed of a lead frame, so that it can be manufactured inexpensively and in a small size. It has the effect of being able to.

[Brief description of drawings]

1A and 1B are a perspective view and a sectional view of an example of a chip-shaped inductor of the present invention.

2A and 2B are side views of modified examples of what is shown in FIG.

3A and 3B are cross-sectional views of a magnetic core for a chip-shaped inductor according to the present invention having a conductive coating film for external electrodes, which is different from that in FIG.

4A and 4B are plan views showing an example in which the connection state of the winding terminal to the conductive coating for the external electrode is different from that in FIG.

5A and 5B are a perspective view and a sectional view of another example of the chip-shaped inductor of the present invention.

6A and 6B are a longitudinal sectional view and a lateral sectional view of still another example of the chip-shaped inductor of the present invention.

7A and 7B are a longitudinal sectional view and a lateral sectional view showing a modified example of the chip-shaped inductor shown in FIG.

8A and 8B are a perspective view and a sectional view of a conventional chip-shaped inductor.

[Explanation of symbols]

1 Magnetic core having a collar 1a Core 1b Square flange 1 ₁ Core having a circular cross section 3 Conductive coating for external electrode 4 Winding 5 Terminal 6 Exterior material 6a Surface 7 Conductive cap for external electrode

Claims (4)

[Claims] 1. A core in which a square flange is formed at both ends of a core having a circular cross section, and a conductive coating for an external electrode is formed on the flange, and a core wound around the core of the core has a terminal for conducting the external electrode. The winding connected to the coating, and a portion of the surface that is attached only on the outer peripheral surface of the winding and covers the entire circumference thereof and that corresponds to the corner portion of the flange projects toward the corner portion. A chip-shaped inductor, characterized in that the surface of a portion corresponding to a side is made flat by an exterior material. 2. A core having rectangular flanges formed at both ends of a core having a circular cross section, and a conductive coating for an external electrode formed on the flange, and a core wound around the core of the core and having terminals for the external electrode conductive material. A chip shape characterized by comprising a winding wire connected to the coating and an exterior material which is adhered only on the outer peripheral surface of the winding wire corresponding to at least one side of the square brim and the surface of which is planarized. Inductor. 3. A core in which a conductive cap for an external electrode having a circular cross section and a square shape at both ends is fitted, a winding wound around the core and having an end connected to the conductive cap for the external electrode, and the winding. The entire surface of the conductive cap is attached only on the outer peripheral surface thereof, and the portions of the surface corresponding to the corners of the conductive cap project toward the corners, and the surface corresponding to each side of the rectangular conductive cap is flattened. A chip-shaped inductor, comprising: 4. A core having a circular cross section and a rectangular outer electrode conductive cap fitted to both ends, a winding wound around the core and having an end connected to the outer electrode conductive cap, and a rectangular wire. A chip-shaped inductor, comprising: an exterior material that is attached only on the outer peripheral surface of the winding corresponding to at least one side of the external electrode conductive cap and has a planarized surface.