JPH0888123A - Chip type inductor and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide a chip type inductor and manufacture thereof having excellent mass productivity and stable and excellent impedance characteristics. CONSTITUTION: A bar body 8 is formed from extrusion molding step using the first primary extrusion molding machine 7 of a kneading material 6 comprising a magnetic body material particles B and coupling material S and after winding a conductor wire 10 around the bar body 8 in a coil shape, said bar body 8 is wound up with the conduction wire 10 using the secondary extrusion molding machine 11 of another kneading material 12 so as to form an exterior body and then the bar body 8 and the exterior body, after baking step are cut off in a specific length to form a plurality of chip type inductor main body 13. Next, the gaps (not shown in figure) formed between the coil conductor wire 10 and the magnetic body is filled up with a specific paste and then external electrodes connecting to the ends of the exposed conductor wire 10 are formed on both end faces of the chip type inductor main body 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type inductor using a fired magnetic core and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a kneaded material obtained by kneading a raw material powder of a magnetic material and a binder is pressed to form a rectangular parallelepiped or a cylindrical body and fired to form a magnetic rod, and a conductor is wound around the magnetic rod. There is known a method for manufacturing a chip-type inductor in which a coil is mounted, the coil is covered with a kneading material of a magnetic material powder and a binder, and then the coil is fired.

[0003]

In the chip-type inductor manufactured as described above, since the coil is covered with the magnetic material, a circular magnetic circuit is formed surrounding the coil, and therefore the inductance value is increased. And the magnetic field leaking out of the magnetic material is almost eliminated. Therefore, there is an advantage that the characteristics of the inductor are not affected even if the chip inductors are arranged close to each other, and the mounting density of components on the circuit board or the like can be increased.

However, this inductor manufacturing method lacks mass productivity and contracts during firing of the kneaded material of the jacket, so that the magnetic rod inside the coil is exposed to the conductor wire of the coil and / or the gap between the conductor wire and the conductor wire. Pressure is applied,
There is a problem that the magnetic characteristics are adversely affected and the impedance characteristics are deteriorated.

An object of the present invention is to provide a chip-type inductor which is free from such conventional problems, is excellent in mass productivity, has excellent impedance characteristics, and is stable, and a manufacturing method thereof.

[0006]

In order to achieve the above object, a chip-type inductor according to claim 1 is a coil-shaped conductor wire, a magnetic core formed by firing and having the coil-shaped conductor wire embedded therein, and the magnetic core. A gap formed between the coil-shaped conductor and the magnetic core, the external electrode being formed of a conductive coating film attached to both end faces of the core and exposed at both end faces of the coil-shaped conductor. Both ends of the are filled with an inorganic filler. The method for manufacturing a chip inductor according to claim 2, wherein a core is formed by extrusion molding of a kneading material obtained by kneading the magnetic material powder and the binder, and the conducting wire is wound around the core, A kneaded material is extruded to surround a core formed by winding a conductive wire into a coil to form a jacket, and then the core and the jacket are fired and then cut into a predetermined length to form a coil. A plurality of chip-shaped inductor main bodies in which the coil-shaped conductors are embedded in a magnetic core, and both ends of the magnetic body formed between the coil-shaped conductors of the chip-shaped inductor main body and the magnetic core from both end surfaces of the magnetic core. The gap between the parts was filled with a paste composed of an inorganic filler and a solvent, and then the conductive paste was applied to both end faces of the magnetic core and baked to form an external electrode connected to the exposed end of the conductor wire. It is characterized by The mixing ratio of the magnetic material powder and the binder of the core is selected to be smaller than or equal to the mixing ratio of the magnetic material powder and the binder of the outer casing, or the magnetic material of the core is selected. The particle size of the powder is smaller than or the same as the particle size of the magnetic material powder of the outer jacket, and the shrinkage rate of the core during firing is larger than or the same as the shrinkage rate of the outer shell.

[0007]

[Function] A step of forming a winding core by kneading the magnetic material powder and the binder, and extruding the kneading material, a step of winding a conducting wire into a coil around the winding core, and a conducting wire by extruding the kneading material A step of forming a jacket by surrounding the wound core around the core, a step of firing the core and the jacket, and a step of cutting into a predetermined length to form a plurality of chip-shaped inductor bodies. By doing so, a plurality of chip-type inductor bodies can be manufactured at the same time. The mixing ratio of the magnetic material powder and the binder of the winding core is selected to be smaller than or the same as the mixing ratio of the magnetic material powder and the binder of the outer casing, or
The particle size of the magnetic material powder of the core is set to be smaller than or the same as the particle size of the magnetic material powder of the jacket, and the shrinkage rate at the time of firing of the core is smaller than that of the jacket. When the values are made large or the same, the stress due to the contraction during the firing of the jacket does not act on the conductor wire and / or the winding core through the gap between the wound conductor wire and the conductor wire, so that the impedance characteristic of the inductor is not impaired.

The mixing ratio of the magnetic material powder and the binder of the core is selected to be smaller than the mixing ratio of the magnetic material powder and the binder of the outer casing, or the magnetic material powder of the core is selected. If the particle size of the core is smaller than the particle size of the magnetic material powder of the outer jacket, the shrinkage rate of the winding core during firing is larger than that of the outer jacket, so that A gap is formed between the coiled conductor and the magnetic body. Further, the mixing ratio of the magnetic material raw material powder and the binder of the winding core is selected to be the same as the mixing ratio of the magnetic material raw material powder and the binding material of the outer casing, or the magnetic material raw material powder of the winding core is selected. Even if the particle size of the core material is made the same as the particle diameter of the magnetic material powder of the outer jacket, and the shrinkage rate during firing of the winding core is the same as the outer shell shrinkage rate, When the coiled conductor is not deformed during firing, a gap is formed between the coiled conductor and the magnetic material inside the coiled conductor. When the coiled wire is deformed, a gap is formed between the outer cover and the magnetic body of the winding core. In addition, after winding a conductive wire around the winding core in a coil shape and then extruding the kneaded material to surround the winding core around which the conductive wire is wound into a coil to form an outer covering, Regardless of the contraction ratio of the winding core, a gap may be formed between the conductive wire wound in a coil shape and the conductive wire without coming into contact with the winding core until it comes into contact with the winding core. When these gaps are created, the conductive paste is applied to both end faces of the magnetic body while leaving the gap and baked to form the external electrodes. 1 of the end of the conductor wire
Winding or several windings may be short circuited. Therefore,
Impedance characteristics tend to vary. Therefore, before forming the external electrodes, a paste composed of an inorganic filler such as glass or calcined magnetic material powder and a solvent is filled in these gaps at both ends of the magnetic material to form the external electrodes. If the conductive material of the external electrode does not enter the gap, the one or several turns of the end of the coil-shaped conductor will not be short-circuited by the conductive material of the external electrode, and the impedance characteristics will always be constant. Become.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a chip inductor according to the present invention. In the figure, 1 is a coil-shaped conductor wire around which a conductor wire made of a silver wire having a diameter of 20 to 100 μm is wound, and 2 is a rectangular parallelepiped shape (for example, L: 1. 0 to 10.0 mm, W:
0.5 to 10.0 mm, H: 0.5 to 10.0 mm,
(e: 0 to 4.0 mm) magnetic bodies 3, 3 cover both end surfaces of the magnetic body 2 and the outer peripheral surface end portions connected to the both, and both of the coil-shaped conductors 1 exposed on the both end surfaces. Terminal 4,
4 is an external electrode connected to.

The magnetic body 2 is composed of a magnetic body inside which is a winding core of the coil-shaped conducting wire 1 and a magnetic body as an outer covering that covers the coil-shaped conducting wire 1. The magnetic body inside is composed of a composition. Is, for example, iron / nickel / zinc / copper and a magnetic material powder having a particle size of 0.7 μm and a binder of glycerin / cellulose. The mixing ratio of the magnetic material powder and the binder is 100. A kneaded material of No. 8 is formed into a cylindrical shape and fired, and has a magnetic permeability of, for example, 100, a shrinkage rate at firing of, for example, 1.3, and Of a magnetic material powder having the same composition and particle size as the magnetic material and the same binder, and the magnetic material raw material powder and the binder are mixed in a mixing ratio of 100: 6. The contraction rate is, for example, 1.24. With these shrinkage rates, at the time of molding, H and W were each 4.0 mm, and the winding core inside the coil-shaped conductor 1 was φ.
Although it was 2.6 mm, H and W were 3.2 mm each at the time of firing, the magnetic body of the core was φ2 mm, and the gap 21 of 1 mm between the coil-shaped conductor 1 and the magnetic body of the core 21 was obtained. Was formed. Reference numeral 22 denotes an inorganic filler 22 filled in the gap 21, such as glass powder or calcined magnetic material raw material powder. Even when the shrinkage rate of the winding core and the shrinkage rate of the outer casing at the time of firing are the same, when the coil-shaped conductor wire 1 is not deformed or is slightly deformed, a gap similar to the above is formed. Is filled.

According to the above construction, the gap 2 of the filler 22 is formed.
By filling 1 of the coiled conductor 1, one or several turns of the end of the coil-shaped conductor 1 is prevented from being short-circuited by the conductive material of the external electrode.

Further, in any case where the coil-shaped conductor 1 is deformed or not deformed due to contraction of the jacket, the kneading material of the jacket is formed into a coil-shaped conductor and a conductor during extrusion molding. A gap may be formed without coming into contact with the winding core from the space between them, and at this time also, the gap 21a is formed in the gap shown in FIG.
The filling material 22a is filled as shown in (indicates that the contraction rate is the same and the coiled conductor is deformed). As a result, approximately one turn at the end of the coil-shaped conductive wire 1 will cause the external electrode 3
The conductive material prevents the short circuit.

As in the external electrodes of the above embodiment, when the silver paste is baked and nickel plating and solder plating are applied to improve the solderability, cleaning and drying are not required. When it is insufficient, there is also an effect that the plating liquid and the water are not left in the gap to corrode the coil-shaped conductor 1.

Next, a method of manufacturing the chip inductor according to the present invention shown in FIGS. 1 and 2 will be described. FIG.
As shown in, for example, the binder S and the magnetic material powder B having the above-described mixing ratio are kneaded by the kneader 5 to homogenize the magnetic material powder and the binder, and the kneaded material 6 is kneaded. 1
The rod body 8 as a desired winding core having a diameter of, for example, 0.5 to 10 mm, which is molded from the outlet of the primary extrusion molding machine 7, is supplied to the secondary extrusion molding machine 7 at a speed of, for example, 30 m / sec. Extrude with. This rod body 8 is dried by, for example, a dryer (not shown), and then the conductor wire 10 is wound by a winding machine 9, and the rod body 8 on which the conductor wire 10 is wound is sent to a secondary extrusion molding machine 11. To do. In the secondary extrusion molding machine 11, in the kneading machine 5, the kneading material 6 pressurized and supplied to the primary extrusion molding machine 7 is mixed with the kneading material by increasing the mixing ratio of the magnetic material powder and the binder. 6
Since the kneading material 12 having a shrinkage ratio smaller than that of the kneading material is supplied under pressure, the conductor 10 wound around the rod body 8 is covered with the kneading material 12 by the molding machine 11 to form the jacket. After this, cut according to the size of the firing furnace or the shape of the setter laid below, and 600 to 1000 ° C., for example 900 ° C.
Bake at, and cut with a cutter according to the size of each inductor. Each of the cut inductor bodies 13 is barrel-polished with barrel powder and water to have rounded corners. Next, from both end surfaces of the inductor body 13, a gap was formed between the ends of the magnetic body 2 formed between the coil-shaped conductor 1 and the internal magnetic body, or between the magnetic body of the jacket and the internal magnetic body. The gap is vacuum impregnated with a paste composed of a filler such as glass and calcined magnetic material raw material powder and a solvent (a vacuum is applied while being immersed in the filler, and the gap is impregnated with the filler). After that, a silver paste composed of silver powder and a solvent is applied to both end surfaces of the inductor body 13 and the end portions of the outer peripheral surface continuous with the same, and baked to form the external electrodes 3. This time,
Coil-shaped conductor 1 exposed on both end surfaces of the inductor body 13
The terminals 4 and 4 and the external electrode 3 are connected. External electrode 3
The silver layer of is plated with nickel and solder.

In this embodiment, since the shrinkage rate of the magnetic body inside the coil-shaped conductor 1 during firing is made larger than the shrinkage rate of the magnetic body which is the jacket, the shrinkage of the magnetic body of the jacket body during firing. The stress due to is applied to the coil-shaped conducting wire 1 and even if it is deformed, the stress is not applied to the internal magnetic body, so that the impedance characteristic of the inductor does not deteriorate.

When the coil-shaped conductor 1 is not deformed by the stress from the outer cover during firing even when the core material and the outer cover have the same mixing ratio of the magnetic material powder and the binder and the same shrinkage ratio. Creates a gap between the coil-shaped conductor 1 and the magnetic substance inside the coil-shaped conductor 1, so that the external electrode 3 is formed after filling the gap with paste as described above. Also in this case, the impedance characteristic of the inductor does not deteriorate.

The particle size of the magnetic material powder of the winding core is, for example, 0.7 μm, and the particle size of the magnetic material powder of the envelope is, for example, coarser than 0.7 μm. Also in this case, the shrinkage factor during firing of the winding core can be made larger than the shrinkage factor of the jacket, and a gap is created between the coil-shaped conductor 1 and the magnetic body inside, so that the gap is filled with the filler. Is filled.

[0018]

Since the present invention is constructed as described above,
It has the advantages of excellent mass productivity, excellent impedance characteristics, and a stable chip inductor.

[Brief description of drawings]

1A and 1B are a perspective view and a partially cut side view of a chip inductor according to the present invention.

FIG. 2 is a cross-sectional view of another example of the chip inductor according to the present invention.

FIG. 3 is an explanatory diagram of an apparatus used for carrying out a method for manufacturing a chip inductor according to the present invention.

[Explanation of symbols]

1 Coiled Conductor Wire 2 Magnetic Material 3 External Electrode 5 Kneading Machine 6, 12 Kneading Material 7
Primary extrusion molding machine 8 Rod 9 Winding machine 10 Conductive wire 11 Secondary extrusion molding machine 13 Inductor body 21a, 21 Gap 22, 22a Filler

Claims (4)

[Claims] 1. A coil-shaped conductive wire, a magnetic core formed by firing and having the coil-shaped conductive wire embedded therein, and connected to both ends of the coil-shaped conductive wire which are attached to both ends of the magnetic core and exposed at both ends. And an external electrode made of a conductive coating,
A chip-type inductor characterized in that a gap between both ends of a magnetic body formed between the coil-shaped conductor and the magnetic core is filled with an inorganic filler. 2. A winding core is formed by extrusion molding of a kneading material obtained by kneading a magnetic material powder and a binder, a conductor wire is wound around the winding core in a coil shape, and then the kneading material is extruded.
A core is formed by winding a conductor wire into a coil to form a jacket, and then the core and the jacket are fired and then cut into a predetermined length to embed the coil-shaped conductor in the magnetic core. A plurality of chip-shaped inductor bodies each having a magnetic core formed between the coil-shaped conductor of the chip-shaped inductor body and the magnetic core. A chip characterized by being filled with a paste composed of a filler and a solvent, and then applying and baking a conductive paste on both end faces of the magnetic core to form an external electrode connected to the exposed end of the conducting wire. Type inductor manufacturing method. 3. The core is selected such that the mixing ratio of the magnetic material powder and the binder in the core is smaller than or the same as the mixing ratio of the magnetic material powder and the binder in the casing. 2. The method for manufacturing a chip inductor according to claim 1, wherein the shrinkage rate during firing is set to be equal to or greater than the shrinkage rate of the jacket. 4. The shrinkage factor when firing the core is smaller than or equal to the particle size of the magnetic raw material powder of the core, and the shrinkage rate of the core during firing is 2. The method for manufacturing a chip-type inductor according to claim 1, wherein the shrinkage ratio is greater than or equal to