JPH0331061Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention relates to a laminated coil, and more particularly to a laminated chip variable coil with variable inductance.

[Conventional technology and problems]

The prior art will be explained with reference to FIGS. 6 to 20. 6 to 12 show the manufacturing process of the laminated coil portion of the laminated chip variable coil.
First, as shown in FIG. 6, a paste-like sheet or printed layer 8 is prepared by kneading an insulating ferromagnetic layer, generally ferrite powder such as Fe, Co, or Ni, and a suitable binder. The seat is sheet construction method,
For example, it is obtained by extruding material injected from a nozzle onto a belt while controlling the thickness using a manufacturing method called the doctor grade method. Further, the printed layer can be obtained by a well-known printing method. In the sheet method, after a desired layer such as a dielectric layer, a conductor layer, or a ferromagnetic layer is obtained, an electrode layer is applied, followed by pressure bonding and appropriate cutting to obtain a plurality of chips. A desired laminated electronic component is obtained by firing at a high temperature in a firing furnace. However, in the following explanation of the conventional example, each layer will be explained as being formed by a well-known printing method rather than the above-mentioned sheet construction method. Also, for convenience of explanation, one chip will be explained. On the surface of the ferromagnetic layer 8 obtained by the printing method, a conductor layer 9 for forming a coil of approximately half a turn is printed. The conductor layer is generally made of Ag,
A paste made by kneading metal powders such as Al, Cu, Ag-Pd, and Pd with a binder is used. In FIG. 6, part S is an electrode lead-out part. next,
The ferromagnetic layer 10 is printed leaving a part of the conductor layer 9, and the conductor layer 11 is connected to the conductor layer 9 and printed as shown in FIG. Moving on to the process shown in Figure 8, conductor layer 1
The ferromagnetic layer 12 is printed leaving a part of the ferromagnetic material layer 1, and the conductor layer 13 is connected to the conductor layer 11 and printed. If necessary, it is also possible to provide a lead-out portion b from the conductor layer 13 to form a laminated coil with a center tap. 9th
Moving on to the process shown in the figure, a ferromagnetic layer 14 is printed leaving a part of the conductor layer 13, and a conductor layer 15 is printed connected to the conductor layer 13 to provide an electrode extension portion F. In addition, in the above process, the number of turns and the number of stacked layers of the conductor layer can be adjusted arbitrarily. Further, the position of the drawer part b for the middle point tap can be adjusted as desired. 10th
Moving to the process shown in the figure, the ferromagnetic layer 16 is printed. After the lamination is completed, a hole 17 is punched through the center of the coil pattern formed by the conductor layers 9, 11, 13, and 15, as shown in FIG. 12th
The figure shows a perspective view of the laminated coil portion of the laminated variable chip coil obtained in the above process.

13 to 16 show the manufacturing process of the multilayer capacitor portion of the multilayer chip variable coil. First of all,
Dielectric layer 18 is printed as shown in FIG. The dielectric layer contains dielectric materials (BaTiO ₃ , TiO ₂
etc.) and formed into a paste with a binder. Next, a conductor layer 19 as an electrode layer
print. At that time, pull out one end of the conductor layer 19 to the lower right side of the dielectric layer 18, and
Let it be C ₁ . Moving on to the process shown in FIG. 14, the dielectric layer 2
Print 0. Next, the conductor layer 21 is printed. One end of the conductor layer 21 is pulled out to the left of the lower side of the dielectric layer 20 to form a lead-out portion _C2 , and then the dielectric layer 22
print. It is also possible to perform the process multiple times.

The laminated coil portion 26 and laminated capacitor portion 27 obtained in the above steps are compressed. If necessary, the laminated coil portion 26 and the laminated capacitor portion 27 are compressed via the layer 28. This layer 28 is
A layer that exhibits intermediate properties between a magnetic material and a dielectric material,
This is a layer to prevent cracks caused by sintering shrinkage in the next step, and is made of, for example, a mixed paste of dielectric powder and magnetic powder. Layer 28 can optionally be omitted. Laminated body 29 obtained as above
are fired in a firing furnace, and the drawer parts C ₁ , C ₂ , F,
Cover S with conductive paste and bake it to form external electrode 2.
3 and 24 are formed.

Next, as shown in FIG. 19, a threaded magnetic core 25 (for example, a core made of magnetic ferrite or the like) is screwed into the hole 17 to obtain a laminated variable chip coil. FIG. 20 shows a circuit diagram of a laminated chip variable coil according to the prior art.

In the laminated chip variable coil obtained as described above, the laminated coil portion 26 is of a closed magnetic circuit type,
There is little leakage magnetic flux in the screw hole of the magnetic core 25 that is screwed only into the hole 17 of the laminated coil portion 26. Therefore, there have been problems such as the range in which the inductance of the laminated coil can be adjusted by adjusting the magnetic core 25 is limited. That is, as shown in FIG. 19, in the conventional laminated chip variable coil,
The inductance is adjusted by adjusting the gap 28' created between the magnetic core 25 and the laminated coil portion 26, but the problem is that the adjustment range is narrow.

The laminated chip variable coil has a parallel circuit of inductance L and capacitor capacitance C', so that ₀ = 1/2π
It has a function to separate and select the center frequency ₀ of √. The laminated chip variable coil is used, for example, in a frequency characteristic guarantee circuit, a tuning circuit, or an oscillation circuit of an amplifier circuit. Generally, there are individual variations in electronic components such as capacitors and transistors in an electronic circuit, and it is desirable to be able to tune each laminated coil to a certain tuning frequency by adjusting a wide range of individual laminated coils in response to these variations. Therefore, the inductance of the laminated coil,
That is, it is desirable that the center frequency can be varied over a wide range and finely adjusted as necessary.

[Purpose of invention]

The purpose of the present invention is to allow the inductance of a laminated chip variable coil to be varied over a wide range.

Another object of the present invention is to enable fine adjustment of the inductance of a laminated chip variable coil.

Still another object of the present invention is to provide a laminated chip variable coil that can be produced inexpensively and in large quantities without significantly changing the manufacturing process of the prior art.

[Summary of the idea]

An overview of the present invention will be explained with reference to FIG.

The present invention includes a laminated coil portion 2 and a dielectric layer 3, and a through hole 30 passing through the laminated coil portion 2 and dielectric layer 3 is provided. Laminated coil part 2
is formed by alternately laminating ferromagnetic ferrite layers and conductor layers as in the conventional case. A dielectric layer 3 is formed at at least one location on this laminated coil portion 2 . This dielectric layer 3 is formed by alternately laminating conductors and dielectrics forming electrode layers, as in the conventional case. The ratio μ _C /μ _L between the magnetic permeability μ _C of the dielectric layer 3 and the magnetic permeability μ _L of the laminated coil portion is usually about 10 ⁻² to 10 ⁻⁴ . Therefore, the dielectric layer 3 serves as a path for the magnetic flux of the laminated coil portion 2, but because of its large magnetic resistance, it becomes an open magnetic path in terms of the magnetic circuit, and the magnetic flux leaks toward the through hole 30. The laminated coil portion is made of a ferromagnetic material, and its relative magnetic permeability ranges from several hundred to several thousand, or even more in some cases, and the strength of the magnetic field leaking from the dielectric layer toward the through hole is The strength is several hundred to several thousand times the strength of the leakage magnetic field, or even more. Therefore, the movable magnetic core 1 is inserted into the through hole 30.
By inserting and adjusting the insertion amount,
The amount of interlinkage between the magnetic core 1 and the magnetic flux is adjusted. Referring to FIG. 2, this magnetic core 1 is movable not only in the laminated coil section 2 but also in the dielectric layer 3. Therefore, the amount by which the leakage magnetic flux from the dielectric layer 3 interlinks with the magnetic core 1 can be greatly adjusted, and as a result, the inductance of the laminated chip variable coil can be changed significantly. Figure 3 shows the change in inductance of the laminated chip variable coil according to the present invention, and Figure 4 shows the frequency selection characteristics in that case, corresponding to the positions A, B, and C of each magnetic core in Figure 2. .

[Detailed description of preferred embodiments]

A preferred embodiment of the present invention will be described with reference to FIG. Note that the laminated coil portion 2 is formed by alternately laminating ferromagnetic layers and conductor layers, and the dielectric layer 3 is formed by alternately laminating dielectrics and conductors as electrode layers, and these are the same as in the conventional case. Therefore, I will not explain it in detail. After the laminated coil portion 2 and dielectric layer 3 are formed, they are compressed.
After that, the through hole 30 is punched. After that, it is integrally sintered in a firing furnace. Next, the electrode extension portion is coated with a conductive paste and baked to form the external electrode 7 and the like. A magnetic core member composed of the trimmer 4, the magnetic core 1, and the flange 6 is manufactured according to the diameter of the through hole 30. The trimmer 4 is made of a non-magnetic material, such as plastic or brass,
The magnetic core 1 is held under pressure. Further, the trimmer 4 is formed with a male thread, and the flange is formed with a female thread, so that the rotation of the trimmer 4 causes the magnetic core 1 to move up and down. This flange 6, like the trimmer 4, is made from a non-magnetic material. The magnetic core member having the above structure is fitted into the through hole 30 to obtain a laminated variable chip coil according to the present invention.

[Function and effect of the idea]

According to the present invention, the rotation of the trimmer 4 with respect to the flange 6 causes the magnetic core 1 to move up and down within the through hole 30, and the amount of interlinkage with the leakage magnetic flux from the dielectric layer is adjusted over a wide range. The inductance can be adjusted over a wide range. Therefore, the center frequency ₀ expressed by f ₀ =1/2π√ can be adjusted by changing the inductance L according to the variation in the capacitance C. This center frequency can therefore be made to coincide with a fixed tuning frequency in the reception stage of a radio, for example. Furthermore, since the magnetic core can be moved up and down by the threaded grooves of the flange and trimmer, the inductance can be finely adjusted. Therefore, it is possible to accurately adjust the desired frequency. Furthermore, since the present invention does not require any major modifications or changes to the prior art, it is possible to obtain a variable laminated chip coil that is inexpensive, robust, and has good characteristics without impairing the features of the conventional laminated coil.

As is clear from the above description, the number of laminated layers of the laminated coil portion, the number of turns of the conductor layer, and the pattern shape can be changed as necessary. Furthermore, in the detailed description of the preferred embodiment, the dielectric layer is provided at only one location in order to provide an open magnetic path portion, but it is also possible to provide the dielectric layer at multiple locations.

In addition, by appropriately combining the laminated chip variable coil according to the present invention with other electronic components,
It will be obvious to those skilled in the art that various applications and modifications are possible.

[Brief explanation of the drawing]

FIG. 1 is a principle diagram showing the principle of a laminated chip variable coil according to the present invention. FIG. 2 is a sectional view taken along line a-a' in FIG. 1. FIG. 3 is a graph showing changes in inductance corresponding to positions A, B, and C of the magnetic core in FIG. 2. FIG. FIG. 4 is a graph showing frequency selection characteristics corresponding to each position A, C of the magnetic core in FIG. FIG. 5 is a perspective view of a laminated chip variable coil according to the present invention. 6 to 12 are plan views showing the manufacturing process of a laminated coil portion according to the prior art. FIGS. 13 to 16 are plan views showing the manufacturing process of a multilayer capacitor portion according to the prior art. 17th
The figure is a perspective view showing how the laminated coil portion and the laminated capacitor portion of the prior art are compressed.
FIG. 18 is a perspective view of a conventional laminated chip variable coil after firing. FIG. 19 is a sectional view of a conventional laminated chip variable coil. FIG. 20 is an equivalent circuit diagram of FIG. 19. The names indicated by each number in the figure are listed below. Note that the same numbers indicate the same parts. 1...
... Magnetic core, 2 ... Laminated coil portion, 3 ... Dielectric layer, 4 ... Trimmer, 5 ... Internal electrode, 6 ... Flange, 7 ... External electrode, 8, 10, 12, 1
4, 16...Ferromagnetic layer, 9, 11, 13, 15
...Conductor layer, 17... Hole, 18, 20, 22...
Dielectric layer, 19, 21... Conductor layer, 23, 24...
...external terminal, 25...magnetic core, 26...multilayer coil part, 27...multilayer capacitor part, 28...
...Crack prevention layer, 29...Laminated body, 30...Through hole, S...Electrode lead-out part, F...Electrode lead-out part, _C1 ...Draw-out part, _C2 ...Draw-out part, b...
Drawer section (center tap).

Claims (1)

[Claims for Utility Model Registration] (1) A laminated coil portion consisting of a magnetic layer and a circulating conductor layer formed on the magnetic layer, and a laminated coil portion that overlaps at least one place in the laminated coil portion and is integrated into the laminated coil portion. In a multilayer chip variable coil comprising a formed dielectric layer and a through hole penetrating the magnetic layer and the dielectric layer, the through hole has a magnetic core having a thickness equal to or less than the thickness of the dielectric layer. A magnetic core member having a magnetic core member is movably inserted into the through hole at any position, and movement of the magnetic core member allows the magnetic core to completely move into the dielectric layer. A laminated chip variable coil characterized by adjustable inductance. (2) The magnetic core member includes the magnetic core, a trimmer integrated therein, a threaded portion of the trimmer, and a flange that is fixed to the dielectric layer and has a female threaded portion that engages with the threaded portion, and the trimmer and flange are non-contact. 2. The laminated variable chip coil according to item 1, which is made of a magnetic material and has a magnetic core that moves by rotation of a trimmer with respect to a flange.