JPH0727617Y2 - Multilayer chip inductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a multilayer chip inductor.

[Prior Art] In a multilayer chip inductor, one coil conductor is spirally formed in a ferrite magnetic body that is superposed by using the multilayer technology, and the start end and the end of each coil conductor are provided on different external electrode terminals. It is a chip-shaped inductor integrated so as to be connected.

In order to obtain multilayer inductors with the same outer dimensions and different inductance values, conventionally, (1) the material composition was changed to change the magnetic permeability of the material, or (2) the number of turns of the conductor coil inside the chip. Was done by either changing.

[Problems to be Solved by the Invention] However, when the method of changing the number of coil turns in the chip is adopted, the inductance value changes in proportion to the square of the number of turns (in the measured value, in proportion to approximately 1.6 to the number of turns). Therefore, it is not possible to cope with the case where different inductance values are required in smaller increments. On the other hand, if an attempt is made to compensate for the valley of the inductance value that cannot be accommodated by adjusting the number of turns by using materials with different magnetic permeability, the number of types of materials to be stocked will increase, resulting in reduced productivity and a disadvantage in cost. There were challenges.

Therefore, an object of the present invention is to solve the above problems and to provide a multilayer chip inductor which can be freely achieved even by controlling a minute inductance value that could not be conventionally produced because it cannot be dealt with by changing the number of coil turns in the chip. To provide.

[Means and Actions for Solving the Problem] As a result of research to achieve the above object, the present inventor has found that at least one turn at any position of a conductor pattern forming a coil incorporated in a chip is used for other portions. It was found that a fine control can be performed on the obtained inductance value if the line width is different from the above, and the present invention was reached.

Therefore, the present invention includes a coil, which is spirally formed by a thin layer conductor pattern arranged in a laminated manner and connected by through holes, inside a ferrite magnetic body. Is a laminated chip inductor having a structure in which each of the spiral coil is connected to another external electrode terminal provided at the end of the magnetic body, and at least one turn forming a part of the spiral coil at any position. It is intended to provide a laminated chip inductor, in which a conductor for a wire has a coil wire width different from that of other portions.

In the closed magnetic circuit inductor, the inductance value L is L
There is a relationship of ∝S / l. Where S is the cross-sectional area of the magnetic path,
l is the length of the magnetic path. On the other hand, in a chip having a constant outer dimension, S is determined by the coil line width, so the chip inductance value can be controlled by the coil line width.

2 (a) and 2 (b) are views showing the state of an internal conductor coil having 5 turns in a cross section perpendicular to the longitudinal direction of the chip element. FIG. 2 (a) is a conventional coil, FIG. FIG. 3B is a sectional view showing a coil having a large line width of, for example, 2 turns based on the present invention.

That is, as shown in FIG. 3B, when the line width of the internal conductor coil 2 built in the ferrite magnetic body 1 is increased (or decreased), the cross-sectional area of the magnetic path is decreased (or increased), and the inductance value is correspondingly increased. Becomes smaller (or larger). Therefore, even if it is required to change the minute inductance value that cannot be handled by changing the number of turns,
This can be easily handled by controlling the line width and increasing or decreasing the number of turns of the coil whose line width is changed.

It should be noted that the effect of the wide (or narrow) coil provided for controlling the inductance value does not change even if it is provided at any arbitrary position.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples.

[Embodiment] FIGS. 1A and 1B are perspective views for explaining a manufacturing process of a multilayer chip inductor according to an embodiment of the present invention, which will be described below with reference to these drawings.

(1) Fe ₂ O ₃ 48 mol%, ZnO 24 mol%, NiO 18 mol%, CuO
The raw material for the ferrite magnetic material, which is weighed at a ratio of 10 mol%, is wet mixed for 15 hours in a ball mill.

(2) The obtained mixture is dried and pulverized, and then calcined at 700 to 800-for 1 hour.

(3) After the wet calcining of the calcined material for 15 hours in a ball mill,
Dry and crush.

(4) To the resulting material powder, 10 to 15% by weight of a binder, 20% by weight of toluene, 20% by weight of ethanol and 40% by weight of butanol are added, and mixed for 15 hours with a ball mill.

(5) The obtained slurry is formed into a long green sheet having a film thickness of 50 to 80 μm by using a doctor blade method.

(6) Next, through holes 4 are provided at necessary places in the green sheet piece 3 cut into an appropriate size, and then Ag paste 5 is applied by screen printing to form a pattern for the internal coil. At this time, as shown in FIG. 1 (a), a pattern in which the line width of some coils is increased is printed. Usually, a plurality of patterns are printed on the sheet of each layer so that a large number of inductors can be formed at the same time, but one inductor is shown for simplicity of explanation.

(7) The pattern-printed sheets obtained are stacked in a number (6 turns in the drawing, of which 2 have a large line width) to obtain the desired number of windings, and a molded body is formed with a pressure of 0.5 t / cm ^2. 6 is obtained (see FIG. 2B).

(8) The molded body is cut into chips, separated from each other by a binder removal treatment at 500 ° C. for 1 hour, and then fired at 850 to 900 ° C. for 1 hour.

(9) An external electrode is applied to the obtained fired body with an Ag paste by a dipping method, dried at 150 ° C. for 15 minutes, and then fired at 600 ° C. for 10 minutes to obtain a multilayer chip inductor.

As described above, a product in which the total number of turns was 6 to 10 and the coil wire width was partially changed to 0.40 mm or 0.50 mm was manufactured as a prototype, and the inductance values thereof were measured and shown in Table 1.

FIG. 3 is a cross-sectional view showing the state of the coil in the cross-section of the chip element. FIGS. 3B to 3D show the inductor of the present invention shown in the embodiment. In FIG. 3B, the coil wire width is w ₁ = 0.30 mm. 5 turns, and w ₂ = 0.40mm, 2 turns, example (c)
An example of 5 turns at w ₁ = 0.30 mm and 2 turns at w ₃ = 0.50 mm is shown, and (d) shows an example of 3 turns at w ₁ = 0.30 mm and 4 turns at w ₂ = 0.40 mm. FIG. 3A shows a conventional example in which the coil wire width of all turns is w ₁ = 0.30 mm.

[Comparative Example] A green sheet was prepared by adjusting the material for the ferrite magnetic material according to the procedure shown in the example, and the obtained green sheet piece 3 was used for the internal coil as shown in Fig. 4 (a). Ag paste 5 was printed. However, in this case, a pattern in which the line width was changed was not provided in a part of the coil pattern, and all had the same line width. In the same manner as in the case of the following embodiment, FIG.
A molded body 6 as shown in (1) was further cut, and after cutting into chip elements, external electrodes were applied and formed thereon, and baked to obtain a laminated chip inductor. At this time, the total number of turns is 6
A chip having a line width of 0.30 mm was produced for ~ 10 and its inductance value was obtained. The results are also shown in Table 1.

[Effect of the Invention] As described above, according to the multilayer chip inductor of the present invention, the inductance value proportional to the square of the number of turns is the same for the same shape, the same material (that is, the same magnetic permeability) and the same number of turns. Although it was not obtained, it became possible to control the minute inductance value that could not be dealt with by changing the number of turns.

[Brief description of drawings]

1 (a) and 1 (b) are perspective views for explaining a manufacturing process of a multilayer chip inductor according to an embodiment of the present invention. 2 (a) and 2 (b) are cross-sectional views for explaining the relationship between the coil wire width and the inductance value of the chip element. FIG. 2 (a) is a conventional coil, and FIG. 1 shows a coil according to the invention. FIG. 3 is a sectional view similar to FIG. 2, in which FIG. 3A shows a conventional example using a coil having a line width of 0.30 mm, and FIG.
(D) shows a coil having a partial line width of 0.40 mm or 0.50 mm used in the embodiment of the present invention. 4 (a) and 4 (b) are perspective views for explaining a manufacturing process of a conventional multilayer chip inductor. Explanation of code 1 …… Ferrite magnetic material 2 …… Coil 3 …… Green sheet piece 4 …… Through hole 5 …… Ag paste 6 …… Molded body w ₁ …… Coil wire width (0.30mm) w ₂ …… Coil Wire width (0.40mm) w ₃ ... Coil wire width (0.50mm)

Claims (1)

[Scope of utility model registration request] 1. A ferrite magnetic body includes a coil formed in a spiral shape by thin layered conductor patterns arranged in a laminated form and connected by through holes, and a start end and an end of the coil are included. Is a laminated chip inductor having a structure in which each of the spiral coil is connected to another external electrode terminal provided at the end of the magnetic body, and at least one turn forming a part of the spiral coil at any position. A multilayer chip inductor characterized in that the conductor of the minute wire has a coil wire width different from that of other portions.