JP2000294422A - Laminated inductive element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To have superior inductance and to strengthen against impairment noise by so connecting a conductive thick film line in a direction along which a current flows through the conductive thick film line having a facing part via a soft ferrite layer to be in an opposite direction at the facing parts each other. SOLUTION: A first layer on which a pattern made of ferrite 2 is laminated. One terminal of the pattern is connected with a land 6 with a conductive thick film line 3, another is connected with a terminal of both terminal part 5 and additionally with an outer electrode, the land 6 is connected with a through hole electrode 4 and the through hole electrode is connected with a land on a next second layer. The next second layer is connected with both terminals of the conductive thick film line 3, the one of the land 6 is connected with the through hole electrode 4 of the first layer, the other is connected with the through hole electrode 4 of this layer and additionally the through hole electrode of this layer is connected with the land 6 of a next third layer. The position of the through hole electrode 4 is made different from one of the previous layer (the second layer). Further, a next fourth layer is made the same as the previous previous layer (the second layer).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated integrated sintering type induction element which uses soft ferrite and is used for noise suppression in high frequency transmission circuits and the like.

[0002]

2. Description of the Related Art In a laminated induction element, an electrode pattern, that is, a conductive thick film line and a connector, for example, a through hole, are formed on a green sheet formed by using soft ferrite or the like. It is a small electronic component obtained by firing, and is widely used from low frequency to microwave band. The most common of the stacked induction elements are, for example, coils and transformers.

[0003] The case of a laminated coil will be described.
First, a part of the coil is formed by a conductive thick film line on one layer, and another part of the coil is formed by a conductive thick film line on an adjacent layer so as to extend the coil. Connect with. By repeating this operation, a solenoid-shaped coil is formed.

[0004] The case of a laminated transformer will be described.
First, a part of the coil is formed on each of the two layers by a conductive thick film line. On the layer adjacent to each of these layers, another part of the coil is formed by a conductive thick film line so as to extend the coil of the layer separated by one, and these are connected to each other by through holes every other layer. I do. By repeating this operation, a laminated transformer (also referred to as a laminated transformer) in which primary coils and secondary coils are alternately laminated is completed. This laminated transformer also becomes a common mode choke if one end of the primary coil and one end of the secondary coil are set as the input side and the other ends are set as the output side.

[0005] The basic structure of these conventional laminated coils and transformers is very similar to the configuration of the originally wound coils and transformers, and simply replaces the method of winding parts with the method of lamination. It may be said. Since the currents flowing through the coils of each layer are in the same direction as each other, the magnetic field generated by these currents forms a common large magnetic flux, and the coils are strongly coupled magnetically by sharing the magnetic flux. It is expected that a large inductance can be obtained by exhibiting an inductive effect.

On the other hand, such a conventional laminated component has a drawback that it is inherently weak against external magnetic or electric disturbance noise. That is, it is susceptible to the effects of noise and magnetic fields in the same direction as the current and magnetic flux. This difficulty was more pronounced at higher frequencies. That is, since the high frequency has a small wavelength, it is easy to dimensionally tune with a small electronic component, and the high frequency has a small magnetic permeability because the magnetic permeability of the ferrite material is small.

[0007] Although the structure is weak against external disturbances as described above, there is also a problem in terms of self-induction and mutual induction. That is, in the case of a laminated coil or laminated transformer using soft ferrite, since the ferrite layer exists between the layers of the coil, most of the magnetic flux generated by the coil passes through the ferrite portion between the coil layers and Since it is difficult to form a circuit, it becomes an electronic component having weak magnetic coupling, and it has been difficult to obtain a coil having a low inductance, a transformer having a low conversion efficiency, a common mode choke having a small effect of suppressing common mode noise, and the like.

[0008] The fact that the magnetic coupling is weak against external disturbance is not solved even if the magnetic coupling is strengthened by any method in consideration of such a situation on the magnetic circuit as long as the above technique is used. . This is because the electric field or magnetic field of the external disturbance usually comes from a distance, that is, from almost one direction, and has a sensitivity according to the component structure regardless of a local magnetic circuit.

On the other hand, in the prior art other than the multilayer electronic component, as a means for avoiding the external disturbance as described above, there is a method of folding and twisting an excess portion of one electric wire in order to prevent induction of the electric wire. . In this method, currents induced by external disturbances cancel each other out in an electric circuit. Therefore, there is little guidance to electric wires. The drawback of this method is that it does not become an inductive element because there is no self-induction.

As described above, conventionally, there is no laminated inductive element having excellent inductivity and high resistance to disturbance noise, and development of this element has been awaited.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated inductive element having excellent inductive properties and resistant to disturbance noise.

[0012]

Means for Solving the Problems As a result of earnest studies to solve the above-mentioned problems, the present inventors have conceived of a laminated inductive element having a remarkably improved configuration and characteristics. That is, the first invention of the present application connects the conductive thick film lines so that the directions of currents flowing through the conductive thick film lines having the opposing portions via the soft ferrite layer are opposite to each other at the opposing portions. This is a laminated inductive element configured as follows.

The most novel and characteristic features of the present invention are:
The points where currents flowing in parallel opposing portions of the conductive thick-film line of the transformer / transformer or coil are arranged so that the directions of the currents are opposite to each other, for example, the conductive thick-film line becomes substantially folded. That is the point. This configuration is effective only in a laminated induction element mainly made of a magnetic material. For example, even if this structure is applied to a conventional winding transformer or a winding type coil, no improvement in characteristics can be expected.

That is, in this configuration, a ferrite layer is disposed at a portion sandwiched between the opposing conductive thick film lines, and the magnetic flux turns short-circuited through the ferrite layer. On the other hand, the currents induced by the external disturbance electromagnetic waves cancel each other because they flow in the same direction in the opposing conductive thick film lines, and thus are not affected by the external disturbance electromagnetic waves. Note that the current referred to in the present invention has a high frequency,
The direction of the current referred to in the present invention has no meaning other than indicating the connection direction of the line.

According to a second aspect of the present invention, in the first aspect, the thickness of the soft ferrite layer at a portion where the conductive thick film line faces is equal to the distance between the lines of the conductive thick film line facing the same surface. This is a stacked inductive element configured to be 0.5 times or less the distance. In the present invention, the content of the present invention is made more specific by defining the ratio of the magnetic flux flowing through the ferrite layer between the conductor lines in the first invention in more detail.

Further, a third invention of the present application is one in which a multilayer noise filter is constituted by the multilayer inductive element according to the first or second invention. The magnetic flux of the ferrite layer between the conductive thick film lines is the same as that of the first invention, but a large inductance is obtained by strong self-induction because the adjacent coils are connected in series and in the opposite direction. The noise emission to the outside is small and it is hardly affected by external disturbance electromagnetic waves.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below based on embodiments. FIG. 1 is an exploded perspective view for explaining the present invention. In FIG. 1, the arrangement of the conductive thick film line and the magnetic circuit of the present invention are drawn in the following manner so as to be clearly understood. The hatched portion indicates a conductive portion such as a conductive thick film line and a through hole. External electrodes are omitted. The thickness of each electrode is not shown. Although the ferrite layer is actually integral, it is divided and drawn at a position corresponding to the position before lamination and pressure bonding, and the positional relationship is easily understood by drawing with a size divided into component sizes. In addition, what is shown in this figure regarding the scale and number of each part is only one example.

[0018]

Next, a method of manufacturing a laminated inductive element according to the present invention will be described below in accordance with embodiments.

Example 1 Commercially available Fe, Ni, Cu, C
O, Zn, Bi, Mn, Si, etc., each oxide powder is weighed in a predetermined amount, mixed well with a ball mill, and this mixed powder is calcined in an atmosphere of 800 ° C., pulverized with a ball mill, and ferrite powder. A powder was obtained. It goes without saying that powders having different magnetic properties can be obtained by changing the type and amount of the oxide.

This powder was well mixed with a dispersant, a plasticizer, a solvent and the like to form a slurry. The obtained slurry was formed into a sheet having a thickness of 60 μm by a doctor blade method. The sheet before firing is called a green sheet. A through hole having a diameter of 0.2 mm was formed in a predetermined position of the green sheet, and a predetermined pattern was formed by a screen printing method using a commercially available Ag paste. Ag is also filled into the through-hole portion at the same time as the pattern is formed to form a through-hole electrode.

The green sheets having the above-described patterns formed thereon were sequentially stacked and heated and pressed, and then cut at predetermined positions into a vertical width of 1.2 mm and a horizontal width of 0.6 mm to obtain chips before firing. Further, Ag was applied by a printing method using Ag paste to predetermined positions on both sides and side surfaces of the chip before firing, which were to be external electrodes, and fired at 900 ° C. in the air. A Ni layer was formed on the external electrodes of the fired chip thus obtained, and a solder layer was formed on the outer surface thereof by plating to obtain a finished part.

Example 2 A laminated inductive element was prepared as shown in FIG. 1 with the pattern of Example 1 and the shape and combination of the through-hole electrodes, and the others as described in Example 1. This laminated inductive element is a laminated noise filter. The thickness of the conductive thick film electrode is 18 μm, the width is 70 μm, the interval between the conductive thick film electrodes facing each other via the ferrite layer of the conductive thick film electrode is 35 μm, and the interval between the conductive thick film electrodes facing each other in the same plane is 85 μm.

The dummy sheet (1) is a plain layer made of ferrite (2). One or more (two in FIG. 1) dummy sheets (1) are stacked, and then a sheet (first layer) on which the first pattern is printed is stacked. This pattern is a meander type conductive thick film line (3), one of which is connected to the land (6), the other is connected to one end of both ends (5), and further connected to external electrodes (not shown). The land (6) is connected to the through-hole electrode (4), and the through-hole electrode is connected to the land of the next layer (second layer).

In the next layer (second layer), lands (6) are provided at both ends of the meander type conductive thick film line (3). One of the lands (6) is connected to the through-hole electrode (4) of the previous layer (first layer) and the other is connected to the through-hole electrode (4) of this layer (second layer). Is connected to the land (6) of the next layer (third layer).

The next layer (third layer) has the same structure as the previous layer (second layer), but the position of the through-hole electrode (4) is switched from that of the previous layer (second layer). The next layer (fourth layer) is the same as the layer before the second layer (second layer). Further front layer (third layer)
The same layer as the layer before the second layer (the second layer) is appropriately repeated (0 in FIG.
(0 to 4 times in the second embodiment), the final pattern is formed in the same manner as the first pattern, and both ends (5)
To the other end and to an external electrode. After the layer (fifth layer) on which the final pattern is formed, an appropriate number (only one is shown in FIG. 1) of dummy sheets (1) are arranged. The total number of upper and lower dummy sheets (1) was distributed so that the total number of laminated sheets would be 16 layers, and the pattern forming layer would be near the center.

In the second embodiment, the conductive thick film line (3) of each layer is connected to the through-hole electrode (4) in the manner described above, so that the current flows through the conductive thick film line (3) of one layer. The direction of the current (eg, direction A) is opposite to the direction (eg, direction B) of the current flowing through the opposing portion of the conductive thick film line (3) in the adjacent layer.

FIG. 2 is a part of a cross section orthogonal to the conductive thick film line (3) for explaining the directional relationship between the current and the magnetic flux in the second embodiment. However, the scale of the figure is not accurate. Reference numerals in the figure are the same as those in FIG. It can be seen that the direction of the magnetic flux induced by the current flowing through the pair of opposing conductive thick film lines (3) in the ferrite (2) layer between the conductive thick film lines (3) coincides with one direction.

In the same steps and in the same manner as described above, the pattern is changed for even number layers (second layer, fourth layer...)
What was formed like this was created as a comparative example. The directions of the currents flowing through the opposing conductive thick film electrodes via the ferrite are the same as each other. Table 1 shows the results of evaluating and comparing the characteristics of the multilayer induction element of Example 2 and the multilayer induction element prepared in the comparative example as a noise filter.

[0029]

[Table 1]

In Table 1, samples Nos. 1 to 5 are examples of the present invention, and samples Nos. 6 and 7 are comparative examples described above. According to Table 1, there is a great difference between the present embodiment and the comparative example, even though the structures are apparently similar with the same number of layers. That is, the absolute value | Z | of the impedance at a frequency of 1 GHz was approximately doubled by employing the structure of the present invention. That is, a large inductivity is obtained. Further, the resonance frequencies fr are substantially the same. This indicates that the present invention also has the effect of reducing the capacitance component of the component.

The attenuation factor of the noise measured by inserting the component of the present invention and the component of the comparative example prepared in Example 2 into the transmission line is 3 to 4 dB larger in the product of the present invention than in the comparative example, and the noise suppressing effect is obtained. Improvement was confirmed. Further, a radio wave of 1 GHz is transmitted from a distance of about 3 m, and the voltage at both ends of these sample parts is measured by observing a meter to check the reception state. The result of the disturbance shown in Table 1 is shown in Table 1.

As shown in Table 1, the comparative example had the receiving sensitivity, whereas the product of the present invention did not have the receiving sensitivity. In other words, it was clarified that the product of the present invention is resistant to external disturbance.

[0033]

As described in detail above, according to the present invention, a laminated inductive element having excellent inductivity and resistant to disturbance noise can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a laminated inductive element according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a relationship between current and magnetic flux according to the present invention.

FIG. 3 is an exploded perspective view of a laminated inductive element according to a comparative example of the present invention.

[Explanation of symbols]

 Reference Signs List 1 dummy sheet 2 ferrite 3 conductive thick film line 4 through-hole electrode 5 both ends

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuo Tani 70-2, Minamisakaemachi, Tottori City, Tottori Prefecture F-term in Hitachi Metals Co., Ltd. Tottori Plant 5E043 AA08 AA09 AB09 BA01 5E070 AA01 AB01 AB03 AB10 BA12 CB03 CB13 CB17 CB20 EA01 EB03

Claims (3)

[Claims] 1. A conductive thick film line is formed by connecting conductive thick film lines so that the directions of currents flowing through the conductive thick film lines having opposing portions via a soft ferrite layer are opposite to each other at the opposing portions. A laminated induction element, characterized in that: 2. The inductive element according to claim 1, wherein the thickness of the soft ferrite layer at a portion where the conductive thick film line faces is 0.5 times or less of a distance between the conductive thick film lines facing each other on the same surface. The laminated induction element according to claim 1, wherein the laminated induction element is configured as follows. 3. The multilayer induction element according to claim 1, wherein the multilayer induction element is a multilayer noise filter.