JPH1050523A - Impedance device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impedance device which can easily control the impedance to a target value in a specified high-frequency region, without distinction of shape and whose magnetic material can be used for components of different impedance value and to provided method for manufacturing the same. SOLUTION: A magnetic substance 2 is formed by laminating alternately ceramic paste of oxide magnetic powder and conductive paste of metallic powder. Spiral coils 1 of conductive paste are formed in the magnetic substance 2 and fired in one piece to form a multilayer component. A resistor device of a film of conductive substance formed on the surface of the multilayer device and n impedance device connected in parallel to the ends of the spiral coils are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer impedance element for reducing noise in a signal circuit and reducing signal wave distortion and delay, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, as a measure against EMI of electronic equipment, it has been generally practiced to insert an impedance element in series in a signal system to cut off noise.

[0003] In a power supply line system such as a power amplifier, an impedance element is inserted in series to suppress the leakage of signal system noise from the active element to the power supply line.

However, the countermeasure against EMI by the impedance element has a negative effect that a reactance component causes distortion of a signal waveform or causes a phase delay.

The impedance Za of the impedance element
Is a combination of the real-valued resistance component Ra and the imaginary-part reactance component Xa, and is expressed by the equation Ra + jXa. An ideal impedance element that is effective for noise absorption and does not cause distortion or phase lag has a large resistance component Ra in a real part in a specific high frequency region having a noise component, and has a real part in a frequency region in a signal range. The resistance component Ra and the imaginary part reactance component Xa have frequency characteristics indicating small values.

[0006]

A specific value of the resistance value in a high-frequency region that affects noise absorption is required depending on the circuit used. Today, the element used for this purpose is realized by adjusting the frequency characteristic of the inherent loss of the magnetic material and adjusting the number of turns of the formed spiral coil as means for approaching the desired frequency characteristic. The loss characteristics of materials such as ferrite have a low degree of freedom, and the problem is that the desired frequency characteristics cannot always be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide an impedance element which can easily control an impedance value to a target value in a specific high-frequency region, and one magnetic material can be used for elements having various impedance values, and a method of manufacturing the same. It is in.

[0008]

According to the present invention, a ceramic paste comprising an oxide magnetic material is laminated, and the ceramic paste and the conductor paste are alternately laminated thereon.
A conductor is formed in a spiral coil shape, and the ceramic paste is laminated thereon to form a laminate, the laminate is fired, and a film made of a conductive substance formed on the surface of the laminate, An impedance element characterized by being connected in parallel with both ends.

Further, the present invention is characterized in that, as a means for forming the film, the surface of an element made of an oxide sintered body is partially reduced to form a film having a predetermined conductivity. This is a method for manufacturing an element.

[0010]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a parallel circuit of an inductance L and a resistance R. The impedance between the terminals of this circuit is given by the equation:

Z = (ω ² L ² R + jωLR ² ) / (R ² + ω ² L ² )

In the impedance element of the present invention, a ceramic paste and a conductor paste are alternately laminated, a conductor is formed in a spiral coil shape, and the ceramic paste is laminated thereon to form a laminate. To obtain a target frequency characteristic by forming a film made of a conductive material of a resistance element on the surface of the laminate, and forming a composite element in which the film and both ends of the spiral coil are connected in parallel. Can be.

The value of the inductance L of the circuit is 1 μm.
H or 2 μH, and the value of the resistor R of the circuit is 500
In the case of Ω, the frequency characteristics of the impedance Z1 between the two terminals, the resistance component R1 of the real part thereof, and the reactance component X1 of the imaginary part thereof are shown in FIG. 2 as curves of A1, B1, C1, D1, E1, and F1, respectively. .

A1 shows the frequency characteristic of the impedance Z1 when the resistance R of the circuit is 500Ω and the inductance L of the circuit is 1 μH. B1 is the resistance R of the circuit is 500Ω
Shows the frequency characteristic of the resistor R1 in the real part when the inductance L of the circuit is 1 μH. C1 is the resistance R of the circuit is 500
Ω indicates the frequency characteristic of the reactance component X1 of the imaginary part when the inductance L of the circuit is 1 μH. D1 indicates the frequency characteristic of the impedance Z1 when the resistance R of the circuit is 500Ω and the inductance L of the circuit is 2 μH. E1 is that the circuit resistance R is 500Ω and the circuit inductance L is 2μ.
The frequency characteristic of the resistor R1 in the real part when H is shown. F1 is
The frequency characteristic of the imaginary part reactance component X1 when the resistance R of the circuit is 500Ω and the inductance L is 2 μH is shown.

The value of the inductance L of the circuit is 1 μm.
H or 2 μH, and the value of the resistance R of the circuit is 300
Ω, the impedance Z between both terminals
2 and its real part, the resistance component R2, and the imaginary part, the reactance component X2, are represented by A2, B2, C2, D2,
FIG. 3 shows curves of E2 and F2.

A2 shows the frequency characteristic of the impedance Z2 when the resistance R of the circuit is 300Ω and the inductance L of the circuit is 1 μH. B2 indicates that the resistance R of the circuit is 300Ω.
Shows the frequency characteristic of the resistance component R2 of the real part when the inductance L of the circuit is 1 μH. C2 indicates that the resistance R of the circuit is 3
9 shows the frequency characteristic of the reactance component X2 of the imaginary part when the inductance L of the circuit is 1 μH at 00Ω. D2 has a circuit resistance R of 300Ω and a circuit inductance L of 2μ.
The frequency characteristic of the impedance Z2 at the time of H is shown. E2
Means that the circuit resistance R is 300Ω and the circuit inductance L
4 shows the frequency characteristic of the resistance component R2 of the real part when is 2 μH. F2 is a reactance component X2 of an imaginary part when the resistance R of the circuit is 300Ω and the inductance L of the circuit is 2 μH.
FIG.

As is clear from FIGS. 2 and 3, in the low frequency region, the impedance value of the coil portion having a low impedance value is dominant, and the impedance value between the two terminals is determined. When the impedance value exceeds the resistance of the circuit, the impedance value between the two terminals is dominated by the resistance component of the real part and converges to the value of the resistance component of the real part.

Further, it is possible to change the rise of the impedance value by the frequency characteristic of the impedance value depending on the inductance value.

When the impedance element is manufactured by using a magnetic material such as ferrite for the core, the reactance component decreases as the frequency increases, and the loss increases at the same time.

As a result, the frequency characteristic of the impedance value shows a change similar to the frequency characteristic of the above-described parallel circuit of the pure inductance L and the resistor R.

However, when a desired frequency characteristic is obtained,
The frequency characteristics are controlled mainly by the loss characteristics of the material.
In other cases, the degree of freedom is small due to the number of turns of the spiral coil and the inductance value obtained by adjusting the shape, and a desired frequency characteristic is not always obtained.

However, when a resistor is connected in parallel with the inductance element, the component of the real part of the impedance in the high frequency region shows the effect of connecting in parallel with the resistor, and controls the component of the real part of the impedance. It is possible to control the resistance value in the high frequency range very easily.

However, it is not preferable to newly add a resistance element in terms of downsizing of components and surface mounting work because of an increase in man-hours. If a resistance element can be formed on the surface of the inductance element, it is possible to provide an extremely practical impedance element.

[0025]

An embodiment of the present invention will be described.

As a ceramic powder, a Ni—Cu ferrite powder was prepared. This powder is used as a binder,
It was blended with the solvent at a ratio shown in Table 1, and the blend was kneaded with a three-roll mill to prepare a ceramic paste composed of an oxide magnetic material.

[0027]

As a conductor powder, a mixed powder of Ag and Pd (Ag 70%, Pd 30%) having an average particle size of 0.5 μm was prepared.

This powder was mixed with a binder and a solvent in the ratios shown in Table 2 and kneaded with a three-roll mill to prepare a paste for a conductor.

[0030]

Next, the produced ceramic paste was laminated to a predetermined thickness of 500 μm by a printing method. On top of this, using ceramic paste and conductor paste,
A 3.5-turn spiral coil of a conductor is formed and sequentially laminated, and a ceramic paste is applied on top of this.
The layers were laminated by a printing method of μm.

The above-prepared laminate has a predetermined size (2.
4 mm x 1.5 mm), and after degreased, 9
It was baked at 50 ° C. FIG. 4 shows an internal structure of an element including the coil 1 and the magnetic body 2. A conductive paste mainly composed of Ag was applied to the surface of the coil 1 where the lead portions were exposed to form external terminals. The element in this state was designated as Sample A.

Next, after a thin carbon is deposited on the ceramic surface between the electrode terminals, the DC resistance between the terminals is set to 180Ω by a trimming device while measuring the resistance using a DC resistance meter.
The sample adjusted to the above was designated as Sample B.

Further, the external terminal was formed and heat-treated in a ring furnace in a hydrogen atmosphere at 700 ° C. for 30 minutes and for 10 minutes. The DC resistance between the terminals of this sample was measured to be 480Ω and 9Ω, respectively.
A 70Ω resistance value was confirmed. These were designated as Samples C and D.

The frequency characteristics of the impedance of the multilayer inductor manufactured as described above were evaluated using a YHP impedance analyzer HP4191A. The results of Sample A, Sample B, Sample C, and Sample D are shown in FIG.
6, 7, and 8.

As shown in FIG. 5, ZA indicates the frequency characteristic of the impedance ZA of the sample A when no resistance element is added. RA indicates the frequency characteristic of the resistance component RA of the real part of the sample A when no resistance element is added. XA indicates the frequency characteristic of the reactance component XA of the imaginary part of the sample A when no resistance element is added.

As shown in FIG. 6, ZB indicates the frequency characteristic of the impedance ZB of the sample B. RB indicates the frequency characteristic of the resistance component RB of the real part of the sample B. XB is sample B
5 shows the frequency characteristic of the reactance component XB of the imaginary part of FIG.

As shown in FIG. 7, ZC indicates a frequency characteristic of the impedance ZC of the sample C. RC indicates the frequency characteristic of the resistance component RC of the real part of the sample C. XC is the sample C
5 shows the frequency characteristic of the reactance component XC of the imaginary part of FIG.

As shown in FIG. 8, ZD indicates the frequency characteristic of the impedance ZD of the sample D. RD indicates the frequency characteristic of the resistance component RD of the real part of the sample D. XD is sample D
5 shows the frequency characteristic of the reactance component XD of the imaginary part of FIG.

In FIG. 5, the impedance value of the sample A in the high frequency region (> 50 MHz) of about 200 Ω in which no resistance element is added is determined by the frequency characteristic and the element shape of the loss coefficient of the NiZn ferrite. Get involved. However, in the case of a surface-mounted component, there are many dimensional restrictions on the element shape, and it is not easy to control impedance characteristics at high frequencies.

On the other hand, in the case of Samples B, C, and D shown in FIGS. 6, 7, and 8, the impedance value in the high frequency region is almost controlled by the value of the added resistance element. In addition, it has been proved that impedance characteristics in a high frequency region can be controlled very easily.

Further, it was confirmed that a conductive layer was formed on the element surface by heat treatment in a reducing atmosphere from Samples C and D, and that this could be used as a resistance element, and that the resistance value could be controlled by the heat treatment conditions.

[0043]

As described above, according to the present invention, the impedance element, which is an SMD component having many restrictions on the shape and size, is not controlled by the shape of the impedance value to a desired value in a specific high-frequency region, and is easily controlled. It has become possible to provide an element which can be controlled at a high speed and a method for manufacturing the same. or,
The present invention has an advantage that one magnetic material can be used for elements having various impedance values and a method for manufacturing the same, which is an industrially extremely useful invention.

[Brief description of the drawings]

FIG. 1 is a diagram showing a parallel circuit including an inductance L and a resistance R.

FIG. 2 shows a case where the value of the inductance L of the circuit is 1 μH or 2 μH and the value of the resistance of the circuit is 500Ω, the impedance Z1 between both terminals thereof, the resistance component R1 of the real part thereof, and the resistance of the imaginary part thereof. The figure which shows the frequency characteristic of the reactance component X1.

FIG. 3 is a graph showing the relationship between the impedance Z2 between both terminals of the circuit and the resistance component R2 of the real part and the imaginary part of the circuit when the inductance value of the circuit is 1 μH or 2 μH and the resistance value of the circuit is 300Ω. The figure which shows the frequency characteristic of the reactance component X2.

FIG. 4 is a perspective view showing a sample A.

FIG. 5 is a diagram illustrating frequency characteristics of a sample A;

FIG. 6 is a diagram illustrating frequency characteristics of a sample B;

FIG. 7 is a diagram illustrating frequency characteristics of a sample C;

FIG. 8 is a diagram illustrating frequency characteristics of a sample D;

[Explanation of symbols]

 1 coil 2 magnetic material

Claims (2)

[Claims] 1. A ceramic paste made of an oxide magnetic material is laminated, a ceramic paste and a conductor paste are alternately laminated thereon, a conductor is formed in a spiral coil shape, and the ceramic paste is laminated thereon. An impedance element, comprising: forming a laminate, firing the laminate, and connecting a film made of a conductive substance formed on the surface of the laminate and both ends of the spiral coil in parallel. 2. The means for forming a film according to claim 1,
A method for manufacturing an impedance element, comprising forming a film having a predetermined conductivity by partially reducing the surface of an element made of a sintered oxide.