JPH10270255A - High-frequency chip bead element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-frequency chip bead element possessed of high-frequency cutoff and low-frequency transmission characteristics by a method, wherein the high-frequency chip bead element is composed of an insulating base and at least a signal conductor, the insulating base is a composite member which is a mixture of ferrite powder and insulating resin, and the signal conductor is embedded in the insulating base in a spiral form. SOLUTION: An insulating base 1 is formed of composite member of a mixture of ferrite powder and insulating resin. A signal conductor 2 is embedded in the insulating base 1 in a spiral form. The insulating base 1 is equipped with terminal electrodes 51 and 52, provided to both its opposed edge faces for external connection. The signal conductor 2 is wound providing a space between its winding conductors in a direction vertical to a straight line drain between the terminal electrodes 51 and 52. A space between the winding conductors is set larger than the diameter of the wire of the signal conductor 2. The ends of the signal conductor 2 are connected to the terminal electrodes 51 and 52 respectively. By this setup, an unwanted high-frequency component in a high-frequency region contained in frequency signals which pass through the signal conductor 2 can be surely absorbed by the absorbing action of the insulating base 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-frequency chip bead element, and more particularly to a high-frequency chip bead element having a noise absorption characteristic in a GHz band.

[0002]

2. Description of the Related Art A high-frequency chip bead element of a low-pass type (high-band rejection type) is typically a low-pass filter. A conventional general low-pass filter uses a difference in frequency characteristics between impedance matching and mismatching, and reflects a signal belonging to a high-frequency side frequency band to obtain a necessary filter characteristic. It has gained. However, in a reflection-type low-pass filter, reflected unnecessary frequency components are returned to a stage preceding the filter, which may cause unexpected oscillation in a circuit, for example. The absorption-type low-pass filter is a type of filter that absorbs unnecessary frequency components, and improves the above-mentioned disadvantages found in the reflection-type low-pass filter.

[0003] Absorption-type low-pass filters have already been proposed. One example using ferrite is
It is widely used as a laminated noise suppression component.

The laminated noise suppression component has a structure in which a conductor is embedded in a magnetic layer made of ferrite, and a ferrite paste and a conductor paste or metal foil are laminated by a printing technique or a thick film sheet laminating method. Obtained by:

[0005] As a conventional laminated noise suppression component, there is known a component using NiCuZn ferrite which can be sintered at a low temperature for the purpose of co-firing with Ag and an Ag alloy having low DC resistance. . However, NiCuZn ferrite has a dielectric constant of about 10 to 15, and the stray capacitance generated between conductor patterns increases. Therefore, the self-resonant frequency cannot be increased, and the use at high frequencies is limited.

As another example, Mn which is a high magnetic permeability material is used.
System, planar system suitable for high-frequency materials, etc.
Since the firing temperature is high and the firing atmosphere needs to be controlled, it is not suitable for simultaneous firing with a metal internal conductor.

Furthermore, in the case of a laminated noise suppression component in the form of a ferrite chip bead, the peak of the impedance is about 700 to 800 MHz even if a material having a low μ is used, and noise absorption in the GHz band cannot be performed. In addition, it is sufficient to increase the number of turns or use a high μ material to increase the impedance value, but the peak value shifts to a lower frequency side.

As another prior art, US Pat. No. 4,297,661 discloses a high-pass filter in which a microstrip is made of ferrite. This high-pass filter utilizes the phenomenon that the absorption action occurs on the low frequency side and the absorption action does not occur on the high frequency side.
Unnecessary signal components in the high frequency region described above cannot be suppressed by absorption.

[0009] Schiffres is an IEEE Trans Electron Magn.
Compt. EMC-6 55-61 1964 proposes a coaxial transmission line using ferrite. This coaxial transmission line is intended mainly for acquiring characteristics in the MHz band. It does not disclose transmission characteristics and reflection characteristics in a high frequency range. It is considered that transmission also occurs in a high frequency region of GHz or more.

An attempt has been made to combine a non-magnetic material having an absorption function on the high frequency side with ferrite to remove a signal by absorption on the high frequency side. Schlicke is IEEE S
EMI filter proposed in pectrum 59-68 1967, B
An example is the low-pass EMI filter proposed by Ogar in Proc. of IEEE 67 159-163 1979. In these prior arts, a part of the insulator of the coaxial filter is formed by laminating a ferrite and a dielectric. Fiallo also has a doctoral dissertation from Pennsylvania State University.
In 1993, a filter with a microstrip structure combining a ferrite and a dielectric was proposed. However, in these prior arts, a multilayer structure has to be adopted and the structure becomes complicated.

Next, US Pat. No. 4,146,854 discloses an attenuating element using a ferrite bead and a radio wave absorber made of a metal or resin composite member, and Japanese Patent Application Laid-Open No. 4-127701 discloses a damping element. A technique using a radio wave absorbing material for a part of a non-magnetic microstrip line is disclosed. However, in any case, the radio wave absorber or radio wave absorber
It is merely used as a supplement to suppress high-frequency components that cannot be absorbed.

Further, US Pat. No. 4,301,428 discloses an electric wire or cable containing a conductive element having an appropriate electric resistance and a magnetic absorbing mixture. The conductive element is
It has a composite structure in which a non-conductive core made of fiber, resin, glass, or the like is covered with a thin conductive metal layer. The magnetic absorbing mixture is non-conductive and coats the conductive element. However, providing a signal line with an electric resistance value not only removes noise components but also attenuates signal components. Therefore, there is a problem in applications handling small signals, for example. Further, this prior example discloses an electric wire, and does not describe an example as a circuit element.

JP-A-8-78218 discloses that an electrode for signal lines is provided inside an insulating base made of a composite member in which ferromagnetic metal powder and an insulating resin are mixed, and an electrode for grounding is provided on the surface of the insulating base. A high frequency chip bead element is disclosed. According to this high-frequency chip bead element, a high-frequency chip bead element having high-frequency blocking and low-pass characteristics capable of absorbing a high-frequency component of 1 GHz or more can be obtained. However, since the high-frequency chip bead element uses ferromagnetic metal powder, the high-frequency stop frequency characteristic is sharp, and is not suitable for expanding the stop frequency region.

[0014]

The problem to be solved by the present invention is
An object of the present invention is to provide a high-frequency chip bead element having high-frequency blocking and low-pass characteristics capable of reliably absorbing high-frequency components in a band.

Another object of the present invention is to provide a high-frequency chip bead element having an enlarged stop frequency region.

Still another object of the present invention is to provide a high-frequency chip bead element having a simple structure.

[0017]

In order to solve the above-mentioned problems, a high-frequency chip bead element according to the present invention includes an insulating base and at least one signal conductor. The insulating base is a composite member in which ferrite powder and an insulating resin are mixed. The signal conductor is spirally embedded inside the insulating base.

Since the insulating base is a composite member in which ferrite powder and insulating resin are mixed, unnecessary high-frequency components in a high-frequency region included in the frequency signal passing through the signal conductor can be reliably absorbed by the absorbing action of the insulating base. . In particular,
Absorption function in high frequency band of 1GHz or more (high-frequency rejection)
And a signal belonging to a lower frequency band is passed (low-pass) to form a high-frequency chip bead element. Therefore, the high-frequency chip bead element according to the present invention can be used as a low-pass filter.

Since this high-frequency chip bead element uses ferrite powder, the high-frequency cutoff frequency characteristic is broad. For this reason, compared with the case of using ferromagnetic metal powder,
The stop frequency range becomes wider.

In addition, the insulating base for absorbing high frequency components is a composite member in which ferrite powder and insulating resin are mixed,
Since the signal line electrode is helically embedded inside the insulating base, the structure is extremely simplified.

In the case of the composite member used in the present invention, although the magnetic permeability decreases with an increase in the frequency, the dielectric constant also decreases at the same time, which contributes to a reduction in the impedance change. The result is less reflection. Therefore, a low-pass filter that exhibits a high-frequency blocking effect by absorption in a high-frequency region can be realized, and a high-frequency chip bead element with less reflection can be obtained.

Moreover, Japanese Patent Application Laid-Open No. 8-78 using ferromagnetic metal powders
Unlike the technique disclosed in Japanese Patent Publication No. 218, the use of ferrite powder makes it possible to actively utilize the residual loss of ferrite powder and expand the frequency rejection region. Ferrite powder is a polycrystal, and generates residual loss over a wide frequency range as compared with ferromagnetic metal powder. The present invention effectively utilizes the characteristics of the ferrite powder.

[0023]

FIG. 1 is a sectional view of a high-frequency chip bead element according to the present invention, and FIG. 2 is a perspective view emphasizing a signal conductor included in the high-frequency chip bead element shown in FIG. The illustrated high-frequency chip bead element is an insulating substrate 1
And at least one signal conductor 2. The insulating base 1 is a composite member in which ferrite powder and an insulating resin are mixed. The signal conductor 2 is helically embedded inside the insulating base 1.

The insulating substrate 1 has a pair of terminal electrodes 51 and 52 for external connection at opposite ends. Therefore, it can be used as a surface mount chip component. Signal conductor 2
Is wound so as to be wound with an interval in a direction orthogonal to the direction in which the terminal conductors 51 and 52 are located. The interval between the turns may be at least the wire diameter of the wire constituting the signal conductor 2. Both ends of the signal conductor 2 are connected to the pair of terminal electrodes 51 and 52, respectively.

Since the insulating base 1 is a composite member in which ferrite powder and insulating resin are mixed, unnecessary high-frequency components in a high-frequency region included in a frequency signal passing through the signal conductor 2 are reliably absorbed by the insulating base 1. Can be absorbed. Specifically, an absorption effect (high-frequency rejection) is generated in a high-frequency band of 1 GHz or more, and a signal belonging to a lower frequency band is passed (low-pass). Therefore, the high-frequency chip bead element according to the present invention is:
Suitable for use as a low-pass filter.

Since this high-frequency chip bead element uses ferrite powder, the high-frequency rejection characteristic is broad. For this reason, compared with the case of using ferromagnetic metal powder,
A high frequency chip bead element having a wide stop frequency region can be obtained.

Moreover, the insulating substrate 1 that absorbs high frequency components
Is a composite member in which ferrite powder and an insulating resin are mixed, and the signal conductor 2 is helically embedded inside the insulating base 1, so that the structure is extremely simplified.

The high-frequency chip bead element according to the present invention comprises:
It utilizes the residual loss of the ferrite material and the low dielectric constant of the organic insulating resin. The low-pass and high-pass blocking mechanisms of the high-frequency chip bead element according to the present invention are as follows.

In the transmission line, the reflection gain S11 (ω)
And the transmission gain S21 (ω) are expressed by the following equation, where 反射 is the reflectance of the element and T is the transmittance.

S11 (ω) = (1−T^Two ) Γ / (1-T^TwoΓ^Two) S21 (ω) = (1 ー Γ^Two) T / (1-T^TwoΓ^Two) Γ = {(μ_eff/ ε_eff  )^1/2 ー Zo} / {(μ_eff/ ε_eff )^1/2 + Zo} T = exp {-iω (ε_effμ_eff)^1/2x}. Where ε_effIs the complex effective permittivity of the material,
μ_effIs the complex effective magnetic permeability of the material. Complex effective permittivity
ε_effAnd complex effective permeability μ_effIs actually the complex of the material
It is the dielectric constant and complex permeability with the shape factor added.
You. Zo is the characteristic impedance of the circuit.

First, in order to cause absorption in a high frequency region, the transmittance T must be close to zero. The condition is that (ε _eff μ _eff ) is imaginary or real and negative. That is, one or both of the imaginary components of ε _eff and μ _eff are present, and the larger the value, the greater the absorption in the transmission line. In other words, the loss angle (tan δ) of the material increases at high frequencies.

In order to reduce the reflection over all frequencies (reduce S11), the reflectance 反射 must be close to zero. Therefore, (μ _eff / ε _eff ) ^1/2 needs to be close to the characteristic impedance Zo over all frequencies.

On the other hand, the composite member used in the present invention absorbs remarkably from about 1 GHz, absorbs even at 20 GHz or more, and is accompanied by dielectric absorption.

In general, the real components of the dielectric constant ε and the magnetic permeability μ decrease with the frequency in a region where absorption occurs. Therefore, when there is absorption, the characteristic impedance Zo of the high-frequency chip bead element changes with the frequency, and as a result, the reflectance 反射 increases and the reflection becomes remarkable.

In the case of the composite member used in the present invention, although the magnetic permeability decreases with an increase in the frequency, the dielectric constant also decreases at the same time, contributing to a decrease in the impedance change. The result is less reflection. Therefore, a low-pass filter that exhibits a high-frequency blocking effect by absorption in a high-frequency region can be realized, and a high-frequency chip bead element with less reflection can be obtained.

The type of insulating resin mixed with ferrite powder is not particularly limited, but it has been confirmed that epoxy, phenol, rubber, acrylic or Teflon-based insulating resin can provide good properties. These insulating resins can be used alone or in combination. By using these resins, the conventional high temperature (about 90%) can be obtained.
Since the product can be obtained at a low temperature of 100 ° C. to 200 ° C. instead of 0 ° C.), the insulating substrate 1 can be easily manufactured irrespective of the limitation of the firing temperature and the firing atmosphere.

Various materials can be used as the ferrite powder contained in the insulating base 1. For example, Ni-C
Ferrite materials such as u-Zn, Mn-Zn, Mn-Mg-Zn, and Ni-Zn can be exemplified. The amount of the insulating resin is preferably in the range of 5 to 90 parts by weight based on the weight of the ferrite powder.

By changing the content of the ferrite powder within this range, μ and ε of the insulating base 1 can be arbitrarily changed, and the high frequency noise absorption characteristics can be easily designed.

If the content of the insulating resin with respect to the ferrite powder is more than 90 parts by weight, sufficient attenuation cannot be obtained. In addition, the content of the insulating resin with respect to the ferrite powder is 5%.
If the amount is less than the weight part, it becomes difficult to uniformly mix with the resin, and the strength of the component is reduced, and the insulation resistance between the electrodes is significantly deteriorated.

The high-frequency chip bead elements shown in FIGS. 1 and 2 are prepared by combining a paint or a thick film sheet obtained by mixing ferrite powder and an insulating resin with a conductive paste or a metal foil by a printing technique or a thick film sheet laminating method. It can be obtained by laminating. For this reason, it becomes extremely excellent in mass productivity.

FIG. 3 is an electrical equivalent circuit diagram of the high-frequency chip bead element according to the present invention. As shown in FIG.
The high-frequency chip bead element shown in FIG.
An equivalent circuit is obtained by inserting a line inductance L generated by the signal conductor 2 into 1-52.

Since the magnetic loss of the high-frequency chip bead element expressed by the circuit of FIG. 3 is proportional to the line inductance L, in a frequency band where the line impedance L is equal to or higher than the output impedance of the drive circuit (not shown)
The loss increases and the characteristics are equivalent to those of a low-pass filter. However, unlike a low-pass filter composed of ordinary low-loss circuit elements, in the attenuation band, signal energy is absorbed in the element and is not reflected. in this way,
By embedding the signal conductor 2 inside the insulating base 1 containing ferrite powder having a small particle diameter, a high-frequency chip bead element that exhibits a large magnetic loss at a wide frequency and absorbs unnecessary frequency components is realized. it can.

Next, Table 1 shows the impedance peak value and the frequency at that time for Comparative Examples 1 and 2 obtained by changing the composition of the insulating substrate 1 and Examples 1 to 6. In Comparative Examples 1 and 2, the signal conductor was embedded inside the ferrite.

From the results shown in Table 1, in Comparative Examples 1 and 2 using only an NiCuZn ferrite and no resin-containing insulating substrate, the impedance was about 700 MHz. In contrast to the occurrence of a peak, in Examples 1 to 6 using an insulating substrate made of a composite of NiCuZn ferrite and a resin, 1
It can be seen that an impedance peak occurs in a high frequency band of GHz or more.

FIG. 4 is a diagram showing the electromagnetic characteristics of Comparative Example 1 and Example 6 in comparison. As shown in FIG.
Indicates a characteristic in which an impedance peak occurs at a frequency of about 700 MHz. Example 6 shows a characteristic in which an impedance peak occurs at a frequency of about 3 GHz. From this result, it can be seen that the resin-ferrite composite member has a higher stop frequency range than the ferrite sintered body.

FIG. 5 shows the electromagnetic characteristics L2 of chip beads prepared using carbonyl iron, which is a magnetic metal powder, and Ni and Ni.
FIG. 4 is a diagram showing a comparison of electromagnetic characteristics of chip beads made using CuZn-based ferrite. In FIG. 5, the horizontal axis represents frequency, and the vertical axis represents impedance value | Z |. As shown in FIG. 5, by using a ferrite material, noise can be cut in a wider frequency band than when magnetic metal powder is used. This means that the chip beads according to the present invention using ferrite powder, unlike the technique disclosed in JP-A-8-78218 using ferromagnetic metal powder, actively utilize the residual loss of ferrite powder. Means that the frequency rejection region can be expanded.
Ferrite powder is a polycrystal, and generates residual loss over a wide frequency range as compared with ferromagnetic metal powder.
The present invention effectively utilizes the characteristics of the ferrite powder.

Furthermore, compared to magnetic metal powders such as carbonyl iron, ferrite materials have the advantage that ferrites and ferrite compositions can be selected in a wider range, and magnetic characteristics can be designed in a wider range as required.

Further, in the case of a composite material in which a magnetic metal powder (carbonyl iron) and a resin are mixed (Japanese Unexamined Patent Publication No. 8-78218), the surface of the carbonyl iron is oxidized in order to secure insulation. A high resistance film must be formed. On the other hand, in the case of the present invention using ferrite, such a pretreatment is not required, so that the manufacturing process can be shortened.

FIG. 6 is a sectional view showing another embodiment of the high-frequency chip bead element according to the present invention. In the figure, FIG.
3 are denoted by the same reference numerals, and detailed description thereof will be omitted. The high-frequency chip bead element shown in FIG. 6 is embedded in the insulating base 1 so that the signal conductor 2 turns in the direction in which the terminal conductors 51 and 52 exist. As described above, the insulating base 1 is a composite member in which ferrite powder and an insulating resin are mixed.

[0050]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a high-frequency chip bead element having high-frequency blocking and low-pass characteristics capable of reliably absorbing high-frequency components in a high-frequency region. (B) It is possible to provide a high-frequency chip bead element having high-frequency rejection and low-pass characteristics capable of reliably absorbing high-frequency components of 1 GHz or more. (C) It is possible to provide a high-frequency chip bead element having an expanded element frequency range. (D) A high-frequency chip bead element having a simple structure can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a high-frequency chip bead element according to the present invention.

FIG. 2 is a perspective view in which signal conductors included in the high-frequency chip bead element shown in FIG. 1 are emphasized.

FIG. 3 is an electrical equivalent circuit diagram of the high-frequency chip bead element shown in FIGS. 1 and 2;

FIG. 4 is a diagram showing a comparison between electromagnetic characteristics of Comparative Example 1 and Example 6 of the present invention.

FIG. 5 is a diagram showing a comparison between electromagnetic characteristics of carbonyl iron, which is a magnetic metal powder, and ferrite.

FIG. 6 is a sectional view of another embodiment of the high-frequency chip bead element according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating base 2 Signal conductor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Minoru Takaya 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation

Claims (8)

[Claims] 1. A high-frequency chip bead element including an insulating base and at least one signal conductor, wherein the insulating base is a composite member obtained by mixing ferrite powder and an insulating resin. A high-frequency chip bead element embedded spirally inside an insulating substrate. 2. The high-frequency chip bead element according to claim 1, wherein the high-frequency chip bead element is used as a low-pass filter. 3. The high-frequency chip bead element according to claim 2, wherein the high-frequency chip bead element has a noise absorption characteristic in a GHz band. 4. The high-frequency chip bead element according to claim 1, wherein the content of the insulating resin is in a range of 5 parts by weight to 90 parts by weight with respect to the weight of the ferrite powder. . 5. The high-frequency chip bead element according to claim 1, wherein the insulating resin is at least one of epoxy, phenol, rubber, acrylic, and Teflon. 6. The high-frequency chip bead element according to claim 1, wherein the insulating base has a pair of external connection terminal conductors at opposite ends, and both ends of the signal conductor are external. High-frequency chip bead elements connected to the connection terminal conductors. 7. The high-frequency chip bead element according to claim 6, wherein the signal conductor is wound so as to wind in a direction orthogonal to a direction in which the terminal conductor is present. 8. The high frequency chip bead element according to claim 7, wherein a paint or a thick film sheet in which ferrite powder and an insulating resin are mixed, and a conductive paste or a metal foil are printed by a printing technique or a thick film sheet laminating method. A high-frequency chip bead element obtained by laminating by means such as.