JP4912338B2 - Multilayer dielectric filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer dielectric filter which has sufficient attenuation quantity of an inhibition band and is excellent in signal selectivity. <P>SOLUTION: The multilayer dielectric filter 10 includes: a multilayer body 1 formed by stacking a plurality of dielectric layers 1a-1m; input-output terminal electrodes 3, 4 and a ground terminal electrode 2 attached on the external surface of the multilayer body 1; coil conductors 5, 6 arranged between the dielectric layers in the inside of the multilayer body 1 and each having one end electrically connected to the input-output terminal electrodes 3, 4; and annular ground conductors 7 arranged on the external peripheral edge in a region where the coil conductors 5, 6 are arranged when viewed in a stacking direction between dielectric layers 1a-1b and 1l-1m positioned above and below the coil conductors 5, 6 in the stacking direction inside the multilayer body 1, and having one end electrically connected to the ground terminal electrode 2. This dielectric filter has small capacity between a ground potential and the coil conductors 5, 6 and is utilized as a digital signal circuit, and an electromagnetic noise is sufficiently removed by the annular ground conductors 7. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a multilayer dielectric filter used for high-frequency noise removal or removal of harmonic components in an RF circuit block.

  As a conventional multilayer dielectric filter, for example, a multilayer body in which a plurality of dielectric layers are stacked, an input / output terminal electrode and a ground terminal electrode that are attached to the outer surface of the multilayer body, and the interior of the multilayer body There is known a multilayer dielectric filter having a coil conductor disposed between dielectric layers and having one end electrically connected to an input / output terminal electrode (see, for example, Patent Document 1).

Such a conventional multilayer dielectric filter can attenuate the high-frequency component of the electrical signal input from the input / output terminal electrode to the inside of the multilayer body by the inductance of the coil conductor, so that the high-frequency component included in the electrical signal can be attenuated. It has a function as a filter used for removing noise or removing harmonic components in the RF circuit block.
JP 2004-229268 A

  However, in the conventional multilayer dielectric filter described above, for example, electromagnetic noise may enter from the main surface side of the multilayer body, and in this case, signals input from the input / output terminal electrodes to the inside of the multilayer body may be used. Therefore, there is a problem in that electromagnetic wave noise cannot be sufficiently removed because the high frequency component attenuation effect using the entire coil conductor cannot be obtained.

  As a means for preventing electromagnetic wave noise entering from the main surface side of the multilayer body, there is a method in which ground conductors are arranged in substantially the entire area between dielectric layers positioned above and below the coil conductor in the lamination direction in the multilayer body. However, when this means is used, a large capacitance is generated between the coil conductor and the ground conductor, so that it takes a long time to accumulate charges, and the steepness of the waveform of the digital signal is deteriorated. There was a problem.

  The present invention has been devised in view of the problems in the conventional multilayer dielectric filter as described above, and its purpose is to sufficiently remove electromagnetic noise from the outside and to use it in a digital signal circuit. It is an object of the present invention to provide a possible multilayer dielectric filter.

The multilayer dielectric filter of the present invention includes a multilayer body formed by laminating a plurality of dielectric layers, an input / output terminal electrode and a ground terminal electrode that are attached to the outer surface of the multilayer body, and an interior of the multilayer body. A coil conductor, one end of which is electrically connected to the input / output terminal electrode, and a dielectric layer positioned above and below the coil conductor in the stacking direction inside the stack. disposed on the outer peripheral edge portion in the region where the coil conductors are arranged when viewed in the direction and comprising an annular ground conductor whose one end is connected the ground terminal electrodes electrically, the entering the output electrode is deposited from the side surface of the laminate toward both principal surfaces, in which a part is characterized that you have to face the annular ground conductor sandwiching the dielectric layer.

  According to the multilayer dielectric filter of the present invention, outside the region in which the coil conductor is disposed when viewed in the stacking direction between the dielectric layers located above and below the coil conductor in the stacking direction in the stack. Since the annular ground conductor, one end of which is electrically connected to the ground terminal electrode, is disposed at the peripheral portion, the annular ground conductor blocks and removes electromagnetic noise from entering the main surface of the laminate. In addition, since the capacitance generated between the annular ground conductor and the coil conductor is small, it can be used for a digital signal circuit without deteriorating the steepness of the waveform of the digital signal. Become. In addition, by creating a frequency band that greatly attenuates using the series resonance obtained by this slightly generated capacitance and the inductance generated by being formed in an annular shape, the impedance at the boundary between the passband and stopband Since the change can be made steep, it is possible to provide a multilayer dielectric filter with improved frequency band selectivity. Furthermore, since the annular ground conductor is annular, current flows in a direction around the annular ground conductor so as to generate an inductance that prevents electromagnetic waves generated by the inductance of the coil conductor from leaking to the outside. There is also an effect that a multilayer dielectric filter with less electromagnetic waves to the outside is obtained.

  Further, according to the multilayer dielectric filter of the present invention, the input / output terminal electrodes are attached from the side surface of the multilayer body to both main surfaces, and a part thereof faces the annular ground conductor with the dielectric layer interposed therebetween. Since a capacitance can be generated between the input / output terminal electrode and the annular ground conductor, it is possible to adjust the impedance between the input / output terminal electrode and the coil conductor using this capacitance. Become.

  Hereinafter, the multilayer dielectric filter of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an external perspective view showing an example of an embodiment of a multilayer dielectric filter of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is an exploded view of the multilayer body in FIG. It is a perspective view. The multilayer dielectric filter 10 of the present invention shown in these drawings includes, as a basic configuration, a multilayer body 1, input / output terminal electrodes 3 and 4 attached to the outer surface of the multilayer body 1, and a ground terminal electrode. 2, coil conductors 5 and 6 disposed inside the laminated body 1, and an annular ground conductor 7.

  Such a multilayer dielectric filter 10 is used, for example, for high-frequency noise removal or harmonic component removal in an RF circuit block. For example, an electric current input from the input / output terminal electrode 3 to the coil conductor 5 is used. It has an impedance characteristic that attenuates the high-frequency component of the electric signal before the signal is output from the input / output terminal electrode 4.

The laminated body 1 is a rectangular parallelepiped dielectric block in which a plurality of rectangular dielectric layers 1a to 1m are laminated. The dielectric layers 1a to 1m are formed by a dielectric material mainly composed of TiO ₂ —Nd ₂ O ₃ —BaTiO ₃ or the like with a thickness of 5 μm to 300 μm per layer.

  The input / output terminal electrode 3 is mainly composed of, for example, Cu, Ag, or an Ag-based alloy at a plurality of locations on one first side surface w of the pair of side surfaces in the longitudinal direction of the stacked body 1 in the stacking direction. A conductive material is used to form a belt with a thickness of 10 μm to 70 μm. In addition, on the second side surface 1x facing the first side surface 1w of the multilayer body 1, a plurality of input / output terminal electrodes 4 are formed at the positions facing the input / output terminal electrodes 3 with the same material and the same thickness as the input / output terminal electrodes 3. It is applied in a strip shape in the stacking direction.

  Further, the ground terminal electrode 2 is provided on each of the third side surface 1y and the fourth side surface 1z different from the first side surface 1w and the second side surface 1x of the multilayer body 1 on which the input / output terminal electrodes 3 and 4 are respectively formed. The same material and the same thickness as the input / output terminal electrodes 3 and 4 are applied in the stacking direction. Note that the area per ground terminal electrode 2 is larger than that of the input / output terminal electrodes 3 and 4, thereby making the ground potential easy to stabilize.

  The input / output terminal electrodes 3 and 4 and the ground terminal electrode 2 are mounting connection terminals to which solder or the like is bonded when the multilayer dielectric filter 10 is mounted on an external circuit board or the like. The input / output terminal electrodes 3 and 4 and the ground terminal electrode 2 are attached in a continuous and integral shape from each side surface of the multilayer body 1 to a part of both main surfaces, and the area to which the solder adheres To increase the mountability.

  The coil conductor 5 includes coil pattern conductors 5a to 5d, which are internal conductors formed in the dielectric layers 1b-1c, 1c-1d, 1d-1e, and 1e-1f, respectively, and a dielectric between the coil pattern conductors 5a to 5d. It is formed by sequentially connecting through through conductors indicated by broken lines formed in the body layers 1c to 1e. In addition, the coil conductor 6 includes coil pattern conductors 6a to 6d, which are internal conductors formed in the dielectric layers 1h-1i, 1i-1j, 1j-1k, and 1k-1l, between the coil pattern conductors 6a to 6d. The dielectric layers 1i to 1k are formed by sequentially connecting through through conductors indicated by broken lines.

  Further, one end of the coil conductor 5 is drawn out to the first side face 1 w on the upper side of the multilayer body 1 and is electrically connected to the input / output terminal electrode 3, and the other end is drawn out to the second side face 1 x on the upper side of the multilayer body 1. Thus, the input / output terminal electrode 4 is electrically connected. Further, one end of the coil conductor 6 is drawn out to the first side surface 1w at the lower side of the multilayer body 1 and is electrically connected to the input / output terminal electrode 3, and the other end is disposed at the lower side of the multilayer body 1 at the second side surface 1x. To the input / output terminal electrode 4. Further, the coil conductor 5 and the coil conductor 6 are alternately drawn out to the first side surface 1w and the second side surface 1x, respectively. The coil conductor 5 and the coil conductor 6 have a function as a filter capable of attenuating a high-frequency component of an electric signal input from the input / output terminal electrodes 3 and 4 into the multilayer body 1 by the inductance of the coil conductor 5 and the coil conductor 6. Yes.

  As described above, the multilayer dielectric filter 10 of this example includes the input / output terminal electrodes 3 and 4 that are alternately formed on the first side surface 1w and the second side surface 1x, which are side surfaces in the longitudinal direction of the multilayer body 1, respectively. The separate coil conductors 5 and 6 configured inside the multilayer body 1 are electrically connected to each other to form a multi-layered multilayer dielectric filter having a plurality of independent filter functions. ing.

  Each of the dielectric layers 1f-1g and 1g-1h is formed with an internal conductor ground conductor 9 having an area that occupies most of the respective dielectric layers 1f-1g and 1g-1h, and a part thereof is a laminate. The first side surface 1y and the fourth side surface 1z are drawn out and electrically connected to the ground terminal electrode 2, and a portion where the coil conductor 5 is formed and a portion where the coil conductor 6 is formed in the stacking direction. By being arranged between them, the capacitive coupling between the coil conductor 5 and the coil conductor 6 is prevented. Further, since the ground conductor 9 is formed between the two dielectric layers 1f-1g and 1g-1h, the ground potential of each ground conductor 9 varies less.

  The internal conductors such as the coil conductors 5 and 6 and the ground conductor 9 are formed with a thickness of 10 μm to 70 μm using, for example, a conductor material mainly composed of Cu, Au, or an Ag-based alloy. In addition, the through conductor is formed in a cylindrical shape having a diameter of 30 to 300 μm using, for example, the same material as the internal wiring conductor.

  In the multilayer dielectric filter 10 of this example, the annular ground of the inner conductor is placed between the dielectric layers 1a-1b and 11-1m located above and below the coil conductors 5 and 6 in the stacking direction in the multilayer body 1. Conductors 7 are respectively disposed. Further, the annular ground conductor 7 disposed in the dielectric layer 1a-1b is disposed at the outer peripheral edge in the region where the coil conductor 5 is disposed when viewed in the stacking direction. The annular ground conductor 7 disposed at 1 m is disposed at the outer peripheral edge in the region where the coil conductor 6 is disposed when viewed in the stacking direction. Further, one end of each annular ground conductor 7 is drawn out to the third side surface 1 y and the fourth side surface 1 z of the multilayer body 1 and is electrically connected to the ground terminal electrode 2.

  As described above, according to the multilayer dielectric filter 10 of this example, the dielectric layer 1a-1b, 11-1m located above and below the coil conductors 5 and 6 in the stacking direction in the stack 1 is stacked in the stacking direction. Since an annular ground conductor 7 having one end electrically connected to the ground terminal electrode 2 is disposed at the outer peripheral edge in the region where the coil conductors 5 and 6 are disposed when viewed in FIG. The ground conductor 7 has an effect of blocking and removing the intrusion of electromagnetic wave noise from the main surface side of the multilayer body 1, and the capacitance generated between the annular ground conductor 7 and the coil conductors 5 and 6. Therefore, the steepness of the waveform of the digital signal is not deteriorated, and the digital signal circuit can be used. Further, a pass band and a stop band are created by creating a frequency band that is greatly attenuated by using a series resonance obtained by the slightly generated capacitance and the inductance generated by forming the annular ground conductor 7 in an annular shape. Therefore, the multilayer dielectric filter 10 with enhanced frequency band selectivity can be obtained. Furthermore, since the annular ground conductor 7 is annular, current flows in a direction around the annular ground conductor 7 so that an inductance is generated in a direction that prevents electromagnetic waves generated by the inductance of the coil conductors 5 and 6 from leaking to the outside. As a result, the effect of the multilayer dielectric filter 10 with less electromagnetic waves to the outside can be obtained.

  In the multilayer dielectric filter 10 of this example, ground coil pattern conductors 8a to 8c as internal conductors are formed in the dielectric layers 1c-1d, 1d-1e, and 1e-1f, and each ground coil is formed. A ground coil conductor 8 is formed by sequentially connecting through through conductors indicated by broken lines formed in the dielectric layers 1d and 1e between the pattern conductors 8a to 8c. The ground coil conductor 8 is electrically connected to the ground conductor 9 at one end via a through conductor formed on the dielectric layer 1f, and the other end is open. A part of the ground coil pattern conductor 8b constituting the ground coil conductor 8 is opposed to the coil pattern conductors 5b and 5d to generate a capacitance. The capacitance and the inductance of the ground coil conductor 8 cause series resonance. Therefore, the multilayer dielectric filter 10 having a frequency band that greatly attenuates due to the frequency band selectivity is thereby obtained.

  In addition, ground coil pattern conductors 12a to 12c as internal conductors are formed in the dielectric layers 1h-1i, 1i-1j, and 1j-1k, respectively, and the dielectric layers 1i and 12c between the ground coil pattern conductors 12a to 12c are formed. A ground coil conductor 12 is formed by sequentially connecting through conductors indicated by broken lines formed in 1j. The ground coil conductor 12 is electrically connected to the ground conductor 9 at one end via a through conductor formed in the dielectric layer 1h, and the other end is open. The ground coil conductor 12 also has the effect of further improving the selectivity of the frequency band of the multilayer dielectric filter 10 as with the ground coil conductor 8. Specifically, a part of the ground coil pattern conductor 12b constituting the ground coil conductor 12 is opposed to the coil pattern conductors 6a and 6b to generate a capacitance, and this capacitance and the inductance of the ground coil conductor 12 are connected in series. By resonating, a frequency band that greatly attenuates is created.

  The multilayer dielectric filter 10 of this example is manufactured by the following method, for example.

  The method of manufacturing the multilayer dielectric filter 10 of this example basically includes a multilayer sheet formed by laminating a plurality of dielectric green sheets having a pattern of a conductor paste corresponding to a predetermined inner conductor and through conductor. A first step to be produced, a second step in which the laminated sheet is cut into a plurality of rectangular parallelepiped pieces, and the individual laminated sheets are sintered by firing to have each internal conductor and through conductor. A third step of producing the rectangular parallelepiped laminate 1 and a fourth step of forming the input / output terminal electrodes 3 and 4 and the ground terminal electrode 2 by applying and baking a conductor paste on the side surface of the laminate 1 are provided.

In the first step, the dielectric green sheet is prepared by adding a suitable organic solvent and organic binder to a metal oxide powder such as BaTiO ₃ , TiO _2, and Nd ₂ O ₃ and mixing them. The dielectric ceramic slurry is produced by forming the dielectric ceramic slurry into a predetermined shape and a predetermined thickness by, for example, a doctor blade method. The conductor paste is prepared, for example, by adding an appropriate organic solvent, an organic binder, and the like to a powder of a conductor material mainly composed of Cu, Ag, or an Ag-based alloy. The pattern of the conductor paste corresponding to the internal conductor is formed by applying it in a predetermined shape and a predetermined thickness by, for example, screen printing. For the pattern of the conductor paste corresponding to the through conductor, for example, a through hole is formed by punching a predetermined portion of the dielectric green sheet using a mold or the like, and the conductor paste is filled into the through hole by a screen printing method or the like. Formed by.

  And the laminated sheet is produced by laminating and adhering the dielectric green sheets on which the above-mentioned pattern of the conductive paste is formed.

  In the second step, the laminated sheet is cut into a plurality of pieces by cutting, for example, using a cutting blade along the boundary line of the pieces corresponding to the plurality of laminated dielectric filters 10 arranged vertically and horizontally. To separate.

  In the third step, the firing temperature is set to a maximum temperature of 930 ° C. to 970 ° C., for example, when using the above-described materials.

  In the fourth step, the conductive paste for forming the input / output terminal electrodes 3 and 4 and the ground terminal electrode 2 is prepared by adding an appropriate organic solvent, organic binder, or the like to the powder of the conductive material mainly composed of Cu, Ag, or an Ag-based alloy. It is prepared by adding and mixing. The surfaces of the input / output terminal electrodes 3 and 4 and the ground terminal electrode 2 are preferably formed by plating a metal film such as Ni or Sn as a plating film.

  Further, according to the multilayer dielectric filter 10 of this example, as shown in FIG. 2, the input / output terminal electrodes 3 and 4 are deposited from the side surface of the multilayer body 1 to both main surfaces. Part of the output terminal electrodes 3, 4 faces the annular ground conductor 7 with the dielectric layer 1a interposed therebetween, and part of the input / output terminal electrodes 3, 4 faces the annular ground conductor 7 with the dielectric layer 1m interposed therebetween. ing. As a result, a capacitance can be generated between the input / output terminal electrodes 3 and 4 and the annular ground conductor 7, so that the impedance between the input / output terminal electrodes 3 and 4 and the coil conductors 5 and 6 is adjusted. Is possible.

  The present invention is not limited to the embodiments described above, and various changes and improvements can be made without departing from the scope of the present invention.

  For example, in the example of the embodiment described above, the input / output terminal electrode 3 is on the electric signal input side and the input / output terminal electrode 4 is on the electric signal output side. Thus, any one of the input / output terminal electrodes 3 and 4 may be an input side of an electric signal, and any of them may be an output side.

  Further, in the example of the embodiment described above, the multilayer dielectric filter 10 is a multi-layered multilayer dielectric filter 10 having a plurality of filter functions, but is not limited to such a configuration. It is also possible to have only one filter function.

  Further, the ground conductor 9 for preventing the capacitive coupling between the coil conductor 5 and the coil conductor 6 is formed between the two dielectric layers, but the ground conductor 9 is formed only between the one dielectric layer. It may also be formed, or may be formed between three or more dielectric layers.

  Further, although the coil conductors 5 and 6 are separately disposed above and below the laminated body 1 with the ground conductor 9 interposed therebetween, the coil conductors 5 and 6 may be disposed side by side without forming the ground conductor 9. Good.

  A specific example of the multilayer dielectric filter of the present invention will be described.

As a sample 1, the multilayer dielectric filter 10 of the present invention was produced. The sample 1 has a rectangular parallelepiped shape with a length of 2.0 mm, a width of 1.25 mm, and a height of 0.8 mm, and the input / output terminal electrode 3 as shown in FIGS. 4, a ground terminal electrode 2, an inner conductor and a through conductor, and a multi-layered laminated dielectric filter having four filter circuits. The material constituting the sample 1 is a material whose main component is TiO ₂ —Nd ₂ O ₃ —BaTiO ₃ for the dielectric material, and a material whose main component is Ag for the material of the internal conductor and the through conductor. .

  As Sample 2, a multilayer dielectric filter of a comparative example was produced. Sample 2 has the same shape and material as Sample 1 except that the annular ground conductor 7 of the multilayer dielectric filter 10 of the present invention is not formed.

  For these samples 1 and 2, when the waveform of the digital signal was examined using an oscilloscope, the sharpness of the signal waveform was greatly degraded for sample 2, but the sharpness of the signal waveform was degraded for sample 1. It was hardly seen. This has the effect that the annular ground conductor 7 blocks and removes the intrusion of electromagnetic wave noise from the main surface side of the multilayer body 1, and the capacitance generated between the annular ground conductor 7 and the coil conductor 5 is small. This is because the steepness of the waveform of the digital signal is not deteriorated.

  Further, with respect to Samples 1 and 2, a result of measuring a signal output from the input / output terminal electrode 4 when a signal of a certain level is input from the input / output terminal electrode 3 to the coil conductor 5 in the frequency band of 0 to 3 GHz. Is shown in FIG. FIG. 4 is a diagram showing the attenuation characteristics of the multilayer dielectric filter. The horizontal axis indicates the frequency (unit: Hz) of the output signal, and the vertical axis indicates the attenuation amount (unit: dB) of the output signal. Indicates. A solid characteristic curve X in the figure shows the attenuation characteristic of the sample 1, and a broken characteristic curve Y shows the attenuation characteristic of the sample 2.

  As can be seen from the results shown in FIG. 4, the sample 1 has a larger attenuation in the entire frequency band of 500 to 2500 MHz than the sample 2, and particularly, the attenuation in the vicinity of the frequency band 500 MHz near the boundary with the pass band is large. It has become. This is because a large amount of attenuation is obtained by series resonance between the inductance of the annular ground conductor 7 and the capacitance between the annular ground conductor 7 and the coil conductor 5.

  As described above, according to the multilayer dielectric filter of the present invention, the region in which the coil conductor is disposed when viewed in the stacking direction between the dielectric layers positioned above and below the coil conductor in the stacking direction within the stack. Since an annular ground conductor, one end of which is electrically connected to the ground terminal electrode, is disposed on the outer peripheral edge of the inside, the intrusion of electromagnetic wave noise from the main surface side of the laminate is blocked, and the digital signal It was confirmed that a sharply damped frequency band could be created without degrading the steepness of the waveform.

It is an external appearance perspective view which shows an example of embodiment of the laminated dielectric filter of this invention. It is the sectional view on the AA line of the laminated body of FIG. It is a disassembled perspective view of the laminated body of FIG. It is a diagram which shows the attenuation | damping characteristic of a laminated dielectric filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laminated body 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j, 1k, 1l, 1m ... Dielectric layer 1w ... 1st side surface 1x ... 2nd Side surface 1y ... Third side surface 1z ... Fourth side surface 2 ... Ground terminal electrode 3, 4 ... Input / output terminal electrode 5, 6 ... Coil conductor 5a, 5b, 5c, 5d, 6a, 6b, 6c, 6d ... coil pattern conductor 7 ... annular ground conductor 8, 12 ... ground coil conductor 9 ... ground conductor
10 ... Multilayer dielectric filter

Claims (1)

A laminate in which a plurality of dielectric layers are laminated;
An input / output terminal electrode and a ground terminal electrode applied to the outer surface of the laminate;
A coil conductor disposed between the dielectric layers inside the laminate and having one end electrically connected to the input / output terminal electrode;
Between the dielectric layers located above and below the coil conductor in the laminating direction in the laminating body, disposed at the outer peripheral edge portion in the region where the coil conductor is disposed when viewed in the laminating direction, one end of the laminated body An annular ground conductor electrically connected to the ground terminal electrode ;
The input-output terminal electrodes is deposited from the side surface of the laminate toward both main surfaces, the laminated dielectric partially characterized that you have to face the annular ground conductor sandwiching the dielectric layer Body filter.

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