JP6511741B2 - Impedance conversion element and method of manufacturing the same - Google Patents

Description

  The present invention relates to an impedance conversion element applied to an antenna device or the like and a method of manufacturing the same.

  In recent years, communication terminal devices such as mobile phones are required to be compatible with a wide variety of communication systems. The antenna device in such a communication terminal device needs to cover a wide frequency band of, for example, 800 MHz to 2.4 GHz.

  For example, Patent Document 1 is disclosed as an antenna device corresponding to a wide frequency band. FIGS. 10A and 10B are examples of circuit diagrams of the antenna device shown in Patent Document 1. FIG. FIG. 10 (A) is a circuit diagram schematically represented, and FIG. 10 (B) is a circuit diagram represented in consideration of a laminated structure when the impedance conversion circuit 25 in FIG. 10 (A) is formed of a multilayer substrate. is there. As shown in FIG. 10B, the impedance conversion circuit 25 of this antenna device includes a primary coil formed of conductor patterns L1A, L1B, L1C, and L1D, and a secondary coil formed of conductor patterns L2A and L2B. FIG. 11 is a view showing an example of the conductor pattern of each layer when the impedance conversion circuit 25 shown in FIG. 10 (B) is formed in a multilayer substrate. The conductor patterns L1A, L1B, L1C, L1D, L2A, and L2B are formed in a plurality of dielectric layers, and predetermined positions of these conductor patterns are interlayer-connected by a large number of via conductors.

International Publication No. 2014/050552

  In general, in high frequency transformers, characteristics regarding insertion loss, self-resonance frequency and coupling coefficient are important. In an impedance conversion circuit of a transformer structure configured by a multilayer substrate as shown in FIG. 11, the insertion loss, the self-resonance frequency and the coupling coefficient are in a trade-off relationship with each other. For example, if the line width of the conductor pattern is increased in order to reduce the conductor loss for the purpose of improving the insertion loss, the interlayer capacitance is increased. As a result, the self resonance frequency is lowered. Further, if the line width of the conductor pattern is increased, the coil inner diameter is decreased, and the coupling coefficient is reduced. In addition, in order to increase the self-resonance frequency, if the distance between the conductor patterns is increased to reduce the capacitance between the primary coil and the secondary coil, the coupling coefficient between the primary coil and the secondary coil becomes descend. In addition, in order to increase the coil opening by narrowing the line width of the conductor pattern in order to increase the coupling coefficient, the insertion loss increases. Furthermore, when trying to adjust the inductance value and the capacitance value by the line width of the conductor pattern, the inductance value and the capacitance value have a trade-off relationship. Since the self-resonant frequency is determined by 1 / (2π ((LC)), the self-resonant frequency can not be increased unless the inductance value and the capacitance value can be reduced separately.

  An object of the present invention is to solve the trade-off relationship between insertion loss, self-resonance frequency and coupling coefficient, and to provide an impedance conversion element in which these characteristics are set to predetermined values, and a method of manufacturing the same.

(1) The impedance conversion element of the present invention is
A first coil element and a second coil element connected in series and transformer-coupled to a laminated element body formed by laminating a plurality of base material layers,
The first coil element is composed of a plurality of conductor patterns provided on different layers of the multilayer body,
The second coil element is composed of a plurality of conductor patterns provided on different layers of the multilayer body,
It said first guide that make up the coil element body pattern and the conductive material pattern that make up the second coil element is the same is approximate shape in plan view from the stacking direction,
An air gap layer is formed between the conductor pattern of the first coil element and the conductor pattern of the second coil element.

  According to the above configuration, it is possible to suppress the interlayer capacitance between the conductor pattern forming the first coil element and the conductor pattern forming the second coil element. That is, the capacitance component can be reduced without changing the conductor pattern of each layer or the interlayer distance (the distance between the conductor patterns in the thickness direction). This can increase the self-resonant frequency without increasing the insertion loss and without reducing the coupling coefficient.

(2) The air gap layer is a first air gap layer formed on the surface of the conductor pattern of the first coil element facing the conductor pattern of the second coil element, and the first of the conductor pattern of the second coil element A second air gap layer formed on the surface facing the conductor pattern of the coil element, wherein the one or more base material layers are disposed between the first air gap layer and the second air gap layer Is preferred.
( 3 ) The air gap layer is a surface of the conductor pattern of the first coil element facing the conductor pattern of the second coil element, or a surface of the conductor pattern of the second coil element facing the conductor pattern of the first coil element have been made form, it is preferred that not formed between the conductor patterns forming the conductor pattern constituting the first coil element of the first coil element. With this configuration, the inter-layer capacitance between the first coil element and the second coil element can be suppressed with a small number of air gap layers.

( 4 ) If the line width of the air gap layer is made larger than the line width of the conductor pattern, the effective dielectric constant between the first coil element and the second coil element is effectively reduced, and the first coil element The inter-layer capacitance between the second coil element and the second coil element can be further suppressed.

( 5 ) If the line width of the air gap layer is made smaller than the line width of the conductor pattern, the surface area of the conductor pattern becomes larger (the sectional contour becomes longer) due to the deformation of the conductor pattern, and the insertion loss can be reduced.

( 6 ) The manufacturing method of the impedance conversion element of the present invention is
What is claimed is: 1. A method of manufacturing an impedance conversion element comprising a first coil element and a second coil element connected in series and transformer coupled to a laminated element formed by laminating a plurality of base material layers,
Forming a conductive paste pattern of the first coil element by coating on the first surface of the first base layer among the plurality of base layers, and applying a paste pattern for forming a void layer on the surface of the conductive paste pattern When,
A paste pattern for void layer formation is applied and formed on the first surface of the second base material layer among the plurality of base material layers, and a conductor paste pattern of a second coil element is applied on the surface of the void pattern for paste layer formation. The process to
Forming a laminate by overlapping and laminating the first surface of the first base layer on the second surface of the second base layer;
Baking the plurality of base layers by firing the laminate, and eliminating the void layer forming paste pattern to form a void layer.

  According to the said manufacturing method, a big space | gap layer can be formed with few base material layers.

( 7 ) The manufacturing method of the impedance conversion element of the present invention is
What is claimed is: 1. A method of manufacturing an impedance conversion element comprising a first coil element and a second coil element connected in series and transformer coupled to a laminated element formed by laminating a plurality of base material layers,
Forming a conductive paste pattern of the first coil element by coating on the first surface of the first base layer among the plurality of base layers, and applying a paste pattern for forming a void layer on the surface of the conductive paste pattern When,
Applying a conductive paste pattern of a second coil element on the first surface of the second base layer among the plurality of base layers, and applying a paste pattern for forming a void layer on the surface of the conductive pattern; ,
A conductor paste pattern of the first coil element and a third base layer on which the conductor paste pattern of the second coil element is not formed are interposed between the first base layer and the second base layer. And the first base layer, the second base layer, and the third base layer, with the first side of the first base layer facing the first side of the second base layer. Laminating to form a laminate;
Baking the plurality of base layers by firing the laminate, and eliminating the void layer forming paste pattern to form a void layer.

  According to the above manufacturing method, the order of coating formation of the conductor paste pattern and coating formation of the void forming paste can be made constant, so that the pattern forming process can be simplified.

  According to the present invention, the capacitance component can be reduced without changing the conductor pattern of each layer or the interlayer distance (the distance between the conductor patterns in the thickness direction). Along with this, the self resonant frequency can be increased. Further, the insertion loss can be reduced by thickening the line width of the conductor pattern. Furthermore, the coupling distance can be increased by reducing the distance between the conductor patterns.

FIG. 1 is a perspective view of various conductor patterns of the impedance conversion element 21 according to the first embodiment. FIG. 2 is a cross-sectional view of the impedance conversion element 21. As shown in FIG. FIG. 3 is a plan view of each base layer of the impedance conversion element 21. FIG. FIG. 4 is a cross-sectional view of each base material layer before lamination of the impedance conversion element 21. FIG. 5 is a cross-sectional view of the impedance conversion element 22 according to the second embodiment. FIG. 6 is a cross-sectional view of each base material layer before lamination of the impedance conversion element 22. As shown in FIG. FIG. 7 is a view showing the configuration of a wireless communication apparatus such as a mobile phone terminal according to the third embodiment. FIG. 8A is a diagram showing main parasitic capacitances generated in the impedance conversion element according to the present embodiment. FIG. 8B is a diagram showing the main parasitic capacitance C generated in the common mode choke coil which is the comparative example. FIG. 9A and FIG. 9B are diagrams showing parasitic capacitance generated between the first coil element and the second coil element in the impedance conversion element according to the present embodiment. FIGS. 10A and 10B are examples of a circuit diagram of an antenna device disclosed in Patent Document 1. FIG. FIG. 11 is a view showing an example of the conductor pattern of each layer when the impedance conversion circuit 25 shown in FIG. 10 (B) is formed in a multilayer substrate.

First Embodiment
FIG. 1 is a perspective view of various conductor patterns of the impedance conversion element 21 according to the first embodiment. The dielectric base layer on which these conductor patterns are formed is drawn excluding. The circuit diagram of this impedance conversion element 21 is the same as the impedance conversion element 25 shown in FIGS. 10 (A) and 10 (B).

  As shown in FIG. 1, the first loop conductor LP1 by the conductor patterns L1A and L1B, the second loop conductor LP2 by the conductor patterns L1C and L1D, the third loop conductor LP3 by the conductor pattern L2A, and the conductor pattern L2B Fourth loop conductors LP4 are respectively formed. The conductor patterns of each layer are interlayer connected by via conductors.

  On the lower surface of the lowermost base material layer, a terminal corresponding to the first port (feed port) P1, a terminal corresponding to the second port (antenna port) P2, a ground terminal P3 and other mounting terminals (vacant terminals NC ) Is formed. These terminals are formed on the lower surface of the lowermost base layer.

  The first coil element (L1 shown in FIG. 10A) is composed of a first loop conductor LP1 and a second loop conductor LP2. The second coil element (L2 shown in FIG. 10A) is composed of the third loop conductor LP3 and the fourth loop conductor LP4.

  The first loop conductor LP1 and the second loop conductor LP2 are sandwiched in the layer direction between the third loop conductor LP3 and the fourth loop conductor LP4.

  Conductor pattern L1B which is a part of 1st loop-like conductor LP1, and conductor pattern L1C which is a part of 2nd loop-like conductor LP2 are connected in parallel. The conductor pattern L1A which is the remaining portion of the first loop conductor LP1 and the conductor pattern L1D which is the remaining portion of the second loop conductor LP2 are connected in series to the parallel circuit.

  The third loop conductor LP3 according to the conductor pattern L2A and the fourth loop conductor LP4 according to the conductor pattern L2B are connected in series.

  FIG. 2 is a cross-sectional view of the impedance conversion element 21. As shown in FIG. In FIG. 2, the upper part of the figure is represented as a terminal formation surface (mounting surface for mounting on a circuit board).

  As shown in FIG. 2, the impedance conversion element 21 according to the present embodiment is configured in a multilayer body 10 formed by laminating a plurality of base material layers. A plurality of conductor patterns L1A, L1B, L1C, L1D, L2A, L2B and a plurality of void layers AG1, AG2, AG3, AG4 are formed in the multilayer body 10.

  Conductor patterns L1A, L1B, L1C, and L1D constituting the first coil element and conductor patterns L2A and L2B constituting the second coil element have the same general shape in plan view from the stacking direction. Air gap layers AG3 and AG4 are formed between the conductor patterns L1A and L1B of the first coil element and the conductor pattern L2B of the second coil element. Similarly, air gap layers AG1 and AG2 are formed between the conductor patterns L1C and L1D of the first coil element and the conductor pattern L2A of the second coil element.

  The plurality of layers in which the conductor patterns L1A, L1B, L1C, and L1D constituting the first coil element are formed are sandwiched by the layers in which the conductor patterns L2A and L2B constituting the second coil element are formed. The air gap layer AG2 is formed on the surface of the conductor patterns L1C and L1D of the first coil element facing the conductor pattern L2A of the second coil element. The air gap layer AG1 is formed on the surface of the conductor pattern L2A of the second coil element opposite to the conductor patterns L1C and L1D of the first coil element. The air gap layer AG3 is formed on the surface of the conductor patterns L1A and L1B of the first coil element opposite to the conductor pattern L2B of the second coil element. The air gap layer AG4 is formed on the surface of the conductor pattern L2B of the second coil element, which faces the conductor patterns L1A and L1B of the first coil element. In addition, no gap layer is formed between the conductor patterns L1A, L1B and the conductor patterns L1C, L1D that constitute the first coil element.

  FIG. 3 is a plan view of each base layer of the impedance conversion element 21. FIG. In FIG. 3, a round pattern is an interlayer connection conductor (via conductor). FIG. 4 is a cross-sectional view of each base material layer before lamination of the impedance conversion element 21. FIG. 4 is a cross-sectional view at a position indicated by a broken line in FIG.

In this example, a conductor paste pattern and a void pattern for forming a void layer are applied and formed on a predetermined substrate layer of the substrate layers S1 to S6 which are dielectric ceramic green sheets by printing. In FIG. 3, the void layer forming paste pattern and the conductor paste pattern are shown separately in two layers. Each of the base layers S1 to S6 is a sheet before firing of LTCC (Low Temperature Co-fired Ceramics) such as BAS (a mixed ceramic containing BaO, Al ₂ O ₃ and SiO ₂ ). The void layer forming paste is a paste that can disappear when the ceramic body is fired. For example, acrylic resin paste or carbon paste. The conductor paste is, for example, a copper paste.

  A void layer forming paste pattern P (AG1) is formed on the base material layer S3, and a conductor paste pattern P (L2A) is formed on the surface of the void layer forming paste pattern P (AG1).

  A void layer forming paste pattern P (AG3) is formed on the base material layer S5, and conductor paste patterns P (L1A) and P (L1B) are formed on the surface of the void layer forming paste pattern P (AG3). It is done.

  Further, conductor paste patterns P (L1C) and P (L1D) are formed in the base material layer S4, and a paste pattern P for forming an air gap layer is formed on the surface of the conductor paste patterns P (L1C) and P (L1D). AG2) is formed. A conductor paste pattern P (L2B) is formed on the base material layer S6, and a void layer forming paste pattern P (AG4) is formed on the surface of the conductor paste pattern P (L2B).

  Conductor paste patterns P (P1), P (P2), P (P3) and P (NC) for forming terminals are formed in the base material layer S1. Conductor paste pattern P (L2A-1) is formed in base material layer S2.

As described above, a predetermined paste pattern (a void pattern for forming a void pattern and / or a conductor paste pattern) is printed on each base material layer, and the base material layers are laminated and pressed, and then divided into pieces. By pressing the base layer, the conductor paste pattern is spread by the void layer forming paste pattern to have a predetermined line width. The pieces are then fired at a temperature of 800-1000 ° C. in a reducing atmosphere. At the time of this firing, the void layer forming paste mainly disappears by being changed to CO ₂ . That is, the void layer forming paste pattern remains as a void layer pattern.

  In the present embodiment, as shown in FIG. 3 and FIG. 4, the line width of the void layer forming paste is thicker than the line width of the conductor pattern. Therefore, as shown in FIG. 2, the air gap layer forms a space wider than the line width of the conductor pattern. Therefore, the effective dielectric constant between the conductor pattern (L1A, L1B, L1C, L1D) of the first coil element and the conductor pattern (L2A, L2B) of the second coil element is effectively reduced, and the first coil Interlayer capacitance between the element and the second coil element can be further suppressed.

  Here, differences between the impedance conversion element of the transformer structure of this embodiment and the common mode choke coil will be described. FIG. 8A is a diagram showing main parasitic capacitances generated in the impedance conversion element according to the present embodiment. FIG. 8B is a diagram showing the main parasitic capacitance C generated in the common mode choke coil.

  In the common mode choke coil, the normal mode signal is differentially transmitted through the two coils LA and LB. Therefore, the potential difference applied between the two coils LA and LB is doubled (C∝ + V − (− V) = 2 V). Therefore, the capacitive coupling between the coils due to this large potential difference is large.

  On the other hand, since the impedance conversion element of this embodiment has an autotransformer structure, the first coil element L1 (L1A, L1B, L1C, L1D) and the second coil element L2 (L2A, L2B) are connected, And, since the inductance is as small as several nH, the potential difference between the coil elements is small. Therefore, the parasitic capacitance C2 is small (C2∝ + V − (− 0) ≒ V). Further, since the second coil element L2 is divided and has a series structure of the conductor patterns L2A and L2B, the parasitic capacitance C1 generated between the input / output port P2 and the ground is also small (C1∝ + V − (− 0) ≒ V) . Therefore, the parasitic capacitances C1 and C2 generated between the coils are smaller compared to the common mode choke coil.

  FIG. 9A and FIG. 9B are diagrams showing parasitic capacitance generated between the first coil element and the second coil element in the impedance conversion element according to the present embodiment. In FIG. 9A, an air gap layer is added to the circuit diagram of the impedance conversion element according to the present embodiment.

As described above, since the second coil element L2 has a series structure divided into the conductor patterns L2A and L2B, the parasitic capacitance C1 is reduced, but the facing area between the first coil element and the second coil element is increased. The total value of the parasitic capacitances C2a and C2b is large. (Capacitance is proportional to the potential difference, so parasitic capacitances C2a and C2b generated between the first coil element L1 and the second coil element L2 are larger than parasitic capacitances generated between the first coil elements. )
However, as shown in FIG. 9A, since the air gap layer exists between the conductor pattern of the first coil element L1 and the conductor patterns L2A and L2B of the second coil element, the parasitic capacitances C2a and C2b are suppressed. Be done.

  Thus, the self resonance frequency can be increased by reducing the capacitance component.

  In addition, the impedance conversion element of this embodiment is an autotransformer structure, and the connection point of 1st coil element L1 and 2nd coil element L2 exists. Therefore, since there is a via conductor portion structurally, it is impossible to form an air gap layer which covers the entire conductor pattern for forming a coil element. (Since the conductor patterns facing each other are inter-connected at the via conductor portion, the paste for forming the air gap layer can not be applied to the via conductor portion.) That is, the impedance conversion element of this embodiment has a common mode choke coil structure. In comparison, it can be said that areas where parasitic capacitance is large are selectively and intentionally improved.

Second Embodiment
FIG. 5 is a cross-sectional view of the impedance conversion element 22 according to the second embodiment. FIG. 6 is a cross-sectional view of each base material layer before lamination of the impedance conversion element 22. As shown in FIG.

  The impedance conversion element 22 of this embodiment is comprised in the lamination | stacking element | substrate 10 formed by laminating | stacking several base material layers, as it appears in FIG. A plurality of conductor patterns L1A, L1B, L1C, L1D, L2A, L2B and a plurality of void layers AG1, AG2, AG3, AG4 are formed in the multilayer body 10. The planar shape of the conductor pattern of the impedance conversion element 22 of this embodiment is basically the same as that shown in the first embodiment.

  Conductor paste patterns P (L1C) and P (L1D) of the first coil element are formed on the first surface (upper surface in the direction shown in the drawing) of the base material layer S4, which is the first base material layer. The void layer forming paste pattern P (AG2) is formed on the surfaces of the paste patterns P (L1C) and P (L1D). Further, a conductor paste pattern P (L2A) of the second coil element is formed on the first surface (the lower surface in the direction shown in the drawing) of the substrate layer S2 which is the second substrate layer. The void layer forming paste pattern P (AG1) is formed on the surface of (L2A).

  Conductor paste patterns P (L1A) and P (L1B) of the first coil element are formed on the first surface (the lower surface in the direction shown in the drawing) of the substrate layer S5 which is the first substrate layer. The void layer forming paste pattern P (AG3) is formed on the surfaces of the paste patterns P (L1A) and P (L1B). In addition, a conductor paste pattern P (L2B) of the second coil element is formed on the first surface (upper surface in the direction shown in the drawing) of the base material layer S7 which is the second base material layer. A void layer forming paste pattern P (AG4) is formed on the surface of (L2B).

  The base material layer S3, which is a third base material layer, is sandwiched between the base material layer S4 (first base material layer) and the base material layer S2 (second base material layer). The first surface of the base material layer S4 and the first surface of the base material layer S2 face each other via the base material layer S3.

  Similarly, a base material layer S6 which is a third base material layer is sandwiched between the base material layer S5 (first base material layer) and the base material layer S7 (second base material layer). The first surface of the base material layer S5 and the first surface of the base material layer S7 face each other via the base material layer S6.

  The conductor paste pattern of the first coil element and the conductor paste pattern of the second coil element are not formed on the base layers S3 and S6.

As described above, a predetermined paste pattern (a void pattern for forming a void pattern and / or a conductor paste pattern) is printed on each base material layer, and the base material layers are laminated and pressed, and then divided into pieces. The pieces are then fired at a temperature of 800-1000 ° C. in a reducing atmosphere. During the firing, the void layer forming paste disappears as CO ₂ . That is, the void layer forming paste pattern remains as a void layer pattern.

  According to the present embodiment, the pattern formation process can be simplified because the order of the application formation of the conductor paste pattern and the application formation of the void formation paste can be made constant for any base material layer.

  Further, in the present embodiment, as shown in FIGS. 5 and 6, the line width of the void layer forming paste is thinner than the line width of the conductor pattern. Therefore, the conductor paste patterns P (L1A), P (L1B), P (L1C), P (L1D), P (L2A) and P (L2B) are paste patterns for forming a void layer P (AG1), P (AG2) , P (AG3) and P (AG4), and deform as shown in FIG. Therefore, the surface area of the conductor pattern becomes large (the cross-sectional outline becomes long), and the conductor loss is reduced along with the skin effect, and as a result, the insertion loss is suppressed.

Third Embodiment
FIG. 7 is a view showing the configuration of a wireless communication apparatus such as a mobile phone terminal according to the third embodiment. In FIG. 7, only the main parts in the housing of the wireless communication apparatus are shown. The antenna element 11 and the circuit board are provided in the housing, the ground conductor 20 is formed on the circuit board, and the impedance conversion element 21 and the feeding circuit 30 are provided.

  The impedance conversion element 21 is connected between the antenna element 11 and the feeding circuit 30, and matches the impedance of the antenna element 11 with the feeding circuit 30.

  The wireless communication apparatus communicates, for example, cellular band high frequency signals of 900 MHz band or 2 GHz band.

  According to the impedance conversion element 21 of the present embodiment, since the self-resonance frequency can be increased, communication can be performed in a higher frequency band, and the insertion loss can be reduced and the coupling coefficient can be increased.

  Finally, the description of the above embodiments is illustrative in all respects and not restrictive. It will be apparent to those skilled in the art that variations and modifications are possible as appropriate. Needless to say, for example, partial replacement or combination of configurations shown in different embodiments is possible. The scope of the present invention is indicated not by the embodiments described above but by the claims. Further, the scope of the present invention is intended to include all modifications within the scope and meaning equivalent to the claims.

AG1, AG2, AG3, AG4 Air gap layers C, C1, C2, C2 a, C2 b Parasitic capacitance L1 First coil elements L1A, L1 B, L1 C, L1 D, L2 A, L2 B Conductor pattern L2 Second coil element L2 A L2B Conductor pattern LP1 First loop conductor LP2 Second loop conductor LP3 Third loop conductor LP4 Fourth loop conductor P (AG1), P (AG2), P (AG2), P (AG3), P (AG4) ) Paste layer formation paste patterns P (L1A), P (L1B), P (L1C), P (L1D), P (L2A), P (L2B) ... conductor paste patterns P1, P2 ... input / output port P3 ... Ground terminal NC: vacant terminal S1 to S7: base material layer 10: laminated body 11: antenna element 20: ground conductor 21, 22: impedance conversion element 25: impedantan Conversion circuit 30 ... the power supply circuit

Claims (8)

What is claimed is: 1. An impedance conversion element comprising a first coil element and a second coil element that are connected in series and transformer coupled to a laminated element body formed by laminating a plurality of base material layers,
The first coil element is composed of a plurality of conductor patterns provided on different layers of the multilayer body,
The second coil element is composed of a plurality of conductor patterns provided on different layers of the multilayer body,
The conductor pattern constituting the first coil element and the conductor pattern constituting the second coil element have the same general shape in plan view from the stacking direction,
An air gap layer and one or more base layers are disposed between the conductor pattern of the first coil element and the conductor pattern of the second coil element ,
The impedance conversion element characterized in that the air gap layer is not formed between a conductor pattern which constitutes the first coil element and a conductor pattern which constitutes the first coil element.   A first coil element and a second coil element connected in series and transformer coupled to each other, formed in a laminated element having a first main surface and a second main surface in which a plurality of base material layers are laminated; An impedance conversion element comprising a mounting terminal formed on a first main surface of a body,
  The first coil element is composed of a plurality of conductor patterns provided on different layers of the multilayer body,
  The second coil element is composed of a plurality of conductor patterns provided on different layers of the multilayer body,
  The conductor pattern constituting the first coil element and the conductor pattern constituting the second coil element have the same general shape in plan view from the stacking direction,
  The plurality of layers in which the conductor pattern constituting the first coil element is formed is sandwiched between the layers in which the conductor pattern constituting the second coil element is formed,
  An air gap layer and one or more base layers are disposed between the conductor pattern of the first coil element and the conductor pattern of the second coil element,
  Among the plurality of conductor patterns of the first coil element and the plurality of conductor patterns of the second coil element, the conductor pattern closest to the first main surface is the conductor pattern of the second coil element,
  The line width of the conductor pattern of the second coil element is narrower than the line width of the conductor pattern of the first coil element. The air gap layer is a first air gap layer formed on a surface of the conductor pattern of the first coil element, which faces the conductor pattern of the second coil element, and the conductor pattern of the conductor pattern of the second coil element. A second air gap layer formed on the surface facing the conductor pattern of one coil element,
The one or more substrate layers are disposed between the first void layer and the second void layer.
Impedance transformation element according to claim 1 or 2. The plurality of layers in which the conductor pattern constituting the first coil element is formed is sandwiched between the layers in which the conductor pattern constituting the second coil element is formed,
The air gap layer faces the surface of the conductor pattern of the first coil element facing the conductor pattern of the second coil element, or the conductor pattern of the conductor pattern of the second coil element. that is formed on the surface, the impedance conversion device according to any one of claims 1 to 3. The impedance conversion element according to claim 4 , wherein a line width of the air gap layer is thicker than a line width of the conductor pattern. The impedance conversion element according to claim 4 , wherein a line width of the air gap layer is narrower than a line width of the conductor pattern. What is claimed is: 1. A method of manufacturing an impedance conversion element comprising a first coil element and a second coil element connected in series and transformer coupled to a laminated element formed by laminating a plurality of base material layers,
Forming a conductive paste pattern of the first coil element by coating on the first surface of the first base layer among the plurality of base layers, and applying a paste pattern for forming a void layer on the surface of the conductive paste pattern When,
The paste pattern for void layer formation is applied to the first surface of the second base layer among the plurality of base layers, and the conductor paste pattern of the second coil element is applied to the surface of the paste pattern for void layer formation. Process,
The paste pattern for void layer formation is applied on the first surface of the third base layer among the plurality of base layers, and the conductor paste pattern of the first coil element is applied on the surface of the paste pattern for void layer formation. Process,
The first surface of the first base layer is stacked on the second surface of the second base layer, and the second surface of the first base layer is stacked on the first surface of the third base layer. Forming a laminated body;
Baking the plurality of base layers by firing the laminate, and eliminating the void layer forming paste pattern to form a void layer. What is claimed is: 1. A method of manufacturing an impedance conversion element comprising a first coil element and a second coil element connected in series and transformer coupled to a laminated element formed by laminating a plurality of base material layers,
Forming a conductive paste pattern of the first coil element by coating on the first surface of the first base layer among the plurality of base layers, and applying a paste pattern for forming a void layer on the surface of the conductive paste pattern When,
Forming a conductive paste pattern of a second coil element on the first surface of the second base layer among the plurality of base layers, and applying a paste pattern for forming a void layer on the surface of the conductive paste pattern When,
A conductor paste pattern of the first coil element and a third base layer on which the conductor paste pattern of the second coil element is not formed are interposed between the first base layer and the second base layer. And the first base layer, the second base layer, and the third base layer, with the first side of the first base layer facing the first side of the second base layer. Laminating to form a laminate;
Baking the plurality of base layers by firing the laminate, and eliminating the void layer forming paste pattern to form a void layer.

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