JPH0787153B2 - Laminated transformer - Google Patents

Description

The present invention relates to a laminated transformer that can be used as various transformers, common mode choke coils, baluns, and the like.

BACKGROUND ART FIG. 10 shows a structure of a conventional laminated transformer.
This figure is a plan view showing the protective substrate and insulating layers in a developed state before lamination, and each insulating layer 52A on which a conductor film is formed,
52B, 53A, 53B are sequentially laminated from the bottom, and protective substrates 54, 51 are further laminated on the upper and lower surfaces of the laminated body. Of these, a second-layer insulating substrate 52B from the bottom has a spiral-shaped wire ring electrode 55B of about 2 turns formed of a conductive film, and one end of the wire ring electrode 55B serves as an external extraction electrode 59, and the other. A through hole terminal 58B having a through hole structure is provided at the end. In addition, the first insulating layer laminated below this
On the surface of 52A, a linear wire ring electrode 55A is formed of a conductive film, one end of this wire ring electrode 55A serves as an external extraction electrode 57, and the other end faces the upper layer through-hole electrode 58b. The flat terminal 58a is formed. Then, by stacking the first insulating layers 52A and 52B, the upper and lower wire ring electrodes 55B and 55A are connected via the through-hole terminal 58b, and one of the outer lead electrodes 57 and 59 is connected. A coil element (primary coil) is formed. The surface of the insulating layer 53A, which is the third layer from the bottom, has a spiral shape formed of a conductor film.
The ring electrode 58A of less than turns is formed, and the ring electrode 5A is formed.
One end of 8A serves as an external extraction electrode 60, and the other end has a flat terminal 61.
a is provided. On the other hand, a linear ring-shaped electrode 56B made of a conductor film is formed on the surface of the fourth insulating layer 53B laminated thereon, and one end of this ring-shaped electrode 56B becomes the external extraction electrode 62. A through hole terminal 61b having a through hole structure is provided at the other end so as to face the lower flat terminal 61a. Thus, the third and fourth insulating layers
By stacking 53A and 53B, the upper and lower coil electrodes 56B and 56A are connected via the through-hole terminal 61b, and the other coil element (secondary coil) is formed between the external extraction electrodes 60 and 62. . Then, the protective substrate 51 and each insulating layer 52A, 52B, 53A,
After sequentially stacking and firing 53B and the protective substrate 54, external electrodes are formed on the outer surface of the stacked body (the external lead-out electrodes 57 and 60 of both coil elements are connected by the external electrodes). A laminated transformer having an equivalent circuit similar to that is constructed.

FIG. 12 shows the structure of another conventional laminated transformer. The surface of each of the insulating layers 72A, 72B, 72C, 72D, 73A, 73B, 73C has a winding wire electrode 75A, 75B of less than one turn (about 3/4 turns) having a substantially equal winding diameter due to the wide conductor film. 75C, 75D, 7
6A, 76B, 76C are provided respectively, and these insulating layers
72A, 72B, 72C, 72D, 73A, 73B and 73C are sequentially laminated from the bottom, and protective substrates 74 and 71 are laminated on the upper and lower sides of the laminated body to form a laminated transformer. Of these, one end of the ring-shaped electrode 75A formed on the surface of the first insulating layer 72A from below is the external extraction electrode 78, and the other end is provided with the flat terminal 79a. A through-hole terminal 79b is provided at one end of a coil electrode 75B formed on the surface of the second insulating layer 72B above it so as to face the lower flat terminal 79a, and a flat terminal 80a is provided at the other end. Has been. 75C of wire ring electrode of the insulating layer 72C of the third layer on it
A through hole terminal 80b is provided at one end of the so as to face the lower flat terminal 80a, and a flat terminal 81a is provided at the other end. Furthermore, the wire ring electrode 75D of the fourth insulating layer 72D on it
A through hole terminal 81b is provided at one end of the so as to face the lower flat terminal 81a, and the other end serves as an external lead electrode 82. Then, when the insulating layers 72A, 72B, 72C, 72D are laminated, the coil electrode 7 is passed through the through-hole terminals 79b, 80b, 81b.
5A, 75B, 75C, 75D are connected, as shown in Fig. 13
One coil element is formed in 77. Similarly, the fifth to seventh insulating layers are laminated from the bottom to form the fifth insulating layer 73A.
The flat terminal 84a at one end of the wire ring electrode 76A formed on the surface of the wire and the through hole terminal 84b provided at one end of the wire ring electrode 76B on the surface of the sixth insulating layer 73B are connected to each other, and The flat terminal 85a provided at the other end and the through-hole terminal 85b provided at one end of the wire ring electrode 76C formed on the surface of the seventh insulating layer 73C are connected to each other by the wire ring electrodes 76A, 76B, 76C. The other coil element is formed between the external extraction electrodes 83 and 86.

[Problems to be Solved by the Invention] In the first conventional example shown in FIG. 10, insulating layers 52B and 53 are provided.
Since the spirally wound coil electrodes 55B and 56A having one or more turns are formed on the surface of A, the coil electrodes 55B and 56A come close to each other on the surface of the insulating layers 52B and 53A. 1
As shown in Fig. 1, a large stray capacitance C ₃ is generated between the adjacent wheel electrodes.

Further, in the second conventional example shown in FIG. 12, each coil is formed by the coil electrodes 75A-75D; 76A-76C on the insulating layers 72A-72D; Since the element is formed, the wire ring electrodes are vertically opposed to each other with the insulating layer (dielectric material) interposed therebetween, and the distance between the conductor films is as small as the thickness of one insulating layer. As shown in the figure, a large stray capacitance C ₄ is generated between the coil electrodes 75A to 75D and 76A to 76C facing each other vertically.

Thus, in any conventional laminated transformer,
A large stray capacitance is generated between the ring electrodes, and the self-resonant frequency in the high-frequency region is lowered due to the capacitive coupling between the ring electrodes that occurs through this stray capacitance, making it difficult to obtain the prescribed inductance and impedance. Was becoming.

Therefore, the present invention has been made in view of the above-mentioned drawbacks of the conventional example, and an object thereof is to prevent the self-resonant frequency from being lowered due to the capacitive coupling between the wire ring electrodes, and to improve the high frequency characteristics of the laminated transformer. To be good.

[Means for Solving the Problems] Therefore, the laminated transformer of the present invention has
The first coil element is formed by stacking a plurality of insulating layers of the first type and the second type having the winding electrodes of less than turns and connecting the winding electrodes of the insulating layers of the first type to each other. In the laminated transformer in which the second coil element is formed by connecting the wire ring electrodes of the second type insulating layers to each other, except for the insulating layer in which the input / output part of the coil element is formed, An insulating layer and an insulating layer of the second type are alternately laminated, and a through-hole connector is provided in the insulating layer of the first type and the second type that is electrically connected between the front and back of each insulating layer,
The first coil element is formed by connecting the ring-shaped electrodes of the first-type insulating layer to each other through the through-hole connector provided in the second-type insulating layer, and the through-hole provided in the first-type insulating layer is formed. While forming the second coil element by connecting the wire ring electrodes of the second type of insulating layer through the hole connector, the wire ring electrode formed in each of the first and second type insulating layers It is characterized in that the winding diameters are substantially equal to each other and that they are substantially parallel in the laminated transformer.

[Operation] In the present invention, an insulating layer having a coil electrode forming the first coil element and an insulating layer having a coil electrode forming the second coil element are formed. Since the layers are alternately laminated, the distance between the wire ring electrodes in the first coil element and the distance between the wire ring electrodes in the second coil element are twice as large as the thickness of the insulating layer. The stray capacitance between the wire ring electrodes (windings) is reduced to half.

For this reason, the capacitive coupling between the coil electrodes of each coil element is reduced, and the self-resonant frequency in the high frequency region is 2
About twice the frequency at which self-resonance occurs moves to the high frequency side, it becomes easy to obtain the desired inductance and impedance, and it is possible to manufacture a laminated transformer having good high frequency characteristics.

Further, since the wire ring electrodes forming the first coil element and the wire ring electrodes forming the second coil element are arranged alternately, the amount of magnetic flux interlinking each other increases. The coupling between both coil elements becomes dense, and the coupling coefficient can be increased.

[Examples] Examples of the present invention will be described below in detail with reference to the accompanying drawings.

1 to 5 show an embodiment of the present invention in which one end of a first coil element L ₅ (primary coil) and one end of a second coil element L ₆ (secondary coil) are connected to each other. It is a two-distribution transformer having an equivalent circuit as shown in FIG. 4 connected in common. This layer transformer 19 ,, the first three layers of ceramic insulating layers 2A constituting the coil element L _5, 2B, 2C and a second coil element L ₆
The three ceramic insulating layers 3A, 3B, 3C constituting the above are alternately laminated, and the protective substrate 4, 1 is further provided on both upper and lower surfaces of the laminated body 15.
Are laminated. On the surface of the first insulating layer 2A from the bottom, a loop electrode 5A that forms a part of the first coil element L ₅ is formed by printing a conductive paste with a constant width. One end of 5A serves as an external extraction electrode 7, and the other end is provided with a flat terminal 8a. On the surface of the second insulating layer 3A, a loop electrode 6A constituting a part of the second coil element L ₆ is wired by printing a conductive paste, and one end of the loop electrode 6A is external. It becomes the extraction electrode 11, and a flat terminal 12a is provided at the other end. Further, the second insulating layer is provided with a through hole connector 8b having a through hole structure corresponding to the lower flat terminal 8a.
Here, the through-hole connector is one in which a conductive paste is printed and baked around the upper surface of the through-hole that penetrates the insulating layer, the inner circumference of the through-hole, and the lower surface of the through-hole. The front and back surfaces of the insulating layer can be electrically connected at the child part. On the surface of the insulating layer 2B of the third layer, the first coil element Senwa electrode 5B constituting part of L ₅ and is wired, the lower through-hole connector 8b to one end of Senwa electrode 5B A through-hole terminal 8c with a through-hole structure is provided facing the
9a is provided. This through-hole terminal also has a structure similar to that of the through-hole connector, and is capable of conducting both the front and back surfaces of the insulating layer. In addition, the insulating layer
2B is provided with a through hole connector 12b facing the flat terminal 12a in the lower layer. On the surface of the fourth insulating layer 3B, a loop electrode 6B forming a part of the second coil element L ₆ is wired by a conductor film, and one end of the loop electrode 6B is provided with a lower layer. A through hole terminal 12c is provided facing the through hole connector 12b, and a flat terminal 13a is provided at the other end. Further, the insulating layer 3B is provided with a through hole connector 9b facing the lower flat terminal 9a. On the surface of the fifth insulating layer 2C, a wire ring electrode forming a part of the first coil element L ₅ is formed.
5C is provided, a through-hole terminal 9c is provided at one end of the ring electrode 5C so as to face the through-hole connector 9b in the lower layer, and the other end is the external lead electrode 10.
Through-hole connector facing flat terminal 1a in the lower layer
13b is provided. The surface of the insulating layer 3C of the sixth layer, and Senwa electrode 6C is provided to constitute a second coil element L _6, to one end of Senwa electrode 6C and the lower through-hole connector 13b Through-hole terminals 13c are provided facing each other, and the other end serves as an external lead electrode 14.

Then, the protective substrate 1 and the insulating layers 2A, 3A, 2B, 3B, 2C, 3
C and the protective substrate 4 are sequentially laminated from the bottom in the state of a green sheet, pressed against each other, and then fired. As a result, the protective substrates 1 and 4 and the insulating layers 2A to 2C and 3A to 3C are sintered and joined to form a laminated body 15. As shown in FIG. 3, a conductor film is formed between the respective layers in the laminated body 15. Embedded. Moreover, as shown in a partially enlarged view in FIG. 5, the through-hole connector 13b
And the ring-shaped electrodes 6B and 6C are connected via the through-hole terminal 13c, the ring-shaped electrodes 6B and 6A are connected via the through-hole connector 12b and the through-hole terminal 12c, and the external lead-out electrodes 11 and 14 are connected to each other. The second coil element L ₆ is constructed, and similarly, the coil electrode is formed through the through-hole connector 9b and the through-hole electrode 9a.
5C and 5B are connected to each other, the ring-shaped electrodes 5B and 5A are connected to each other via the through-hole connector 8b and the through-hole terminal 8a, and the first coil element L ₅ is formed between the external extraction electrodes 7 and 10.
After this, as shown in FIG. 2, the external extraction electrodes 7, 14 and
The external electrodes 16, 17, 18 are formed by printing and baking a conductive paste on the exposed portions of 11, 10. The external extraction electrodes 7 and 14 are connected by the external electrode 16, and both coil elements L ₅ and L ₆ are connected so as to form an equivalent circuit as shown in FIG.

In the above description, one laminated transformer is manufactured as a single unit, but in the actual manufacturing process, a pattern of several tens to several hundreds of wire ring electrodes is formed on the mother sheet of each insulating layer. Then, these mother sheets are laminated to form a mother body of a laminated body, which is then cut into a laminated body of each element unit and fired, and external electrodes are formed on the outer surface of the laminated body.

As a result, as shown in FIG. 3 and FIG. ₅ , the insulating layers 2A, 2B, 2C for the first coil element L ₅ are located between the insulating layers 3A, 3B for the second coil element L ₆ . Since the first coil element L ₅ is sandwiched between the wire ring electrodes 5A, 5B, 5C, the distance between them is twice the thickness of the insulating layer, and similarly the second coil element L ₆ is formed. The distance between the ring electrodes 6A, 6B and 6C is also 2
Times and becomes, Therefore Senwa electrodes 5A, 5B, stray capacitance C ₁ and Senwa electrode 6A generated between 5C, 6B, the stray capacitance C ₁ generated between 6C decreases. That is, even when compared with the conventional example shown in FIGS. 12 and 13, the stray capacitance is halved, and the self-resonant frequency is also twice that of the conventional example. Further, according to such a configuration, the first coil element L ₅ and the second coil element L ₆
However, since they are arranged so as to alternately engage with each other, the mutual induction coefficient between the coil elements L ₅ and L ₆ can be increased. Further, when used in a wide band transformer or a high frequency transformer such as a two-distribution transformer, a uniform distributed capacitance can be obtained by the first coil element and the second coil element.

6 to 9 show another example of the present invention, in which the external extraction electrodes 27, 31, 32, and 35 at both ends of the first and second coil elements L ₂₅ and L ₂₆ are separately provided. It is provided with external electrodes 37, 38, 39, 40 and is used as a pulse transformer or a common mode choke coil. The pattern of the ring electrodes in this embodiment is almost the same as the pattern of the first embodiment, but the positions of the external extraction electrodes are different, so that the wire electrodes 25C, 26B of the fourth to seventh layers are formed. , 25D,
The pattern of 26C is the same as the ring electrodes 5B, 6B, 5C, 6C of the third to sixth layers of the first embodiment, but the ring electrodes 25A, 25B, 26A of the first to third layers are used. Pattern is different from that of the first embodiment. Thus, in this embodiment, the protective substrate 21, the insulating layers 22A, 22B, 23A, 22C, 23B, 22D, 23C and the protective substrate 24 are sequentially laminated from the bottom, and the laminated body 36 is integrated by firing. The laminated transformer 41 is configured by forming both coil elements of the conductive film on the through hole terminal 34c,
Wire ring electrode through through-hole connector 34b and flat terminal 34a
26C and 26B are connected to each other, the coil electrodes 26B and 26A are connected to each other via the through-hole terminal 33c, the through-hole connector 33b and the flat terminal 33a, and the second coil element L ₂₆ is connected between the external extraction electrodes 35 and 32.
Are configured. On the other hand, through the through-hole terminal 30c, the through-hole connector 30b and the flat terminal 30a, the coil electrodes 25D and 2
5C is connected, the loop wheel electrodes 25C and 25B are connected via the through hole terminal 29c, the through hole connector 29b and the flat terminal 29a, and the loop wheel electrodes 25B and 25A are connected via the through hole terminal 28c. First coil element between extraction electrodes 31 and 27
It is composed of L ₂₅ . Then, after stacking the stacked body, external extraction electrodes 37, 38, 39, 40 are provided on the outer surface of the stacked body 36 corresponding to the respective external extraction electrodes 27, 32, 31, 35.

Even in this conventional example, the first coil element L
Insulating layers 22B, 22C, 22D and a second coil element L constituting the first coil element L ₂₅ except for the first insulating layer 22A and the second insulating layer 22B constituting the input / output section of _{25. 26} insulating layers
Since 23A, 23B, and 23C are alternately laminated, as shown in FIG. 8, the coil electrode 25 that constitutes the first coil element L ₂₅ is formed.
The distance between B, 25C and 25D and the distance between the coil electrodes 26A, 26B and 26C forming the second coil element L ₂₆ are twice the thickness of the insulating layer, and the coil is the same as in the first embodiment. The stray capacitance between the electrodes is half that of the conventional one, and the self-resonant frequency is twice the value of the conventional one, and the high frequency characteristics of the laminated transformer can be improved. In addition, since capacitance also occurs between the first coil element and the second coil element, when used in a common mode choke coil whose main purpose is to eliminate common mode, it is possible to eliminate normal mode noise at the same time. Can be done.

In any of the above embodiments, the number of turns of the coil element can be increased by increasing the number of insulating layers stacked.

EFFECTS OF THE INVENTION According to the present invention, an insulating layer provided with a coil electrode forming a first coil element and an insulating layer provided with a coil electrode forming a second coil element are alternately laminated. Since the distance between the wire ring electrodes that configure the same coil element is twice the thickness of the insulating layer and the distance between the wire ring electrodes is large, the stray capacitance generated between the wire ring electrodes is 1 / Reduced to 2. Therefore, the self-resonant frequency in the high frequency range is
The frequency that doubles and causes self-resonance moves to the high frequency side. Therefore, it is possible to prevent the deterioration of the high frequency characteristics due to the decrease of the self-resonant frequency, and it is possible to obtain the laminated transformer having the excellent high frequency characteristics. Further, according to the present invention, the wire ring electrodes forming the first coil element and the wire ring electrodes forming the second coil element are alternately laminated, and both are arranged substantially in parallel, The mutual induction coefficient of the laminated transformer can be increased.

[Brief description of drawings]

FIG. 1 is a plan view showing each insulating layer before stacking according to one embodiment of the present invention, FIG. 2 is a perspective view of a stacked transformer formed by stacking each insulating layer of FIG. 1, and FIG. XX of FIG.
FIG. 4 is an equivalent circuit diagram of the above laminated transformer,
FIG. 5 is an enlarged sectional view showing a part of the above laminated transformer, FIG. 6 is a plan view showing each insulating layer before lamination of another example of the present invention, and FIG. 7 is each insulating shown in FIG. FIG. 8 is a perspective view of a laminated transformer formed by laminating layers, and FIG. 8 is YY of FIG.
A line sectional view, FIG. 9 is an equivalent circuit diagram of the same laminated transformer,
FIG. 10 is a plan view showing each insulating layer before stacking in the first conventional example, FIG. 11 is an explanatory view showing stray capacitance generated in the same stacked transformer, and FIG. 12 is a second conventional example. FIG. 13 is a plan view showing each insulating layer before stacking, and FIG. 13 is a cross-sectional view of a stacked transformer formed by stacking the above insulating layers. 2A to 2C, 3A to 3C ...... Insulating layer 5A to 5C, 6A to 6C ...... Wire ring electrode 8b, 9b, 12b, 13b ...... Through hole connector L ₅ , L ₆ ...... Coil element 22A to 22D, 23A 〜23C …… Insulating layer 25A〜25D, 26A〜26C …… Wheel electrode 29b, 30b, 33b, 34b …… Through hole connector L ₂₅ , L ₂₆ …… Coil element

Claims (1)

[Claims] 1. A plurality of insulating layers of a first type and a second type each having a winding electrode of less than one turn formed of a conductive film are laminated, and the winding electrodes of the insulating layers of the first type are connected to each other. In the laminated transformer in which the first coil element is connected to form the first coil element, and the second type coil element is formed by connecting the wire ring electrodes of the second type insulating layers to each other, the input / output portion of the coil element is formed. Except for the insulating layer, the first type insulating layer and the second type insulating layer are laminated alternately, and the first and second type insulating layers are provided with through-hole connectors electrically connected between the front and back of each insulating layer. , The first coil element is formed by connecting the ring-shaped electrodes of the first type of insulating layer to each other through the through-hole connector provided in the second type of insulating layer, and is provided in the first type of insulating layer. A second coil element is formed by connecting the ring-shaped electrodes of the second type of insulating layer to each other through the through-hole connector, A laminated transformer, wherein the winding electrodes formed on each of the first and second types of insulating layers have substantially equal winding diameters so that they are substantially parallel in the laminated transformer.