JPH04151810A - Planar transformer - Google Patents

Abstract

PURPOSE:To miniaturize the title planar transformer to obtain the stable characteristics by a method wherein respective coil patterns are formed in the conductive layers formed on both surfaces of the thin plate type substrate. CONSTITUTION:The title planar transformer is composed of the first coil patterns 2 formed in one of the conductor layers laminated on the surface face and the rear surface of the thin plate type substrate 1 consisting of an insulating material and the second coil patterns 3 on the other conductive layer. The first and second patterns 2 and 3 are respectively formed zigzag in a meandering crank shape while the whole body is overlapped through the substrate 1 so as to be electromagnetically coupled. Through these procedures, the title planar transformer can be formed in almost flat plate type to be miniaturized, furthermore the positions of respective coil patterns 2, 3 can be fixed to the substrate 1 thereby obtaining the stable characteristics.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a planar transformer used for baluns, distribution circuits, branch circuits, etc., mainly in high frequency regions such as TV broadcast frequencies.

[Conventional technology]

Conventionally, in high frequency areas such as TV broadcasting frequencies,
Various types of transmission line transformers are used, including transmission line transformers, baluns, distribution transformers, and branch transformers. As shown in Fig. 11, the transmission line transformer T1 inverts the signal input from the input terminal K and outputs it to the output terminal OUT.
As shown in FIG. 12(a) (+1), a winding wire]6 is inserted into a cylindrical shape called a bead type or a loidal type. It is constructed by wrapping it in a shape. A balun is a device that connects an unbalanced line and a balanced line. For example, a balun that connects a 75Ω coaxial cable and a 300Ω balanced cable has one winding as shown in FIG. 1 transformer T21. It is constructed using two T22s so that the impedance ratio between input and output is 1:4. Such a transformer T21. As shown in FIG. 14, the T22 is constructed by winding a winding 16 around a core 15 called a spectacles-shaped core 15 having a pair of through holes 17. As shown in FIG. 15, the distribution circuit divides the signal input from the input terminal IN into equal parts using the branch transformer T3, and outputs the output equally from the two output terminals OUT], , 0 and IT2. It is something. Distribution transformer T3
As shown in FIG. 16, it is constructed by winding a wire [6] around a core 15, which is called a bead type similar to a transmission line transformer. For example, as shown in FIG.
1. , rr 2 and winding n3. Branch transformer T4 configured such that the winding ratio of n4 is 1:3.
is configured to send out the signal input from the input terminal IN from the output terminal OUT and the branch output terminal BOUT. As shown in FIG. 18, the branch transformer T7I is wound around a core 15 called a spectacle-shaped core similar to a balun]
It is constructed by winding 6.

[Problem to be solved by the invention]

Each of the above-mentioned transformers is constructed by winding the winding 16 through a core 15 having a through hole, and the core 15 is cylindrical and bulky. A problem arises in that the overall shape becomes relatively large. In addition, since the winding 16 is inserted through the core 5, it is difficult to mechanize the work of winding the winding 16, and furthermore, the winding 16 may be misaligned with respect to the core 15, resulting in variations in characteristics. The problem is that there are many. The present invention aims to solve the above-mentioned problems, and provides a planar transformer that can be made small, can be manufactured automatically, and has stable characteristics.

[Means to solve the problem]

In the structure of claim 1, in order to achieve the above object, the first coil pattern is formed on one side of the conductive layer laminated on both sides of the thin plate-like base material made of an insulating material, and the first coil pattern is formed on the other side. A second coil pattern is formed which is electromagnetically coupled to the second coil pattern. In the structure of claim 2, the first coil pattern and the second coil pattern are formed so that at least a portion thereof overlaps with the base material in between. In the structure of claim 3, the one having a larger number of turns of the first coil pattern and the second coil pattern is formed wider than the one having a smaller number of turns. In the configuration of the fourth aspect, the one having a larger number of turns of the first coil pattern and the second coil pattern is formed within the range occupied by the one having a smaller number of turns. In the structure of claim 5, cores made of magnetic material are disposed on both sides of the planar transformer according to claim 1. In the structure of claim 6, a first coil pattern is formed on one side of the conductive layer laminated on both sides of a thin plate-like base material made of an insulating material, and a second coil electromagnetically coupled with the first coil pattern is formed on the other side. A pattern is formed, and a terminal pattern is formed on one side of the base material to connect each coil pattern to an external line.The base material is mounted on a board having a ground pattern and a conductive pattern, and the terminal pattern is connected to a ground pattern and a conductive pattern. An opening is connected to the conductive pattern and has a periphery that is approximately the same shape as the periphery of the base material at a portion of the substrate corresponding to the base material.

[Effect]

According to the structure of claim 1, coil patterns are formed on each of the conductive layers formed on both sides of the thin plate-like base material, and one side is used as a primary coil and the other as a secondary coil, so that Since the coil pattern can be formed into a flat plate, it can be made smaller than before, and the coil pattern can be formed by etching the conductive layer, printing the conductive layer, etc., making manufacturing automated. On the other hand, since each coil pattern has a fixed position, stable characteristics can be obtained. The configurations of claims 2 to 4 are preferred embodiments for obtaining desired characteristics as a transformer. In the structure of claim 5, by adding a core made of a magnetic material, the characteristic impedance between each coil pattern and the ground can be increased, and desirable performance as a transformer can be obtained. In the structure of claim 6, a terminal pattern for connecting each coil pattern to an external line is formed on one side of the base material, and the base material is mounted on a board having a grounding pattern and a conductive pattern to ground the terminal pattern. Since an opening is connected to the pattern and the conductive pattern and has a periphery that is approximately the same as the periphery of the base material at a portion of the substrate corresponding to the base material, the presence of the opening makes it possible to connect to the ground pattern on the substrate. The coupling between the transformer and the coil pattern on the base material is reduced, the characteristic impedance of the coil pattern to the ground can be increased, and desirable performance as a transformer can be obtained.

【Example】

(Example 1) In this example, a transmission line transformer T1 is shown. The transmission line transformer T] has the configuration shown in FIG. 11 as a circuit, and in the present invention, instead of winding the core with a winding, as shown in FIG. The first coil pattern 2 is formed on one side of conductive layers laminated on both the front and back surfaces of a thin plate-like base material 1, and the second coil pattern 3 is formed on the other side. The base material 1 is made of an insulating film having a thickness of several tens of microns. The first coil pattern 2 and the second coil pattern 3 are each formed in a crank-like meandering shape, and are arranged so as to overlap with each other through the base material 1 so as to be electromagnetically coupled to each other. It has become. That is, both coil patterns 2.3
It is possible to use one of them as a primary coil and the other as a secondary coil. Here, each coil pattern 2.3 is formed by etching the copper film laminated substrate, printing a conductive layer on the surface of the base material, or vapor-phase plating of a conductive material on the surface of the base material. It is formed by By the way, in the transmission line 1 Herance T1, the characteristic impedance between the primary coil and the secondary coil is set to several ohms to several tens of ohms so that the power transmission efficiency can be high. The characteristic impedance between the coil and the ground is set to be as large as possible. In the configuration of this embodiment, the characteristic impedance between the primary coil and the secondary coil is the same as that between the first coil pattern 2 and the second coil pattern.
By adjusting the width of the coil pattern 3, the line capacitance per unit length can be set to a desired value. Further, as described above, the characteristic impedance between the primary coil and the secondary coil and the ground can be increased by bending the first coil pattern 2 and the second coil pattern 3 in a crank shape. It can be done. FIG. 2 shows the frequency-transfer characteristics when the base material 1 is 25 px and the line lengths of the first coil pattern and the second coil pattern 3 are each 80 a+. As is clear from this figure, the transmission loss is relatively small in the frequency range of about the TV broadcast frequency, and practical characteristics can be obtained. <Example 2> In this example, the h-lance lower 21. used in the balun shown in FIG. Indicates T22. The balun uses two transformers T21. with 1.1 winding. As shown in FIG. 3, both transformers T21 and T22 are formed on one substrate 1. 2 coil patterns 3132 are formed on the front and back sides of the base material 1 in such a manner that they overlap each other in their entirety.Furthermore, each of the fill patterns 21, 22, 31, and 32 is formed in a bent shape in a crank shape. The first coil patterns 2], 22 in the transformers T21 and T22 are formed separated from each other, as shown in FIG. A through hole 51.52 is formed at the tip of the transformer T21..T22.The second coil pattern 31.32 in each transformer T21..T22 has one end connected to each other and the other end are extended to positions corresponding to the through holes 51 and 52. The first coil pattern 21 of the transformer T21 and the second coil pattern 32 of the transformer T22 are electrically connected via the through hole 51, and , the first coil pattern 22 of the transformer T22
and the second coil pattern 3] of the transformer T2] are electrically connected via a through hole 52. Other configurations and effects are the same as in the first embodiment. The thickness of the base material 1 is 25 μm, each coil pattern 2] 223
1. FIG. 4 shows the transmission characteristics when each of the lengths of 32 and 40 is equal to 40. As is clear from this figure, TV
Good transfer characteristics can be obtained in the broadcast frequency range. (Example 3) This example corresponds to the distribution transformer T3 shown in FIG. 15, and as shown in FIG. A coil pattern 2.3 is formed. As shown in FIG. 5(a), a connection pattern 6 is extended from one end of the first coil pattern 2 formed on one surface of the base material 1, and a through hole 53 is formed at the tip of the connection pattern 6. It is formed. Also, the fifth
As shown in Figure (b), one end of the second coil pattern 3 formed on the other surface of the base material 1 is extended to a position corresponding to the through hole 53. First coil pattern 2 and second coil pattern
It is electrically connected to the coil pattern 3 through the through hole 53. The other configurations and operations are the same as those in the first embodiment, so their explanations will be omitted. (Example 4) This example corresponds to the branch transformer T4 shown in FIG. 17, and as shown in FIG. 6, two sets of windings are formed on one base material 1. has been done. Two crank-shaped first coil patterns 21 and 22 are formed on one side of the base material 1, and a spiral second coil is formed on the other side at a position overlapping the first coil pattern 2. Two patterns 31 and 32 are formed. The second coil pattern 3 has a triple spiral shape and has a narrower line width than the first coil pattern 2. As a result, two sets of windings with windings of ]:3 are formed. Through holes 54 to 57 are formed at both ends of both second coil patterns 31 and 32, respectively. Also,
Both first coil patterns 21. ．． A connection pattern 7 is extended to one end of 22, and the tip of the connection pattern 7 is connected to a second coil pattern 31. ．． 32 to a position corresponding to a through hole 54,55 formed at one end. A terminal pattern 8 is formed on the same surface as the first coil pattern 21.22 at a position corresponding to the through hole 56° 57 formed at the other end of the second coil pattern 31.32,
Both second coil patterns 31, 32 are electrically connected to the terminal pattern 8 via through holes 56, 57. Therefore, the first coil pattern 2] and the second coil pattern 32 are electrically connected via the through hole 55, and the first coil pattern 22 and the second coil pattern 31 are connected to each other via the through hole 55. electrically connected via. Furthermore, the second coil pattern 31.32
One end is connected to the terminal pattern 8 through through holes 56 and 57. The other configurations and operations are the same as those in the embodiment, so their explanations will be omitted. (Example 5) In this example, as shown in FIG. 9). With this configuration, it is possible to increase the characteristic impedance between the first coil pattern 2 and the second coil pattern 3 and the ground. Since the core 9 has a flat plate shape, it is not bulky like a conventional cylindrical core, and the overall shape can be made relatively small. It goes without saying that the planar transformer A disposed between the pair of cores 9 may have the same configuration as in the first to fourth embodiments. (Example 6) This example shows the other side of the transmission line transformer T1, and as shown in FIG. 8(b), through holes 58 and 59 are formed at both ends of the second coil pattern 3. Terminal patterns 8 are formed on the surface of the base material 1 on which the first coil pattern 2 is formed at positions corresponding to the 585 through holes. Further, both ends of the second coil pattern 3 are connected to the terminal pattern 8 via through holes 58 and 59. That is, the connection portions of the first coil pattern 2 and the second coil pattern 3 to the external line are formed on the same surface of the base material 1. Further, both ends of the first coil pattern 2 and one end of each terminal pattern 8 are extended to the edge of the base material 1. Therefore, both ends of the first coil pattern 2 each function as a terminal pattern. When mounting the transmission line transformer T1 formed in this way on the substrate 1o together with other circuit components, etc., as shown in FIG. 11 is formed, and a conductive pattern 12 connectable to the first coil pattern 2 and the terminal pattern 8 is formed around the opening 11. A base material 1 is placed on such a substrate 1o.
Both coil patterns 2.3 are electrically connected to the conductive pattern 12 using solder or the like. Here, the substrate 10 is a double-sided substrate, and the opposite side of the conductive pattern 2 has a ground pattern 13 over the entire surface.
is formed. Further, the ground pattern 13 is connected to the conductive pattern 12 via a through pole 14. A single-sided substrate may be used as the substrate 10, and in that case, as shown in FIG. 10, the entire surface except for the conductive pattern 12 may be made into a ground pattern 13. According to the above-described configuration, since the opening 11 is formed in the substrate 10, the coupling capacitance between the coil pattern 2.3 on the substrate 1 and the ground pattern 13 on the substrate 10 can be reduced. This makes it possible to increase the characteristic impedance between each coil pattern 2, 3 and the ground. Although this embodiment exemplifies a transmission line transformer, it goes without saying that the same technical concept can be applied to other transformers.

【Effect of the invention】

As described above, according to the structure of claim 1, the present invention forms coil patterns on each of the conductive layers formed on both sides of a thin plate-like base material, and one side is a primary coil and the other side is a secondary coil. Because the coil pattern is used as a flat plate, it can be made smaller than before, and the coil pattern can be formed by etching the conductive layer, printing the conductive layer, etc., making it easier to manufacture. It can be automated, and since each coil pattern is fixed in position with respect to the base material, stable characteristics can be obtained. In the structure of claim 5, by adding the core made of a magnetic material, the characteristic impedance between each coil pattern and the ground can be increased, and desirable performance as a transformer can be obtained. In the structure of claim 6, a terminal pattern for connecting each coil pattern to an external line is formed on one surface of the base material, and the terminal pattern is grounded by mounting the base material on a board having a grounding pattern and a conductive pattern. Since the opening is connected to the pattern and the conductive pattern and has a periphery that is approximately the same as the periphery of the base material at a portion of the substrate corresponding to the base material, the presence of the opening allows the connection between the grounding pattern on the substrate and the base material. The capacitive coupling between the material and the second coil pattern is reduced, the characteristic impedance of the coil pattern to the ground can be increased, and desirable performance as a transformer can be obtained.

[Brief explanation of the drawing]

1(a) and (b) are respectively a perspective view and a sectional view showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of the same operation, and FIG.
a) and (b) are a top perspective view and a bottom perspective view showing Embodiment 2 of the present invention, respectively; FIG. 4 is an explanatory view of the same operation;
5(a) (+)) are a top perspective view and a bottom perspective view showing Embodiment 3 of the present invention, respectively, and FIGS. 6(a)(b)
) are respectively a top perspective view and a bottom perspective view showing Embodiment 4 of the present invention, FIG. 7 is a sectional view showing Embodiment 5 of the present invention, and FIG. Example 6 of the present invention
A perspective view of the top side and a perspective view of the bottom side without showing the base material used for the
Fig. 9 is an exploded perspective view showing the same configuration, Fig. 10 is an exploded perspective view showing another example of the same configuration, Fig. 11 is a circuit diagram showing the transmission line transformer, and Fig. 12 (a) (b). 13 is a perspective view showing a conventional transmission line transformer, 13th (Z is a circuit diagram without a balun), 174 is a perspective view showing a conventional balun, 15 is a circuit diagram showing a distribution circuit, and 16 is a perspective view showing a conventional distribution transformer, FIG. 17 is a circuit diagram showing a branch circuit, and FIG. 18 is a perspective view showing a conventional branch transformer. 1... Base material, 2... First material. Coil pattern, 3rd and 2nd coil pattern. Agent Patent attorney Ishi 1) Chief 7 Figure 13 Figure 15 Figure 16

Claims (1)

[Scope of Claims] (1) A first coil pattern is formed on one side of a conductive layer laminated on both sides of a thin plate-like base material made of an insulating material, and a second coil pattern is electromagnetically coupled to the first coil pattern on the other side. A planar transformer characterized by forming a coil pattern. (2) The planar transformer according to claim 1, wherein the first coil pattern and the second coil pattern are formed so that at least a portion thereof overlaps with the base material in between. (3) The planar transformer according to claim 1, wherein the one having a larger number of turns of the first coil pattern and the second coil pattern is formed wider than the one having a smaller number of turns. (4) The planar transformer according to claim 1, wherein the one having a larger number of turns of the first coil pattern and the second coil pattern is formed within a range occupied by the one having a smaller number of turns. (5) A planar transformer, characterized in that a core made of a magnetic material is disposed on both sides of the planar transformer according to claim 1. (6) A first coil pattern is formed on one side of a conductive layer laminated on both sides of a thin plate-like base material made of an insulating material, and a second coil pattern that is electromagnetically coupled to the first coil pattern is formed on the other side. , a terminal pattern is formed on one side of the base material to connect each coil pattern to an external line, and the base material is mounted on a board having a grounding pattern and a conductive pattern, and the terminal pattern is connected to the grounding pattern and the conductive pattern. A planar transformer in which an opening having a circumferential edge approximately equal to the circumferential edge of the base material is formed in a portion of the substrate corresponding to the base material.