JPH11307367A - Thin transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin transformer with high magnetic coupling, good conversion efficiency, and small defective effects from proximity effect between coil patterns in a high-frequency region. SOLUTION: Printed coils 2 and 3 are formed on both faces of an insulating board 1, and a core is assembled in the insulating board 1 with the printed coils 2 and 3. The input coil pattern 2 and the output coil pattern 3 are formed adjacent on the same face of the insulating board 1. At the same time, the input coil pattern 2 and the output coil pattern 3 are formed opposite on the front and rear faces of the insulating board 1. The insulating boards 1 with the input coil pattern 2 and the output coil pattern 3 on the front and rear faces are laminated to form a transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin transformer used for an electronic device or a power supply, and more particularly to a thin transformer used for a DC-DC converter for a switching power supply.

[0002]

2. Description of the Related Art With the recent miniaturization of switching power supplies, power transformers and the like are required to be thinner and have higher frequencies. In order to respond to such demands, various types of thin transformers configured by assembling a magnetic core on a multilayer printed coil board having a coil formed by printed wiring have been used instead of transformers using winding wires. .

[0003] The multilayer printed coil board is laminated with an insulating layer of a required thickness interposed between the coil patterns, and the terminals of each coil pattern are connected to form a coil. It is easier to make thinner than a transformer. Figure 6 shows the appearance of this type of transformer.
FIG. 6A is a cross-sectional view of FIG. 6A, and FIG. The transformers shown in these figures are disclosed in
No. 2,215,962, a coil pattern to be an input coil pattern 2 or an output coil pattern 3 is formed on the front and back surfaces of one insulating base material 1, and these are through holes at the inner ends of the coil patterns 2, 3. 4 and 5 to form coil units 6 and 7, respectively.
These coil units 6 and 7 are laminated and integrated via an insulating material 8, and the outer ends of the coil patterns 2 and 3 are connected via through holes 9 formed after the lamination.

As shown in FIG. 6A, a terminal 11 is inserted into and fixed to the through hole 9 of the laminated body 10 laminated and integrated as described above, and is provided at the center of the laminated body 10. The core 12 made of, for example, an E-shaped core is fitted into a through hole (not shown) by fitting the center foot thereof.

[0005]

In a conventional thin transformer, generally, each of the coil units 6 and 7 includes one of the input coil pattern 2 and the output coil pattern 3 on the insulating base 1. Are formed, and these coil units 6 and 7 are stacked and assembled. Therefore, to increase the transformer coupling,
It was necessary to prepare a plurality of input coil units 6 and output coil units 7 and alternately stack them. For this reason, the number of laminations has increased and the cost has been high.

On the other hand, in a transformer of a type in which a wire is wound, a phenomenon of an increase in wire resistance due to a skin effect at the time of high-frequency driving occurs, and it is necessary to take a countermeasure. It is known that this effect is small and that there is another phenomenon of an increase in high-frequency resistance due to the proximity effect. this is,
This is a phenomenon in which the AC resistance increases due to the influence of the current flowing through a nearby conductor, and this phenomenon occurs remarkably when a current flows in the same direction in an adjacent conductor.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a thin transformer having a small influence of a proximity effect between coil patterns in a high frequency region, a high magnetic coupling, and a good conversion efficiency.

[0008]

In order to achieve this object, a thin transformer according to the first aspect of the present invention has a printed coil formed on both sides of an insulating base material, and a thin transformer formed on the insulating base material on which the printed coil is formed. In a thin transformer having a core assembled, an input coil pattern and an output coil pattern are arranged so as to be adjacent to each other on the same surface of the insulating base, and the input coil pattern and the output coil pattern are connected to the insulating base. And a transformer formed by laminating a plurality of insulating base materials provided with the input coil pattern and the output coil pattern on the front and back surfaces.

As described above, the input coil pattern and the output coil pattern are adjacent to each other in the same layer, and the input coil pattern and the output coil pattern are also arranged on the front and back surfaces of the insulating base material. It is possible to obtain a thin transformer having a small effect of a proximity effect between coil patterns in a high-frequency region, high magnetic coupling, and good conversion efficiency.

According to a second aspect of the present invention, there is provided the thin transformer according to the first aspect, wherein the coil patterns are connected to each other on the opposing surface of the insulating base material adjacent in the laminating direction so that currents flow in opposite directions to each other. It is characterized by.

As described above, by opposing the coil patterns between the insulating base materials, the effect of reducing the proximity effect and increasing the magnetic coupling can be obtained even between the coil patterns on the opposing surfaces of the adjacent insulating base materials. The effect of claim 1 is further promoted.

According to a third aspect of the present invention, there is provided the thin transformer according to the first or second aspect, wherein a space for adjusting the number of turns is provided in an inner peripheral portion of the coil pattern of the insulating base material, and either the input coil pattern or the output coil pattern is provided in the space. It is characterized in that one of them is extended.

Thus, a thin transformer having a high degree of coupling can be provided even in a thin transformer having an input coil pattern and an output coil pattern having different numbers of turns.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an example of the coil unit of the present invention, FIG. 2 is an exploded perspective view thereof, FIG. 3 (A) is a perspective view showing the coil unit cut at the center, and FIG. 3 (B) is this example. FIG. 4 (A) is a sectional view of the coil unit of FIG.
FIG. 2 is a cross-sectional view of a thin transformer configured by the coil unit of the present example.

In the coil unit shown in FIGS. 1 to 3, reference numeral 1 denotes an insulating base made of resin or the like, and reference numerals 2 and 3 denote an input coil pattern and an output coil formed as printed coils on the front and back surfaces of the insulating base 1, respectively. The pattern 21 is a pad formed on the front and back surfaces of the insulating base 1.

The input coil pattern 2 and the output coil pattern 3 are arranged adjacent to each other on the same surface of the insulating substrate 1. Further, the input coil pattern 2 and the output coil pattern 3 are arranged at opposing positions on the front and back surfaces of the insulating base material 1.

The input coil pattern 2 and the output coil pattern 3 of this embodiment each have five turns. The input coil pattern 2 has three turns on the front side and two turns on the back side, and the output coil pattern 3 has two turns on the front side. , 3 on the back
Turns are formed.

Terminals on the inner peripheral side of the input coil patterns 2 on the front and back sides are connected by through holes 4, and terminals on the inner peripheral side of the output coil patterns 3 on the front and back sides are connected by through holes 5. The insulating substrate 1 is provided with an opening 22 for inserting a core.

As shown in the cross-sectional view of FIG. 4A, the coil units 23 are stacked with an insulating material 8 interposed therebetween. The laminated body 24 obtained by laminating is provided with through holes 9 at the portions of the pads 21 so that different coil units 2
The outer peripheral terminals of the input coil pattern 2 and the outer peripheral terminals of the output coil pattern 3 are connected by plating of the through holes 9. In addition, terminal 1
1 is inserted. The E-shaped core 12 is attached to the laminated body 24 by inserting the center foot into the opening 22.

As described above, since the input coil pattern 2 and the output coil pattern 3 are adjacent to each other on the same layer and on the front and back surfaces, such coil units 23 are laminated and the structure shown in FIG.
If a thin transformer as shown in FIG. 1A is formed, a transformer having a small effect of the proximity effect between the coil patterns 2 and 3 in the high-frequency region, high magnetic coupling, and particularly high conversion efficiency in a high-frequency switching power supply can be obtained. Can be

FIGS. 4 (B) and 4 (C) show coil patterns 2 in the laminating direction of a plurality of insulating substrates 1 in the case of carrying out the present invention.
FIG. 3 is a diagram illustrating a preferred example of the arrangement of the output coil patterns 3 and the connection relationship between the respective insulating base materials 1, that is, the direction of current flow. 4 (B) and 4 (C) show the direction of current flow at a certain point in time. The mark indicates the direction of current flow from the back side to the front side of the page, and the cross indicates the front side of the page at that point. 4 shows the direction of current flow from the back to the back side.
As shown in FIG. 4B, the insulating substrate 1 on the adjacent upper layer side
The input coil pattern 2 (output coil pattern 3) on the lower surface of the substrate and the output coil pattern 3 (input coil pattern 2) on the upper surface of the insulating substrate 1 on the lower layer side are vertically aligned (laminated direction).
The input coil patterns 2 of each layer are opposed to each other so that the currents flowing through the input coil pattern 2 and the output coil pattern 3 vertically opposed between the different insulating bases 1 and 1 are opposite to each other. 3 are connected in series or in parallel by the through holes 9 and the terminals 11 in the pads 21, respectively, so that the effect of the proximity effect between the coil patterns 2 and 3 in the high frequency region in the vertical direction is small, and the magnetic coupling is high. Particularly in a high-frequency switching power supply, a transformer with high conversion efficiency can be obtained.

As shown in FIG. 4C, the input coil pattern 2 (output coil pattern 3) on the lower surface of the adjacent upper insulating material 1 is connected to the input coil pattern on the upper surface of the lower insulating material 1. The pattern 2 (output coil pattern 3) is vertically opposed, and each of the insulating base materials 1 is arranged such that a current in the opposite direction flows between the input coil patterns 2 and 2 (output coil patterns 3 and 3) vertically adjacent to each other. FIG. 4 shows that even if the pads 21 of FIG.
The same effect as (B) can be obtained.

FIG. 5 shows another example of the coil unit 23 of the present invention. The transformer of this example has an input coil of eight turns,
The output coil has four turns, and the coil patterns 2 and 3 are provided on the front and back surfaces of the insulating substrate 1 so as to be adjacent to each other by two turns. The input coil pattern 2 having a large number of turns is further provided on the inner peripheral portion of the coil pattern. It is formed by extending two turns each on the front and back surfaces in the winding number adjusting space 25. If a thin transformer is used by laminating such coil units, a thin transformer having a high degree of coupling can be formed as described above even between coil patterns having different numbers of turns.

[0024]

According to the first aspect of the present invention, there is provided a thin transformer in which a printed coil is formed on both surfaces of an insulating base material and a core is attached to the insulating base material on which the printed coil is formed. Pattern
The input coil pattern and the output coil pattern are arranged so as to be adjacent to each other on the same surface of the insulating base material, and the input coil pattern and the output coil pattern are arranged at opposing positions on the front and back surfaces of the insulating base material. Since a plurality of insulating bases provided with the patterns on the front and back surfaces are laminated, at least the input coil pattern and the output coil pattern on the front and back surfaces of the insulating base material are adjacent to each other on the same layer and the front and back surfaces, so that the coil patterns in the high frequency region are formed. Thus, a thin transformer having a small effect of proximity effect, high magnetic coupling, and good conversion efficiency can be obtained.

According to the second aspect, in the first aspect, the coil patterns are connected so that currents flow in opposite directions to the coil patterns facing each other on the opposing surface of the insulating base material adjacent in the laminating direction. Since the effect of reducing the proximity effect and the effect of increasing the magnetic coupling can be obtained even between the coil patterns on the opposing surfaces of the adjacent insulating base materials, the effect of claim 1 is further promoted.

According to a third aspect of the present invention, there is provided the thin transformer according to the first or second aspect, wherein a space for adjusting the number of windings is provided in an inner peripheral portion of the coil pattern of the insulating base material, and either the input coil pattern or the output coil pattern is provided in the space. Since one of them is extended, a thin transformer having a high degree of coupling can be provided even in a thin transformer having an input coil pattern and an output coil pattern having different numbers of turns.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a coil unit of the present invention.

FIG. 2 is an exploded perspective view of the coil unit of FIG.

FIG. 3A is a perspective view showing the coil unit cut at the center, and FIG. 3B is a cross-sectional view of the coil unit of the present example.

FIG. 4A is a cross-sectional view of a thin transformer constituted by the coil unit of the present example, and FIGS. 4B and 4C show the arrangement of coil patterns facing in the laminating direction and the current flowing direction in the present invention. It is a figure explaining a preferable example.

FIG. 5 is an exploded perspective view showing another example of the coil unit of the present invention.

FIG. 6A is a perspective view showing a conventional thin transformer,
(B) is a sectional view thereof.

FIG. 7 is a perspective view showing a layer configuration of a conventional thin transformer.

[Explanation of symbols]

1: insulating base material 2: input coil pattern 3: output coil pattern 4, 5: through hole, 8: insulating material, 9:
Through hole, 11: terminal, 12: core, 21: pad, 22: opening, 23: coil unit, 24: laminate, 25: space for adjusting the number of turns

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI H01F 15/14

Claims (3)

[Claims] 1. A thin transformer in which printed coils are formed on both surfaces of an insulating base material and a core is attached to the insulating base material on which the printed coils are formed. And arranged adjacent to each other on the same surface of the input coil pattern and the output coil pattern,
A thin transformer comprising: a plurality of insulating bases which are arranged at positions facing each other on the front and back surfaces of the insulating base material, and wherein the input coil pattern and the output coil pattern are provided on the front and back surfaces. 2. The thin transformer according to claim 1, wherein the coil patterns are connected to each other on the opposing surface of the insulating base material adjacent in the laminating direction so that currents flow in opposite directions to each other. . 3. The coil according to claim 1, wherein a space for adjusting the number of turns is provided in an inner peripheral portion of the coil pattern of the insulating base material, and either the input coil pattern or the output coil pattern is extended in the space. A thin transformer characterized by being formed.