JP2013171933A - Thin transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin transformer capable of finely adjusting an inductance value with a simple constitution.SOLUTION: A thin transformer according to one embodiment comprises: a bobbin 10 having a cylinder part 11 around which a primary side coil is wound; a multilayer substrate 20 formed by laminating plural substrates 21 on a main face of which a spiral conductor pattern 22 constituting a secondary side coil is formed upward and downward; and a core 70 having core body parts 71, 72a forming a magnetic path between the primary side coil and the secondary side coil, and an extension core part 72b extending along the main face of the multilayer substrate 20 from the core body part and arranged above a coil formation region C in which the secondary side coil is formed.

Description

  The present invention relates to a thin transformer used for a power supply module incorporating a power conversion circuit such as an AC-DC converter.

  Conventionally, a thin transformer composed of a sheet coil built in a multilayer substrate is known for both the primary winding and the secondary winding. In some cases, the inductance value of the thin transformer is finely adjusted for the purpose of outputting a highly accurate secondary voltage. In such a case, the inductance value is adjusted by adding an external circuit including a capacitor or the like to the thin transformer.

  In addition, as shown in FIG. 1, Patent Document 1 has a secondary winding of a flat cable band in which coated conductors corresponding to the number of output channels are arranged in parallel, and a multi-channel output in which the output balance of each channel is uniform. A type transformer is disclosed.

JP 2001-135532 A

  When adjusting the inductance value of a thin transformer by increasing / decreasing the number of turns of the secondary winding, there is a problem that the inductance value changes greatly only by increasing / decreasing one turn and cannot be adjusted to a desired inductance value. is there.

  Further, the method of adding an external circuit for adjusting inductance to the thin transformer has a problem that the configuration of the thin transformer becomes complicated and the cost increases. Furthermore, in the case of a multi-output type transformer that outputs a plurality of secondary voltages, adjusting a certain secondary voltage causes other secondary voltages to change at the same rate, so that all secondary voltages can be changed to each desired voltage. There is also a problem that the value cannot be adjusted.

  Therefore, an object of the present invention is to provide a thin transformer capable of finely adjusting an inductance value with a simple configuration.

A thin transformer according to one embodiment of the present invention is provided.
A primary winding;
A multilayer board formed by laminating a plurality of boards each having a spiral conductive pattern constituting the secondary winding formed on the main surface; and
A core body that forms a magnetic path between the primary winding and the secondary winding; and the secondary winding that extends from the core body along the main surface of the multilayer substrate. A core having an extended core portion covering at least a part of the winding forming region formed with
It is characterized by providing.

In the thin transformer,
The extended core portion of the core may cover the entire winding formation region.

In the thin transformer,
The secondary winding is composed of one or a plurality of electrically connected conductor patterns, and generates a first secondary voltage, and the first secondary winding. A second secondary winding that is configured from one or a plurality of the electrically connected conductor patterns that do not constitute a secondary winding and generates a second secondary voltage. .

In the thin transformer,
Of the conductor pattern constituting the first secondary winding and the conductor pattern constituting the second secondary winding, the lengths of the portions covered by the extension core portion may be different from each other. Good.

In the thin transformer,
The primary winding is composed of a conductive wire wound around a cylindrical portion of a bobbin,
The core includes a first base portion disposed on a lower surface side of the multilayer substrate, a first pillar portion standing from the first base portion and inserted into the cylindrical portion of the bobbin, and the first pillar portion. A first core including a second pillar portion inserted through a through-hole penetrating the multilayer substrate in a region standing from a base and surrounded by the conductor pattern; and disposed on an upper surface side of the multilayer substrate You may have a 2nd core including the said 2nd base and the said 2nd base, and the 2nd core containing the said extended core part provided integrally.

In the thin transformer,
One end of the multilayer substrate is provided with a cutout portion larger than the planar shape of the bobbin,
The bobbin may be accommodated in the notch so as not to contact the multilayer substrate and to be disposed in the same plane as the multilayer substrate.

In the thin transformer,
The core may be made of ferrite.

  In the thin transformer according to the present invention, a secondary winding is formed extending from the core body forming the magnetic path between the primary winding and the secondary winding along the main surface of the multilayer substrate. By providing the extended core portion that covers at least a part of the formed winding formation region, it is possible to finely adjust the number of magnetic fluxes linked to the secondary winding.

  As a result, according to the present invention, the inductance value of the thin transformer can be adjusted more finely than a case where the number of turns of the secondary winding is increased or decreased with a simple configuration without adding an inductance adjustment circuit or the like. it can.

It is a top view of the module which has a thin transformer by one Embodiment of this invention. It is a top view of the multilayer substrate of the module shown in FIG. It is sectional drawing of the thin transformer by one Embodiment of this invention. (A) And (b) is a top view which shows an example of a conductor pattern.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each figure, the component which has an equivalent function is attached | subjected the same code | symbol, and detailed description of the component of the same code | symbol is not repeated.

  First, the thin transformer according to the present embodiment will be described with reference to FIGS.

  FIG. 1 shows a plan view of a module having a thin transformer 1 according to an embodiment of the present invention. FIG. 2 is a plan view of the multilayer substrate 20 of the module. FIG. 3 is a cross-sectional view of a thin transformer 1 according to an embodiment of the present invention.

  The module shown in FIG. 1 includes a thin transformer 1 and a thin core coil (choke coil) 2 that constitute a power conversion circuit such as an AC / DC converter circuit.

  As shown in FIG. 3, the thin transformer 1 has a bobbin 10 having a cylindrical portion 11 around which a primary side winding is wound, and a spiral conductor pattern constituting the secondary side winding formed on the main surface. A multilayer substrate 20 formed by laminating a plurality of substrates vertically and a core 70 are provided.

  As shown in FIG. 3, the bobbin 10 includes a cylindrical portion 11 around which the primary winding of the thin transformer 1 is wound, and flange portions 12 provided at both ends of the cylindrical portion 11. The bobbin 10 is preferably made of resin.

  The primary winding is composed of a conducting wire 13 wound around the cylindrical portion 11 of the bobbin 10. As shown in FIG. 1, one end of the conducting wire 13 is pulled out from the bobbin 10 and soldered to a land provided on the surface of the multilayer substrate 20. In addition, in order to suppress the eddy current in a primary side winding as much as possible as the conducting wire 13, it is to use a litz wire in which a thin copper wire (for example, 0.08 mm diameter) subjected to insulation treatment is twisted. preferable.

  As shown in FIG. 2, a cutout portion 26 larger than the planar shape of the bobbin 10 is provided at one end of the multilayer substrate 20. As shown in FIG. 1, the bobbin 10 is accommodated in the cutout portion 26 so as not to contact the multilayer substrate 20 and to be disposed in the same plane as the multilayer substrate 20.

  As shown in FIG. 3, the multilayer substrate 20 is configured by laminating a plurality of substrates 21 each having a spiral conductor pattern 22 formed on the main surface. The conductor pattern 22 is formed on both surfaces of the substrate 21, and a prepreg 24 is interposed between the substrates 21. The conductor pattern 22 may be formed only on one side of the substrate 21. The conductor patterns 22 are electrically connected by a via 23 or a through hole (not shown) provided on the substrate 21 to constitute a secondary winding. Note that the secondary winding may be constituted by one conductor pattern 22.

  As shown in FIG. 1, various electronic components 27 such as chip components and ICs are soldered to the surface of the multilayer substrate 20.

  As described above, the primary side winding of the thin transformer 1 is composed of the conductive wire 13 wound around the bobbin 10, while the secondary side winding is composed of one conductor pattern 22 or a plurality of electrically connected wires. The conductor pattern 22 is used. That is, the secondary winding is composed of a sheet coil built in the multilayer substrate 20. Note that the primary winding is not limited to the case of the conductive wire 13 wound around the cylindrical portion 11 of the bobbin 10 and is configured of a sheet coil built in the multilayer substrate 20 as with the secondary winding. May be.

  As shown in FIG. 2, the multilayer substrate 20 is provided with through holes 25 and 30 to 32. The through hole 25 is formed so as to penetrate the multilayer substrate 20 in the region surrounded by the conductor pattern 22 as shown in FIG. 2, and allows the column portion 71c of the core 70 of the thin transformer 1 to be inserted as shown in FIG. . The through holes 30 to 32 are provided in order to insert the column part of the core 50 of the thin core coil 2.

  Next, the configuration of the core 70 will be described in detail.

  As shown in FIG. 3, the core 70 includes a first core 71 and a second core 72. The core 70 is made of ferrite, for example. As shown in FIG. 3, the core 70 gap may be filled with an insulating material 73.

  The first core 71 includes a base portion 71 a disposed on the lower surface side of the multilayer substrate 20 and column portions 71 b and 71 c erected from the base portion 71 a. The planar shape of the base 71a is substantially rectangular. As shown in FIG. 3, the column portion 71 b is inserted into the cylindrical portion 11 of the bobbin 10, and the column portion 71 c is inserted into the through hole 25 of the multilayer substrate 20.

  The second core 72 includes a base portion 72a disposed on the upper surface side of the multilayer substrate 20 and an extended core portion 72b provided integrally with the base portion 72a. As shown in FIG. 1, the planar shape of the base 72 is substantially a home base shape. The planar shape of the base 72 a is substantially the same rectangular shape as the base 71 a of the first core 71.

  As can be seen from FIGS. 1 to 3, the extended core portion 72 b is disposed above the winding formation region C so as to cover the entire winding formation region C. Here, the winding formation region C is a region where the secondary winding of the multilayer substrate 20 is formed as shown in FIG.

  From a functional point of view, the core 70 can be understood as having a core main body portion that forms a magnetic path between the primary side winding and the secondary side winding, and an extended core portion 72b. The core main body is composed of a first core 71 and a base 72 a of the second core 72. As shown in FIG. 3, the extended core portion 72 b extends from the core main body portion along the main surface of the multilayer substrate 20.

  In addition, the extended core part 72b does not necessarily need to cover the whole winding formation area C. The area and area to be covered may be determined according to a desired inductance value. That is, the extended core portion 72b covers at least a part of the winding formation region C according to a desired inductance value.

  As described above, in the thin transformer 1 according to the present embodiment, the extended core portion 72b is provided so that the second core 72 has a substantially home base shape, thereby reducing the number of magnetic fluxes linked to the secondary winding. adjust. As a result, the inductance value of the thin transformer 1 is made finer than when the number of turns of the secondary winding (that is, the number of conductor patterns 22) is increased or decreased with a simple configuration without adding an inductance adjustment circuit or the like. Can be adjusted.

  The planar shape of the second core 72 is not limited to a substantially home base shape, and may be any shape as long as it is formed so as to cover the winding formation region C, such as a T-shape.

  Further, the extended core portion is not limited to being provided in the second core 72, but may be provided in the first core 71, or may be provided in both the first core 71 and the second core 72. Good.

  Further, in the present embodiment, the core 70 is configured by combining the U-shaped first core 71 and the flat second core 72, but the present invention is not limited to this. You may comprise the core which has a core main-body part and an expansion core part by combining a member.

  Next, a modification of the thin transformer according to the present embodiment will be described. The thin transformer according to the modification is a multi-output transformer capable of outputting a plurality of secondary voltages.

  The secondary winding of the thin transformer according to this modification is composed of a plurality of groups. That is, the secondary side winding includes a first secondary side winding that generates the first secondary voltage (V1) and a second secondary side winding that generates the second secondary voltage (V2). With lines. The first secondary winding is composed of one or a plurality of electrically connected conductor patterns. The second secondary winding is composed of one or a plurality of electrically connected conductor patterns that do not constitute the first secondary winding.

  FIG. 4A is a plan view showing an example of a conductor pattern 22A constituting the first secondary winding, and FIG. 4B is a conductor pattern constituting the second secondary winding. It is a top view which shows an example of 22B.

  As shown in FIGS. 4A and 4B, the lengths of the portions of the conductor pattern 22A and the conductor pattern 22B that are covered by the extended core portion 72b are different from each other. Thereby, the number of magnetic fluxes linked to the conductor pattern can be individually changed between the first secondary winding and the second secondary winding. Therefore, according to this modification, the secondary voltages V1 and V2 can be individually adjusted. In addition to the length of the portion covered by the extended core portion 72b, the thickness and shape of the conductor pattern may be changed.

  Based on the above description, those skilled in the art may be able to conceive additional effects and various modifications of the present invention, but the aspects of the present invention are not limited to the individual embodiments described above. . You may combine suitably the component covering different embodiment. Various additions, modifications, and partial deletions can be made without departing from the concept and spirit of the present invention derived from the contents defined in the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Thin transformer 2 Thin core coil 10 Bobbin 11 Tube part 12 Flange part 13 Conductor 20 Multilayer substrate 21 Board | substrate 22,22A, 22B Conductor pattern 23 Via 24 Prepreg 25 Through-hole 26 Notch 27 Electronic component 30, 31, 32 Through-hole 70 (Transformer) core 71 first core (U-shaped core)
71a Base 71b, 71c Column 72 Second core 72a Base 72b Expanded core 73 Insulating material A (fills gap) Winding formation region

Claims (7)

A primary winding;
A multilayer board formed by laminating a plurality of boards each having a spiral conductive pattern constituting the secondary winding formed on the main surface; and
A core body that forms a magnetic path between the primary winding and the secondary winding; and the secondary winding that extends from the core body along the main surface of the multilayer substrate. A core having an extended core portion covering at least a part of the winding forming region formed with
A thin transformer comprising:   The thin transformer according to claim 1, wherein the extended core portion of the core covers the entire winding forming region.   The secondary winding is composed of one or a plurality of electrically connected conductor patterns, and generates a first secondary voltage, and the first secondary winding. A second secondary winding that is configured from one or a plurality of electrically connected conductor patterns that do not constitute a secondary winding and that generates a second secondary voltage; The thin transformer according to claim 1 or 2.   Of the conductor pattern constituting the first secondary winding and the conductor pattern constituting the second secondary winding, the lengths of the portions covered by the extension core portion are different from each other. The thin transformer according to claim 3. The primary winding is composed of a conductive wire wound around a cylindrical portion of a bobbin,
The core includes a first base portion disposed on a lower surface side of the multilayer substrate, a first pillar portion standing from the first base portion and inserted into the cylindrical portion of the bobbin, and the first pillar portion. A first core including a second pillar portion inserted through a through-hole penetrating the multilayer substrate in a region standing from a base and surrounded by the conductor pattern; and disposed on an upper surface side of the multilayer substrate 5. The thin transformer according to claim 1, further comprising: a second base portion and a second core including the extended core portion provided integrally with the second base portion. One end of the multilayer substrate is provided with a cutout portion larger than the planar shape of the bobbin,
The thin transformer according to claim 5, wherein the bobbin is accommodated in the cutout portion so as not to contact the multilayer substrate and to be disposed in the same plane as the multilayer substrate.   The thin transformer according to claim 1, wherein the core is made of ferrite.

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