JPH10163039A - Thin transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably improve magnetic coupling, loss, and temperature rise of a thin transformer having an auxiliary coil. SOLUTION: A multilayer printed coil substrate formed by laminating a primary coil pattern 2 and a secondary coil pattern with an insulation layer in between. A thin transformer is formed by building a magnetic core on the multilayer printed coil substrate. An auxiliary coil pattern 4 is formed on the same face as at least one of the laminated face having a primary coil pattern 2 or having a secondary coil pattern.

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 electronic equipment and a power supply, and more particularly to a thin transformer suitable for use in a converter circuit for a switching power supply.

[0002]

2. Description of the Related Art With the recent miniaturization of switching power supplies, power supply transformers and choke coils are also required to be thinner and have higher frequencies. In order to respond to such demands, a thin transformer composed of a laminated coil made of a multilayer printed coil board by laminating printed wiring insulating materials, and a magnetic core such as a ferrite core assembled to the laminated coil has been developed. Various types of transformers have been used in place of transformers using winding wires.

[0003] This type of laminated coil is formed by laminating an insulating layer of a required thickness between coil patterns and connecting the terminals of each coil pattern to form a winding.
It is known that such a laminated coil component has a high current density, is easy to be thin, and can obtain a transformer having a high degree of magnetic coupling between the primary and the secondary by increasing the number of layers. .

FIG. 10 shows a conventional example of a laminated structure of a transformer comprising such a multilayer printed coil board.
This shows a configuration similar to that disclosed in Japanese Patent No. 17658, and an insulating material 1 made of an insulating sheet or an insulating plate.
A primary coil pattern 2, a secondary coil pattern 3, or an auxiliary coil pattern 4 is formed on both sides of the substrate (the coil pattern on the back surface of the insulating material 1 is not shown in FIG. 10), and these coil patterns 2, 3, or 4 are formed. Through holes 12 and 13 penetrating the inner end and the insulating material 1 are provided, and a conductor is fixed to the inner walls of the through holes 12 and 13 by plating so that the inner ends of the coil patterns 2, 3 and 4 on the front and back sides are connected to each other. Connected. Reference numeral 6 denotes a pad formed on the front and back edges of the insulating material 1.

[0005] The coil patterns 2, 3 or 4 formed on the front and back surfaces of the insulating material 1 as described above are referred to as one coil unit a, b, c, as shown in the configuration diagrams of FIG. 10 and FIG. In addition, an insulating material 7 made of an insulating sheet or an insulating plate is interposed between each primary coil unit a, the secondary coil unit b, and the auxiliary coil unit c, for example, via an adhesive provided on the insulating material 7. Then, a through hole 9 for inserting the magnetic core 8 is opened, a through hole 10 for passing a terminal is provided in the pad 6, and the through hole 10 corresponding to the laminating direction is plated. And connect.

[0006]

The auxiliary coil constituted by the auxiliary coil pattern 4 is mainly used for purposes such as a power supply for driving an integrated circuit constituting a control circuit and the like and a voltage detection. This winding does not participate in the magnetic coupling between the primary side and the secondary side. In general, the current of the auxiliary coil may be small, but in the conventional example, at least one coil unit is required. If the number of coil units is the same, the primary coil pattern 2 and the secondary coil Since the number of layers of the pattern 3 is reduced, the number of opposing surfaces of the primary coil pattern 2 and the secondary coil pattern 3 is reduced, leading to an increase in leakage inductance and a winding between the primary coil pattern and the secondary coil pattern. The loss increases due to the increase in resistance, and problems such as heat generation have occurred.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a thin transformer having an auxiliary coil, which has a magnetic coupling, a loss,
It is an object of the present invention to provide a configuration that can significantly improve a temperature rise.

[0008]

According to the present invention, there is provided a multilayer printed coil substrate comprising a primary coil pattern and a secondary coil pattern laminated with an insulating layer interposed therebetween. In a thin transformer in which a magnetic core is assembled to the multilayer printed coil substrate,
An auxiliary coil pattern is formed on the same surface as at least one of the laminated surface on which the primary coil pattern is formed or the laminated surface on which the secondary coil pattern is formed. 1).

The thin transformer according to the present invention is characterized in that the auxiliary coil pattern is formed between the primary coil patterns or between the secondary coil patterns on the same plane as the lamination surface. Claim 2).

[0010]

In the first aspect, since the auxiliary coil pattern is formed on the same lamination surface as the primary coil pattern or the secondary coil pattern (that is, the main coil pattern), it is necessary to configure the auxiliary coil as one coil unit. The number of layers of the primary side coil or the secondary side coil can be increased by that amount, so that the magnetic coupling can be increased. Also, the auxiliary coil pattern can be a thin pattern, and the width of the main coil pattern is almost Since the number of layers is not reduced, the winding resistance is reduced by the increase in the number of layers, thereby making it possible to significantly reduce the loss and the temperature rise.

In the second aspect, since the auxiliary coil pattern is provided between the main coil patterns, the inner peripheral side of the coil pattern becomes the main coil pattern, and the auxiliary coil pattern is provided on the inner peripheral side of the main coil pattern. The primary and secondary bonds are better in comparison. Further, compared to the case where the auxiliary coil pattern is limited to the inner side or the outer side of the main coil pattern, the limitation on the number of turns of the auxiliary coil pattern is eased.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing one coil unit of one embodiment of the thin transformer of the present invention. FIG. 2A is a perspective view showing the thin transformer of this embodiment before assembling a core and a multilayer printed coil board. 2B is a perspective view showing the completed product, FIG. 3 is a configuration diagram of the thin transformer, FIG. 4 is a perspective view showing a laminated structure of the thin transformer, and FIG. 5 is a single insulating material in the present embodiment. 5 is an exploded perspective view showing an example of a coil pattern on the front and back surfaces of FIG.

As shown in FIGS. 1 and 3 to 5, in this embodiment, an auxiliary coil pattern 4 is formed between primary coil patterns 2. As shown in FIG. 5, these coil patterns 2, 4 are formed on both back surfaces of the insulating material 1,
The outer end of the primary coil pattern 2 on the upper surface of the insulating material 1 is a pad 6a in the first row, and the inner end 2a is inside the primary coil pattern 2 on the lower surface via the conductor in the through hole 12 opened in the insulating material 1. Connected to the end 2b, the through hole 2 on the lower surface
Is connected to a pad 6d in a fourth row different from the pad 6a.

The outer end of the auxiliary coil pattern 4 on the upper surface of the insulating material 1 in FIG. 5 is connected to the second row of pads 6b, and the inner end 4a is connected to the through-hole 1 provided in the insulating material 1.
The inner end 4b of the auxiliary coil pattern 4 on the lower surface of the insulating material 1 is connected to the inner end 4b of the auxiliary coil pattern 4 on the lower surface of the insulating material 1 via the inner conductor 3, and the outer end of the auxiliary coil pattern 4 on the lower surface is connected to the pads 6c in the third row.

As shown in FIGS. 3 and 4, in this embodiment, the auxiliary coil pattern 4 and the primary coil pattern 2
Are formed on the front and back surfaces of the insulating material 1, two primary units a are provided, and two secondary units b having the secondary coil patterns 3 formed on the front and back surfaces are also provided. 6e, 6f
Is a pad for the auxiliary coil pattern 4, 6g is a pad for the primary coil pattern 2, and 6h and 6i are pads for the secondary coil pattern 3. The primary unit a and the secondary unit b are laminated by bonding or welding via an insulating material 7 to form a multilayer printed coil board 14 shown in FIG. The substrate 14 is provided with a through hole 9 for inserting the magnetic core 8, and the pads 6a to 6i are provided with through holes 10 for passing terminals, and the through holes 10 corresponding to the laminating direction are plated. Connecting.

The magnetic core 8 includes E-type cores or E-type cores.
A combined structure of the mold core and the I-shaped core is adopted, and the middle leg of the E-shaped core is inserted into the through hole 9. As shown in FIG. 2B, terminals 15 are inserted into through holes 10 provided in the pads 6a to 6i, and a tape 16 is wound around the outer periphery of the magnetic core 8 to obtain a product.

As described above, in the present embodiment, since the auxiliary coil pattern 4 is formed on the same lamination surface as the primary coil pattern 2, it is not necessary to configure the auxiliary coil as one coil unit, and accordingly, the multi-layer printing is performed. When the thickness of the coil substrate 14 is the same, the number of the primary side coils or the number of the secondary side coils can be increased, so that the facing area thereof is also increased, and the magnetic coupling can be increased. In the present embodiment, as can be seen from a comparison between FIG. 3 and FIG. 11, an example is shown in which the number of secondary units b is increased by one (ie, two secondary coils). Thus, the DC resistance and the AC resistance of the secondary coil can be reduced to approximately half that of the conventional case.

Since the auxiliary coil pattern 4 has a small current flowing through the auxiliary coil pattern 4, it can be a thin pattern as shown in the figure. Therefore, the width of the primary coil pattern 2 is hardly reduced. The DC resistance of the coil is not so large, and as a result, the winding resistance is reduced by the increase in the number of layers, thereby making it possible to greatly reduce the loss and the temperature rise.

The arrangement of the primary coil pattern 2 and the auxiliary coil pattern 4 can be variously changed according to the required number of turns and the like. 6 to 9 are exploded perspective views showing examples of combinations of these patterns for the patterns on the front and back surfaces of the insulating material 1, respectively. The example of FIG. 6 is an example in which the primary coil has three turns and the auxiliary coil has one turn. 7, the example of the primary coil has three turns and the auxiliary coil has three turns, the example of FIG. 8 has the primary coil of three turns, the auxiliary coil has two turns, and the example of FIG. This is an example in which the side coil has three turns and the auxiliary coil has five turns.

When the auxiliary coil pattern 4 is formed on the same plane as the primary coil pattern 2 or the secondary coil pattern (main coil pattern), the auxiliary coil pattern 4 is formed only on the outer or inner circumference of the main coil patterns 2 and 3. Although it is conceivable to provide the auxiliary coil pattern 4 between the main coil patterns as shown in the above embodiments, the auxiliary coil pattern 4 is provided on the inner peripheral side of the main coil pattern as compared with the case where the auxiliary coil pattern 4 is provided on the inner peripheral side of the main coil pattern. The main coil pattern can be close to the core, and the magnetic coupling is improved. In addition, as compared with the case where the auxiliary coil pattern 4 is limited to the inner peripheral side or the outer peripheral side of the main coil patterns 2 and 3, the restriction on the number of turns is relaxed.

In the above embodiment, the example in which the auxiliary coil pattern 4 is formed on the same surface as the lamination surface of the primary coil pattern 2 is shown, but the auxiliary coil pattern 4 is formed on the same surface as the secondary coil pattern 3. Alternatively, the auxiliary coil pattern 4 may be provided on the same plane as the laminated surface of both the primary coil pattern 2 and the secondary coil pattern 3. Also,
In the above embodiment, the example in which the coil patterns 2 and 3 are formed on both surfaces of the insulating material 1 has been described, but one of the coil patterns 2 and 3 is formed on one surface of each insulating material 1 and laminated. Is also good.

[0022]

According to the first aspect of the present invention, in a thin transformer using a multilayer printed coil board, at least one of a laminated surface on which a primary coil pattern is formed and a laminated surface on which a secondary coil pattern is formed. Same as
Since the auxiliary coil pattern is formed, the number of layers of the primary side coil or the secondary side coil can be increased, so that the magnetic coupling can be increased and the auxiliary coil pattern needs to be a thin pattern, and the width of the main coil pattern Is hardly reduced, so that the winding resistance can be reduced by the increase in the number of layers, whereby loss and temperature rise can be significantly improved.

According to the second aspect, since the auxiliary coil pattern is provided between the main coil patterns, the inner peripheral side of the coil pattern becomes the main coil pattern, and the auxiliary coil pattern is provided on the inner peripheral side of the main coil pattern. , Primary and secondary bonds are better. In addition, as compared with the case where the auxiliary coil pattern is limited to the inner side or the outer side of the main coil pattern, the restriction on the number of turns is relaxed.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of a thin transformer of the present invention for one coil unit.

FIG. 2A is a perspective view showing the thin transformer of the present embodiment before assembling a core and a multilayer printed coil board, and FIG.
Is a perspective view showing the finished product.

FIG. 3 is a configuration diagram of a thin transformer of the present embodiment.

FIG. 4 is a perspective view showing a laminated structure of the thin transformer of the embodiment.

FIG. 5 is an exploded perspective view showing an example of a coil pattern on the front and back surfaces of one insulating material in the embodiment.

FIG. 6 is an exploded perspective view showing another example of the coil pattern on the front and back surfaces of one insulating material according to the present invention.

FIG. 7 is an exploded perspective view showing another example of the coil pattern on the front and back surfaces of one insulating material in the present invention.

FIG. 8 is an exploded perspective view showing another example of the coil pattern on the front and back surfaces of one insulating material in the present invention.

FIG. 9 is an exploded perspective view showing another example of the coil pattern on the front and back surfaces of one insulating material in the present invention.

FIG. 10 is a perspective view showing a laminated structure of a conventional thin transformer.

FIG. 11 is a configuration diagram of a conventional thin transformer.

[Explanation of symbols]

1: Insulating material, 2: Primary coil pattern, 3: Secondary coil pattern, 4: Auxiliary coil pattern, 6a to 6i:
Pad, 7: insulating material, 8: magnetic core, 9: through hole, 1
0, 12, 13: through hole, 14: multilayer printed coil board, 15: terminal, 16: tape

Claims (2)

[Claims] 1. A thin transformer comprising a multilayer printed coil board formed by laminating a primary coil pattern and a secondary coil pattern with an insulating layer interposed therebetween, and a magnetic core assembled to the multilayer printed coil board. The thin type characterized in that an auxiliary coil pattern is formed on the same surface as at least one of the laminated surface on which the primary coil pattern is formed or the laminated surface on which the secondary coil pattern is formed. Trance. 2. The thin transformer according to claim 1, wherein the auxiliary coil pattern is formed between primary coil patterns or secondary coil patterns on the same plane as the lamination surface.