JPH1022139A - Planar transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a planar transformer in which conductors are buried so that terminal sections are easily connected and hardly short circuits and the transformer can be easily fixed to a circuit board, etc., by forming the terminal sections in rigid bodies. SOLUTION: A primary planar coil 40 and a secondary planar coil are housed in the housing sections of substrates 31 and 33 made of a magnetic material in a laminated and mutually insulated state and at least one side of the primary and secondary coils is composed of a plurality of conductors. In addition, an inlet section and outlet section reaching the primary or secondary coil housed in the housing section are formed on the external surface of the substrates 31 and 33 and parts of the coils are arranged at the inlet section and outlet section. Moreover, conductive paste 45 is put in each inlet section and outlet section and a terminal 53 is inserted into each inlet section and outlet section, with its outer end section on the outside of the substrates. Furthermore, each inserted terminal is electrically connected to the terminal section of each planar coil in the substrates through the paste 45.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for making a connection terminal portion special in a specially-shaped flat transformer capable of realizing miniaturization and thinning.

[0002]

2. Description of the Related Art In recent years, there has been a demand for smaller and thinner electronic devices as seen in the spread of portable information devices, and the demand for smaller and thinner power supply circuits incorporated in these devices has been increasing. However, it is particularly important to reduce the size and thickness of magnetic elements such as transformers and inductors. Conventionally,
In a transformer mounted on an electronic device of this type, a primary winding and a secondary winding are formed on a magnetic core made of an annular magnetic material formed by winding a thin strip of an amorphous alloy or the like manufactured by a quenching method. A transformer provided with a toroidal core having an applied configuration, or a central portion of an E-type magnetic body with respect to a magnetic core (EI core-type magnetic core) in which an E-type magnetic body and an I-type magnetic body are combined. There is known a transformer having a configuration in which a winding is provided.

However, as electronic devices have become smaller and thinner, transformers having a height of several mm have been required.
In a transformer having a conventional toroidal core, if the annular magnetic body is formed thin, the strength of the magnetic body itself becomes insufficient, which may cause a problem in strength. When forming a magnetic body, there is a limit to the width of the ribbon that can be manufactured, and the width of the ribbon limits the thickness of the annular magnetic body. However, there is a problem that the number of windings that can be applied to such a thin magnetic body is also limited. Next, in an EI core type magnetic core in which an E-type magnetic material and an I-type magnetic material are combined, the E-type magnetic material and the I-type magnetic material are overlapped, so that the entire thickness is required to some extent, In addition to this, the thickness of the winding portion is added, so that it is difficult to reduce the overall thickness to several mm.
In addition, conventional transformers and inductors with exposed coil windings emit unnecessary high-frequency electromagnetic fields and cause electromagnetic noise, as well as ICs and other devices on the same motherboard on which these transformers and inductances are mounted. It also caused a malfunction.

[0004] Both the transformer having the toroidal core and the transformer using the EI core need to be housed in a resin bobbin. When the core is housed, the heat generated inside the transformer is accumulated in the resin coating and the resin bobbin, and the heat cannot be efficiently radiated to the outside. Therefore, there is a problem that the entire magnetic core is easily overheated. Furthermore,
In the EI core shape, there is a problem of an increase in iron loss due to concentration of magnetic flux, and an increase in copper loss due to interlinking of a magnetic flux with a copper wire.
There is also a disadvantage that heat concentration points are generated due to the structure of the EI core.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present applicant has proposed a plane transformer having a completely novel configuration which has not been known hitherto and which can solve the above-mentioned various problems on January 30, 1996. A patent application is filed in Japanese Patent Application No. 8-14653. The planar transformer A according to this patent application is:
As shown in FIGS. 8 and 9, a base 1 made of a plate-shaped magnetic material containing a planar coil, a gap insulating layer 2 attached on the upper surface of the base 1, and It is mainly composed of a planar substrate 3 made of a magnetic material adhered thereto. The magnetic material constituting each of the base 1 and the base 3 is made of a magnetic material having high electric resistance and high magnetic permeability such as Ni—Zn ferrite or Mn—Zn ferrite, and the gap insulating layer 2 is made of an insulating resin. It is composed of film.

[0006] On the upper surface of the base 1, there is formed a storage section 5 formed in a plane substantially skewed shape or a substantially comb blade shape.
, The secondary planar coils 8, 8, the main insulating layer 9, and the primary planar coil 10 having the same planar shape as the storage section 5 are sequentially stored from the upper side in a stacked state. Also, each secondary planar coil 8
Is formed by covering a film conductor 12 with a resin insulating film 13, and each primary planar coil 10 is
Is covered with a resin insulating film 15. Then, the film conductor 12 of the lower right secondary planar coil 8 shown in FIG.
And the film conductor 12 of the upper left secondary planar coil 8 are electrically connected by a connection line 18, the lead wire 20 is connected to the film conductor 12 of the upper right secondary planar coil 8, and the lower left The lead wire 21 is connected to the film conductor 12 of the secondary planar coil 8, and the lead wire 22 is connected to the film conductor 14 of the right primary planar coil 10, and connected to the film conductor 14 of the left primary planar coil 10. Leader 23
Are connected, a second terminal on the secondary winding side is formed by the lead wires 20 and 21, and a first terminal on the primary winding side is formed by the lead wires 22 and 23, respectively.

According to the above configuration, an output voltage ratio of 1: 2 can be obtained between the primary side and the secondary side. Further, according to the above configuration, the magnetic material constituting the bases 1 and 3 is made of a material having a high magnetic permeability, and the magnetic material having a high magnetic permeability is arranged in the vicinity of the planar coil. Is increased, the current density in the planar coil is made uniform, and local heat generation in the planar coil can be avoided. Further, when the bases 1 and 3 are made of the above-described magnetic materials, they have excellent thermal conductivity, so that the heat generated inside can be efficiently released to the outside.

By the way, in order to connect and fix the above-structured flat transformer to a circuit board or the like, as shown in FIG.
6, 27 and 28 need to be soldered, but the flat transformer is extremely thin with a thickness of several mm, the distance between the connection parts is small, and the film conductor is flexible and easy to move. In addition, there is a possibility that the film conductor may move during the soldering of the lead wire to short-circuit the soldered portion. In addition, when attaching a planar coil in a state where leads are connected to a flexible film conductor to a circuit board, it is difficult to fix the planar coil itself to the board because the film conductor is in a bent state. There was a problem.
Further, in the connection state shown in FIG. 10, there is a problem that the appearance of the connection portion is extremely poor.

The present invention has been made in view of the above circumstances, and has a novel configuration which is completely different from a conventional toroidal type transformer or the like. It is an object of the present invention to provide a planar transformer in which a soldered portion is configured to be hard to move by being made of a rigid body, connection is easy, a short circuit is unlikely to occur, and the whole is easily fixed to a circuit board or the like.

[0010]

According to the first aspect of the present invention, a housing is formed on a base made of a magnetic material, and a primary planar coil and a secondary planar coil are formed in the housing. An inlet for receiving at least one of the primary planar coil and the secondary planar coil composed of a plurality of conductors in a state of being insulated from each other, and reaching the primary planar coil of the accommodating portion in the base on the outer surface of the base; An outlet portion and an inlet portion reaching the secondary planar coil are formed, respectively, and a part of each planar coil is arranged at each of the inlet portion and the outlet portion, while a conductive paste is applied to each of the inlet portion and the outlet portion. A terminal made of a rigid body that is arranged inside and the outer end is out of the base is inserted,
Each of the inserted terminals is electrically connected to a terminal portion of each planar coil in the base via a conductive paste.

In the present invention, it is preferable that the conductive paste is inserted into an inlet and an outlet by screen printing. Next, it is preferable that the terminal portion of the primary planar coil and the terminal portion of the secondary planar coil are led out from the base in a direction intersecting with each other. Further, it is preferable that a resin insulating layer is formed at least inside the housing portion of the base. On the other hand, in the configuration described above, the outlet portion and the inlet portion of the primary planar coil are provided adjacent to each other on one surface of the base, and the outlet portion and the inlet portion of the secondary planar coil are provided at the outlet portion of the primary planar coil. And a terminal portion of the primary planar coil and a terminal portion of the secondary planar coil are led out in a direction crossing each other on the other two surfaces adjacent to the surface provided with
It is preferable that the secondary planar coil has a multilayer coil structure in the housing portion of the base. Next, each of the planar coils may have a two-layer structure of an insulating sheet and a conductive sheet. Further, the base may be divided into two parts in the thickness direction to form a storage portion in at least one base, and the divided base may be covered with a resin insulating layer.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 7 show a first example of a planar transformer according to the present invention. In this example, a planar transformer B includes a base 31 made of a plate-shaped magnetic material in which a planar coil described later is housed, and It is mainly composed of a flat base 33 made of a magnetic material adhered on the base 31. The magnetic material constituting the base 31 and the base 33 is N
It is made of a magnetic material having high electric resistance and high magnetic permeability, such as i-Zn ferrite and Mn-Zn ferrite.

Further, the magnetic material constituting the bases 31, 33 preferably has a magnetic permeability of 200 or more at 1 MHz, more preferably 1000 or more at 1 MHz. This is because, as will be described later, a magnetic material having a high magnetic permeability is arranged near the planar coil to increase the inductance of the outer peripheral portion of the planar coil, make the current density in the planar coil uniform, and generate local heat in the planar coil. In order to avoid this, the base 31 and the base 3
If the magnetic permeability of the magnetic material constituting 3 is low, the rate at which the planar coil generates heat is undesirably increased. The base 3
1 or base 33 made of Ni-Zn ferrite, Mn-Zn
When made of a magnetic material having a high electric resistance and a high magnetic permeability such as ferrite or the like, since these are also excellent in thermal conductivity, the flat coil portion or the base 31 or the base 33 can be used.
The heat generated in the above can be efficiently released to the outside.

Next, a resin insulating layer 34 is formed on the entire inner and outer surfaces of the base 31 and the base 33. The resin used here is preferably a resin having a dielectric constant as small as possible. Specifically, polyimide resin, polyvinyl chloride, polystyrene, polypropylene, polyethylene, polycarbonate, polyester, polytetrafluoroethylene, fluororesin, polyethylene terephthalate, tetra Excellent heat resistance from fluoroethylene, nylon, epoxy resin,
One or more materials having excellent mechanical strength can be appropriately selected and used. Each of these resins has a relative dielectric constant of 2
Although it is sufficiently low in the range of ~ 4 and can be applied to the structure of the present invention, a laminated structure of two or more layers may be used in order to secure heat resistance and mechanical strength or a sufficient thickness.

As shown in FIG. 3, a groove-shaped storage portion 35 formed in a plane inverted U-shape is formed on the upper surface 31a of the base 31 so as to open to the upper surface 31a and the front surface 31b of the base 13. The front surface 3 on the upper surface 31a of the base 31.
In a portion near 1b, an auxiliary storage portion 36 in the form of a straight groove extending in a direction crossing the storage portion 35 having a flat inverted U shape and reaching both side surfaces 31c of the base 31 is formed. Portions of the front surface 31b of the base 31 where both ends of the storage portion 35 are opened are an inlet portion 37 and an outlet portion 38 of the storage portion 35, and the ends of the auxiliary storage portion 36 are provided on both side surfaces 31c of the base 31. The opened portions are the inlet portion 39A and the outlet portion 39 of the auxiliary storage portion 36.
B.

Next, an inverted U-shaped primary planar coil 40 is housed at the bottom of the inverted U-shaped storage section 35 as shown in FIG. The primary planar coil 40 is a planar inverted U-shaped insulating sheet 4 made of an insulating material made of polyimide or the like.
The first flat coil 40 has both ends 40A, 40A disposed inside the entrance portion 37 and the exit portion 38 of the storage portion 35. It is arranged at the bottom of the storage section 35. And the storage unit 3
5, terminals 43 and 44 made of a rigid body such as a tongue-shaped metal are connected to the conductive paste 45 at the entrance 37 and the exit 38, respectively.
The terminals 43, 44 and the copper sheet 42 of the primary planar coil 40 are respectively connected to the conductive paste 45.
Are electrically connected to each other. The terminals 43 and 44
Is made of a rigid body and can be made of any material as long as it has electrical conductivity.It is composed of either a metal terminal or a conductive terminal formed by forming a conductive film such as plating on the outer surface of a tongue piece made of a rigid body such as ceramic. Is done.

Next, a secondary planar coil 46 shown in FIG. 7 is stored above the primary planar coil 40 in the storage section 35. This secondary planar coil 46 is formed by electrically joining a lower coil 47 shown in FIG. 5 and an upper coil 48 shown in FIG. 6 and laminating them as a double coil as shown in FIG.

First, as shown in FIG. 5, the lower coil 47 includes an inverted U-shaped main body portion 47a which can be stored in the storage portion 35,
The auxiliary storage portion 36 is provided at one end of the main body portion 47a.
Extension 47 projecting to the side of the main body 47a along
b and the auxiliary storage 3 at the other end of the main body 47a.
The main body 47a and the extending portion 47b are provided with an upper surface of a copper sheet (conductive sheet) 47A as shown in FIG. It is configured to be covered with an insulating sheet 47B made of polyimide or the like, and the copper sheet 47A is exposed by removing the insulating sheet 47B at the extension 47c.
In order to improve the electrical connection with the upper coil 48 described later, a connection pad 47A 'made of a conductor may be provided on the exposed copper sheet portion. Next, as shown in FIG. 6, the upper coil 48 includes an inverted U-shaped main body portion 48a that can be stored in the storage portion 35, and the main body portion 48a.
An extension 48b protruding toward the right side of the main body portion 48a along the auxiliary storage portion 36 at a left end portion of the main body portion 48a, and protruding rightward along the auxiliary storage portion 36 at a right end portion of the main body portion 48a. The main body portion 48a, the extending portion 47b, and the extending portion 48c each have a top surface of a copper sheet (conductive sheet) 48A made of polyimide or the like, as shown in FIG. And an insulating sheet 48B.

According to the above configuration, the lower coil 47 and the upper coil 48 are overlapped with each other, and
The conductive sheet 47A of the extension 47c of the lower coil 47 and the extension 4 of the upper coil 48
The secondary planar coil 46 can be formed by overlapping and electrically connecting the copper sheets 48A on the lower surface side of the lower coil 8b, and the conductive sheet 4 of the extension 47b of the lower coil 47 can be formed.
A double coil is configured in which the 7A portion is a terminal on one input side and the conductive sheet 48A portion of the extension 48c of the upper coil 48 is an output terminal on the other side. The connecting portion between the upper coil 47 and the lower coil 48 may be either an exposed portion of the copper sheet 47A or a copper sheet 48A when the coils 47 and 48 are overlapped.
It is preferable that a conductive adhesive is applied to the lower surface of the tip portion to ensure connection.
Also, the connection pad 47A 'is provided on the exposed portion of the copper sheet 47A.
Is provided, the lower coil 47 and the upper coil 48 are reliably connected via the connection pad 47A '.

Next, a metal terminal 51 is fitted into the entrance portion 39A of the auxiliary storage portion 36 of the base 35 via a conductive paste 50, and the metal terminal 51 is connected to the extension portion 47 of the lower coil 47.
b, is electrically connected to the conductive sheet via the conductive paste 50, and a metal terminal 53 is fitted into the outlet portion 39B of the auxiliary storage portion 36 via the conductive paste 52. Extension 48c of coil 48
Is electrically connected to the conductive sheet 48A through a conductive paste 52.

In the above structure, the groove-shaped storage portion 3 is formed.
The depth of 5 and 36 depends on the primary planar coil 40 accommodated therein.
And the total thickness of the secondary planar coil 46 is preferably approximately equal to the total thickness. In this way, when the base 33 is adhered to the base 31, both coils 40 and 46 are connected to the base 31, 3
3 and can be fixed. In addition, the lower coil 47 and the upper coil 4 simultaneously forming the secondary planar coil 46
8 are in close contact with each other, so that the extension 4
7c copper sheet 47A portion and extension 4 of upper coil 48
8b copper sheet 48A portion can be crimped and both coils 47,
Forty-eight electrical connections can be made well.

Next, the entrance 37 of the front surface 31b of the base 31
It is preferable that the terminals 43 and 44 be fixed by inserting an insulating sheet above the portion where the terminals 43 and 44 are inserted in the outlet portion 38 and filling the gap with an adhesive. Also, a block 31B made of the same magnetic material as the base 31 is used.
May be inserted. Further, the thickness of the terminals 43 and 44 is formed thick inside the inlet portion 37 and the outlet portion 38,
The thickness of the terminals 43 and 44 may be made thinner outside the outlet 38 and the thickness of the terminals 43 and 44 may be used to fill the gap.

The flat transformer B uses the terminals 43 and 44 as lead wires for the primary winding, and the terminals 51 and 53 as lead wires for the secondary winding. It can be used as a transformer with an output ratio of 2. Further, the substrates 31 and 33 of this example are made of Ni—Zn ferrite, Mn—Z
Made of magnetic material with high electric resistance and high magnetic permeability, such as n-ferrite, has excellent thermal conductivity. Since heat can be quickly discharged to the outside via the bases 31 and 33, unlike a resin bobbin storage type transformer having a conventional structure, there is little risk of accumulating heat in a planar coil.

Next, since both the primary planar coil 40 and the secondary planar coil 46 are formed in a sheet shape, the thickness can be reduced, so that the planar transformer B having a thickness of several mm as a whole is formed. , The sheet-shaped planar coils 40 and 46 have a height of about several mm.
Can easily be stacked, and the output ratio between the primary planar coil and the secondary planar coil is not 1: 2 as in this example, but 1: n
To the desired ratio. That is, for example, an output ratio of 1: 3 can be obtained by connecting three coils of a sheet-like secondary planar coil in a laminated coil structure and three sheets of a secondary planar coil. By connecting in series as a structure, an output ratio of 1: 4 can be obtained.

In the structure of the present invention, the resin insulating layer 34
Is provided, the resin insulating layer 34 forms a gap between the bases 31 and 33.
4 is provided and the resin insulating layer 3 is not provided.
It is thought that the case where no 4 is provided is slightly advantageous in terms of magnetic coupling and efficiency. However, the resin insulating layer 3
If the configuration without 4 is used, the magnetic flux tends to be concentrated near the coil where the exciting current exists because the closed magnetic circuit configuration is likely to occur, and heat generation due to local magnetic saturation and concentration of iron loss becomes a problem. It may be preferable to provide layer 34. That is, since the magnetic resistance is high in the portion of the resin insulating layer 34, the magnetic flux density distribution in the bases 31 and 33 made of a magnetic material becomes uniform.

Next, an example of a method for manufacturing the planar transformer B having the above configuration will be described. In order to manufacture the planar transformer B of this example, a base 31 and a base 33 made of a high magnetic permeability magnetic material such as Ni—Zn ferrite are manufactured as shown in FIG. The coil 40, the lower coil 47, and the upper coil 48 are sequentially stacked and housed, and then the base 33 is bonded to the upper surface of the base 31. In this state, holes corresponding to the inlet 37 and the outlet 38 are formed on the front surface 31b side of the base 33, and holes corresponding to the inlet 39 and the outlet 40 are formed on both side surfaces 31c of the base 33. Therefore, a conductive paste is provided in the openings of these holes by a screen printing method, and then the terminals are pushed in from the respective openings to push the conductive paste into the inner side of each hole, and the primary paste located inside each hole is pressed. The terminal can be attached by allowing the conductive paste to reach the end of the planar coil 40 or the end of the secondary planar coil 46.

The terminal 4 fitted and fixed in each hole of the base 33
Since 3, 44, 51, and 53 are fixed and held by the base 33, there is little risk of bending or movement. Therefore, when connecting the planar transformer B of this example to a circuit board or the like, the terminal 4
The connection cords can be easily soldered to 3, 44, 51, and 53, and there is little risk of short-circuiting the connection portion during soldering. Also, the terminal 4 on the primary planar coil side
Since the terminals 3 and 44 are provided on the front side 31b of the base 31 and the terminals 51 and 53 of the secondary planar coil are separately provided on the side surface 31c of the base 31, a sufficient distance between the terminals can be secured. Thus, occurrence of a short circuit at the time of soldering can be prevented.

[0028]

As described above, according to the present invention, the primary planar coil and the secondary planar coil are accommodated in the accommodating portion of the base made of a magnetic material, and the conductive paste is provided at the entrance and the exit provided on the outer surface of the base. By arranging the rigid terminal via the terminal, the terminal can be exposed to the outside of the base, and the connection can be performed using the rigid terminal. Therefore, the possibility that the terminals move during soldering for terminal connection and the soldering becomes difficult is reduced, and the risk of a short circuit accident during soldering can be reduced. Also, since the terminal portion does not move, the soldered portion does not move, and there is no possibility of contact with other lines of the attached circuit board, so that a short circuit with the outside hardly occurs. Furthermore, by soldering a terminal made of a rigid body protruding from the base to the circuit board, the base can be easily fixed to the circuit board, and a flat transformer can be provided that can have a strong mounting structure.

Next, in the present invention, an inlet and an outlet for the primary planar coil are provided on one surface of the base, and respective terminals are provided on this one surface, and an inlet for the secondary planar coil is provided on the other surface of the base. Alternatively, if the outlet is provided and each terminal is provided on another surface, even in the case of a thin planar transformer, the position where the terminal is provided can be provided at a sufficient interval around the base, and As a result, a large distance between adjacent terminals can be ensured, so that the occurrence of a short circuit at the time of connection by soldering can be suppressed.

Further, by forming at least one of the primary plane coil and the secondary plane coil from a plurality of conductors, the number of turns of the primary side coil and the number of turns of the secondary side coil can be changed. Accordingly, it is possible to provide a flat transformer capable of setting an output voltage to a desired ratio. Further, since the primary planar coil and the secondary planar coil are housed in a base made of a magnetic material, a transformer having almost no electromagnetic noise radiation can be obtained.
Since a magnetic material having high magnetic permeability can be arranged near the next planar coil, the inductance at the outer peripheral portion of each planar coil can be increased, and the current density in the planar coil conductor portion can be made uniform when energized. Thus, it is possible to provide a planar transformer that generates less Joule heat in the planar coil portion. Further, since the primary and secondary planar coils are housed in the housing portion of the base, the overall structure is characterized in that it can be made thinner and smaller.

Further, according to the present invention, a gap between the substrates is formed by dividing the substrate into two parts in the thickness direction, forming a housing portion for a planar coil on at least one of the substrates, and coating the surface of the substrate with a resin insulating layer. This makes it possible to increase the magnetic resistance of the resin insulating layer serving as a gap to make the magnetic flux distribution uniform between one base and the other base, thereby making it possible to form a primary plane. Since the magnetic flux generated by the coil and the secondary planar coil is homogenized around the planar coil and the magnetic flux can be prevented from being concentrated on a part of the planar coil, it is possible to prevent the planar coil from partially generating excessive heat. Therefore, it is possible to provide a planar transformer having high thermal efficiency without the possibility that the planar coil is melted by heat generation. Furthermore, the base is made of a magnetic material, and the primary and secondary planar coils are housed therein. Compared with the conventional structure in which the coil is housed in a resin bobbin, the coil is covered. The thermal conductivity of the base is higher than that of the resin bobbin,
Even if heat is generated in the planar coil portion, the heat can be quickly released to the outside through the base. Therefore, it is possible to provide a flat transformer in which heat is hardly stored.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first example of a planar transformer according to the present invention.

FIG. 2 is a sectional view showing a part of the planar transformer shown in FIG. 1;

FIG. 3 is an exploded perspective view showing a base of the transformer.

FIG. 4 is a plan view of a base and a primary planar coil of the planar transformer.

FIG. 5 is a plan view of a base and a lower coil of the planar transformer.

FIG. 6 is a plan view of a base and an upper coil of the transformer.

FIG. 7 is a perspective view of an upper coil and a lower coil constituting a secondary planar coil.

FIG. 8 is an exploded perspective view of the previously proposed planar transformer.

FIG. 9 is a front view of the planar transformer shown in FIG. 8;

FIG. 10 is a perspective view showing a connection state of the planar transformer shown in FIG. 8;

[Explanation of symbols]

 B, flat transformer 31 base 31a top surface 31b front surface 31c side surface 33 base 34 resin insulating layer 35 storage section 36 auxiliary storage section 40 primary plane coil 37, 39A entrance section 38, 39B exit section 45, 52 conductive paste 46 secondary plane coil 43, 44 terminals 51, 53 terminals

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiro Makino 1-7 Yukiya Otsukacho, Ota-ku, Tokyo Alps Electric Co., Ltd.

Claims (7)

[Claims] A storage portion is formed in a base made of a magnetic material, and a primary planar coil and a secondary planar coil are stacked and stored in the storage portion in a mutually insulated state. At least one of the conductors is composed of a plurality of conductors, and an entrance and an exit reaching the primary planar coil and an entrance and an exit reaching the secondary planar coil are formed on the outer surface of the substrate, respectively. While a part of each planar coil is arranged at each of the inlet and outlet, a terminal made of a rigid body having a conductive paste disposed inside each of the inlet and outlet and an outer end out of the base is provided. A planar transformer, wherein each of the inserted terminals is electrically connected to a terminal portion of each of the planar coils in the base via a conductive paste. 2. The flat transformer according to claim 1, wherein the conductive paste is inserted into an entrance and an exit by screen printing. 3. The flat transformer according to claim 1, wherein the terminal of the primary planar coil and the terminal of the secondary planar coil are led out of the base in a direction intersecting with each other. 4. A substrate according to claim 1, wherein a resin insulating layer is formed at least inside the storage portion of the base.
3. The planar transformer according to any one of 3. 5. An outlet and an inlet of the primary planar coil are provided adjacent to each other on one surface of the base, and an outlet and an inlet of the secondary planar coil are provided with an outlet and an inlet of the primary planar coil. Are formed one by one on the other two surfaces adjacent to the surface provided with
The terminal of the primary planar coil and the terminal of the secondary planar coil are
2. The planar transformer according to claim 1, wherein the secondary planar coil is derived in an intersecting direction, and the secondary planar coil has a multi-layer coil structure in a housing portion of the base. 6. The planar transformer according to claim 1, wherein each of the planar coils has a laminated structure of a conductive sheet and an insulating sheet. 7. The substrate according to claim 1, wherein the base is divided into two parts in a thickness direction, a storage portion is formed in at least one base, and the divided base is covered with a resin insulating layer. 7. The planar transformer according to any one of 6.