JP3095350B2 - Sheet coil laminated type transformer and its terminal structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention proposes a transformer suitable for radiating heat generated in a sheet coil of a transformer using a laminated body of sheet coils for winding. More specifically, the present invention relates to a configuration in which a heat radiation effect of a terminal electrically connected to a sheet coil is improved.

[0002]

2. Description of the Related Art In order to reduce the thickness and size of inductance components such as transformers and choke coils, a sheet coil having an arc-shaped or spiral-shaped conductor pattern formed on an insulating substrate (sheet or the like) is used as its winding. This is one of the effective means. FIGS. 8 (perspective view) and FIG. 9 show an example of a transformer using a sheet coil.
(Side view). Generally, when a sheet coil is used as a transformer winding, the primary winding and the secondary winding (for each output winding when the secondary winding also has a plurality of outputs) are formed of separate sheet coils. Is done. Therefore, the windings of the transformers shown in FIGS. 8 and 9 are constituted by a sheet coil laminate 2 in which a plurality of sheet coils are laminated.

In the sheet coil laminate 2, through holes 3A to 3D and through holes 5A to 5D are formed by through holes provided in each sheet coil. Each through-hole is in a state of being electrically connected or insulated with a conductor pattern of a predetermined sheet coil. In these through holes 3A, 3D and through holes 5A to 5D,
The terminals 4A and 4D and the terminals 6A to 6D are inserted and soldered. The core 1 is fitted to the sheet coil laminate 2 so as to cover the conductor pattern provided on the sheet coil, thereby forming a sheet coil laminate type transformer.

FIGS. 8 and 9 schematically show the laminated state of each sheet coil and the connection state of each terminal (4A, 4D, 6A to 6D) constituting the sheet coil laminated body 2 of the sheet coil laminated type transformer shown in FIGS. FIG. 10 to FIG. First, in FIG. 10, the primary sheet coil 2a-
Each of the sheet coils is stacked such that 1, 2a-2 are on the upper side (opposite side of the mother board MB), and the secondary sheet coils 2b-1 and 2b-2 serving as secondary windings are on the lower side (mother board MB side). The conductor patterns of the primary side sheet coils 2a-1 and 2a-2 are connected to the terminals 4A and 4D and the secondary side sheet coils 2b-1 and 2b-
The two conductor patterns are electrically connected to the terminals 6A to 6D, respectively. (Here, the mother board MB
It is assumed that various electronic components are mounted in addition to the sheet coil type laminated transformer, and the electronic components are electrically connected to each other by a conductor pattern on the surface to form a functional circuit. This configuration is used when the heat dissipation of the transformer is important.

That is, in a transformer incorporated in a power supply circuit, a larger amount of current may flow through the secondary winding than the primary winding due to the relationship of the number of turns. More. When the winding is formed of a sheet coil laminate, the heat generated in the conductor pattern of the sheet coil is transmitted through the insulator substrate of the laminated sheet coil and is radiated from the surface of the sheet coil laminate, or The terminal connected to the terminal is conducted, and the heat is radiated from the surface of the terminal and the conductor pattern on the motherboard connected to the terminal. Therefore, in FIG. 10, the secondary side sheet coil 2b
-1, 2b-2 are arranged near the surface of the motherboard in the sheet coil laminate 2, and a heat conduction distance (hereinafter referred to as a heat conduction distance) between a heat-generating portion (that is, the sheet coil) and a heat-radiating portion (mother substrate MB). ) Is shortened to improve the heat radiation effect.

[0006] However, the laminated structure of the sheet coil shown in FIG. 10 has a high heat dissipation effect, but has a disadvantage that the coupling between the windings is low. If the coupling between the windings is reduced, the conversion efficiency as a transformer is deteriorated (decreased), which leads to an increase in heat generation. By the way, the size of the transformer
It is greatly affected by the heat generated in the transformer and its heat dissipation. When the temperature of the transformer rises, the shape of the transformer must be increased and its surface area must be increased for heat dissipation. Therefore, in view of the relationship between the heat radiation effect and the amount of heat generated, it was not possible to greatly reduce the size of the transformer even in the configuration of FIG.

On the other hand, in FIG. 11, the primary sheet coils 2a-1 and 2a-2 serving as primary windings are divided, and the primary sheet coils 2a-1 and 2a-2 are divided by the secondary sheet coils 2a-1 and 2a-2.
b-1 and 2b-2 are sandwiched between the sheet coils, and the conductor patterns of the primary sheet coils 2a-1 and 2a-2 are connected to the terminals 4A and 4D and the secondary sheet coils 2b-1 and 2b-2. The conductor pattern 2b-2 is electrically connected to the terminals 6A to 6D, respectively. This configuration is used when importance is placed on the coupling between the windings of the transformer. That is,
It is known that a sandwich structure of windings in which primary windings and secondary windings are alternately stacked reduces an average distance between the windings and reduces leakage of interlinking magnetic flux. In FIG. 11, the secondary sheet coils 2b-1 and 2b-2 are sandwiched between the primary sheet coils 2a-1 and 2a-2 to improve the coupling between the windings.

However, in the laminated structure of the sheet coil in which the windings have a sandwich structure, the coupling between the windings is high but the heat radiation effect tends to be low. In particular, when the secondary sheet coils 2b-1 and 2b-2 are arranged at the center of the sheet coil laminate as shown in FIG. 11, heat is confined in the sheet coil laminate. However, contrary to FIG. 11, the secondary sheet coils 2b-1 and 2b-2 are divided as shown in FIG. 12, and the secondary sheet coils 2b-1 and 2b-2 are divided by the primary sheet coil 2a-2. One, two
When lamination is carried out so as to sandwich a-2, the efficiency of the transformer may be reduced.

That is, due to the turn ratio of the primary winding and the secondary winding, the length of the coil conductor of the conductor pattern of the primary sheet coil is longer than that of the secondary sheet coil. Therefore, the amount of increase (absolute amount) of the electric resistance with respect to the temperature rise is larger in the primary winding. If the secondary sheet coils 2b-1 and 2b-2 arranged on both outer sides in the stacking direction of the sheet coil laminate 2 do not sufficiently radiate heat, the primary coil arranged at the center of the sheet coil laminate 2 There is a possibility that the temperature of the side sheet coils 2a-1 and 2a-2 increases, and the efficiency of the transformer decreases with an increase in electric resistance. Therefore, the downsizing and high efficiency of the transformer can be achieved by the secondary sheet coil 2b-1, which generates a large amount of heat,
The point is whether to release the heat of 2b-2.

[0010]

As described above, the heat generated in the sheet coil is transmitted through the insulating substrate of the sheet coil to the surface of the sheet coil laminate, and is connected to the conductor pattern of the sheet coil. The heat is dissipated along the path leading to the terminal surface and the conductor pattern on the mother board through the terminal. Considering the path for conducting the terminal among the two heat radiation paths, the conventional connection structure between the sheet coil and the terminal shown in FIG. 12 may have insufficient heat radiation of the sheet coil on the side away from the motherboard. .

For example, when the secondary winding is a parallel split winding, the secondary side sheet coils 2b-1 and 2b-2 are shared by terminals (6A, 6D). Here, when the heat generated in the secondary side sheet coils 2b-1 and 2b-2 is conducted to the terminals 6A and 6D and the temperature of the terminals 6A and 6D is increased, the direction of heat conduction is from the sheet coil to the mother board MB. The temperature of the terminals 6A and 6D increases as the distance from the mother substrate increases. Regarding the secondary sheet coil 2b-2 on the mother board MB side, since the thermal gradient (temperature gradient) between the sheet coil and the terminal is large, the heat generated in 2b-2 is smoothly transmitted to the terminals 6A and 6D. . But mother board MB
With respect to the secondary side sheet coil 2b-1 away from the terminal, the temperature generated by the heat generated in 2b-2 is transmitted to the terminals 6A and 6D, and the thermal gradient between the sheet coil and the terminal decreases. , 2b-1 is hardly conducted to the terminals 6A, 6D.

The secondary winding is not divided into parallel windings.
When the secondary sheet coils 2b-1 and 2b-2 are used as independent output channels, the secondary sheet coil 2b
-1 is connected to the terminals (6B, 6C) in the through holes (provisionally 5B, 5C), and is connected to the secondary side sheet coil 2b-.
2 is a terminal (6A, 6D) in the through hole (5A, 5D)
Connected. Here, the secondary side sheet coil 2b-1 remote from the mother board MB is connected to its terminals 6B and 6B.
The heat transfer distance to the mother substrate MB of C becomes long. In addition, portions of the terminals 6B and 6C that are accommodated in the through holes 5B and 5C cannot dissipate heat from their surfaces. For the above reasons, heat easily stays in the portions of the terminals 6B and 6C that are accommodated in the through holes, and the thermal gradient between the sheet coil and the terminals is reduced. Therefore 2
The heat radiation effect via the terminals 6B and 6C of the secondary sheet coil 2b-1 is caused by the secondary sheet coil 2b-2 on the mother board MB side.
Radiating action through the terminals 6A and 6D of
The temperature of the secondary sheet coil 2b-1 may increase.

In the drawings and the description, for convenience, the primary and secondary are composed of two sheet coils, but the number of sheet coils constituting each winding is actually larger. Naturally, if the number of stacked sheet coils increases, the above-mentioned disadvantageous phenomenon becomes more serious. Therefore, the present invention
It is an object of the present invention to provide a terminal structure capable of sufficiently dissipating heat generated in a sheet coil in a sheet coil laminated type transformer, thereby reducing the size and efficiency of the transformer.

[0014]

SUMMARY OF THE INVENTION The present invention relates to a sheet coil laminated type transformer in which sheet coils for obtaining inductance by a conductor pattern provided on an insulating substrate are laminated and the laminated sheet coil is used as a winding. The sheet coil which becomes the winding having a large heat value is divided and arranged on both outer sides in the stacking direction in the sheet coil laminate, and the terminals connected to the divided sheet coil having the large heat value are arranged on the respective sides. Characterized in that the sheet coil laminate is separately drawn from the surface in the laminating direction of the sheet coil laminated body.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Each of the sheet coils is laminated so that a primary side sheet coil having a small amount of heat is divided into two parts and a secondary sheet coil having a large amount of heat is arranged on both outer sides in a laminating direction. A sheet coil laminate is formed. A first terminal including a first connection portion housed in the through hole of the sheet coil laminate, a first vertical lead extending from the surface of the sheet coil laminate on the motherboard side to the surface of the motherboard; and a sheet. A second connection portion accommodated in the through hole of the coil laminate, a parallel lead portion extending from the through hole to an end of the sheet coil laminate on a surface of the sheet coil laminate opposite to the mother board; A second terminal having a second vertical lead extending from an end of the body to a surface of the motherboard is formed.

A first terminal is inserted from the mother board side into a through hole to which a conductor pattern of the sheet coil disposed on the mother board side of the sheet coil laminate is electrically connected, and a mother board of the sheet coil laminate is provided. A second terminal is inserted from a side opposite to the mother board into a through hole to which a conductor pattern of a sheet coil arranged on the side opposite to the board is electrically connected. Each terminal is soldered to the conductor pattern in the through hole, and the terminals are fixed at the same time as the electrical connection.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 (perspective view) and FIG. 2 (side view) show the external shape of a sheet coil laminated transformer according to the present invention to which a terminal structure capable of sufficiently dissipating heat of a sheet coil is applied.
It was shown to. 1 and 2, the same components as those shown in FIGS. 8 and 9 are denoted by the same reference numerals, and the illustration of the motherboard is omitted. 1 and 2, the sheet coil laminate 2 has a configuration in which a sheet coil serving as a primary winding is located at the center and a sheet coil serving as a secondary winding is divided into two parts and arranged on both outer sides in the stacking direction. I have.

The through-holes 3A to 3D of the sheet coil laminate 2
And the through holes 5A to 5D are formed by through holes provided in the respective sheet coils, and the through holes 3A and 3D are electrically connected to the conductor pattern of the sheet coil for the primary winding. is there. In addition, through holes 5A, 5A
D is the conductor pattern of the sheet coil arranged on the mother board side (downward) of the divided secondary coil sheet coils, and the through holes 5B and 5C are the divided secondary coil sheet coils. Among them, each of them is in a state of being electrically connected to the conductor pattern of the sheet coil arranged on the opposite side (upper side) of the mother board.

Here, the first terminals 7A, 7D are inserted into the through holes 5A, 5D from the mother board side, respectively. The first terminals 7A and 7D are connected to a connection portion A- inserted into the through hole.
1 and D-1 and vertical lead portions A-2 and D-2 extending from the surface of the sheet coil laminate 2 on the mother substrate side to the surface of the mother substrate. Has the same structure as the conventional terminals 6A to 6D shown in FIG. Then, the second terminals 7B and 7C are inserted into the through holes 5B and 5C from the side opposite to the mother board, respectively. This second terminal 7
B, 7C are connection parts B-1, C- stored in the through holes.
1, a parallel lead portion B-2 extending from the through hole to the end of the laminate on the surface of the sheet coil laminate 2 opposite to the mother board;
C-2 and second vertical lead portions B-3 and C-3 extending from the end of the stacked body to the surface of the mother substrate. The structure of the core 1 and the terminals 4A and 4D on the primary side are the same as those of the related art, and the description is omitted.

In the sheet coil laminated type transformer shown in FIGS. 1 and 2, the laminated state of each sheet coil constituting the sheet coil laminated body 2 and the connection state of the terminals 4A, 4D, 7A to 7D are modeled. FIG. 3 shows this. As can be seen from FIG. 3, the primary side sheet coil 2a-
1 and 2a-2 are arranged at the center, and the secondary sheet coils 2b-1 and 2b-2 serving as secondary windings are respectively located on the opposite side (upper) to the mother board MB and on the mother board MB side (lower). By dividing and arranging, the primary winding is sandwiched between the secondary windings (sandwich structure). Primary side sheet coil 2a
-1 and 2a-2 are connected to the terminals 4A and 4D as in the prior art. On the other hand, the secondary sheet coil 2b-2 arranged on the mother board MB side includes the first terminals 7A and 7D inserted from the mother board MB side and the secondary side coil arranged on the opposite side to the mother board MB. The sheet coil 2b-1 is individually connected to the second terminals 7B and 7C inserted from the side opposite to the mother board MB.

The heat generated in the secondary sheet coil 2b-2 is conducted to the terminals 7A and 7D, and the connection portions (A-1, D-1) of the terminals 7A and 7D and the vertical lead portions (A-2, D). −
2), heat is conducted along the path of the conductor pattern on the mother board MB,
Surfaces (vertical leads) of terminals 7A and 7D and mother board MB
Heat is dissipated from the upper conductor pattern. Regarding the secondary sheet coil 2b-2, the secondary sheet coil 2b-2
The heat conduction distance from the substrate to the conductor pattern on the mother board MB is short, and a sufficient heat radiation effect can be obtained. On the other hand, the heat generated in the secondary sheet coil 2b-1 is conducted to the terminals 7B and 7C,
Connection portions (B-1, C-1) of terminals 7B and 7C, parallel lead portions (B-2, C-2), vertical lead portions (B-3, C-
3), heat is conducted along the path of the conductor pattern on the mother board MB,
Surfaces of terminals 7B and 7C (parallel lead, vertical lead)
Further, heat is radiated from the conductor pattern on the mother board MB.

As for the terminals 7B and 7C, the parallel lead portions (B-2 and C-2) can be seen only from the heat conduction distance between the heat-generating portion (sheet coil) and the heat-radiating portion (conductor pattern on the mother board MB). ), Which seems to be more disadvantageous to the heat dissipation effect than before. However, the parallel leads (B
-2, C-2) and the vertical lead portions (B-3, C-3) are both exposed, and conduct the heat generated in the sheet coil to the mother board MB and also radiate heat from the surface. Moreover, in the direction of heat conduction from the connection portions (B-1, C-1) to the parallel lead portions (B-2, C-2), heat stays at the connection portions (B-1, C-1). Nothing. Therefore, the thermal gradient between the sheet coil and the terminal (connection portion) becomes large, and the heat generated in the secondary sheet coil 2b-1 is successively transmitted to the terminals 7B and 7C and radiated, so that the heat radiation effect is high. Become.

When the secondary windings, that is, the secondary side sheet coils 2b-1 and 2b-2 are used by being divided into parallel windings, the connecting portions (A-1 and D-1) of the terminals 7A and 7D are connected. ,
2b-1 together with the secondary sheet coil 2b-2, and 2b-2 together with the secondary sheet coil 2b-1 at the connection portions (B-1, C-1) of the terminals 7B and 7C. May be connected. Secondary side sheet coil 2b-1,
There is no difference in the heat radiation action of the terminals 7A, 7D and the terminals 7B, 7C, regardless of whether 2b-2 is a parallel split winding or a separate output channel.

Next, an example of a specific method of forming these terminals 7A to 7D during the production of a transformer will be briefly described. The terminals 7A, 7D and the terminals 7B, 7C are inserted in opposite directions in the sheet coil laminate 2 into the through holes 5A to 5D, respectively. Accordingly, the first piece 10 shown in FIG.
And the second piece 11. The first piece 10 has terminals 7A and 7D of the same shape and the same insertion direction with respect to the frame portion 8.
Are formed on the second piece 11, and terminals 7B and 7C having the same shape and the same insertion direction with respect to the frame portion 9 are formed. It is technically the easiest and most reliable method to manufacture a piece for each terminal having the same shape and the same insertion direction. However, the terminals of the transformer illustrated in the figure have four terminals on one side. However, for a transformer requiring more terminals (for example, a multi-output type, eight terminals, etc.), depending on the terminal shape and insertion direction. Cannot be made with just two pieces.

On the other hand, in FIG. 5, the terminals 7A to 7D are
The case where only the piece 13 is formed is shown. The third piece 13 has terminals 7A, 7B,
7C and 7D are formed, and the shape before mounting on the transformer and the procedure for mounting on the transformer are as shown in FIG. At the time of forming the third piece 13, the terminals 7 A to 7 D are not formed in the final shape, the bending angle of each terminal is reduced, and the joint between the terminal and the frame 12 is bent to form the terminal 7.
Connections of A and 7D (A-1, D-1) and terminals 7B and 7C
(B-1, C-1) are open. When attaching the third piece 13 to the transformer,
Each of the opened connection portions is fitted to the sheet coil laminate 2, and after positioning, each terminal portion is caulked. Each terminal has a final shape by this caulking.

In order to form each terminal in one piece in this way, a certain processing technique is required, and the number of processing steps per piece is also increased. However, there is an advantage that the number of pieces does not need to be increased even when the number of terminals of the transformer is large as described above, and the number of manufacturing steps does not largely change. If a higher heat radiation action is required for the terminals, the input / output terminals of the sheet coil may be formed of a plurality of terminals instead of a pair of terminals. In this case, the terminal may be formed, for example, as shown in FIG. In the fourth piece 15 shown in FIG. 7, 7E is formed in addition to the terminals 7C and 7D, and 7D and 7E are electrically connected to the same sheet coil. The number and shape of the terminals may be freely selected as needed.

[0027]

As described above, according to the present invention, in a transformer using a sheet coil laminate as a winding, a terminal connected to a sheet coil having a large calorific value among the sheet coils is a terminal of the sheet coil. According to the arrangement in the laminate, the sheet coil laminate is drawn out from both sides in the laminating direction. With this structure, a sufficient thermal gradient (temperature gradient) necessary for heat conduction (heat transfer) can be obtained between each terminal and each sheet coil. Then, the heat generated in the sheet coil is conducted to the terminal, and is radiated from the exposed terminal surface and the conductor pattern on the motherboard. As a result, according to the present invention, the heat radiation of the sheet coil serving as the secondary winding is effectively performed, and the size and efficiency of the sheet coil laminated transformer can be reduced.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a sheet coil laminated type transformer according to the present invention.

FIG. 2 is an external side view of the sheet coil laminated transformer according to the present invention.

FIG. 3 is a model diagram of a sheet coil laminated structure and a terminal connection structure of the sheet coil laminated type transformer according to the present invention.

FIG. 4 is a first example of a method for forming a terminal.

FIG. 5 shows a second example of a method for forming a terminal.

FIG. 6 is a mounting procedure of the terminal shown in FIG. 5;

FIG. 7 shows a third example of a method for forming a terminal.

FIG. 8 is an external perspective view of a conventional sheet coil laminated type transformer.

FIG. 9 is an external side view of a conventional sheet coil laminated transformer.

FIG. 10 is a model diagram of a first example of a sheet coil laminated structure and a terminal connection structure of a conventional sheet coil laminated type transformer.

FIG. 11 is a model diagram of a second example of a sheet coil laminated structure and a terminal connection structure of a conventional sheet coil laminated type transformer.

FIG. 12 is a model diagram of a third example of a sheet coil laminated structure and a terminal connection structure of a conventional sheet coil laminated type transformer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core 2 Sheet coil laminated body 3 (AD) Through hole 4 (A, D) Terminal (primary side) 5 (AD) Through hole 6 (AD) Terminal (secondary side: conventional) 7 (A, D) 1st terminal (secondary side: this invention) 7 (B, C) 2nd terminal (secondary side: this invention) A-1, D-1 Connection part of 1st terminal A -2, D-2 Vertical lead portion of first terminal B-1, C-1 Connection portion of second terminal B-2, C-2 Parallel lead portion of second terminal B-3, C-3 Vertical lead part of second terminal MB mother board

Claims (4)

(57) [Claims] 1. A sheet coil laminated type transformer in which a sheet coil for obtaining an inductance by a conductor pattern provided on an insulating substrate is laminated and a laminated body of the sheet coil is used as a winding. Are arranged on both outer sides in the laminating direction in the sheet coil laminate, and the terminals connected to the divided sheet coils having a large heat value are connected to the respective sheet coil laminates on the respective arranged sides. A sheet coil laminated type transformer which is separately drawn from a surface of a body in a laminating direction. 2. The method according to claim 1, wherein the coil having a large calorific value is divided into parallel windings by connecting in parallel the sheet coils divided on both outer sides in the stacking direction in the sheet coil stack. The sheet coil laminated type transformer according to claim 1. 3. A sheet coil laminated type transformer in which a sheet coil for obtaining an inductance by a conductor pattern provided on an insulating substrate is laminated and the laminated body of the sheet coil is used as a winding, a winding having a large heat value is It is formed by a plurality of sheet coils connected in parallel as a parallel split winding, and in this case, the plurality of sheet coils serving as the windings generating a large amount of heat are divided into two on both outer sides in the stacking direction in the sheet coil stack. A terminal connected to the sheet coil generating a large amount of heat has at least one of an input side and an output side drawn out from both sides in the stacking direction of the sheet coil stacked body. 4. A first connecting portion which is inserted from a motherboard side into a through hole for connecting a terminal of the sheet coil laminate and is electrically connected to a conductor pattern of the sheet coil, and a motherboard of the sheet coil laminate. Terminal provided with a first vertical lead portion extending from the side surface to the surface of the mother board, and a conductor of the sheet coil inserted into a through hole for connecting a terminal of the sheet coil laminate from a side opposite to the mother board. A second connection portion electrically connected to the pattern, a parallel lead portion extending from the through hole to an end of the sheet coil laminate on a surface of the sheet coil laminate opposite to the mother board; A terminal structure of a sheet coil laminate in which a second terminal provided with a second vertical lead extending from an end to a surface of the mother board is combined.