JPH06325949A - Structure of electromagnetic circuit - Google Patents

Abstract

PURPOSE:To provide a structure of a small electromagnetic circuit while insulating a primary circuit from a secondary circuit. CONSTITUTION:An electromagnetic circuit comprises a coil layer 10 formed with multilayers of a plurality of planar coils with a spiral shape conductor pattern, a wiring layer 20 for an electronic circuit, placed on top of this coil layer, a shield layer 30 provided between this coil layer and the wiring layer, and a core 40 forming a magnetic circuit for this coil layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of an electromagnetic circuit used for a switching power supply or the like, and more particularly to miniaturization of insulating parts and improvement of high performance.

[0002]

2. Description of the Related Art FIG. 10 is a perspective view showing a conventional mounting structure of a switching power supply, in which (A) is a side view, (B) is a plan view, and (C) is a circuit diagram. A transformer T is mounted in the center of the printed circuit board, and a control circuit U1 for switching elements, switching elements Q1 and Q2, diodes D1 and D2, a capacitor C1 and the like are arranged around the transformer T. In such a device, a direct current is applied to the primary winding of the transformer T, and the switching element Q
It is turned on and off by 1 and Q2. Then, a switching signal is induced in the secondary winding of the transformer T, so that it is converted into a direct current by the rectifying and smoothing circuit composed of the diodes D1 and D2 and the capacitor C1 and supplied to the load. In this case, it is preferable to stabilize the output voltage by a negative feedback control circuit (not shown), which is performed by the control circuit U1.

[0003]

However, since the transformer for insulating the primary side circuit and the secondary side circuit from each other is large, there is a problem that the miniaturization of the entire power supply device is hindered. In addition, a bobbin is often used as a partition in the transformer in order to insulate the primary winding and the secondary winding from each other, but there is a problem that the transformer becomes larger due to this bobbin. The present invention has solved the above-mentioned problems, and an object thereof is to provide a small-sized electromagnetic circuit mounting structure while insulating the primary side circuit and the secondary side circuit.

[0004]

SUMMARY OF THE INVENTION The present invention which achieves the above object has a coil layer 10 in which a plurality of flat plate coils each having a spiral conductor pattern are laminated, and which is placed above the coil layer and is used for an electronic circuit. The wiring layer 20 to be mounted and the shield layer 30 provided between the coil layer and the wiring layer
And a core 40 constituting a magnetic circuit for this coil layer
It is characterized by having and.

[0005]

[Function] The coil layer is a portion corresponding to the winding of the transformer,
Uses a flat coil. Then, a wiring layer is provided on the coil layer via a shield layer, and an electronic circuit using this transformer is mounted. The shield layer prevents the influence of the switching signal flowing in the coil layer from affecting the wiring layer. The core causes electromagnetic induction with respect to the switching signal flowing in the coil layer.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Figure 1
Is a configuration perspective view showing an embodiment of the present invention, and FIG. 2 is a perspective view showing an assembled state. In the figure, the mounting parts are
There are capacitors C0 and C1, a switching transistor Q1, a switching control circuit U1 for stabilizing the output voltage, a rectifying diode D1, a resistor R, and a core 40 that is a magnetic component, and are mounted on the wiring layer 20. There is. The wiring layer 20 has the same function as that of a general printed board, and has a pattern for connecting the mounted components and the inner layer components.

The coil layer 10 is, for example, Japanese Patent Application No. 5-900.
The flat coil disclosed in the specification of No. 8 and the like is laminated, and a choke coil may be used instead of the transformer. With respect to the concentric spiral pattern formed on each flat coil of the coil layer 10, the core 40 is provided in the diameter direction to form a magnetic path, and the function as a transformer or a choke coil is improved. The shield layer 30 performs at least one of magnetic and electrostatic shields provided between the coil layer 10 and the wiring layer 20, and a switching signal which is turned on and off by the transistor Q1 flows through the coil layer 10. Since such a switching signal adversely affects the electronic circuit mounted on the wiring layer 20 as noise, it is provided to reduce the effect of noise. In this case, if a noise shielding material having a high thermal conductivity such as aluminum is used, it is convenient because it can also serve as a heat sink that releases the heat generated by the electronic circuit mounted on the wiring layer 20. The capacitor layer 40 is provided below the coil layer 10, and constitutes an electronic circuit together with a capacitor mounted on the wiring layer 20. For example, the capacitor layer 40 is formed by stacking a plurality of parallel flat plates, and an insulator or substrate between the layers acts as a dielectric.

With this structure, the coil of the transformer, the capacitor, and the heat sink are planarized, and these and the surface wiring layer are laminated to form a multifunctional printed circuit.
The core and other circuit components are mounted on the surface of the multifunctional printed circuit to reduce the size and thickness of the device. Further, since each circuit component can be connected to the planarized conductor and the insulating layer and the same plane or between the layers, there is an effect that it is excellent in compatibility with a general manufacturing process of a printed wiring board.

FIG. 3 is a circuit diagram of the switching power supply, and FIG. 4 is a configuration perspective view for explaining a mounted state of the circuit of FIG. The core of the transformer T is mounted in the central portion of the wiring layer 20, the switching Q1 such as FET and transistor is provided on the primary side of the transformer T, and the core members of the diodes D3 and D4 and the choke coil L1 are the transformer T. It is provided on the secondary side. A shield layer 30 is provided immediately below the wiring layer 20, and the coil internal wiring layer 1 is provided below the shield layer 30.
Two are provided. The coil internal wiring layer 12 is provided with a wiring pattern between the interlayer connection hole of the wiring layer 20 and the coil layer 10 or the capacitor layer 40, and when the wiring layer 20 is added together, a two-layer wiring region exists. Free wiring is possible. Preferably, since the coil internal wiring layer 12 is quieter magnetically and electrostatically than the coil layer 10, the coil internal wiring layer 12 has the ability to also serve as the shield layer 30.
If the coil internal wiring layer 12 is also used as the shield layer 30, the number of layers can be reduced, which contributes to cost reduction.

The coil layer 10 is provided below the coil internal wiring layer 12. Here, the primary winding n1 and the secondary winding n2 of the transformer T are provided in a laminated manner and mounted on the wiring layer 20. The core T is in a position where the magnetic influence is exerted. The winding n3 for the choke coil L1 is also provided in the coil layer 10, and is located at a position corresponding to the position where the core member of the choke coil L1 is arranged. Capacitor layer 40
Is provided below the coil internal wiring layer 12,
Here, the output capacitor C2 is provided. Here, since the occupying regions of the windings n1 to n3 are a part of the coil internal wiring layer 12, they are arranged in a distributed manner without taking the laminated structure as in the example of FIG.

FIG. 5 is a block diagram showing an application example of the present invention to a DC-DC converter, (A) is a front view, (B) is a plan view, and (C) is a side view. The circuit diagram of the DC-DC converter is the same as that of FIG. 10C, and since only the wiring layer 20 can secure a region in which the control circuit U1 and the capacitor C1 can be mounted, the lower wiring layer 22 is provided below the coil layer 20. And other parts are mounted. A primary winding n1 and a secondary winding n2 of the transformer T are laminated and provided on the coil layer 10, and a core 40 is mounted so as to surround the coil layer 10, the wiring layer 20, and the lower wiring layer 22. An input terminal 51 and an output terminal 52 are provided. Therefore, the power supply circuit is becoming smaller and thinner.

6A and 6B are explanatory views of the circuit arrangement in the wiring layer 20, where FIG. 6A shows a correct circuit arrangement, and FIG. 6B shows an arrangement which causes trouble in the circuit operation. The wiring layer 20 has a circuit 1,
2 is provided, but since the coil layer 10 is provided as the lower layer, it is necessary to dispose the coil layer 10 so that mutual interference does not occur between the transformer and other electronic circuits. Since the circuits 1 to 3 are in positions where the main magnetic flux of the transformer and the circuit do not interlink,
There is little interference from the circuit to the transformer operation. However, since the circuit 4 is located at a position where the main magnetic flux of the transformer crosses the circuit, a current flows through the circuit to hinder the operation of the transformer. Therefore, the circuit is arranged in the wiring layer 20 at a position where the main magnetic flux of the transformer does not cross the circuit.

FIG. 7 is a block diagram for reducing the leakage magnetic flux of the transformer. FIG. 7A shows the circuit arrangement and FIG. 7B shows the flow of the magnetic flux. A circuit 5 that surrounds the core 40 with a closed curve is provided in the wiring layer 20. The leakage magnetic flux induces a current in the closed circuit 5, but the magnetic flux generated by this induced current is in the direction of canceling the original leakage magnetic flux, so that the leakage magnetic flux is suppressed and magnetic interference with the surface circuit due to the leakage magnetic flux is reduced. can do.

FIG. 8 is an explanatory view of the shield layer 30. (A)
Shows a perspective view of the whole structure, (B) shows a case of primary and secondary division, and (C) shows a case of further meshing. The conductive shield layer 30 substantially forms a closed circuit with respect to the transformer, and therefore has an effect of reducing interference due to leakage magnetic flux. Also, there is electrostatic interference from the coil pattern of the coil layer 10 to the circuit of the wiring layer 20, but this is also achieved by providing the shield layer 30 between the wiring layer 20 and the coil layer 10. To be done.

Next, when the shield layer 30 is divided into the primary and the secondary, there is an effect that the shielding effect can be obtained without increasing the electrostatic coupling between the primary and the secondary of the transformer. In this case, each shield layer is connected to a low potential point (ground) in circuit operation. Further, when the conductor pattern is made into a mesh, the stray capacitance between the high potential coil and the shield layer can be reduced and the characteristics can be made factory without impairing the shielding effect. Here, since the shield layer has a certain degree of conductivity, it can be formed by printing a conductive paste or the like, and can be inserted at low cost when manufacturing a multilayer circuit.

FIG. 9 is a perspective view of the entire structure including the core 40. Here, an EE type core is used as the core 40, and the middle leg core penetrates through the center of the spiral conductor pattern of the coil layer 10. However, since the magnetic circuit may obtain the required characteristics as a transformer without necessarily forming a closed magnetic circuit, in such a case, the plate-shaped core is used as the coil layer 1.
It may be attached to the front surface and the back surface of 0, and even when there is a metatarsal core, it is not necessary to penetrate the center of the spiral conductor pattern of the coil layer 10.

[0017]

As described above, according to the present invention,
Since various components are mounted on the wiring layer and the coil of the transformer is planarized and these and the wiring layer are laminated to form a multifunctional printed circuit, there is an effect that the device can be made smaller and thinner. Further, since each circuit component can be connected to the planarized conductor and the insulating layer and the same plane or between the layers, there is an effect that it is excellent in consistency with a general printed wiring board manufacturing process.

[Brief description of drawings]

FIG. 1 is a configuration perspective view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an assembled state of the apparatus shown in FIG.

FIG. 3 is a circuit diagram of a switching power supply.

FIG. 4 is a configuration perspective view illustrating a mounted state of the circuit of FIG.

FIG. 5 is a configuration diagram showing an application example of the present invention to a DC-DC converter.

FIG. 6 is an explanatory diagram of a circuit arrangement in the wiring layer 20.

FIG. 7 is a configuration diagram in the case of reducing leakage magnetic flux of a transformer.

FIG. 8 is an explanatory diagram of a shield layer 30.

9 is a perspective view of the entire configuration including a core 40. FIG.

FIG. 10 is a configuration perspective view showing a mounting structure of a conventional switching power supply.

[Explanation of symbols]

 10 coil layer 20 wiring layer 30 shield layer 40 core

Claims (2)

[Claims] 1. A coil layer (10) in which a plurality of flat plate coils each having a spiral conductor pattern are laminated, and a wiring layer (2) placed above the coil layer and having an electronic circuit mounted thereon.
0), a shield layer (30) provided between the coil layer and the wiring layer, and a core (40) constituting a magnetic circuit for the coil layer, an electromagnetic circuit mounting structure. 2. A coil layer (10) in which a plurality of flat-plate coils having a spiral conductor pattern are laminated, and a wiring layer (2) which is placed above the coil layer and on which an electronic circuit is mounted.
0), a shield layer (30) provided between the coil layer and the wiring layer, and a core (40) forming a magnetic circuit for the coil layer, and the vortex center of the conductor pattern of the coil layer. Is provided with a core insertion hole, the shield layer and the wiring layer are provided with a core insertion hole corresponding to the core insertion hole, and a part of the magnetic path of the core is attached to the core insertion hole. Mounting structure of electromagnetic circuit.