JPH0638300U - Switching power supply circuit board - Google Patents

Abstract

(57) [Abstract] [Purpose] The main circuit part and the control circuit part can be electrically separated and shielded without changing the mounting volume or density of the switching power supply, and mutual interference due to radiated noise can be prevented. To provide a switching power supply circuit board capable of realizing stable operation of a switching power supply. A multi-layer board including a main switching circuit including a main switching element in a switching power supply for supplying a DC input and supplying an output to a secondary side of the transformer through a main switching element and a main transformer, and a control signal circuit thereof. Two
It is a switching power supply circuit board arranged at 0. The shield pattern of the circuit part that is susceptible to radiated noise is made to face the main switching circuit and the control signal circuit respectively with the shield pattern of the circuit part that is susceptible to radiated noise, and electrically isolated from each other. No eddy current circuit is formed in the pattern to prevent noise interference.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to the structure of a multi-layered board provided with measures against radiation noise when the main circuit and control circuit of a switching power supply are mounted on the same board.

[0002]

[Prior art]

 In order to miniaturize the switching power supply, the main circuit and the control circuit have been constructed with one board. In this case, it is necessary to take measures against radiation noise. For example, in a board-type switching power supply package or a DC-DC converter in which a communication load package is adjacently arranged in a tray, various measures have been taken to prevent mutual interference of radiation noise. As an example of this, place a circuit pattern on the board, attach another board to the pattern surface (non-component mounting surface) of the mounting board on which the component is mounted, and place the shield pattern on the entire back surface of the board. Multilayer substrates are often used.

[0003]

[Problems to be solved by the device]

 However, in this case, adjacent boards can prevent noise interference by the shield pattern.However, noise induced by the noise power generated by the switching operation of the main circuit in the same board can be prevented. The current still flows through the shield pattern on the main circuit side to the shield pattern on the control circuit side, which causes noise interference in the control circuit and makes the operation unstable.

The present invention has been made in view of the above circumstances, and a high-density mounting board intended for miniaturization has a main circuit which is a source of switching noise and a control circuit which is easily affected by noise. When the ICs are mounted on a single board at high density, a shield pattern should be provided to prevent radiated noise from the main circuit pattern surface of the switching power supply from interfering not only with the adjacent board but also with the self-board. By using the arranged multi-layer substrate, the main circuit part and the control circuit part can be electrically separated and shielded without changing the mounting volume and density of the switching power supply, and mutual interference due to radiated noise can be prevented. An object of the present invention is to provide a switching power supply circuit board that can realize stable operation of a switching power supply.

[0005]

[Means for Solving the Problems]

 For this purpose, the switching power supply circuit board of the present invention includes a main switching element in a switching power supply that supplies a DC input and supplies an output to a secondary side of the transformer through a main switching element. A switching power supply circuit board in which the main switching circuit and its control signal circuit are arranged on one multilayer board.The circuit pattern is arranged on one layer of the multilayer board to separate the main switching circuit component and the control signal circuit component. The multiple shield patterns are placed on the other layers of the multilayer board, and the multiple shield patterns face the positions of the main switching circuit components and the first shield pattern and the control signal circuit components. The second shield pattern to be electrically isolated and provided independently, and the shield corresponding to the main switching circuit Turn have as a feature that was one of the potential and the potential of the output voltage.

[0006]

[Action]

 It has been common practice to cover the noise source of the circuit with a metal shield plate. Even by providing a shield pattern on one surface of the multilayer substrate, the purpose of shielding radiation noise to the outside can be achieved. However, eddy currents due to radiation noise flow in the shield pattern, and this interferes with other circuit parts on the same substrate, such as control circuits. Therefore, the multilayer board of this invention electrically isolates the shield pattern of the circuit part that is susceptible to radiated noise from other shield pattern parts, and forms an eddy current circuit in the shield pattern of the circuit part that is susceptible to noise. It is a structure that prevents noise interference by preventing it from being touched.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings showing one embodiment. FIG. 1 is a sectional view of a multilayer board of this invention, FIG. 2 is a conceptual diagram of a package structure of a switching power supply which has an effect of preventing noise interference by this invention, and FIGS. 3 and 4 are conventional multilayer boards and this invention. It is a conceptual diagram which shows the distribution of the eddy current by the radiation noise which flows into the shield pattern of a multilayer substrate.

As shown in FIG. 1, the multilayer substrate 20 according to the present invention has a first circuit pattern 4 and a second circuit pattern 11 arranged on one surface or both surfaces of a glass epoxy layer 3, for example. Then, the first shield pattern 8 and the second shield pattern 9 are arranged on one surface of the other glass epoxy layer 7 to form the second layer 2. The first layer 1 and the second layer 2 form a laminated multilayer substrate so that the shield patterns 8 and 9 do not electrically overlap with the circuit patterns 4 and 11 of the first layer 1.

On one surface of the first layer 1, that is, the component mounting surface B, the main switching circuit component 5 and the control signal circuit component 6 are respectively arranged at corresponding positions of the first circuit pattern 1 and the second circuit pattern 11. Implement by separating into groups.

On the other hand, the shield pattern arranged on the back surface of the second layer has the first shield pattern 8 and the control signal circuit component 6 on the surface facing the portion where the main switching circuit component 5 is grouped and mounted. The second shield pattern on the surface facing the part where they are grouped and mounted is separately and independently patterned by the insulating band 10.

The multi-layer substrate 20 having the above-described structure is used by being incorporated in the package A of the switching power supply shown in FIG.

That is, the switching power supply package A is arranged with the component mounting surface B of the multilayer substrate 20 inside and the shield pattern surface outside.

On the other hand, the component mounting surface B side is covered with an aluminum shield plate E or the like to form a package.

With this configuration, the switching power supply circuit is covered with the shielding plate, and does not emit radiation noise to the outside.

In the shield pattern surface D, the second shield pattern 9 is island-shaped with respect to the first shield pattern 8 by the insulating band 10. The insulating band 10 is a portion where the shield material is not present and the glass epoxy layer is exposed.

Next, the operation of the thus configured switching power supply circuit board will be described with reference to the conceptual diagram showing the distribution of the eddy current due to the radiation noise flowing on the shield pattern surface in FIG. FIG. 3 shows a conventional shield pattern in which the control circuit part is entirely patterned in the main circuit part.

In this case, the radiation noise due to the switching generated in the main circuit portion flows as an eddy current as shown by an arrow in the figure on the shield pattern surface and also flows to the control circuit portion. This eddy current flowing in the control circuit section causes noise interference in the control circuit section, which causes unstable operation of the control circuit section.

In the circuit board of the present invention, as shown in FIG. 4, since the shield pattern of the control circuit section is insulated from the shield pattern of the main circuit section without islands, eddy current due to noise in the main circuit section Does not flow into the control circuit as indicated by the arrow in the figure. Therefore, the control circuit is not affected by noise.

The shield pattern (first shield pattern 8 in FIG. 1) of the main circuit section is clamped to either positive or negative potential of the output circuit of the switching power supply in order to keep the potential stable. If so, the noise interference effect can be made even more advantageous.

[0020]

[Effect of device]

 As described above, the multilayer board according to the present invention suppresses the radiation noise to the electronic circuit of the adjacent board by separating the shield pattern on the outer surface of the board from the control circuit section in the main circuit section, Unstable operation due to noise interference with other circuits such as the control circuit can also be prevented. Moreover, no additional structure is required to prevent noise, which is extremely advantageous as a package structure for a high-density mounting power supply.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a multilayer substrate according to the present invention.

FIG. 2 is a conceptual diagram of a package configuration of a switching power supply that exhibits a noise interference effect according to the present invention.

FIG. 3 is a conceptual diagram showing an eddy current distribution due to radiation noise flowing in a shield pattern of a conventional multilayer substrate.

FIG. 4 is a conceptual diagram showing an eddy current distribution due to radiation noise flowing in the shield pattern of the multilayer substrate of the present invention.

[Explanation of symbols]

 1 1st layer 2 2nd layer 3 Glass epoxy layer 4 1st circuit pattern 5 Main switching circuit component 6 Control signal circuit component 7 Glass epoxy 8 1st shield pattern 9 2nd shield pattern 10 Insulation band 11 Second circuit pattern 20 Multilayer substrate A Switching power supply package B Component mounting surface C Circuit pattern D Shield pattern surface E Aluminum shield plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Matsumoto 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Masatoshi Honda 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo No. Japan Nippon Telegraph and Telephone Corporation (72) Inventor Katsuro Maki 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (1)

[Scope of utility model registration request] 1. A main switching circuit including the main switching element in a switching power supply for supplying a DC input and supplying an output to a secondary side of the transformer through the main switching element and the main transformer, and a control signal circuit thereof. A switching power supply circuit board arranged on the multilayer board of
A circuit pattern is arranged on one layer of the multilayer board, main switching circuit parts and control signal circuit parts are separately mounted and arranged, and a plurality of shield patterns are arranged on another layer of the multilayer board. The shield pattern has a first shield pattern facing the position of the main switching circuit component and a second shield pattern facing the position of the control signal circuit component.
The shield pattern of is electrically separated and provided independently,
A switching power supply circuit board, wherein the shield pattern corresponding to the main switching circuit has the same potential as one potential of the output voltage.