JP3121544U - Circuit board device for preventing electromagnetic interference - Google Patents

Abstract

An electromagnetic interference suppression circuit board device capable of efficiently preventing electromagnetic interference in a circuit and reducing the area of an electronic product is provided.
At least two circuit boards 21 and 22 that overlap each other have electronic circuits, the first circuit board 21 has a high-speed unit 230, and the high-speed unit 230 has high-frequency electromagnetic noise in the surrounding environment. May generate electromagnetic interference to the electronic circuit. The at least one shielding frame 20 is made of a metal material, is sandwiched between the circuit board 21 and the circuit board 22, and is electrically connected to the ground potential of the circuit board 21 and the circuit board 22. The high-speed unit 230 is disposed in the shielding frame 20. The shielding frame 20 can connect the circuit board 21 and the circuit board 22 adjacent to each other and completely cover the high-speed unit 230 to induce electromagnetic interference to the ground potential. It is.
[Selection] Figure 3

Description

  The present invention relates to a circuit board device, and more particularly to a circuit board device capable of preventing high-frequency electromagnetic noise from interfering with the characteristics of an electronic circuit.

  When placing an electronic unit on a general circuit board, it is necessary not only to place it based on the characteristics and functions of the electronic circuit, but also to prevent reactions or electromagnetic interference due to the electrical connection between the units. Is an important consideration. For example, when it is necessary to operate an electronic circuit in a high-speed digital processing device, a rapidly switchable control switch unit, or an antenna that transmits a high-frequency signal in a high-frequency circuit, these electronic units are used in a high-speed or high-frequency operating environment. Since high-frequency electromagnetic waves are constantly emitted, analog transmission signals such as analog visual signals and audio signals are interfered with by some electromagnetic noise and affected by the signal transmission function. Therefore, when designing the arrangement of the circuit board, it is necessary to consider adding an electromagnetic wave interference preventing function.

  FIG. 1 and FIG. 2 show a known circuit board 1 with an electromagnetic interference prevention function. As shown in FIG. 1, the electronic circuit arrangement of the circuit board 1 includes a plurality of high-frequency circuit parts 11, and the high-frequency circuit part 11 is configured by concentrating and distributing a plurality of electronic units 110 that emit high-frequency electromagnetic wave noise. The effective circuit adjacent to 110 and the outer periphery thereof are surrounded by a metal frame 111 that is electrically grounded. Therefore, as shown in FIG. 2, high frequency noise can be induced to the ground potential by covering the high frequency circuit portion 11 with the metal cover 12 and bringing the metal cover 12 and the metal frame 111 into mutual contact. These high-frequency circuit parts 11 do not cause high-frequency electromagnetic noise to be emitted and affect the electrical characteristics of other electronic circuits in the circuit 1, and by isolating them through these metal frames 111, The respective high frequency electronic units 110 located in the high frequency circuit part 11 are not subjected to mutual interference of high frequency electromagnetic waves. However, these metal covers 12 must be provided one by one in accordance with the circuit arrangement form of the high-frequency circuit portion 11, so that it takes much time and effort to manufacture. Further, when the design is made so that the high-frequency circuit parts 11 are concentrated, it is only necessary to manufacture a single metal cover 12. However, if the high-frequency circuit parts 11 do not mesh so that the boundaries of these high-frequency circuit parts 11 cross, The space between 11 is wasted and the circuit board 1 occupies a relatively large space. If this is solved by a hardware design that increases the number of circuit boards, the area of the electronic product is increased, and as a result, another circuit function must be reduced. Therefore, the function of the entire electronic product is degraded.

  The main object of the present invention is to reduce the area of the electronic product by efficiently preventing electromagnetic interference in the circuit and simplifying the circuit design space by simplifying and low-cost structure. It is an object to provide a circuit board device for suppressing electromagnetic interference.

  In order to achieve the above-described object, a circuit board device according to the present invention includes at least two circuit boards that overlap each other and a shielding frame that is disposed between two adjacent circuit boards. The circuit board has an electronic circuit, of which the first circuit board has at least one high-speed unit, the high-speed unit emits high-frequency electromagnetic noise to the surrounding environment, and electromagnetic interference (EMI) with respect to the electronic circuit described above. ) May be generated. The shielding frame is made of a conductive metal material and is electrically connected to the ground potential (Ground) of the two circuit boards. The high-speed unit is disposed in the shielding frame. The shielding frame connects and fixes two adjacent circuit boards, and completely covers the high-speed unit, thereby inducing the above-described electromagnetic interference to the ground potential.

The configuration and effects of the present invention will be described below based on the drawings and examples. First, the description of the drawings is as follows.
FIG. 3 is an exploded perspective view of the first embodiment of the present invention.
FIG. 4 is an exploded perspective view of the second embodiment of the present invention.

FIG. 5 is an exploded perspective view of the third embodiment of the present invention.
FIG. 6 is a perspective view showing a circuit located on the lower surface of the analog circuit board provided in the third embodiment.
FIG. 7 is a partial perspective view after the combination of the third embodiment described above.

  As shown in FIGS. 1 to 3, in the electromagnetic interference prevention circuit board device 2 according to the first embodiment of the present invention, the shielding metal frame 20 is sandwiched between the lower layer main circuit board 21 and the upper layer main analog circuit board 22. The lower-layer main circuit board 21 is mainly arranged so that electronic circuits for high-speed operation processing are distributed, and the upper-layer analog circuit board 21 is mainly arranged so that analog circuits capable of transmitting analog signals are distributed. Since the two circuit boards 21 and 22 further have a general digital logic circuit that transmits only a digital signal, it is not necessary to consider that the electromagnetic wave interferes with another signal transmission. Hereinafter, the structural relationship between the two circuit boards 21, the circuit board 22, and the shielding frame 20 will be described in detail.

  The main circuit board 21 includes a high frequency circuit part 23 and a digital circuit part 24 and is divided into an upper surface 210 and a lower surface 211 facing each other. The high-frequency circuit part 23 has a plurality of high-speed units 230 and a ground circuit 231 disposed on the upper surface 210. The ground circuit 231 is distributed around the effective circuit portion of the high-speed unit 230. The high-speed unit 230 includes an arithmetic processing unit or a signal control unit that operates at high speed, and generates high-frequency electromagnetic noise when controlling calculation or switch switching. The digital circuit part 24 becomes a digital logic circuit capable of transmitting the above-described digital signal, and various transmissions capable of transmitting digital data to the power supply 240 used for circuit driving and peripheral devices of the circuit board device 2 Interface 241.

  The shielding metal frame 20 is made of a metal material having good conductivity, and the structure is divided into a plurality of division frames 202 corresponding to the ground circuit 231 between the outer frame 201 and the high-speed units 230 surrounding the periphery. Therefore, a plurality of accommodation spaces 230 are formed. Further, since the bottoms of the external frame 201 and the dividing frame 202 are bonded so as to be in mutual contact with the ground circuit 231 around each high-speed unit 230, the electrical characteristics of the shielding metal frame 20 are the effects of the ground potential. Is equivalent to Further, the height of the shielding metal frame 20 is slightly higher than the height of any electronic unit disposed on the high-frequency circuit portion 23. These high speed units 230 are arranged in the accommodating portion 203 so as to correspond to each other separately.

  The analog circuit board 22 is divided into an upper surface 220 and a lower surface 221. The upper surface 220 has the above-described analog circuit and electronic unit 222 necessary for digital logic circuit operation. Since the lower surface 221 is electrically connected to a ground circuit in the circuit and is bonded so as to contact the outer frame 201 of the shielding metal frame 20 and the top of the dividing frame 202, the shielding metal frame 20 is It is fixed between the lower surface 221 of the analog circuit board 22 and the upper surface 210 of the main circuit board 21.

  Since the shielding metal frame 20 is bonded and fixed to the two circuit boards 21 and 22 by a method using conductive adhesive or soldering, the two circuit boards 21 and 22 are supported in a stable manner. In addition, the high-speed unit 230 is hermetically sealed so as to be accommodated in the accommodating portion 230, thereby inducing all high-frequency electromagnetic noise generated under the condition that the high-speed unit 230 performs high-speed operation processing to the ground potential. It is possible. Therefore, there is no problem that high-frequency electromagnetic noise leaks to the outside and affects analog signal transmission. In addition, since the circuit board device 2 can reduce the area occupied on the plane space by the method of overlapping the two circuit boards 21 and the circuit board 22, it increases the available area in the entire circuit arrangement, It is possible to increase the number of circuit board arrangement steps efficiently.

  Furthermore, even if a large number of the high-speed units 230 described above must be arranged in the circuit but cannot be accommodated in the area of the lower-layer main circuit board 21, they are stacked upward without increasing the area of the main circuit board 21. Can be solved. As shown in FIG. 4, the circuit board device 3 according to the second embodiment of the present invention includes a main circuit board 30, a first shielding frame 31, a high-frequency circuit board 32, and a second shielding that overlap in order from the bottom to the top. It has a frame 33 and an analog circuit board 34.

The main circuit board 30, the first shielding frame 31, and the analog circuit board 34 are designed in the same manner as the functions of the main circuit board 21, the shielding metal frame 20, and the analog circuit board 22 in the above-described embodiment. Is omitted.
The high frequency circuit board 32 employs a circuit design similar to the high frequency circuit portion 23 of the main circuit board 21 described above, and is divided into an upper surface 320 and a lower surface 321 facing each other. The upper surface 320 includes a plurality of high-speed units 35 and a ground circuit 36 disposed so as to be distributed around the effective circuit portion of the high-speed units 35. The lower surface 321 is similar in function and structure to the lower surface 221 of the analog circuit board 22 described above, and is electrically connected to the ground potential in the circuit and bonded to the top of the first shielding frame 31 to be in mutual contact. Is done.

The second shielding frame 33 is similar in function and structure to the shielding metal frame 20 described above, and is fixed between the analog circuit board 34 and the high-frequency circuit board 32, and the high-frequency electromagnetic noise generated by the high-speed unit 322 is grounded. Can be guided to.
Therefore, as long as the circuit space is expanded by a method in which only the circuit board is overlapped upward with respect to the circuit board device 3, not only the effect of blocking electromagnetic interference can be exhibited, but also the size and technical restrictions. It is also possible to reduce the size of the electronic product to which the electronic unit is applied.

  It should be noted that electromagnetic interference in the surrounding environment of the circuit, for example, communication noise, electrostatic reaction in the air, etc. is taken into account, or a wireless device such as an antenna facility that outputs or receives a wireless analog signal is arranged. If necessary, the circuit board device 4 according to the third embodiment of the present invention is shown in FIGS. 5 to 7 in order to prevent a slight influence on the signal transmission of the analog circuit in the circuit board. The signal emission source 5 that may generate an electromagnetic wave that interferes with the electrical operation of the circuit board device 4 is provided in the vicinity thereof. The circuit board device 4 includes a main circuit board 41, a shielding metal frame 41, and an analog circuit board 42 that are stacked in order from the bottom to the top.

Since the main circuit board 40 has a high-frequency circuit part 43 and a digital circuit part 44 and is similar to the design of the main circuit board 21 described above, detailed description thereof is omitted.
The analog circuit board 42 is divided into an upper surface 420 and a lower surface 421 facing each other. Since the upper surface 420 mainly includes the electronic unit 45 that transmits digital signals, it is not necessary to consider that electromagnetic waves interfere with signal transmission. As shown in FIG. 6, the lower surface 421 mainly includes an electronic unit 46 that transmits an analog signal, and a ground circuit 460 that is electrically grounded is disposed on the periphery of the lower surface 421.

Since the shielding metal frame 41 is made of a conductive metal material, the lower edge is provided so as to correspond to the ground circuit 460 of the analog circuit board 42 and the ground circuit of the edge of the high-frequency circuit portion 43. The overall electrical characteristics are equivalent to the effect of ground potential. Further, as shown in FIG. 7, the metal plate 410 divides it into an upper shielding portion 411 and a lower shielding portion 412. Since the lower shielding part 412 has the same structure as that of the shielding metal frame 20 described above, any high frequency electromagnetic wave noise generated by the operation of the high frequency circuit part 43 can be induced to the ground potential. is there. Therefore, there is no problem that high frequency electromagnetic noise leaks to the outside. The upper shielding portion 411 does not have a divided structure, but the height thereof is slightly higher than the height of any electronic unit disposed on the lower surface 421 of the analog circuit board 42. Therefore, the electronic circuit surrounded by the ground circuit 460 is the upper layer. It is completely covered in the shielding part 411. Therefore, it exhibits a good electrostatic shielding effect against the peripheral electromagnetic noise generated by the signal emission source 5.
Since the above are only preferred embodiments of the present invention, it is intended that equivalent changes or modifications based on the specification and claims of the present invention belong to the claims of the present invention.

It is a schematic diagram which shows the circuit of the conventional circuit board with an electromagnetic wave interference suppression function. It is a schematic diagram which shows the apparatus of the conventional circuit board with an electromagnetic wave interference suppression function. 1 is an exploded perspective view showing a circuit board device for preventing electromagnetic interference according to a first embodiment of the present invention. FIG. 5 is an exploded perspective view illustrating a circuit board device for preventing electromagnetic interference according to a second embodiment of the present invention. FIG. 6 is an exploded perspective view showing a circuit board device for preventing electromagnetic interference according to a third embodiment of the present invention. It is a schematic diagram which shows the circuit located in the lower surface of the analog circuit board of the circuit board apparatus for electromagnetic wave interference prevention by 3rd Example of this invention. It is a partial perspective view after the combination of the circuit board apparatus for electromagnetic wave interference prevention by the 3rd example of the present invention.

Explanation of symbols

  2 circuit board device, 3 circuit board device, 4 circuit board device, 5 signal emission source, 20 shielding metal frame, 21 main circuit board, 22 analog circuit board, 23 high frequency circuit part, 24 digital circuit part, 30 main circuit board 31 First shielding frame, 32 High frequency circuit board, 33 Second shielding frame, 34 Analog circuit board, 35 High speed unit, 36 Ground circuit, 40 Main circuit board, 41 Metal frame for shielding, 42 Analog circuit board, 43 High frequency circuit Part, 44 Digital circuit part, 45 Electronic unit, 46 Electronic unit, 201 External frame, 202 Dividing frame, 203 Housing space, 210 Upper surface, 211 Lower surface, 220 Upper surface, 221 Lower surface, 222 Electronic unit, 230 High speed Unit, 231 ground circuit, 240 power supply, 41 transmission interface, 320 on the surface 321 beneath the surface, 410 the metal plate, 411 an upper shielding portion, 412 lower shielding portion 420 on the surface, 421 lower surface, 460 ground circuit

Claims (10)

At least two circuit boards that overlap each other, each circuit board having an electronic circuit, of which the first circuit board has at least one high-speed unit, and the high-speed unit generates high-frequency electromagnetic noise in the surrounding environment. At least two circuit boards overlapping each other that may emit and generate electromagnetic interference (EMI) to the electronic circuit;
At least one shielding frame composed of a conductive metal material, sandwiched between two circuit boards and electrically connected to the ground potential of the circuit board;
The high-speed unit is disposed in the shielding frame, and the shielding frame can guide the electromagnetic wave interference to the ground potential by connecting and fixing two adjacent circuit boards and completely covering the high-speed unit. A circuit board device for electromagnetic wave interference prevention.   The circuit board device for electromagnetic wave interference prevention according to claim 1, wherein the second circuit board has an analog circuit disposed on the first circuit board and capable of transmitting an analog signal.   The second circuit board is divided into an upper surface and a lower surface facing each other, the upper surface has an electronic unit capable of transmitting an analog signal, and the lower surface is electrically connected to a ground potential. The circuit board device for electromagnetic wave interference prevention according to 2.   The first circuit board includes a high-frequency circuit part, the high-frequency circuit part has a plurality of high-speed units and a ground circuit, and the ground circuit is arranged so as to surround the periphery of the high-speed unit. The circuit board device for electromagnetic wave interference prevention according to 2.   The shielding frame has one outer frame surrounding the periphery and a plurality of dividing frames, and the dividing frames are provided so as to separately correspond to the ground circuits between the high-speed units, and can accommodate the high-speed units. 5. The circuit board device for preventing electromagnetic interference according to claim 4, wherein an accommodating space is formed.   The second circuit board is divided into an upper surface and a lower surface facing each other, the upper surface has an electronic unit capable of transmitting a digital signal, the lower surface has an electronic unit capable of transmitting an analog signal, and a peripheral edge of the lower surface The circuit board device for electromagnetic wave interference prevention according to claim 2, further comprising a ground circuit that is grounded in potential.   The shielding frame has a conductive metal plate that divides the space inside the shielding frame into an upper shielding portion and a lower shielding portion, and an electronic unit on the lower surface of the second circuit board is disposed in the upper shielding portion, The circuit board device for preventing electromagnetic interference according to claim 6, wherein the high-speed unit is disposed in a lower shielding portion.   The circuit board device has three circuit boards and two shielding frames, the two shielding frames are separately arranged between two adjacent circuit boards, and the second circuit board is arranged on the first circuit board. The third circuit board is disposed on the second circuit board, the second circuit board has at least one high-speed unit on the surface adjacent to the third circuit board, and the third circuit board can transmit an analog signal. The electromagnetic interference prevention circuit device according to claim 1, further comprising an analog circuit.   The third circuit board is divided into an upper surface and a lower surface facing each other, the upper surface has an electronic unit capable of transmitting an analog signal, and the lower surface is electrically connected to a ground potential. The circuit board device for electromagnetic wave interference prevention according to 8.   9. The circuit board device for preventing electromagnetic interference according to claim 8, wherein the second circuit has a plurality of high-speed units and a ground circuit, and the ground circuit is disposed so as to surround the periphery of the high-speed unit. .

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