JP3629937B2 - Electromagnetic shielding structure and electronic device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic shielding structure and an electronic device using the same, and more particularly to an electromagnetic shielding structure used in a digital device or a high-frequency communication device and an electronic device using the same.
[0002]
[Prior art]
With the recent increase in frequency of digital devices and communication devices, the problem of interference with other circuits due to noise generated in one circuit within the device has increased, and countermeasures for preventing interference are urgently needed. .
[0003]
FIG. 8 shows a cross-sectional view of a conventional electromagnetic shielding structure for preventing noise propagation between one main surface and the other main surface of the substrate. In the electromagnetic shielding structure 1 of FIG. 8, the substrate 2 has a ground electrode layer 3 therein, and a wiring electrode 4 is formed on one main surface 2a and a wiring electrode 5 is formed on the other main surface 2b.
A ground electrode 6 is also formed on one main surface 2 a and the other main surface 2 b of the substrate 2, and is electrically connected to the ground electrode layer 3 through a via hole 7. The wiring electrode 4 and the wiring electrode 5 are connected to the substrate 2. They are connected by through holes 8 formed so as to penetrate therethrough.
On one main surface 2 a of the substrate 2, an electronic component 9 and a noise filter 10 constituting the first circuit are mounted on the wiring electrode 4 by solder 11. In addition, on the other main surface 2 b of the substrate 2, the electronic component 12 constituting the second circuit is mounted on the wiring electrode 5 by the solder 11.
The end of the substrate 2 is in contact with the metal chassis 13, and the substrate 2 is connected to the chassis 13 by electrically connecting the ground electrode 6 formed on both surfaces of the substrate 2 and the chassis 13 with the solder 11. It is fixed.
In FIG. 8, only one end of the board 2 is connected to the chassis 13. However, the board 2 is similarly connected to the chassis 13 in all the periphery of the board 2, and the inside of the chassis 13 is separated vertically by the board 2. ing.
Although not shown in FIG. 8, the chassis 13 has a top surface and a bottom surface, and the substrate 2 is provided in parallel to the top surface and the bottom surface of the chassis 13.
[0004]
Here, the electrical connection relationship of the electromagnetic shielding structure 1 is shown in FIG.
As shown in FIG. 9, the electronic component 9 is connected to the electronic component 12 via the noise filter 10 and the through hole 8.
Between the electronic components 9 and 12, the ground electrode layer 3 of the substrate 2 functions as a shielding plate except for the portion of the through hole 8 to prevent mutual electromagnetic interference.
[0005]
With this configuration, the one main surface 2a side and the other main surface 2b side of the substrate 2 are electromagnetically shielded. For example, noise generated in the electronic component 9 is suppressed by the noise filter 10 and It is difficult to reach.
[0006]
[Problems to be solved by the invention]
However, in the conventional electromagnetic shielding structure 1, noise generated in the electronic component 9 does not necessarily propagate only through the wiring electrode 4. For example, as shown by an arrow 14 in FIG. In some cases, the noise filter 10 may be bypassed to reach the through hole 8 directly.
Such noise cannot be removed by the noise filter 10, and there is a problem that it reaches the electronic component 12.
[0007]
The present invention aims to solve the above problems, and provides an electromagnetic shielding structure for preventing the propagation of noise between one main surface and the other main surface of a substrate, and an electronic device using the same. .
[0008]
[Means for Solving the Problems]
In order to achieve the above object, an electromagnetic shielding structure of the present invention comprises a chassis having a top surface, a bottom surface, and a side surface, and a substrate provided between the side surfaces of the chassis inside the chassis. A first circuit and a second circuit on the other main surface, and first and second through-holes formed in an upper portion and a lower portion with respect to the substrate position on the side surface of the chassis. And inserting one terminal of the first noise removing component into the first circuit and one terminal of the second noise removing component into the first circuit. The other terminals of the first and second noise elimination components are connected to each other outside the chassis.
[0009]
The electromagnetic shielding structure of the present invention is characterized in that the ground electrodes of the first and second noise elimination components are electrically connected to the chassis.
[0010]
In the electromagnetic shielding structure according to the present invention, an electric conductor is filled in a gap between the first and second through holes and the first and second noise eliminating components, and the electric conductor is used as the first electric conductor. And a ground electrode of the second noise eliminating component and the chassis are electrically connected.
[0011]
In addition, an electronic device according to the present invention is configured using the electromagnetic shielding structure described above.
[0012]
With this configuration, in the electromagnetic shielding structure of the present invention, it is possible to prevent the propagation of noise between the one main surface and the other main surface of the substrate.
In the electronic device of the present invention, a plurality of circuits do not become noise sources with respect to each other circuit, and each circuit can always function normally.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a cross-sectional view of an embodiment of the electromagnetic shielding structure of the present invention.
In FIG. 1, parts that are the same as or equivalent to those in FIG.
[0014]
In the electromagnetic shielding structure 20 of FIG. 1, a first through hole 21 and a second through hole 22 are formed in the upper part and the lower part with respect to the board 2 of the chassis 13 in the vicinity of the portion where the chassis 13 and the board 2 are connected. Has been.
The first through hole 21 and the second through hole 22 are inserted with a through capacitor 23 as a first noise eliminating component and a through capacitor 24 as a second noise eliminating component, respectively.
The ground electrodes on the side surfaces of the feedthrough capacitors 23 and 24 are electrically connected and fixed to the chassis 13 by the solder 1.
The lead pin 23a, which is one terminal of the feedthrough capacitor 23, is connected to the wiring electrode 4 formed on the one main surface 2a of the substrate 2, and the lead pin 24a, which is one terminal of the feedthrough capacitor 24, is connected to the other main surface 2b of the substrate 2. The lead pins 23 b and 24 b that are connected to the formed wiring electrode 5 and are the other terminals of the feedthrough capacitors 23 and 24 are electrically connected to each other outside the chassis 13.
[0015]
Here, FIG. 2 shows an electrical connection relationship of the electromagnetic shielding structure 20.
As shown in FIG. 2, the electronic component 9 once goes out of the chassis 13 through the feedthrough capacitor 23 and then enters the chassis 13 again through the feedthrough capacitor 24 and is connected to the electronic component 12. .
The ground electrodes of the feedthrough capacitors 23 and 24 are electrically connected to the chassis 13.
[0016]
With this configuration, only the path passing through the feedthrough capacitors 23 and 24 connects the one main surface 2a and the other main surface 2b of the substrate 2.
In this case, for example, noise generated in the electronic component 9 is suppressed when passing through the feedthrough capacitor 23, and also suppressed when passing through the feedthrough capacitor 24, and hardly reaches the electronic component 12.
Therefore, noise as in the conventional example does not directly reach the other main surface 2b from the one main surface 2a of the substrate 2 via the air.
As a result, in the electromagnetic shielding structure 20 of the present invention, it is possible to prevent the propagation of noise between the one main surface 2a and the other main surface 2b of the substrate 2.
[0017]
Although noise coming from the outside of the chassis 13 is sometimes received by the lead pins 23b and 24b of the feedthrough capacitors 23 and 24, this is also suppressed when passing through the feedthrough capacitors 23 and 24, and noise to the electronic components 9 and 12 It is hard to become.
[0018]
In FIG. 3, sectional drawing of the reference example 1 for demonstrating the electromagnetic shielding structure of this invention is shown. In FIG. 3, the same or equivalent parts as in FIG.
[0019]
In the electromagnetic shielding structure 30 of FIG. 3, a metal collar portion 31 is integrally provided with the chassis 13 in parallel with the upper surface and the bottom surface (not shown) of the chassis 13 from the inner surface of the chassis 13.
Further, the end portion of the substrate 2 is connected to the flange portion 31 by electrically connecting the ground electrode 6 formed on the other main surface 2 b of the substrate 2 and the flange portion 31 with the solder 11.
A through hole 32 is formed in the collar portion 31, and a through capacitor 33, which is a noise removing component, is inserted into the through hole 32.
The lead pin 33a, which is one terminal of the feedthrough capacitor 33, is connected to the wiring electrode 4 formed on the one main surface 2a of the substrate 2, and the lead pin 33b, which is the other terminal of the feedthrough capacitor 33, is connected to the other main surface 2b of the substrate 2. It is connected to the formed wiring electrode 5.
In FIG. 3, only one end of the substrate 2 is connected to the collar portion 31, but the substrate 2 is connected to the chassis 13 directly or via the collar portion 31 around the substrate 2, The inside of the chassis 13 is separated vertically by the collar portion 31.
[0020]
Here, FIG. 4 shows an electrical connection relationship of the electromagnetic shielding structure 30.
As shown in FIG. 4, the electronic component 9 is connected to the electronic component 12 via the feedthrough capacitor 33. The ground electrode of the feedthrough capacitor 33 is electrically connected to the collar portion 31.
[0021]
With this configuration, only the path passing through the feedthrough capacitor 33 connects the one main surface 2a and the other main surface 2b of the substrate 2.
In this case, for example, noise generated in the electronic component 9 is suppressed when passing through the feedthrough capacitor 33 and hardly reaches the electronic component 12.
Therefore, noise as in the conventional example does not directly reach the other main surface 2b from the one main surface 2a of the substrate 2 via the air.
As a result, in the electromagnetic shielding structure 30 of the present invention, it is possible to prevent the propagation of noise between the one main surface 2a and the other main surface 2b of the substrate 2.
[0022]
In FIG. 5, sectional drawing of the reference example 2 for demonstrating the electromagnetic shielding structure of this invention is shown. In FIG. 5, parts that are the same as or equivalent to those in FIG.
[0023]
In the electromagnetic shielding structure 40 of FIG. 5, the electric conductor 41 is filled between the inner surface of the through-hole 32 of the collar portion 31 and the ground electrode of the through-capacitor 33. The ground electrode and the collar portion 31 are electrically connected.
[0024]
With this configuration, the gap between the through-hole 32 of the collar portion 31 and the through-capacitor 33 is completely eliminated by the electric conductor 41, and the one main surface 2a side and the other main surface 2b side of the substrate 2 are eliminated. It is possible to more effectively electromagnetically shield the gap and prevent the propagation of noise between the one main surface 2a and the other main surface 2b of the substrate 2.
[0025]
Here, the case where the electric conductor 41 is filled in the gap between the feedthrough capacitor 33 and the collar portion 31 in FIG. 3 has been described, but the electric conductor is placed in the gap between the feedthrough capacitors 23 and 24 and the chassis 13 in FIG. Even in the case of filling, the same action and effect can be obtained.
[0026]
In each of the above embodiments and the reference example, the feedthrough capacitor is used as the noise removing component. However, this may be another noise filter or the like.
When a noise filter is used, a low-pass filter is generally used. However, depending on the type of noise that is desired to prevent propagation, a band-pass filter, a high-pass filter, and a band elimination filter (including a notch filter) It does not matter.
Further, the shape is not necessarily limited to a cylindrical shape such as a feedthrough capacitor.
[0027]
In FIG. 6, sectional drawing of the reference example 3 for demonstrating the electromagnetic shielding structure of this invention is shown. 6, parts that are the same as or equivalent to those in FIG. 3 are given the same reference numerals, and descriptions thereof are omitted.
[0028]
In the electromagnetic shielding structure 50 of FIG. 6, the first circuit including the electronic component 9 and the second circuit including the electronic component 12 are both digital circuits, and the through hole 32 of the collar portion 31 has a photo as a noise removing component. A coupler 51 is inserted.
An input terminal 51 a which is one terminal of the photocoupler 51 is a lead wire 52 on the wiring electrode 4 formed on one main surface 2 a of the substrate 2, and an output terminal 51 b which is the other terminal of the photocoupler 51 is the other terminal of the substrate 2. The lead wires 53 are connected to the wiring electrodes 5 formed on the main surface 2 b, respectively, and are fixed with solder 11.
Here, the input terminal 51a side of the photocoupler 51 is the photodiode side, the output terminal 51b side is the phototransistor side, and the signal is transmitted in one way from the input terminal 51a side to the output terminal 51b side.
[0029]
In the electromagnetic shielding structure 50 configured as described above, even if high-frequency noise is superimposed on the digital signal output from the electronic component 9, if the level is low, the threshold of the photocoupler 51 is not reached. It does not reach the electronic component 12 side.
Further, since the electrical pulse of the digital signal is once converted into an optical pulse and transmitted, there is no electrical connection of the signal line between the one main surface 2a side and the other main surface 2b side of the substrate 2. , Noise removal efficiency is increased.
In this way, between the one main surface 2a side and the other main surface 2b side of the substrate 2 is more effectively electromagnetically shielded, and between the one main surface 2a and the other main surface 2b of the substrate 2 Noise propagation can be prevented.
[0030]
When a photocoupler is used as a noise removal component, the signal flow is one-way. Therefore, if there is a signal flow in the reverse direction, it is necessary to separately provide a photocoupler in the reverse direction as necessary.
[0031]
FIG. 7 shows a cross-sectional view of one embodiment of the electronic device of the present invention.
The electronic device 60 shown in FIG. 7 is a device incorporating both a digital circuit portion and an analog power supply circuit portion, such as a computer.
[0032]
In FIG. 7, the electronic device 60 includes a metal box-shaped chassis 61, a collar 62 projecting in parallel from the inner surface of the chassis 61 to the top and bottom surfaces of the chassis 61, and one end connected to the collar 62. The board 63 provided so as to divide the space inside the chassis 61 together with the collar portion 62 into the upper and lower sides, the digital circuit 64 that is the first circuit formed on one main surface of the board 63, and the board 63 The switching power supply circuit 65, which is a second circuit formed on the other main surface, and a feedthrough capacitor 66 penetrating the collar portion 62 are included.
The substrate 63 has a ground electrode layer as an inner layer, and this ground electrode layer is electrically connected to the chassis 61 and the collar portion 62.
When the electronic device 60 is compared with the electromagnetic shielding structure 30 of FIG. 3, the substrate 63 is the substrate 2, the digital circuit 64 is the electronic component 9, the switching power supply circuit 65 is the electronic component 12, and the feedthrough capacitor 66 is the feedthrough capacitor 33. It corresponds to.
[0033]
By configuring the electronic device 60 in this way, when the DC voltage generated by the switching power supply circuit 65 on the other main surface of the substrate 63 is supplied to the digital circuit 64 formed on the one main surface of the substrate 63, switching is performed. Noise generated in the power supply circuit 65 can be cut by the feedthrough capacitor 66 so that it does not reach the digital circuit 64.
Thus, in the electronic device 60, the switching power supply circuit 65 can function normally without the switching power supply circuit 65 becoming a noise source for the digital circuit 64.
[0034]
Note that FIG. 7 shows an electronic device such as a computer for preventing the propagation of noise from an analog circuit to a digital circuit. However, the present invention is not limited to this. Similarly, it is also effective in the case of separating two high-frequency circuits that are two analog circuits that are likely to generate noise or are susceptible to noise.
Although the electronic device using the electromagnetic shielding structure shown in FIG. 3 has been described here, the electronic device using the electromagnetic shielding structure shown in FIGS. be able to.
[0035]
【The invention's effect】
According to the electromagnetic shielding structure of the present invention, the board on which the first and second circuits are formed on the one main surface and the other main surface is provided in the chassis in parallel with the upper surface and the bottom surface of the chassis. Through holes are provided in the upper and lower portions to insert the first and second noise elimination components, one terminal of the first noise elimination component is connected to the first circuit, and one terminal of the second noise elimination component is Propagation of noise between one main surface and the other main surface of the board by connecting to the second circuit and connecting the other terminals of the first and second noise elimination components outside the chassis. Can be prevented.
[0036]
Further, according to the electronic device of the present invention, by using the electromagnetic shielding structure described above, a plurality of circuits do not become noise sources with respect to each other, and each circuit can always function normally. it can.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of an electromagnetic shielding structure of the present invention.
2 is a diagram showing an electrical connection relationship of the electromagnetic shielding structure of FIG. 1;
FIG. 3 is a cross-sectional view of Reference Example 1 for explaining the electromagnetic shielding structure of the present invention.
4 is a diagram showing an electrical connection relationship of the electromagnetic shielding structure of FIG. 3;
FIG. 5 is a cross-sectional view of Reference Example 2 for explaining the electromagnetic shielding structure of the present invention.
FIG. 6 is a cross-sectional view of Reference Example 3 for explaining the electromagnetic shielding structure of the present invention.
FIG. 7 is a cross-sectional view showing an embodiment of an electronic device of the present invention.
FIG. 8 is a cross-sectional view showing a conventional electromagnetic shielding structure.
9 is a diagram showing an electrical connection relationship of the electromagnetic shielding structure of FIG.
[Explanation of symbols]
2 ... Substrate 2a ... One main surface 2b ... Other main surface 3 ... Ground electrode layer 9 ... Electronic component (first circuit)
12 ... Electronic component (second circuit)
20, 30, 40 ... electromagnetic shielding structure 21 ... first through hole 22 ... second through hole 23, 24, 33 ... through capacitor (noise removing component)
32 ... Through-hole 41 ... Electrical conductor 60 ... Electronic device

Claims (4)

A chassis having a top surface, a bottom surface, and a side surface, and a substrate provided between the side surfaces of the chassis inside the chassis, wherein the substrate has first and second circuits on one main surface and the other main surface. The first and second through holes are formed in the upper and lower portions with respect to the board position on the side surface of the chassis, and the first and second noise removing components are inserted into the first and second through holes. One terminal of the first noise eliminating component is connected to the first circuit, and one terminal of the second noise eliminating component is connected to the second circuit, respectively, and the first and second noises are connected. An electromagnetic shielding structure, wherein the other terminals of the removal component are connected to each other outside the chassis. 2. The electromagnetic shielding structure according to claim 1, wherein ground electrodes of the first and second noise eliminating components are electrically connected to the chassis. The electric conductors are filled in the gaps between the first and second through holes and the first and second noise eliminating components, respectively, and the electric conductors are grounded electrodes of the first and second noise eliminating components. The electromagnetic shielding structure according to claim 1, wherein the electromagnetic shielding structure is electrically connected to the chassis. An electronic device comprising the electromagnetic shielding structure according to claim 1.

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