CN101207967A - Circuit board structure capable of shielding electromagnetic wave interference - Google Patents

Abstract

The present invention discloses a circuit board structure capable of shielding electromagnetic wave interference, which is composed of a circuit substrate and a shielding unit, wherein the circuit substrate at least includes a ground layer, and a plurality of through holes that can be electrically connected to the ground layer are formed at each edge of the circuit substrate, and the spacing between the through holes is an integral multiple of the electromagnetic wavelength. Through the above-mentioned circuit board structure design, not only can the electromagnetic interference generated inside the circuit substrate be effectively absorbed, but also the wiring space can be relatively increased to save the production cost.

Description

Circuit board structure that shields electromagnetic interference

technical field

The invention relates to a circuit board structure, in particular to a circuit board structure capable of shielding electromagnetic wave interference.

Background technique

Due to the continuous improvement of the functions of electronic components, the update speed of electronic products has been accelerated, performance has been improved and portable development has also brought many electromagnetic compatibility problems, resulting in electromagnetic interference (Electro Magnetic Interference, EMI), and these electromagnetic Interference usually occurs during the design process of a printed circuit board (PCB), and most of it occurs in the edge area of the printed circuit board.

In order to shield the above-mentioned electromagnetic interference, it is conventional to increase the width of the ground layer in the circuit board in all directions of the PCB board plane, so as to absorb more electromagnetic interference generated by the signal lines of other substrates in the circuit board. Refer to Figure 1 and Figure 2 together, wherein, Figure 1 is a schematic diagram showing the simulation of electromagnetic interference between the power layer and the ground layer in the circuit board, which is based on the power layer that is most likely to generate electromagnetic interference in each substrate example. As shown in the figure, electromagnetic interference is generated between the power plane and the ground plane in the edge area of the circuit board. In order to improve the above deficiency, the current method is to increase the relative width of the ground layer by extending the ground layer outward relative to other signal routing areas, or relatively reducing the signal line routing area on the circuit board (that is, as shown in the figure 2), so that electromagnetic interference is absorbed by the ground layer. However, if this method is to achieve the complete absorption of the electromagnetic interference by the ground layer, the relatively increased width of the ground layer will be a rather large value. The above-mentioned method will undoubtedly waste a lot of available space and seriously affect the wiring of the entire circuit board. area.

There is also a way to absorb the electromagnetic interference generated inside the circuit board by adding capacitive elements in the circuit board. However, since the size of the added capacitor and its placement in the circuit board need to be calculated, it not only affects The production efficiency of the circuit board is reduced, and the production cost is also greatly increased. In addition, as the layout of the circuit design changes, the generated electromagnetic interference capability will also change accordingly. However, because the above method is relatively rigid and lacks flexibility, the actual operation is relatively inconvenient.

In addition, compared with the above-mentioned prior art, there are more effective methods for shielding the above-mentioned electromagnetic interference, such as: changing the layer structure of the circuit substrate to achieve the purpose of shielding the electromagnetic interference, specifically, by connecting the signal line The wiring is distributed on the inner layer of the circuit board, and the ground layer is changed to an outer layer to cover all signal layers. Although this method can effectively absorb electromagnetic interference, the above-mentioned circuit board structure will inevitably cause a large increase in production costs, and all signal lines are distributed in the inner layer of the circuit board. For circuit boards with a slightly higher complexity, The possibility of its realization is very small, and it may even lead to the dilemma of not being able to work. Another example is the method of reducing electromagnetic interference by setting multi-point grounding to suppress the potential difference generated by the ground layer in the circuit board when the return current flows. to reduce electromagnetic interference. However, the above method is only used to solve the electromagnetic interference caused by the potential difference, and has no suppression effect on the electromagnetic interference caused by other factors.

To sum up, how to overcome the various deficiencies of the above-mentioned prior art, and then provide a circuit board structure that can more effectively shield electromagnetic interference, can not only relatively increase the wiring space, but also save production costs, is actually an urgent problem to be solved at present. subject.

Contents of the invention

In view of the above-mentioned shortcomings of the prior art, the main purpose of the present invention is to provide a circuit board structure that can more effectively shield the electromagnetic interference generated inside the circuit substrate.

Another object of the present invention is to provide a circuit board structure capable of shielding electromagnetic interference, which can relatively increase wiring space and save manufacturing cost.

To achieve the above and other related objectives, the present invention provides a circuit board structure capable of shielding electromagnetic interference (EMI). The circuit board structure capable of shielding electromagnetic wave interference of the present invention is composed of a circuit substrate including at least one ground layer and a masking unit composed of a plurality of through holes arranged in a predetermined area of the circuit substrate, and in Metal material for electrically connecting with the ground layer is laid on the inner wall of each through hole. Wherein, the spacing value between the through holes is an integer multiple of the electromagnetic wavelength; the circuit substrate includes a plurality of signal layers, power layers and ground layers stacked interleavedly. In addition, the mask unit is arranged at the edge of the circuit substrate and one of the groups formed on the periphery of the signal wiring area with the same frequency inside the circuit substrate.

Compared with the prior art, the circuit board structure of the present invention can shield electromagnetic interference more effectively, and can relatively increase wiring space to save manufacturing cost.

Description of drawings

FIG. 1 is a schematic diagram of a simulation, which shows a schematic diagram of a simulation of electromagnetic interference generated between a power layer and a ground layer;

FIG. 2 is a schematic diagram of a simulation, which shows a conventional simulation schematic diagram of increasing the width of the ground layer to absorb more electromagnetic interference;

Fig. 3 is an internal structure diagram, which shows a schematic diagram of the internal structure of the circuit board structure of the present invention; and

FIG. 4 is a plan view showing a top plan view of an embodiment of the circuit board structure of the present invention.

Simple explanation of symbols

11 circuit substrate

111 ground layer

113 Through-hole spacing (D)

13a/13b mask unit

131 through hole

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific examples, and various modifications and changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

3 is a schematic diagram of the internal structure of the circuit board of the present invention. As shown in the figure, the circuit board structure capable of shielding electromagnetic interference of the present invention is composed of a circuit board 11 and a mask unit 13 disposed on the circuit board 11 .

The circuit substrate 11 at least includes a ground layer 111 . In this embodiment, the circuit substrate 11 may be composed of a plurality of signal layers (not shown), power layers (not shown) and ground layers 111 stacked interleavedly.

The mask unit 13 is formed by a plurality of through holes 131 disposed on the circuit substrate 11, and a metal material (not shown) for electrically connecting with the ground layer 111 is laid on the inner wall of each through hole 131. ). In this embodiment, by extending the ground layer 111 outward relative to the signal layer and the power layer (only a small distance is required), so that each of the through holes 131 can be electrically connected to the ground layer 111 . It should be noted that the distance between the through holes 131 on the circuit board 11 (i.e., the distance between the through holes 113) is an integer multiple of the wavelength of the electromagnetic wave. More specifically, the value of the distance between the through holes 113 is based on the electromagnetic In the principle of masking, it is calculated by the formula of the individual opening design of the area (not belonging to the continuous dense opening design), and the specific formula is as follows:

S=20lg(C/2LF)

Wherein, S represents the degree of attenuation (in this embodiment, the parameter value of the degree of attenuation is set artificially), C represents the propagation speed of electromagnetic waves (fixed value), F represents the frequency of electromagnetic waves, and L is equal to the above-mentioned through-hole spacing 113 value . In addition, since each of the through holes 131 is electrically connected to the ground layer 111 in the circuit substrate 11, so that the electromagnetic interference generated inside the circuit substrate 11 can be controlled by the above-mentioned through holes 131 design. Absorbed by the ground layer 111.

In a preferred embodiment, the electromagnetic wave frequency F is set to 1G; and the attenuation S is set to 20db (the attenuation can be changed according to actual needs). In addition, since the thickness of each substrate in the circuit board is relatively small, it can be ignored. Therefore, if the above-mentioned set value is substituted into the calculation formula shown above, the value of the through-hole spacing 113 (that is, the value of the L parameter) can be calculated. Equal to 15mm.

It should be noted that the mask unit 13 of the present invention can be disposed at each edge position of the circuit substrate 11 and the periphery of the signal wiring area with the same frequency inside the circuit substrate 11 (as shown in FIG. 4 ). In this embodiment, a group of through holes 131 are opened at intervals on the periphery of each signal wiring area A with the same frequency inside the circuit substrate 11, so as to form a mask unit 13a corresponding to each signal wiring area, so as to To achieve the effect of partial masking; then, for the whole circuit board 11, open through holes 131 at intervals at each edge of the circuit board 11, thereby forming a masking unit 13b relative to the whole circuit board 11, In this way, the electromagnetic interference generated inside the circuit substrate 11 can be covered by the above-mentioned structural design like a "birdcage", so as to play a good shielding effect.

To sum up, the circuit board structure of the present invention can more effectively shield electromagnetic interference, and can relatively increase the wiring space, so as to save manufacturing costs and make the wiring in the circuit board more stable.

The above-mentioned embodiments are only illustrative to illustrate the principles and effects of the present invention, and are not intended to limit the present invention. Any person skilled in the art can modify and change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be as listed in the appended claims.

Claims (5)

1. A circuit board structure capable of shielding electromagnetic wave interference, comprising: a circuit substrate including at least one ground plane; and The mask unit is composed of a plurality of through holes arranged on the circuit substrate, and a metal material for electrically connecting with the ground layer is laid on the inner wall of each through hole. 2. The circuit board structure according to claim 1, wherein the distance between the through holes is an integer multiple of the electromagnetic wavelength. 3. The circuit board structure according to claim 1, wherein the circuit substrate comprises a plurality of interleaved stacked signal layers, power layers and ground layers. 4. The circuit board structure according to claim 1, wherein the mask unit is disposed at an edge of the circuit substrate. 5 . The circuit board structure according to claim 1 , wherein the mask unit is disposed on the periphery of the signal wiring area with the same frequency inside the circuit substrate. 5 .

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