JP3295862B2 - Radio wave countermeasure pattern of multilayer printed circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave countermeasure pattern for a multilayer printed board.

[0002]

2. Description of the Related Art FIG. 4 is a schematic diagram for explaining the structure of a conventional multilayer printed board 1. FIG. 4 (A) is an overall view, and FIG. 4 (B) is a cross-sectional view of a main part (portion where a through hole is formed). The multilayer printed board 1 has a first layer (surface layer) L1 and a second layer (inner layer) L2.
And a third layer (inner layer) L3 and a fourth layer (surface layer) L4. The pattern of each layer is connected via a through hole 2. 4B shows an example in which all layers L1 to L4 are connected, and the right side shows an example in which the first layer L1 and the third layer L3 are connected.

Examples of general patterns of each layer are as follows. Fourth layer L4: Signal line pattern (mainly horizontal pattern) Third layer L3: 5V power supply layer Second layer L2: SG (ground) layer First layer L1: Signal line pattern (mainly vertical) FIG. 5 shows a specific example of each layer pattern.

FIG. 5A shows an example of a pattern of the first layer L1, FIG. 5B shows an example of the second layer L2 (SG solid pattern), and FIG. 5C shows a pattern of the third layer L3. (5V solid pattern), and FIG. 5D shows an example of a pattern of the fourth layer L4. In the figure, a white circled through hole indicates that the layer is not connected, and a black circled through hole indicates that the layer is connected. An IC 3 and an LSI 4 are mounted on the fourth layer L4. FIG. 6 shows a circuit diagram of the LSI 4. In the figure, reference numeral 5 denotes a bypass capacitor, and the fourth layer L4
Mounted on top.

[0005]

In meeting various radio standards for digital equipment and the like using this kind of multilayer printed board, there have been the following problems conventionally. That is, high-frequency noise generated from the printed board is transmitted to the connected cable or the like, or is transmitted by causing capacitive coupling to the cable or the like close to the printed board, and finally the cables become antennas and emit noise. .

In order to prevent this, measures have been taken to add a ferrite core to the cable or shield the cable, but all of these have problems of high cost and manufacturability. Also, as a measure to reduce the noise of the printed circuit board itself, add filter components to the signal line of the noise source,
Printed board ground (SG) and equipment ground (FG)
Or short-circuiting the capacitor or taking measures to prevent high-frequency connection using a capacitor, but neither was a fundamental solution.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a radio wave countermeasure pattern for a multilayer printed circuit board which can prevent noise from being scattered from a mounted component generating high frequency noise to the surroundings.

[0008]

In order to achieve the above object, the present invention provides a multilayer printed circuit board having a power supply layer and a ground layer as inner layers, and a component for generating high frequency noise mounted on a surface thereof. Each of the component connection parts of the layer should be separated so that noise is not
Independent and separate in the same layer and separate ground
Layers and separated power layers are separated by filters.
And a connection .

[0009]

By separating mounted components that generate noise from others, high-frequency noise generated from the printed board itself can be fundamentally reduced, and as a result high-frequency noise radiated from the entire apparatus can be reduced. This eliminates the need for expensive ferrite cores and cable shields.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 2, the multilayer printed board 11 of this embodiment has surface layers 101 and 104 and an inner ground layer 10.
2, and a power supply layer 103. The pattern of each layer is as shown in the plan view of FIG. 1, and FIG.
1B shows the pattern of the ground layer 102 (solid pattern of SG), and FIG.
1 (D), and FIG. 1 (D) illustrates the pattern of the surface layer 104, respectively. On the surface layer 104, the same IC3, LSI4, bypass capacitor 5, 5V filter 12, and SG filter 13 as those of the related art are mounted.

The pattern of each of these layers is connected via a through hole as in the prior art, however, a white circle through hole indicates that it is not connected to that layer, and a black circle through hole indicates that it is connected to that layer. It means that there is.

As a countermeasure against radio waves of the multilayer printed board 11 having such a configuration, according to the present invention, in order to isolate only components that generate high-frequency noise from others, a solid pattern of an inner layer includes a power supply (5 V) and a ground (SG). Islands and make them independent in that layer. A filter component is inserted between the other 5 V or SG as needed. This will be described more specifically below.

In the surface layer, the noise generating component L
A through hole is provided inside SI4, and 5V and SG are connected to respective inner layers. The connection portion of the inner layer is island-shaped and is independently separated from the others. In the ground layer 102,
As shown in FIG. 1B, the island 15 is formed by providing the pattern deleted portion 14, and the island 15 is formed in the power supply layer 103.
As shown in FIG. 1C, the island 17 is formed by providing the pattern deleted portion 16.

5V filter 12 and SG filter 13
Are inserted between the inner layer islands 15, 17 and the other 5V, SG patterns, as shown in the LSI circuit diagrams of FIGS.

[0016]

As described above, according to the present invention, since the connection portion of the noise generating component in the inner layer pattern is separated independently from the others, the noise generating component is prevented from scattering the noise around. be able to.

[Brief description of the drawings]

1A and 1B are explanatory diagrams of a pattern of each layer of a multilayer printed board according to an embodiment of the present invention. FIG. 1A shows a pattern of a surface layer 101, FIG.
1C shows a pattern of the power supply layer 103, and FIG. 1D shows a pattern of the surface layer 104.

FIG. 2 is a sectional view of a multilayer printed board according to an embodiment of the present invention.

FIG. 3 is a circuit diagram of an LSI of a multilayer printed board according to an embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating the structure of a conventional multilayer printed board.

5A and 5B are explanatory diagrams of a pattern of each layer of a conventional multilayer printed board. FIG. 5A shows a pattern of a first layer L1, and FIG.
5 shows a pattern of the second layer L2, FIG. 5C shows a pattern of the third layer L3, and FIG. 5D shows a pattern of the fourth layer L4.

FIG. 6 is a circuit diagram of a conventional LSI of a multilayer printed board.

[Explanation of symbols]

 4 Components for Generating High Frequency Noise (LSI) 11 Multilayer Printed Board 12 5V Filter 13 SG Filter 15, 17 Island 101, 104 Surface Layer 102 Ground Layer 103 Power Supply Layer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 3/46 H05K 1/02

Claims (1)

(57) [Claims] 1. A multilayer printed circuit board having a power supply layer and a ground layer as inner layers, and a component generating high-frequency noise mounted on a surface thereof, wherein the component connection portions of the power supply layer and the ground layer do not disperse noise around. In the same layer , separate and separate , and separate and separate ground layers.
A radio wave countermeasure pattern for a multilayer printed circuit board, wherein separated power layers are connected to each other via a filter .