JP2003218541A - Circuit board structured to reduce emi - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a board structured to reduce the EMI to suppress the outward radiation of electromagnetic fields generated between a power supply layer and ground layers, by enclosing the electromagnetic fields by putting the power supply layer between the ground layers and, at the same time, connecting the end sections of the ground layers to each other. <P>SOLUTION: This substrate structured to reduce the EMI has the power supply layer, the ground layers holding the power supply layer from both sides, and a connector which connects the end sections of the ground layers to each other. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to EMI (Elec).
tro Magnetic Interferc
e: Electromagnetic interference) related to a structural substrate.

[0002]

2. Description of the Related Art Conventionally, in a board such as a printed wiring board on which electronic circuit parts are mounted, an electromagnetic field formed by a current component of a signal transmitted through a signal line in a signal wiring layer formed on the board. Causes electromagnetic noise. Therefore, in order to prevent the generation of electromagnetic noise, in the case of a board that has a digital circuit, such as a motherboard used in a computer, separate the power supply layer and the ground (ground or earth) layer from the signal wiring layer. A multi-layer structure of four or more layers formed by the above is adopted.

FIG. 2 is a sectional view showing a layer structure of a conventional substrate.

In the figure, 101 is a four-layer structure substrate such as a printed wiring board, 102 is a signal line in a signal wiring layer, that is, a signal trace, 103 is a planar conductor for ground as a ground layer, and 104 is a power supply layer. A sheet conductor for power supply 105 is a dielectric (insulator) which is made of resin, ceramics or the like and constitutes the main body of the substrate.

In this case, the four-layer structure substrate 101 has a structure composed of four layers of a signal wiring layer, a ground layer, a power supply layer, and a signal wiring layer in this order. The plane conductor 104 functions as a power feeding system. Further, since the ground layer and the power source layer made of the planar conductor are interposed between the signal wiring layers on both sides, even if the current component of the signal transmitted through the signal trace 102 forms the electromagnetic field, the electromagnetic wave is generated. The generation of noise is suppressed.

[0006]

However, in the conventional four-layer structure substrate 101, the ground plane conductor 103 and the power plane conductor 104 as the power supply layer and the ground layer are flat plates parallel to each other. Therefore, unnecessarily large electromagnetic noise is radiated to the outside from the peripheral edge of the four-layer structure substrate 101.

FIG. 3 is a diagram for explaining a state in which electromagnetic noise is radiated to the outside from an end portion of a conventional four-layer structure substrate.
In FIG. 3, the signal trace 102 and the dielectric 105 formed outside the planar conductor 103 for ground and the planar conductor 104 for power supply are omitted.

As shown in FIG. 3, in the conventional four-layer structure substrate 101, electromagnetic noise 106 is radiated from an end portion around the four-layer structure substrate 101 as indicated by an arrow 107. . This is because the current flowing through the wiring circuit of the power feeding system, the spread of the return current of the signal flowing through the signal trace 102, and the via hole (or via hole: Via) connecting the layers of the signal wiring layer, the ground layer and the power supply layer. -Hole), through hole (Throu
This is because the ground plane conductor 103 and the power plane conductor 104 are excited by gh-hole) or the like. The ground conductor 103 and the power conductor 104 are flat plates parallel to each other, that is,
Since it has the parallel plate structure, a cavity resonance occurs in the space between the ground plane conductor 103 and the power plane conductor 104, as indicated by a wavy line 108 having a large amplitude. Further, since the ends of the ground plane conductor 103 and the power plane conductor 104 are open at the peripheral edges of the four-layer structure substrate 101, the ground plane conductor 103 and the power plane plane are formed. The conductor 104 will behave like a slot antenna. for that reason,
At the resonance frequency of the cavity resonance, a large electromagnetic wave noise 106 is radiated from the peripheral end of the four-layer structure substrate 101 toward the outside, as indicated by an arrow 107.

In order to prevent the influence of the large electromagnetic noise 106, a bypass capacitor, an AC termination (combination of a capacitor and a resistor), noise countermeasure parts, etc. are used at the end of the four-layer structure substrate 101. It was necessary to dispose the shield device outside the four-layer structure substrate 101.

According to the present invention, the problems of the conventional substrate are solved, the power supply layer is sandwiched by the ground layers from both sides, and the end portions of the ground layers on both sides are connected to each other, whereby the power supply layer and the ground layer are connected. It is an object of the present invention to provide an EMI-reducing structure substrate capable of confining an electromagnetic field generated between a magnetic field and a magnetic field and suppressing the electromagnetic field from being radiated to the outside.

[0011]

Therefore, the E of the present invention is used for that purpose.
The MI reduction structure substrate has a power supply layer, a ground layer that sandwiches the power supply layer from both sides, and a connection body that connects end portions of the ground layer.

In another EMI reducing structure substrate of the present invention, it further has a signal wiring layer arranged outside the ground layer.

In still another EMI reducing structure substrate of the present invention, an electronic circuit component is connected to the signal wiring layer.

In still another EMI-reducing structure substrate of the present invention, the power supply layer, the ground layer, and the connecting body are made of planar conductors.

In still another EMI reducing structure substrate of the present invention, the connection body is formed so as to surround an end portion of the ground layer.

Still another EMI reducing structure substrate of the present invention is a multi-layer substrate having four or more layers.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an EMI according to an embodiment of the present invention.
It is sectional drawing which shows the layer structure of a reduction structure substrate.

In the figure, reference numeral 11 is an EMI reducing structure substrate used in an electronic device as a substrate such as a printed wiring board on which electronic circuit components are mounted. The EMI reducing structure substrate 11 is suitable for an electronic device that uses a digital circuit such as an information processing device such as a computer, but can be used for any electronic device.

The EMI reducing structure substrate 11 is
A signal trace 12 as a signal line in a signal wiring layer including a large number of electronic circuit components such as ICs, LSIs, resistors, capacitors, and a large number of signal wirings having a complicated shape connecting the electronic circuit components, and a ground plane as a ground layer. Conductor 13
a, a planar power source conductor 14 as a power source layer, and a dielectric 15 which is made of resin, ceramics or the like and constitutes the main body of the substrate. The EMI reducing structure substrate 11 is
Actually, it has a via hole, a through hole, etc. for electrically connecting the signal wiring layer, the ground layer and the power supply layer, but in the present embodiment, the electronic circuit component, a large number of signal wirings with complicated shapes, and a via hole are provided. , The through holes and the like are omitted, and the modeled one as shown in FIG. 1 will be described.

In this case, the EMI reducing structure substrate 11
Has a multi-layered structure including five layers in which a signal wiring layer, a ground layer, a power supply layer, a ground layer, and a signal wiring layer are arranged in this order. In addition, the planar conductor 1 for ground that constitutes the ground layer
The ends of 3a are connected to each other by a connecting planar conductor 13b as a connecting body. Here, the connecting planar conductor 13b is made of the same metal as the grounding planar conductor 13a, and is formed by plating. For example, when the planar conductor 13a for ground is made of copper, the planar conductor 13b for connection is formed by plating copper.
Is formed. In this case, an end portion of the two-layer ground conductor 13a serving as a ground layer is almost entirely connected so as to be surrounded by the connection conductor 13b. For example, when the EMI reducing structure substrate 11 has a rectangular plate shape as a whole, the four sides of the rectangle have a structure as shown in FIG. The connecting planar conductor 13b extends along the side. That is, the connecting planar conductor 13b is formed so as to surround the entire end portion around the EMI reducing structure substrate 11. It should be noted that the dielectric 15 may be arranged outside the connecting planar conductor 13b.

As described above, in the EMI reducing structure substrate 11, the ground plane conductor 13a as the ground layer.
However, by sandwiching the power source planar conductor 14 as a power source layer from both sides (the upper side and the lower side in the figure), the power source planar conductor 1
The end portions of the planar conductor 13a for ground on both sides of 4 are connected by the planar conductor 13b for connection. That is, the space formed between the ground plane conductors 13a on both sides is closed at the end by the connection plane conductor 13b, and the power plane conductor 14 is placed in the space whose ends are closed. Is trapped.

Next, the operation of the EMI reducing structure substrate having the above structure will be described.

FIG. 4 shows the EMI in the embodiment of the present invention.
It is a figure explaining the state where electromagnetic wave noise is radiated outside from the reduction structure substrate. In FIG. 4, the signal trace 12 and the dielectric 15 formed on both sides of the ground plane conductor 13a are omitted.

Here, a mechanism of radiating electromagnetic waves as electromagnetic noise to the outside will be described. First,
A four-layer structure substrate 101 having a structure composed of four layers of a signal wiring layer, a ground layer, a power supply layer, and a signal wiring layer in this order as described in "Prior Art" and "Problems to be Solved by the Invention". In the following, the radiation of the electromagnetic noise 106 generated by the resonance between the power supply layer and the ground layer will be described.

In this case, the planar conductor 103 for ground forming the ground layer and the planar conductor 104 for power supply forming the power supply layer in the four-layer structure substrate 101 have a parallel plate structure with open ends. Therefore, the space between the parallel flat plates composed of the ground plane conductor 103 and the power plane conductor 104 can be considered as a waveguide.
The electromagnetic field in the space between the parallel flat plates can be understood as the following equation (1), which is a wave equation showing the electromagnetic field in the internal region, and an open boundary 4
It can be expressed by the following equation (2) which defines the boundary condition at the peripheral edge of the layered structure substrate 101.

[0027]

[Equation 1]

Here, ∇ is the vector operator Nabla, k is the wave number vector, E _z is the z component of the electric field vector, and n is the outward unit normal line at the edge around the four-layer structure substrate 101 as an open boundary. Is a vector. In addition, ∇ ² _t in Expression (1) is defined by the following Expression (3).

[0029]

[Equation 2]

In this case, when the outer dimensions of the four-layer structure substrate 101 are equal to or more than a few fractions of the wavelength of the electromagnetic wave having the frequency to be analyzed, the influence of the outer dimensions. Cannot be ignored. Therefore, the resonance frequency fmn of the cavity resonance of the electromagnetic wave generated in the space between the parallel plates can be derived by the following equation (4).

[0031]

[Equation 3]

Here, a and b are vertical and horizontal external dimensions of the four-layer structure substrate 101, C ₀ is the speed of electromagnetic waves in a vacuum, that is, the speed of light, and ε _r is the ground plane conductor 103. It is the dielectric constant of the dielectric material 105 in the space between the parallel plates composed of the planar conductor 104 for power supply.

Then, in the space between the parallel plates,
As shown by the wavy line 108, when the cavity resonance of the electromagnetic wave occurs, a large electromagnetic field is generated inside the space. Furthermore, since the end portions of the planar conductor 103 for ground and the planar conductor 104 for power supply are open at the peripheral end portion of the four-layer structure substrate 101, the peripheral end portion of the four-layer structure substrate 101 is The electromagnetic field leaks out and is radiated as electromagnetic noise 106. In this case, in the electromagnetic field, the open end of the four-layer structure substrate 101 behaves like a magnetic wall, so that a magnetic current flows along the open surface of the end and the magnetic current is radiated. As a source, as shown in FIG. 3, radiation of electromagnetic noise 106 is generated.

Next, the electromagnetic field in the EMI reducing structure substrate 11 according to this embodiment will be described. Here, in the EMI reducing structure substrate 11, as shown in FIG. 4, the two ground plane conductors 13a forming the ground layer sandwich the power plane conductor 14 forming the power layer from both sides. Furthermore, the end portions of the ground plane conductor 13a on both sides of the power plane conductor 14 are connected to each other by the connection plane conductor 1.
They are connected to each other by 3b.

In this case, a space between the parallel flat plates composed of the ground plane conductor 13a and the power plane conductor 14 is formed on both sides of the power plane conductor 14. When the cavity resonance of the electromagnetic wave occurs in each of the spaces between the parallel plates as described above, the electromagnetic waves in the respective spaces behave so as to cancel out the resonance energies of each other. for that reason,
The cavity resonance of the electromagnetic wave generated in the space between the parallel plates is
As shown by the wavy line 18, it becomes extremely weak,
It becomes a state of being confined in the space.

Further, the connecting surface conductor 13b is formed so as to surround the entire end portion around the EMI reducing structure substrate 11, and the end portions of the ground surface conductor 13a are mutually connected by the connecting surface conductor 13b. It is connected. As a result, the space between the parallel flat plates formed on both sides of the power source planar conductor 14 is in a state in which the ends are closed. Therefore, the electromagnetic field generated by the cavity resonance of the electromagnetic wave in the space between the parallel plates is prevented from leaking out from the end of the EMI reducing structure substrate 11 and radiated, and the electromagnetic noise 16 radiated to the outside is: It is extremely weak as compared with the electromagnetic noise 106 radiated to the outside from the conventional four-layer structure substrate 101.

Further, the ground plane conductor 13a is arranged on both sides of the power plane conductor 14, and the ends of the ground plane conductor 13a are connected to each other by the connection plane conductor 13b. Therefore, the area of the conductor forming the ground layer is large. Therefore, signal trace 1
The return current of the signal flowing through 2 always flows through the ground layer, and is spread over the entire ground layer without being unevenly distributed at the end of the planar conductor 13a for ground.
Thereby, the emission of the electromagnetic noise 16 from the end of the EMI reducing structure substrate 11 is suppressed, and the emission of the electromagnetic wave from the entire EMI reducing structure substrate 11 is also suppressed.

Next, the EMI in the embodiment of the present invention.
An experimental example of the reduced structure substrate will be described.

FIG. 5 is a perspective view showing the surface structure of the comparative test substrate in the embodiment of the present invention, FIG. 6 is a diagram showing the radiated electric field intensity in the four-layer structure substrate in the embodiment of the present invention, and FIG. FIG. 8 is a diagram showing a radiated electric field intensity in the EMI reducing structure substrate according to the embodiment of the present invention, FIG. 8 is a diagram showing a magnetic field intensity distribution in the vicinity of the surface in the four-layer structure substrate according to the embodiment of the present invention, and FIG. 9 is a diagram showing the present invention. FIG. 10 is a diagram showing a magnetic field strength distribution near the back surface of the four-layer structure substrate in the embodiment, FIG. 10 is a diagram showing a magnetic field strength distribution near the front surface in the EMI reducing structure substrate in the embodiment of the present invention, and FIG.
FIG. 1 is a diagram showing a magnetic field strength distribution in the vicinity of the back surface of the EMI reduction structure substrate according to the embodiment of the present invention.

Here, an EMI reducing structure substrate 11 having a surface structure as shown in FIG. 5 and a cross-sectional structure as shown in FIG. 1 was manufactured, and for comparison,
A four-layer structure substrate 101 having a surface structure as shown in FIG. 5 and a cross-sectional structure as shown in FIG. 2 was produced. The outer dimensions of the EMI reducing structure substrate 11 and the four-layer structure substrate 101 are both 230 × 150.
[Mm].

In this case, in FIG. 5, reference numeral 22 is a signal trace, which comprises signal traces 22a and 22b formed on the front surface and a signal trace 22c formed on the back surface. Reference numeral 23 is a via hole penetrating the EMI reducing structure substrate 11 (four-layer structure substrate 101), which connects the signal trace 22a and the signal trace 22c.
3a, and signal trace 22b and signal trace 22c
It is composed of a via hole 23b that conducts with. The signal trace 22 is composed of the signal traces 22a, 22b and 2
The total length of 2c is 210 [mm] and the characteristic impedance is 50 [Ω].

Further, 24 is a signal input SMA connector connected to the end of the signal trace 22a, 25 is a terminal connecting electrode connected to the end of the signal trace 22b, and a large number of 26 are formed on the surface. It is a connecting electrode. The capacitance of the terminal connecting electrode 25 is 5 [pF].

Then, the EMI reducing structure substrate 1 having the above-mentioned structure
The radiative field strengths of the 1- and 4-layer structure substrates 101 were measured in an anechoic chamber.

Here, in FIG. 6, 4 measured as a comparative example is shown.
The frequency distribution of the radiation field intensity of the layer structure substrate 101 is shown. From FIG. 6, the radiated electrolytic strength of the four-layer structure substrate 101 is generally high, and is 60 in the frequency band around 300 [MHz] and the frequency band above 450 [MHz].
[DB] or more, about 310 [MHz] and about 630
It can be seen that there is a large peak at the frequency of [MHz]. And, the maximum value of the radiation field intensity is about 630.
It becomes 79.0 [dB] at the frequency of [MHz].

On the other hand, FIG. 7 shows the frequency distribution of the radiation electrolytic strength of the EMI reducing structure substrate 11 in the embodiment of the present invention. From FIG. 7, the radiated electrolysis intensity of the EMI reduction structure substrate 11 is lower than the radiated electrolysis intensity of the four-layer structure substrate 101, and in the frequency band of 700 [MHz] or less,
It can be seen that it is almost never higher than 50 [dB]. In addition, no large peak is generated in the entire band, and the maximum value of the radiated electrolytic strength is the same as that of the four-layer structure substrate 101.
Is much lower than the maximum value of 59.1 [dB].

From the measurement results shown in FIGS. 6 and 7,
In the EMI reducing structure substrate 11 according to the embodiment of the present invention, it is apparent that the radiated electrolytic strength is effectively suppressed as compared with the conventional four-layer structure substrate 101.

Subsequently, the EMI reducing structure substrate 1 having the above-mentioned structure
The near magnetic field strengths on the front surface and the back surface of the 1- and 4-layer structure substrate 101 were measured in an anechoic chamber.

Here, in FIG. 8, 4 measured as a comparative example is shown.
The distribution of the near magnetic field strength on the surface of the layer structure substrate 101 is shown. From FIG. 8, the near magnetic field strength on the surface of the four-layer structure substrate 101 is generally high, and a value of about 50 [dB] is obtained at a place other than the places corresponding to the signal traces 22a and 22b formed on the surface. You can see that there are many places to show. Note that the two large peaks in FIG. 8 are the signal traces 22a and 22b formed on the surface.
Since it is located at a location corresponding to
And 22b.

Further, FIG. 9 shows the distribution of the near magnetic field strength on the back surface of the four-layer structure substrate 101 measured as a comparative example. From FIG. 9, the near-field strength on the back surface of the four-layer structure substrate 101 is generally high, and even at a location other than the location corresponding to the signal trace 22c formed on the back surface, a location showing a value of 45 [dB] or more. It turns out that there are many. It should be noted that one large peak in FIG. 9 is located at a position corresponding to the signal trace 22c formed on the back surface, and thus it can be understood that the magnetic field is due to the signal trace 22c.

On the other hand, FIG. 10 shows the distribution of the near magnetic field strength on the surface of the EMI reducing structure substrate 11 according to the embodiment of the present invention. From FIG. 10, the near magnetic field strength on the surface of the EMI reduction structure substrate 11 is generally low, and a value of 40 [dB] or less is obtained at a place other than the places corresponding to the signal traces 22a and 22b formed on the surface. You can see that there are many places to show. Since the two large peaks in FIG. 10 are located at the positions corresponding to the signal traces 22a and 22b formed on the surface,
It can be seen that it is the magnetic field due to the signal traces 22a and 22b.

FIG. 11 shows the distribution of the near magnetic field intensity on the back surface of the EMI reducing structure substrate 11 according to the embodiment of the present invention. From FIG. 11, the magnetic field strength in the vicinity of the back surface of the EMI reduction structure substrate 11 is generally low, and even at a location other than the location corresponding to the signal trace 22c formed on the back surface, a location showing a value of 38 [dB] or less is obtained. It turns out that there are many. Note that one large peak in FIG. 11 is the signal trace 22c formed on the back surface.
Signal trace 22c from the location corresponding to
It can be seen that the magnetic field is due to.

From the measurement results shown in FIGS.
In the EMI reducing structure substrate 11 according to the embodiment of the present invention, the magnetic field strength is effectively suppressed in a place other than the places corresponding to the signal traces 22a, 22b and 22c, as compared with the conventional four-layer structure substrate 101. It is clear that

As described above, in the present embodiment, the EM
The planar conductor 13a for ground forming the ground layer of the I reduction structure substrate 11 is the planar conductor 1 for power supply forming the power supply layer.
4 are sandwiched from both sides, and the ends of the ground plane conductor 13a on both sides of the power plane conductor 14 are connected by the connection plane conductor 13b. That is, the space formed between the ground plane conductors 13a on both sides is closed at the end by the connection plane conductor 13b, and the power plane conductor 14 is placed in the space whose ends are closed. Is trapped.

Therefore, the electromagnetic waves generated in the space between the parallel flat plates formed between the planar conductor 14 for power supply and the planar conductor 13a for ground act so as to cancel out the resonance energies, and the cavity resonance occurs. It becomes extremely weak and is trapped in the space. Further, since the end portion of the space is closed by the connecting planar conductor 13b, it is possible to prevent the electromagnetic wave from leaking out from the end portion of the space to be emitted. Furthermore, E
Radiation of electromagnetic waves from the entire MI reduction structure substrate 11 can also be suppressed. Therefore, electromagnetic interference due to electromagnetic waves can be effectively reduced.

In addition, since it is not necessary to use components or devices that do not contribute to the function of the circuit, such as bypass capacitors and noise suppression components that have been conventionally used to suppress the influence of electromagnetic waves, the manufacturing cost of the substrate can be reduced. Can be reduced, and small size and high density mounting can be achieved.

In this embodiment, the outer two
The EMI reduction structure substrate 11 in which the power supply plane conductor 14 as one power supply layer is sandwiched between the ground plane conductors 13a as one ground layer has been described. A plurality of power supply layers, another ground layer, and a signal wiring layer may be provided between the two outer ground layers.

EM in the embodiment of the present invention
Since the I reduction structure substrate 11 can be applied to a general digital circuit, it can be easily and inexpensively applied to a general electronic device using a digital circuit such as an information processing device.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

[0059]

As described above in detail, according to the present invention, in the EMI reducing structure substrate, the power supply layer, the ground layer sandwiching the power supply layer from both sides, and the end portion of the ground layer are connected. It has a connecting body.

In this case, the space formed between the ground layers on both sides is closed at the end by the connecting body, and the ground layer is confined in the space whose end is closed. Therefore, the electromagnetic waves generated in the space between the parallel plates formed between the power supply layer and the ground layer behave so as to cancel out the resonance energies of each other, and the cavity resonance becomes extremely weak. Be trapped.

Further, since the end of the space is closed by the connector, it is possible to prevent the electromagnetic wave from leaking out from the end of the space and being radiated.
Furthermore, the emission of electromagnetic waves from the entire EMI reducing structure substrate can be suppressed.

Therefore, electromagnetic interference due to electromagnetic waves can be effectively reduced.

Further, since it is not necessary to use components or devices that do not contribute to the function of the circuit, such as bypass capacitors and noise countermeasure components that have been conventionally used to suppress the influence of electromagnetic waves, it is possible to reduce the manufacturing cost of the substrate. It is possible to reduce the size, and it is possible to achieve a small size and high density mounting.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a layer structure of an EMI reducing structure substrate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a layer structure of a conventional substrate.

FIG. 3 is a diagram illustrating a state where electromagnetic wave noise is radiated to the outside from an end portion of a conventional four-layer structure substrate.

FIG. 4 is a diagram illustrating a state in which electromagnetic noise is radiated from the EMI reducing structure substrate according to the embodiment of the present invention to the outside.

FIG. 5 is a perspective view showing a surface configuration of a comparative test substrate according to an embodiment of the present invention.

FIG. 6 is a diagram showing a radiated electric field intensity in a four-layer structure substrate according to an embodiment of the present invention.

FIG. 7 is a diagram showing a radiated electric field intensity in the EMI reducing structure substrate according to the embodiment of the present invention.

FIG. 8 is a diagram showing a magnetic field intensity distribution in the vicinity of the surface of the four-layer structure substrate according to the embodiment of the present invention.

FIG. 9 is a diagram showing a magnetic field strength distribution in the vicinity of the back surface of the four-layer structure substrate according to the embodiment of the present invention.

FIG. 10 is a diagram showing a magnetic field intensity distribution in the vicinity of the surface of the EMI reduced structure substrate according to the embodiment of the present invention.

FIG. 11 is a diagram showing a magnetic field strength distribution in the vicinity of the back surface of the EMI reduction structure substrate according to the embodiment of the present invention.

[Explanation of symbols]

11 EMI reduction structure substrate 13a Ground conductor for ground 13b Sheet conductor for connection 14 Surface conductor for power supply

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5E321 AA17 GG05                 5E338 AA03 CC01 CC04 CC06 CD03                       EE13                 5E346 BB02 BB03 BB04 BB07 CC01                       FF22 FF28 FF42 HH04 HH06                       HH40

Claims (6)

[Claims] 1. An EMI reducing structure comprising: (a) a power supply layer; (b) a ground layer sandwiching the power supply layer from both sides; and (c) a connecting body connecting end portions of the ground layer. substrate. 2. The EMI reducing structure substrate according to claim 1, further comprising a signal wiring layer disposed outside the ground layer. 3. The EMI reduced structure substrate according to claim 2, wherein an electronic circuit component is connected to the signal wiring layer. 4. The power supply layer, the ground layer, and the connection body,
The EMI-reducing structure substrate according to claim 1, comprising a planar conductor. 5. The EMI reducing structure substrate according to claim 1, wherein the connection body is formed so as to surround an end portion of the ground layer. 6. A multi-layer substrate having four or more layers.
The EMI-reducing structure substrate according to any one of 1.