JP2001177287A - Radiation noise suppressing tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress radiation noise generated from a substrate 1 or the like by preventing the problems of maintenance properties and heat from occurring with simple structure. SOLUTION: A VIA cap 21 (radiation noise-suppressing tool) for reducing EMI is used to suppress radiation noise that is generated at a discontinuous point 7 of impedance. The tool is composed of a shielding plate part 22 for suppressing radiation noise by slightly covering only a flange part 6B of a VIA 6 where radiation noise is generated, and a support part 23 for fixing the shielding plate part 22 to the VIA 6 for supporting, thus achieving the VIA cap 21 for reducing EMI with simple and compact structure, easily and surely suppressing radiation noise, and at the same time radiating heat being generated by an element or the like to the surrounding, and appropriately maintaining cooling efficiency. Also, since the shielding plate part 22 can be easily attached or detached, working efficiency in maintenance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation noise suppressor for suppressing radiation noise generated in a through hole (hereinafter referred to as "VIA") in a substrate on which an IC or the like is mounted.

[0002]

2. Description of the Related Art Generally, a substrate 1 on which an IC or the like is mounted is shown in FIG.
It is configured as shown in FIG. The signal wiring 2 is provided on the surface of the substrate 1, and the power supply layer 3 and the ground layer 4 are provided inside the signal wiring 2. The signal wiring 2 is also provided between the power supply layer 3 and the earth layer 4 according to the design. An insulating material 5 is provided between the signal wiring 2, the power supply layer 3 and the ground layer 4.
Is filled. Furthermore, V
An IA6 is provided. The VIA 6 has a cylindrical portion 6A provided to penetrate the substrate 1 from the front side to the rear side.
And a flange portion 6B provided with the upper and lower ends of the cylindrical portion 6A widened. A large number of VIAs 6 are provided on the substrate 1 as signal VIAs and power supply VIAs, and are appropriately connected to the signal wiring 2, the power supply layer 3, and the ground layer 4. Further, on the surface of the substrate 1, elements such as ICs are connected to the signal wiring 2 and the VIA 6.

In the substrate 1, an electric signal such as an IC is transmitted from a signal wiring 2 to another signal wiring 2 via a signal VIA 6, and at this time, the signal wiring 2 and the signal V
A connection portion with the IA 6 becomes a discontinuity point 7 of the impedance. At the discontinuity point 7 of the impedance, ringing containing a high frequency component in the electric signal is generated, which is one of the causes of the generation of radiation noise.

In addition, as the switching operation speed of the IC increases, a current containing a high frequency component flows through the power supply pin and the ground pin with respect to the impedance of the circuit, thereby generating power supply noise. Or a malfunction of the substrate or the device. Usually, in order to reduce the power supply noise, as shown in FIG. 3, a bypass capacitor 8 is mounted near (horizontally) the power supply pin and the ground pin of the IC. This bypass capacitor 8
The power supply layer 3 and the earth layer 4 are connected near the IC. That is, the power supply VIA 6C connected to the power supply layer 3 is
Is connected to one terminal of the bypass capacitor 8, and the power supply VIA 6 </ b> D connected to the ground layer 4 is connected to the other terminal of the bypass capacitor 8 via the pad 10. As a result, a predetermined voltage is supplied to the bypass capacitor 8 via the power supply vias 6C and 6D.

Also in this case, since the VIA 6C, 6D and the power supply layer 3, the ground layer 4, the pads 9, 10 and the like become the impedance discontinuity point 7, the power supply VIA 6C, 6
D generated radiation noise.

On the other hand, the front and back surfaces of the substrate 1 are coated with a resist 11, but the VIA 6 is only plated with solder 12. For this reason,
Radiation noise generated in VIA 6 was easily leaked to the outside.

Conventionally, in order to reduce such leakage of radiation noise to the outside, an EMI countermeasure method has been proposed in which the entirety of an IC, a substrate, or a device is shielded to suppress the leakage of radiation noise to the outside. Had been.

[0008]

However, the above-mentioned conventional method has the following problems.

(1) When the whole is shielded from an IC, a substrate, or the like in which radiated noise is generated, the scale is large.
It will be massive. In addition, when inspecting the inside for maintenance, it is necessary to remove the shield once attached and perform the work, and there is a problem that workability is poor.

(2) When shielding is performed on an IC, a board, or the like, heat tends to accumulate in the shielded portion, and the cooling efficiency is reduced. There is a problem.

An object of the present invention to solve the above problems is to provide a radiation noise suppressor having a simple structure and capable of suppressing radiation noise while preventing the occurrence of maintenance and heat problems.

[0012]

In order to achieve the above object, a radiation noise suppressor according to a first aspect of the present invention is a radiation noise suppressor for suppressing radiation noise generated at a discontinuity of impedance. It is composed of an insulator containing a magnetic material, and is composed of a shielding plate portion that covers only a portion where the radiated noise is generated and suppresses the radiated noise, and a supporting portion that fixes and supports the shielding plate portion to the above portion. It is characterized by having been done.

According to the above configuration, the shielding plate is fixedly supported by the supporting portion on the portion where the radiation noise is generated, so that the shielding plate covers only the portion to a small extent. Accordingly, the radiation noise can be easily and reliably suppressed by the radiation noise suppressor having a simple and compact structure. At this time, since the radiation noise suppressing device covers only a portion where the radiation noise is generated, the heat generated by the element and the like is released to the surroundings.

According to a second aspect of the present invention, there is provided the radiation noise suppressor according to the first aspect, wherein the shielding plate includes only a through-hole existing in a substrate on which an IC or the like is mounted, and Consisting of an EMI reducing VIA cap attached so as to cover one or both of its front surface and back surface, the supporting portion is integrally formed with the EMI reducing VIA cap and inserted into the through hole. And a support shaft for fixing and supporting the EMI reduction VIA cap on the front surface or the back surface of the through hole.

According to the above structure, the support shaft is inserted into the through hole of the substrate and attached to the EMI reducing VIA.
The cap is attached to cover only the through hole. Thus, the radiation noise suppressor having a simple and compact structure can easily and surely suppress the radiation noise, and can surely release the heat generated in the element and the like. Furthermore, the radiation noise suppressor can be easily attached / detached only by inserting / removing the support shaft into / from the through-hole of the substrate, so that the maintainability is greatly improved.

According to a third aspect of the invention, there is provided a method for soldering electronic components according to the first aspect of the present invention, wherein the supporting portion adheres the shielding plate portion to a portion where radiation noise is generated. It is characterized by being formed of an adhesive member that supports.

According to the above configuration, the shielding plate is fixedly supported on the above-mentioned portion by the adhesive member. As the adhesive member, an adhesive that is interposed between the shielding plate portion and the substrate and that joins and fixes the two, an adhesive tape that covers the shielding plate portion and is attached to the substrate is used. Note that, as the adhesive or the adhesive tape, an adhesive or the like having an adhesive force that can be peeled off during maintenance is used.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A radiation noise suppressor according to the present invention will be described below with reference to the accompanying drawings. In this embodiment, as one embodiment of the radiation noise suppressor, E
A description will be given of an example of the MI reduction VIA cap. FIG. 1 is a schematic view showing a state in which the EMI reducing VIA cap according to the present embodiment is mounted on a substrate, FIG. 4 is a perspective view showing the EMI reducing VIA cap, FIG. 5 is a ferrite bead mounted on a conductor, and FIG. Comparison diagram showing an equivalent model, FIG.
Is a ferrite bead and the EMI reducing VIA of the present invention.
FIG. 5 is a comparison diagram illustrating a principle of suppressing radiation noise of a cap. Note that, also in the present embodiment, description will be made using the conventional substrate 1 shown in FIG.

The EMI reduction VIA cap 21 according to the present embodiment is, as shown in FIGS.
And a support portion 23.

The shielding plate portion 22 is provided at the flange portion 6 of the power supply and signal VIA 6 where radiation noise is generated.
This is a member for covering only B small and suppressing radiation noise generated from the VIA 6. The shielding plate portion 22 is formed in a disk shape. This disk-shaped shielding plate portion 22
The size is set so as to cover the front and rear flange portions 6B of the IA6. The shielding plate 22 is made of a magnetic material such as a ferrite material or an insulator such as rubber containing the magnetic material.

The support section 23 is a member for supporting the shielding plate section 22 and fixing it to the substrate 1. This support portion 23
It is formed in a circular rod shape, and is integrally formed at the center of the shielding plate 22. The diameter of the support portion 23 is the cylindrical portion 6 of the VIA 6.
The dimensions are set to be substantially the same as the inner diameter of A. As a result, the support portion 23 is inserted into the VIA 6 to support and fix the shielding plate portion 22 to the substrate 1. Shield plate 22
Is supported in a state of covering the front and rear flange portions 6B of the VIA 6. This support portion 23 is
Similarly to 2, it is made of a magnetic material such as a ferrite material or an insulator such as rubber containing a magnetic material.

The shielding plate 22 has the following functions.

The impedance component Z of the ferrite material has the following relationship with the magnetic permeability μ _r and the frequency f.

[0024] _{Z = jωL = jωμ o μ r} K However, L: internal inductance component of the ferrite material ω: (= 2πf) f: Frequency μ _o: the permeability of vacuum ^{(4π × 10 -7 = 1.257 ×} 1
0 ⁻⁶ H / m) μ _r : permeability of the material K: constant depending on the size of the material As can be understood from this relational expression, the impedance component Z of the ferrite material is proportional to the permeability μ _r of the material. , Frequency f
The higher the value, the higher. For example, if a current containing low to high frequency components flows through a conductor,
If the impedance of the conductor in the high frequency band is high,
The high frequency component of the current becomes difficult to flow, and the current of the low frequency component passes. At this time, the current of the high frequency component is converted into heat.

Therefore, the EMI reduction VIA cap 21
Is attached to the VIA 6 on the substrate 1, the same function as the ferrite bead can be realized. Note that ferrite beads are EMI countermeasure components that reduce high-frequency components contained in a signal serving as a source of radiation noise by using the frequency characteristics of the impedance of a ferrite material (composite oxide of Fe and a metal).

FIG. 5 shows a generally known ferrite.
The principle of beads and an equivalent model are shown. The current flowing through the conductor through the ferrite bead creates a circumferential magnetic flux within the ferrite bead. This magnetic flux passes through the inside of the ferrite material, forms a large internal inductance in the conductor, and increases the impedance at high frequencies.

FIG. 6 shows a VIA cap 21 for reducing EMI.
Here is an example comparing the structure of ferrite beads with that of ferrite beads. E
The MI reduction VIA cap 21 is not a columnar ferrite material such as ferrite beads, but the substrate 1
Circular magnetic flux is generated in the shielding plate portion 22 located on the front surface and the back surface. As a result, a large internal inductance is formed in the VIA 6, and the impedance at high frequencies can be increased.

[Operation] The EMI reduction VIA cap 21 configured as described above operates as follows.

First, the EMI reduction VIA cap 21 is inserted into the cylindrical portion 6A of the VIA 6 for power supply of the substrate 1 from the front side and the back side. Specifically, the support portion 23 is inserted into the cylindrical portion 6A of the VIA 6, and the shield plate portion 22 is inserted.
Is pressed against the flange portion 6B of the VIA 6 to make it tightly adhere.
Thus, the support portion 23 is fixed to the cylindrical portion 6A of the VIA 6 with a fixed strength, and the shield plate portion 22 is supported in a state where the flange portion 6B of the VIA 6 is covered from both the front side and the rear side.

In this state, when the radiated noise is generated from the VIA 6, a circular magnetic flux is generated in the shielding plate portion 22, and the VIA 6
6, a large internal inductance is formed, and the impedance at high frequencies increases. Thereby, generation of high-frequency radiation noise is suppressed.

On the other hand, at the time of maintenance, the support portion 23 is held by holding the shielding plate portion 22 of the EMI reduction VIA cap 21.
From VIA6. With this alone, the members covering the elements and the like are removed, and there is no obstacle that hinders the maintenance work.

Further, since the shielding plate portion 22 of the EMI reduction VIA cap 21 only covers the flange portion 6B of the VIA 6 to a small extent, even if heat is generated, the heat is radiated to the surroundings. That is, even when the shielding plate portion 22 generates heat due to the radiation noise suppressing action, or when the element or the like generates heat, the heat is radiated to the surroundings.

[Effect] As described above, according to the present embodiment, the flange 6B of the VIA 6, which is the site where the radiation noise is generated, is covered by the shielding plate 22 of the EMI reduction VIA cap 21, so that the VIA 6 High-frequency radiated noise generated from the light source is suppressed.

At this time, the EMI reduction VIA cap 2
Since the first shield plate portion 22 only covers the flange portion 6B of the VIA 6 to a small extent, only a small space is required for suppressing radiation noise. For this reason, the EMI reduction VIA cap 21 can also be used for the substrate 1 having a high mounting density.

By simply inserting and removing the support portion 23 of the EMI reduction VIA cap 21 from the cylindrical portion 6A of the VIA 6,
Since the reduction VIA cap 21 can be easily attached to and detached from the substrate 1, the maintenance work can be made more efficient by removing the EMI reduction VIA cap 21 during maintenance.

Further, since the shielding plate portion 22 of the EMI reduction VIA cap 21 only covers the flange portion 6B of the VIA 6 to a small extent, the cooling efficiency is good, and
2 and the heat generated from the elements can be easily dissipated to the surroundings. As a result, heat does not accumulate on the substrate 1.

[Modifications] (1) In the above embodiment, the size of the EMI reduction VIA cap 21 is one, but VIs having different sizes are used.
If there is A6, EMs of different sizes
An I-reducing VIA cap 21 is used. In this case, the same operation and effect as the above embodiment can be obtained.

(2) In the above embodiment, the EMI reduction VIA cap 21 is used as the radiation noise suppressing tool.
Other forms of radiation noise suppressors may be used. In addition to the VIA 6, there is a site where radiated noise is generated, and by covering the surface of the site with a shielding plate, the same operation and effect as in the above embodiment can be achieved.

(3) In the above embodiment, the shielding plate 22
Although the support portion 23 is used as a means for fixing and supporting the device, other types of support portions may be used. For example, an adhesive member such as an adhesive or an adhesive tape may be used. In the case of an adhesive, it is interposed between the shielding plate portion 22 and the substrate 1 and both are joined and fixed.
In the case of an adhesive tape, the adhesive tape is attached to the substrate 1 so as to cover the shielding plate portion 22. At this time, an adhesive or an adhesive tape having an adhesive strength enough to be peeled off during maintenance is used.

[0040]

As described in detail above, the radiation noise suppressor according to the present invention has the following effects.

(1) The radiation noise suppressing device is made of a magnetic material or an insulator containing a magnetic material, and a shielding plate portion that covers only a portion where the radiation noise is generated and suppresses the radiation noise. The shield part is composed of a support part that fixedly supports the above part, and the support part fixedly supports the shield part at the part where radiation noise is generated. In addition, radiation noise can be suppressed easily and reliably.

(2) Since the shielding plate portion covers only a portion where the radiation noise is generated, the cooling efficiency is good, and the heat generated from the shielding plate portion and the elements can be easily radiated to the surroundings. . As a result, heat does not accumulate on the substrate or the like, and the reliability of the substrate or the like is greatly improved.

(3) Since the shielding plate portion covers only a portion where the radiated noise is generated, the space required for suppressing the radiated noise is small. Therefore, the radiation noise suppressor can be used for a substrate or the like having a high mounting density.

(4) Since the shield plate can be easily attached and detached by the support portion, the maintenance work can be made more efficient by removing the shield plate during maintenance.

(5) The radiation noise suppressor is replaced with an EMI reduction V.
Also in the case where the IA cap is used, the radiation noise can be easily and surely suppressed, and the heat generated in the element or the like can be reliably released. Further, in the case of the EMI reduction VIA cap, it can be easily attached or detached simply by inserting or removing the support portion into or from the through hole of the substrate, so that the maintainability is greatly improved.

(6) By forming the supporting portion of the shielding plate portion with an adhesive member that adheres to and supports a portion where radiation noise is generated, a portion where the shielding plate portion can be fixed, such as a through hole, is provided. The shield plate can be easily fixed even in a place where there is not.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a state in which an EMI reduction VIA cap according to an embodiment of the present invention is attached to a substrate.

FIG. 2 is a side sectional view showing a substrate according to a conventional technique.

FIG. 3 is a side sectional view showing a substrate on which conventional radiation noise suppression measures are taken.

FIG. 4 is a perspective view showing an EMI reduction VIA cap according to the embodiment of the present invention.

FIG. 5 shows a ferrite bead attached to a conductor,
FIG. 4 is a comparison diagram showing the equivalent model.

FIG. 6 is a comparison diagram showing the principle of suppressing radiation noise of ferrite beads and the EMI reduction VIA cap of the present invention.

[Explanation of symbols]

1: substrate, 2: signal wiring, 3: power supply layer, 4: ground layer,
5, 6: VIA (through hole), 6A: cylindrical portion, 6
B: flange portion, 7: impedance discontinuity point, 2
1: EMI reduction VIA cap, 22: shielding plate, 2
3: Support.

Continued on the front page (72) Inventor Takashi Watanabe 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. F-term (reference) 5E317 AA24 CD34 GG11 5E321 AA02 BB51 CC02 CC16 GG11 GH03

Claims (3)

[Claims] 1. A radiation noise suppressor for suppressing radiation noise generated at an impedance discontinuity, comprising a magnetic material or an insulator containing a magnetic material, and covering only a portion where radiation noise is generated. A radiation noise suppressor, comprising: a shielding plate portion for suppressing radiation noise through the support portion; and a support portion for fixing and supporting the shielding plate portion to the above-described portion. 2. The radiation noise suppressor according to claim 1, wherein the shielding plate portion covers only a through hole present on a substrate on which an IC or the like is mounted, and covers one or both of a front surface and a back surface thereof. EMI reduction VIA mounted on
The supporting portion is formed integrally with the EMI reducing VIA cap, and inserted into the through hole to form an E-cap.
A radiation noise suppressor comprising a support shaft for fixing and supporting a MI reduction VIA cap on the front surface or the back surface of a through hole. 3. The radiation noise suppressor according to claim 1, wherein the support portion is formed of an adhesive member that adheres and supports the shielding plate portion to a site where the radiation noise is generated. Radiation noise suppressor.