JPH11317585A - Electronic equipment and circuit board support device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an electronic equipment and a circuit support device, wherein resonance radiation is substantially prevented from occurring, a circuit grounding potential is kept stable, and furthermore radiation emitted from a circuit or the like can be blocked or restrained. SOLUTION: A circuit board 1 and an outer metal plate 2 are fixed together through the intermediary of a wall-like conductive spacer 3, which is brought into contact with the circuit board 1 and the outer metal plate 2 as long as prescribed in the peripheral direction of the circuit board 1. The spacers 3 are arranged confronting each other so as to support the circuit board 1 between them and the circuit board 1 is set detachably. Or a circuit board support device of rack structure which houses circuit boards can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device (electric device) in which a circuit board is fixed to an external metal surface such as a housing or a frame via a spacer, or an apparatus for supporting a circuit board by a spacer, particularly a circuit board. The present invention relates to an electronic device or a circuit board supporting device configured to prevent unnecessary electromagnetic wave noise from being generated.

[0002]

2. Description of the Related Art Conventionally, in various types of electronic equipment, as shown in FIG. 13, a circuit board 31 is formed by, for example, four pillars (pin-shaped) spacers 33 and screws 34 at four corners thereof. Metal surface 32 which is a structure itself such as a frame or a frame or a metal surface provided on the structure itself
However, in order to stabilize the ground potential in the circuit board 31, the spacer 33 is used as a metal spacer.
It is desirable to electrically connect the ground surface of the circuit board 31 and the external metal surface 32.

However, when the switching speed of signals used on the circuit board 31 is increased as in today, high-frequency noise generated on the circuit board 31 propagates to the external metal surface 32 via the spacer 33. , Spacer 3
A resonance current corresponding to the distance between the three flows, and a problem arises that large radiation noise is generated.

Accordingly, Japanese Patent Application Laid-Open No. 7-225634 describes
When the ground layer of the circuit board and the conductive body frame are electrically connected at a plurality of connection points, the ground layer is connected to the connection pad via a resistance member on the circuit board, so that the circuit board is connected to the body. A method for suppressing a noise current flowing into a frame is shown.

Japanese Unexamined Patent Application Publication No. 9-23083 discloses that when a signal ground of a circuit board and a housing forming a frame ground are electrically connected by a columnar metal spacer, a magnetic material is formed on the peripheral surface of the metal spacer. A method is disclosed in which a core is mounted or a resistance sheet is interposed between a metal spacer and a signal ground or a housing to suppress a noise current flowing from the circuit board into the housing.

[0006]

However, the conventional method disclosed in JP-A-7-225634 or JP-A-9-23083, on the other hand, uses a plurality of columnar spacers to connect a circuit board and an external metal surface. Since there is no difference in the connection, the generation of resonance radiation corresponding to the distance between the spacers cannot be essentially prevented, and, on the other hand, the resistance member or the magnetic core is used to stabilize the circuit ground potential. Since the current is suppressed, there is a disadvantage that new noise is generated due to instability of the circuit ground potential.

Accordingly, the present invention can substantially prevent the generation of resonance radiation, stabilize the circuit ground potential, and shield and suppress radiation from wiring and the like. Is made possible.

[0008]

In the first invention (the invention of claim 1), the circuit board and the external metal surface are connected to each other at a peripheral portion of the circuit board over a predetermined length in the peripheral direction. The circuit board and the external metal surface are fixed via a wall-shaped conductive spacer in contact with the external metal surface.

In this case, it is desirable that the spacer extends over 80% or more of the entire circumference of the circuit board.

It is preferable that the spacer electrically connects a ground surface of the circuit board to the external metal surface.

It is preferable that a power supply layer of the circuit board is disposed between the ground layer of the circuit board and the external metal surface.

Further, the cross-sectional shape of the spacer may be substantially U-shaped, and one flange may be brought into contact with the circuit board and the other flange may be brought into contact with the external metal surface.

Preferably, the spacer is elastically deformed and comes into contact with the circuit board and the external metal surface.

Further, a wiring connection portion can be attached to the spacer.

Further, a large number of minute holes can be provided in the spacer.

Further, the external metal surface may be a metal surface provided on another circuit board.

In the second invention (the tenth invention), a wall-shaped conductive spacer which can contact the circuit board over a predetermined length in the peripheral direction at the peripheral portion of the circuit board is provided.
The plurality of adjacent spacers are opposed to each other so as to support the circuit board.

In this case, the circuit board can be detachably attached to the adjacent spacer, and the adjacent spacers can be in contact with each other when the circuit board is not mounted.

The wall-shaped spacer can have a certain loss.

[0020]

According to the first aspect of the present invention having the above-described structure,
Rather than disposing the column spacers at intervals as in the conventional case, the wall spacers extending over a predetermined length in the peripheral direction of the circuit board are arranged. The generation of resonance radiation can be essentially prevented.

Further, instead of connecting the ground surface of the circuit board and the external metal surface via several columnar spacers as in the prior art, the wall-shaped spacer extends over a predetermined length in the peripheral direction of the circuit board. Since the ground surface of the circuit board and the external metal surface are connected via the interface, the impedance of the connection part can be greatly reduced compared to the conventional case, the circuit ground potential is stabilized, and the noise due to the instability of the circuit ground potential is reduced. Can be prevented, and the generation of radiation noise due to the impedance of the connection portion can be prevented.

According to the second aspect of the present invention, a circuit board supporting apparatus having a rack structure capable of attaching and detaching a circuit board or accommodating a plurality of circuit boards has the same effect as that of the first aspect. Obtainable.

[0023]

FIG. 1 shows an embodiment of an electronic apparatus according to the present invention.

In this embodiment, a wall-shaped conductive spacer 3 interposed between the circuit board 1 and the external metal surface 2 surrounds the entire periphery of the circuit board 1 as shown in FIG. Contact the circuit board 1 and the external metal surface 2 with
The circuit board 1 is fixed to the external metal surface 2 via the spacers 3 by screws 4 at four corners of the circuit board 1.

In this embodiment, as shown in FIG. 1B, the spacer 3 is formed of a metal as a leaf spring having a substantially U-shaped cross section, and the spacer 3 is formed of a circuit board 1. In a state where the two flange portions 3a and 3b of the spacer 3 are not fixed to the external metal surface 2, as shown in FIG. When the spacer 3 is fixed to the circuit board 1 and the external metal surface 2 by the screw 4, the flanges 3a and 3b are elastically deformed, respectively, so as to be parallel to each other.

Thus, the circuit board 1 can be stably fixed to the external metal surface 2 without increasing the number of screws 4, and the flanges 3a and 3b can be securely attached to the circuit board 1 and the external metal surface 2. And the circuit board 1 and the external metal surface 2 can be electrically connected reliably.

FIGS. 2A and 2B show an example of the internal structure of the circuit board 1 and a connection portion. In this example, a surface pad 5 having a predetermined width is formed around the lower surface of the circuit board 1 (a surface facing the external metal surface), and the surface pad 5 is
And via a via 6 ′ which also serves as a screw hole, is connected to the ground layer 7 in the circuit board 1 with low impedance over a frequency range from DC to high frequency. Then, by bringing the surface pad 5 into contact with the spacer 3, the ground layer 7 is electrically connected to the spacer 3 and further to the external metal surface with low impedance. The pitch of the via 6 is preferably as small as possible, preferably 5 cm or less, more preferably 2 cm or less.

The power supply layer 8 and the wiring 9 on the circuit board 1 where noise current is liable to be generated are located inside the ground layer 7, that is, the ground layer 7 in order to effectively use the radiation shielding effect described later of the present invention. It is desirable to arrange between the external metal surface.

The operation and effect of the electronic device of the present invention are as follows.
This is shown in comparison with a conventional electronic device. FIG.
(B) is a conventional electronic device shown in FIG.
634 or the conventional electronic device disclosed in Japanese Patent Application Laid-Open No. 9-23083, and (c) shows the electronic device according to the above-described embodiment of the present invention.

First, in the present invention, the columnar spacers 33 are not arranged at intervals as in the prior art, but the wall-shaped spacers 3 extending over a predetermined length in the peripheral direction of the circuit board 1 are arranged. Therefore, the resonance radiation (resonance current 12, radiation noise 1)
The occurrence of 3) can be essentially prevented. Hereinafter, this is referred to as a basic effect.

Next, in the present invention, instead of connecting the ground layer 11 of the circuit board 31 and the external metal surface 32 via several columnar spacers 33 as in the prior art, Since the ground layer 7 of the circuit board 1 and the external metal surface 2 are connected to each other via the wall-shaped spacer 3 having a length longer than a predetermined length, the impedance of the connection portion can be significantly reduced as compared with the related art. The ground potential is stabilized, so that generation of noise due to instability of the circuit ground potential can be prevented, and generation of radiation noise (18) due to the impedance (17) of the connection portion can be prevented. Hereinafter, this is referred to as a ground potential stabilizing effect.

Further, in the above-described embodiment of the present invention, since the space between the circuit board 1 and the external metal surface 2 is covered by the spacer 3 over the entire circumference of the circuit board 1, the circuit board 1
The ground layer 7, the spacer 3 and the external metal surface 2 form an almost completely sealed shield case, and radiated noise generated from the power supply layer and the wiring (14) located inside the shield case ( Current 15, radiation 16) can be shielded. Hereinafter, this is referred to as a radiation shielding effect.

The wall-shaped spacer 3 preferably extends over the entire circumference of the circuit board 1, but does not necessarily need to extend over the entire circumference of the circuit board 1. FIG. 4 shows an example in which the wall-shaped spacer does not extend all around the circuit board.

FIG. 3A shows a case where a wall-shaped spacer 3A is arranged only on one side of the circuit board 1 and columnar spacers 33 are arranged at both corners of the opposite side. 4) shows a case where one side of the circuit board 1 is an opening without a spacer and the wall-shaped spacer 3B is arranged over the other three sides. FIG.
C is arranged in a peripheral portion including each corner of the circuit board 1, and a part of each side of the circuit board 1 is used as an opening. FIG. In this case, the columnar spacers 33 are disposed at both corners of the frame, and the wall-shaped spacers 3D are disposed on the opposite side so as to surround the substrate on the side. However, a form in which these are combined or modified is also possible.

As in each example of FIG. 4, if the wall-shaped spacer is not provided over the entire circumference of the circuit board 1 and an opening exists in a part of the periphery of the circuit board 1, the above radiation shielding effect is reduced. However, the basic effect and the ground potential stabilizing effect are exhibited.

FIG. 5 shows the result of examining the influence of the opening. The ratio of the length of the non-opening, that is, the portion where the wall-shaped spacer is located, to the entire circumference of the A4-sized circuit board is shown. , And a change in radiation intensity with respect to the coverage is measured and plotted.

As apparent from FIG. 5, the coverage was 40%.
When the coverage is less than 40%, the radiation shielding effect cannot be expected. However, when the coverage is 40% or more, the radiation is reduced as the coverage is increased. When the rate is set to 80% or more, a radiation shielding effect equivalent to that in the case where the covering rate is set to 100% can be obtained by providing a wall-shaped spacer all around the substrate. However, in this measurement, the radiation shielding effect was mainly observed, and the coverage was 40%.
%, The other basic effects and the ground potential stabilizing effect are exhibited.

It is desirable that the entire wall spacer is made of a conductive material. However, holes or holes are formed in the wall portion 3c of the wall spacer as shown in FIG. An opening may be provided. In particular, when a large number of minute holes are provided in the wall surface portion 3c, sufficient ventilation can be ensured while preventing generation of new radiation and a decrease in the radiation shielding effect due to the holes.

Further, the effect of the present invention was confirmed by simulation. FIG. 6 shows the result,
5 is a calculation result by a moment method of a radiation spectrum when a microstrip line of 80 mm is formed on a circuit board of mm × 110 mm.

The dashed lines indicate the emission spectrum of a conventional electronic device in which the ground surface and the external metal surface of the circuit board are connected at four corners of the circuit board via columnar metal spacers.
The solid line is the radiation spectrum of the electronic device according to the embodiment of the present invention, in which the ground surface of the circuit board and the external metal surface are connected via the wall-shaped spacers all around the circuit board.

As is clear from FIG. 6, in the present invention,
The radiation intensity E greatly decreased in all frequency ranges, and the radiation peak around 700 MHz observed in the conventional device disappeared. The emission peak near 700 MHz is a resonance mode newly generated by a loop between the columnar spacers in the conventional device.
It has been confirmed that the generation of this new resonance radiation can be prevented. It is considered that the large radiation reduction in all frequency bands is due to the above-described ground potential stabilizing effect and radiation shielding effect of the present invention.

The cross-sectional shape of the wall-shaped spacer is not limited to a substantially U-shape as shown in FIG. 1, but is substantially a S (S) shape, a substantially I (eye) shape, a hollow or non-hollow circular shape, An elliptical shape, a hollow or solid square shape, etc. may be used.

FIG. 7 is a schematic sectional view of the wall-shaped spacer.
FIG. 3A shows a case where a ground surface is formed on the lower surface of the circuit board 1 (the surface facing the external metal surface 2), and FIG. 1 is a case where a ground surface is formed on the upper surface. (A)
(B) shows that each of the wall-shaped spacers 3 is a separate screw 4
In this case, the spacer 3 is fixed to the circuit board 1 and the external metal surface 2 by a common screw 4 as shown in FIG. Can also.

In the present invention, the ground surface (surface pad 5) of the circuit board 1 and the spacer 3 are usually directly connected as shown in FIG. And the wall-shaped spacer may be connected via an appropriate circuit element.

FIG. 8 shows an example of such a case. In this example, a surface ground pad 22 connected to an internal ground layer by a via 25 and a spacer pad 23 directly connected to a wall-shaped spacer are formed on the surface of the circuit board 1, and the surface ground pad 22 and the spacer pad are formed. And a circuit element 24 attached to the circuit board 1 so as to straddle both.
Connect through. As the circuit element 24, a resistance element,
An inductance, a capacitor, or the like can be used. When the impedance of the connection portion increases, the above-described ground potential stabilizing effect is suppressed, but other basic effects and radiation shielding effects are exhibited. The screw hole 26 is for inserting the screw 4 shown in FIG. 1 or the like.

The wall-shaped spacer is usually formed of a low-impedance metal, but the wall-shaped spacer may have a DC resistance loss of about several ohms or less. Also in this case, the ground potential stabilizing effect is suppressed by the increase in loss, but other basic effects and radiation shielding effects are exhibited.

As a method of connecting the circuit board to the outside,
The method as shown in FIG. 9, FIG. 10 or FIG. 11 can be adopted.

FIG. 9 shows a case where the receptacle 42 is attached to the upper surface of the circuit board 1, connected to the wiring on the circuit board 1, the plug 43 is attached to the receptacle 42, and the cable 44 is pulled out onto the external metal surface 2. FIG. 10 shows a state in which a receptacle 42 is attached to the lower surface of the circuit board 1 and connected to wiring on the circuit board 1, and a plug 43 is attached to the receptacle 42 inside the wall-shaped spacer 3, and a cable 44 is attached. Through the opening 45 formed in the spacer 3 onto the external metal surface 2.

FIGS. 11A and 11B show a state in which a receptacle 42 is attached to an opening formed in the wall-shaped spacer 3 and connected to a wiring on the circuit board 1 by an internal wiring 46. In this case, the plug 43 is attached to the receptacle 42.

In particular, the method of attaching the connector 41 to the spacer 3 as shown in FIG. 11 is as follows: (1) Since the distance between the cable 44 and the external metal surface 2 is short, mutual impedance is reduced, and generation of common mode noise is reduced. (2) The opening of the spacer 3 is closed by the connector 41, and the radiation shielding effect is excellent. (3) Since no connector is provided on the circuit board 1, the space on the circuit board 1 is effectively used. It can be used.

In each of the illustrated examples, the external metal surface 2 is larger than the circuit board 1. However, even if the circuit board and the external metal surface are the same size, the circuit board is larger than the external metal surface. However, the present invention can be applied.
When the circuit board is larger than the external metal surface, the wall-shaped spacer may be provided on the peripheral portion inside the outermost peripheral portion of the circuit board.

The external metal surface includes a metal surface (metal layer) provided on a structure of a metal plate or a metal body (metal layer) provided on a structure other than metal, and a metal surface (metal layer) provided on another circuit board. ). In the latter case, a plurality of circuit boards are stacked, and these circuit boards are connected via the wall-shaped spacer, and the above-described effects are realized for the plurality of connected circuit boards.

In the illustrated example, the circuit board 1 and the external metal surface 2 are fixed by screws 4 via a wall-shaped spacer 3. However, a fixing tool other than the screws, a conductive adhesive, or the like is used. May be fixed.

The present invention can also be applied to a circuit board supporting device having a rack structure in which a circuit board can be attached and detached or a plurality of circuit boards can be accommodated. Even in such a case, the above-described basic effect and ground potential stabilizing effect can be obtained. And a radiation shielding effect can be obtained. FIG. 12 shows an embodiment of this case.

In this embodiment, as shown in FIG. 1A, the circuit board 1 is provided with a surface pad 5 directly or indirectly connected to an internal ground layer over the entire periphery of both front and back surfaces.
2, a terminal 53 is provided on one side, and a panel 54 for forming a front cover of the device case or attaching a connector for connection to the outside is provided on the opposite side.

As shown in FIG. 1B, the wall-shaped spacer 3 is formed in a frame-like shape that comes into contact with the surface pads 52 over the entire circumference of the circuit board 1 and is also shown in FIG. Such elastic deformation portions (flanges) 3a and 3b are provided. However, in this case, since the spacer 3 is not fixed to the circuit board 1, a screw hole is unnecessary.

Then, as shown in FIG. 12C, a plurality of the spacers 3 are arranged at predetermined intervals, and the wall surface between the elastically deforming portions 3a and 3b is fixed to the device case 59. The sockets 5 into which the terminal portions 53 of the circuit board 1 are inserted are provided on the back board 58 of the device case 59.
7 so that signals can be transmitted through the backboard 58.

Circuit board 1 between two adjacent spacers
Is not inserted, one of the two spacers is configured such that the elastically deformable portion 3a on one side and the elastically deformable portion 3b on the other side are in contact with each other while being opened outward.

The circuit board 1 is placed between two adjacent spacers.
Is inserted, the elastic deformation portions 3a and 3b are elastically deformed inwardly by the inserted circuit board 1, and elastically contact the front and back surface pads 52 of the inserted circuit board 1. And the surface pad 52 and 2
Good electrical conductivity is obtained between the two spacers.

Circuit board 1 between two adjacent spacers
When no is inserted, a gap may be formed between the two spacers. However, if the two spacers are in contact with each other as described above so that no gap is formed between them, the radiation shielding There is an advantage that the effect is enhanced.

The elastically deformable portions 3a and 3b are formed by forming the spacers 3 as metal leaf springs as described above, and by forming the spacers 3 from conductive rubber or another elastic material having conductivity. You can also get.

According to this embodiment, since the ground surfaces of a plurality of circuit boards can be connected via the spacer 3, the circuit ground potential can be stabilized without generating new resonance radiation or the like. At the same time, radiation noise can be significantly reduced by the shielding effect of the spacer 3.

In the above example, the position of the spacer 3 is fixed, and the contact between the circuit board 1 and the spacer 3 is maintained by the elastic deformation of the elastic deformation portions 3a and 3b. After the circuit board 1 is inserted, the spacer 3 is pressed in one direction by an appropriate means for applying a mechanical pressure, so that the circuit board 1 is supported at a constant pressure. Contact may be maintained.

In this case, the pressure applying means is the device case 5
9 may be provided inside or outside. If necessary, the socket 57 can be configured to move on the backboard 58 as the circuit board 1 moves.

As described above, even when the contact between the circuit board 1 and the spacer 3 is maintained by the pressure applying means,
When the circuit board 1 is not inserted between the spacers, if the two spacers are in contact with each other, the radiation shielding effect of the circuit board non-housing portion is enhanced.

FIG. 12 shows an example in which the spacer 3 has a structure in which four sides are closed. For example, the spacer 3 may be formed into a shape having no side on the panel 54 side of the device case 59 and contact the panel 54. For example, the wall-shaped spacer may have an opening at one side or the like. In this case, the radiation shielding effect is somewhat reduced, but the other basic effects and the ground potential stabilizing effect are sufficiently exhibited.

[0067]

As described above, according to the present invention, the generation of resonance radiation can be essentially prevented, and the stabilization of the circuit ground potential can be realized.
Further, radiation from wiring and the like can be shielded and suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of an electronic device of the present invention.

FIG. 2 is a diagram illustrating an example of an internal structure and a connection portion of a circuit board.

FIG. 3 is a diagram showing an operation of the electronic device of the present invention in comparison with a conventional electronic device.

FIG. 4 is a diagram illustrating an example in which a wall-shaped spacer does not extend over the entire circumference of a circuit board.

FIG. 5 is a view showing a measurement result of a relationship between a spacer coverage and a radiation intensity in the electronic apparatus of the present invention.

FIG. 6 is a diagram showing the result of confirming the effect of the present invention by simulation.

FIG. 7 is a diagram showing an example in which the cross-sectional shape of the wall-like spacer is substantially S-shaped.

FIG. 8 is a diagram illustrating an example of a case where a ground surface of a circuit board and a wall-shaped spacer are connected via a circuit element.

FIG. 9 is a diagram illustrating an example of a method of connecting a circuit board to the outside.

FIG. 10 is a diagram showing another example of a method for connecting a circuit board to the outside.

FIG. 11 is a view showing still another example of a method of connecting a circuit board to the outside.

FIG. 12 is a view showing one embodiment of a circuit board support device of the present invention.

FIG. 13 is a diagram illustrating an example of a conventional electronic device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board 2 External metal surface 3 Spacer (wall-shaped spacer) 3a, 3b Elastic deformation part (flange part) 5 Surface pad 6 Via 7 Ground layer 8 Power supply layer 9 Wiring 41 Connector 44 Cable

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05K 9/00 H05K 9/00 G

Claims (11)

[Claims] 1. A wall-shaped conductive spacer in which a circuit board and an external metal surface are in contact with the circuit board and the external metal surface over a predetermined length in a peripheral direction at a peripheral portion of the circuit board. Via fixed electronics. 2. The electronic device according to claim 1, wherein the spacer extends over at least 80% of the entire circumference of the circuit board. 3. The electronic device according to claim 1, wherein the ground surface of the circuit board and the external metal surface are electrically connected by the spacer. 4. The electronic device according to claim 1, wherein: between a ground layer of the circuit board and the external metal surface.
An electronic device, wherein a power supply layer of the circuit board is arranged. 5. The electronic device according to claim 1, wherein said spacer has a substantially U-shaped cross section, one of said flanges being in contact with said circuit board, and the other being in contact with said external metal surface. Electronic equipment characterized by the following. 6. The electronic device according to claim 1, wherein the spacer is elastically deformed and is in contact with the circuit board and the external metal surface. 7. The electronic device according to claim 1, wherein a wiring connection portion is attached to the spacer. 8. The electronic device according to claim 1, wherein a number of minute holes are provided in said spacer. 9. The electronic device according to claim 1, wherein the external metal surface is a metal surface provided on another circuit board. 10. A plurality of wall-shaped conductive spacers capable of contacting the circuit board over a predetermined length in the peripheral direction at a peripheral portion of the circuit board, supporting the circuit board between a plurality of adjacent spacers. A circuit board support device placed opposite to obtain. 11. The circuit board supporting device according to claim 10, wherein said circuit board is detachably attached to said adjacent spacer, and said adjacent spacers are in contact with each other when said circuit board is not mounted. Characteristic circuit board support device.