JP4562666B2 - Electronic device with anti-static function - Google Patents

Description

  The present invention relates to an electronic device with an anti-static function, and more particularly to an anti-static structure of an electronic device that prevents malfunction and damage of an internal circuit of an active element that is mounted on a printed circuit board and connected to signal wiring by static electricity. .

  In the prior art, as an anti-static structure of an electronic device, a ground pin is disposed at a position closer to the opening of the exterior housing than the mounted electronic component and the signal wiring pattern of the electronic component mounting substrate. Discloses a technique in which a ground pattern is formed on the outer end facing the opening of the exterior housing, and a ground pin is connected and fixed to the ground pattern of the substrate (for example, see Patent Document 1).

JP 7-288367 A

  Patent Document 1: Japanese Patent Application Laid-Open No. 7-288367 discloses that a ground pin is provided on a mounted electronic component and a signal wiring pattern at a position close to an opening of an exterior housing. If one side of the outer casing is made of metal and a very strong electric field is applied to the metal part from the outside, the electric field intrudes into the casing from four sides where the outer casing is not metal. Not only is it necessary, but it is difficult to mount the ground pin when there are mounting parts such as connectors. In addition, when an induced current due to static electricity flows inside the housing, it is not effective to provide a ground pin near the entrance of the opening of the exterior housing.

  The present invention has been made to solve the above-described problems, and an attempt is made to obtain an electronic device with an anti-static function capable of accurately performing electrostatic protection by providing focused protection against static electricity for signal wiring. Is.

  An electronic device with an anti-static function according to the present invention includes a housing having a planar conductive portion at least in part and an electronic component mounted in parallel with the conductive portion of the housing inside the housing. A circuit board having a signal wiring layer and a ground potential layer provided, and an electrostatic protection wiring is disposed in parallel with the signal wiring of the signal wiring layer, and the electrostatic protection wiring is disposed on the electrostatic protection wiring. An antistatic member extending in a direction from the wiring to the conductive portion of the housing and disposed at a predetermined interval is provided, and the antistatic member is electrically connected to the ground potential layer. Is.

  According to the present invention, it is possible to obtain an electronic device with an anti-static function capable of accurately protecting the signal wiring by providing focused protection against static electricity.

Embodiment 1 FIG.
A first embodiment of the present invention will be described with reference to FIGS. 1 is a side view showing a cross section of an electronic device with an antistatic function according to Embodiment 1 of the present invention. 2 is a cross-sectional view taken along line II-II in FIG.

1 and 2, the housing 1 is composed of a metal housing member 1A that forms a conductive portion and a resin housing member 1B that forms an insulating portion, and the internal space of the housing 1 has a metal upper surface. It is covered with the housing member 1A, and the lower part and the side part are covered with the resin housing member 1B.
Inside the housing 1 is a printed circuit board 2, and the printed circuit board 2 includes a signal wiring layer 2A having a signal wiring pattern 2a, a ground layer 2B having a ground wiring pattern 2b, and the like. An electronic component including an active element 3 such as an IC is mounted on the printed circuit board 2, and the electronic component is connected to the ground part 5 and other electronic devices 6 through the connectors 4 through wiring patterns 2 a and 2 b. The wiring patterns include a signal wiring pattern 2 a and a ground wiring pattern 2 b, which are also arranged on the surface layer surface of the printed circuit board 2. Further, a guard wiring 2c is arranged in parallel with the signal wiring pattern 2a, and the avoidance electrostatic pins 7 are attached on the guard wiring 2c. The guard wiring 2c is connected to the ground wiring pattern 2b of the ground layer 2B through a through hole (not shown).
The electrostatic prevention pins 7 are arranged on the surface layer surface of the printed circuit board 2 and are provided on the guard wiring 2c so as to be perpendicular to the printed circuit board 2. A plurality of the electrostatic prevention pins 7 are provided at predetermined intervals. It is provided in the planted state.

  In such a configuration, when an electric field having a large amplitude and a high frequency, such as static electricity SE, is applied to the metal housing member 1A from the outside, even if the high-frequency current Ihf flows inside the metal housing member 1A, Electrostatic pins 7 → guard wiring in which the impedance is lower than the signal wiring pattern 2a disposed on the surface layer of the printed circuit board 2 from the inside of the metal housing member 1A, rather than passing through the signal wiring pattern 2a. The high-frequency current Ihf flows through the path 2c → the ground layer 2B → the connector 4 → the ground part 5, and no current flows through the active element 3 such as an IC.

  Thus, by providing the avoidance electrostatic pins 7 and the guard wiring 2c, the high-frequency current Ihf due to the electrostatic SE can be bypassed to the ground layer 2B of the printed circuit board 2, so that the active element 3 connected to the signal wiring pattern 2a It can prevent malfunction and damage of internal circuit.

According to Embodiment 1 of the present invention, a housing 1 having a metal housing member 1A as a planar conductive portion at least in part and a resin housing portion 1B as an insulating portion in another portion. And a signal wiring layer 2A and a ground layer 2B which are mounted in parallel with the metal casing member 1A as a planar conductive portion in the casing 1 on which an electronic component including an active element 3 such as an IC is mounted. A printed circuit board 2 having a ground potential layer, and an electrostatic protection wiring comprising guard wirings 2c on both sides thereof in parallel with the signal wiring 2a of the signal wiring layer 2A. An electrostatic protection wiring that is implanted and extends from the electrostatic protection wiring formed from the guard wiring 2c toward the metal housing member 1a as a conductive portion of the housing 1 extends to the electrostatic protective wiring formed from the guard wiring 2c. Predetermined A plurality of electrostatic protection members made up of electrostatic protection pins 7 arranged at intervals are provided, and the electrostatic protection members made up of the electrostatic protection pins 7 are connected to the ground wiring of the ground potential layer made up of the ground layer 2B. Since it is electrically connected to the pattern 2b, it is possible to obtain an electronic device with an anti-static function that can accurately protect the signal wiring 2a by providing focused protection against static electricity.
That is, there is a printed circuit board 2 whose upper surface is covered with a metal casing member 1A and whose lower and side portions are covered with a resin casing 1B. The printed circuit board 2 is composed of a signal layer 2A, a ground layer 2B, and the like. An active element 3 such as an IC is mounted on the printed circuit board 2, and an electronic component is connected to a ground part 5 or another electronic device 6 through a connector 4 through wiring patterns 2 a and 2 b, and a signal is transmitted to the wiring pattern. In a structure in which there are a wiring pattern 2a and a ground wiring pattern 2b, which are also provided on the surface layer surface of the printed circuit board 2, a guard wiring 2c is provided in parallel with the signal wiring pattern 2a, and the guard wiring 2c is avoided. The electrostatic pin 7 is attached, and the guard wiring 2c is connected to the ground wiring pattern 2b of the ground layer 2B through a through hole. In such a configuration, when an electric field having a large amplitude and a high frequency, such as static electricity SE, is applied to the metal casing member 1A from the outside, the metal casing is configured. Even if the high-frequency current Ihf flows inside the member 1A, it is not induced from the inside of the metal housing member 1A to the signal wiring pattern 2a disposed on the surface layer of the printed circuit board 2, but rather than passing through the signal wiring pattern 2a. The high-frequency current Ihf flows through the path of the avoidance electrostatic pins 7, the guard wiring 2 c, the ground layer 2 B, the connector 4, and the ground part 5, and no current flows through the active element 3.
Thus, by providing the avoidance electrostatic pins 7 and the guard wiring 2c, the high-frequency current Ihf due to static electricity can be bypassed to the ground layer 2B of the printed circuit board 2, so that the inside of the active element 3 connected to the signal wiring pattern 2a Circuit malfunction and damage can be prevented.

Embodiment 2. FIG.
A second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a side view showing a cross section of the electronic device with an antistatic function in the second embodiment.
In the second embodiment, the configuration other than the specific configuration described here has the same configuration contents as the configuration in the first embodiment described above, and exhibits the same operation. In the drawings, the same reference numerals indicate the same or corresponding parts.

In FIG. 3, a conductive rubber member RP is affixed to the inside of a metal casing member 1A that constitutes the casing 1, and a plurality of electrostatic protection devices that are implanted on the printed circuit board 2 and provided on the guard wiring 2c. Each pin 7 extends upward at the top and is joined to and electrically connected to the conductive rubber member RP.
In this way, by attaching the conductive rubber member RP to the inside of the metal housing member 1A and electrically connecting with the anti-static pins 7, an anti-static function can be performed.
In this way, the high frequency current Ihf can be bypassed in the order of the metal housing member 1A → the conductive rubber member RP → the electrostatic protection pin 7 → the guard wiring 2c → the ground layer 2B → the connector 4 → the ground part 5. The impedance can be made lower than the case where the avoidance electrostatic pins 7 are electrically insulated from the metal housing member 1A, and the high-frequency current Ihf can be made difficult to flow through the signal wiring pattern 2a.

According to the second embodiment of the present invention, in the configuration in the first embodiment, the metal casing member 1A extends in the extending direction of the metal casing member 1A as the conductive portion in the casing 1. Since the plate-like conductive rubber member RP is pasted and electrically connected to the avoiding electrostatic member made up of the avoiding electrostatic pins 7, the signal wiring is protected from static electricity by focusing on static electricity. It is possible to obtain an electronic device with an anti-static function that can be accurately performed and can further effectively protect against static electricity by reducing the impedance of the bypass path of the high-frequency current Ihf.
That is, the high-frequency current Ihf can be bypassed in the order of the metal housing member 1A → conductive rubber member RP → protective electrostatic pin 7 → guard wiring 2c → ground layer 2B → connector 4 → ground part 5 in order. The impedance can be made lower than when the pin 7 is electrically insulated from the metal housing member 1A, and the high-frequency current Ihf can be made difficult to flow through the signal wiring pattern 2a.

Embodiment 3 FIG.
A third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a side view showing a cross section of the electronic device with an antistatic function in the third embodiment.
In the third embodiment, the configuration other than the specific configuration described here has the same configuration contents as the configuration in the first embodiment or the second embodiment described above, and exhibits the same operation. It is. In the drawings, the same reference numerals indicate the same or corresponding parts.

As shown in FIG. 4, a plurality of evacuations are provided on the surface layer surface of the printed circuit board 2 and provided on the guard wiring 2c so as to be perpendicular to the printed circuit board 2 and provided at predetermined intervals. For the electric pins 7, in order to adjust the total length of the conductive rubber member RP, the electrostatic pins 7 and the guard wiring 2c, the interval between the adjacent electrostatic pins 7 is adjusted so as to satisfy the following expression (1). By doing so, it is possible to reduce the circulating current flowing between the conductive rubber member RP, the electrostatic prevention pin 7 and the guard wiring 2c, and the metal housing member 1A → the conductive rubber member RP → the electrostatic prevention pin 7 → the guard. The high-frequency current Ihf that flows in the order of the wiring 2c → the ground layer 2B → the connector 4 → the ground part 5 is made to flow easily.
[L1 (m) × √ (εr) + L1 (m) + L2 (m) × 2] <C (m / s) × 0.7 × 10 ⁻⁹ (s) Formula (1)
However, L1 is the distance (m) between adjacent electrostatic pins, L2 is the height (m) of the electrostatic pins, C is 3 × 10 ⁸ (m / s), 0.7 × 10 ⁻⁹ ( s) is the shortest rise time of static electricity shown in IEC61000-4-3, which is an international standard for static electricity. εr is the relative dielectric constant of the substrate of the printed circuit board.
By satisfying the condition of the above formula (1), the circulating current flowing between the conductive rubber member RP-the electrostatic protection pin 7-the guard wiring 2c has an electrical length of the above path of IEC61000-4-3. When the wavelength is longer than the wavelength corresponding to the shortest rise time shown (= C (m / s) × 0.7 × 10 ⁻⁹ (s)), the impedance of the above path decreases and the high-frequency current increases. To do.

According to the third embodiment of the present invention, in the configuration of the second embodiment, the interval L1 between the adjacent electrostatic avoidance members composed of the avoidance electrostatic pins 7 is adjusted so as to satisfy the above formula (1). As a result, it is possible to accurately protect the signal wiring 2a by providing focused protection against static electricity, and to protect the static electricity by reducing the circulating current at the portion of the electrostatic pins 7 including the conductive rubber member RP. In addition, it is possible to obtain an electronic device with an anti-static function that can be more effectively performed.
That is, with this configuration, it is possible to reduce the circulating current flowing between the conductive rubber member RP, the electrostatic prevention pin 7 and the guard wiring 2c, and the metal housing member 1A → conductive rubber RP → the electrostatic prevention pin 7 → The high-frequency current Ihf that flows in the order of the guard wiring 2c → the ground layer 2B → the connector 6 → the ground part 5 is made to flow easily.

Embodiment 4 FIG.
A fourth embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a side view showing a cross section of the electronic device with an antistatic function in the fourth embodiment. 6 is a cross-sectional view taken along line VI-VI in FIG.
In the fourth embodiment, the configuration other than the specific configuration described here has the same configuration contents as the configuration in the first embodiment described above, and exhibits the same operation. In the drawings, the same reference numerals indicate the same or corresponding parts.

  As shown in FIGS. 5 and 6, by connecting the top portion of the electrostatic prevention pin 7 with the conductive flat plates 8A and 8B, the metal housing member 1A → the conductive flat plates 8A and 8B → the electrostatic prevention pin 7 → the guard. The high-frequency current Ihf can be bypassed by a current path flowing in the order of the wiring 2c → the ground layer 2B → the connector 4 → the ground part 5, and the impedance is made smaller than that without the conductive flat plates 8A and 8B, so that the signal wiring pattern It is possible to make it difficult for the high-frequency current Ihf to flow through 2a.

According to the fourth embodiment of the present invention, in the configuration of the first embodiment, the top portions of the plurality of electrostatic protection members made of the electrostatic protection pins 7 are connected by the conductive flat plate members 8A and 8B. Therefore, it is possible to obtain an electronic device with an anti-static function capable of performing electrostatic protection precisely by reducing the impedance of the bypass path by performing focused protection against static electricity for the signal wiring 2a. .
That is, the high-frequency current Ihf can be bypassed by a current path that flows in the order of the metal housing member 1A → conductive plates 8A and 8B → avoidance electrostatic pins 7 → guard wiring 2c → ground layer 2B → connector 4 → ground part 5. In addition, the impedance can be made smaller than when the conductive flat plates 8A and 8B are not provided, so that the high-frequency current Ihf can hardly flow through the signal wiring pattern.

Embodiment 5 FIG.
A fifth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a side view showing a cross section of the electronic device with an antistatic function in the fifth embodiment.
In the fifth embodiment, the configuration other than the specific configuration described here has the same configuration content as the configuration in the first embodiment or the fourth embodiment described above, and exhibits the same operation. It is. In the drawings, the same reference numerals indicate the same or corresponding parts.

As shown in FIG. 7, the conductive circuit board 2 is provided on the surface of the printed circuit board 2 so as to be perpendicular to the printed circuit board 2 on the guard wiring 2c, and is provided at a predetermined distance from each other. In order to adjust the total length of the conductive flat plates 8A, 8B, the avoiding electrostatic pins 7 and the guard wiring 2c, the following formula (2) is satisfied for the plurality of avoiding electrostatic pins 7 provided with 8A and 8B. By adjusting the distance between the avoiding electrostatic pins 7, the circulating current flowing between the conductive flat plates 8A and 8B-the avoiding electrostatic pins 7 and the guard wiring 2c can be reduced. The high-frequency current Ihf that flows in the order of the flat plates 8A and 8B → the electrostatic prevention pins 7 → the guard wiring 2c → the ground layer 2B → the connector 4 → the ground portion 5 is made to flow easily.
[L3 (m) × √ (εr) + L3 (m) + L4 (m) × 2] <C (m / s) × 0.7 × 10 ⁻⁹ (s) Equation (2)
However, L3 is the distance (m) between adjacent electrostatic pins having conductive plates 8A and 8B provided on the top, and L4 is the height of the electrostatic pins having conductive plates 8A and 8B provided on the top. (m), C is the speed of light, 3 × 10 ⁸ (m / s), and 0.7 × 10 ⁻⁹ (s) is the shortest rise time of static electricity shown in IEC61000-4-3, which is an international standard for static electricity. εr is the relative dielectric constant of the substrate of the printed circuit board.
By satisfying the condition of the above formula (2), the electrical length of the above-mentioned path of the circulating current flowing between the conductive plates 8A and 8B-the electrostatic pins 7-the guard wiring 2c is IEC61000-4-3. When the wavelength is longer than the wavelength corresponding to the shortest rise time of static electricity (= C (m / s) × 0.7 × 10 ⁻⁹ (s)) shown in FIG. Increase.

According to the fifth embodiment of the present invention, in the configuration in the fourth embodiment, the interval between the electrostatic avoidance members composed of the electrostatic avoidance pins 7 is adjusted so as to satisfy the above formula (2). The signal wiring 2a can be properly protected by providing focused protection against static electricity, and more effectively can be protected by reducing the circulating current in the portion of the electrostatic pins 7 including the conductive plates 8A and 8B. An electronic device with an anti-static function that can be obtained can be obtained.
That is, the circulating current flowing between the conductive flat plates 8A and 8B-the electrostatic prevention pins 7 and the guard wiring 2c can be reduced, and the metal casing member 1A → conductive flat plates 8A and 8B → the electrostatic prevention pins 7 → guard. The high-frequency current Ihf that flows in the order of the wiring 2c → the ground layer 2B → the connector 4 → the ground part 5 is made to flow easily.

Embodiment 6 FIG.
A sixth embodiment of the present invention will be described with reference to FIG. FIG. 8 is a top view showing a cross section of the electronic device with an antistatic function in the sixth embodiment.
In the sixth embodiment, the configuration other than the specific configuration described here has the same configuration contents as the configurations in the first embodiment, the fourth embodiment, and the fifth embodiment described above. However, it has the same effect. In the drawings, the same reference numerals indicate the same or corresponding parts.

  As shown in FIG. 8, it is arranged on the surface layer surface of the printed circuit board 2 and is provided perpendicularly to the printed circuit board 2 on the guard wiring 2c, and is provided in a planted state with a predetermined distance from each other. For the plurality of electrostatic pins 7 provided with the conductive plate 8 on the side, the conductive plate 8 is expanded so as to cover the signal wiring pattern 2a, thereby allowing signal wiring from the inside of the metal housing member 1A. The high frequency current Ihf is less likely to be induced in the pattern 2a.

According to Embodiment 6 of the present invention, in the configuration of Embodiment 5, the conductive flat plate member 8 covers the signal wiring pattern 2a, and the conductive flat plate member 8 is connected to the signal wiring pattern 2a and the signal wiring pattern 2a. Since the metal housing member 1A is interposed between the metal housing member 1A and the metal housing member 1A, the signal wiring 2a is provided with an anti-static function capable of accurately protecting the signal wiring 2a by focusing on static electricity. A device can be obtained.
That is, by expanding the conductive flat plate member 8 to cover the signal wiring pattern 2a, the high-frequency current Ihf is less likely to be induced in the signal wiring pattern 2a from the inside of the metal housing member 1A.

  In the above-described embodiment, the avoidance electrostatic pin 7 has been described as having a pin shape, but can be formed as an avoidance electrostatic member having a shape other than the pin shape.

BRIEF DESCRIPTION OF THE DRAWINGS It is a side view which shows the cross section of the electronic device with an electrostatic resistant function in Embodiment 1 by this invention. It is sectional drawing in the II-II line of FIG. It is a side view which shows the electronic device with an electrostatic resistant function in Embodiment 2 by this invention in a cross section. It is a side view which shows in cross section the electronic device with an antistatic function in Embodiment 3 by this invention. It is a side view which shows in cross section the electronic device with an electrostatic resistance function in Embodiment 4 by this invention. It is sectional drawing in the VI-VI line of FIG. It is a side view which shows in cross section the electronic device with an electrostatic resistance function in Embodiment 5 by this invention. It is a top view which shows the electronic device with an electrostatic resistant function in Embodiment 6 by this invention in a cross section.

Explanation of symbols

1 casing, 1A metal casing member, 1B resin casing member, RP conductive rubber member, 2 printed circuit board, 2A signal wiring layer, 2a signal wiring pattern, 2B ground layer, 2b ground wiring pattern, 2c guard wiring, 3 Active elements such as ICs, 4 connectors, 5 ground parts, 6 other electronic devices, 7 electrostatic pins, 8, 8A, 8B conductive plate members.

Claims (3)

A housing having at least a part of a planar conductive portion, and a signal wiring layer and a ground potential layer that are mounted in parallel with the conductive portion of the housing in which the electronic component is mounted A circuit board, and an electrostatic protection wiring is disposed in parallel with the signal wiring of the signal wiring layer, and the electrostatic protection wiring is directed from the electrostatic protection wiring to the conductive portion of the housing. An anti-static member extending in a direction and disposed at a predetermined interval, electrically connecting the anti-electrostatic member to the ground potential layer, and inside the conductive portion of the housing The conductive rubber member is disposed and electrically connected to the electrostatic protection member, L1 is the interval (m) of the electrostatic protection member, L2 is the height (m) of the electrostatic prevention member, C is 3 × 10 ⁸ at the speed of light ^{(m / s), 0.7 ×} 10 -9 (s) stands on the electrostatic shown in IEC61000-4-3 international standard static [L1 (m) × √ (εr) + L1 (m) + L2 (m) × 2] <C (m / s) × where εr is the relative dielectric constant of the substrate of the circuit board An electronic device with an antistatic function, wherein the interval L1 of the electrostatic protection member is adjusted so as to satisfy 0.7 × 10 ⁻⁹ (s). A housing having at least a part of a planar conductive portion, and a signal wiring layer and a ground potential layer that are mounted in parallel with the conductive portion of the housing in which the electronic component is mounted A circuit board, and an electrostatic protection wiring is disposed in parallel with the signal wiring of the signal wiring layer, and the electrostatic protection wiring is directed from the electrostatic protection wiring to the conductive portion of the housing. An anti-static member extending in a direction and disposed at a predetermined interval, electrically connecting the anti-electrostatic member to the ground potential layer, and electrically conducting a top portion of the anti-static member. L3 is the distance (m) between adjacent electrostatic protection members provided with a conductive flat plate member at the top, and L4 is an electrostatic discharge protection device provided with a conductive flat plate member at the top. Member height (m), C is the speed of light, 3 × 10 ⁸ (m / s), 0.7 × 10 ⁻⁹ (s) is the international standard for static electricity, IEC61 When εr is the relative dielectric constant of the circuit board base, [L3 (m) × √ (εr) + L3 (m) + L4 (m) × 2] An electronic device with an anti-static function, wherein the interval L3 between the electrostatic protection members is adjusted so as to satisfy <C (m / s) × 0.7 × 10 ⁻⁹ (s). The electronic device with antistatic function according to claim 2, wherein the signal wiring is covered with the conductive flat plate member.

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