JP2008226966A - Grounding structure of printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the grounding structure of a printed wiring board which facilitates study on the appropriateness of grounding of the printed wiring board with regard to problems of electromagnetic interference (EMI) and electrostatic discharge (ESD), and allows mass production of the printed wiring board having the structure just subjected to study on the appropriateness of grounding. <P>SOLUTION: In the grounding structure, the middle of a sheet metal piece 30 for grounding is bent inwardly to form a support leg 30a. A front end side half piece 30b of the sheet metal piece 30 is set afloat on a ground pattern exposed portion 2, while a base end side half piece 30c of the sheet metal piece 30 is set afloat on the surface of an insulating sheathing of a printed wiring board 1. From either of screw insertion holes 30e and 30f formed on the front end side half piece 30b and the base end side half piece 30c of the sheet metal piece 30, a screw 4 is screwed through either of screw insertion holes 1e and 1f of the printed wiring board 2 into either of screw holes 5e and 5f on the rear-side support 5. The screw 4 is grounded when screwed in from the screw insertion hole 30e on the front end side half piece 30b, and is not grounded when screwed in from the screw insertion hole 30f on the base end side half piece 30c. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a grounding structure of a printed wiring board built in an electronic device, and more particularly, an improved printed wiring board that can be mass-produced with a structure as it is, which examines whether grounding is appropriate by switching between a grounded state and a non-grounded state Relates to the grounding structure.

  In projectors and other electronic devices with a built-in printed wiring board, in order to deal with electromagnetic interference (EMI) problems and electrostatic discharge (ESD) problems, there are cases where the appropriateness of grounding of the printed wiring board is examined.

  However, until now, after examining the suitability of grounding, the printed wiring board and the sheet metal for grounding etc. have been changed to cope with it, so the efficiency is poor, and it is necessary to reconfirm whether it is acceptable after the change. Therefore, there was a problem that the development schedule was prolonged and the cost was increased.

  On the other hand, as a technology for switching the printed circuit board between the grounded state and the non-grounded state, a printed circuit board having a ground pattern is fixed to the chassis with a screw, and the ground pattern and the chassis are connected via this screw to take the ground. A device is known in which the size of the head of a screw or the ground state is changed by a washer interposed between the head of the screw and a printed board (Patent Document 1).

  Also, a land with a hole is formed at the input part of the electronic circuit unit of the printed circuit board, a metal frame connected to the ground is provided on the rear surface of the land, and an electronic circuit is determined depending on whether screws are screwed into the metal frame from the hole in the land. There is also known a printed circuit device capable of changing the setting of the operation specifications of the unit (Patent Document 2).

The electronic device includes a circuit board, a housing, and a spacer between them, and the spacer is interposed between the conductive portion of the circuit board and the conductive portion of the housing as either a conductive medium or an insulating medium. An electronic device is also known (Patent Document 3).
JP-A-6-350269 Japanese Patent Laid-Open No. 9-270589 JP 2003-218558 A

  However, the electronic device disclosed in Patent Document 1 selects two types of screws having different head sizes to switch between a grounded state and a non-grounded state, or switches between a grounded state and a non-grounded state depending on the presence or absence of a washer. Therefore, it is necessary to prepare two types of screws and washers, which increases the number of parts.

  In addition, since the printed circuit device disclosed in Patent Document 2 connects an input portion of an electronic circuit unit and a metal frame behind the screw via a screw, a conductive screw is required and connection is not necessary. Has a problem that the printed circuit board cannot be fixed to the metal frame at the input portion of the electronic circuit unit.

  And since the electronic device of the said patent document 3 needs to prepare the spacer used as a conduction | electrical_connection medium and the spacer used as an insulation medium, there also exists a problem that a number of parts also increases.

  As described above, there are various means for switching the printed wiring board between the grounded state and the non-grounded state, but each has advantages and disadvantages, and room for improvement remains.

  The present invention has been made under the above circumstances, and it is possible to easily examine the suitability of grounding of a printed wiring board against problems of electromagnetic interference (EMI) and electrostatic discharge (ESD). It is another object of the present invention to provide a grounding structure for a printed wiring board that can be used for mass production with the same structure that has been examined for the appropriateness of grounding.

  In order to solve the above problems, a grounding structure of a printed wiring board according to the present invention is arranged in a state where a grounding sheet metal piece is floated above an exposed portion of the ground pattern of the printed wiring board, and a screw insertion hole is formed in the sheet metal piece. The screw insertion hole is formed in the printed wiring board and the screw hole is formed in the support on the back side of the printed wiring board so that the screw insertion hole is positioned directly below the screw insertion hole, and the screw is inserted from the screw insertion hole of the sheet metal piece. The sheet metal piece is brought into contact with the exposed portion of the ground pattern by being screwed into the screw hole of the support through the screw insertion hole of the printed wiring board.

  In the grounding structure of the printed wiring board according to the present invention, it is preferable to form a support leg portion that abuts the insulating coating surface of the printed wiring board by bending the tip of the grounding sheet metal piece.

  In addition, the middle part of the sheet metal piece for grounding is bent to form a supporting leg part that contacts the insulating coating surface of the printed wiring board, and the half piece on the tip side from the supporting leg part of the sheet metal piece is located above the exposed part of the ground pattern. Placed in a state where it floats on the top and the half piece on the base end side from the support leg part of the sheet metal piece is placed above the insulating coating surface of the printed wiring board, and placed on the tip half piece and the base end side half piece of the sheet metal piece. Form screw insertion holes, and form two screw insertion holes on the printed wiring board and two screw holes on the back side of the printed wiring board so that they are located directly below these screw insertion holes, It is preferable that a screw is screwed into one of the screw holes of the support through one of the screw insertion holes of the printed wiring board from one of the screw insertion holes of either the front end side half piece or the base end side half piece. . Furthermore, it is also preferable to form a screw insertion hole close to the base end portion of the sheet metal piece in the half piece on the base end side of the sheet metal piece.

  A more specific preferred printed wiring board grounding structure according to the present invention is formed by bending a middle portion of a grounding sheet metal piece to form a support leg that contacts the insulating coating surface of the printed wiring board. Arranged in a state where the half on the tip side of the support leg part is floated above the exposed part of the ground pattern, and the half on the base end side from the support part of the sheet metal piece is floated above the insulating coating surface of the printed circuit board The screw insertion hole is formed in the front half of the sheet metal piece close to the tip of the sheet metal piece, while the screw insertion hole is formed in the base half of the sheet metal piece close to the base end of the sheet metal piece. Two screw insertion holes are formed on the printed circuit board so that they are located directly below the screw insertion holes, and two screw holes are formed on the support on the back side of the printed circuit board. One of the side halves It is characterized in that it has from the insertion hole so screwed to one of the threaded holes of the support through one of the screw insertion hole of the printed wiring board screws.

  According to the grounding structure of the printed wiring board of the present invention, when a screw is screwed from the screw insertion hole of the sheet metal piece into the screw hole of the support through the screw insertion hole of the printed wiring board, the sheet metal piece is the exposed portion of the ground pattern at the head of the screw. Since it is pressed against and touches, it is in a grounded state. On the other hand, when the screw is not screwed in, the sheet metal piece floats above the ground pattern exposed portion of the printed circuit board and does not come into contact with the ground pattern exposed portion. Thus, according to the grounding structure of the printed wiring board of the present invention, the suitability of grounding can be examined by switching the printed wiring board between a grounded state and a non-grounded state depending on whether a screw is screwed. In addition, since the screw presses the sheet metal piece against the exposed portion of the ground pattern at its head, a non-conductive resin screw can also be used.

  In the grounding structure described above, if a slight load acts on the sheet metal piece in a non-grounded state, the sheet metal piece may come into contact with the ground pattern exposed portion of the printed wiring board to be in a grounded state. In the grounding structure in which the tip end portion of the sheet metal piece for grounding is bent to form a support leg portion that contacts the insulating coating surface of the printed wiring board, the tip end portion of the sheet metal piece is supported by the support leg portion, A clearance of at least the height of the support leg is ensured between the printed circuit board ground pattern exposed part and the sheet metal piece is subjected to some load unless it is pressed against the ground pattern exposed part with a screw. Even if it is received, it does not come into contact with the exposed portion of the ground pattern, and the ungrounded state can be reliably maintained.

  Further, as described above, the middle part of the sheet metal piece for grounding is bent to form a support leg part that comes into contact with the insulating coating surface of the printed wiring board, and the half piece on the tip side from the support leg part of the sheet metal piece is made of the ground pattern. Arrange it in a state of floating above the exposed part, and arrange the half piece on the base end side from the support leg part of the sheet metal piece in a state of floating above the insulating coating surface of the printed wiring board. Screw insertion holes are formed in the end half, and the two screw insertion holes are formed on the printed wiring board and the two screw holes are formed on the support on the back side of the printed wiring board so as to be positioned directly below these screw insertion holes. What is formed is that when the screw is screwed into one screw hole of the support through one screw insertion hole of the printed wiring board from the screw insertion hole of the tip half of the sheet metal piece, the tip half of the sheet metal piece becomes the head of the screw. Printed circuit board The ground state to contact pressed against the command pattern exposure unit. Then, when the screw is screwed into the other screw hole of the support through the other screw insertion hole of the printed wiring board from the screw insertion hole of the proximal half of the sheet metal piece, the proximal half of the sheet metal piece is the head of the screw. When pressed against the insulating coating surface of the printed wiring board, the tip half of the sheet metal piece rotates upward with the fulcrum as a fulcrum and tilts obliquely upward with the reaction, and the tip half and the exposed portion of the ground pattern A large clearance is ensured between them, and a non-grounding state is established. This grounding structure can easily and reliably switch between the grounded state and the non-grounded state depending on whether the screw is inserted from the screw insertion hole of the front end side half piece or the base end side half piece of the sheet metal piece as described above. Even in this case, the printed wiring board can be attached and fixed to the support body together with the sheet metal piece with screws, so switching between the grounded state and the non-grounded state to determine whether it is suitable for grounding, then the sheet metal piece It is possible to enter mass production as it is without any change or reconfirmation after the change. Therefore, the development schedule can be shortened, and the cost can be reduced.

  Then, as in a more preferable grounding structure, when the screw insertion hole is formed close to the tip end portion of the sheet metal piece in the tip half of the sheet metal piece, when the screw is screwed from the screw insertion hole, the support leg and the tip side half piece are deformed. Therefore, even if the screw is removed, there is no risk that the tip half will come into contact with the exposed portion of the ground pattern, and the screw insertion hole is formed close to the base end of the sheet metal piece. The thing has an advantage which can prevent that a front end side half piece tilts too much when a screw is screwed in from this screw insertion hole.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an exploded sectional view showing a grounding structure of a printed wiring board according to a basic embodiment of the present invention, and FIG. 2 is a sectional view of the grounding structure.

  1 and 2, reference numeral 1 denotes a printed wiring board built in an electronic device. A ground pattern is formed on the printed wiring board 1, and an exposed portion 2 of the ground pattern is a printed wiring board 1. Is formed around a screw insertion hole 1a drilled in the end of the screw.

  Above the ground pattern exposed portion 1a of the printed wiring board 1, a sheet metal piece 3 for grounding is arranged in a state of being lifted with an appropriate clearance, and the front end of the sheet metal piece 3 is bent into a V shape. Thus, a supporting leg portion 3 a that abuts against the insulating coating surface of the printed wiring board 1 is formed. The sheet metal base 3b bent downward from the sheet metal piece 3 is attached to a metal frame (not shown), a grounded shield plate (not shown) or the like of the electronic device.

  A screw insertion hole 3c through which the screw 4 is inserted from above is formed at substantially the center of the sheet metal piece 3. The screw insertion hole 1a is located directly below the screw insertion hole 3c. It is formed in the edge part. A screw hole 5a into which the screw 4 is screwed is formed in the support 5 on the back surface side of the printed wiring board 1 so as to be located immediately below the screw insertion holes 3c and 1a.

  As shown in FIG. 2, when the screw 4 is screwed from the screw insertion hole 3c of the sheet metal piece 3 into the screw hole 5a of the support 5 through the screw insertion hole 1a of the printed wiring board 1, as shown in FIG. The piece 3 is pressed against the ground pattern exposed portion 2 of the printed wiring board 1 by the head 4a of the screw 4 and comes into contact with the ground pattern, and the printed wiring board 1 is attached and fixed to the support 5 with the screw 4. .

  On the other hand, when the screw 4 is not screwed in, the sheet metal piece 3 floats above the ground pattern exposed portion 2 of the printed wiring board 1 and does not contact the exposed portion 2 as shown in FIG. Become. In this case, the tip end portion of the sheet metal piece 3 is supported by the support leg portion 3a, and at least the clearance corresponding to the height of the support leg portion 3a is secured between the sheet metal piece 3 and the ground pattern exposed portion 2 of the printed wiring board 1. The sheet metal piece 3 does not come into contact with the ground pattern exposed portion 2 even under a slight load, and can reliably maintain a non-grounded state.

  As described above, the grounding structure of the printed wiring board shown in FIGS. 1 and 2 switches the printed wiring board 1 between a grounded state and a non-grounded state depending on whether or not the screw 4 is screwed in, so that the suitability of grounding is simple and reliable. In addition, since the screw 4 may be any one that presses the sheet metal piece 3 against the ground pattern exposed portion 2 with the head 4a, the non-conductive resin screw or the like is also used. be able to.

  3 is an exploded sectional view showing a ground structure of a printed wiring board according to another embodiment of the present invention, FIG. 4 is a sectional view of the ground structure in the ground state, and FIG. 5 is a sectional view of the ground structure in a non-ground state. It is.

  In this printed wiring board grounding structure, an intermediate portion of the grounding sheet metal piece 30 is bent into a V shape to form a support leg 30a that contacts the insulating coating surface of the printed wiring board 1. The half piece 30b on the tip side from the support leg portion 30a of the 30 is arranged in a state of floating above the ground pattern exposed portion 2 of the printed wiring board 1. And the half piece 30c of the base end side from the support leg part 30a of the sheet metal piece 30 is arrange | positioned in the state which floated above the insulating coating surface of the edge part of the printed wiring board 1, and also bend | folds downward from this sheet metal piece 30 The sheet metal base 30d is attached to a metal frame (not shown) of an electronic device.

  Screw insertion holes 30e and 30f through which screws 4 are inserted from above are formed in the front end side half piece 30b and the base end side half piece 30c of the sheet metal piece 30, respectively. Are formed with two screw insertion holes 1e, 1f and two screw holes 5e, 5f, respectively, so as to be located directly below the screw insertion holes 30e, 30f. However, the screw 4 can be screwed in. The ground pattern exposed portion 2 is provided around a screw insertion hole 1e formed in the printed wiring board 1 so as to be positioned directly below the screw insertion hole 30e of the tip half 30b.

  In this printed wiring board grounding structure, as shown in FIG. 4, the screw 4 is passed through one screw insertion hole 1 e of the printed wiring board 1 from the screw insertion hole 30 e of the front end side half 30 b of the sheet metal piece 30. When screwed into the screw hole 5e, the front end side half 30b of the sheet metal piece 30 is pressed against and contacted with the ground pattern exposed portion 2 of the printed wiring board 1 by the head 4a of the screw 4. Then, as shown in FIG. 5, the screw 4 is screwed into the other screw hole 5 f of the support 5 through the other screw insertion hole 1 f of the printed wiring board 1 from the screw insertion hole 30 f of the proximal half 30 c of the sheet metal piece 30. Then, the proximal half 30c of the sheet metal piece is pressed against the insulating coating surface of the printed wiring board 1 by the head 4a of the screw 4, and the reaction piece causes the distal half 30b of the sheet metal piece to face upward with the support leg 30a as a fulcrum. By rotating and tilting obliquely upward, a large clearance is ensured between the front end side half piece 30e and the ground pattern exposed portion 2, and a non-grounding state is obtained.

  As described above, the grounding structure of the printed wiring board is configured to be grounded or non-grounded depending on which of the screw insertion hole 30e or 30f of the front end side half piece 30b or the base end side half piece 30c of the sheet metal piece 30 is screwed. The state can be switched easily and reliably, and in either case of grounding or non-grounding, the printed wiring board 1 can be attached and fixed to the support body 5 together with the sheet metal piece 30 with the screw 4, so that the grounding state and the non-grounding state If you decide whether or not to determine the appropriateness of grounding after that, you can go into mass production without changing the sheet metal piece 30, the printed wiring board 1, etc. or re-checking after the change It becomes possible. Therefore, if this printed circuit board grounding structure is adopted, the development schedule can be shortened and the cost can be reduced.

  3 to 5, screw insertion holes 30e and 30f are formed at substantially the center of the front end half 30b and the base end half 30c of the sheet metal piece 30, respectively. However, the screw insertion hole 30e of the distal end side half 30b is formed close to the distal end of the sheet metal piece so that the screw insertion holes 30e, 30f are far from the support leg 30a, and the screw insertion hole 30f of the proximal end half piece 30c is formed. The screw insertion holes 1e, 1f of the printed circuit board 1 and the screw holes 5e, 5f of the support body 5 are formed so as to be positioned close to the base end portion of the sheet metal piece and directly below these screw insertion holes 30e, 30f. It is desirable to form.

  If the positions of the screw insertion holes 30e and 30f are changed as described above, the deformation of the support leg 30a and the front end side half piece 30b is small when the screw 4 is screwed from the screw insertion hole 30e of the front end side half piece 30b of the sheet metal piece 30. Therefore, even if the screw 4 is pulled out, there is no fear that the tip side half piece 30b contacts the ground pattern exposed portion 2, and when the screw 4 is screwed from the screw insertion hole 4 of the base side half piece 30c of the sheet metal piece 30. The tip half 30b can be prevented from being excessively inclined.

It is an exploded sectional view showing the grounding structure of the printed wiring board concerning one basic embodiment of the present invention. It is sectional drawing of the grounding structure. It is an exploded sectional view showing the ground structure of the printed wiring board concerning other embodiments of the present invention. It is sectional drawing of the grounding state of the grounding structure. It is sectional drawing of the non-grounding state of the grounding structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printed wiring board 1a, 1e, 1f Screw penetration hole 2 Exposed part of ground pattern 3,30 Sheet metal piece 3a, 30a Grounding part 3c, 30e, 30f Screw insertion hole 30b Tip side half 30c Base side half 4 Screw 4a Screw head 5 Support 5a, 5e, 5f Screw hole

Claims (5)

  The middle part of the sheet metal piece for grounding is bent to form a support leg that contacts the insulating coating surface of the printed wiring board, and the half on the tip side of the support part of the sheet metal piece is floated above the exposed part of the ground pattern. In addition, the base half of the metal plate is positioned above the insulating coating surface of the printed wiring board, and the screw insertion hole is formed in the front half of the metal plate. On the other hand, a screw insertion hole is formed in the base half of the sheet metal piece close to the base end of the sheet metal piece, and two screw insertion holes are printed so as to be located directly below these screw insertion holes. Two screw holes are formed in the wiring board on the support on the back side of the printed wiring board, and the screw is inserted into the printed wiring board from the screw insertion hole of either the front half or the base half of the sheet metal piece. Through one of the screw insertion holes Grounding structure of a printed wiring board, characterized in that as screwed into one of the threaded holes of the support.   Place the sheet metal piece for grounding in a state of floating above the exposed part of the ground pattern of the printed wiring board, form a screw insertion hole in the sheet metal piece, and insert the screw insertion hole so that it is located directly below this screw insertion hole Are formed in the printed wiring board and screw holes are formed in the support on the back side of the printed wiring board, and screws are inserted into the screw holes of the support through the screw insertion holes of the printed wiring board. A grounding structure for a printed wiring board, wherein the piece is in contact with an exposed portion of the ground pattern.   The grounding structure for a printed wiring board according to claim 2, wherein a tip end portion of the grounding sheet metal piece is bent to form a support leg portion that comes into contact with the insulating coating surface of the printed wiring board.   The middle part of the sheet metal piece for grounding is bent to form a support leg that contacts the insulating coating surface of the printed wiring board, and the half on the tip side of the support part of the sheet metal piece is floated above the exposed part of the ground pattern. The base half of the sheet metal piece is floated above the insulating coating surface of the printed wiring board, and the screw is inserted into the front half and the base half of the sheet metal piece. Forming holes, forming two screw insertion holes on the printed wiring board and two screw holes on the support on the back side of the printed wiring board so as to be positioned directly below these screw insertion holes, The screw is inserted into one of the screw holes of the support through one of the screw insertion holes of the printed wiring board from either of the screw insertion holes of the front end side half piece or the base end side half piece. Claim 2 Ground structure of the printed wiring board.   The ground structure for a printed wiring board according to claim 4, wherein a screw insertion hole is formed in a half piece on the base end side of the sheet metal piece so as to be close to the base end portion of the sheet metal piece.

Images