JPH10163593A - How to ground the printed circuit board - Google Patents

Abstract

(57) [PROBLEMS] To provide a method for grounding a printed circuit board which can ensure reliable conduction between a ground pattern and a ground metal frame by a simple method and maintenance-free for a long period of time. When a ground pattern (1a) formed on a printed circuit board (1) is grounded to a ground metal frame (2),
A frame insertion window 1b is opened in the ground pattern forming area of the printed board in advance, and two soft copper wires 4 are laid across the insertion window, and both ends are soldered to the board side ground pattern, The fastening bolt 3 inserted between the two soft copper wires is screwed to the end face of the ground metal frame to hold and fix the soft copper wire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for grounding a printed circuit board on which electronic circuit components are mounted.

[0002]

2. Description of the Related Art When a printed circuit board needs to be grounded, a ground pattern to be grounded together with a circuit conductor pattern is formed on the surface of the printed circuit board in advance, and the printed circuit board is mounted on an apparatus in an assembled state. And a ground metal frame provided on the device side.

FIGS. 2A and 2B show a conventional printed circuit board ground connection structure. In the figure, 1 is a printed board, 1a is a ground pattern formed on the back side of the printed board 1, 2 is a ground metal frame on the device side which is protected and earthed, 3 is a fastening bolt which also serves as a ground conductive member, A bolt hole is drilled in advance in an area where a ground pattern 1a corresponding to the ground metal frame 2 is formed, and the bolt hole is positioned on the ground metal frame 2 at an assembled position.
a is superimposed on the end face of the ground metal frame 2, and in this state, the fastening bolt 3 is screwed into the end face of the metal frame 2 and fastened. And clamp between them. Thereby, the ground pattern 1 a of the printed circuit board 1 is conducted to the ground metal frame 2.

As a method for grounding the printed circuit board and a means for further improving the conductivity between the ground pattern and the ground metal frame, through holes formed by filling solder around bolt holes formed in the printed circuit board are provided. Japanese Patent Laid-Open No. 5-206601 discloses a structure in which a ground pattern is conducted to a grounding metal frame using the through hole as a conduction path.

[0005]

However, the method of directly fastening the printed circuit board to the ground metal frame with the fastening bolts to ground the ground pattern as described above has the following problems. That is, on the printed circuit board,
Copper-clad laminates in which a copper foil is adhered to an insulating substrate formed by impregnating a base material such as paper or glass cloth with phenol, epoxy resin, or the like are widely used. However, such a printed circuit board deteriorates due to shrinkage that occurs after resin molding and plastic deformation of the board due to long-term fastening of the bolt, thereby changing the thickness of the board. The contact pressure with the ground pattern decreases. For this reason, when considering the compliance with the safety standard of the product, sufficient reliability cannot be secured with the above-mentioned conventional ground connection structure.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to solve the above-mentioned problems and to provide a simple method and maintenance-free for a long period of time between a ground pattern and a ground metal frame. It is an object of the present invention to provide a method for grounding a printed circuit board, which can ensure a good conduction.

[0007]

According to the present invention, a soft conductor piece having an end electrically connected to a ground pattern surface of a printed circuit board is drawn out on an end surface of a ground metal frame according to the present invention. At this position, the soft conductor piece is clamped and fixed by a fastening bolt screwed to the end face of the ground metal frame, and specifically, it is preferable to implement the following manner.

1) The soft conductor piece is a soft copper wire plated with solder, and the end of the soft copper wire is soldered to a ground pattern on a printed circuit board. 2) An insertion window for the ground metal frame is opened in the ground pattern forming area of the printed circuit board, and two soft copper wires are laid across the insertion window, and both ends are soldered to the board-side ground pattern, The fastening bolt inserted between the two soft copper wires is screwed into the end face of the ground metal frame to clamp and fix the soft copper wire.

According to the above grounding method, the ground pattern of the printed circuit board is conducted to the ground metal frame via the soft copper wire (soft conductor piece), and the soft copper wire is connected between the ground metal frame and the fastening bolt by bolting. It is clamped and fixed between. Therefore, the shrinkage of the molded resin that has occurred on the printed circuit board due to aging during long-term use has no effect on the continuity of the ground connection. Since it is slightly plastically deformed and comes into close contact with the end face of the ground metal frame and the fastening bolt, a good conduction state can be maintained for a long time.

In addition, by using a soft copper wire similar to a jumper wire as a connection conductor, mounting (laying and soldering) on a printed circuit board can be easily performed by an automatic assembly process without relying on manual work. By laying two soft copper wires and inserting a fastening bolt between them, the soft copper wire can be stably fixed between the bolt head of the fastening bolt and the ground metal frame.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In the drawings of the embodiment, the same members corresponding to FIG. 2 are denoted by the same reference numerals. In this embodiment, a frame insertion window 1b for inserting the ground metal frame 2 from below is formed in advance in the area of the ground pattern 1a of the printed circuit board 1, and furthermore, the frame insertion window 1b extends across the center of the frame insertion window 1b. Two soft copper wires 4 are laid in parallel on the upper surface side of the printed circuit board 1, and both ends are inserted into holes formed in the substrate, and are joined to the ground pattern 1 a by solder 5 on the back surface side of the substrate. In addition, soft copper wire 4
Is previously plated with solder, and the interval between the two copper wires is set to an interval corresponding to the diameter of the shaft of the fastening bolt 3.

When grounding the printed circuit board 1 to the ground metal frame 2, first, the frame insertion window 1b
The printed circuit board 1 is positioned so that the soft copper wire 4 laid across the board rests on the end face of the ground metal frame 2 and is fixed at the assembly position. Next, the fastening bolt 3 is inserted from above into the two strips of annealed copper wire 4 and screwed into the grounding metal frame 2.
Two soft copper wires 4 are sandwiched and fixed between the bolt head of the fastening bolt 3 and the ground metal frame 2. In addition, if necessary, the soft copper wire 4 is fastened together with the fastening bolt 3 with a contact metal (washer) interposed therebetween.

As a result, the ground pattern 1a of the printed circuit board 1 is conducted and grounded to the ground metal frame 2 via the soft copper wire 4.

[0014]

As described above, according to the grounding method of the present invention, the continuity between the ground pattern formed on the printed circuit board and the grounded metal frame can be obtained without being affected by the aging of the printed circuit board itself. Can be maintained stably and maintenance-free for a long time, and the reliability of products can be improved in terms of safety standards.

[Brief description of the drawings]

1A and 1B are configuration diagrams of an embodiment of the present invention, wherein FIG. 1A is a longitudinal sectional view of a ground connection portion of a printed circuit board, and FIG. 1B is a plan view of FIG.

FIG. 2 is a configuration diagram of a ground connection portion of a conventional printed circuit board, where (a) is a longitudinal sectional view of the ground connection portion of the printed circuit board, and (b) is a plan view of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed circuit board 1a Ground pattern 1b Frame insertion window 2 Ground metal frame 3 Fastening bolt 4 Soft copper wire 5 Solder

Claims (3)

[Claims] 1. A grounding method for connecting a ground pattern formed on the surface of a printed circuit board to a ground metal frame, wherein a soft conductor piece having an end electrically connected to the ground pattern surface of the printed circuit board is connected to the ground metal frame. A method of grounding a printed circuit board, wherein a soft conductor piece is pulled out on an end face, and is fixed at this position by a fastening bolt screwed into an end face of a grounded metal frame. 2. The printing method according to claim 1, wherein the soft conductor piece is a soft copper wire plated with solder, and an end of the soft copper wire is soldered to a ground pattern on a printed circuit board. How to ground the board. 3. The grounding method according to claim 2, wherein an insertion window of the ground metal frame is opened in the ground pattern forming area of the printed circuit board, and two soft copper wires are laid across the insertion window. A printed circuit board, wherein both ends are soldered to a ground pattern on the board side, and a fastening bolt inserted between the two soft copper wires is screwed into an end face of the ground metal frame to hold and fix the soft copper wire. Grounding method.