JPH03127899A - Mounting structure of conductive member onto case body - Google Patents

Abstract

PURPOSE:To make it possible to obtain a uniform continuity between a case body and a member by a method wherein axis parts protruded previously on the case body having a conductivity and the member, which is provided with opening parts to be inserted these axis parts therein and whose contact parts with the case body have a conductivity, are provided and the member is pressure-welded to the case body by a pressure welding means. CONSTITUTION:Conductive films 1b and 1c of a case body 1 are respectively applied on the inner side surface and the outer side surface of the case body 1 and a conductive film is continuously applied on mounting pedestals 10 as well. After a printed wiring board assembly 2 is fitted into stud screws 11 of the pedestals 10 provided on the case body 1, the pedestals 10 are respectively clamped using a washer 13 and a nut 12 and the assembly 2 is coupled with the case body 1. In this case, earth lands 2a to 2e of the assembly 2 are installed in an area to correspond sufficiently to mounting surfaces 10a of the pedestals 10 and the respective surfaces to oppose of the earth lands 2a to 2e and the mounting surfaces 10a oppose to each other in a plane. Thereby, a uniform continuity can be obtained between the case body 1 and the member 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a structure for attaching a conductive member to a casing.For example, the present invention relates to a structure for attaching a conductive member to a housing. This is applied to a structure that connects the chassis ground and the case ground surrounding the circuit with low impedance.

[Conventional technology]

Since the plastic molded product itself is a poor conductor of electricity, if an electronic circuit such as a digital circuit is housed in the housing, the switching devices in that circuit It has not been possible to suppress the unnecessary radiated noise that is generated by the shielding or reflection effect of the housing. For this reason, when using a plastic molded casing, it is best to apply conductive treatment to the plastic casing itself, such as metal plating or conductive paint, so that the plastic casing has the same conductivity as a metal casing. It was normal.

However, even if it were possible to make the casing conductive, the secondary ground potential of the electrically conductive parts of the casing and the electronic circuits housed inside the plastic casing would be
It was extremely difficult to connect rigidly and with low impedance, such as grounding a metal casing. In other words, whether it is plating, conductive paint, or other conductive treatment, it is physically impossible to connect the conductive treated part of the casing and the ground potential of the electronic circuit with soldering, etc. Even if you use a one-sided connector that fits widely, when fitting the connector and conductive parts such as plating.

The conductive film is thin, a few μm thick, and the base material is soft plastic, so the insertion pressure can cause it to bite, cause the conductive coating to peel off, or conversely cause the conductivity to disappear. Ta.

For example, Japanese Patent Application Laid-open No. 62-24698 and Japanese Utility Model Application No. 61-98116 disclose structures for attaching a conductive member to a housing. Figure 4 shows a structure for attaching a conductive member such as an electronic circuit to a housing in Japanese Patent Application Laid-open No. 62-24698 and Japanese Utility Model Application No. 61-98.
96 is a cross-sectional view when the technique of No. 96 is applied. FIG. In Figure 4, (1) is a bottom casing of, for example, a portable personal computer, which is made of a plastic molded product with metal plating or conductive paint applied to its surface, and (2) is a bottom casing that is equipped with a semiconductor integrated circuit, etc. Printed wiring board assembly with electronic circuit (2d)
, (2e) is the ground land of the printed wiring pattern of the printed wiring board assembly (2), (4) is the boss provided for fixing the printed wiring board assembly (2) to the casing (11), and (5) is the ground land of the printed wiring pattern of the printed wiring board assembly (2). The screw (6) is a threaded insert for tightening the screw (5) on the tip end of the boss (4).

(7) is the protruding end surface of the boss (4).

FIG. 5 is a perspective view showing another conventional structure for attaching a conductive member to a housing based on the technique shown in FIG. 4.

In FIG. 5, the same reference numerals as in FIG. 4 indicate the same members. (
1a) is the bottom of the housing (1), (2a), (2b)
, (20), (2(1), (28) is the ground land of the printed wiring pattern of printed wiring board assembly (2), (3)
are Earthland (2a) and (2b).

(2C), (2d), (2e) are metal contact plates provided to release pressure; (3a) is a contact plate (
The contact surface provided on one side of 3) and in contact with the surface of the housing +11, and the contact surface (5) that is attached by tightening the printed wiring board assembly (2) and the contact plate (3) to the boss (4) of the housing fil. This is a screw for.

Figure 6 shows how the printed wiring board assembly (2) and the contact plate (3) in part a (attachment part of the contact plate (3)) in Figure 5 are attached to the boss (4) of the housing (1) with the screws (5). ) is a partially enlarged view clearly showing the tightened state.

FIG. 7 is a sectional view including the boss (4) of the casing (1), showing the state in which it is attached with the screw (5) of FIG. 6. 7th
In the figure, the same reference numerals as in FIG. 4 indicate the same members. (1
b), (IC) is a conductive coating such as metal plating or conductive paint applied to the casing +11, and αS is a decorative paint applied to the surface of the plastic casing that has been subjected to conductive treatment such as plating or conductive paint. be.

Next, we will provide a detailed explanation of the mounting structure.

In the conventional example shown in FIG. 4, a threaded insert fitting (6) for tightening the screw f511 is provided on the tip end side of the boss (4) integrally formed with the housing (1). And screw +51? : The printed wiring board assembly (2) can be attached to the boss (4) by tightening it against the insert fitting. However, as shown in Figure 8, even though the protruding end surface (7) of the boss (4) and the upper surface (9) of the insert fitting (6) are supposed to be in even contact with each other in the design, there is always a difference in level during manufacturing. A occurs. Therefore, the protruding end surface (7) of the boss (4) is connected to the earth land (2cl) of the printed wiring board assembly (2).
), (2・l) were generally not in contact with each other.

Furthermore, the electrical fit between the conductive coating applied to the boss (4) and the surface (7) of the tip and the insert fitting (6) is mostly due to the boss (4).
is a line contact of the circumference of . Therefore, the ground continuity is extremely insufficient, so the printed wiring board assembly (2) and the case (1)
) connection at ground potential was insufficient for practical use.

An example of improving this point is a conventional example as shown in FIG. That is, in general, the printed wiring board assembly (earth land (2a), which is at 2+ earth potential).

(2b), (20), (2d)

As shown in Figure 7, the casing is coated with plating or conductive paint (
A metal auxiliary tool such as a contact plate (3) that helps conduction is used on the bottom surface (1a) of the housing (1) to attach the conductive coating (11).
1b) with the contact pressure of the contact surface (3a) of the contact plate (3) to improve conduction. Of course, the contact plate (3) is in contact with the printed wiring board assembly (2). The contact plate (3) and the printed wiring board assembly (2) are arranged so that the printed wiring board assembly (2) is placed on the tip of the boss (4) as shown in Figures 6 and 7. Then, connect the earth land (2) of the printed wiring board assembly (2).
Install the contact plate (3) so that it is in contact with e). Then, insert the screw (5) into the insert fitting (6) provided on the boss (4).
), it is possible to join the contact plate (3) and printed wiring board assembly (2). In this way, the earth lands (2a) and (2b) of the printed wiring board assembly (2)
, (2c), (2d), (2e) and the bottom of the housing (11) are in contact with each other. ), (2t)), (20), (2a),
It is important that (2e) be connected to the conductive coating portion of the casing (1) with an impedance that has almost the same potential.

Modern electronic devices handle high frequencies ranging from several megahertz to several hundred megahertz, so when connecting the ground potential part of the printed wiring board (2) and the conductive processing part of the casing (11), there is a small amount of electricity between them. Even if resistance or stray capacitance occurs, it will generate a large impedance, and the unnecessary radiated noise current generated in the electronic circuit will flow into the conductive processing part of the housing (1), which is at ground potential. For this reason, unnecessary radiated noise currents may not attenuate and may instead become electromagnetic waves and emit into space.

Compared to the case without the contact plate (3) shown in Fig. 4, the one in Fig. 1 is different from the case where the contact plate (3) shown in Fig. ), (2e) will be electrically conductive at locations other than the junctions. Therefore, compared to the method of grounding shown in Figure 4, it can be expected to be more effective in suppressing unnecessary electromagnetic waves.

[Problem to be solved by the invention]

The conventional structure for attaching a conductive member to a casing uses an auxiliary tool such as a contact plate to improve the continuity between the plastic casing and the conductive member such as an electronic circuit. The contact between the contact plate and the contact plate was largely due to the contact pressure caused by the spring pressure of the contact plate, so the magnitude of the contact pressure made a difference in conduction. For this reason, there was a problem in that the suppression of unnecessary radiation noise often varied.

The present invention has been made to solve the above-mentioned problems, and its object is to obtain uniform conduction in the conductive portion between the conductive member and the casing.

[Means to solve the problem] and details that protrude in advance from the conductive casing.

An opening into which the shaft is inserted is provided, and a contact portion with the housing is electrically conductive.

The housing and the member are brought into pressure contact by a pressure contact means.

[Effect]

By inserting a shaft that is previously provided protruding from the casing into an opening provided in a member whose contact part with the casing is electrically conductive, and pressing them together, the contact part between the casing and the member is Electrical continuity is achieved.

[Embodiments of the invention]

FIG. 1 is a perspective view showing one embodiment of the present invention.
The figure is a sectional view taken along line nn' in FIG. FIG. 3 is a perspective view showing a method of attaching a decorative lid 0 ladder according to an embodiment of the present invention. Click on Figure 1, Figure 2, Figure 3,
The same reference numerals as in FIGS. 4, 5, and 6, which show the structure for attaching the conductive member to the housing of the conventional example and other conventional examples, indicate the same members.

In Figure 1, Ql is the mounting base on which the printed wiring board assembly (2) is installed, and (10a) is the printed wiring board assembly (2).
2) Earthland (2a), (2c), (2e)
(1) is the mounting surface that comes into contact with the printed wiring board assembly (
2) is a stud screw that serves as a shaft for fixing. Second
In the figure, α2 is a tightening nut used as a pressure welding means), (
13 is a tightening washer, α4 is embedded in the mounting base 1
This is the rotation stopper for the stud screw α9. This locking portion 0 also serves to prevent the stud screw αυ from being pulled out when it is pulled in the direction of the mounting surface (10a). (
IO is the inner joint part of the pedestal when molding the mounting pedestal 01 into the plastic casing, (171 is the decorative lid, and Oa is the fitting part provided on the casing (1). The conductive coating of the casing +11 (1b ), (IC) are coated and coated on the inner and outer surfaces of the housing (1).9.The conductive coating surface is also coated and coated continuously on the mounting pedestal +10.

Among them, in the conventional example shown in Figs. 1 and 2, after the printed wiring board assembly (2) is fitted into the mounting pedestal Ql provided in the housing (1) with all the stud screws 0υ, the washer is attached. The printed wiring board assembly (2) is coupled to the housing (11) by tightening the mounting pedestal α1 using the earth land (2''' of the printed wiring board assembly (2)). ) ? (21)) , (2C), (2
CL), (2e) are set to have an area sufficiently equivalent to the mounting surface (10a) of the mounting pedestal aO, and the ground land (2a) # (21)), (2(ri1(2)
d) , (261) and the mounting surface (10a) are flat and face each other, so that the conductive areas are in contact over an extremely wide area. On the other hand, assembling the printed wiring board (2
), the compression force between the conventional printed wiring board assembly (2) and the housing (1) becomes incomparably greater.

Furthermore, since the contact area is increased, it is possible to connect the printed wiring board assembly (2) and the housing (11) to earth potential with extremely low resistance.

By the way, the mounting pedestal 01 and the pedestal white part αG may or may not be hidden with a decorative cover, and may be used depending on the comfort. m”r As shown in Figure 3, prepare the decorative lid 0 ladder and fit it into the fitting part (1?) provided on the housing (1) using adhesive.Then, the outside of the housing (1) is coated with a conductive coating. A decorative coating (I51) was applied to hide the fitting part of the decorative lid U (
1? ) The parting line becomes visually invisible.

As shown in FIG. 7 and the like, conventionally, buttons on the housing (1) have been treated with a conductive coating by decorative coating.

Now, conductive treatment is applied to the plastic casing (1).

A plastic casing (1) is used to ensure good ground continuity.
To provide the mounting pedestal α1 during molding.

(11) This mounting pedestal αO does not have to be rectangular like the above-mentioned embodiment shown in FIG.
It doesn't matter if each book has a round (cylindrical) shape.

〔Effect of the invention〕

As described above, according to the present invention, the shaft portion is provided in advance on the housing so as to protrude, and this shaft portion is inserted into the opening provided in the member, so that the pressure contact means presses the housing and the member. Therefore, it has the effect of obtaining uniform conduction.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention, Fig. 2 is a partial sectional view of the structure shown in Fig. 1, and Fig. 3 is a perspective view of the structure shown in Fig. 1 showing the attachment of the decorative lid. Figure 4 is a cross-sectional view showing a conventional structure for attaching a conductive member to a housing, and Figure 5 is
The figure is a perspective view showing another conventional example of a structure for attaching a conductive member to a housing, FIG. 6 is a partially enlarged view of the structure shown in FIG. 5, and FIG. 7 is a sectional view of the structure shown in FIG. 5. , 8th
The figure is a sectional view of a boss portion of a conventional structure for attaching a conductive member to a housing. In the figure, (1) is the housing, (2) is the member, α9 is the shaft,
Q□(12) is a pressure welding means. inside. The same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] A casing, a part of which is electrically conductive, a shaft portion that projects from the casing in advance, and a member that is provided with an opening into which the shaft portion is inserted, and whose contact portion with the casing is electrically conductive. , a structure for attaching a conductive member to a casing, comprising pressure contact means for press-contacting the member and the casing.