JPH0414293A - Shielding case - Google Patents

Abstract

PURPOSE:To fit shielding cases to a substrate in a close contact state by using a less number of screws by bending the shielding cases in the directions in which the central parts of the end faces of the cases faced to the substrate are projected. CONSTITUTION:An upper and lower shielding cases 20 and 21 are formed by bending the cases 20 and 21 in the directions in which the central parts of their end faces 24 and 25 faced to a printed wiring board 22 are projected after plating. After the upper and lower cases 20 and 21 are respectively arranged on the surface 26 and rear 27 sides of the board 22, the cases 20 and 21 are fixed to each other with the board 22 in between by tightening screws 29. The central parts of the end faces 24 and 25 are first brought into contact with an earthing pattern and, when both end sides in the length direction of the cases 20 and 21 are fixed to each other by means of the screws 29, the cases 20 and 21 are deformed by the elasticity of the plastic material and the end faces 24 and 25 are brought into close contact with the earth pattern from the central parts to both end sections. Therefore, the entire surfaces of the end faces 24 and 25 are brought into close contact with the earth pattern even when no screw is used for the central parts of the cases 20 and 21 and the inside and outside of the cases 20 and 21 can be shielded well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an improvement in a shield case formed of a plastic molded product.

(Prior art) Radio equipment such as mobile radio telephones suffer from radio noise interference (E
In order to prevent MI), the main circuit section is covered with a shield case.

This shield case is generally made of a metal member such as aluminum die-casting, but in recent years there has been an increasing demand for smaller and lighter equipment, and in response to this, it has been made by applying metal plating to a plastic molded product. There are many cases where this is the case.

FIGS. 3 and 4 show this type of conventional shield case and its mounting structure.

In these figures, 1 is an upper shield case, 2 is a lower shield case, and 3 is a printed wiring board.

The upper and lower shield cases 1 and 2 are formed by applying nickel plating to a molded product of ABS resin for plating. Further, the upper shield case 1 is formed with a seat 7 having an insertion hole 6 for the screw 5, and the lower shield case 2 is formed with a seat 9 corresponding to the seat 7 and having a screw hole 8 for engaging the screw. It is formed.

The upper shield case 1 is arranged on the front surface 11 side of the printed wiring board 3, the lower shield case 2 is arranged on the back surface 12 side of the printed wiring board 3, and the upper and lower shield cases 1.
2 are jointly fastened to the printed wiring board 3 with screws 5.

By the way, when plating plastic molded products, the temperature of the plating bath is about 60'C, and if plating is performed at this temperature, residual stress that remains in the molded product during injection molding performed at high pressure and high temperature. appears due to the influence of plating temperature, and the third
As shown in the figure, the upper and lower shield cases 1.2 are often warped in a direction in which the center portion of the end surface 15.1B on the side facing the printed wiring board 3 is concave. Therefore, as shown in FIG. 4, by fixing the upper and lower shield cases 1 and 2 to the printed wiring board 3 with screws 5 not only at both ends in the longitudinal direction but also at the central portion, the central portion of the end surface 15. It was made to prevent a gap from occurring between the printed wiring board 3 and the printed wiring board 3.

However, screwing both ends and the center of the upper and lower shield cases 12 in this way not only increases the number of screws but also increases the number of man-hours required for screwing the upper and lower shield cases 1.2. there were.

(Problems to be Solved by the Invention) As described above, in the above-described shield case, it is necessary to fix the shield case to the board using a large number of screws so as not to create a gap between the shield case and the board.

The present invention has been made in view of these conventional drawbacks, and it is an object of the present invention to provide a shield case that can be attached in close contact with a board using fewer screws than the conventional case.

[Structure of the Invention] (Means for Solving the Problems) In the present invention, in a shield case formed by applying metal plating to a plastic molded product, the shield case has a central portion of the end face facing the substrate. The structure is curved in the protruding direction.

(Function) In the shield case of the present invention, the central part of the end surface contacts the board first, and when both ends of the shield case are screwed onto the board, the shield case is made of plastic.
Due to the elasticity of the hook, the end faces from the center to both ends are deformed in a direction that brings them into close contact with the substrate.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 and 2.

Figure 1 is a side view showing the shield case before and after assembly, Figure 2
The figure is a perspective view of the assembled shield case.

In these figures, 20 is an upper shield case, 21 is a lower shield case, and 22 is a printed wiring board.

The upper and lower shield cases 20 and 21 are formed by applying nickel plating to a molded product of ABS resin for plating.
As shown in Figure (a), in the state after plating, the center portion of the end surface 2425 on the side facing the printed wiring board 22 is curved in a protruding direction.

As a manufacturing method for these upper and lower shield cases 20.21, it is also possible to directly manufacture curved molded products (shield cases 20.21 before metal fitting, hereinafter the same) using a mold. However, this method complicates the mold and increases the number of man-hours and costs for mold processing.

Therefore, using a normal annealing jig, we
A simple and good method is to bend it in the direction in which the central part of the blade protrudes. That is, after performing injection molding, instead of leaving the molded product as it is to cool it, it is preferable to use an annealing jig to forcibly cool the molded product in a warped state. still,
The amount by which the molded product is warped is slightly greater than the amount by which the molded product is warped in the opposite direction during the plating process, but this amount is determined by trial production.

Upper and lower shield cases 20, 2 shaped as above
1, an upper shield case 20 is arranged on the front surface 26 side of the printed wiring board 22, and a lower shield case 2 is arranged on the back surface 27 side.
1 are arranged and fastened together to the printed wiring board 22 with screws 29 (FIG. 2).

In this case, the upper and lower shield cases 20.21 have their respective end surfaces 24.25 centered on the printed wiring board 22 first.
is in contact with the earth pattern (not shown),
Attach both longitudinal ends of the shield case 20 and 21 with screws 2.
When tightened at 9, the elasticity of the plastic will cause case 2 to tighten.
0.21 is deformed and the end face 24 from the center part to both ends
．． 25 is in close contact with the ground pattern. Therefore, even if the center portion of the shield case 20.21 is not screwed, the entire end surfaces 24.25 of the shield cases 20, 21 are in close contact with the ground pattern, and the shield case 20.21 is in close contact with the ground pattern.
21 can be well shielded inside and outside.

[Effects of the Invention] As explained above, in the shield case of the present invention, when both ends of the shield case are screwed to the board, the central part of the end face facing the board comes into contact with the board, and then deforms due to the elasticity of the plastic. The end faces of the case from the center to both ends are in close contact with the board. Therefore, by simply screwing only both ends of the shield case to the board, the inside and outside of the shield case can be reliably shielded.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining one embodiment of the present invention, and FIGS. 1(a) and 2(b) are side views illustrating the front and rear views of how the shield case is attached to the board, and FIGS. The figure is a perspective view of the shield case attached to the board. FIG. 3 is a perspective view of a conventional shield case, and FIG. 4 is a perspective view of the shield case of FIG. 3 attached to a board. 20... Upper shield case 21... Lower shield case 22... Printed wiring board (board) 24... End face of upper shield case 25... End face of lower shield case Patent attorney Noriyuki Chika Sanno Figure 1 Figure 3 Figure 2 Figure 4

Claims (1)

[Claims] In a shield case that is formed by applying metal plating to a plastic molded product and is attached to the printed wiring board so as to cover electronic components on the printed wiring board, the shield case is located at the center of the end face of the side facing the printed wiring board. A shield case characterized in that a portion thereof is curved in a protruding direction.