JPS62237Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic shielding structure for an electric circuit block provided within a printed wiring board and requiring electromagnetic shielding.

In the conventional electromagnetic shielding structure, the printed wiring board is sandwiched between the parts mounting surface and the case is inserted into a small square hole or round hole 2 provided in the printed wiring board 1 as shown in Fig. As shown, a claw-like protrusion 4 provided on the case 3 is inserted and fixed with solder. As shown in FIGS. 3a and 3b, a cover 5a having a folded part 6 in whole or in part is placed on the printed pattern surface corresponding to the case 3, and the folded part 6 is placed on the cover 5a.
Generally, the cover 5a, which does not have a folded part, is soldered and fixed to the ground pattern 7 provided on the printed wiring board at several locations, or the cover 5a, which does not have a folded part, is soldered to the claw-shaped protrusion 4 of the case 3. be. FIG. 4 is a sectional view showing the conventional structure after the printed wiring board 1, case 3, and covers 5a and 5b are assembled.

According to this method, the case 3 and the covers 5a and 5b
Since a printed wiring board is interposed between the cover and the printed wiring board, partial soldering of the contact surfaces sandwiching the printed wiring board tends to result in uneven gaps due to the short engagement length of the contact parts. This is a fatal cause of the overall reduction in the electromagnetic shielding effect. In addition, the method of soldering the cover has the disadvantage that it is difficult to inspect the printed pattern surface when checking circuit connections, replacing parts, or finding faulty circuits during adjustment inspections and maintenance inspections.

Another common method is to incorporate an independent unitized structure in which the electric circuit block that requires electromagnetic shielding is mounted on a separate printed wiring board and housed in a shield case. . This method is very effective as an electromagnetic shielding effect, but on the other hand, it increases the number of printed wiring boards used. The equipment that implements this unit requires assembly work to be completed at the same time based on the manufacturing schedule, and requires multiple work routes for assembly work.
There is duplication of assembly work and electrical connection work, which increases parts costs, manufacturing man-hours, and management man-hours. or,
The device configuration becomes complicated because there are multiple components to be assembled, and because the device is mounted on the printed wiring board that makes up the device, it is difficult to conduct electrical inspections on the side of the parts replacement circuit inside the unit. It has its drawbacks.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide a case cover structure within a printed circuit board that has a simple structure and has a stable electromagnetic shielding effect.

The present invention will be explained below with reference to the drawings.

Figure 5 shows the structure of the part of the printed wiring board in which the electric circuit block that requires electromagnetic shielding is mounted, Figure 6 shows the structure of the case, and Figure 7 shows the structure of the cover. It is a diagram showing the main points. A claw-like protrusion 16 is provided on the metal case 15 in a long and narrow rectangular groove 13 and a through-hole hole 14 provided all around the electric circuit block 12 that requires electromagnetic shielding provided in the printed wiring board 11.
Insert the elongated protrusion 17 having a slightly smaller external dimension into the rectangular groove 13, and insert the through-hole hole 1 on the printed pattern side of the printed wiring board 11.
At part 4, the claw-like protrusion 16 of the case 15 is fixed with solder. Next, as shown in FIG. 8, the external dimensions 18 of the case 15 are measured from the component mounting surface and pattern surface sides, respectively, with the printed wiring board 11 as the center.
Dimensions 18c, 18 slightly smaller than a, 18b
Covers 19a and 19b are provided with a folded portion 20 having a substantially L-shaped structure on the inside by bending the edges d.
along the outer periphery of the case 15. cover 1
The folded portions 20 of the case 15 are expanded to the outer dimensions 18a and 18b of the case 15, and are held in close contact with each other over the entire circumference. FIG. 8 is a sectional view showing the structure after the printed wiring board 11, case 15, and covers 19a and 19b are assembled.

According to the present invention, as shown in FIG. 8, an electric circuit block that requires electromagnetic shielding is entirely surrounded by a case 15 and a cover 19.
It is a structure that is completely independently isolated and housed within the interior of the interior of the interior of the interior of the interior of the interior of the interior of the interior of the interior of the interior of the interior of the interior of the interior of the interior of the interior of the interior of the vehicle. This means that even if the contact portions between the case 15 and the printed wiring board 11 are not aligned after they are fixed by soldering, there is little adverse effect on the electromagnetic shielding effect. Further, since spring pressure can be applied to the cover from the outside over the entire surface thereof, it is possible to use iron plate or brass plate, which is a general metal material that is thicker than the spring material. Therefore, the structure has sufficient strength and has a stable electromagnetic shielding effect comparable to that of a unitized electromagnetic shielding structure, with minimal deformation of the cover due to spring pressure and almost no negative effect on the electromagnetic shielding effect. It is. Furthermore, the shielding effect of the cover 19b is due to the structure in which it closely engages with the case 15 at the position passing through the rectangular groove 13, as is clear from FIG. It doesn't matter the size of
By applying a simple contact prevention device such as attaching an insulating sheet to the inside of the cover 19b, the substrate 1
The gap between the pattern surface and the pattern surface having the electric circuit 1 can be made sufficiently small. Therefore, the volume of the shield case can be reduced, and the device itself implementing the present invention can be made smaller. Furthermore, since the cover is easily attachable and detachable, parts replacement and circuit inspection are easy. It is clear that the above advantages have an effective effect on maintaining stable electrical characteristics.

[Brief explanation of the drawing]

1 to 4 are diagrams showing an example of a conventional structure. The figure is a three-dimensional view showing the external structure of the case, and FIG. 3 is a three-dimensional view showing the external structure of the cover. FIG. 4 is a sectional view showing the structural state after assembling the case and cover based on the printed wiring. Figures 5 to 8 are diagrams showing the present invention. Figure 5 is a plan view showing the overall structure of the portion of the printed wiring board in which an electric circuit block that requires electromagnetic shielding is mounted, and Figure 6 is a diagram showing the present invention. Three-dimensional diagram showing the external structure of the case,
FIG. 7 is a three-dimensional view showing the external structure of the cover.
FIG. 8 is a sectional view showing the structural state after the case and cover are assembled to the printed wiring board. In the figure, 11... printed wiring board, 12...
Electric circuit block, 13... Rectangular groove, 14...
Through-hole hole, 15...Case, 16...Claw-shaped protrusion, 17...Elongated protrusion, 19a, 19b
. . . Cover, 20 . . . Folded portion.

Claims (1)

[Scope of utility model registration request] A plurality of elongated rectangular grooves are continuously provided with a slight gap around the circuit block that requires electromagnetic shielding in the printed wiring board, and an inverted L is formed around the periphery of the electromagnetic shielding case that passes through the rectangular grooves. An electromagnetic shielding cover with bendable spring properties is inserted along the outer surface of the case from both the top and bottom directions, and the cover inserted from the bottom is inserted into the case at a position where it passes through the rectangular groove. Electromagnetic shielding structure characterized by close engagement over the entire peripheral area.