JPH0515490U - Wiring board shield structure - Google Patents

Abstract

(57) [Summary] [Purpose] Preventing the leakage of unwanted radiation from the shield case that prevents the diffusion of unwanted radiation. [Structure] Circuit components that generate unnecessary radiation are arranged on the printed circuit board 21. This circuit component is covered with shield cases 22a and 22b that absorb unnecessary radiation. Printed circuit board 21 of shield cases 22a and 22b
A groove is formed all around the end facing the shield mesh 3
Set 0. The shield mesh 30 has conductivity and elasticity. Therefore, when the printed board 21 is pressed, it is elastically deformed and the shield case 22
The printed circuit board 21 and a, 22b are brought into close contact with each other.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a shielded structure of a wiring board that blocks unnecessary radiation generated from a semiconductor integrated circuit.

[0002]

[Prior Art]

 FIG. 9 is a perspective view showing a first conventional example. A plurality of circuit components (not shown) are mounted on the print substrate 1. The plurality of circuit components are covered by a metal shield case 2 having a notch 5 at a position corresponding to a circuit wiring 4 to be described later for each related circuit component. It is fixed by solder 3 on top. The circuit components are connected by the circuit wiring 4 formed on the printed board 1.

Circuit components that handle high frequencies and pulses generate unnecessary radiation. As a result, other signals may interfere with each other to generate noise, or noise may enter the signal, resulting in malfunction. Also, in the case of wireless devices, the transmitted and received audio contains noise.

The shield case 2 is used to prevent the influence of such unwanted radiation. The shield case 2 is made of metal and has a function of absorbing unnecessary radiation.

As shown in FIG. 9, if the shield case 2 is fixed on the printed circuit board 1 with the solder 3, unnecessary radiation does not leak from the gap between the shield case 2 and the printed circuit board 1. However, if a circuit component in the shield case 2 fails, first melt the solder 3, remove the shield case 2, then repair or replace the circuit component, and weld the shield case 2 with the solder 3. Must. Therefore, there is a problem that the number of steps is large and complicated. Further, since heat is applied, there is a problem that the heat damages the circuit components.

FIG. 10 is an exploded perspective view showing a second conventional example, and FIG. 11 is a sectional view showing the second conventional example. A shield case 2a made of metal is arranged on the printed circuit board 1a so as to cover a plurality of circuit components 9. In order to cover the circuit component 9 on the back surface of the printed circuit board 1a in a housing 6 made of metal, A shield case 2b made of metal is formed at a position corresponding to the component 9. Each of the shield cases 2a and 2b has cutouts 5a and 5b at positions corresponding to the circuit wiring 4a connecting the circuit components 9 formed on the printed board 1a.

The printed circuit board 1 a is inserted into the housing 6 and fixed. At this time, screw holes 7b are formed commonly to the printed circuit board 1a, the shield case 2b, and the housing 6 at positions corresponding to the screw holes 7a of each shield case 2a. The printed circuit board 1a is fixed to the housing 6 by inserting screws 11 described below into the screw holes 7a and 7b.

As shown in FIG. 11, when the screw 11 is inserted into the screw holes 7a and 7b, distortion occurs between the printed circuit board 1a and the shield cases 2a and 2b, so that the printed circuit board 1a and the shield cases 2a and 2b are distorted. There is a possibility that gaps 8a and 8b will be generated in the space. Leakage of unnecessary radiation occurs due to the formation of the gaps 8a and 8b.

[0009]

[Problems to be solved by the device]

 FIG. 12 is a perspective view showing a third conventional example, and FIG. 13 is an enlarged perspective view showing the third conventional example. In order to prevent the gaps 8a and 8b shown in the second conventional example from occurring, grooves are formed in the shield case 2c except for the cutouts 5c and 5d, which are in contact with the printed circuit board (not shown), and the shield meshes 10a and 10b are formed. Insert. The shield meshes 10a and 10b are made by wrapping an elastic insulating material in a metal wire. By pressing the shield meshes 10a and 10b against the printed circuit board, the formation of the gaps 8a and 8b can be prevented.

However, there is a problem that the number of shield meshes 10a and 10b to be inserted into the groove increases as the number of notches 5c and 5d increases, and the number of man-hours for attaching the shield meshes 10a and 10b increases. Also, as shown in FIG. 13, when the wires on the surfaces of the shield meshes 10a and 10b are loosened at the cuts and the shield case is pressed against the printed circuit board, it breaks through the insulating film on the circuit wiring and contacts the circuit wiring. However, there is also the problem of short circuits.

An object of the present invention is to solve the above problems and to provide a shield structure for a wiring board that does not short-circuit the signal line and the conductive case.

[0012]

[Means for Solving the Problems]

 The present invention provides a wiring board having a circuit element and a signal line connected to the circuit element, a conductive case that covers the circuit element and has a recess formed in the signal line portion, and a wiring board of the conductive case. This is a shield structure for a wiring board, which is characterized in that it has conductive wires all around the opposite ends.

Further, the present invention is the shield structure for a wiring board according to claim 1, wherein an interposition member made of an electrically insulating material is arranged in the recess of the conductive case.

[0014]

[Action]

 According to the invention, the wiring board has a circuit element and a signal line connected to the circuit element, and the circuit element has a recess formed in a signal line portion connected to the circuit element. It is covered by a conductive case. The conductive case has a conductive wire around the entire circumference of the end facing the wiring board, and blocks unnecessary radiation generated in the conductive case.

Further, according to the invention, an interposition member made of an electrically insulating material is arranged in the recess of the conductive case, and the interposition member prevents a short circuit between the signal line and the electroconductive case.

[0016]

【Example】

 1 is an exploded perspective view showing the first embodiment, FIG. 2 is an enlarged perspective view of the shield cases 22a and 22b shown in FIG. 1, and FIG. 3 is a cross section of the shield mesh 30 shown in FIG. It is a figure. On a printed circuit board 21 which is a wiring board, a plurality of circuit elements (not shown), which are circuit elements, are placed on both front and back surfaces. The circuit components on the front surface 21a of the printed circuit board 21 are covered with a shield case 22a made of metal, which is a conductive case, and the circuit components on the back surface 21b are located at positions corresponding to the circuit components of the housing 26 made of metal. It is stored in a shield case 22b made of metal formed on the.

The shield cases 22a and 22b are provided with notches 25a and 25b, which are recesses, at positions corresponding to circuit wiring which is a signal line formed on the printed circuit board 21 which connects circuit components. ing. Further, a groove 28 is formed on the entire circumference of the ends of the shield cases 22a and 22b facing the print substrate 21, and a shield mesh 30 which is a conductive wire is arranged on the entire circumference.

The shield mesh 30 is made of an electrically insulating material 30a having elasticity such as rubber at the center, and a metal mesh 30b covers the electrically insulating material 30a. The diameter R of the shield mesh 30 is selected to be larger than the depth D of the groove 28, and the portion of the shield mesh 30 that does not face the groove protrudes from the shield cases 22a and 22b.

The shield case 22a of the printed circuit board 21 is fixed and the printed circuit board 21 is fixed to the housing 26 at positions corresponding to the screw holes 27a formed in the shield case 22a and the screw holes 27a of the printed circuit board 21. The screw holes (not shown) and the screw holes 27b formed at positions corresponding to the screw holes 27a of the housing 26 are fixed by inserting screws (not shown).

The screw presses the shield case 22a against the printed circuit board 21 and the printed circuit board 21 against the shield case 22b.

Since the electrically insulating material 30 a at the center of the shield mesh 30 has elasticity, the shield mesh 30 is elastically deformed according to the pressing force of the screw, and the shield cases 22 a and 22 b and the printed circuit board 21 are separated from each other. Since no gap is formed between them, leakage of unnecessary radiation can be prevented.

FIG. 4 is a diagram showing a second embodiment of the present invention. In addition to the first embodiment, in this embodiment, an insulator 29 which is an inclusion is sandwiched between the circuit wiring 24 and the notches 25a and 25b. When the shield cases 22a and 22b are pressed against the printed board 21, the shield mesh 30 may be pulled in the arrow A direction or the arrow B direction. At this time, the shield mesh 30 in the cutouts 25a, 25b floats up from the cutouts 25a, 25b of the shield cases 22a, 22b and breaks the insulating film (not shown) on the circuit wiring 24, so that the circuit wiring 24 and the shield mesh 30 are separated. May short circuit.

Therefore, by disposing the insulator 29 in the notches 25a and 25b, it is possible to prevent the shield mesh 30 from rising and the short circuit between the circuit wiring 24 and the shield mesh 30 due to the rising.

FIG. 5 is a perspective view of an insulator 29a used in the modification of the second embodiment, and FIG. 6 is a plan view showing an example of use of the insulator 29a used in FIG. The insulator 29a has a groove 31, and the groove 31 can be sandwiched between the notches 25a and 25b of the shield cases 22a and 22b. Even when the insulator 29a is used to prevent the floating of the shield mesh 30 and the short circuit between the circuit wiring 24 and the shield mesh 30, the same effect as that of the above-described embodiment can be obtained.

FIG. 7 is a side view showing the shapes of the notches 25a and 25b of the shield cases 22a and 22b, and FIG. 8 is a side view showing the shape of the notches 25c of the shield case 22c used in another embodiment. It is a figure. Although the notches 25a and 25b shown in FIG. 7 are trapezoidal, the notch 25c shown in FIG. 8 is rectangular. The notches 25a, 25b, 25c may have any shape, and the shape is not limited to these.

Although not described in the present embodiment, when unnecessary radiation is absorbed by the shield cases 22a and 22b, an alternating current is generated in the shield cases 22a and 22b. This alternating current is removed from the circuit wiring (not shown) on the printed board 21 through the housing 26 connected to the ground potential.

[0027]

[Effect of the device]

 According to the present invention, the conductive case is provided on the entire circumference of the end portion that faces the wiring board of the conductive case that covers the circuit element and has the recess formed in the signal line portion connected to the circuit element. Therefore, unnecessary radiation generated from the circuit element on the wiring board is blocked. Further, according to the present invention, by disposing the interposition member made of an electrically insulating material in the recess of the conductive case, it is possible to prevent a short circuit between the conductive case and the signal line.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a first embodiment.

FIG. 2 is a shield case 22a, 22b shown in FIG.
FIG.

FIG. 3 is a cross-sectional view of the shield mesh 30 shown in FIG.

FIG. 4 is a view showing a second embodiment of the present invention.

FIG. 5 is an insulator 29 used in a modification of the second embodiment.
It is a perspective view of a.

FIG. 6 is a plan view showing a usage example of an insulator 29a used in FIG.

FIG. 7 is a cutout 25 of the shield cases 22a and 22b.
It is a side view which shows the shape of a, 25b.

FIG. 8 is a shield case 22c used in another embodiment.
It is a side view which shows the shape of the notch 25c.

FIG. 9 is a perspective view showing a first conventional example.

FIG. 10 is an exploded perspective view showing a second conventional example.

FIG. 11 is a sectional view showing a second conventional example.

FIG. 12 is a perspective view showing a third conventional example.

FIG. 13 is an enlarged perspective view showing a third conventional example.

[Explanation of symbols]

 21 Printed Circuit Board 22a, 22b, 22c Shield Case 24 Circuit Wiring 25a, 25b, 25c Notch 26 Housing 29, 29a Insulator 30 Shield Mesh

Claims (2)

[Scope of utility model registration request] 1. A wiring board having a circuit element and a signal line connected to the circuit element, a conductive case which covers the circuit element and has a recess formed in a signal line portion, and a wiring board of the conductive case. A shield structure for a wiring board, characterized in that a conductive wire is provided on the entire circumference of an end portion opposite to. 2. The shield structure for a wiring board according to claim 1, wherein an interposition member made of an electrically insulating material is arranged in the recess of the conductive case.