JPH06283883A - Shielded board - Google Patents

Abstract

PURPOSE:To provide a shielded board whose shield process is made easy and shield effect is improved. CONSTITUTION:A circuit pattern 4 of a circuit board 2 to be shielded is enclosed with a shield member (shield case 16). The shield board is comprised of a grounding pattern 8 electrically connected to a grounding pattern part 9 of the circuit pattern, positioning frames 12A, 12B of a shield member formed along the grounding pattern and a shield member which is installed inside the positioning frame, fixed by a sealing member and shields a circuit pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield board for shielding a circuit pattern by installing a shield member.

[0002]

2. Description of the Related Art Generally, when forming a power supply device or the like by using a thick film circuit device, a shield measure is indispensable as a noise measure for an adjacent circuit. For example, the power supply is DC
Since a DC converter is used and such a circuit generates high frequency noise, sufficient shielding treatment is required.

Generally, as a measure for shielding a circuit device, a method of housing a circuit board in a metal case is generally used. The circuit board is housed in the metal case by fixing the circuit board in the metal case having a hermetically sealed structure and pulling out its leads in a non-contact state with the metal case. Naturally, it is necessary to take insulation measures between the metal case and the leads, and conventionally, methods such as air insulation and interposition of an insulating material have been taken.

In the case of air insulation, there is a method of forming a through hole in a metal case and installing a lead at a position corresponding to the hole. Such a method naturally requires high positional accuracy, and it is necessary to increase the size of the through hole in order to absorb some vibration. However, increasing the size of the through hole poses a problem of noise leakage from this portion. Further, the interposition of the insulator complicates the treatment, and after the treatment of the insulator, it becomes difficult to open and close the metal case, and in order to open and close the metal case, a device for that is required.

[0005]

From such a background,
By installing a shield member on the surface of the circuit board,
It has been proposed to cover the entire circuit pattern or selectively with a shield member. In the shield of such a shield member, the shield effect is impaired depending on the connection between the circuit pattern and the ground pattern, the mounting structure thereof, and the like, and in mass production, the mounting accuracy affects the yield and deteriorates the manufacturing cost.

Therefore, it is an object of the present invention to provide a shield substrate which facilitates the shield treatment and enhances the shield effect.

[0007]

As shown in FIG. 2, the shield substrate of the present invention surrounds the circuit pattern (4) of the circuit substrate (2) to be shielded with a shield member (shield case 16). At the same time, the ground pattern (8) electrically connected to the ground pattern portion (9) of the circuit pattern, and the positioning frame (12A, 12B) of the shield member formed along the ground pattern.
And a shield member fixed by a fixing member (conductive adhesive 18) installed in the positioning frame to shield the circuit pattern.

[0008]

In this shield board, a ground pattern is formed at a position surrounding the circuit pattern on the circuit board, and the ground pattern and the ground pattern portion on the circuit pattern side are electrically connected, and the shield member is provided along the ground pattern. A positioning frame for fixing is formed, a shield member is installed on the basis of this positioning frame and fixed with a fixing member, and the ground pattern is electrically connected. In such a shield structure, a desired circuit pattern can be wholly or partially surrounded by a ground pattern, and the shield member can shield the circuit pattern.

The ground pattern surrounding the circuit pattern and the shield member for concealing the circuit pattern are electrically connected, and the shield member and the ground pattern reliably shield the circuit pattern entirely or partially. It is possible to obtain a highly reliable shield effect. Moreover, since the positioning frame is installed to position the shield member, the mounting position is highly accurate and the shield reliability can be improved.

In particular, since the ground pattern portion on the circuit pattern side is electrically connected to the ground pattern on the positioning frame, the ground point on the circuit pattern side and the shield can be set to the same potential, and the shield effect is improved. To be enhanced.

[0011]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIGS. 1A, 1B and 2 show one embodiment of the shield substrate of the present invention, and FIG. 2 shows a part of the shield substrate shown in FIG. An insulating substrate such as a ceramic substrate is used as the circuit board 2, and an arbitrary circuit pattern 4 is formed on the surface thereof. A plurality of circuit components 6 such as capacitors, resistors and transistors are mounted on the circuit pattern 4.

The circuit pattern 4 is formed on the circuit board 2.
A ground pattern 8 is formed at a position surrounding the. In this case, the ground pattern portion 9 on the circuit pattern 4 side is printed and fired in advance at the position where the ground pattern 8 is to be formed, and the ground pattern 8 is formed thereon. This ground pattern 8 is similar to the conductive layer forming the circuit pattern 4 in that it is made of Ag.
It is formed by printing a system conductive paste or the like and firing it. The ground pattern 8 and the ground pattern portion 9 are electrically connected by superposition of both. In this embodiment, a plurality of conductor layers 10 for connecting lead terminals are formed on the edge of the circuit board 2.

Positioning frames 12A, 12B are formed on the surface of the circuit board 2 so as to surround the ground pattern 8 and indicate the mounting positions of the shield members. Each positioning frame 12A, 12B is formed in an annular shape by lamination printing of insulating paste or the like, and a constant space 14 is formed between each positioning frame 12A, 12B. For example, a thick film dielectric paste is used for the positioning frames 12A and 12B, and the height is set to an appropriate height by multiple printing and two or more printing processes. For example, the height is formed to be 40 μm or more. The space 14 forms a space for fixing the shield case 16 as a shield member and holding the conductive adhesive 18 as a fixing member for fixing the shield case 16.

The shield case 16 is formed by molding a metal plate having good conductivity, and its opening area corresponds to the annular portion formed by the space 14 between the positioning frames 12A and 12B. The shield case 16 is fixed inside the space 14, that is, by the conductive adhesive 18 loaded inside the shield case 16, and is electrically connected to the ground pattern 8. In this case, the positioning frame 1
2A and 12B have a volume within the space 14 to prevent the conductive adhesive 18 from squeezing out to the outside and to retain a surplus.

Next, FIG. 3 shows positioning frames 12A and 12B.
7 shows the treatment of the conductive adhesive 18 with respect to. The positioning frames 12A and 12B are formed by printing and firing an insulating paste, and a ground pattern 8 is formed inside the space 14. In the ground pattern 8, the ground pattern on the circuit pattern 4 side is positioned. 12A, 12B
Are electrically connected to each other within the space 14 of.
As a result, the grounding point of the circuit pattern 4, the grounding pattern 8 and the shield case 16 are set to the same potential, so that a reliable shield effect is obtained.

Then, as a means for supplying the conductive adhesive 18 into the space 14 between the positioning frames 12A and 12B, for example, a dispenser 20 is used to pour the conductive adhesive 18 and then the shield case 16 is installed and pushed. The shield case 16 is fixed and electrically connected to the ground pattern 8 by being dried and cured by.

Next, FIG. 4 shows another embodiment of the shield substrate of the present invention. In the above-described embodiment, the conductive adhesive 18 is filled inside the shield case 16, but the conductive adhesive 18 may be installed outside the shield case 16. Further, in the above embodiment, the ground pattern portion 9 is extended to the outside of the positioning frame 12A, but as shown in FIG. 4, it is installed inside the positioning frame 12A, that is, inside the space 14. Good.

In the embodiment, a conductive adhesive is used as the fixing member, but if the electrical connection is made with solder or the like,
An insulating adhesive may be used. You may use solder as a fixing member.

[0020]

As described above, according to the present invention,
The circuit pattern on the circuit board can be wholly or partially shielded, and the processing can be simplified, and the ground pattern and the shield member and the ground pattern portion on the circuit pattern side can be electrically connected. Since the connection is made, a highly reliable shield effect can be realized.

[Brief description of drawings]

FIG. 1 shows an embodiment of a shield substrate of the present invention,
(A) is the top view, (B) is the BB sectional view taken on the line of (A).

FIG. 2 is a cross-sectional view showing a part of the shield substrate shown in FIG.

FIG. 3 is a perspective view showing an embodiment of a method for treating the shield substrate shown in FIG.

FIG. 4 is a sectional view showing another embodiment of the shield substrate of the present invention.

[Explanation of symbols]

 2 circuit board 4 circuit pattern 8 ground pattern 9 ground pattern part 12A, 12B positioning frame 16 shield case (shield member) 18 conductive adhesive (fixing member)

Claims (1)

[Claims] 1. A ground pattern which surrounds a circuit pattern of a circuit board to be shielded with a shield member and is electrically connected to a ground pattern portion of the circuit pattern, and the ground pattern formed along the ground pattern. A shield substrate, comprising: a positioning frame for the shield member; and a shield member fixed by a fixing member installed in the positioning frame to shield the circuit pattern.