JPH07142832A - Printed board and electronic circuit employing the same - Google Patents

Abstract

PURPOSE:To discharge heat with a simple construction when a heating value is relatively small by a method wherein the part of a metal layer on which a heating component is mounted is exposed by cutting off the part of another layer on the metal layer. CONSTITUTION:A printed board has a multilayer structure and one metal layer 2 of its inner layers is so provided as to spread at least over a whole part where radio frequency circuits are formed. The metal layer 2 is connected to a ground potential. The part of another layer on the metal layer 2 is removed so as to expose the part of the metal layer 2 on which a heating component is mounted. In an electronic circuit using a printed board like this, the heating component is mounted on the part of the metal layer 2 of a heating component mounting section 7 from which the part of the surface layer is removed so as to have its case brought into direct contact with the metal layer 2. Therefore, the heat generated by the heating component is transferred over the whole area of the metal layer 2 and the transferred heat is further transferred to a housing through a plurality of attaching screws with which the printed board 1 is fixed and is discharged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a printed circuit board on which an electronic circuit is mounted. The present invention was developed especially for use in an environment where heat dissipation conditions are bad, such as a space environment, but can be widely used as an electronic circuit and its printed circuit board.

[0002]

2. Description of the Related Art A conventional heat dissipation structure for a printed circuit board 11 is
As shown in FIGS. 4A and 4B, a heat dissipation plate 12 is used to transfer the heat generated from the heat generating component 5 to the mounting screw 4 and radiate the heat from the mounting screw 4 to the housing 6. .

Further, conventionally, as a printed circuit board for mounting a high frequency circuit, a multilayer substrate is used and one metal layer of an inner layer is formed into a solid pattern, and the solid pattern is connected to a ground potential to form the solid pattern. There is known a technique of forming a circuit pattern on the surface layer via an insulating layer at different positions. In such a circuit, a strip line can be formed so that the circuit pattern formed on the surface layer has a certain characteristic impedance between itself and the metal layer as the inner layer, or the metal layer is shielded by a shield layer. It can be used as In this specification, such a circuit is simply referred to as a "high-frequency circuit", which means a circuit that handles a signal of a frequency that forms the characteristic impedance as described above or that needs a shielding effect.

On the other hand, it is often necessary to attach a heating element such as a semiconductor element having a large power capacity to the printed circuit board. As a conventional technique in such a case,
There is a technique disclosed in Japanese Utility Model Publication No. 59-35021 or a technique disclosed in Japanese Utility Model Publication No. 60-92861. Each of these has a structure in which a heating element mounted on a printed circuit board is thermally connected to a housing in which the printed circuit board is mounted.

[0005]

In such a heat dissipation structure, the degree of freedom in circuit design is lost because the layout of the printed circuit board is extremely restricted. Also, the number of manufacturing and assembling steps increases, and the device price increases.

On the other hand, in an electronic circuit used in the space environment in which the inventor is involved, the air around the printed circuit board or the electronic circuit may be diluted, and heat dissipation due to convection may be almost impossible. In such a case, even if the element has a small amount of heat generation, it must be designed so that heat is dissipated by radiation or conduction. The structure may be too large for such a thermal design with the above structure.

The present invention has been made against such a background, and an object thereof is to provide a printed circuit board and an electronic circuit which can dissipate heat with a simple structure when the calorific value is relatively small. To do.

[0008]

The inventor of the present invention has paid attention to the use of a metal layer, which is an inner layer of a printed circuit board, which is connected to the ground potential and spreads over almost the entire circuit, for heat dissipation, as described above.

That is, according to the present invention, in a printed circuit board having a multi-layer structure, one metal layer of the inner layer is formed so as to spread over at least the entire portion where the high frequency circuit is formed, and the metal layer is connected to the ground potential. The other layer is cut off so that the metal layer appears on the surface at the position where the heat generating component is mounted.

As an invention related to the present invention, the actual Kaihei 2-1.
There is a technique disclosed in Japanese Patent No. 7891, which uses a metal layer on the surface of a printed circuit board, which is originally to be removed along with the formation of a circuit pattern, for utilizing in heat dissipation. This is a technique that leaves some of them without removing them. This is because the present invention increases the degree of freedom in circuit design as compared with the present invention, whereas this prior art restricts the degree of freedom in circuit design.

Another aspect of the present invention is an electronic circuit using this printed circuit board, comprising a printed circuit board having a multi-layer structure, and one metal layer of the inner layer of the printed circuit board is at least a part where a high frequency circuit is formed. It is formed so as to spread all over, the metal layer is connected to the ground potential, a part of the surface of the printed circuit board is cut off, and the heat generating component is attached so as to be in thermal contact with the metal layer. And

[0012]

Since the heat-generating component is mounted on the metal layer where the other layers of the printed circuit board are cut off, the heat generated by the heat-generating component is directly transferred to the metal layer, and the heat transmitted to this metal layer is transferred to the plurality of mounting screws. The heat is dispersed and dissipated in the housing that fixes the printed circuit board. As a result, it is possible to prevent the heat generated by the heat-generating component from being accumulated due to the promotion of heat dissipation, and further, since the heat radiation plate or the heat radiation fin that has been used conventionally is not necessary, the number of components can be reduced, Manufacturing cost and manufacturing man-hours can be reduced.

[0013]

Embodiments of the present invention will now be described with reference to the drawings.

(First Embodiment) FIG. 1 (a) is a plan view showing the structure of the first embodiment of the present invention, (b) is a side view thereof, and FIG. 2 is a mounting of heat-generating components in the first embodiment of the present invention. It is a side view which shows an example.

The first embodiment of the present invention has a multi-layer structure in which one metal layer 2 of the inner layer is formed so as to spread over at least the entire portion where the high frequency circuit is formed.
Is connected to the ground potential, and the other layer is cut off so that the metal layer 2 appears on the surface at the position where the heat generating component 5 is mounted. As shown in FIG. 2, the electronic circuit using the printed circuit board 1 configured as described above has the case of the heat-generating component 5 directly mounted on the metal layer 2 of the heat-generating component mounting portion 7 whose surface is partially cut off. It is attached so that it touches.

Therefore, the heat generated from the heat-generating component 5 is transferred to the entire area of the metal layer 2, and the transferred heat is transferred from the plurality of mounting screws 4 to which the printed circuit board 1 is mounted to the housing 6.
It is transmitted to and is radiated. Since the degree of heat radiation depends on the thermal resistance of the metal layer 2, the effect can be further improved by adjusting the plating thickness applied to the metal layer 2 according to the degree of heat generation.

The multilayer printed circuit board according to the present invention comprises:
The effect is great when heat dissipation due to convection is hardly obtained, such as in a space environment.

(Second Embodiment) FIG. 3 is a side view showing an example of mounting heat generating components in a second embodiment of the present invention.

The second embodiment of the present invention is applied when the heat-generating component 5 is not grounded to the collector, and has high heat conductivity and electrical insulation between the case of the heat-generating component 5 and the metal layer 2. A sheet 8 having a groove is interposed. Sheet 8 in this case
Has heat conductivity, the heat generated by the heat-generating component 5 is transferred from the sheet 8 to the metal layer 2 and is radiated as in the first embodiment.

[0020]

As described above, according to the present invention, by exposing a part of the metal layer and adjusting the plating thickness, the heat generated by the heat-generating component can be efficiently transmitted to the entire metal layer. This can be radiated to the housing, and there is an effect that it can be prevented from being accumulated in the heat generating component.

Particularly, it is effective in the case of a structure such as outer space where there is no convection and heat is dissipated only by conduction of heat.
Since the heat dissipation plate or the heat dissipation fin is not necessary, the number of parts can be reduced and the number of manufacturing steps can be reduced.

[Brief description of drawings]

1A is a plan view showing the configuration of a first embodiment of the present invention, and FIG. 1B is a side view thereof.

FIG. 2 is a side view showing an example of mounting heat generating components in the first embodiment of the present invention.

FIG. 3 is a side view showing an example of mounting heat generating components in the second embodiment of the present invention.

4A is a plan view showing a mounting example of a heat-generating component in a conventional example, and FIG. 4B is a side view thereof.

[Explanation of symbols]

 1, 11 Printed circuit board 2 Metal layer 3 Mounting hole 4 Mounting screw 5 Heat generating component 6 Housing 7 Heat generating component mounting part (dissected part) 8 Sheet 12 Heat sink

Claims (5)

[Claims] 1. A printed circuit board having a multi-layered structure, one metal layer of the inner layer of which is spread over at least the entire portion where a high-frequency circuit is formed, and the metal layer is connected to a ground potential. A printed circuit board, wherein another layer is cut off so that the metal layer appears on the surface at the position where the is mounted. 2. A printed circuit board having a multi-layer structure, wherein one metal layer of an inner layer of the printed circuit board is formed so as to extend to at least the entire portion where a high frequency circuit is formed, and the metal layer is connected to a ground potential. An electronic circuit characterized in that a part of the surface of the printed circuit board is cut off and a heat generating component is attached to the metal layer so as to be in thermal contact. 3. The electronic circuit according to claim 2, wherein the case of the heat generating component is attached so as to directly contact the metal layer. 4. The electronic circuit according to claim 2, wherein the case of the heat-generating component is attached so as to be in contact with the metal layer via an electrically insulating material having high thermal conductivity. 5. The electronic circuit according to claim 2, wherein the metal layer is thermally and electrically connected to a housing in which the electronic circuit is mounted, via a metal mounting member.