JPH0653686A - Shield film - Google Patents

Abstract

PURPOSE:To obtain a shield film having a simple handling and small special- purpose space by incorporating thermal shrinkage in an insulating layer and a conductive thin film layer. CONSTITUTION:A shielding member for forming an electromagnetic shield of an electronic circuit comprises at least one of conductive thin film layer 3, and a pair of insulating layers 1, 2 so formed on an upper layer and a lower layer as not to expose the layer 3 with the surface. The layers 1, 2 and the layer 3 have thermal shrinkage. Accordingly, a film has flexibility at an initial state and can simply enclose a desired electronic circuit or its part. When the layers 1, 2 are heated to a temperature to be shrinked in this state, the film is shrunk to be brought into close contact with the circuit. In this case, since the layers 1, 2 are brought into contact with the circuit, no short-circuit occurs by the layer 3 in the circuit.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a shield film. More specifically, the present invention relates to a novel shield member structure that can be widely and conveniently used in electronic devices that require electromagnetic shielding.

[0002]

2. Description of the Related Art In general, an electronic circuit in operation emits electromagnetic waves to the outside, in addition to its original function. In addition, when an electromagnetic wave from the outside is received, noise may be generated in the signal path of the device itself, or in the extreme case, malfunction may occur. For this reason, in many electronic circuits, a predetermined unit or the entire device is covered with a shield member having an electromagnetic shielding function to reduce mutual influence of electromagnetic waves. In practice, such shields are, in most cases, configured as metallic cases or covers that house specific electronic circuits.

[0003]

However, with respect to the recent miniaturization of electronic circuits, the conventional shield member as described above occupies a large space in three dimensions, and is extremely disadvantageous in terms of space factor. . Further, since the electronic circuit is designed and manufactured in accordance with the shape of the electronic circuit to be shielded, the productivity is extremely low.

Therefore, an object of the present invention is to provide a novel shield member which is easy to handle and has a small occupied space.

[0005]

According to the present invention, there is provided a shield member for forming an electromagnetic shield for an electronic circuit, comprising:
An electrically conductive thin film layer having at least one conductive layer; and a pair of insulating layers formed above and below the conductive thin film layer so that the conductive thin film layer is not exposed to the surface. There is provided a shield film, wherein the layer and the conductive thin film layer have heat shrinkability.

[0006]

The shield film according to the present invention is characterized in that it is formed by laminating a conductive thin film layer directly involved in an electromagnetic shielding function and a heat-shrinkable insulating layer which facilitates mounting on an electronic circuit. There are major features.

That is, the shield film according to the present invention is
The film is flexible in the initial state and can easily wrap a desired electronic circuit or a part thereof. In this state, when the insulating layer is heated to a temperature at which it contracts, the film contracts and adheres to the electronic circuit. At this time, since the insulating layer is in direct contact with the electronic circuit, the conductive thin film layer does not cause a short circuit in the electronic circuit. The heating temperature depends on the rubber material used,
The degree is enough, and in fact it is enough to blow the warm air of the hand dryer.

Further, according to one aspect of the present invention, the shield film according to the present invention can be manufactured in a tubular shape to further simplify the handling. That is, a heat-shrinkable film generally shrinks in the plane direction when heated. Therefore, in order to prevent the shield film from falling off the electronic circuit to be electromagnetically shielded,
As will be specifically described below, it is necessary to devise the shape of the shield film or devise a heating method for heat-shrinking the shield film.

In the shield film according to the present invention, the conductive thin film layer can be formed by mixing a conductive material such as carbon with the material forming the insulating layer. Here, the conductive thin film layer and the insulating layer,
By forming them basically from the same material, the affinity between them can be improved and the heat shrinkability can be obtained in common to both. The conductive thin film layer having such a thickness can be formed on the surface of the resin film to be the insulating layer by various known methods.

Hereinafter, the present invention will be described in more detail with reference to examples, but the following disclosure is merely an example of the present invention and does not limit the technical scope of the present invention.

[0011]

EXAMPLE FIG. 1 is a view showing the basic structure of a shield film according to the present invention.

As shown in the figure, the shield film is composed of a pair of insulating layers 1 and 2 and a conductive thin film 3 sandwiched between the insulating layers.

Such a shield film can be manufactured as follows. FIG. 2 is a diagram for explaining one of the methods for manufacturing the above-mentioned shield film.

First, as shown in FIG. 2 (a), an insulating film to be the insulating layer 1 is prepared as a base. The insulating film used here is an insulating film having a thickness of about 400 μm, and preferable examples thereof include polyethylene rubber.

Next, as shown in FIG. 2 (b), a conductive thin film mixed with carbon is loaded on the insulating film, and subsequently, as shown in FIG. 2 (c), the conductive thin film layer is formed. An insulating film to be the second insulating layer is loaded on the insulating layer loaded with. After that, heat is uniformly applied to the three layers to perform pressure bonding, and then the layers are formed into a tube shape or a film shape.

Through the above steps, the shield film as shown in FIG. 1 can be manufactured.

Incidentally, the shield film according to the present invention can be prepared by other methods than the pressure bonding method as described above.

FIG. 3 is a diagram showing an embodiment of the shield film having a laminated structure according to the present invention as described above.

As shown in FIG. 3 (a), in this embodiment, the shield film 10 has a tubular shape. Here, the inner diameter of the cylinder formed by the shield film 10 has a size enough to accommodate the electronic circuit to be finally electromagnetically shielded. When the electronic circuit 11 is housed in the shield film 10 having such a shape and then heated, the shield film 10 contracts and substantially adheres to the electronic circuit 11 as shown in FIG. 3B. Therefore, the shield film 10 will not fall off the electronic circuit 11.
In addition, even after the shield film 10 is attached, the overall size is almost the same as that of the electronic circuit 11 alone, so that the size of the electronic circuit as a whole is smaller than that of the conventional electronic circuit including the shield member. Furthermore, after the connection to the electronic circuit 11 is completed, the opening of the tubular shield film is sealed to protect the entire electronic circuit 11 from dust and water vapor.

FIG. 4 is a view showing another embodiment of the shield film according to the present invention as described above.

The shield film 12 shown in FIG. 4 (a) is a substantially plate-shaped flat film. As shown in the figure, this shield film should be wrapped around the lower side of the electronic circuit 11.
After mounting 12, the shield film 12 is heated only from the lower side of the electronic circuit 11. In this case, as shown in Fig. 4 (b),
Since the shield film 12 contracts at the portion around the lower side of the substrate and its vicinity, it does not fall off from the electronic circuit 11. Further, in this embodiment, since the lower surface of the electronic circuit 11 is almost opened, it is possible to connect the lower surface of the substrate to other members even after the shield film 12 is attached.

In this embodiment, the shield film is a flat plate-shaped member. However, if the shield film is formed into a cap shape or a cup shape in advance, it is easy to position and hold the film before heating. Further, the heating may be performed not only on the lower surface but also on the peripheral portion of the electronic circuit 11.

FIG. 5 is a view showing still another embodiment of the shield film according to the present invention.

As shown in the figure, this shield film
13 has a tubular or bag-like shape with at least one opening. Further, the size is shorter than the electronic circuit 11 to be mounted, and is configured so as to surround only the left half of the electronic circuit 11 in the drawing.

In the above-described embodiment, the vicinity of the opening of the shield film 13 is folded back as shown in the figure so that the electronic circuit is not short-circuited by the conductive thin film layer exposed on the end surface of the shield film 13. It is preferable to heat-shrink.

[0026]

As described above, the shield film according to the present invention is extremely easy to handle, and the electromagnetic shield can be easily formed on any electronic circuit.

Further, since the shield film according to the present invention comes into close contact with the electronic circuit after the heat shrinkage, almost no space is required for the shield itself.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of a shield film according to the present invention.

FIG. 2 is a diagram for explaining an example of the method of manufacturing the shield film of the present invention.

FIG. 3 is a view showing one embodiment and usage of the shield film of the present invention.

FIG. 4 is a diagram showing another embodiment and usage of the shield film of the present invention.

FIG. 5 is a view showing still another embodiment of the shield film according to the present invention.

[Explanation of symbols]

 1, 2 ... Insulating layer, 3 ... Conductive thin film layer, 10, 12 ... Shield film, 11 ... Electronic circuit

Claims (6)

[Claims] 1. A shield member for forming an electromagnetic shield of an electronic circuit, comprising at least one conductive thin film layer having conductivity and the conductive thin film layer so as not to be exposed on the surface. A shield film comprising: a pair of insulating layers formed on an upper layer and a lower layer of a thin film layer, wherein the insulating layer and the conductive thin film layer have heat shrinkability. 2. The shield film according to claim 1, wherein the insulating layer is made of polyethylene rubber. 3. The shield film according to claim 1 or 2, wherein the conductive thin film layer is formed of carbon rubber-containing polyethylene rubber. 4. The shield film according to any one of claims 1 to 3, which has a tubular shape as a whole. 5. The shield film according to any one of claims 1 to 3, which can be mounted so as to wrap around from the front surface to the back surface of an electronic circuit to be electromagnetically shielded, A shield film having a dimension such that it does not fall off from the electronic circuit by heating a portion that has wrapped around the back surface. 6. The shield film according to any one of claims 1 to 3, which has a tubular or bag-like shape and can surround only a part of one electronic circuit. A shield film that is formed in various dimensions.