JP2002327154A - Conductive double sided tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light weighed and thin conductive double sided tape equipped with both sufficient adhesive property and electric conductive property and also having a good working property. SOLUTION: This conductive double sided tape is obtained by using a nonwoven fabric having an electric conductivity, a sufficiently thin thickness in a level of approximately 0.1 mm thickness, 10-15 g/m<2> unit weight and a relatively large gap between fibers 11a, forming a base substrate layer by applying an adhesive on such nonwoven fabric 11 and arranging an electric conductive filler 20 by falling or blowing it for spreading on the both sides of the base substrate. The conductive filler is made as a circular metal foil having 0.1-0.5 mm diameter which is 2-200 fold of the diameter of the fiber 11a of the nonwoven fabric 11, and its amount is decided by considering the relationship of its areal ratio occupying the base substrate layer, an adhesive property and an electric conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided conductive tape capable of establishing conduction between both adhesive surfaces.

[0002]

2. Description of the Related Art For example, when a gasket for shielding electromagnetic waves is attached to an opening / closing portion of a metal case, a conductive double-sided tape is sometimes used. The conductive double-sided tape is required to have an adhesive property for fixing the gasket to the metal case and a conductive property for achieving conduction between the metal case and the conductive member. At this time, since the surface of the gasket may be made of a conductive cloth, it is preferable that the gasket has a sufficient adhesive property and is not easily peeled off even if the surface has some irregularities. Furthermore, in consideration of not only the adhesive performance and the conductive performance but also the efficiency of the sticking operation by the operator, a material having good workability is desired.

Conventional double-sided conductive tapes are composed of two types: an adhesive layer in which a conductive filler is dispersed, laminated on both sides of a metal foil serving as a base material, and a tape consisting only of an adhesive layer in which a conductive filler is dispersed. Are roughly divided into

[0004]

However, the above-mentioned conventional conductive double-sided tape has the following disadvantages. The former, that is, a tape having a metal foil as a base material, lacks flexibility, particularly when adhered to, for example, a conductive cloth having irregularities on the surface. I will. Of course, the adhesive performance can be improved by increasing the thickness of the adhesive layer, but in this case, the conductive performance deteriorates. Further, when the metal foil as the base material is thinned to secure flexibility, the possibility that the adhesive layer is peeled off due to deformation of the metal foil increases.

[0005] On the other hand, the latter, ie, a tape comprising only an adhesive layer, has a high flexibility and high adhesive performance because there is no base layer, but on the other hand, the tape itself tends to elongate, and workability is extremely poor. Further, when the tape is stretched, the density of the conductive filler in the pressure-sensitive adhesive layer becomes low, so that the conductive performance may be impaired.

Further, recently, as electronic devices have become smaller and lighter, the above-mentioned conductive double-sided tape has also been required to be lighter and thinner. The present invention has been made to solve such a problem, and provides a light and thin conductive double-sided tape that is a conductive double-sided tape that has both sufficient adhesive performance and conductive performance and has good workability. The purpose is to do.

[0007]

Means for Solving the Problems and Effects of the Invention The conductive double-sided tape according to the first aspect of the present invention, which has been made to achieve the above object, includes a base material layer and a conductive filler.
The base material layer is formed into a sheet by applying a pressure-sensitive adhesive to a nonwoven fabric or a woven fabric having conductive properties. As this cloth material, a material having a sufficiently small thickness of, for example, about 0.1 mm and having a relatively large gap between fibers is used. Then, conductive fillers are dispersed and arranged on both side surfaces thereof. The conductive filler is
For example, it is fixed to the base material layer by the action of an adhesive applied to the cloth material by appropriately sowing the base material layer or spraying the base material layer.

That is, by using a sufficiently thin cloth material, the flexibility of the base layer is ensured, so that even if the surface has some irregularities such as a conductive cloth, the followability to the irregularities is ensured. And sufficient adhesive performance is exhibited. Moreover, since the adhesive enters the relatively large gap between the fibers, it is possible to prevent the adhesive from peeling off from the cloth material. Conversely, the thickness of the cloth material and the gap between the fibers are determined in consideration of followability and prevention of peeling of the adhesive. In addition, since there is a base material layer, the tape itself does not stretch and workability is good.

On the other hand, the conductive performance varies depending on the probability of contact between the fibers of the cloth material and the conductive filler. This is because conduction cannot be achieved by the conductive fillers disposed in the gaps between the fibers described above. However, simply increasing the amount of the conductive filler undesirably increases the weight of the tape. Further, even if the ratio of the area occupied by the conductive filler per unit area of the base material layer becomes too large, the exposed portion of the pressure-sensitive adhesive decreases, and conversely, the pressure-sensitive adhesive performance decreases.

Therefore, in the present invention, the conductive filler crushed in the shape of a flake is used, and the ratio of the area occupied by the conductive filler per unit area of the base material layer becomes an appropriate ratio in consideration of the adhesive performance and the conductive performance. I made it. The appropriate ratio here depends on the ratio of the area occupied by the fibers of the cloth material to the base material layer. However, when the area ratio of the fibers is about 5 to 10% of the whole, the appropriate amount of the conductive filler The area ratio becomes about 3 to 45%. In addition, it is preferable to set it to about 5 to 15%.

That is, by using the flaky conductive filler, the probability of contact with the fiber of the cloth material is increased, and such an appropriate ratio can be achieved by using a small amount of the conductive filler. As a result, sufficient conductive performance can be ensured together with the adhesive performance, and the entire tape can be made thinner and lighter than when a granular conductive filler is used.

For example, if the conductive filler is realized by a metal foil piece having a thickness of about 0.1 μm,
Compared to the same weight of granular conductive filler, the area is 20
It becomes 00-3000 times. Therefore, if a metal foil piece is used, the present tape becomes extremely thin and extremely light.

This technical idea is to adjust the contact probability between the dispersed conductive filler and the cloth material by devising the shape, and it may be realized by the configuration described in claim 3. That is, using a cloth material composed of wide fibers crushed in one direction, so that the ratio of the fibers per unit area of the base material layer is an appropriate ratio in consideration of the adhesive performance and the conductive performance. It was done. In this case, the contact probability is adjusted by increasing the width of the fiber of the cloth material. Since the fibers of the cloth material are crushed, the base material layer becomes thin, and as a result, the present tape can be made thin. In addition, the area ratio of the fiber of the cloth material can be considered in the same manner as in the above-described configuration. For example, when the area ratio of the conductive filler is about 5 to 10% of the whole, the appropriate area ratio of the fiber is 3%.
About 45%. In addition, it is preferable to make it about 5 to 15%.

Further, when a cloth material composed of wide fibers crushed in one direction is used together with the flaky conductive filler, the present conductive double-sided tape is reduced in weight and thickness. That is, the effect described above is even more prominent. By the way, although it has already been described that the base material layer is formed by applying an adhesive to the cloth material, if the adhesive is applied more than necessary to both sides of the cloth material, the conductive filler may contact the cloth material. And the conductive performance may be reduced.

Therefore, as described in claim 5, it is preferable to remove the excess adhesive on both sides of the cloth material and dispose the conductive filler. At this time, prior to the application of the adhesive, a removing agent for facilitating the removal of the adhesive is applied to the base material layer in order to remove the excess adhesive on both sides of the cloth material. It is conceivable to apply it to It is conceivable to use, for example, a fluorine-based resin as the removing agent. By doing so, the adhesive enters between the fibers of the cloth material, and excess adhesive on the surface is removed, so that the probability of contact between the conductive filler and the cloth material is increased, and conduction performance is ensured.

From the viewpoint of improving the conduction performance, it is conceivable that plating is applied to the cloth material constituting the base material layer. When the cloth material itself such as a carbon nonwoven fabric or a woven fabric has a conductive property, the conductive property can be further improved by such plating.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is an explanatory diagram illustrating a conductive double-sided tape 1 according to an embodiment. The conductive double-sided tape 1 includes a base layer 10 and a conductive filler 20.

The base material layer 10 is formed by applying a pressure-sensitive adhesive 12 to both sides of a nonwoven fabric 11 as a cloth material having conductive properties, and is formed in a sheet shape. Conductive filler 20
Are dispersed and arranged on both side surfaces of the base material layer 10, and the adhesive 12 applied to the nonwoven fabric 11 causes the base material layer 10
It is fixed to. FIG. 1A illustrates one side surface.

Such a double-sided conductive tape 1 is formed as follows. The non-woven fabric 11 is made of carbon fiber non-woven fabric, having a thickness of about 0.1 mm and a basis weight of 10 to 15 g.
/ M ² . That is, a material that is sufficiently thin and has a relatively large gap between fibers is used. A metal coating of about 100 to 300 Å is further formed on such a nonwoven fabric 11 by sputtering. In this embodiment, the carbon fiber non-woven fabric is used. However, for example, a non-conductive non-woven fabric may be plated with metal.

Next, a fluorine-based spray is sprayed on both side surfaces of the nonwoven fabric 11. This is for facilitating removal of excess adhesive 12 after application of adhesive 12 as described later. After that, the adhesive 12 is applied. The pressure-sensitive adhesive 12 may be of an acrylic type, a silicone type, a synthetic rubber type, or the like. At this time, the adhesive 12 penetrates into the gaps between the fibers of the nonwoven fabric, and then the excess adhesive 12 on the surface is removed. After removing the excess adhesive 12, sow the conductive filler 20, or
It is arranged so as to be spread on both sides of the base material layer 10 by spraying. The conductive filler 20 includes nickel-based,
A general metal such as copper or silver is used. Note that carbon fiber may be used.

Finally, release papers are attached to both sides of the conductive double-sided tape 1. This release paper is for protecting the adhesive surface, and is peeled off during operation. As shown in FIG. 1 (b), the conductive double-sided tape 1 of this embodiment is used, for example, for attaching a gasket whose sponge surface is covered with a conductive cloth to, for example, an opening / closing portion of a metal case. Therefore, the conductive double-sided tape 1 is required to have sufficient adhesiveness and conductive performance and good workability. Further, it is desirable to reduce the thickness and the weight.

On the other hand, as described above, the conductive double-sided tape 1 is rich in flexibility because it uses the nonwoven fabric 11 which is sufficiently thin, has good followability to irregularities on the surface of the conductive cloth, and has a sufficient property. Demonstrates adhesive performance. Further, since the adhesive 12 applied to the nonwoven fabric 11 enters the gap between the fibers, even if the nonwoven fabric 11 is deformed, the adhesive 12 does not peel off. And since there is the base material layer 10 comprised of the nonwoven fabric 11, good workability is also ensured.

In the present embodiment, in particular, the following measures were taken to ensure sufficient conductive performance while securing adhesiveness, and furthermore, the tape itself was thinned to reduce its weight. That is, the flaky conductive filler 20 was used, and the area ratio of the conductive filler 20 to the base material layer 10 was increased with a relatively small amount of the conductive filler 20. As shown in FIG. 2, a circular metal foil piece having a diameter of about 0.1 to 0.5 mm, which is 2 to 200 times the diameter of the fiber 11 a of the nonwoven fabric 11, is used as the conductive filler 20.
For example, if a metal foil piece having a thickness of about 0.1 μm is used, the area becomes 2000 to 3000 times even with the same weight.

However, if the area ratio is increased, the conductive performance is secured, but the adhesive performance is reduced. FIG. 3 shows that the conductive performance and the adhesive performance are different from those of the base material layer 10 of the conductive filler 20.
FIG. 9 is a model diagram showing how the area ratio changes according to the area ratio. In FIG. 3, the conductive performance is shown by a dashed line, and the adhesive performance is shown by a solid line.

In FIG. 3, the conductive performance rapidly rises when the area ratio occupied by the conductive filler 20 increases from 0%, and becomes almost the maximum when the area ratio exceeds 50%.
After that, it gradually rises. On the other hand, the adhesive performance decreases at a substantially constant rate as the area ratio of the conductive filler 20 increases. The reason is that the larger the proportion of the area occupied by the conductive filler 20, the smaller the exposed area of the adhesive 12.

Therefore, in this embodiment, the amount of the conductive filler 20 is adjusted in consideration of the conductive performance and the adhesive performance. In FIG. 3, it is conceivable to make adjustments so as to be within the range indicated by the symbol β in which the conductive performance and the adhesive performance are sufficiently ensured. More preferably, the adjustment is performed so as to be within the range indicated by the symbol α. The graph shown in FIG. 3 changes depending on the diameter and amount of the fiber 11a of the nonwoven fabric 11, for example,
The area ratio of the fibers 12a of the nonwoven fabric 11 is 5 to 10% of the whole
If so, the range indicated by the symbol β is in the range of about 3 to 45%, while the range indicated by the symbol α is in the range of about 5 to 15%.

As described above, in this embodiment, the flaky conductive filler 20 is used, and a relatively small amount of the conductive filler 2 is used.
0, the area ratio of the conductive filler 20 to the base material layer 10 was adjusted. Thereby, the adhesive performance and the conductive performance are ensured, and the conductive double-sided tape 1 is light,
Become thin.

In this embodiment, the conductive filler 20 is disposed by removing the excess adhesive 12 on the surface of the non-woven fabric 11, and the non-woven fabric 11 is made of carbon fiber non-woven fabric, The conductive performance is also improved because the metal film is formed on the surface. Further, a fluorine spray is used prior to the application of the adhesive 12. This facilitates the work of removing the adhesive 12.

As described above, the present invention is not limited to such an embodiment, and can be implemented in various forms without departing from the gist of the present invention. For example, FIG.
As shown in (a), a nonwoven fabric 31 composed of linear fibers 31a may be used. That is, it is only necessary that the fiber is sufficiently thin and the gap between the fibers is relatively large, and the shape of the fiber may be any. Therefore, it is possible to use not only a nonwoven fabric but also a woven fabric.

Further, as shown in FIG. 4B, the same non-woven fabric 51
Of the fibers 51a may be widened and crushed in one direction. In FIG. 4B, the nonwoven fabric 51 is formed by strip-shaped fibers 51a. Also in this case, similarly to the above-described embodiment, the contact probability between the conductive filler 40 and the nonwoven fabric 51 can be improved, and the nonwoven fabric 51 can be made thinner and the amount of the conductive filler 40 can be suppressed. The tape itself can be made thinner and lighter while ensuring the performance and conductive performance.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a conductive double-sided tape of an example.

FIG. 2 is a model diagram showing a nonwoven fabric and a conductive filler.

FIG. 3 is a model diagram showing a relationship between an area ratio of a conductive filler and adhesive performance / conductive performance.

FIG. 4 is a model diagram showing a nonwoven fabric and a conductive filler of another example.

[Description of Signs] 1 ... Conductive double-sided tape 10 ... Base layer 11, 31, 51 ... Non-woven fabric 11a, 31a, 51a ... Fiber 12 ... Adhesive 20, 40 ... Conductive filler

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J004 AA05 AA10 AA11 AA18 CB01 DB02 EA05 FA05 4J040 CA001 DF001 EK001 HA036 HA066 JA09 JB09 JB10 KA01 KA42 LA09 NA19 PA23 5E319 BB11 CC70 5G307 GA06 GA07 GB01 GB02 GC01

Claims (7)

[Claims] (1) a sufficiently thin gap between fibers is relatively large;
A sheet-shaped base layer obtained by applying an adhesive to a nonwoven fabric or a woven cloth having conductive properties, and conductive fillers dispersed and disposed on both side surfaces of the base layer. A conductive double-sided tape, using a flaky conductive filler, so that the ratio of the area occupied by the conductive filler per unit area of the base layer is an appropriate ratio in consideration of adhesive performance and conductive performance. Conductive double-sided tape characterized by the following. 2. The conductive double-sided tape according to claim 1, wherein a metal foil piece is used as the conductive filler. 3. The fiber is sufficiently thin and the gap between the fibers is relatively large.
A sheet-shaped base layer obtained by applying an adhesive to a nonwoven fabric or a woven cloth having conductive properties, and conductive fillers dispersed and disposed on both side surfaces of the base layer. A conductive double-sided tape, using a cloth material composed of wide fibers crushed in one direction, the ratio of the fibers per unit area of the base layer, considering the adhesive performance and conductive performance Conductive double-sided tape characterized by having an appropriate ratio. 4. The conductive double-sided tape according to claim 1, wherein a cloth material composed of fibers crushed in one direction is used,
A conductive double-sided tape, wherein a ratio of the fibers per unit area of the base layer is an appropriate ratio in consideration of adhesive performance and conductive performance. 5. The conductive double-sided tape according to claim 1, wherein an excess adhesive is removed from both side surfaces of the cloth material and the conductive filler is disposed. tape. 6. The conductive double-sided tape according to claim 5, wherein the base material layer is provided with an adhesive before the application of the adhesive in order to remove excess adhesive on both side surfaces of the cloth material. A conductive double-sided tape, to which a removing agent for facilitating the removal of the adhesive is applied. 7. The conductive double-sided tape according to claim 1, wherein the cloth material of the base layer is plated.