JPS61277179A - Conductive anisotropic adhesive sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a conductive method for bonding wiring boards each having a connecting conductive layer thereon and electrically connecting each connecting conductive layer. This invention relates to an anisotropic adhesive sheet.

C. Summary of the Invention] The present invention relates to an electrically conductive anisotropic adhesive sheet, in which aggregates of electrically conductive particles are contained in a hot-melt adhesive in a desired arrangement, thereby forming a connection conductive layer. Each connection conductive layer between the bonded wiring boards is made to have low connection resistance, high insulation resistance between adjacent connection conductive layers, and to reduce short-circuit accidents at the ends between adjacent connection conductive layers. , so that we can connect.

[Conventional technology]

Conventional conductive anisotropic adhesive sheets contain hot-melt adhesive,
It was constructed by randomly dispersing conductive particles such as low melting point solder metal particles.

[Problem that the invention seeks to solve]

However, when such a conductive anisotropic adhesive sheet is used to bond wiring boards together and connect their respective connection conductive layers, the connection resistance of each connection conductive layer does not decrease very much, and the connection resistance between adjacent connection conductive layers If the insulation resistance is not high enough, or if the adhesive between each wiring conductive layer is washed away at the end when each wiring board is bonded, conductive particles may clump together and cause problems between adjacent connecting conductive layers. There was a risk of a short circuit.

In view of these points, the present invention provides a structure in which each connecting conductive layer between wiring boards on which connecting conductive layers are deposited has low connection resistance, high insulation resistance between adjacent connecting conductive layers, and The purpose of this paper is to propose a conductive anisotropic adhesive sheet that can connect conductive layers with fewer short-circuit accidents at the ends.

[Means for solving problems]

The electrically conductive anisotropic adhesive sheet according to the present invention is constructed by containing aggregates of electrically conductive particles in a desired arrangement in a hot-melt adhesive.

[Effect]

According to the present invention, since aggregates of conductive particles are contained in a hot-melt adhesive in a required arrangement, the arrangement of the aggregates is determined by the pattern of the connecting conductive layer of the wiring board to be bonded. By selecting the conductive layer according to the above, the connection resistance of each connecting conductive layer is low, the insulation resistance between adjacent connecting conductive layers is high, and short-circuit accidents at the ends between adjacent connecting conductive layers are reduced. Can be done.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail together with its manufacturing method with reference to FIGS. 1 and 2. Figures 1A and 2
As shown in the figure, aggregates (1) of conductive particles are printed in a grid pattern on a release sheet (3) made of, for example, polyethylene terephthalate, by, for example, a silk screen method. The density of the conductive particle aggregates (1) is made higher in the direction of the connection conductive layer of the wiring board and lower in the direction orthogonal thereto [however, the density of the conductive particle aggregate (1) is increased in the direction perpendicular to the direction of the connection conductive layer of the wiring board.
2, 3, ...) times].

The conductive particle aggregate (1) has a diameter of, for example, 3 μm.
Prepare silver particles of the same diameter and the same weight parts of a phenol resin as an adhesive, and dissolve them in a mixture of toluene and methyl ethyl ketone as a solvent, for example, 0.3
It has a do-nod shape with a diameter of mm.

Then, as shown in FIG. 1B, the release sheet (3) and the conductive particle aggregate (1) are entirely coated with a hot-melt adhesive (2) as an insulator. This hot-melt adhesive (2) uses an adhesive having a lower melting temperature than the adhesive of the conductive particle aggregate (1), such as a polyester resin.

Next, with reference to FIGS. 3 and 4, the conductive anisotropic adhesive sheet obtained according to the present invention is used to bond the wiring boards together and to electrically connect the respective connecting conductive layers. An example of the case will be explained. (5) and (6) indicate wiring boards (flexible wiring boards) to be bonded to each other, including an insulating board (5a) made of, for example, polyethylene terephthalate;
Connecting conductive layers (5b) and (6b) made of carbon or copper, for example, are formed on (6a) and are parallel to each other in the form of strips so as to correspond to each other. Then, the adhesive (2) side of the conductive anisotropic adhesive sheet (4) obtained according to the present invention is pasted on the connection conductive layer (5b) side at the end of one wiring board (5), and then The release sheet (3) is peeled off, and the connection conductive layer (6b) side of the end of the wiring board (6) is pasted onto the adhesive (2) (see FIG. 4A). In FIG. 3, the release sheet (3) attached to the adhesive sheet (4) is not shown. After that, connect the wiring board (5
), the adhesive sheet (4) and the wiring board (6) are subjected to a temperature of 130°C and a pressure of 40 kg/ant for 30 minutes.
Add seconds. As a result, as shown in FIG. 4B, the adhesive (2) melts, and the aggregate (1) of conductive particles between the connecting conductive layers (5b) and (6b) is crushed, and both the connecting conductive layers ( 5b
), (6b), and serves as a conductor that electrically connects the wiring board (5) with low resistance.
, (6) are firmly adhered. In this case, the peel strength is quite strong at 1.71 qr/cut. Further, the aggregate (1) of conductive particles between the adjacent connection conductive layers (5b) and (6b) is isolated between them, and the conductive particle aggregate (1) between the adjacent connection conductive layers (5b) and (6b)
There is no risk of short-circuiting between 5b) and (6b).

Next, the connection conductive layer (5b) of the wiring board (5), (6),
The results of measuring the resistance between the connecting conductive layers (5b) and (6b) after aging when (6b) is carbon are shown. If the aging time is zero, the resistance is 1. It was OK. When the objects were aged at 80° C. for 48 hours and 360 hours, respectively, the resistance was 1.3Ω.

Incidentally, if the phenol resin among the components of the conductive particle aggregate (1) is removed, the resistance will be 1.0 when the aging time is zero. When the target material was aged at 80° C. for 48 hours and 360 hours, the resistance increased to 20 Ω, respectively. In this case, the peel strength is also considerably lower than in the above case.

In the case of the above embodiment, the phenol resin easily adheres to carbon and copper, and its melting temperature is 130°C. The melting temperature of polyethylene terephthalate, which is the material of the insulating substrates (5a) and (6a) of the wiring boards (5) and (6), is 10
It is 0°C. Furthermore, the melting temperature of the polyester adhesive, which is the hot-melt adhesive (2), is 50°C.

Therefore, by using the conductive anisotropic adhesive sheet of this example, it becomes possible to bond wiring boards together by low temperature and low pressure pressing.

〔Effect of the invention〕

According to the present invention described above, each of the connection conductive layers between the wiring boards on which the connection conductive layers are deposited has a low connection resistance.
In order to increase the insulation resistance between adjacent connected conductive layers and reduce short circuit accidents at the ends between adjacent connected conductive layers,
A conductive anisotropic adhesive sheet that can be connected can be obtained.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the manufacturing process of a conductive anisotropic adhesive sheet according to the present invention, Figure 2 is a partial plan view showing a part of the manufacturing process, and Figure 3 is a wiring board connection process. The perspective view and FIG. 4 are cross-sectional views showing the process of connecting the wiring board. (1) is an aggregate of conductive particles, (2) is a hot melt adhesive,
(3) is a release sheet, (4) is a conductive anisotropic adhesive sheet,
(5) and (6) are wiring boards. Figure 3

Claims (1)

[Claims] 1. A conductive anisotropic adhesive sheet comprising an aggregate of conductive particles contained in a hot-melt adhesive in a desired arrangement.