JPH0561063A - Method for reinforcing connection of electro-optical device - Google Patents

Abstract

PURPOSE:To prevent the defective connection by connecting a flexible printed board to the terminal of a liq. crystal panel substrate and irradiating the vicinity with UV to cure the resin coating the joint. CONSTITUTION:A flexible printed board 14 of polyethylene terephthalate and polyimide is electrically connected to the terminal 2 formed on a liq. crystal panel substrate 1, and the printed board 4 is previously irradiated with UV. The joint is coated with an UV-curing resin 5 and again irradiated with UV to cure the resin. Consequently, the reinforcing effect is improved, adhesion strength is increased, and the galvanic corrosion is reduced. Accordingly, the joint is hardly broken even if expansion or contraction is caused due to heating or cooling when the device is used or the external force is exerted thereon.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of reinforcing the connection of an electro-optical device.

[0002]

2. Description of the Related Art Conventionally, a transparent conductive film terminal of an electro-optical element such as an electro-optical element such as a liquid crystal display element or an electrochromic element, and a circuit board such as a flexible printed board for connecting to an external drive circuit or Conductive connection by arranging the terminals of the circuit board on which the drive circuit is mounted so that both terminals face each other, and placing a conductive adhesive such as solder, anisotropic conductive film, silver paste, etc. between both terminals. Is being done.

The conductive connecting portion may be peeled off due to an external force applied to the electro-optical element or the flexible printed board, a difference in thermal expansion coefficient between the two. In order to reinforce the conductive connecting portion, a resin such as an ultraviolet curable resin is applied to the flexible printed circuit board in the conductive connecting portion and the substrate around the flexible printed circuit board and cured.

[0004]

However, when a resin such as a UV-curable resin is applied to a polyester-based flexible printed circuit board, the adhesive force between the substrate and the UV-curable resin is low, so that there is no reinforcing effect. In addition, there is a risk that the weak portion of the conductive connection portion may peel off due to expansion and contraction due to heating and cooling, and further external force applied thereto.

In particular, in recent liquid crystal display devices and the like, with higher precision, the number of terminals has increased and the pitch thereof has become finer. Therefore, one terminal 1
The area of each piece is reduced, and it is easy for wire breakage to occur even with a weak external force. Furthermore, in such a liquid crystal display element, even if one of a large number of terminals is broken, it becomes defective. Therefore, there has been a demand for a conductive connection method that does not easily cause defective conductive connection even after repeated expansion and contraction.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is provided outside the seal of an electro-optical element in which an electro-optical medium is sandwiched between a pair of substrates with electrodes and the periphery is sealed. A method of reinforcing a connection of an electro-optical device in which a terminal is formed on a board and a flexible board is conductively connected to the terminal by a conductive adhesive, by irradiating ultraviolet rays in the vicinity of the conductively connected flexible board, A method of reinforcing the connection of an electro-optical device, which comprises covering with a resin and curing the resin.

In the present invention, a conductive film terminal on a polyester flexible printed circuit board is conductively connected to a conductive film terminal formed on a substrate such as an electro-optical element through a conductive adhesive, and then the conductive connection is made. UV irradiation of the part of the polyester flexible printed circuit board in advance,
By covering it with UV-curable resin, there is the problem of expansion and contraction due to heating and cooling during use of the manufactured device, and peeling of the long-distance connection part even if external force is applied to this. It becomes difficult. Of course, it is desirable that the ultraviolet curable resin used here has resistance to thermal stress caused by expansion and contraction due to heating and cooling.

The terminals of the conductive film formed on the substrate of the present invention include fine wires or foils of copper, aluminum, chromium or the like, indium oxide-based or tin oxide-based transparent conductive films, or nickel, gold, It is possible to use the one that is plated with silver or the like and is baked with a conductive paste.

Although a simple printed circuit board can be used as this substrate, the present invention is suitable for a substrate of an electro-optical element. The electro-optical element is an element in which an electro-optical medium such as a liquid crystal substance or an electrochromic substance is sandwiched between substrates such as glass and plastic having at least one of electrodes made of a transparent conductive film, and in particular, a liquid crystal substance is used. It is suitable for the liquid crystal display element used. In addition, a polyester-based material is typically used as the flexible substrate. Specifically, polyethylene terephthalate (PE
T), polybutylene terephthalate (PBT), polyethylene terephthalate-isocyanate copolymer, PE
Examples include a mixture of T and PBT, polytrimethylene terephthalate, polytetramethylene terephthalate, and the like.

In the present invention, the terminals of the substrate such as the electro-optical element and the terminals of the polyester flexible printed board are conductively connected by a conductive adhesive material. For this,
As has been done conventionally, the terminals of the board and the terminals of the polyester-based flexible printed board are arranged so that both terminals face each other, and solder, anisotropic conductive film, silver paste, or other conductive material is placed between them. A conductive adhesive may be placed and conductively connected.

In the present invention, in order to reinforce the conductive connecting portion of the flexible printed board, the connecting portion is previously irradiated with ultraviolet rays when covered with resin. Irradiation dose is 1000-10
It is preferably 000 mJ.

The resin used in the present invention may be a known resin which has been conventionally used to reinforce a conductive connecting portion, and may be used for a substrate, a flexible printed circuit board, a conductive connecting portion, etc. during curing or subsequent use. A resin such as an ultraviolet curable resin or a thermosetting resin that does not have an adverse effect can be used. From the viewpoint of productivity, ultraviolet-curable resins such as modified acrylate resin and urethane acrylate resin are particularly preferable.

Such a resin is supplied and applied by a dispenser, a printing machine or the like so as to cover at least a part of the polyester flexible printed circuit board of the conductive connection part and the board around it. After that, in the case of a thermosetting resin, it is heated to cure the resin, and in the case of a UV curable resin, U
Irradiate V to cure the resin.

As a result, it is possible to reinforce the conductive connecting portion, and a connection in which defects such as peeling of the conductive connecting portion are unlikely to occur can be obtained.

In addition to the above, the present invention can be applied in various ways within a range that does not impair the effects of the present invention.

[0016]

According to the present invention, when the terminal of the conductive film formed on the substrate of the electro-optical element is conductively connected to the terminal of the conductive film on the polyester flexible printed board through the conductive adhesive, the conductive connection is made. The part of the polyester-based flexible printed circuit board is previously irradiated with ultraviolet rays, and the upper part is covered with resin.

In the present invention, a polyester-based flexible printed circuit board, which is generally difficult to adhere to, is subjected to ultraviolet irradiation treatment to wash the surface and cut the bonds on the polymer surface to form a form that facilitates bonding, that is, activate the surface. It can be considered that, as a result, the wettability with the resin is improved, and finally the adhesive strength is increased.

[0018]

EXAMPLE As shown in FIG. 1, a terminal 2 formed on a liquid crystal panel substrate 1 was provided with PET (polyethylene terephthalate), PI
After the (polyimide) flexible printed circuit board 4 was conductively connected with the conductive adhesive 3, the flexible printed circuit board 4 was irradiated with ultraviolet rays (UV) in advance, and the flexible printed circuit board 4 was covered with an ultraviolet curable resin 5 and cured by ultraviolet rays.

As a comparative example, PE, which is similarly conductively connected,
The flexible printed circuit board of T was previously irradiated with UV and covered with a UV curable resin 5 to be UV cured.

The peeling forces of both were as shown in Table 1.

[0021]

[Table 1]

[0022]

INDUSTRIAL APPLICABILITY The present invention is an electro-optical device in which a flexible flexible printed circuit board is conductively connected to terminals formed on an electro-optical element, the flexible printed circuit board is previously irradiated with UV, and the flexible printed circuit board is covered with UV resin. By strengthening by UV irradiation, the reinforcing effect can be improved and the electrolytic corrosion resistance can be improved by improving the adhesion. Further, there is no change in the resistance of the heating / cooling cycle or the like.

[Brief description of drawings]

FIG. 1 is a sectional view showing a method of the present invention.

[Explanation of symbols]

 1 Liquid crystal panel substrate 4 Flexible printed circuit board 5 Resin

Claims (3)

[Claims] 1. A terminal is formed on a substrate outside a seal of an electro-optical element in which an electro-optical medium is sandwiched between a pair of substrates with electrodes and the periphery is sealed, and a flexible substrate is conductively connected to the terminal by a conductive adhesive material. A method for reinforcing the connection of an electro-optical device, the method comprising: irradiating ultraviolet rays in the vicinity of a conductively connected flexible substrate, covering the connection portion with a resin, and curing the resin, thereby reinforcing the connection of the electro-optical device. Method. 2. The amount of ultraviolet rays applied to the flexible substrate is 10.
It is 00-10,000 mJ, It is characterized by the above-mentioned.
To reinforce the connection of electro-optical devices. 3. The method for reinforcing the connection of the electro-optical device according to claim 1, wherein the resin is an ultraviolet curable resin made of a modified acrylate resin or a urethane acrylate resin.