JPH08211401A - Thermocompression bonding method for terminal part of liquid crystal cell - Google Patents

Abstract

PURPOSE: To provide a thermocompression bonding method for the terminal parts of liquid crystal cells which executed thermocompression bonding of the terminal parts of the liquid crystal cells and the terminal parts of a TCP(tape carrier package) in the state of cooling at least the liquid crystal parts existing near the terminal parts of liquid crystal. CONSTITUTION: The extended plate part 21a of a transparent substrate 21, the terminal parts 22a of respective transparent electrodes 22, an ACF (anisotropic conductive adhesive film) 50 and the flexible tape 1 of the TCP 10 temporally press welded to the ACF 50 are arranged on a terminal receiving table 64. The gaseous nitrogen from a cooling gas supply source is supplied from a supply pipe 65 toward respective pixel parts P existing near the terminal parts 22a and respective pixel parts P is laid under a cooling state. The ACF 50 is thereafter heated by a heating head 63a via the flexible tape 11. The heating head 63a is moved upward after the thermocompression bonding of the flexible tape 11 and the respective terminal parts 22a is ended by thermal curing of the ACF 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal cell suitable for use in liquid crystal display devices, liquid crystal shutters and the like.

[0002]

2. Description of the Related Art Conventionally, as a method of mounting a driver IC in a TN type liquid crystal cell using a tape carrier package (hereinafter referred to as TCP), heat using an anisotropic conductive adhesive film (hereinafter referred to as ACF) is used. The crimping method is generally used.

[0003]

By the way, when a driver IC is mounted by TCP to a liquid crystal cell that employs, for example, an antiferroelectric liquid crystal as the liquid crystal, if the above thermocompression bonding method is employed, The following problems occur. That is, in the process of thermocompression bonding the TCP tape terminal portion to the liquid crystal cell terminal portion by ACF, the pixel portion of the liquid crystal cell located in the vicinity of the TCP tape terminal portion has a temperature higher than the temperature at which the antiferroelectric liquid crystal undergoes a phase transition. When heated to the temperature of, the phase transition occurs in the liquid crystal portion of the pixel portion. After that, even if the temperature of the pixel portion is lowered to the phase transition temperature or lower, the layer structure of the liquid crystal portion of the pixel portion is
It does not return to the original state, and is maintained in a state of phase transition different from the layer structure of the liquid crystal portion of the other pixel portion. For this reason, the display contrast of the liquid crystal cell locally has a difference due to the disorder of the phase of the liquid crystal, which causes deterioration of the display quality.

On the other hand, conventionally, the thermocompression bonding is performed after the distance between the terminal portion of the liquid crystal cell and the pixel portion is set wide enough to prevent the phase transition. However, in this case, although the phase transition does not occur in the liquid crystal portion of the pixel portion, the outer dimension of the liquid crystal cell becomes large because the distance between the terminal portion of the liquid crystal cell and the pixel portion is wide. For this reason,
This is contrary to the demand for light, thin, short and small products as liquid crystal cell products. Also, when trying to secure this lightness, thinness and shortness,
A region other than the pixel region of the liquid crystal cell, that is, a so-called frame region is unnecessarily narrowed.

Therefore, in order to deal with the above, the present invention uses thermocompression bonding between the terminal portion of the liquid crystal cell and the terminal portion of the TCP to cool at least the liquid crystal portion of the liquid crystal located near the terminal portion. It is an object of the present invention to provide a method for thermocompression-bonding a terminal portion of a liquid crystal cell, which is carried out in 1.

[0006]

In order to achieve the above object, in the invention according to claim 1, a tape carrier package (10) is provided in a terminal portion (22a) of a liquid crystal cell (S) formed by sealing liquid crystal. In the terminal thermocompression bonding method of thermocompressing the terminal portion (11), at least a liquid crystal portion of the liquid crystal located near the terminal portion (22a) is cooled during the thermocompression bonding. A terminal thermocompression bonding method is provided.

According to the second aspect of the invention, in the thermocompression bonding method for the liquid crystal cell according to the first aspect, the liquid crystal portion is cooled by cooling fluid to at least one surface side of the liquid crystal cell (S). It is characterized by being supplied. Further, in the invention described in claim 3, in the thermocompression bonding method for the liquid crystal cell according to claim 2, the cooling fluid is a cooling gas.

Incidentally, the reference numerals in parentheses of the above-mentioned respective constituent elements show the corresponding relationship with the concrete constituent elements described in the embodiments described later.

[0009]

According to the invention described in claims 1 to 3, when the terminal portion of the tape carrier package is thermocompression-bonded to the terminal portion of the liquid crystal cell, the liquid crystal is located at least in the vicinity of the terminal portion. Cool part. This allows
Even if the distance between the terminal portion of the liquid crystal cell and the liquid crystal portion is narrowed, the liquid crystal portion can maintain the same characteristics as the other liquid crystal portions during the thermocompression bonding without the temperature increase thereof. Therefore, even if the liquid crystal is, for example, an antiferroelectric liquid crystal or a ferroelectric liquid crystal, the liquid crystal portion located near the terminal portion is
It does not reach a temperature higher than the phase transition temperature and maintains the same layer structure as other liquid crystal parts. As a result, in the liquid crystal cell after the thermocompression bonding, the frame area can be properly ensured, and the difference in display contrast is not locally generated, and good display quality can be ensured.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. A thermocompression bonding method of the liquid crystal cell S (see FIG. 2) to the tape carrier package 10 (hereinafter referred to as TCP 10) will be described with reference to the process chart shown in FIG. 1. First, in the liquid crystal cell forming step S1, the liquid crystal cell S is Form.

Here, the TCP 10 is a driver I for driving the liquid crystal cell S between both flexible tapes 11.
It is configured by connecting C12 by bonding (see symbol B in FIG. 2). The liquid crystal cell S is formed by sealing the antiferroelectric liquid crystal with the seal 40 between the common substrate 20 and the counter substrate 30.

The common substrate 20 is provided with a transparent substrate 21, and an extending plate portion 21a is formed on the transparent substrate 21 so as to extend to the left of the left end of the counter substrate 30 shown in FIG. There is. A plurality of transparent electrodes 22 are formed on the inner surface of the transparent substrate 21 in the left-right direction shown in FIG. 2, and each of these transparent electrodes 22 is provided with a terminal at an extended end portion on the extended plate portion 21a. It constitutes the section 22a. An alignment film 23 is formed on the inner surface of the transparent substrate 21 via each transparent electrode 22.

The counter substrate 30 is provided with a transparent substrate 31, and a plurality of transparent electrodes 32 are provided on the inner surface of the transparent substrate 31, together with the transparent electrodes 22 and the antiferroelectric liquid crystal, in a grid-like pixel portion. (Illustrated by reference numeral P in FIG. 2). Next, in the ACF attaching step S2, the anisotropic conductive adhesive film 50 (hereinafter, referred to as ACF50) is attached on the terminal portions 22a of each transparent electrode 22 (see FIG. 3A). Next, in the TCP temporary pressure bonding step S3, as shown in FIG.
One of the two flexible tapes 11 is positioned on each ACF 50 and temporarily pressure-bonded.

Then, in the TCP main pressure bonding step S4,
The liquid crystal cell S and TCP 10 are set in the thermocompression bonding apparatus 60 and thermocompression bonding processing is performed as follows. First, the liquid crystal cell S is placed on the table 61 of the thermocompression bonding apparatus 60. At this time, the liquid crystal cell S is placed in the table 61 so that the terminal portions 22a of the liquid crystal cell S and the pixel portions P near the ACF 50 are located on the left side of the left end of the table 61 in FIG.
Place and fix on top.

The table 61 is rotatably supported on the support base 61a and is movable in the left-right direction in the drawing. Further, the support base 61a is movable along both rails 61b (only one rail 61b is shown in FIG. 2) installed on the base 62 at right angles to the moving direction of the table 61. After placing and fixing as described above, the table 6
1 is moved to the position shown in FIG. 2, and the extension plate portion 21 of the transparent substrate 21 is placed on the terminal receiving base 64 provided on the base 62.
a, the terminal portion 22a of each transparent electrode 22, the ACF 50, and the flexible tape 11 of the TCP 10 that is temporarily pressure-bonded to the ACF 50.

Here, as shown in FIG. 2, the terminal pedestal 64 is located to the left of the left end of the transparent electrode 31 in the drawing so that heat from a heater head 63a, which will be described later, is not transferred to each pixel portion of the liquid crystal cell S. It is located towards In addition, the terminal cradle 6
Directly above 4 is the horizontal portion 62a of the L-shaped arm of the base 62.
The heater head 63a of the air cylinder 63 that is hung down from is located. The heater head 63a is moved up and down by controlling the air pressure of the air cylinder 63, and heat energy is generated by electric power from a power source (not shown).

A supply pipe 65 for supplying nitrogen gas as a cooling gas from a cooling gas supply source (not shown).
Are arranged immediately below the portion of the transparent substrate 21 corresponding to each pixel portion P (that is, the liquid crystal portion of the antiferroelectric liquid crystal located near the terminal portion 22a). However, the distance between the supply port of the supply pipe 65 and the lower surface of the transparent substrate 21 is about 5 mm, and the supply amount of nitrogen gas in the supply pipe 65 is 50 mm.
It is liter / min.

After the state required for thermocompression bonding of the liquid crystal cell S and the TCP 10 via the ACF 50 is set in this way, the supply pipe 65 is used to set each pixel portion P of the transparent substrate 21.
The nitrogen gas is supplied to the portion corresponding to the above to keep each pixel portion P in the cooled state. After that, the heating head 63a is moved downward by the air cylinder 63, and pressure is applied to the ACF 50 on each terminal portion 22a via the flexible tape 11. At the same time, the heating head 63a heats the ACF 50 via the flexible tape 11. Then, after the ACF 50 is thermoset and the thermocompression bonding of the flexible tape 11 and each terminal portion 22a is completed, the heating head 6
Move 3a upward.

As described above, in the cooling state with nitrogen gas for each pixel portion P in the vicinity of each terminal portion 22a, thermocompression bonding with the heating head 63a as described above is performed. Therefore, even if the distance between each terminal portion 22a of the liquid crystal cell S and each pixel portion P is narrowed, in the process of thermocompression bonding between the tape terminal portion of the TCP 10 and the terminal portion of the liquid crystal cell S by the ACF 50, the liquid crystal cell Each terminal portion 22 of the S anti-ferroelectric liquid crystal
The liquid crystal portion of each pixel portion P located in the vicinity of “a” is maintained at the same layer structure as the other liquid crystal portions without reaching a temperature equal to or higher than its phase transition temperature.

Therefore, in the liquid crystal cell S after the thermocompression bonding, the frame region can be properly secured, and the display contrast is not locally varied, and the good display quality can be secured. . In addition, since the terminal pedestal 64 is located on the left side of the left end of the transparent substrate 31 in FIG. 2 in the above-described thermocompression bonding, the thermal energy of the heating head 63a passes through the terminal pedestal 64 to each pixel. It is not transmitted to department P. Therefore, the respective pixel portions P can be efficiently cooled by the nitrogen gas.

After the completion of the TCP main pressure bonding step S4, the TCP1 is bonded in the circuit board soldering step S5.
The circuit board is connected to the driver IC 12 of 0. By the way, when the effect of thermocompression bonding by the thermocompression bonding method according to the above example was compared with the effect of not cooling with nitrogen gas (25 ° C.) by experiment, the results shown in FIG. 4 were obtained. In this result, the characteristic when there is cooling by the cooling gas is shown by the curve La, while the characteristic when there is no cooling by the cooling gas is shown by the curve Lb.

Here, the interval x is as shown in FIG.
The pixel portion P and the heater head 63a near each terminal portion 22a,
Represents the interval of. In addition, the liquid crystal cell used in this experiment
The phase transition temperature of the antiferroelectric liquid crystal is the antiferro phase (S_CA
* Phase) and smectic phase (S _APhase) at 70 ° C
Again, S_ABetween the phase and the isotropic liquid (ISO) 98
℃.

Therefore, according to the curve La, each terminal portion 2
It can be seen that the liquid crystal portion of the pixel portion P near 2a is maintained in the S _CA * phase at the interval x = 4 mm or more. On the other hand, according to the curve Lb, the pixel portion P near each terminal portion 22a
It can be seen that the liquid crystal portion of can be maintained in the S _CA * phase only when the interval x is 8 mm or more. In addition, each terminal portion 22
When the pixel portion P in the vicinity of a was cooled, the display quality of the liquid crystal cell was not degraded even at the interval x = 4 mm, whereas when the pixel portion P was not cooled, the interval x = 7 m.
At m, the display quality was deteriorated.

In the above embodiment, the liquid crystal cell S
Although the pixel portion P in the vicinity of each terminal portion 22a is cooled only from below, instead of this, for example, as shown by the chain double-dashed line in FIG.
A supply pipe 66 similar to that of No. 5 is arranged so as to face the supply pipe 65 via the liquid crystal cell S, and the nitrogen gas from the cooling gas supply source is also supplied by the supply pipe 66 in the vicinity of the terminal portion 22a of the transparent substrate 31. Alternatively, each pixel portion P in the vicinity of the terminal portion 22a may be placed in a cooling state from above and below. Further, each pixel portion P in the vicinity of the terminal portion 22a may be kept in a cooled state only with the nitrogen gas from the supply pipe 66.

When supplying the nitrogen gas from the supply pipe 66, the Teflon (registered trademark) cushion sheet 67 is attached to the heater head 63, as shown by the chain double-dashed line in FIG.
The heating temperature of the heater head 63a may be prevented from lowering due to the cooling action of the nitrogen gas from the supply pipe 66. The Teflon cushion sheet 67 is for making the crush of the AFC 50 uniform.

Further, in the above embodiment, the liquid crystal cell S
Terminal part 22a of TCP and flexible tape 11 of TCP10
Although the thermocompression bonding is performed by the ACF 50, the thermocompression bonding is not limited to this, and the thermocompression bonding may be performed by an isotropic conductive adhesive tape, for example. Further, in carrying out the present invention, the cooling gas is not limited to nitrogen gas,
For example, compressed air used in a factory may be used as long as it has a cooling capacity. In this case, not only gas,
Various fluids such as a cooling liquid or a cooling solid may be used.

Further, in implementing the present invention, the cooling target is not limited to the pixel portion P in the vicinity of each terminal portion 22a of the liquid crystal cell S, but all pixel portions may be cooled. Further, in the above embodiment, an example in which the antiferroelectric liquid crystal is adopted as the liquid crystal of the liquid crystal cell S has been described, but the invention is not limited to this, and for example, a ferroelectric liquid crystal may be adopted.

[Brief description of drawings]

FIG. 1 is a process drawing showing a thermocompression bonding method for a terminal portion of a liquid crystal cell.

FIG. 2 is a fragmentary side view showing a state in which a TCP flexible tape is temporarily press-bonded to a terminal part of a liquid crystal cell via an ACF and set in a thermocompression bonding apparatus.

FIG. 3 is a partially cutaway side view showing a state in which an ACF is attached to a terminal portion of a liquid crystal cell and a state in which a TCP flexible tape is temporarily pressure-bonded to the ACF.

FIG. 4 is a graph showing the relationship between the temperature of the pixel portion and the interval x in relation to the phase transition of the liquid crystal portion of the pixel portion.

[Explanation of symbols]

S ... Liquid crystal cell, 10 ... TCP, 11 ... Flexible tape, 22a ... Terminal part, 63a ... Heater head, 65, 66 ... Supply pipe.

Claims (3)

[Claims] 1. A terminal thermocompression bonding method for thermocompression bonding a terminal of a tape carrier package to a terminal of a liquid crystal cell in which liquid crystal is sealed, wherein at least at least the vicinity of the terminal of the liquid crystal is adhered during the thermocompression bonding. A method for thermocompression-bonding a terminal portion of a liquid crystal cell, which comprises cooling a liquid crystal portion located. 2. The thermocompression bonding method for a liquid crystal cell according to claim 1, wherein the liquid crystal portion is cooled by supplying a cooling fluid to at least one surface side of the liquid crystal cell. 3. The thermocompression bonding method for a liquid crystal cell according to claim 2, wherein the cooling fluid is a cooling gas.