JP2001034189A - Manufacturing method of liquid crystal display device - Google Patents

Abstract

(57) Abstract: A multilayer printed wiring board (5) having a resin impregnated glass woven fabric as an insulating layer and a liquid crystal panel glass substrate (4) are TAB10.
In the manufacture of the liquid crystal display device connected via the, the copper foil circuit of the TAB 10 is prevented from being disconnected. A multilayer printed wiring board (5) has a coefficient of thermal expansion of 13
ppm / ° C or less. The specific means is to set the thermal expansion coefficient of the glass yarn constituting the glass woven fabric to 4 ppm / ° C. or less and the elastic modulus to 7000 kg / mm ² or more. In addition, the modulus of elasticity of the resin impregnated in the glass woven fabric was set to 200 kg / mm.
² or less, the coefficient of thermal expansion of the glass thread is 6 ppm / ° C. or less, and the elastic modulus is 7000 kg / mm ² or more. First, the secondary connection part of the TAB is fixedly connected to the terminal arranged on the side edge of the liquid crystal panel glass substrate, and then the primary connection part of the TAB and the terminal arranged on the multilayer printed wiring board are fixed. Connecting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device in which a multilayer printed wiring board having a glass woven fabric impregnated with a thermosetting resin as an insulating layer and a liquid crystal panel glass substrate are connected via TAB.

[0002]

2. Description of the Related Art As shown in FIG. 2, a TAB 10 is a flexible printed wiring board having a copper foil circuit formed on a polyimide film. In this, an LSI 1 for driving a liquid crystal display is mounted. In general, a technique for connecting a printed wiring board and a liquid crystal panel glass substrate via a TAB 10 is as follows. First, the secondary connection portion 2 of the TAB 10 is arranged on the side edge of the liquid crystal panel glass substrate via an anisotropic conductive film. Connected to the terminal. Next, the primary connection portion 3 of the TAB 10 is connected to terminals arranged on the printed wiring board via an anisotropic conductive film or by soldering. In recent years, electronic devices have been reduced in size and weight, and the range of use of liquid crystal displays as display devices has been increasing. In addition, as liquid crystal displays have become larger, higher definition displays have been developed. Along with this, the wiring density of the TAB connecting the liquid crystal panel glass substrate and the printed wiring board has also increased, and the thickness of the copper foil constituting the TAB circuit has shifted from the conventional 35 μm thickness to 18 μm thickness, and the thinned copper Foil circuit is fragile. Also, in order to increase the area occupied by the liquid crystal panel in the case by making the frame around the case containing the liquid crystal panel glass substrate as small as possible, the pad area connecting the TAB and the printed wiring board is becoming smaller year by year. (Slim TAB).
In such a situation, when a general-purpose FR-4 copper-clad laminate, which is currently most frequently used, is used as a printed wiring board, heat is applied during the connection work between the printed wiring board and the liquid crystal panel glass substrate, and then a cooling / heating cycle is applied. In such a case, there is a problem that the TAB copper foil circuit is disconnected. This disconnection is caused by the TAB connected to the center of the side edge of the liquid crystal panel glass substrate and the TAB connected to both ends of the side edge.
It happens a lot. This phenomenon becomes more remarkable when a printed circuit board having a multilayered circuit is used and this is connected to a liquid crystal panel glass substrate via a TAB.

[0003]

An object of the present invention is to provide a multi-layer printed circuit board having a glass woven fabric impregnated with a resin as an insulating layer and a liquid crystal panel glass substrate by a TA method.
In the manufacture of a liquid crystal display device connected via B, the temperature during assembly and subsequent cooling / heating cycle
The purpose is to prevent disconnection of the copper foil circuit of B.

[0004]

In order to solve the above-mentioned problems, a method for manufacturing a liquid crystal display device according to the present invention is arranged such that a secondary connection portion of a TAB and a side edge of a liquid crystal panel glass substrate are first arranged. A method of fixedly connecting a terminal and then a fixed connection between a primary side connection portion of the TAB and a terminal arranged on the multilayer printed wiring board, wherein the multilayer printed wiring board has a coefficient of thermal expansion of 13 ppm / ° C. or less. Is used.

The coefficient of thermal expansion of a multilayer printed wiring board can be reduced by specifying the glass thread constituting the glass woven fabric of the multilayer printed wiring board as follows. That is, the thermal expansion coefficient of the glass thread is 4 ppm / ° C. or less, and the elastic modulus of the glass thread is 7000 kg / mm ² or more. Further, even if the resin impregnated in the glass woven fabric and the glass thread constituting the glass woven fabric are specified as follows, the coefficient of thermal expansion of the multilayer printed wiring board can be reduced. That is, the elastic modulus of the resin is 200 kg / mm ² or less, the thermal expansion coefficient of the glass thread is 6 ppm / ° C. or less, and the elastic modulus of the glass thread is 7000.
kg / mm ² or more. The specification of the thermal expansion coefficient and the elastic modulus of the glass yarn is that the glass yarn itself is within the above-described specific range, and that the apparent thermal expansion coefficient and the elastic modulus of the glass woven fabric are within the above-described specific range. Including.

As shown in FIG. 1, a plurality of TABs 10 are arranged along the side edge of the liquid crystal panel glass substrate 4, and the liquid crystal panel glass substrate 4 and a multi-layer printed wiring having substantially the same length as this. The substrate 5 is connected. TAB connected to the center of the side edge of the liquid crystal panel glass substrate 4
As a result of a detailed analysis of a phenomenon in which disconnection occurs more frequently in the copper foil circuit of TAB 10 connected to both ends of the side edge as compared with No. 10, the following became clear. That is, the conventionally used multilayer printed wiring board has a thermal expansion coefficient of 17 pp.
m / ° C. Since the copper foil circuit is provided in multiple layers, the coefficient of thermal expansion is further increased due to the effect of the copper foil having a large coefficient of thermal expansion. On the other hand, the liquid crystal panel glass substrate 4 has a coefficient of thermal expansion of 5 to 8 ppm / ° C. As described in the prior art, the technology for connecting the liquid crystal panel glass substrate 4 and the multilayer printed wiring board 5 via the TAB 10 is firstly a TAB.
The secondary side connection portion 2 of B is connected to terminals arranged on the side edge of the liquid crystal panel glass substrate 4 via anisotropic conductive rubber. Therefore, the next time the primary side connection portion 3 of the TAB 10 is connected to the terminals arranged on the multilayer printed wiring board 5 by anisotropic conductive rubber or soldering,
B10 is fixed to the liquid crystal panel glass substrate 4 having a small coefficient of thermal expansion. Since the work of connecting the TAB 10 to the multilayer printed wiring board 5 requires heating, the multilayer printed wiring board 5 expands due to the heat and has a dimension longer than usual. In such a state, the multilayer printed wiring board 5 is
When connected to the AB 10 and cooled to room temperature, the multilayer printed wiring board 5 tends to shrink to its original size. However, the surface of the multilayer printed wiring board 5 to which the TAB 10 is connected is regulated by the presence of the liquid crystal panel glass substrate 4 because the secondary connection portion 2 of the TAB 10 is connected to and integrated with the liquid crystal panel glass substrate 4. The shrinkage is suppressed.
One surface of the multilayer printed wiring board 5 is quasi-integrated with the liquid crystal panel glass substrate 4, and only the surface of the multilayer printed wiring board 5 opposite to the surface to which the TAB 10 is connected contracts. , As shown in FIG.
Is connected to the convex surface. The warp of the multilayer printed wiring board 5 increases toward both ends of the side edge of the liquid crystal panel glass substrate 4, and in this portion, the multilayer printed wiring board 5 does not exist on the extension plane of the liquid crystal panel glass substrate 4. As a result, a bending stress acts on the copper foil circuit of the TAB 10 to easily crack. This is because the copper foil circuit is strong against tensile stress and shear stress but weak against bending stress. Further, when the temperature of the multilayer printed wiring board 5 is lower than the normal temperature in the state in which the multilayer printed wiring board 5 is aligned as described above, the multilayer printed wiring board 5 has a larger thermal expansion coefficient than the liquid crystal panel glass substrate 4, and therefore the contraction amount is large. Further, the warp becomes remarkable, and the copper foil circuit of the TAB 10 is more easily cracked.

From the above viewpoints, in the method according to the present invention, the work of connecting the TAB by setting the thermal expansion coefficient of the multilayer printed wiring board connected to the liquid crystal panel glass substrate via the TAB to 13 ppm / ° C. or less. Thermal expansion of the multilayer printed wiring board at the time is reduced. Thereafter, when the multilayer printed wiring board is cooled to room temperature, the shrinkage of the multilayer printed wiring board is small, the warpage is reduced, and the bending stress acting on the TAB copper foil circuit is reduced. The coefficient of thermal expansion α of the multilayer printed wiring board is determined based on the SCHAPPERY empirical formula shown in (Equation 1). Based on (Equation 1), the thermal expansion coefficient α of the multilayer printed wiring board is set to a specific value by setting the elastic modulus of the resin of the multilayer printed wiring board and the linear expansion coefficient and the elastic modulus of the glass thread constituting the glass woven fabric to specific values. The above small value is set. The thermal expansion coefficient of the glass thread constituting the glass woven fabric is 4 ppm / ° C. or less, and the elastic modulus of the glass thread is 7000 kg / ° C.
If it is set to mm ² or more, the task can be achieved without any problem. The elastic modulus of the resin of the multilayer printed wiring board is 200kg /
If specified below mm ² , the thermal expansion coefficient of the glass thread is 6 ppm
/ ° C. or less, and the elasticity of the glass thread is made 7000 kg / mm ² or more, so that the object can be achieved without any problem.
The elastic modulus of the resin of the multilayer printed wiring board is 200 kg / mm ²
In the case specified below, the expansion or contraction stress is absorbed by the resin having a small elastic modulus, so that the glass thread can have a somewhat large thermal expansion coefficient.

[0008]

(Equation 1)

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a method for manufacturing a liquid crystal display device according to the present invention, a resin used for a multilayer printed wiring board includes a thermosetting resin and a thermoplastic resin. These resins may contain the same or different kinds of flexible resins, coloring agents, inorganic / organic fillers, curing agents and the like. The thermosetting resin is, for example, an epoxy resin, a phenol resin, a polyimide resin, a polyester resin, or the like. The thermoplastic resin is preferably a resin having heat resistance,
Examples include polyether sulfone, polyphenyl ether, and liquid crystal resin.

[0010] Generally, the glass yarn is desirably a composition having a total content of SiO ₂ and Al ₂ O ₃ of 65% by weight or more and a small amount of extracted ion components. For example, E glass, S glass, Q
Glass and D glass are desirable. The glass woven fabric impregnated with resin is woven by mixing the above glass yarns alone or in combination. For example, the warp and the weft can be woven using the same kind of glass thread, or the warp and the weft can be woven using different glass threads.

[0011]

EXAMPLES Examples and comparative examples according to the present invention will be described below in detail. Examples 1 to 5 and Comparative Examples 1 to 5 With a density of 65 strands / 25 mm, and a strand of 55 strands / 25 mm across a strand in which 200 glass threads having a diameter of 7 μm are converged,
A 100 μm thick glass woven fabric was woven. After heat cleaning the glass woven fabric, it was treated with a coupling agent. Tables 1 to 3 show the thermal expansion coefficient and the elastic modulus of the glass yarn used in each example.
Shown in The glass yarn having a coefficient of thermal expansion of 5.5 ppm / ° C. and an elastic modulus of 7100 kg / mm ^{2 in} the table is made of E glass. Also, a brominated bisphenol A-based epoxy resin (“YDB-500EK60” manufactured by Toto Kasei) 100
Parts by weight, 2.5 parts by weight of dicyandiamide, 2-ethyl 4
-Methylimidazole (catalyst) was uniformly dissolved, and acrylic rubber ("BP-590" manufactured by TOPE) was uniformly dissolved therein to prepare a resin varnish for impregnating the glass woven fabric. The elastic modulus when this resin varnish was cured is also shown in Tables 1 to 3. The adjustment of the elastic modulus of the resin was performed by adjusting the amount of the acrylic rubber. In each table, those having a resin elastic modulus of 290 kg / mm ² use a resin varnish containing no acrylic rubber. Each resin varnish was impregnated into each glass woven fabric and dried to prepare a prepreg for forming an inner wiring board and a prepreg for multilayer bonding. First, a 36 μm-thick electrolytic copper foil is overlaid on both sides of the prepreg layer for an inner wiring board, and the temperature is 170 ° C. and the pressure is 40 kg / cm ^{2 by a} heat medium oil press.
For 70 minutes to obtain a double-sided copper-clad laminate. The copper foil of this double-sided copper-clad laminate was etched and blackened by a predetermined method to obtain an inner printed wiring board. next,
Adhesive prepregs are stacked on both surfaces of the inner printed wiring board one by one, electrolytic copper foil of 18 μm thickness is stacked on both surfaces, and the temperature is 170 ° C. and the pressure is 40 kg / cm by a heat medium oil press.
² was heated and pressed for 70 minutes to obtain a multilayer printed wiring board. Etching the copper foil on the surface by a predetermined method,
A terminal (pad) to be connected to the primary side connection portion of the TAB was formed. Thermal expansion coefficient (T) of the multilayer printed wiring board in the plane direction
Tables 1 to 3 show the measurement results of the drill wear rate at the time of drilling. The drill wear rate is φ
Using a drill of 0.4mm, rotation speed 75000rpm,
This is a measurement value after 4000 holes are drilled under the condition of a speed of 1.2 m / min. A terminal arranged on the side edge of the liquid crystal panel glass substrate is prepared in advance by connecting the secondary side connection portions of twelve slim TABs via an ACF (anisotropic conductive film). The primary connection portion of the slim TAB was connected collectively to the terminals of the multilayer printed wiring board having the same length as the side edge of the liquid crystal panel glass substrate via the ACF.

In a liquid crystal display device in which the liquid crystal panel glass substrate and the multilayer printed wiring board are connected to each other via TAB and assembled, the measurement results of the warpage of the assembled multilayer printed wiring board are shown in Tables 1 to 3. Tables 1 to 3 show the results of counting the disconnection rate of the TAB copper foil circuit after assembling and after a thermal shock test (-55 ° C .: 30 minutes and 125 ° C .: 500 minutes with 30 minutes as one cycle). Show. TAB
Is the ratio of the number of disconnections to the ten assembled liquid crystal display devices.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

From Tables 1 to 3, it can be seen that by setting the coefficient of thermal expansion of the multilayer printed wiring board to 13 ppm / ° C. or less, the warpage of the multilayer printed wiring board assembled in the liquid crystal display device becomes extremely small. Further, the resin constituting the multilayer printed wiring board by impregnating the glass woven fabric has an elastic modulus of 200 kg / mm ² or less, so that the thermal expansion coefficient of the multilayer printed wiring board is further reduced.
It can be seen that it is more convenient in preventing the occurrence of cracks in the copper foil circuit.

[0017]

As described above, in the method of manufacturing a liquid crystal display device according to the present invention, first, the secondary connection portion of the TAB is fixedly connected to the terminals arranged on the side edges of the liquid crystal panel glass substrate. Next, when the primary connection portion of the TAB is fixedly connected to the terminals arranged on the multilayer printed wiring board, the coefficient of thermal expansion of the multilayer printed wiring board is 13 ppm.
By controlling the temperature to / ° C or lower, the warpage of the multilayer printed wiring board can be reduced after the liquid crystal display device is assembled and in the subsequent cooling and heating cycle. As a result, disconnection of the TAB copper foil circuit can be eliminated.

[Brief description of the drawings]

FIG. 1 is an explanatory plan view of a TAB that connects a liquid crystal panel glass substrate and a printed wiring board.

FIG. 2 shows a liquid crystal panel glass substrate and a printed circuit board as T
It is a perspective view explaining the state connected via AB.

[Explanation of symbols]

 1 is an LSI 2 is a secondary connection 3 is a primary connection 4 is a liquid crystal panel lath substrate 5 is a printed circuit board 10 is a TAB

Continuation of front page (72) Inventor Hiroyuki Yamanaka 2-8-7 Nihonbashi Honcho, Chuo-ku, Tokyo Shin-Kobe Electric Machinery Co., Ltd.

Claims (3)

[Claims] 1. A multi-layer printed wiring board having a glass woven fabric impregnated with a resin as an insulating layer and a liquid crystal panel glass substrate are formed by TA.
B, wherein the secondary connection portion of the TAB is fixedly connected to the terminal arranged on the side edge of the liquid crystal panel glass substrate, and then the primary connection portion of the TAB is connected to the multilayer print. The terminals arranged on the wiring board are fixedly connected to each other, and the multilayer printed wiring board has a coefficient of thermal expansion of 13p.
A method for manufacturing a liquid crystal display device, wherein a liquid crystal display device having a pm / ° C. or lower is used. 2. The glass yarn constituting the glass woven fabric has a coefficient of thermal expansion of 4 ppm / ° C. or less and an elastic modulus of 7000 kg / mm.
^{2. The} method according to claim 1, wherein the number is ² or more. 3. The resin impregnated in the glass woven fabric has an elastic modulus of 20.
The glass yarn constituting the glass woven fabric has a coefficient of thermal expansion of 6 ppm / ° C. or less and an elastic modulus of 70 kg / mm ² or less.
2. The method for producing a liquid crystal display device according to claim 1, wherein the amount is at least 00 kg / mm ² .