JP3213117B2 - Liquid crystal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting method for directly mounting a driving IC chip for driving a liquid crystal on a liquid crystal panel .
The present invention relates to a mounting structure of a so-called COG (chip-on-glass) type liquid crystal device .

[0002]

2. Description of the Related Art A liquid crystal display which is often used as a liquid crystal device in the following.
Explanation will be made using the display panel. Conventionally, a method of connecting a liquid crystal display panel to a driving IC chip has been put into practical use, and includes a TAB (tape outer bonding) method, a COB (chip-on-board) method, a COG method, and the like.

With the recent market demand for liquid crystal devices or liquid crystal display panels shifting to higher pixel density, color display, and lower cost, it is important to establish a high-density mounting technology. C
The OG method is most suitable for these requirements, and further improvement in reliability quality is indispensable.

[0004] In the COG method, the processing method is different depending on the type of the connecting member. Among these, the method using a conductive adhesive using a resin as a binder for the connection member is the simplest and is suitable for mass production.

FIG. 2 is a schematic sectional view showing a liquid crystal display panel structure by the COG mounting method. Electrode 50, the peripheral portion of the glass substrate 10 and 40 of a pair of arranged electrodes 60 sealed with the sealing member 30, in the liquid crystal display panel obtained by sandwiching between glass substrate 10 and the glass substrate 40, the liquid crystal The electrode 50 on the display panel substrate is an anisotropic conductive film 90.
Are joined to the FPC 100 to form a power supply and a signal input terminal. A conductive adhesive 8 using a resin as a binder;
At 0 and 110, the driving IC 70 is joined as a power supply and a signal input / output terminal of the electrode 50 formed on the glass substrate 10 of the liquid crystal display panel.

[0006] When the IC 70 is bonded to the electrode 50 of the liquid crystal display panel, the conventional manufacturing method which is most excellent in mass productivity is a paste-like conductive adhesive 80 or 1 using a resin as a binder.
10, a screen printing method to the electrode pattern terminal portion on the substrate 10 of the glass of the liquid crystal display panel, after patterning by a dispenser method, after aligning the bump portion which is formed on the IC70 of at junction device Crimp. Thereafter, the electrodes 50 and the bumps of the IC 70 are joined by conductive adhesives 80 and 110 by heat treatment. The method using the conductive adhesive is suitable for mass production and is excellent in economy.

[0007]

The quality of the liquid crystal display panel obtained by the conventional manufacturing method is caused by a poor connection between a driving IC chip and a terminal for joining the liquid crystal display panel in a mounting process. It has important quality problems related to the electrical continuity reliability of the above joints, such as the occurrence of a large number of display defects that occur, the lack of durability in accelerated tests intended for outdoor or on-vehicle use, etc. ing.

As a result of the display defect failure mode analysis, it has been found that the joints that cause electrical connection failure are concentrated on the liquid crystal display panel electrode joints, and that the conductive adhesive is all peeled off and raised. Therefore, the present inventor has discovered that the above-mentioned problem is caused by insufficient adhesion between the liquid crystal display panel electrode and the conductive adhesive.

An object of the present invention is to provide a structure of a liquid crystal display panel for solving the above problems and improving the reliability of COG mounting without changing the conventional manufacturing method.

[0010]

In order to solve the above-mentioned problems, the present invention provides at least an adhesive and a conductive material on a glass substrate.
With a drive IC directly mounted with conductive adhesive mixed with
In the crystal apparatus, the conductive adhesive is
Upper electrode, insulating film pattern-coated on said electrode
Bonding to the layer and the low thermal expansion glass under the electrode
It is characterized by.

Further , the coefficient of thermal expansion of the glass substrate
The thermal expansion coefficient of the silicon wafer of the operating IC should be
It is characterized by having.

The glass substrate has a coefficient of thermal expansion of 5
Low thermal expansion glass of 5 × 10E (-7) / ° C or less
And features.

[0013] Further , the conductive adhesive is at least an air.
Consists of a oxy resin binder and a silane coupling agent
It is characterized by the following. In addition, the epoxy resin binder
Is a thermosetting epoxy resin using acid anhydride as a curing agent
It is a fat. Further, the insulating film has a thickness of 20 to
SiO2 having a thickness of 1500 angstroms m
(Silicon oxide) layer.

[0014]

The object is to improve the adhesive strength between the conductive adhesive and the electrode portion of the liquid crystal display panel. The factors that lower the adhesive strength are divided into two items, and the effect on each will be described.

[0015] Recovery of insufficient absolute amount of interfacial bonding force of conductive adhesive. As a countermeasure, as a result of evaluation of various materials, a conductive adhesive using a heat-curable epoxy resin as a binder using an acid anhydride, which is particularly excellent in adhesiveness to glass, as a curing agent should be used.

Insufficient durability of the conductive adhesive due to external stress such as a thermal shock applied secondarily and a decrease in interfacial bonding force due to a water permeation phenomenon. As a countermeasure, drive IC
A glass material having a coefficient of thermal expansion close to that of a silicon wafer used for chips is selected to minimize the occurrence of displacement stress caused by thermal deformation. The decrease in the bonding force due to the water permeation phenomenon is prevented by forming a chemical bond between the epoxy adhesive and the glass by the silane coupling agent.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

[0018] glass substrates in the liquid crystal display panel in FIG. 1 10, 40 (see Figure 2 glass substrate 40), glass
When the coefficient of thermal expansion of the substrate is 55 × 10E (−7) / ° C. (55
The electrodes 60 and 50 were formed by using a low-concentration glass (for example, borosilicate glass) having a low coefficient of thermal expansion of 10 −7 / ° C. or less, and a transparent conductive film formed by an evaporation method as an electrode film by a photoetching method. Thereafter, a 100 .ANG.-thick SiO2 film is formed on the electrode 50 by low-temperature sputtering. Thereafter, the conductive adhesives 80 and 1
10 and SiO2 of the anisotropic conductive film 90 are removed by photoetching to form electrical connection points. Thereafter, after performing an alignment treatment, the electrodes of the glass substrates 10 and 40 are attached to each other with a sealing member 30 as an epoxy sealing agent so as to face each other, and then the liquid crystal substance 20 is injected and sealed.
Create a liquid crystal display panel.

FIG. 2 illustrates the operation of the present invention.
FIG. 2 shows a partially enlarged view of a junction between an IC 70 and an electrode 50 of a liquid crystal display panel in FIG. 1. In FIG. 2, the IC 70 and the electrode 50 of the liquid crystal display panel are connected by a conductive adhesive 80 containing a silane coupling agent and using an epoxy resin as a binder.
Connect through. The connection portion 51 has a function of obtaining electrical connection with the conductive adhesive 80. On the other hand, an SiO2 film layer 120 obtained by pattern-coating on the electrode 50 in advance.
And a bonding point 121 with the conductive adhesive 80 and the glass substrate 10 using the low thermal expansion glass and the conductive adhesive 8
The bonding point 11 with 0 can provide an adhesion reinforcing effect by the silane coupling agent contained in the conductive adhesive. As described above, in order to increase the reliability of the electrode connection portion of the conductive adhesive, the electrode portion is provided with an electrical connection point and an adhesion reinforcement point for connection.

In FIG. 2, an acid anhydride obtained by adding 0.5 to 2.0% by weight of a glycidyl silane coupling agent to the electrical connection points 11, 51 and 121 of the liquid crystal display panel obtained as described above is added. A conductive adhesive 80 using an epoxy resin as a curing agent as a binder is printed on a metal screen. After the printing shape is adjusted by temporary heating, it is positioned and aligned with the bumps of the driving IC 70, and is pressed and contacted.

The liquid crystal display panel obtained as described above allows connection of high-density terminals up to approximately 324 bumps of the driving IC 70, and connection reliability is greatly improved in various durability tests. A product that can fully satisfy the standards for liquid crystal display panels for in-vehicle and outdoor use was obtained.

[0022]

According to the present invention, a driving IC chip is provided.
Glass whose thermal expansion coefficient approximates the silicon wafer used
Stress caused by thermal deformation due to selection of material
This has the effect of minimizing generation. this
As a result, external stress such as thermal shock applied secondarily
Can reduce insufficient durability of the conductive adhesive
Was.

In addition, epoxies can be used with silane coupling agents.
By forming a chemical bond between the adhesive and the glass
Can prevent a decrease in bonding strength due to the phenomenon of water permeability.
Has the effect. As a result, the interfacial connection
Conductive adhesion due to effects such as a decrease in resultant force Insufficient durability of the agent
Could be improved.

By using the structure according to the present invention at the connection point with the driving IC chip using the conductive adhesive, the liquid crystal having a high mounting portion retention and high reliability can be obtained without changing the production method.
The effect of obtaining the device was obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a connection portion between a driving IC chip obtained by the present invention and a liquid crystal display panel electrode.

FIG. 2 is a schematic cross-sectional view illustrating a structure of a liquid crystal display panel using a COG mounting method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Glass substrate 20 Liquid crystal layer 30 Seal member 40 Opposing glass substrate 50 Electrode 60 Electrode 70 IC 80 Conductive adhesive 90 Anisotropic conductive film 100 FPC 110 Conductive adhesive 120 SiO2 film 11, 51, 121 Connection point

Claims (6)

(57) [Claims] 1. A glass substrate comprising at least an adhesive and a conductive material
With a drive IC directly mounted with conductive adhesive mixed with
In the crystallizing apparatus, the conductive adhesive is used for the electrode on the glass substrate and the electrode.
An insulating film layer pattern-coated on the extreme, and the electrode
Liquid crystal device characterized by a configuration that adheres to the low thermal expansion glass below
Place. 2. The method according to claim 1 , wherein the coefficient of thermal expansion of the glass substrate is determined for the driving.
Make sure that the coefficient of thermal expansion of the silicon wafer of the IC is
The liquid crystal device according to claim 1, wherein: 3. The glass substrate has a thermal expansion coefficient of 55 ×.
Low thermal expansion glass of 10E (-7) / ° C or less
The liquid crystal device according to claim 1, wherein: 4. The method according to claim 1, wherein the conductive adhesive is at least epoxy resin.
Consist of resin binder and silane coupling agent
The liquid crystal according to any one of claims 1 to 3, wherein
apparatus. 5. The method according to claim 1, wherein the epoxy resin binder is an acid anhydride.
It is a thermosetting epoxy resin that uses
The liquid crystal device according to claim 4, wherein: 6. The insulating film according to claim 1, wherein said insulating film is 20 to 1500 angstroms.
A SiO2 (silicon oxide) layer having a thickness of ROHM m
The method according to any one of claims 1 to 4, wherein
Liquid crystal device.