JPH0369918A - Manufacture of liquid crystal panel - Google Patents

Abstract

PURPOSE:To maintain the uniformity of a film thickness as it is by spreading the orienting material dropped onto a substrate to the entire area of the surface by rotating the substrate, then drying the orienting material film during rotation of the substrate surface. CONSTITUTION:The substrate 1 to be coated with the orienting material is imposed on a spin head 6 and a heater 7 is provided on the rear surface of the spin head 6. The spin head 6 is kept heated by a heater 7. After the orienting material 2 is dropped onto the substrate 1, the substrate 1 is attracted by a vacuum and is fixed to the spin head 6, then the substrate is rotated. The film 2' on the substrate 1 is dried when the rotation of the spin head 6 is thereafter stopped. The back flow of the excess liquid in the peripheral edge part of the substrate is obviated in such a manner even if the rotation is stopped. The orienting material film maintains the film thickness at the time of the substrate rotation as it is. The uniformity of the film thickness is thus maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a liquid crystal panel, and particularly to a method for forming an alignment film.

As liquid crystal panels become larger, requirements for uniformity of alignment films, display cell thicknesses, etc. are becoming increasingly strict.

3. Detailed description of the invention [Summary] Regarding a method for manufacturing a liquid crystal panel, particularly a method for forming an alignment film, when forming an alignment material film by a spin coating method, [Prior art] Alignment film for a liquid crystal display panel is made of organic polymer material such as polyimide.

Formation of an alignment film has long been a process of applying an alignment material such as polyimide to the surface of a substrate using a spin coating method, pre-drying it at a relatively low temperature, and then curing it by applying a high-temperature heat treatment. It was done at

The above-mentioned pre-drying is a process performed not only to dry the solvent but also to prevent moisture adsorption and dust adhesion. This step is performed after the substrate is removed from the spinner after the spin coating method using a spin coating device called a spinner is completed.

[Problem to be solved by the invention]

However, in the above conventional method, as shown in FIG. 2(a), the alignment material 2 dropped onto the substrate mounted on the spin head 6 is moved to the peripheral edge side of the substrate 1 by the rotation of the head 6 (see arrow B). (see arrow A), and most of the excess liquid is shaken off. However, the surface tension and centrifugal force are balanced in a part of the liquid, and the liquid does not fly away, forming a raised liquid pool 4 at the peripheral edge as shown in the figure.

During rotation, the applied alignment material film 2 is applied to the substrate 1 other than the peripheral edge.
Although the thickness of the alignment material film 2 is uniform, the alignment material film 2 is still not dry when the rotation is stopped.
As shown in FIG. 2(b), the liquid in the liquid pool 4 tends to back up (see arrow C), resulting in a loss of uniformity in film thickness.

Therefore, in the conventional method of forming an alignment film, concentric thickness unevenness occurs in the film thickness, which causes deterioration in display quality.

In the present invention, when forming an alignment material film by a spin coating method,
The purpose is to maintain uniformity of film thickness during substrate rotation.

[Means to solve the problem]

In the present invention, when forming an alignment material film on the substrate surface by spreading the alignment material dropped onto the substrate over the entire surface of the substrate by rotating the substrate, the alignment material film is dried during the rotation of the substrate.

[For production]

Since the alignment material dries during spin coating, the alignment material film has lost its fluidity at that point. Therefore, even if the rotation is stopped, the excess liquid on the peripheral edge of the substrate does not flow back, and the alignment material film maintains the same thickness as when the substrate was rotated, so that the uniformity of the film thickness can be maintained.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

A substrate 1 to be coated with an alignment material is placed on a spin head 6. A heater 7 is provided on the back side of this spin head, and the spin head 6 is heated to approximately 40° C. by the heater 7.

After dropping polyimide 2 as an alignment material onto the substrate 1, the substrate 1 is vacuum-adsorbed and fixed to the spin rad 6.
) Rotate at 00Orp. After about 60 seconds, the rotation of the spin head 6 is stopped. Since the polyimide film 2' on the substrate 1 is already dry at this time, there is no need to perform preliminary drying after this, and curing is immediately performed at a high temperature of about 250°C.

As a result, the obtained alignment film maintains its shape during head rotation. Therefore, a fairly uniform film thickness is maintained except for the liquid pool 4 at the peripheral edge of the substrate 1.

Since this liquid pool 4 is away from the display section, it has no bearing on the display. Further, in a subsequent step, the alignment film on the peripheral edge of the substrate 1 is removed in order to expose the ends of the electrodes, so there is no problem even if the liquid pool 4 remains in this step.

After this, the liquid crystal display panel may be charged according to the usual process, such as rubbing treatment and the like.

〔Effect of the invention〕

As explained above, according to the present invention, the thickness distribution of the alignment film formed by spin coating can be made uniform, so that a liquid crystal panel without display unevenness can be manufactured.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention, and FIG. 2 is an explanatory diagram of problems in the prior art. In the figure, 1 is the substrate, 2 is the alignment material, 2'' is the alignment material film, 4 is the liquid reservoir, 6 is the spin head, and 7 is the heater.

Claims (2)

[Claims] (1) When spreading the alignment material dropped onto the substrate over the entire surface of the substrate by rotating the substrate to form an alignment material film on the substrate surface, a step of drying the alignment material film during the substrate rotation is performed. A method for manufacturing a liquid crystal panel, comprising: (2) A method for manufacturing a liquid crystal panel according to claim 1, characterized in that a heating means is attached to the rotating table on which the substrate is mounted, and the alignment material film on the surface of the substrate is dried by the heating means while the substrate is being rotated. .