JP4423611B2 - Glass substrate for flat panel display - Google Patents

Description

  The present invention relates to an array substrate material for a flat panel display, a glass substrate used as a counter substrate material thereof, and a manufacturing method thereof.

  Conventionally, a large amount of rectangular plate glass having a thickness of about 0.3 to 3.0 mm has been used as a glass substrate for a flat panel display. In particular, in recent years, the market for flat panel displays using thin-film electric circuits such as α-Si TFT (Amorphous-Si Thin Film Transistor) liquid crystal displays is rapidly expanding.

  By the way, the recent flat glass substrate for flat panel display is required to be large. That is, the size of the display, which is the final product, is mainly about 12 inches diagonal, but a plurality of display substrates are manufactured from a large glass substrate for the purpose of reducing the manufacturing cost of the display substrate and improving the throughput. Multi method is adopted. In other words, after a plurality of circuit patterns are formed on a large glass substrate (glass base plate) formed by a glass manufacturer, the glass substrate is divided and cut for each circuit pattern to produce a plurality of display substrates. These substrates are used as an array substrate that becomes a back substrate of a display. Similarly, the counter substrate (front substrate) of the array substrate employs a production method in which a plurality of patterns are formed on a large glass substrate and then divided and cut.

For this reason, the size (vertical and horizontal dimensions) of the conventional glass substrate was 300 × 400 mm or 370 × 470 mm, but recently, a glass substrate having a size of 550 × 650 mm or larger is required. It is becoming.
JP-A-5-163032 JP-A-5-339021 JP-A-9-278470

  As described above, recently, the glass substrate for flat panel display has been increased in size, but with this, there has been a problem that the glass substrate is deformed after the glass substrate is divided and cut. Yes.

  For example, on a glass substrate used as an array substrate of a liquid crystal display, a circuit pattern in which a thin film electric circuit, other various metal films, an insulating film, and the like are combined is formed. Although a pattern is formed, if the glass substrate on which such a pixel pattern is formed is deformed after being divided and cut, each pixel pattern deviates from the intended design, and the circuit pattern of the array substrate and the color filter substrate This is a big problem because it does not match the pattern of this and may lead to a fatal defect such as a display defect of the liquid crystal display as the final product.

  An object of the present invention is a glass substrate for a flat panel display, in which even a large plate glass is less deformed after split cutting, and the pattern does not deviate from the intended design and display defects do not occur. It is to provide a manufacturing method.

As a result of repeating various experiments to achieve the above object, the inventors of the present invention are deformed after the glass substrate is divided and cut, because a large residual stress is generated in the plane direction of the glass substrate. It was found that by suppressing the residual stress in the direction to a certain value or less, deformation after the divided cutting of the glass substrate was suppressed, and the present invention was proposed. That is, the glass substrate for flat panel display of the present invention is characterized in that the vertical dimension is 400 mm or more, the horizontal dimension is 500 mm or more, and the residual stress in the plane direction is 5 kg / cm ² or less.

Moreover, the glass substrate for flat panel displays of the present invention is characterized by having a vertical dimension of 550 mm or more and a horizontal dimension of 650 mm or more.

  Moreover, the glass substrate for flat panel displays of this invention is used for a liquid crystal display.

The glass substrate for flat panel displays of the present invention can be produced by performing temperature control so as to reduce the temperature distribution generated in the plane direction in the cooling step after forming the plate glass.

The glass sheet is preferably formed by any one of a float method, an overflow down draw method, and a slot down draw method.

Since the flat panel display glass substrate of the present invention has a residual stress in the plane direction of 5 kg / cm ² or less, even if the glass substrate is divided and cut for each pattern after the pattern is formed on the glass substrate, the glass substrate is deformed. Few. Therefore, it is particularly useful for a glass substrate for display having a vertical dimension of 400 mm or more and a horizontal dimension of 500 mm or more, which tends to increase the residual stress at the peripheral edge.

  The mechanism by which residual stress occurs in the glass substrate for flat panel displays is as follows.

  As a general industrial method for forming this type of glass substrate, a float method, an overflow down draw method, a slot down draw method, and the like are known. When the plate glass is cooled, a temperature distribution is generated in the thickness direction and some temperature distribution is also generated in the plane direction. As a result, non-uniform residual stress is generated.

  It is the residual stress that occurs mainly in the plane direction of the glass substrate that affects the deformation after cutting. If the cooling rate of the peripheral edge is faster than the vicinity of the center of the glass substrate, or conversely, Residual stress is generated in the vicinity of the peripheral portion when the cooling rate of the peripheral portion is lower than that in the vicinity of the center. When a glass substrate having such a residual stress in the planar direction is divided and cut, it tries to release the stress by deformation.

According to the knowledge of the present inventors, the residual stress in the plane direction increases in proportion to the size of the glass substrate. For example, in the case of a glass substrate having a vertical dimension of 400 mm or more and a horizontal dimension of 500 mm or more, the residual stress in the peripheral portion. May be 20 kg / cm ² or more. However, if the residual stress in the plane direction of the glass substrate is 5 kg / cm ² or less, even if it is divided and cut, no significant deformation will occur.

  Next, a method for producing a glass substrate for a flat panel display according to the present invention will be described.

  First, one method is a method of performing temperature control so that the temperature distribution generated in the plane direction is made as small as possible in the cooling step after forming the glass sheet.

  Another method is to form, cool, and cut a sheet glass by a normal method, and then place it on a setter made of a low expansion crystallized glass plate or a ceramic plate having excellent flatness and then anneal it. This is a method of reducing the residual stress in the plane direction generated in the plate glass.

However, even if the glass substrate is annealed by a normal method, it is difficult to uniformly heat and cool the entire surface of the glass substrate, and in particular, the residual stress at the peripheral edge of the glass substrate near the furnace wall of the annealing furnace tends to increase. Therefore, annealing is performed by one of the following methods.

  (A) A method in which a plate glass larger than a predetermined size is prepared in advance and annealed, and then the peripheral portion of the glass substrate is cut off to obtain a glass substrate having a predetermined size. However, in this method, since the peripheral part of a glass substrate will be discarded, there exists a problem that the production efficiency of glass falls.

  (B) A method of uniformly annealing a glass substrate by using a large heat-resistant setter having a vertical dimension and a horizontal dimension that are 50 mm or more longer than the vertical dimension and the horizontal dimension of the glass substrate.

  (C) A method of uniformly annealing a glass substrate by disposing a heat-resistant dummy setter in the vicinity of the heat-resistant setter on which the glass substrate is placed.

  In the case of annealing, a continuous annealing furnace or a batch electric furnace can be used, but it is desirable to use a continuous annealing furnace in view of productivity.

  Hereinafter, the glass substrate for flat panel displays of this invention is demonstrated in detail based on an Example and a comparative example.

First, glass raw materials are prepared so that the composition of SiO ₂ 55%, B ₂ O ₃ 10%, Al ₂ O ₃ 10%, RO 25% by weight%, melted at 1580 ° C. for a predetermined time, and then slotted down. 36 sheets of alkali-free glass substrates for α-Si TFT liquid crystal displays having dimensions of 550 × 650 × 0.7 mm were formed by molding using a draw method and cutting.

Next, these glass substrates are placed one by one on a plate-like heat-resistant setter (Neoceram N-0 manufactured by Nippon Electric Glass Co., Ltd.) and placed in an annealing furnace. By changing, 12 glass substrates having a residual stress in the planar direction of 20 kg / cm ² (A group), 12 glass substrates having a residual stress in the planar direction of 10 kg / cm ² (Group B), residual in the planar direction Twelve glass substrates (C group) having a stress of 4 kg / cm ² were produced.
Thereafter, as shown in FIG. 1, four circuit patterns 11 are formed on each glass substrate 10, and then, for each circuit pattern 11, the glass substrate 10 is arranged in four arrays along two cutting lines 12 and 12. The substrate was divided and cut, and the maximum deviation from the normal position of the circuit pattern 11 on these array substrates was measured. The results are shown in Table 1.

  As is clear from Table 1, the group A array substrate had a large circuit pattern deviation of 6 to 8 μm, but the group C array substrate hardly caused the circuit pattern deviation. A correlation was recognized between the magnitude of the residual stress in the planar direction of the array substrate and the amount of dimensional deviation after cutting.

  In addition, said residual stress was measured based on the Senarmon method using Toshiba distortion tester SVP-100.

  As for the amount of displacement of the array substrate, an undeformed color filter substrate having the same size as the array substrate is prepared as the counter substrate, and the array substrate 13 is superimposed on the color filter substrate 14 as shown in FIG. The length (L) of the portion with the largest deviation between the circuit pattern 15 on the array substrate 13 and the pattern 16 formed on the color filter substrate 14 is measured with a microscope.

It is a top view which shows the glass substrate in which four circuit patterns were formed. It is a schematic explanatory drawing which shows the state which piled up the array board | substrate on the color filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Glass substrate 11, 15 Circuit pattern 12 Cutting line 13 Array substrate 14 Color filter substrate 16 Pattern formed on color filter substrate

Claims (3)

A glass substrate for a flat panel display , wherein a vertical dimension is 400 mm or more, a horizontal dimension is 500 mm or more, and a residual stress in a plane direction is 5 kg / cm ² or less. The glass substrate for a flat panel display according to claim 1, wherein the vertical dimension is 550 mm or more and the horizontal dimension is 650 mm or more. Claim 1 or 2 flat panel glass substrate for displays as claimed, characterized in that it is used in a liquid crystal display.

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