Introduction of production technology of liquid crystal glass substrate

Liquid crystal glass substrate is an important part of liquid crystal display, which has high commercial value. The produc

Introduction of production technology of liquid crystal glass substrate

Liquid crystal glass substrate is an important part of liquid crystal display, which has high commercial value. The production technology of liquid crystal glass substrate is very high, which requires the liquid crystal glass substrate to be very flat, and it is a very technical work. There are three main production processes for liquid crystal glass substrates. Different production processes of liquid crystal glass substrates have different advantages and characteristics. The following small series will introduce you to the production process of LCD glass substrate.

Production technology of liquid crystal glass substrate

There are three main technologies for producing glass substrates for flat panel displays, namely, float method? Technology), flow hole downward drawing method (groove? Come down? Draw) and overflow melting method (overflow? Fusion? Technology). Float will produce scars and bumps on the surface due to horizontal stretching, which requires surface polishing, so the investment is high, but it has the advantages of producing wide glass products (width can reach 2.5 meters) and large capacity (about 6.5438+10,000 square meters/month). The overflow melting method has the advantages of controllable surface characteristics, no grinding and simple process, and is especially suitable for producing ultra-thin flat glass with a thickness less than 2mm. However, the width of the produced glass is limited below 1.5m, so the production capacity is small. Float can produce glass substrates suitable for various flat panel displays, and overflow melting method is only used to produce TFT-? Liquid crystal glass substrate. Only the above three technologies are described as follows:

Floating method:

As the most famous flat glass manufacturing technology at present, this legal system transports molten glass slurry from the melting furnace to the liquid tin bed. Because of its low viscosity, the thickness of glass can be controlled by baffles or pull rods. With the increase of the distance flowing through the tin bed, the glass slurry gradually solidifies into flat glass, and then the solidified glass plate is led out by the guide wheel, and then the post-treatment processes such as annealing and cutting are carried out.

When producing ultra-thin flat glass by float method, the feeding amount of glass slurry should be controlled at a low level. First, the glass ribbon entering the tin bed should be cooled to about 700℃, and the viscosity of the glass ribbon at this time is about 108 poise (poise; 1 berth =? 1g/cm sec? ), and then the glass paste floating on the liquid tin is pulled by an edge-drawing roller, and after being stretched outwards, the glass ribbon is heated to 850℃, and the roller of the conveyor belt exerts external force to pull, so that the ultra-thin flat glass is made by the floating method, as shown in Figure 3.

The floating method adopts horizontal stretching method, and it is easier to meet the requirements of annealing by stretching the production line horizontally. The main reason why float technology can't be widely used to produce ultra-thin flat glass with thickness less than 2mm is that it can't reach the required economic scale. For example, the daily output of floating technology can almost meet the consumption of Taiwan Province province market for one month at present; If the float technology is used to produce ultra-thin flat glass, it is usually produced in a discontinuous day pool, so the optimization of pool and kiln design is very important.

Downward stretching method of flow hole:

As far as ultra-thin flat glass for flat panel display is concerned, many manufacturers use the flow hole pull-down technology to introduce low-viscosity homogeneous glass slurry into platinum alloy to make flow hole bushing (? Slot? Bushing? ) In the tank, the thickness of glass is controlled by gravity, pull-down force and die size, in which temperature and nozzle size determine the glass output, nozzle size and pull-down speed determine the glass thickness, and temperature distribution determines the glass warpage. Ultra-thin flat glass is drawn by orifice drawing technology, as shown in Figure 4.

Downhole drawing process can produce 5? Every day. ~? 2? 0 metric ton thickness 0.0? 3? ~? 1. 1㎜ ultra-thin flat glass, because platinum metal can not bear high mechanical stress, platinum alloy is generally used. However, due to the deformation of the flow hole under external force, its shortcomings are uneven thickness and the surface flatness can not meet the requirements of the specification.

The flow hole downdraw method must be annealed in the vertical direction. If it turns to the horizontal direction, it may increase the contact between the glass surface and the roller and the warping caused by horizontal transportation, which will greatly increase the reject rate. Such concerns make it necessary to adopt high-altitude design when building the furnace, and at the same time, the height required for annealing must be accurately considered, which greatly increases the engineering difficulty and is also reflected in the cost of building the factory.

Overflow melting method:

It uses a long melting pump (Fusion? Pump), which transports the molten glass slurry to the center of the melting pump, and then combines the two spilled glass slurries at the lower part of the pump to form ultra-thin flat glass through overflow.

The use of this molding technology also depends on heavy molds, so the mold of the melting pump is also faced with the problems of deformation due to mechanical stress, keeping the levelness of the melting pump and how to pump the molten glass slurry into the melting pump stably. Because the thickness and surface quality of ultra-flat glass made by overflow melting method depend on the amount, stability, levelness of glass slurry, surface properties of pump and the amount of glass pumped.

Melt overflow technology can produce ultra-thin glass substrates with double original glass surfaces. Compared with the float method (which can only produce a single original glass surface) and the flow hole pull-down method (which can not produce the original glass surface), it can avoid post-treatment processes such as grinding or polishing. At the same time, in the manufacturing process of flat panel display, it is not necessary to pay attention to the difference of glass surface properties caused by having different original tin surface and liquid tin surface at the same time, or contacting with grinding media, which has become the mainstream of ultra-thin flat glass molding.

Because alkali-free glass has a special composition formula, it has very strict standards and specifications in thermal stability, mechanical, electrical, optical, chemical and other characteristics, appearance size, surface flatness and so on. Its production line adjustment and learning time are long, and the technical threshold for new manufacturers to enter the industry is high.

What are the production processes of liquid crystal glass substrates? What are the specific contents of these production processes of liquid crystal glass substrates? These small series have been introduced in detail. There are many manufacturers of LCD glass substrates in China. This is an economical production line with high economic value. The quality of LCD glass substrate will determine many things. If you are interested, you can learn more about the LCD glass substrate.

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