Rebirth of Northland Technology

The technical difficulty of TFT-LCD production is completely different from that of semiconductor production.

Semiconductor production lines, generally speaking, the earlier the production line, the easier it is to absorb technology.The LCD is just the opposite!

The first generation of TFT production line is the king of difficulty!

This is the fundamental reason why China lost two somersaults on the first-generation production line.

When have you heard that the production line is completed but cannot be put into production?Is this still a production line?

But it is everywhere that stumbles on the first-generation TFT line.This is the case in the mainland, the Americans, the Koreans, and Taiwan.

Regarding the production difficulty of the first-generation production line, a senior manager of Toshiba's marketing department at the time was quoted as saying,

"It was like looking for a working LCD screen in a pile of garbage."

It took a full four years for Japanese companies that first entered mass production to gradually increase the yield from less than 10% to 80%.

The production line of DTI (a joint venture between IBM and Toshiba) has had a low yield since it was put into production.As of March 1992, only 4,200 tablets were produced per month on average.

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The biggest reason why the production of the first generation TFT-LCD is so difficult is the cleanliness requirements of the production environment.

Due to the TFT production line and the semiconductor production line, a large part of the process overlaps, but the accuracy requirement of LCD is relatively low (10 microns).

Therefore, these manufacturers take it for granted that the LCD production environment will have relatively low environmental requirements (the same as small LCDs).

But the actual situation is just right.Due to the larger area of ​​the LCD, the probability of being contaminated by dust increases.In addition, in the process of wafer production.A wafer can be cut into hundreds or thousands of chips.Several of these chips are contaminated, it doesn't matter, just eliminate them.

But LCD, there is only one, it cannot be eliminated!

The second reason is special equipment.

The equipment currently used by various manufacturers is mainly general equipment used to manufacture solar cells.

The production of solar panels is not sensitive to the effects of dust particles.The quality of products processed with general equipment cannot be guaranteed.

After the cause was found, the major LCD manufacturers could only seek help from equipment manufacturers (American Applied Materials) for targeted rectification.

After the new generation of LCD special equipment was launched (October 1993), the yield rate of LCD (second generation line) has risen to 80% since 1994.(The equipment manufacturer claims to be 90%)

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After the first generation of technology, starting from the second generation, the difficulty of TFT-LCD should be easy, right?

In fact, it is still difficult!

A circumstantial evidence about the difficulty of early LCD production technology:

The first mass production line of TFT was born in 1989, and its (economic) size was 10 inches.But the time has come to 2000, and this size has only reached 17 inches.

In ten years, the size of LCD has only expanded by 7 inches!

The following are the economic dimensions of mainstream production lines at that time.

The first generation line (1991), the mainstream liquid crystal display in the market, the size is 8-10 inches.

The 3rd generation line (1996), the size is 12 inches.

The 4th generation line (2000), the size is 17 inches.

Here is a concept, to introduce, economic size.It refers to the cut size of the most valuable product produced on the same glass substrate.

For example, on a glass substrate, a 10.4-inch display can be produced.Another option is to produce a 14-inch display.

In the early liquid crystal market, there was such a rule that the price doubled.In other words, the price of a 17-inch monitor is four times that of a 15-inch monitor.

According to this rule, the price of 14 inches should be 16 times that of 10 inches.Why is 10 inches an economic size?It is because the yield of 14 inches is too low, as low as 16 times the price, and the cost cannot be recovered!

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Another evidence on the technical difficulty of early LCD production.

Before 2000, LCD monitors sold on the market had an indicator called "dead pixel rate"!

This indicator means that dead pixels are allowed on a screen.As long as the number of dead pixels is less than a certain number, it is considered a qualified product!(Less than 5 counts as qualified, less than 2 counts as superior product!)

This shows that with the production process at that time, the appearance of dead pixels is supposed and inevitable!

And this dead pixel, after 2000, after the 5th generation production line, it quickly disappeared!

Whether you buy a laptop, a desktop monitor, or a TV, who has seen a broken pixel?

Why is there such a product as Plasma plasma TV in the early 21st century.Because in those days, no one believed that LCD monitors could be so big!

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But this conclusion was quickly beaten by the 5th generation line.

Before the 5th generation line, the main market for LCD monitors was only notebook computers and desktop monitors, but after 2000, the main market for LCD monitors became TVs.

The size of the liquid crystal has also begun a large-scale growth process.

The economic size of the 5th generation line (2002) comes to 27 inches!, The 6th generation line (2004), 37 inches, the 8th generation line (2006), 52 inches!

Under the offensive of LCD monitors, PLASMA, plasma TVs have completely lost their living space.All manufacturers who bet on PLASMA technology have completely lost their money.

(Changhong invested US$2 billion. Before that, Changhong was a representative of blue-chip stocks. After that, it became a junk stock.)

The fundamental reason why South Korea, Taiwan, and later the mainland can surpass Japan in the LCD industry is not countercyclical investment.Otherwise, why didn't South Korea, the United States, and Taiwan succeed in the entire 90s?

These latecomers can surpass Japan. The fundamental reason, LCD production technology, developed to the 5th generation, a technology that reduced the difficulty of production on a large scale appeared!

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Why did Japanese manufacturers give Korean manufacturers a chance to overtake? When Korean manufacturers developed the 5th generation line technology, the Japanese did not believe it!

Within the Japanese LCD industry, it is generally believed that the 4th generation line is already the physical limit of LCD industry production.(Note 1)

Because of the basic principles of the liquid crystal production process, they believe that liquid crystal technology has reached its limit!The size of the LCD panel is no longer possible to increase!

The Japanese manufacturers at the time even went to ask Koreans why you are doing such crazy things (investment)!

As soon as Korean technology came out, the Japanese were dumbfounded.

Although the Japanese responded quickly and began to suppress it with all their strength.But in these short years, Koreans, with the support of the government, have grown rapidly.Samsung and LG all developed during that wave.

It is this technology that enables LCD screens to grow rapidly from then on.It was this technology that enabled Taiwan and even the mainland to surpass Japan one after another!

(Note 1, some documents say that the 5th generation is the limit, which is incorrect.)

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As long as this node technology can be found, it will be possible for the LCD industry to corner overtaking.This market valued at hundreds of billions of dollars can provide a steady stream of blood transfusions for the wafer industry!

This involves a core process in the LCD production process.

The production process of TFT-LCD is very close to that of semiconductor wafers.Except for a slightly larger area, many technologies and processes can be used in common.And the accuracy requirement of LCD is very low at this stage, 10 microns is enough!

So what are the main differences between the two?

The liquid crystal display, as you can see from the name, contains the word LCD!This is the difference!

The process of adding liquid crystal to the display is the core process of TFT-LCD!

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Liquid crystal technology was first applied to watches and calculators.TFT-LCD is also gradually enlarged from small liquid crystals after nearly 30 years of evolution.

On the TFT liquid crystal production line (before the 5th generation), the filling method of the liquid crystal is not essentially different from the liquid crystal display used on the calculator.

This process is capillary infusion!

The capillary perfusion method is to put the display on the liquid crystal cell (sponge) after the liquid crystal display is made (fitted and closed), and slowly suck the liquid crystal through the capillary phenomenon.

This method makes sense in the manufacturing process of small displays.Because this process has relatively low requirements on the surrounding environment.Just like we take a straw to absorb water, the surrounding air quality has nothing to do with it.

The early liquid crystal display applications were all electronic products, such as watches and calculators.This kind of craft matches the processing environment of this kind of electronic factory.