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LCD manufacturing

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LCD manufacturing is the process of making liquid crystal display (LCD) panels.

LCDs are manufactured in cleanrooms, borrowing techniques from semiconductor manufacturing.

Process

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A class of photolithography known as display lithography is used to etch patterns into substrates.

LCD manufacturing shares some of the process with OLED manufacturing.

The process flow involves multiple separate components that are joined together: a process for making a thin-film transistor (TFT) backplane, a process for making color filters, and a liquid crystal cell process.[1]

Once LCD panels are manufactured, they can be measured for color quality and panel uniformity using characterization equipment.[2]

TFT backplane process

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TFT backplanes are made using photolithography techniques, which involve using photomasks.[1] The photomask(s) are used to create TFTs on a substrate, which involves formation of a gate layer, source/drain layer formation, and contact-hole formation.[1]

The TFT backplane process involves patterning of indium tin oxide (ITO), which is a transparent and electrically conductive material.[1]

Conventional LCDs use a back-channel etched (BCE) TFT display pixel structure.[1]

Liquid crystal cell process

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The cell process involves layer alignment, sealant formation, and depositing liquid crystal. The panels are then bonded and cut into individual displays.[1]

A technique that can be used is one drop fill (ODF).[1][3]

UV photocuring equipment can be used for bonding LCD panels.[3]

Modules

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An LCD module (LCM) is a ready-to-use LCD with a backlight. Thus, a factory that makes LCD modules does not necessarily make LCDs, it may only assemble them into the modules.

An LCD panel is attached to a driver board using anisotropic conductive film.

Generations

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LCD-Glass-sizes-generation
LCD-Glass-sizes-generation

LCDs are manufactured using large sheets of glass whose size has increased over time. Several displays are manufactured at the same time, and then cut from the sheet of glass, also known as the mother glass or LCD glass substrate. The increase in size allows more displays or larger displays to be made, just like with increasing wafer sizes in semiconductor manufacturing. The glass sizes are as follows:

Generation Length
(mm)		 Height
(mm)		 Year of
introduction		 References
GEN 1 200–300 200–400 1990 [4][5]
GEN 2 370 470
GEN 3 550 650 1996–1998 [6]
GEN 3.5 600 720 1996 [5]
GEN 4 680 880 2000–2002 [5][6]
GEN 4.5 730 920 2000–2004 [7]
GEN 5 1100 1250–1300 2002–2004 [5][6]
GEN 5.5 1300 1500
GEN 6 1500 1800–1850 2002–2004 [5][6]
GEN 7 1870 2200 2003 [8][9]
GEN 7.5 1950 2250 [5]
GEN 8 2160 2460 [9]
GEN 8.5[a] 2200 2500 2007–2016 [10]
GEN 8.6 2250 2600 2016 [10]
GEN 8.7[b] 2290 2620 2026 [11]
GEN 10 2880 3130 2009 [12]
GEN 10.5[c] 2940 3370 2018 [13][14]
  1. ^ Sometimes wrongfully referred to as GEN 8.
  2. ^ Sometimes wrongfully referred to as GEN 8.6.
  3. ^ Also known as GEN 11.

Until Gen 8, manufacturers would not agree on a single mother glass size and as a result, different manufacturers would use slightly different glass sizes for the same generation. Some manufacturers have adopted Gen 8.6 mother glass sheets which are only slightly larger than Gen 8.5, allowing for more 50- and 58-inch LCDs to be made per mother glass, specially 58-inch LCDs, in which case 6 can be produced on a Gen 8.6 mother glass vs only 3 on a Gen 8.5 mother glass, significantly reducing waste.[10] The thickness of the mother glass also increases with each generation, so larger mother glass sizes are better suited for larger displays.

Companies

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Companies that have made or sold LCD panels include:

Companies that have produced FPD lithography equipment include Canon and Nikon.[15]

LCD glass substrates are made by companies such as AGC Inc., Corning Inc., and Nippon Electric Glass.

Display lithography equipment include the H803T and H1003T from Canon.[16] Display Technologies, Inc. is a defunct joint venture that manufactured LCD panels.

Materials

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Optically clear adhesives are used to bond display components in the manufacturing process.[17]

References

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  1. ^ a b c d e f g "LCD manufacturing flow".
  2. ^ "Display Characterization".
  3. ^ a b "Liquid crystal display manufacturing process innovation 1: One drop fill (ODF)".
  4. ^ "Sunic system". sunic.co.kr. Archived from the original on March 8, 2021. Retrieved December 22, 2019.
  5. ^ a b c d e f "Size Matters". AU Optronics Corp. (AUO). January 19, 2017. Archived from the original on August 24, 2017.
  6. ^ a b c d Gan, Fuxi (2003-07-16). From optical glass to photonic glass. International Symposium on Photonic Glass (ISPG 2002). p. 1. doi:10.1117/12.517223.
  7. ^ Armorex Taiwan Central Glass Company Archived February 24, 2021, at the Wayback Machine, Retrieved May 20, 2015.
  8. ^ Samsung: SAMSUNG Electronics Announces 7th-Generation TFT LCD Glass Substrate Archived April 4, 2021, at the Wayback Machine, Press release March 27, 2003, Visited August 2, 2010.
  9. ^ a b "Large Generation Glass". Archived from the original on August 23, 2011. Retrieved April 4, 2019.
  10. ^ a b c "8.6G Fabs, Do We Really Need Them? - Display Supply Chain Consultants". March 7, 2017. Archived from the original on March 7, 2017. Retrieved July 3, 2023.
  11. ^ Ross, Young (4 December 2023). "BOE Formally Announces B16 G8.7 IT OLED Fab". DSCC. Retrieved 14 June 2024.
  12. ^ "Company History - Sakai Display Products Corporation". SDP.co.jp. Archived from the original on March 8, 2021. Retrieved April 10, 2019.
  13. ^ "BOE's Gen 10.5 Display Equipment Is a Pie in the Sky for Korean Equipment Companies". ETNews. July 10, 2015. Archived from the original on March 25, 2021.
  14. ^ Shih, Willy. "How Did They Make My Big-Screen TV? A Peek Inside China's Massive BOE Gen 10.5 Factory". Forbes. Archived from the original on March 7, 2021. Retrieved April 10, 2019.
  15. ^ "Global Flat Panel Display (FPD) Lithography Equipment Market Insights and Forecast".
  16. ^ https://global.canon/en/v-square/80.html
  17. ^ Handbook of Visual Display Technology. Springer. doi:10.1007/978-3-642-35947-7. ISBN 978-3-642-35947-7.
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