Manufacturing processes of Screens

manufacturing flow of OLED screen (undetailed)

There are multiple process flows depending on the type of OLED that is fabricated.The scheme below lists all the different types of OLED, and how it affects the process flow ^{1) 2) 3) 4)}. Each process alternative is explained in the respective section of this page.

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There are different deposition methods depending on the organic emissive materials selected for the OLED.

• vacuum thermal evaporation combined with an FMM (Fine Metal Mask) - for small sized displays ⁷⁾: This method is not selective, meaning the material is deposited everywhere in the equipment chamber : a FMM (Fine Metal Mask) is placed on top of the substrate to hide areas where no material should be deposited. The emissive layer of small display OLEDs consists of 3 emissive materials (respectively emitting red, blue and green light) that are placed side by side. Hence, there are actually 3 deposition steps using 3 different FMMs, one for each emissive material.
• For larger sized display, the use of an FMM is not appropriate due to a loss of resolution when the substrate size is increased.

OLED devices are highly sensitive to moisture and oxygen. They require a water vapour transmission rate (WVTR) of less than 10^–6 g/m²/day. For this reason, the encapsulation process is crucial for maintaining a long lifetime. There are multiple encapsulation technologies:

The use of these technologies depends on multiple parameters of the screen.

This method can't be used for large or flexible screens.

This method is used for large rigid screens.

This method can be used for flexible screens.

Sources : ([https://www.wiley.com/en-es/Flat+Panel+Display+Manufacturing-p-9781119161363|Flat Panel Display Manufacturing])