like the hard display screen, the flexible AMOLED starts from cleaning the glass substrate, but it is not the substrate of the display screen, but the glass carrier used for process turnover. At present, this glass carrier used by Samsung and BOE is also provided by Corning.
after the glass carrier is cleaned, it is necessary to spin-coat a solution of peelable layer on it, and after curing, a flat basement membrane will be obtained, which will be removed by the thermal effect of laser irradiation after the flexible AMOLED panel is manufactured.
Then spin-coating PI solution on the peelable layer, and after curing, the real solid substrate of flexible AMOLED can be obtained. These processes seem to be similar to the traditional LCD process, and the PI alignment layer of LCD is also produced by the above process. In fact, except for the different formula of PI solution, other equipment and processes are really similar.
after the p>PI substrate is made, the isolation layer for blocking water and oxygen components and the transition layer for strengthening the adhesion of the functional layer of LPTS TFT are made. These productions are actually the traditional sputtering process. The difficult thing is how to design the parameters of each film layer so that it can not only ensure flexibility, but also have better water and oxygen barrier indexes.
the next step is the traditional LPTS TFT functional layer fabrication, which is basically the same as the traditional LCD fabrication process, as long as the processing parameters are adjusted to the range that the PI substrate can tolerate.
then it comes to the key step of evaporation of OLED organic light-emitting layer. The difficulty in making OLED organic light-emitting layer is not only that the coating is too thin and requires high precision, but also its uniformity. In fact, the physical formation mechanism of this layer is not particularly different from that of LTPS process, and the film is formed by intermolecular force or ionic bond of physical materials.
however, because the working state of the organic light-emitting layer is not like that of the LTPS functional layer, it only needs to be turned on and off after a certain value, but to realize the linear presentation of the electron concentration, so the control of the film thickness and uniform value has become the key to the stable mass production of the OLED panel production line.
after the organic light-emitting layer is fabricated, there is a two-package mode to realize device packaging in the mature flexible AMOLED process. One is to make a multi-layer packaging layer with water and oxygen barrier effect on the organic light-emitting layer by using an atomic film-forming process similar to Samsung, and the other is to attach a water and oxygen barrier film on the organic light-emitting layer. However, because the surface of the produced organic light-emitting layer is not flat, it is necessary to make a flat layer before attaching the water and oxygen barrier film, so the production line of temporarily attaching the water and oxygen barrier film is much lower in yield and efficiency, and the mass production is not as good as that of the production line of atomic film formation.
for the packaged flexible AMOLED panel, the peelable layer needs to be removed by the thermal effect of laser irradiation, and then the FPC FOP crimping window is opened on the terminal part of the LTPS. After these tasks are completed, the flexible AMOLED panel can be activated by lighting the organic light-emitting layer. (There is also a process of lighting and activating first, and then stripping) The flexible AMOLED panel after activation basically completes the so-called front-end process of the panel factory.
in the latter stage process of flexible AMO LED display screen, except FOP replacing TAB process of LTPS LCD display screen, other assembly processes are basically the same as COF process of LTPS LCD, and the biggest difference is that the flexible AMO LED display screen lacks the step of installing backlight.
there is also a key quality control process difference between flexible AMOLED display screen and LTPS LCD display screen, that is, when the display function of flexible AMOLED display screen is tested, the control program in the flash memory of driving IC can be rewritten by means of external compensation, and the offset value of display color and brightness caused by the uniformity difference in the manufacturing process of organic light-emitting layer can be repaired within a certain limit of the driving power supply, so that the display effect of flexible AMOLED display screen can present consistent color gamut values within the dynamic range of high and low current as possible.
well, after all this, the flexible AMOLED display screen can basically work normally, and then it only needs to be made into flat, curved or limited flexible display products according to the design needs of the end products. As for why the product shows plane, curved surface or limited flexibility, it mainly depends on the design of the protective cover plate selected during product design.