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How to deal with the difference in film color with vacuum coating equipment?

How to deal with the difference in film color with vacuum coating equipment?

2021-12-24

How to deal with the difference in film color with vacuum coating equipment?





For coating with vacuum coating equipment, there are two types of film color differences (not including stains). One is the inconsistent color of the upper, middle, and lower films of the entire mask, that is, the spectroscopic test curve is different; the second is the color of the single film is inconsistent.


1. The inconsistency of the upper, middle and lower film colors is called poor uniformity of the whole umbrella (cover), also called umbrella difference. The main reason is that there is a problem with the uniformity correction board (correction board).


2. Umbrella pieces are deformed. It is also one of the reasons for the unevenness of the film color, especially the umbrella pieces that have been used for a long time, which used to be uniform, but gradually become uneven, and the deformation of the umbrella pieces may be the main reason.


3. The inconsistency of the film material conditions, especially the sublimation and semi-sublimation film materials being deflected, digging pits, etc., will also seriously affect the uniformity of the entire cover and single chip. Especially when there is a large amount of manual pre-melting, the operation methods of each person are different, and the material conditions obtained will also be different.


Improvement ideas: Fully use the function of the correction board.


Improve strategy:


(1) Adjust the correction plate, try to consider the balance and compatibility of high and low refractive index film materials. If there are two evaporation sources, use their own correction plates independently if possible to avoid interference.


(2) When conditions permit, planetary fixtures are used.


(3) Umbrella shaping. For shaping the umbrella piece, you can first process an R base mold (choose a higher strength raw material), and then reshape the umbrella piece on the base mold. In order to prevent the deformation of umbrella slices, the thickness and raw materials of umbrella slices should be selected appropriately when ordering umbrella slices.


(Iv) Strengthen the management of umbrella pieces, especially the management during placement, to prevent deformation due to improper placement.


(5) Improve the condition of the membrane material, especially when the electron gun evaporates sublimation and semi-sublimation materials, the membrane material cannot be collapsed and digging holes.


(Vi) The film material that can be automatically pre-melted should be automatically pre-melted as much as possible to reduce the influence of human factors.


The correction plate is very effective in correcting the physical film thickness, but it is incapable of correcting the refractive index, so it is very difficult to completely rely on the correction plate to solve the spectral uniformity.


If one correction board needs to correspond to two electron guns (evaporation sources) and a variety of film materials, there will be greater difficulties.


The reasons for the uneven color of the single film:


It is mainly due to the serious unevenness of the substrate, which is quite different from the curvature of the umbrella, and the evaporation angle formed by the upper or lower normal line of the substrate and the evaporation source is quite different. This results in a large difference in the conditions for receiving the film material on each part of a lens, and a large difference in the thickness of the formed film.


In addition, the lens is blocked by the edge of the lens ring (disc), the lens ring (disc) is dirty and contaminates the lens during evaporation, etc., which can also cause film color differences.


Improvement ideas: improve the evaporation angle of the edge of the lens.


Improve strategy:


(1) If conditions permit, use planetary fixtures;


(Ii) Choose a machine with a flat umbrella (large R);


(3) According to the distribution of the umbrella holes and the shape of the substrate, a special zigzag correction board is made.


(Iv) If possible, moving the evaporation source to the middle of the vacuum chamber can also improve the uniformity of the monolithic film color.


(5) Improve the lens ring (disc) to prevent blocking.


㈥ Pay attention to the partial shielding of the edge lens by the corresponding part of the rotating umbrella stand


(Vii) Clean the lens ring (disc)


(Viii) Improve the evaporation of the film material.


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